CA2160665C - Method and apparatus for stereotactic radiosurgery and fractionated radiation therapy - Google Patents
Method and apparatus for stereotactic radiosurgery and fractionated radiation therapyInfo
- Publication number
- CA2160665C CA2160665C CA002160665A CA2160665A CA2160665C CA 2160665 C CA2160665 C CA 2160665C CA 002160665 A CA002160665 A CA 002160665A CA 2160665 A CA2160665 A CA 2160665A CA 2160665 C CA2160665 C CA 2160665C
- Authority
- CA
- Canada
- Prior art keywords
- skull
- arm
- frame
- assembly
- mounting
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
- A61N5/00—Radiation therapy
- A61N5/10—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy
- A61N5/1048—Monitoring, verifying, controlling systems and methods
- A61N5/1049—Monitoring, verifying, controlling systems and methods for verifying the position of the patient with respect to the radiation beam
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B90/00—Instruments, implements or accessories specially adapted for surgery or diagnosis and not covered by any of the groups A61B1/00 - A61B50/00, e.g. for luxation treatment or for protecting wound edges
- A61B90/10—Instruments, implements or accessories specially adapted for surgery or diagnosis and not covered by any of the groups A61B1/00 - A61B50/00, e.g. for luxation treatment or for protecting wound edges for stereotaxic surgery, e.g. frame-based stereotaxis
- A61B2090/101—Instruments, implements or accessories specially adapted for surgery or diagnosis and not covered by any of the groups A61B1/00 - A61B50/00, e.g. for luxation treatment or for protecting wound edges for stereotaxic surgery, e.g. frame-based stereotaxis for stereotaxic radiosurgery
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
- A61N5/00—Radiation therapy
- A61N5/10—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy
- A61N2005/1092—Details
- A61N2005/1097—Means for immobilizing the patient
Abstract
The invention includes a rigid frame (18) that is positioned around the skull (12) to define a multidimensional coordinate system. Multiple arms (20, 22) are coupled to the frame, each arm having an attachment assembly (30) movable along a longitudinal axis directed toward the center of the rigid frame assembly. Multiple receptors (32) are either attached to the skull or drilled into the skull for receiving an associated attachment assembly. The receptors provide a mounting base upon which the frame is repeatedly attached and detached from the skull at the same reproducible reference location. Each arm has a multi-station receptacle (36) that receives various attachments used for mounting and attaching the receptors. Special bushings (54) are used to lock the attachment assembly in a preset longitudinal position in relation to the arm. The locked attachment assembly can then be removed from the arm allowing the frame to be removed from the skull while maintaining frame position information.
Description
~o s4/23C63 2 1 6 0 6 6 ~ ~/US94/02718 METHOD AND APPARATUS FOR STEREOTACTIC RADIOSURGERY
AND FRACTIONATED RADIATION THERAPY
BACKGROUND OF THE INVENTION
This invention relates generally to c~luip~ ,nl for pe~ro~ g stereotactic radio~urgc, ~ and more particularly to an app~,-lus that can be det~h~d and lC~ h~d at the same location on a skull to provide a reproducible three-dim~n~iona ef~,~nce when locating and M~ ting inl, ' ~ni~l and head and neck lesions.
StereotA~tic radio~ulE~,. y is the practice of gaining precise access to a specific point in the ClalliUlll lhl~U~ll the application of an eYt~Prn~l three--limP-nsional coordinate system. A conventional ~ ol~rtic system utilizes a brain mapping technique such as Co~ ut~ ;7ed to",Ggraphic (CT) sC~nnin~ or mAgnPtiC resonance imaging (MRI), to produce an image l~ se~ g a "slice" of brain tissue. A series of "slices" cor.~ a co,l,plete study and ~ ,sent a three~ ional picture of the brain that defines the relationship of neurological structures and accurately localizes lesio ~.
The CT or MRI sc~r ning ~;r~ nt iS used in coordination with a frame mounte~ to a patient's skull by pins or screws. The frame provides a l~,fe.~"~ce that defines the multi~;...-n~ional coordinate system used in identifying intl~cl~ulial and head and neck lesions. After being ~tt-~hed to the patient's skull, the frame is~tt~hed to a platform within the scanning e~l..ip...~ The frame keeps the skull in the same position during the lesion loc~li7~~ion process. The frame remains ~tt~rhed to the patient's skull after loc~li7~tion and through ~t.,.~ tic radiosurgcly to keep the skull in the same relative position in relation to the frame reference points.
There are various surgical and radiosurgical procedures pe,rolllled on lesions after their loc~li7~tion inside the skull. For example, U.S. Pat. No. 5,027,818 to Bova et. al. describes a radiosurgical mPthod for destroying lesions by directing a radiation beam into the skull. Bova uses a ~te.~olactic frame to assist in loc~li7ing the target (e.g., lesion) inside the skull. The inl~rr~ l target is then positioned at the focal point of the radiation beam. Multiple r~ tio~ p~tl,-v~ys are then taken through different areas of the brain all traveling though the same target focal point. Since SUB~ JTE SHEET (RULE 26) ~,2,i~d66~
wo g4/23663 PCT/US94102718 each radiation pathway is through a different area of the brain, the amount of radiation applied to heathy brain tissue is minimAl. At the focal point (i.e., lesion location), however, a very si_able radiation dose is delivered which can, in certain cases, lead to obliteration of the lesion.
The radiosurgical process, in some instances, is a much safer t,e ~ t option than conventionAl surgical methods. It is especiAlly illlpGl~lt, however, that the radiation is minimi7Pd on certain critical structures inside the skull. For example, when using radiation t~ rnt on a patient's brain, it is important that a minimumradiation dosage be applied to the patient's optic nerves. The~ole, before radiation t~ llllenl, the physician must carefully decide on each path the radiation beam will travel through the brain to reach target area. To m~intAin the same skull reference location, the frame must remain tightly fActçned to the skull while the physician is planning this radiosurgical strategy.
To prevent d~rn Ige to healthy tissue, it would be preferable to apply lower doses of radiation to the lesion over multiple radiation sessiQnc (i.e, fractionated ~lc.eot~ctiG radiation therapy). Fractionated ~l~,~otactic radiation therapy, however, is prohibitively e~ -s;ve and time consuming since the frame must be re~n~eh~d, and the lesion relQc~li7~d before each radiation therapy seSsiQn Fractionated stereot~ctic r~i~tion therapy would be less eXpencive if the same lesion coordinates could be used for each therapy session. To use the same coordinates for each therapy session, the frame would have to be ~tt~chP-d to the skull in the same position in relation to the skull. Present stereotactic immobili_ation devices or frames, however, cannot be re~tt~rhed to the skull in the same location with acceptable accul..l;y.
Thc.~;fole, the lesion must be reloc~li7ed before each radiosurgical session or the radiation beam may have a focal point that is no longer centered on the lesion. An off-target focal point could damage healthy tissue and critical structures in the brain.
The ~leleotactic frame, while necess~ry to ac.;ul~tely identify the intracranialtarget, is time-col.~u...il-g to attach and is burdensome to carry while ~tt~rhed to a p:~tirntc skull. For example, correctly f~ctening the frame to the skull can take one to several hours. Th~lcfol~;, it is prohibitively expensive to reattach the frame before each radiation therapy session. By r,ecessily, the frame is also large and rather bulky.
The large frarne is necessA y to securely mount the skull to the radiosurgical SUBSTITUTE SHEET (RULE 26) Wo 94~6~3 2 1 6 0 6 6 5 pcrluS94102718 equipment. Since radiation therapy sessions that are typically performed once a day and continue for sevçral weeks, it is ill-p.aclical for a patient to carry the frame around on his head lhluu~hout the entire radiation therapy process.
To reduce the time and cost of radiation therapy, a single radiation lledtll~enttechnique or "one-shot" is pelro..lled that directs an intense radiation beam at the Iesion. This "one-shot" technique in some situations, however, does not destroy a lesion as effectively as fractionated radiation therapy. The high hllmsily radiation bearn also has a greater tendency to d:lmage healthy tissue while traveling through the brain to the lesion. If the lesion is located in certain cranial areas, there is no way to destroy the lesion without also d:-m:~ing some critical brain structures. Even if a "one-shot" radiation tlcat~-.ent were feasible, the patient must still wear the frame while the physician is localizing the target and deciding upon the various paths the radiation beam will travel to the lesion focal point. During this loc~li7~tion period, the frame applies extreme p.es~u.~c on the skull. The p~GSsu~G of the frame is unco---rollable and may cause severe head~ hes. Thus, regardless of whether fractionated radiation therapy or a "one-shot" radio~u~ y ploceSS iS u~ili7~d, it would be beneficial to be able to detach the frame from the patient's skull b.,l~ ~n the various steps of the stereotactic radiosu~el y process.
There are several stereotactic frames used in locating hlt~c~u~ial lesionc.
However, present frames cannot be ~ttached and re~tt~rh~d to a skull at a reproducible lGfe.~,~lce location. Forexample, U.S. Pat. No. 3,357,431 to Newelldes~-~;hes an app~ us fixed to a Cl~iulll via screws mounted into the skull. Thedpp&l~lUS in Newell, however, is not used as a three-d;l..Fn~ional l~fe,e.lcG for CT
sc~nning and only provides a mounting platform for invasive surgical equipment. In addition, the frame of Newell cannot be repeatedly 3tt~ch~d to the skull at the same IGfe~ lce position. U.S. Pat. No. 5,176,689 to Hardy et. al. and U.S. Pat. No.
4,923,459 to Nambu, describe app~us that are attached to the skull to ~ h ...;ne the location and SizG of tumors. However, the app&.~lus in Hardy and Nambu also can not be det~rh~ and acculdlely re~tt~hed to the skull at the same ,.,f~l~,nce location.
TherGfore, the appalatus described in Newell, Hardy, and Nambu are not useful insolving the problems of time and cost that presei.tly exist with loc~ g lesions before p~fol...il,g stereotactic surgical procedures.
SUB~ 111 IJT~ SHEET (RULE 26) wo 94123C63 2 16 0 6 65 PCT/US94/02718 -SUMMARY OF THE INVENTION
It is, the~cfol." an object of the invention to reduce the time and cost of localizing intracranial targets before each fractionated stereotactic radiation therapy session.
Another object of the invention is to increase the accuracy in reAn~ching a sl~,r~otactic frame to a skull at the same reference location in relation to the skull.
A further object of the invention is to increase the variety of stereotactic radiosurgical procedures that can be performed on a patient.
The invention is a system for ~.rol.,ling ~lelcotactic radiosurgical procedures upon a target within a skull. The system comprises a rigid frame that is positioned around the skull to define a multi-ll;.,.c ncional coordinate system. Multiple arms are coupled to the frame, each arm having an ~nArhm~nt assembly that is movable along a longitudin~l axis directed subs~ iAlly toward the center of the rigid frame assembly. Multiple receptors are either Ittach~d to the skull or drilled into the skull for receiving an ~CSoci~trd ~tt:ln~ Cn~ Ac5e...bly. The ~ceptol~ provide a n-o~ ing base upon which the frarne can be repe:~tedly ~ttArhed and det~rh~d from the skull at the sarne reproducible reference loc;~ti- n A drill and tap are slidably ~ttnch:~ble to any one of the arms along the same longitudin:~l axis as the ~csoci~ted ~ttacl~ -t assembly. The drill is used for drilling a bore in the skull at each receptor location and the tap is used to form an intern~l screw thread in such a bore. An insertion mechAnicm is then slidably ~tt~rh~d to the arms to insert a l~,ceplor into the bore.
Each arm has a multi-station receptacle that receives the various ~tt~rhmpntc used for mounting and ~tt~r-hing the receptors. Special bushings are insertable inside the arm receptacles to hold the skull mounting devices along a single ~ u~ling axis sulu~ tiAlly perpe-ndic~ r with the longitudin~l axis of the associated arm. A
locking ...rchAnicm is used to lock the Att~chmPnt assembly in a preset longitu(linAl position in relation to the arm. The locked ~ttArhmrnt assembly can then be removed from the arm allowing the frame to be removed from the skull while l"Aint~;njng frame position information.
SlJBSTITl)TE ~HEET (RULE 26) 216066~
wo 94t236C3 ~ ' ;' pcrtus94tO2718 The invention is used in stereotactic radio~urge,y processes in the following manner. The ~ ,otactic frame is first attached to the skull and holes drilled at the locations where the frame mounts to the skull. Receptors are then instAlled into the skull holes and the frame re~tt,acllPd to the recepto,~ thereby locating it about the skull at a given reference position. The lesion is then loc~li7ed according to the frame .cfelcnce position and a stereotactic radiosurgical procedure pe.rol,l,ed. After the ~,.colActic radiosurgical procedure, the frame is removed leaving the lcccl)lol~~ttached in the skull holes. Before the next stereotactic surgical procedure, the frame is re~tArhrd in the ,cceptc"~ at the same reference position. ~lt~rn~tively, the holes drilled in the skull are used as receptors and the frame ~ttarhed directly into the drilled holes.
The lesion is loc~li7~d by deriving a set of coordinates relative to the frame reference position. Since the frame is re~tt~rh~d to the skull in the same position, the same lesion coordinates are used for each subse~ue-nt stereotArtic radiosurgicalprocedure. Having the capability to reuse the same lesion coordinates allow subsequent radiosurgical procedures to be pc.l~,llled without having to completely reloc~li7e the lesion. Thus, the cost and time of each therapy session is ~cJuGed The fo,~ing and other objects, l~atul~s and advantages of the invention will beco~lle more readily app~,nt from the following det~iled desc,iption of a p.e~,~d embodiment of the invention which proceeds with reference to the acco,ll~ ying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. I is a side view of a stereotactic frame acco,ding to the invention rhed to conventional radiation appa-~tus which may be employed for stereotactic radiosurge,y.
FIG. 2 is a front view of the ~ otactic frame shown in FIG. 1.
FIG. 3 is an enlarged side view of a front arm for the stereotactic frame shown in FIG. 1.
FIG. 4 is an enlarged side view of a rear arm for the stereotactic frarne shown in FIG. 1.
FIG. 5 is an enlarged front view of the rear arm shown in FIG. 4.
SUB~ 1~ I IJTE SHEET (RULE 26) wo g4n3~ 2 1 6 0 g ~ PCTrUSs4/02718 FIG. 6 is a view taken along line 6-6 in FIG. 5.
FIG. 7 is a cross-sectional side view of a clamp assembly.
FIG. 8 is a view taken along line 8-8 in FIG. 7.
FIG. 9 is a side view of a drill assembly.
FIG. 10 is a side view of a tap assembly.
FIG. 11 is a side view of an insertion assembly.
FIG. 12 is a side view of an ~tt~rhmrllt assembly.
FIG. 13 is a view taken along line 13-13 in FIG. 12.
FIG. 14 is an enlarged cross-section of the r~ceplor shown in FIG. 12.
FIG. 15 is a side view of the ~n~rhm~nt assembly in a locked position.
FIG. 16 is a view taken along line 16-16 in FIG. 15.
FIG. 17 is a side view of the ~tt~rllment assembly shown in FIG. 15 removed from the frame arm.
FIG. 18 is a side view of the ~tt~rhmrnt assembly shown in FIG. 12 inserted directly into a skull hole.
FIG. 19 is a view of an alternate embodiment of a l~eeplol.
FIG. 20 is an enlarged top view of the leceplor of FIG. 19.
FlG. 21 is a view taken along line 21-21 in FIG. 20.
DETAILED DESCRIPTION
FIG. 1 is a side view of a ~ iotactic frame 18 according to the invention ~tt~rhed to a gantry 14 of a conventional radiation appal~us, such as a linear accelerator. The plefe.l~d embo liment of the invention is shown and described herein in conjunction with a linear accelerator. The method and app~alus of the present invention can be equally well impleme~tçd with several brain u~apping techniques for loc~li7ing and defining targets such as angiography, CT sç~nning, MRI
(m~etiC reson ~nc~ ima~ng) and PET (positron emission tomogMphy). The linear accelerator in FIG. 1 is used for stereotactic radiosurgery and fractionated radiation theMpy on intracranial lesions inside a skull 12. A collim~tor 17 is ~tt~rhed by a SuppGIl arm 16 to the gantry 14. The gantry 14 carries the radiatior, ell~illingcollimator 17 in an arc around the skull 12. The frame 18 (ring) has a circular outside surface that mounts inside a circular bracket 24. In the present embodim~-nt of the SUBSTITUTE SHEET (RU~E 26) ~ ' ~ 94n3663 2 ~ 6 ~ ~ ~ 5 PCT/US94/02718 invention, ring 18 is commercially available Bracket 24 is ~tt~hed to a floor-stand (not shown) Arms 20 and 22 attach the ring 18 to the skull 12 Stereotactic radioslllge"/ procedures for identifying and destroying inner cranial lesions, are well known to those skilled in the art and, the,~folt;, will not be described in detail A specific procedure and apps~ulus for performing stereotactic radiosulgcl~ is described in U S. Pat. No. 5,027,818 to Bova.
The first step in the stereotactic radiosurgery process is loc~li7SItion of the lesion (e.g., tumor). One method of loc~li7~ion is CT and involves fitting the skull 12 inside a stereotactic frame 18 as illustrated in FIG. 1. A stereotactic localizing device is then ~t~clled to the frame. The subsequent brain mapping and target definition produces precise, x, y, z, coordinates of the target (to an accuracy of less than 1/2 millimeter) relative to the stereotactic frarne.
The patient is aligned in the gantry li and contiguous slices, beginning at the level of the ring 18 and advancing superiorly past the top of the patient's skull 12, are o~t~ned. If the target volume is identified in the coll")ule.ized tomography image, the x, y, _, coordinates of the target volume are again recalculated to provide a double check of the x, y, z, coordinates previously derived relative to the stereotactic ring 18.
The cr scan provides three dimensional anatomical information of the patient that allows a solid patient model to be constructed.
The data from the CI' scan, angiographic films and/or MRI is then transferred to a collmle.~cially available dosin-F tl y co~ ,ul~r system (not shown). For high single fractions of radiation to be delivered to the target volume, the radiation source emitted from collim~tor 17 is moved through multiple arcs around the skùll 12. For the radiotherapist and neuro~ul~;~on to be able to ex~mine the consequence of each portion of the arc prior to radiating the patient, the dosimetry system displays each arc se~,lllent on a computer screen. If any particular arc results in an extensive dose of radiation to a critical structure inside the brain, the therapist alters the arc parameters to avoid the anatomical area of concern. Once the acceptable radiation ~...ent schelne has been derived, the coordinates of the isocenter (focal point of the radiation beam), the collimator coordin~tes, and the arc parameters are transferred to theradiation app~lus 14 and the radiation administered to the patient.
SUBS~ITUTE SHEET (RULE 26) .2160.6'65 wo 94n3663 PCT/US94/02718 --As explained above, the target coordinates are ~enel~ted relative to the frarne 18. The~fGle, moving the ring 18 in relation to the skull 12 would cause the radiation beam focal point to be misaligned with the target location. To prevent focal point misalignm~nt, conventional stereotactic rings are kept on during the entire loc:~li7~tion process. In addition, due to the extensive time re(luirel~ents required for all of the loc~li7:~tion procedures described above, fr~ctiol-~ted stereotactic radiation therapy is not tAtel,sively ~II~"I,ed.
In the present invention, however, the arms 20 and 22 can be det~rhP-d from the skull 12 and re~tt~rhed to the skull 12 at the sarne reference location. This repe:-tnble positioning of ring 18 at the same x, y, z coordinates in relation to the skull allow the radiation app~lus 14 to use the same coordinates for each radiation therapy session. The ring 18 can also be removed between various loc~li7~tion procedures, for example, while the physician computes and optimizes radiation doses.
To explain further, FIG.2 shows a front view of the sl~.~,otactic ring 18 shown in FIG. l . The ring 18 is seated inside the bracket 24 and has four arms 20, 22, 26, and 28 ext~nrling along a longitu~lin~l axis sul,sl ~uti~lly parallel with the center axis of the ring 18. Each arm is ~tt~rhed to the skull 12 by an ~tt~rl""~.~t assembly 30. The .~.t~ l""f 1" assembly sits in a l~,ceptor 32 residing in the skull 12.
The arms are positioned so that the att:l~ h...f ~-~ assembly 30 co~t~rtc with skull 12 in a direction subsl;~ti~lly pe~en~ic~ r with the t~ngenti~l plane passing through the skull contact point.
For example, front arms 20 and 26 are angled toward each other slightly more than rear arms 22 and 28 to ~ccolmt for the inclined surfaces on the front of skull 12.
The rear arms 22 and 28 are less angled to provide perpe~ icul:~r contact with the ~u~ nti~lly round surface at the back of skull 12. The perpendicular contact of each ~tt~chm~nt assembly 30 allows a m~imum amount of skull bone to surround each receptor 32. By m~ximi7ing the amount of skull bone surroun~ing each receptor, the stability in which the receptor 32 is seated in the skull is increased. As will later be more fully described, the arms are detsu l1~hle from ring 18. This feature permits ~tt~h.,.f nt of the two types of arms, arms 20,26, on the one hand, and arms 28, 30, to dir~.~,nt locations on the ring to accommodate differently shaped skulls.
.~' L .. ~
SUBSTITUTE SHEEr (~ E 26) 21 6~0 6 B5 ~/US94/02718 Similarly, different numbers of each type of arm may be used up to and including all of the arms being of one type or the other.
The l.,CGplO~ provide a stable mounting foundation for each :Itt~rhmPnt assembly 30 and allow the ring 18 to be :ltt~rhrd and det~rhr-d from the skull at a reproducible reference location. For example, the attachment assembly 30 is removable from the frame arm to allow the ring 18 to be removed from the skull 12.
However, keeping the receptors 32 in the skull allow each ~n~rhment assembly 30 to be reseated in an associated receptor 32 at the previously defined reference location.
Thus, the ring 18 can be repeatably repositioned in the same location in relation to the skull 12. A series of skull processing procedures are performed on skull 12 before inserting ~Gceplol j 32 and are described in detail below.
FIG.3 is a side view of the front arm 20 and FIG.4 is a side view of the rear arm 22 shown in FIG. 1. Both the front and rear arms have a shaft 40 with oppositely inclining sides 34. The front arm 20 has a rotated assembly section 44 that is skewed in relation to the shaft 40. In Fig.4, the assembly section 45 is aligned with shaft 40.
Both the front and back arms have equal di~ te~ bushing holes 36 and equal di~mPt~.r lock screw holes 38. The shaft 40 of rear arm 22 is shown inserted into the ring 18.
FIG.5 is a front view of the rear arrn 22 shown in FIG.4. The shaft of each front and back arm has a set of female conical bores 46 for receiving a screw 48through a hole in ring 18. FIG. 6 is a cross-section of the ring 18 and arm 22 shown in FIG.5. A dovetail slot in ring 18 receives the shaft 40 of arm 22. The applo~liate conical bore 46 (FIG. 5) is aligned with the ring hole 50 according to the size of the patient's skull and lesion location. Ring hole 50 has internal threads that interlock with tLhe threads of screw 48. Thus, rotating screw 48 into hole 50 forces the conical tip of screw 48 against the conical bore 46. The tip of screw 48 forces shaft 40against the back face of the dovetail slot holding arm 22 securely in the ring 18.
F~G.7 is a side view of a clamp assembly 52 and FIG. 8 is a view taken along line 8-8 in FIG.7. A clamp bushing 54 is insertable inside hole 36 (see FIG.5). The bushing 54 has an internal threaded hole that receives and interlocks with the threads of clarnp shaft 56. The front end of clamp shaft 56 is coupled to a swiveled clamping mount 58 and the rear end of clamp shaft 56 is ~tt~rhed to a crank 60. The bu~hing SUBS I 1~ lJTE SHEET (RULE 26) wo 94/23CC3 2 1 6 0 6' 6 5 PCT~S94/02718 ~
54 is locked to the arm 22 by a lock screw 62. The threads of lock screw 62 engage with the internal threads of hole 38 (see FIG. 5) and hold a flange 66 on bushing 54 against the rear face of arm 22. Lock screw 62 allows quick insertion and extraction of various buchingc from hole 36, however, alternative ~ttz~ nt ~..PÇI~niCmC could also be used to attach various app~atus to arm 22.
The clamp assembly 52 is used to initially attach the ring 18 and arms 20,22, 26, and 28 to the skull 12 and is inct~lled by inserting bushing 54 into hole 36. A slot 64 in bushing 54 (FIG.8) is positioned to pass around lock screw 62. Bushing 54 is then rotated so that flange 66 slides underneath lock screw 62. Lock screw 62 is then screwed further into hole 38 pressing against the flange 66 and holding the bushing 54 firmly against arm 22.
Rotating crank 60 moves crank rod 56 forward pushing mount 58 against skin 67 of skull 12. The mount 58 swivels slightly as it presses against the skull 12 so that the front face of mount 58 lies flat against the skull. Each of the four ;~tt~ck...~nt assemblies (i.e., one for each arm) are tight~r ed until the frame is securely f~ct~ned to the skull 12. The clamp assembly 52 is removed from arm 22 by ul~s~ ving lock screw 62 and rotating flange 66 out from under lock screw 62. Notch 64 is then centel~d about lock screw 62 and bushing 54 removed from hole 36. The clamp assembly 52 shown in FIG. 7 is identi~l for each frame arm and provides support for the frame during the subsequent drilling and ~ rllm~nt p.vcesses desçribed below.
FIG. 9 is a side view of a drill assembly 68. The drill assembly inchldes a drill bushing 74 insertable into hole 36 of arm 22, a drill 70, and a drill bit 72. The drill bushing 74 is ~n~rh~d to arm 22 by lock screw 62 in the same ~ ner as clarnp asse,--bly 52 in FIG.7.
The drill assembly 68 is used for boring holes into skull 12. The skull holes are drilled one at a time by first removing one of the clamp assemblies 52 as described above in FIG.7. A drill bushing 74 is then inserted and locked into hole 36 and drill 70 enabled so that drill bit 72 begins boring a hole 76 into skull 12. After boring hole 76, drill bit 72 is removed from the skull 12 and the drill assembly 68 removed from arm 22. The drill assembly is also removed from arm 22 in the same manner as clamp assembly 52 (see FIG.7). Various drill bits can be utilized to create different skull holes. Different di~meter drill bits require different bushings having SUB~ 111 lJTE SHEET (RULE 26) wog4/23663 216066~; PCT/US94tO2718 different-sized bores therein for receiving the bit. Preferably, the clearance btl~ce the bit and the bushing hole is approximately .01 mm. The type of holes drilled in skull 12 depend on the type of receptors inserted into the skull.
FIG.10 is a side view of a tap assembly 78 which includes a tap bushing 80 insertable into hole 36 of arm 22. The tap bushing 80 receives a tap bit 82 that is 3~h 3ble to a tap chuck 83. The tap assel,.bly 78 is ~tt:~rhed and det73chpd from arm 22 in the same manner as the clamp and drill 3cs~ blies 52 and 68,1espccli~ely, as previously described above. The tap assembly is used to tap threads in the hole 76 previously drilled by drill bit 72 (FIG.9). However, if a non-threaded receptor or a self-threading receptor is used, tap assembly 78 is not necess~3~ y.
FIG. l l is a side view of an insertion assembly 84 which includes a shaft 88 coupled at the front end to a wrench fitting 92 and is coupled at the rear end to a crank 90. The shaft 88 is held by the same bushing 80 used in tap assembly 78 (FIG.
10). The wrench fitting 92 is insertable into an internal socket in ,~,ceptor 32. After the tap bit 82 is removed from bushing 80, shaft 88 is inserted into bushing 80 and receptor 32 :ltt 3nhed to the wrench fitting 92. Crank 90 is then rotated c~3ucirlg es~rn~l threads on l~ceptor 32 to interlock with the int~rn 31 threads in skull hole 76.
The r~~l)tor 32 is screwed tightly into hole 76 so the receptor can support frame 18.
FIG.12 is a side view of the ~tt~rl....~ asselllbly 30 shown in FIG. 2 and FIG. 13 is a view taken along line 13-13 in FIG. 12. The 5~11731'~ assembly inrludes a screw pin 95 insertable into a screw pin bushing 102. The screw pin 95 has a lockable head 96 at the rear end with a notch 97, a threaded midsection 98 that interlocks with the il~tern~l threads of the screw pin bushing 102, and a tapered tip 100 at the front end. The rear face of screw pin bushing 102 has four screw holes 104 (~G.13) used in coo~ination with a lock washer as will be described in further detail below in FIGS.15 and 16.
The ~tt7lchm~0nt assembly 30 is again inserted and e~ ed from arm hole 36 in the same manner as the clarnp, drill, and tap assemblies. After the insertionassembly 84 (FIG.11) is removed from arrn 22, screw pin bushing 102 is inserted and locked into hole 36. Screw pin 95 is then rotated with a screw driver (not shown) into bushing 102. Bushing 102 has a close tolerance bearing bore on each end to guidethe screw pin 95 repe-~t~bly regardless of the insertion di~t~nce into bushing 102. The SUBSTITUTE SHEET (RULE 26) 2i6066~
Wo 94n3663 pcrnJS94/02718 bore on the left receives the shaft of pin 95 while the bore on the right receives head 96. Between the bearing bores in bushing 102 is a threaded section which engageswith external thread 98 on screw pin 95 thus allowing screw pin 95 to be driven forward. As screw pin 95 moves forward in the buching 102, tapered tip 100 is forced into the socket of receptor 32. Screw pin 95 is sufficiently tight~-ned against receptor 32 so that the frame 18 (FIG. I) can not be inadve,t~.ntly ~licmounted from the receptors or moved in relation to skull 12.
FIG. 14 is a cross-section of the receptor 32 shown in FIG. 12. The socket inside receptor 32 col~",l,ses a wrench receiving section 106 and a screw pin receiving section 108. Section 106 is used for receiving the wrench fitting 92 of insertion assembly 84 (FIG. 11) and section 108 receives the tapered tip 100 of screw pin 95 (FIG. 12). While inserting ~. ceplor 32 in the skull (see FIG. 11), the wrench fitting 92 interlocks inside section 106, allowing the receptor to be screwed into the skull hole 76. After the ,~ce~tor is securely f~ct~n~od into the skull, the screw pin 95 is inserted into the 1~ ceptor 32 pressing the tapered tip 100 of screw pin 95 against the interior walls of section 108.
FIG. 15 is a side view of screw pin 95 locked to the screw pin bushing 102 by a lock washer 112. The lock washer 112 is held to bushing 102 by a screw 110. FIG.
16 is a front view of the lock washer 112 shown in FIG. 15. The lock washer 112 has a finger 116 that rides inside the notch 118 (in Fig. 13) in screw pin 95. Screw 110 is insertable through lock washer slot 114 into any one of the screw pin bushing holes 104.
After the screw pin 95 has been inserted sllffit~i~ntly into the receptor 32 (FIG.
12), lock washer 112 is slid over the head 96 of screw pin 95 as the lock washerfinger 116 rides inside screw pin notch 118. When the lock washer 112 lies flat against the rear face of bushing 102, screw 110 is inserted into the hole 104 that happens to be access;ble through lock washer slot 114. If l-f cess:~ y, lock washer 112 can be slid off of pin 95 and turned over to place slot 114 in a location relative to one of holes 104 to permit in~t~ tion of screw 110 as shown in FIG. 16. Screw 110 isthen tightPned clamping lock washer 112 against the rear face of bushing 102. The lock washer 112, when tight~ned to bushing 102 by screw 110, prevents screw pin 95 from rotating inside bushing 102. Thus, the lateral position of the arm 22 is locked at SUB~ T~ SHEET (RULE 26) 2iB0665 wo 94n3663 PCT/US94/02718 its present location which conctit~ltes the frame ,cr.,l~nce position.
FIG. 17 is a side view of the ~tt:l~hm~nt assembly 30 shown in FIG. 15 removed from the frame arm 22. To remove the frame from the patients skull, the ~n~rhmçnt assembly 30 must be removed from arm 22. However, it is nccessr.. y that the same lateral screw pin position be used when the frame is re~tt~rh~d to the skull 12. The.cfo~" the entire locked s-tt~rh...f nt assembly 30 is removed from arm 22 so that the screw pin position is 1,.%;nts.il~
For example, to remove the frame 18 from skull 12, the screw pin bushing 102 is first removed from arm 22. Bushing 102 is removed by unscrewing lock screw 62from arm 22 then rotating bushing 102 counlel-clockwise until flange 66 no longer resides under lock screw 62. Notch 64 in bushing 102 (FIG. 8) is then centc.Gd around lock screw 62 and the bushing 102 e~llacled from arm hole 36. The ~tt~hm~nt assemblies for the ~ g three arms 20,26, and 30 are removed in thesame fashion. The frame is then lifted up over the skull 12.
It is illl~ ;Ult to note that the ~t~rhm~nt assembly 30 l~lllaih~s in the lockedposition shown in FIG. 17 throughout the Sl~ o~ tic r~dios...~,e"~ process. Thus, the lateral position of frame 18 in relation to skull 12 ~c~ ns intact. In addition, the longitu(iin~l and l~tituAinFll positions of the frame in relation to the skull are preserved by the IGceplul~ 32 that remain ~tt~ched in the skull in between M~ tion seS~ionc.
Thus, the same frame position in relation to the skull 12 can be repeatably ob~ ed by reinserting the locked ~tt~-k-.-~nt assemblies 30 back into the ~ccoci~t~d arms and reclamping the screw pin bushing 102 with the lock screw 62. As long as the ~tt~rh.~ t assembly remains in the locked position shown in FIG. 17, the frame can be removed and reS~tt~rhed to the skull as many times as dictated by the stereotactic radiation therapy.
After completion of the radiation therapy, the lock washer 112 is det~h~d from bushing 102 and the ~tt~hn.~nt assembly 30 used for another patient. A frame ring 18 and a set of frame arms can be allocated for a single patient over the duration of the radiation l~ or, alle..,atively, the same ring and arms can be used by multiple patients by readjusting the arms for each p:~ti~nt~ skull dim~n~ions (see FIG.
5). It is illlpollânl to identify each arm and record the mounting location for each arm on ring 18 as well as the bore, like bores 46 in FIG. 5, used to mount the arm on the SUB~J~JLITE S~EET ~RULE 26) 216~665 wo 94n3663 K:T/US94/02718 -ring. This ensures that the entire frame is acculately l~ cse~hled when additional fractionated radiosurgery is to he pelrolllled. If multiple p~tientC share the same frame, a set of individual ~tt~hm~ont assemblies 30 are ~ tQined for each patient.
It is important to note that all clamping, drilling, tapping, insertion, and ~tt~ h~ nt assemblies reside along a single longitudin~l axis. ~int:~ining a single longitudinal axis ensure that the screw pins attach symmetrically inside the receptor socket and increase frame stability.
FIG. 18 is a side view of the ~tt:~chm~nt assembly 30 shown in FIG. 12 inserted directly into a skull hole 120. In another embodiment of the invention, the frame can be ~tt~hf d directly into skull hole 120. The process for ~ rh;nf~ theframe to the skull is identicSIl to the process described above except that the drilling procedure (~IG. 9) is pelr(,l,-,ed such that the skull hole 120 is tapered to receive the conical tip 100 of screw pin 95. The tapping and ,~ceplor insertion procedures are then no longer l~luil~d. The lateral coo~inates of the frame are pre~rved by thelocked ~tt ~ .t a~se",bly 102, and the lon~itu~in~l and l:ltitu~in~l coordinates of the frame are preserved by the locations of the drilled skull holes 120 that remain in the patient for the entire ~le,~olactic M~i~tion t~e~ nt The embodiment shown in PIG. 18 leaves a visually less obvious frame receptor in the patient's skull. The direct frame ~tt.~çk~..e~-t process also requires fewer steps to install the frame and requires fewer assemblies to initially attach the frame to the skull. Various skull hole, drill bit, and screw pin designs can be uhlized to perform the steps des~ribed above. ~lttorl ~te assemblies can also be incol~Gl~lt;d into the arm holes for other sl~-~,olactic radiosurgery procedures. All ~cse~blycol.,ponel,~ are pl~fc.~bly titanium for MRI and CT co",palibility except for the arms which are ~lu~ir.~ or plastic.
Rece~Jtol~ imbedded in the skull are superior to bore cavities bored into the bone surface. Repe~ted frame/pin ~ttz~l"llf n~ Uil~S a relatively hard surface.
The overall process for using the stereotactic frame according to the invention is now des~ribed The frame arms 20,22, 26, and 28 (FIG. 2) are first adjusted inring 18 acco~ding to the size of the patients skull. The clamp assemblies 52 (FIG.7) are locked into the arm holes 36 and the clamps ~tt~ e d to the patients skull. After the clamps are tightened to the patients skull, one of the clamp assemblies 52 is SUB~ 11 1 IJTE SHEET (RULE 26) wo 94123C63 Pcr/uss4to2718 removed and replaced with the drill assembly 68 (FIG. 9). A hole is then drilled in the skull along the same axis as previously defined by the clamp assembly 52. After the hole is drilled in the skull, the drill assembly is removed, and if necessr~l y, the tap assembly 78 (FIG. 10) is inserted into the arm hole 36. After the skull hole is tapped, the tap assembly 78 is removed from the arm, and if required, the insertion assembly 84 (FIG. I 1 ) is inserted into the arm. The insertion assembly is used to insert a receptor 32 into the tapped skull hole and then removed from the frame arm. The ~nark...~l-t assembly 30 (FIG. 12) is then in~t~lled in the arm and the ~nslrhm~nt assembly screw pin 95 inserted into the receptor 32.
The above process is pe.l~ led for the ,~ ing three arms so that each arm has an associated ~n:lch~f nt assembly inst~lled in a receptor (see FIG. 2). Each ~tt~chment assembly screw pin 95 is then locked to the associated screw pin bushing 102 with a lock washer 112 and screw 110 as shown in FIG. 15. At this point, theframe 18 is securely ~tt~rhed to the skull and the loc~li7~tion process begins. After the initial loc~li7ation process and after the first radiation ~le~t,.~ , the frame may be e..lo~ed from the patient by uoscl~ g the lock screws 62 and removing each ~tt~çl""c~t assembly 30 from its arm (FIG. 17). The locked ~ l,",. .,~ asse,-lblies 30 are labeled and preserved for further t~ n.~ t~ on the patient. The patient carries the .~,cept~ 32 in his skull throughout the stereotactic r~ tion therapy.
At each ~ubse~uenl radiation therapy sescion~ the frame 18 is positioned around the p~t;eUl~ head and the locked ~n~rhment ~ccemhlies 30 reinserted into the ~CSOf i~ted arm holes 36. The ~tt~rk",lonl assemblies are then forced into the .eceplo.~ 32 by lock screw 62. The radiation therapy is then carried out withouthaving to relocali~ the target. After completion of the therapy session, the frame 18 is again removed and the :~ttzl~hm~nt acsemblies stored for the next radio~ulE ical session. Thus, fractionated stereotactic radiosurgery may be performed at a reasonable cost.
During the times between therapy sessions, .ecepto.~ 32 remain fixed in the p~tient~ skull and extend just above the surface of the skin as shown in Fig. 12. At the conclusion of the fractionated stereotactic radiosurgery according to the present invention, receptors 32 are unscrewed using assembly 84 as shown in FIG. 11. Theskin around the former location of the receptor is then closed and treated as n~ces~ry SUBS I I I LITE SHEET (RULE 26) WO 94n3c63 2 1 6 0 6 65 PCT/US94tO2718 to ensure satisfactory hç~ling.
Turning now to FIG. 19, illustrated therein is another embodiment of a ptor 130 which pe~ ls a similar function to ~ce~)lor 32 in FIG. 12. In the embodiment of FIG. 19 a drill assembly ( not shown) similar to drill assembly 68 in FIG. 9 is used to create a bore 132 in skull 12. The drill assembly is connt.cted to frame 18 in the l.,almer previously desclibed and a drill bit (also not shown) which is smaller than drill bit 72 in FIG. 9 is used to create bore 132.
Receptor 130 includes a lug 134 which is received in bore 132. Receptor 130 further includes a conical opening 136 which receives the lower portion of tapered tip 100 as shown in FIG. 19. The perimeter of receptor 130 includes a circular flange 138 having a pair of countersunk holes 140, 142 the.tth-~)ugh.
In use, a bore, like bore 132, is drilled as described above opposile each of the arms in frame 18. Next, a spot of glue is placed on lug 134 and/or in bore 132. When the lug is pressed into the bore, receptor 130 is firmly secured to skull 12 without requiring a larger bore to be drilled in the skull, as described in connçction with the emb~im~-nt of FIG. 11. In the event the glue is not sufficient to p~pell~/ secure receptor 130, ~dition~l small pilot holes can be drilled in skull 12 lhl~u~;ll holes 140, 142 in the ~ceptor to permit screws, like screws 144, 146 to be in~t~lled to secure the ~,ceplol to the skull. After inst~ tion, pin 95 is inct~lled with its ~csociated bushing (in FIG. 12) so that tip 100 is received in the receptor as shown in FIG. 19.
Having desclil,cd and illustrated the principles of the invention in a prefell~,d embodirn~nt thereof, it should be appa.ent that the invention can be modified inarr~ngernert and detail without dep&.ling from such principles. I claim all modific~tions and variation coming within the spirit and scope of the following clalms.
SUBSTITUTE SHEET ~RULE 26)
AND FRACTIONATED RADIATION THERAPY
BACKGROUND OF THE INVENTION
This invention relates generally to c~luip~ ,nl for pe~ro~ g stereotactic radio~urgc, ~ and more particularly to an app~,-lus that can be det~h~d and lC~ h~d at the same location on a skull to provide a reproducible three-dim~n~iona ef~,~nce when locating and M~ ting inl, ' ~ni~l and head and neck lesions.
StereotA~tic radio~ulE~,. y is the practice of gaining precise access to a specific point in the ClalliUlll lhl~U~ll the application of an eYt~Prn~l three--limP-nsional coordinate system. A conventional ~ ol~rtic system utilizes a brain mapping technique such as Co~ ut~ ;7ed to",Ggraphic (CT) sC~nnin~ or mAgnPtiC resonance imaging (MRI), to produce an image l~ se~ g a "slice" of brain tissue. A series of "slices" cor.~ a co,l,plete study and ~ ,sent a three~ ional picture of the brain that defines the relationship of neurological structures and accurately localizes lesio ~.
The CT or MRI sc~r ning ~;r~ nt iS used in coordination with a frame mounte~ to a patient's skull by pins or screws. The frame provides a l~,fe.~"~ce that defines the multi~;...-n~ional coordinate system used in identifying intl~cl~ulial and head and neck lesions. After being ~tt-~hed to the patient's skull, the frame is~tt~hed to a platform within the scanning e~l..ip...~ The frame keeps the skull in the same position during the lesion loc~li7~~ion process. The frame remains ~tt~rhed to the patient's skull after loc~li7~tion and through ~t.,.~ tic radiosurgcly to keep the skull in the same relative position in relation to the frame reference points.
There are various surgical and radiosurgical procedures pe,rolllled on lesions after their loc~li7~tion inside the skull. For example, U.S. Pat. No. 5,027,818 to Bova et. al. describes a radiosurgical mPthod for destroying lesions by directing a radiation beam into the skull. Bova uses a ~te.~olactic frame to assist in loc~li7ing the target (e.g., lesion) inside the skull. The inl~rr~ l target is then positioned at the focal point of the radiation beam. Multiple r~ tio~ p~tl,-v~ys are then taken through different areas of the brain all traveling though the same target focal point. Since SUB~ JTE SHEET (RULE 26) ~,2,i~d66~
wo g4/23663 PCT/US94102718 each radiation pathway is through a different area of the brain, the amount of radiation applied to heathy brain tissue is minimAl. At the focal point (i.e., lesion location), however, a very si_able radiation dose is delivered which can, in certain cases, lead to obliteration of the lesion.
The radiosurgical process, in some instances, is a much safer t,e ~ t option than conventionAl surgical methods. It is especiAlly illlpGl~lt, however, that the radiation is minimi7Pd on certain critical structures inside the skull. For example, when using radiation t~ rnt on a patient's brain, it is important that a minimumradiation dosage be applied to the patient's optic nerves. The~ole, before radiation t~ llllenl, the physician must carefully decide on each path the radiation beam will travel through the brain to reach target area. To m~intAin the same skull reference location, the frame must remain tightly fActçned to the skull while the physician is planning this radiosurgical strategy.
To prevent d~rn Ige to healthy tissue, it would be preferable to apply lower doses of radiation to the lesion over multiple radiation sessiQnc (i.e, fractionated ~lc.eot~ctiG radiation therapy). Fractionated ~l~,~otactic radiation therapy, however, is prohibitively e~ -s;ve and time consuming since the frame must be re~n~eh~d, and the lesion relQc~li7~d before each radiation therapy seSsiQn Fractionated stereot~ctic r~i~tion therapy would be less eXpencive if the same lesion coordinates could be used for each therapy session. To use the same coordinates for each therapy session, the frame would have to be ~tt~chP-d to the skull in the same position in relation to the skull. Present stereotactic immobili_ation devices or frames, however, cannot be re~tt~rhed to the skull in the same location with acceptable accul..l;y.
Thc.~;fole, the lesion must be reloc~li7ed before each radiosurgical session or the radiation beam may have a focal point that is no longer centered on the lesion. An off-target focal point could damage healthy tissue and critical structures in the brain.
The ~leleotactic frame, while necess~ry to ac.;ul~tely identify the intracranialtarget, is time-col.~u...il-g to attach and is burdensome to carry while ~tt~rhed to a p:~tirntc skull. For example, correctly f~ctening the frame to the skull can take one to several hours. Th~lcfol~;, it is prohibitively expensive to reattach the frame before each radiation therapy session. By r,ecessily, the frame is also large and rather bulky.
The large frarne is necessA y to securely mount the skull to the radiosurgical SUBSTITUTE SHEET (RULE 26) Wo 94~6~3 2 1 6 0 6 6 5 pcrluS94102718 equipment. Since radiation therapy sessions that are typically performed once a day and continue for sevçral weeks, it is ill-p.aclical for a patient to carry the frame around on his head lhluu~hout the entire radiation therapy process.
To reduce the time and cost of radiation therapy, a single radiation lledtll~enttechnique or "one-shot" is pelro..lled that directs an intense radiation beam at the Iesion. This "one-shot" technique in some situations, however, does not destroy a lesion as effectively as fractionated radiation therapy. The high hllmsily radiation bearn also has a greater tendency to d:lmage healthy tissue while traveling through the brain to the lesion. If the lesion is located in certain cranial areas, there is no way to destroy the lesion without also d:-m:~ing some critical brain structures. Even if a "one-shot" radiation tlcat~-.ent were feasible, the patient must still wear the frame while the physician is localizing the target and deciding upon the various paths the radiation beam will travel to the lesion focal point. During this loc~li7~tion period, the frame applies extreme p.es~u.~c on the skull. The p~GSsu~G of the frame is unco---rollable and may cause severe head~ hes. Thus, regardless of whether fractionated radiation therapy or a "one-shot" radio~u~ y ploceSS iS u~ili7~d, it would be beneficial to be able to detach the frame from the patient's skull b.,l~ ~n the various steps of the stereotactic radiosu~el y process.
There are several stereotactic frames used in locating hlt~c~u~ial lesionc.
However, present frames cannot be ~ttached and re~tt~rh~d to a skull at a reproducible lGfe.~,~lce location. Forexample, U.S. Pat. No. 3,357,431 to Newelldes~-~;hes an app~ us fixed to a Cl~iulll via screws mounted into the skull. Thedpp&l~lUS in Newell, however, is not used as a three-d;l..Fn~ional l~fe,e.lcG for CT
sc~nning and only provides a mounting platform for invasive surgical equipment. In addition, the frame of Newell cannot be repeatedly 3tt~ch~d to the skull at the same IGfe~ lce position. U.S. Pat. No. 5,176,689 to Hardy et. al. and U.S. Pat. No.
4,923,459 to Nambu, describe app~us that are attached to the skull to ~ h ...;ne the location and SizG of tumors. However, the app&.~lus in Hardy and Nambu also can not be det~rh~ and acculdlely re~tt~hed to the skull at the same ,.,f~l~,nce location.
TherGfore, the appalatus described in Newell, Hardy, and Nambu are not useful insolving the problems of time and cost that presei.tly exist with loc~ g lesions before p~fol...il,g stereotactic surgical procedures.
SUB~ 111 IJT~ SHEET (RULE 26) wo 94123C63 2 16 0 6 65 PCT/US94/02718 -SUMMARY OF THE INVENTION
It is, the~cfol." an object of the invention to reduce the time and cost of localizing intracranial targets before each fractionated stereotactic radiation therapy session.
Another object of the invention is to increase the accuracy in reAn~ching a sl~,r~otactic frame to a skull at the same reference location in relation to the skull.
A further object of the invention is to increase the variety of stereotactic radiosurgical procedures that can be performed on a patient.
The invention is a system for ~.rol.,ling ~lelcotactic radiosurgical procedures upon a target within a skull. The system comprises a rigid frame that is positioned around the skull to define a multi-ll;.,.c ncional coordinate system. Multiple arms are coupled to the frame, each arm having an ~nArhm~nt assembly that is movable along a longitudin~l axis directed subs~ iAlly toward the center of the rigid frame assembly. Multiple receptors are either Ittach~d to the skull or drilled into the skull for receiving an ~CSoci~trd ~tt:ln~ Cn~ Ac5e...bly. The ~ceptol~ provide a n-o~ ing base upon which the frarne can be repe:~tedly ~ttArhed and det~rh~d from the skull at the sarne reproducible reference loc;~ti- n A drill and tap are slidably ~ttnch:~ble to any one of the arms along the same longitudin:~l axis as the ~csoci~ted ~ttacl~ -t assembly. The drill is used for drilling a bore in the skull at each receptor location and the tap is used to form an intern~l screw thread in such a bore. An insertion mechAnicm is then slidably ~tt~rh~d to the arms to insert a l~,ceplor into the bore.
Each arm has a multi-station receptacle that receives the various ~tt~rhmpntc used for mounting and ~tt~r-hing the receptors. Special bushings are insertable inside the arm receptacles to hold the skull mounting devices along a single ~ u~ling axis sulu~ tiAlly perpe-ndic~ r with the longitudin~l axis of the associated arm. A
locking ...rchAnicm is used to lock the Att~chmPnt assembly in a preset longitu(linAl position in relation to the arm. The locked ~ttArhmrnt assembly can then be removed from the arm allowing the frame to be removed from the skull while l"Aint~;njng frame position information.
SlJBSTITl)TE ~HEET (RULE 26) 216066~
wo 94t236C3 ~ ' ;' pcrtus94tO2718 The invention is used in stereotactic radio~urge,y processes in the following manner. The ~ ,otactic frame is first attached to the skull and holes drilled at the locations where the frame mounts to the skull. Receptors are then instAlled into the skull holes and the frame re~tt,acllPd to the recepto,~ thereby locating it about the skull at a given reference position. The lesion is then loc~li7ed according to the frame .cfelcnce position and a stereotactic radiosurgical procedure pe.rol,l,ed. After the ~,.colActic radiosurgical procedure, the frame is removed leaving the lcccl)lol~~ttached in the skull holes. Before the next stereotactic surgical procedure, the frame is re~tArhrd in the ,cceptc"~ at the same reference position. ~lt~rn~tively, the holes drilled in the skull are used as receptors and the frame ~ttarhed directly into the drilled holes.
The lesion is loc~li7~d by deriving a set of coordinates relative to the frame reference position. Since the frame is re~tt~rh~d to the skull in the same position, the same lesion coordinates are used for each subse~ue-nt stereotArtic radiosurgicalprocedure. Having the capability to reuse the same lesion coordinates allow subsequent radiosurgical procedures to be pc.l~,llled without having to completely reloc~li7e the lesion. Thus, the cost and time of each therapy session is ~cJuGed The fo,~ing and other objects, l~atul~s and advantages of the invention will beco~lle more readily app~,nt from the following det~iled desc,iption of a p.e~,~d embodiment of the invention which proceeds with reference to the acco,ll~ ying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. I is a side view of a stereotactic frame acco,ding to the invention rhed to conventional radiation appa-~tus which may be employed for stereotactic radiosurge,y.
FIG. 2 is a front view of the ~ otactic frame shown in FIG. 1.
FIG. 3 is an enlarged side view of a front arm for the stereotactic frame shown in FIG. 1.
FIG. 4 is an enlarged side view of a rear arm for the stereotactic frarne shown in FIG. 1.
FIG. 5 is an enlarged front view of the rear arm shown in FIG. 4.
SUB~ 1~ I IJTE SHEET (RULE 26) wo g4n3~ 2 1 6 0 g ~ PCTrUSs4/02718 FIG. 6 is a view taken along line 6-6 in FIG. 5.
FIG. 7 is a cross-sectional side view of a clamp assembly.
FIG. 8 is a view taken along line 8-8 in FIG. 7.
FIG. 9 is a side view of a drill assembly.
FIG. 10 is a side view of a tap assembly.
FIG. 11 is a side view of an insertion assembly.
FIG. 12 is a side view of an ~tt~rhmrllt assembly.
FIG. 13 is a view taken along line 13-13 in FIG. 12.
FIG. 14 is an enlarged cross-section of the r~ceplor shown in FIG. 12.
FIG. 15 is a side view of the ~n~rhm~nt assembly in a locked position.
FIG. 16 is a view taken along line 16-16 in FIG. 15.
FIG. 17 is a side view of the ~tt~rllment assembly shown in FIG. 15 removed from the frame arm.
FIG. 18 is a side view of the ~tt~rhmrnt assembly shown in FIG. 12 inserted directly into a skull hole.
FIG. 19 is a view of an alternate embodiment of a l~eeplol.
FIG. 20 is an enlarged top view of the leceplor of FIG. 19.
FlG. 21 is a view taken along line 21-21 in FIG. 20.
DETAILED DESCRIPTION
FIG. 1 is a side view of a ~ iotactic frame 18 according to the invention ~tt~rhed to a gantry 14 of a conventional radiation appal~us, such as a linear accelerator. The plefe.l~d embo liment of the invention is shown and described herein in conjunction with a linear accelerator. The method and app~alus of the present invention can be equally well impleme~tçd with several brain u~apping techniques for loc~li7ing and defining targets such as angiography, CT sç~nning, MRI
(m~etiC reson ~nc~ ima~ng) and PET (positron emission tomogMphy). The linear accelerator in FIG. 1 is used for stereotactic radiosurgery and fractionated radiation theMpy on intracranial lesions inside a skull 12. A collim~tor 17 is ~tt~rhed by a SuppGIl arm 16 to the gantry 14. The gantry 14 carries the radiatior, ell~illingcollimator 17 in an arc around the skull 12. The frame 18 (ring) has a circular outside surface that mounts inside a circular bracket 24. In the present embodim~-nt of the SUBSTITUTE SHEET (RU~E 26) ~ ' ~ 94n3663 2 ~ 6 ~ ~ ~ 5 PCT/US94/02718 invention, ring 18 is commercially available Bracket 24 is ~tt~hed to a floor-stand (not shown) Arms 20 and 22 attach the ring 18 to the skull 12 Stereotactic radioslllge"/ procedures for identifying and destroying inner cranial lesions, are well known to those skilled in the art and, the,~folt;, will not be described in detail A specific procedure and apps~ulus for performing stereotactic radiosulgcl~ is described in U S. Pat. No. 5,027,818 to Bova.
The first step in the stereotactic radiosurgery process is loc~li7SItion of the lesion (e.g., tumor). One method of loc~li7~ion is CT and involves fitting the skull 12 inside a stereotactic frame 18 as illustrated in FIG. 1. A stereotactic localizing device is then ~t~clled to the frame. The subsequent brain mapping and target definition produces precise, x, y, z, coordinates of the target (to an accuracy of less than 1/2 millimeter) relative to the stereotactic frarne.
The patient is aligned in the gantry li and contiguous slices, beginning at the level of the ring 18 and advancing superiorly past the top of the patient's skull 12, are o~t~ned. If the target volume is identified in the coll")ule.ized tomography image, the x, y, _, coordinates of the target volume are again recalculated to provide a double check of the x, y, z, coordinates previously derived relative to the stereotactic ring 18.
The cr scan provides three dimensional anatomical information of the patient that allows a solid patient model to be constructed.
The data from the CI' scan, angiographic films and/or MRI is then transferred to a collmle.~cially available dosin-F tl y co~ ,ul~r system (not shown). For high single fractions of radiation to be delivered to the target volume, the radiation source emitted from collim~tor 17 is moved through multiple arcs around the skùll 12. For the radiotherapist and neuro~ul~;~on to be able to ex~mine the consequence of each portion of the arc prior to radiating the patient, the dosimetry system displays each arc se~,lllent on a computer screen. If any particular arc results in an extensive dose of radiation to a critical structure inside the brain, the therapist alters the arc parameters to avoid the anatomical area of concern. Once the acceptable radiation ~...ent schelne has been derived, the coordinates of the isocenter (focal point of the radiation beam), the collimator coordin~tes, and the arc parameters are transferred to theradiation app~lus 14 and the radiation administered to the patient.
SUBS~ITUTE SHEET (RULE 26) .2160.6'65 wo 94n3663 PCT/US94/02718 --As explained above, the target coordinates are ~enel~ted relative to the frarne 18. The~fGle, moving the ring 18 in relation to the skull 12 would cause the radiation beam focal point to be misaligned with the target location. To prevent focal point misalignm~nt, conventional stereotactic rings are kept on during the entire loc:~li7~tion process. In addition, due to the extensive time re(luirel~ents required for all of the loc~li7:~tion procedures described above, fr~ctiol-~ted stereotactic radiation therapy is not tAtel,sively ~II~"I,ed.
In the present invention, however, the arms 20 and 22 can be det~rhP-d from the skull 12 and re~tt~rhed to the skull 12 at the sarne reference location. This repe:-tnble positioning of ring 18 at the same x, y, z coordinates in relation to the skull allow the radiation app~lus 14 to use the same coordinates for each radiation therapy session. The ring 18 can also be removed between various loc~li7~tion procedures, for example, while the physician computes and optimizes radiation doses.
To explain further, FIG.2 shows a front view of the sl~.~,otactic ring 18 shown in FIG. l . The ring 18 is seated inside the bracket 24 and has four arms 20, 22, 26, and 28 ext~nrling along a longitu~lin~l axis sul,sl ~uti~lly parallel with the center axis of the ring 18. Each arm is ~tt~rhed to the skull 12 by an ~tt~rl""~.~t assembly 30. The .~.t~ l""f 1" assembly sits in a l~,ceptor 32 residing in the skull 12.
The arms are positioned so that the att:l~ h...f ~-~ assembly 30 co~t~rtc with skull 12 in a direction subsl;~ti~lly pe~en~ic~ r with the t~ngenti~l plane passing through the skull contact point.
For example, front arms 20 and 26 are angled toward each other slightly more than rear arms 22 and 28 to ~ccolmt for the inclined surfaces on the front of skull 12.
The rear arms 22 and 28 are less angled to provide perpe~ icul:~r contact with the ~u~ nti~lly round surface at the back of skull 12. The perpendicular contact of each ~tt~chm~nt assembly 30 allows a m~imum amount of skull bone to surround each receptor 32. By m~ximi7ing the amount of skull bone surroun~ing each receptor, the stability in which the receptor 32 is seated in the skull is increased. As will later be more fully described, the arms are detsu l1~hle from ring 18. This feature permits ~tt~h.,.f nt of the two types of arms, arms 20,26, on the one hand, and arms 28, 30, to dir~.~,nt locations on the ring to accommodate differently shaped skulls.
.~' L .. ~
SUBSTITUTE SHEEr (~ E 26) 21 6~0 6 B5 ~/US94/02718 Similarly, different numbers of each type of arm may be used up to and including all of the arms being of one type or the other.
The l.,CGplO~ provide a stable mounting foundation for each :Itt~rhmPnt assembly 30 and allow the ring 18 to be :ltt~rhrd and det~rhr-d from the skull at a reproducible reference location. For example, the attachment assembly 30 is removable from the frame arm to allow the ring 18 to be removed from the skull 12.
However, keeping the receptors 32 in the skull allow each ~n~rhment assembly 30 to be reseated in an associated receptor 32 at the previously defined reference location.
Thus, the ring 18 can be repeatably repositioned in the same location in relation to the skull 12. A series of skull processing procedures are performed on skull 12 before inserting ~Gceplol j 32 and are described in detail below.
FIG.3 is a side view of the front arm 20 and FIG.4 is a side view of the rear arm 22 shown in FIG. 1. Both the front and rear arms have a shaft 40 with oppositely inclining sides 34. The front arm 20 has a rotated assembly section 44 that is skewed in relation to the shaft 40. In Fig.4, the assembly section 45 is aligned with shaft 40.
Both the front and back arms have equal di~ te~ bushing holes 36 and equal di~mPt~.r lock screw holes 38. The shaft 40 of rear arm 22 is shown inserted into the ring 18.
FIG.5 is a front view of the rear arrn 22 shown in FIG.4. The shaft of each front and back arm has a set of female conical bores 46 for receiving a screw 48through a hole in ring 18. FIG. 6 is a cross-section of the ring 18 and arm 22 shown in FIG.5. A dovetail slot in ring 18 receives the shaft 40 of arm 22. The applo~liate conical bore 46 (FIG. 5) is aligned with the ring hole 50 according to the size of the patient's skull and lesion location. Ring hole 50 has internal threads that interlock with tLhe threads of screw 48. Thus, rotating screw 48 into hole 50 forces the conical tip of screw 48 against the conical bore 46. The tip of screw 48 forces shaft 40against the back face of the dovetail slot holding arm 22 securely in the ring 18.
F~G.7 is a side view of a clamp assembly 52 and FIG. 8 is a view taken along line 8-8 in FIG.7. A clamp bushing 54 is insertable inside hole 36 (see FIG.5). The bushing 54 has an internal threaded hole that receives and interlocks with the threads of clarnp shaft 56. The front end of clamp shaft 56 is coupled to a swiveled clamping mount 58 and the rear end of clamp shaft 56 is ~tt~rhed to a crank 60. The bu~hing SUBS I 1~ lJTE SHEET (RULE 26) wo 94/23CC3 2 1 6 0 6' 6 5 PCT~S94/02718 ~
54 is locked to the arm 22 by a lock screw 62. The threads of lock screw 62 engage with the internal threads of hole 38 (see FIG. 5) and hold a flange 66 on bushing 54 against the rear face of arm 22. Lock screw 62 allows quick insertion and extraction of various buchingc from hole 36, however, alternative ~ttz~ nt ~..PÇI~niCmC could also be used to attach various app~atus to arm 22.
The clamp assembly 52 is used to initially attach the ring 18 and arms 20,22, 26, and 28 to the skull 12 and is inct~lled by inserting bushing 54 into hole 36. A slot 64 in bushing 54 (FIG.8) is positioned to pass around lock screw 62. Bushing 54 is then rotated so that flange 66 slides underneath lock screw 62. Lock screw 62 is then screwed further into hole 38 pressing against the flange 66 and holding the bushing 54 firmly against arm 22.
Rotating crank 60 moves crank rod 56 forward pushing mount 58 against skin 67 of skull 12. The mount 58 swivels slightly as it presses against the skull 12 so that the front face of mount 58 lies flat against the skull. Each of the four ;~tt~ck...~nt assemblies (i.e., one for each arm) are tight~r ed until the frame is securely f~ct~ned to the skull 12. The clamp assembly 52 is removed from arm 22 by ul~s~ ving lock screw 62 and rotating flange 66 out from under lock screw 62. Notch 64 is then centel~d about lock screw 62 and bushing 54 removed from hole 36. The clamp assembly 52 shown in FIG. 7 is identi~l for each frame arm and provides support for the frame during the subsequent drilling and ~ rllm~nt p.vcesses desçribed below.
FIG. 9 is a side view of a drill assembly 68. The drill assembly inchldes a drill bushing 74 insertable into hole 36 of arm 22, a drill 70, and a drill bit 72. The drill bushing 74 is ~n~rh~d to arm 22 by lock screw 62 in the same ~ ner as clarnp asse,--bly 52 in FIG.7.
The drill assembly 68 is used for boring holes into skull 12. The skull holes are drilled one at a time by first removing one of the clamp assemblies 52 as described above in FIG.7. A drill bushing 74 is then inserted and locked into hole 36 and drill 70 enabled so that drill bit 72 begins boring a hole 76 into skull 12. After boring hole 76, drill bit 72 is removed from the skull 12 and the drill assembly 68 removed from arm 22. The drill assembly is also removed from arm 22 in the same manner as clamp assembly 52 (see FIG.7). Various drill bits can be utilized to create different skull holes. Different di~meter drill bits require different bushings having SUB~ 111 lJTE SHEET (RULE 26) wog4/23663 216066~; PCT/US94tO2718 different-sized bores therein for receiving the bit. Preferably, the clearance btl~ce the bit and the bushing hole is approximately .01 mm. The type of holes drilled in skull 12 depend on the type of receptors inserted into the skull.
FIG.10 is a side view of a tap assembly 78 which includes a tap bushing 80 insertable into hole 36 of arm 22. The tap bushing 80 receives a tap bit 82 that is 3~h 3ble to a tap chuck 83. The tap assel,.bly 78 is ~tt:~rhed and det73chpd from arm 22 in the same manner as the clamp and drill 3cs~ blies 52 and 68,1espccli~ely, as previously described above. The tap assembly is used to tap threads in the hole 76 previously drilled by drill bit 72 (FIG.9). However, if a non-threaded receptor or a self-threading receptor is used, tap assembly 78 is not necess~3~ y.
FIG. l l is a side view of an insertion assembly 84 which includes a shaft 88 coupled at the front end to a wrench fitting 92 and is coupled at the rear end to a crank 90. The shaft 88 is held by the same bushing 80 used in tap assembly 78 (FIG.
10). The wrench fitting 92 is insertable into an internal socket in ,~,ceptor 32. After the tap bit 82 is removed from bushing 80, shaft 88 is inserted into bushing 80 and receptor 32 :ltt 3nhed to the wrench fitting 92. Crank 90 is then rotated c~3ucirlg es~rn~l threads on l~ceptor 32 to interlock with the int~rn 31 threads in skull hole 76.
The r~~l)tor 32 is screwed tightly into hole 76 so the receptor can support frame 18.
FIG.12 is a side view of the ~tt~rl....~ asselllbly 30 shown in FIG. 2 and FIG. 13 is a view taken along line 13-13 in FIG. 12. The 5~11731'~ assembly inrludes a screw pin 95 insertable into a screw pin bushing 102. The screw pin 95 has a lockable head 96 at the rear end with a notch 97, a threaded midsection 98 that interlocks with the il~tern~l threads of the screw pin bushing 102, and a tapered tip 100 at the front end. The rear face of screw pin bushing 102 has four screw holes 104 (~G.13) used in coo~ination with a lock washer as will be described in further detail below in FIGS.15 and 16.
The ~tt7lchm~0nt assembly 30 is again inserted and e~ ed from arm hole 36 in the same manner as the clarnp, drill, and tap assemblies. After the insertionassembly 84 (FIG.11) is removed from arrn 22, screw pin bushing 102 is inserted and locked into hole 36. Screw pin 95 is then rotated with a screw driver (not shown) into bushing 102. Bushing 102 has a close tolerance bearing bore on each end to guidethe screw pin 95 repe-~t~bly regardless of the insertion di~t~nce into bushing 102. The SUBSTITUTE SHEET (RULE 26) 2i6066~
Wo 94n3663 pcrnJS94/02718 bore on the left receives the shaft of pin 95 while the bore on the right receives head 96. Between the bearing bores in bushing 102 is a threaded section which engageswith external thread 98 on screw pin 95 thus allowing screw pin 95 to be driven forward. As screw pin 95 moves forward in the buching 102, tapered tip 100 is forced into the socket of receptor 32. Screw pin 95 is sufficiently tight~-ned against receptor 32 so that the frame 18 (FIG. I) can not be inadve,t~.ntly ~licmounted from the receptors or moved in relation to skull 12.
FIG. 14 is a cross-section of the receptor 32 shown in FIG. 12. The socket inside receptor 32 col~",l,ses a wrench receiving section 106 and a screw pin receiving section 108. Section 106 is used for receiving the wrench fitting 92 of insertion assembly 84 (FIG. 11) and section 108 receives the tapered tip 100 of screw pin 95 (FIG. 12). While inserting ~. ceplor 32 in the skull (see FIG. 11), the wrench fitting 92 interlocks inside section 106, allowing the receptor to be screwed into the skull hole 76. After the ,~ce~tor is securely f~ct~n~od into the skull, the screw pin 95 is inserted into the 1~ ceptor 32 pressing the tapered tip 100 of screw pin 95 against the interior walls of section 108.
FIG. 15 is a side view of screw pin 95 locked to the screw pin bushing 102 by a lock washer 112. The lock washer 112 is held to bushing 102 by a screw 110. FIG.
16 is a front view of the lock washer 112 shown in FIG. 15. The lock washer 112 has a finger 116 that rides inside the notch 118 (in Fig. 13) in screw pin 95. Screw 110 is insertable through lock washer slot 114 into any one of the screw pin bushing holes 104.
After the screw pin 95 has been inserted sllffit~i~ntly into the receptor 32 (FIG.
12), lock washer 112 is slid over the head 96 of screw pin 95 as the lock washerfinger 116 rides inside screw pin notch 118. When the lock washer 112 lies flat against the rear face of bushing 102, screw 110 is inserted into the hole 104 that happens to be access;ble through lock washer slot 114. If l-f cess:~ y, lock washer 112 can be slid off of pin 95 and turned over to place slot 114 in a location relative to one of holes 104 to permit in~t~ tion of screw 110 as shown in FIG. 16. Screw 110 isthen tightPned clamping lock washer 112 against the rear face of bushing 102. The lock washer 112, when tight~ned to bushing 102 by screw 110, prevents screw pin 95 from rotating inside bushing 102. Thus, the lateral position of the arm 22 is locked at SUB~ T~ SHEET (RULE 26) 2iB0665 wo 94n3663 PCT/US94/02718 its present location which conctit~ltes the frame ,cr.,l~nce position.
FIG. 17 is a side view of the ~tt:l~hm~nt assembly 30 shown in FIG. 15 removed from the frame arm 22. To remove the frame from the patients skull, the ~n~rhmçnt assembly 30 must be removed from arm 22. However, it is nccessr.. y that the same lateral screw pin position be used when the frame is re~tt~rh~d to the skull 12. The.cfo~" the entire locked s-tt~rh...f nt assembly 30 is removed from arm 22 so that the screw pin position is 1,.%;nts.il~
For example, to remove the frame 18 from skull 12, the screw pin bushing 102 is first removed from arm 22. Bushing 102 is removed by unscrewing lock screw 62from arm 22 then rotating bushing 102 counlel-clockwise until flange 66 no longer resides under lock screw 62. Notch 64 in bushing 102 (FIG. 8) is then centc.Gd around lock screw 62 and the bushing 102 e~llacled from arm hole 36. The ~tt~hm~nt assemblies for the ~ g three arms 20,26, and 30 are removed in thesame fashion. The frame is then lifted up over the skull 12.
It is illl~ ;Ult to note that the ~t~rhm~nt assembly 30 l~lllaih~s in the lockedposition shown in FIG. 17 throughout the Sl~ o~ tic r~dios...~,e"~ process. Thus, the lateral position of frame 18 in relation to skull 12 ~c~ ns intact. In addition, the longitu(iin~l and l~tituAinFll positions of the frame in relation to the skull are preserved by the IGceplul~ 32 that remain ~tt~ched in the skull in between M~ tion seS~ionc.
Thus, the same frame position in relation to the skull 12 can be repeatably ob~ ed by reinserting the locked ~tt~-k-.-~nt assemblies 30 back into the ~ccoci~t~d arms and reclamping the screw pin bushing 102 with the lock screw 62. As long as the ~tt~rh.~ t assembly remains in the locked position shown in FIG. 17, the frame can be removed and reS~tt~rhed to the skull as many times as dictated by the stereotactic radiation therapy.
After completion of the radiation therapy, the lock washer 112 is det~h~d from bushing 102 and the ~tt~hn.~nt assembly 30 used for another patient. A frame ring 18 and a set of frame arms can be allocated for a single patient over the duration of the radiation l~ or, alle..,atively, the same ring and arms can be used by multiple patients by readjusting the arms for each p:~ti~nt~ skull dim~n~ions (see FIG.
5). It is illlpollânl to identify each arm and record the mounting location for each arm on ring 18 as well as the bore, like bores 46 in FIG. 5, used to mount the arm on the SUB~J~JLITE S~EET ~RULE 26) 216~665 wo 94n3663 K:T/US94/02718 -ring. This ensures that the entire frame is acculately l~ cse~hled when additional fractionated radiosurgery is to he pelrolllled. If multiple p~tientC share the same frame, a set of individual ~tt~hm~ont assemblies 30 are ~ tQined for each patient.
It is important to note that all clamping, drilling, tapping, insertion, and ~tt~ h~ nt assemblies reside along a single longitudin~l axis. ~int:~ining a single longitudinal axis ensure that the screw pins attach symmetrically inside the receptor socket and increase frame stability.
FIG. 18 is a side view of the ~tt:~chm~nt assembly 30 shown in FIG. 12 inserted directly into a skull hole 120. In another embodiment of the invention, the frame can be ~tt~hf d directly into skull hole 120. The process for ~ rh;nf~ theframe to the skull is identicSIl to the process described above except that the drilling procedure (~IG. 9) is pelr(,l,-,ed such that the skull hole 120 is tapered to receive the conical tip 100 of screw pin 95. The tapping and ,~ceplor insertion procedures are then no longer l~luil~d. The lateral coo~inates of the frame are pre~rved by thelocked ~tt ~ .t a~se",bly 102, and the lon~itu~in~l and l:ltitu~in~l coordinates of the frame are preserved by the locations of the drilled skull holes 120 that remain in the patient for the entire ~le,~olactic M~i~tion t~e~ nt The embodiment shown in PIG. 18 leaves a visually less obvious frame receptor in the patient's skull. The direct frame ~tt.~çk~..e~-t process also requires fewer steps to install the frame and requires fewer assemblies to initially attach the frame to the skull. Various skull hole, drill bit, and screw pin designs can be uhlized to perform the steps des~ribed above. ~lttorl ~te assemblies can also be incol~Gl~lt;d into the arm holes for other sl~-~,olactic radiosurgery procedures. All ~cse~blycol.,ponel,~ are pl~fc.~bly titanium for MRI and CT co",palibility except for the arms which are ~lu~ir.~ or plastic.
Rece~Jtol~ imbedded in the skull are superior to bore cavities bored into the bone surface. Repe~ted frame/pin ~ttz~l"llf n~ Uil~S a relatively hard surface.
The overall process for using the stereotactic frame according to the invention is now des~ribed The frame arms 20,22, 26, and 28 (FIG. 2) are first adjusted inring 18 acco~ding to the size of the patients skull. The clamp assemblies 52 (FIG.7) are locked into the arm holes 36 and the clamps ~tt~ e d to the patients skull. After the clamps are tightened to the patients skull, one of the clamp assemblies 52 is SUB~ 11 1 IJTE SHEET (RULE 26) wo 94123C63 Pcr/uss4to2718 removed and replaced with the drill assembly 68 (FIG. 9). A hole is then drilled in the skull along the same axis as previously defined by the clamp assembly 52. After the hole is drilled in the skull, the drill assembly is removed, and if necessr~l y, the tap assembly 78 (FIG. 10) is inserted into the arm hole 36. After the skull hole is tapped, the tap assembly 78 is removed from the arm, and if required, the insertion assembly 84 (FIG. I 1 ) is inserted into the arm. The insertion assembly is used to insert a receptor 32 into the tapped skull hole and then removed from the frame arm. The ~nark...~l-t assembly 30 (FIG. 12) is then in~t~lled in the arm and the ~nslrhm~nt assembly screw pin 95 inserted into the receptor 32.
The above process is pe.l~ led for the ,~ ing three arms so that each arm has an associated ~n:lch~f nt assembly inst~lled in a receptor (see FIG. 2). Each ~tt~chment assembly screw pin 95 is then locked to the associated screw pin bushing 102 with a lock washer 112 and screw 110 as shown in FIG. 15. At this point, theframe 18 is securely ~tt~rhed to the skull and the loc~li7~tion process begins. After the initial loc~li7ation process and after the first radiation ~le~t,.~ , the frame may be e..lo~ed from the patient by uoscl~ g the lock screws 62 and removing each ~tt~çl""c~t assembly 30 from its arm (FIG. 17). The locked ~ l,",. .,~ asse,-lblies 30 are labeled and preserved for further t~ n.~ t~ on the patient. The patient carries the .~,cept~ 32 in his skull throughout the stereotactic r~ tion therapy.
At each ~ubse~uenl radiation therapy sescion~ the frame 18 is positioned around the p~t;eUl~ head and the locked ~n~rhment ~ccemhlies 30 reinserted into the ~CSOf i~ted arm holes 36. The ~tt~rk",lonl assemblies are then forced into the .eceplo.~ 32 by lock screw 62. The radiation therapy is then carried out withouthaving to relocali~ the target. After completion of the therapy session, the frame 18 is again removed and the :~ttzl~hm~nt acsemblies stored for the next radio~ulE ical session. Thus, fractionated stereotactic radiosurgery may be performed at a reasonable cost.
During the times between therapy sessions, .ecepto.~ 32 remain fixed in the p~tient~ skull and extend just above the surface of the skin as shown in Fig. 12. At the conclusion of the fractionated stereotactic radiosurgery according to the present invention, receptors 32 are unscrewed using assembly 84 as shown in FIG. 11. Theskin around the former location of the receptor is then closed and treated as n~ces~ry SUBS I I I LITE SHEET (RULE 26) WO 94n3c63 2 1 6 0 6 65 PCT/US94tO2718 to ensure satisfactory hç~ling.
Turning now to FIG. 19, illustrated therein is another embodiment of a ptor 130 which pe~ ls a similar function to ~ce~)lor 32 in FIG. 12. In the embodiment of FIG. 19 a drill assembly ( not shown) similar to drill assembly 68 in FIG. 9 is used to create a bore 132 in skull 12. The drill assembly is connt.cted to frame 18 in the l.,almer previously desclibed and a drill bit (also not shown) which is smaller than drill bit 72 in FIG. 9 is used to create bore 132.
Receptor 130 includes a lug 134 which is received in bore 132. Receptor 130 further includes a conical opening 136 which receives the lower portion of tapered tip 100 as shown in FIG. 19. The perimeter of receptor 130 includes a circular flange 138 having a pair of countersunk holes 140, 142 the.tth-~)ugh.
In use, a bore, like bore 132, is drilled as described above opposile each of the arms in frame 18. Next, a spot of glue is placed on lug 134 and/or in bore 132. When the lug is pressed into the bore, receptor 130 is firmly secured to skull 12 without requiring a larger bore to be drilled in the skull, as described in connçction with the emb~im~-nt of FIG. 11. In the event the glue is not sufficient to p~pell~/ secure receptor 130, ~dition~l small pilot holes can be drilled in skull 12 lhl~u~;ll holes 140, 142 in the ~ceptor to permit screws, like screws 144, 146 to be in~t~lled to secure the ~,ceplol to the skull. After inst~ tion, pin 95 is inct~lled with its ~csociated bushing (in FIG. 12) so that tip 100 is received in the receptor as shown in FIG. 19.
Having desclil,cd and illustrated the principles of the invention in a prefell~,d embodirn~nt thereof, it should be appa.ent that the invention can be modified inarr~ngernert and detail without dep&.ling from such principles. I claim all modific~tions and variation coming within the spirit and scope of the following clalms.
SUBSTITUTE SHEET ~RULE 26)
Claims (14)
1. A system for performing stereotactic radiosurgery upon a target within a skull, comprising:
a rigid frame for positioning around the skull defining a multi-dimensional coordinate system;
multiple receptors each attached to the skull, the receptors providing a mounting base upon which the frame can be repeatably attached to and detached from the skull at the same reproducible reference location;
multiple arms coupled to the frame;
attachment assemblies attached to each arm and movable along a longitudinal axis directed substantially toward the center of the rigid frame assembly into preset positions against the receptors, each of the attachment assemblies in the presetposition extending from the frame in an associated laterally extended condition;a locking device for locking each attachment assembly into its associated laterally extended condition; and means for removing the attachment assemblies from the receptors while said attachment assemblies remain locked in said associated laterally extended condition.
a rigid frame for positioning around the skull defining a multi-dimensional coordinate system;
multiple receptors each attached to the skull, the receptors providing a mounting base upon which the frame can be repeatably attached to and detached from the skull at the same reproducible reference location;
multiple arms coupled to the frame;
attachment assemblies attached to each arm and movable along a longitudinal axis directed substantially toward the center of the rigid frame assembly into preset positions against the receptors, each of the attachment assemblies in the presetposition extending from the frame in an associated laterally extended condition;a locking device for locking each attachment assembly into its associated laterally extended condition; and means for removing the attachment assemblies from the receptors while said attachment assemblies remain locked in said associated laterally extended condition.
2. The system according to claim 1 including a drill attachable to any one of the arms along the same longitudinal axis as the associated attachment assembly for drilling a bore in the skull at each receptor attachment location.
3. The system according to claim 2 including a tap attachable to any one of the arms along the same longitudinal axis as the associated attachment assembly, the tap forming an internal screw thread in such a bore.
4. The system according to claim 2 including an insertion mechanism attachable to any one of the arms along the same longitudinal axis as the associated attachment assembly for inserting a receptor into such a bore.
5. The system according to claim l wherein each attachment assembly arm has a multi-station receiving socket, the receiving socket located substantially over an associated receptor location and capable of receiving various equipment for mounting and attaching said receptor.
6. The system according to claim 1 wherein the arm attachment assembly is removable from the associated arm and lockable in a preset longitudinal position in relation to said arm, the locked attachment assembly maintaining frame position information after the frame is removed from the skull.
7. The system according to claim 1 wherein the receptors comprise circular screws insertable into the skull, each screw having a receptacle for retaining one end of an associated attachment assembly.
8 Apparatus for performing stereotactic radiosurgery upon a lesion within a skull, comprising:
a ring for positioning around the skull defining a multi-dimensional coordinate system for localizing surgical procedures;
multiple arms attached to the ring, each arm having a receptacle and elongated in a direction substantially parallel with the ring axis;
multiple skull mounting devices insertable into the arm receptacles, each device capable of performing a different function for mounting each arm on the skull, said mounting devices including a mounting pin for attaching the ring to the skull as a predetermined reference location; and multiple bushings insertable inside the arm receptacles for holding each skull mounting device along a single mounting axis substantially perpendicular with the longitudinal axis of the associated arm.
a ring for positioning around the skull defining a multi-dimensional coordinate system for localizing surgical procedures;
multiple arms attached to the ring, each arm having a receptacle and elongated in a direction substantially parallel with the ring axis;
multiple skull mounting devices insertable into the arm receptacles, each device capable of performing a different function for mounting each arm on the skull, said mounting devices including a mounting pin for attaching the ring to the skull as a predetermined reference location; and multiple bushings insertable inside the arm receptacles for holding each skull mounting device along a single mounting axis substantially perpendicular with the longitudinal axis of the associated arm.
9. The apparatus according to claim 8 wherein each arm is selectively attached to the ring at various positions along the arm longitudinal axis.
10. The apparatus according to claim 8 including means for locking the mounting pin to one of said bushings, the locking means allowing the pin to be mounted in the receptacle in the same location each time the ring structure is attached to the skull.
11. The apparatus according to claim 8 wherein the skull mounting devices include a drill bit for boring holes in the skull, the holes being co-axially aligned with the associated mounting axis.
17a
17a
12. The apparatus according to claim 8 wherein the skull mounting devices include a clamp for holding the ring to the skull.
13. The apparatus according to claim 11 including receptors insertable into the holes created by the drill bit.
14. The apparatus according to claim 8 including a bushing lock mechanism for repeatably locking each bushing into the arm receptacles at a bushing reference location.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US08/048,384 US5380336A (en) | 1993-04-16 | 1993-04-16 | Method and apparatus for stereotactic radiosurgery and fractionated radiation therapy |
| US08/048,384 | 1993-04-16 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2160665A1 CA2160665A1 (en) | 1994-10-27 |
| CA2160665C true CA2160665C (en) | 1999-03-23 |
Family
ID=21954288
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002160665A Expired - Fee Related CA2160665C (en) | 1993-04-16 | 1994-03-14 | Method and apparatus for stereotactic radiosurgery and fractionated radiation therapy |
Country Status (5)
| Country | Link |
|---|---|
| US (2) | US5380336A (en) |
| EP (1) | EP0746259A4 (en) |
| AU (1) | AU6550594A (en) |
| CA (1) | CA2160665C (en) |
| WO (1) | WO1994023663A1 (en) |
Families Citing this family (36)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5575794A (en) * | 1993-02-12 | 1996-11-19 | Walus; Richard L. | Tool for implanting a fiducial marker |
| US6096048A (en) * | 1994-04-20 | 2000-08-01 | Howard, Iii; Matthew A. | Noninvasive, reattachable skull fiducial marker system |
| US5588430A (en) * | 1995-02-14 | 1996-12-31 | University Of Florida Research Foundation, Inc. | Repeat fixation for frameless stereotactic procedure |
| DE19511796C2 (en) * | 1995-03-30 | 1998-10-01 | Siemens Ag | Head antenna for magnetic resonance examinations |
| DE19515550B4 (en) * | 1995-04-27 | 2004-06-03 | Gesellschaft Zur Errichtung Und Zum Betrieb Radioneurochirurgischer Behandlungszentren Mbh | Method and device for checking the positioning of a radiation spot |
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-
1993
- 1993-04-16 US US08/048,384 patent/US5380336A/en not_active Expired - Fee Related
-
1994
- 1994-03-14 WO PCT/US1994/002718 patent/WO1994023663A1/en not_active Application Discontinuation
- 1994-03-14 AU AU65505/94A patent/AU6550594A/en not_active Abandoned
- 1994-03-14 CA CA002160665A patent/CA2160665C/en not_active Expired - Fee Related
- 1994-03-14 EP EP94913284A patent/EP0746259A4/en not_active Withdrawn
- 1994-10-26 US US08/329,228 patent/US5634929A/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| EP0746259A4 (en) | 1997-05-21 |
| AU6550594A (en) | 1994-11-08 |
| EP0746259A1 (en) | 1996-12-11 |
| US5380336A (en) | 1995-01-10 |
| WO1994023663A1 (en) | 1994-10-27 |
| CA2160665A1 (en) | 1994-10-27 |
| US5634929A (en) | 1997-06-03 |
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