CA2201998A1 - Collimators - Google Patents
CollimatorsInfo
- Publication number
- CA2201998A1 CA2201998A1 CA002201998A CA2201998A CA2201998A1 CA 2201998 A1 CA2201998 A1 CA 2201998A1 CA 002201998 A CA002201998 A CA 002201998A CA 2201998 A CA2201998 A CA 2201998A CA 2201998 A1 CA2201998 A1 CA 2201998A1
- Authority
- CA
- Canada
- Prior art keywords
- radiation
- target
- collimator
- source
- impervious
- 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.)
- Abandoned
Links
Classifications
-
- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21K—TECHNIQUES FOR HANDLING PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
- G21K1/00—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating
- G21K1/02—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating using diaphragms, collimators
Abstract
A collimator for use in radiosurgery including material which is generally radiation impervious and which is configured to define at least one at least partially hollow radiation path.
A method is also provided for radiosurgery including the steps of providing an irradiating device including at least one source of radiation arranged to irradiate a target, and at least one collimator disposed between the at least one source of radiation and the target and including material which is generally radiation impervious and which is configured to define at least one at least partially hollow radiation path, producing radiation beams with the irradiating device, and directing the radiation beams at a target volume from a multiplicity of orientations.
A method is also provided for radiosurgery including the steps of providing an irradiating device including at least one source of radiation arranged to irradiate a target, and at least one collimator disposed between the at least one source of radiation and the target and including material which is generally radiation impervious and which is configured to define at least one at least partially hollow radiation path, producing radiation beams with the irradiating device, and directing the radiation beams at a target volume from a multiplicity of orientations.
Description
22ol998 COLLIMATORS
l D Oli Tl-IE INVl~Nl'ION
Tlle present invenfioll relates to radiosutgely genel-ally, and particulal-ly tocollimators used in stereotactic radios~n-~ery.
13ACKGROIJND Ol~ Tl IE INVENrrlON
Stereotactic ra~iosurgery invt)lves dose accu~ llatioll in a target volume by irradiating the target fi-om a multilllicity of orientations witll rlnely collimated beams.
rI lle use of stel-eotactic r~(liosur~ety to ren(ler tiss~le necrotic is well established an(l vario~ls systems are cul-l-elllly use(' s'or stereotactic ra(liosln~ely. The prior art recognizes the need to conline ra(lialion as mucll as possil)le to tl-e tat~et volullle being treated. Generation of a clesired dose l~attelll in an(l o~lt ortl-e tnl-L,et volulllc is Ille ol)jeclive of a treatnlent plall. Sucll a plan takes into accoutlt linlitatiolls of tl~e l~artic~llal- ra(lios~ ical system used. System lypes include a Gamllla Unit whicll utilizes a nlulfil~licity Or Cobalt-6() sources arl-al~ged on a spherical surface, a linear accelerator (I,INAC) wl~ich ufili~es a proton bealll source nlounte(l on a rotating gantry, and a stationary genel-alol- lor a cl-arge(J l)arlicles bealll. l'llese radioslll-gical systems, as well as associated metllods, cllalaclcl-istics an(l l~erforlllallce al-e described in various publicafiolls, e.g., Stereotactic Racliosul ~ery, Alexan(lel- E. el al.7 McGraw-l-lill, 19~)3, and Neul oslJI-L~ery Clin s o~Nortll America, vol. ~, no. 1, L utlsfol(l l, D. (e(litor), W.13. S~l~ln(lers Co., Jan. 1992.
Treatlllellt ~!anllill~ capabililies inclu(le selectin~ a dose level to the tar~set, choosing cnllinlatols for bealll s}la~in~ al1(1 a detern~inatioll of l-eam orientations fi-om whicll ra{iialion is deposited in tlle target vol~ln-e. ln or~ler to re(lLIce tl~e (lose deposite(l in llealtlly tissue outside the target vol~lme, it is generally desiral~le to spl-ea(l beam orientations over a wide range and to employ collinlators wllicl~ conl;lle tlle ra(liatioll to t}le targel vol~nlle.
Pl-ior art stere(-)tactic radio.ciulgel-y systems incolpol-ate point soul-ces for generatillg radiation l~ealns (a lloinl soln-ce is a ra(lialioll source wllicll is signilicantly smaller than the tar~et). A collimator associated witll a }~oin~ sourGe pl~od~lces a divelging beam, i.e., the beasn widtll increases witll inclease(l (lislance l'lonl the soulce. ~ucll a diverging collimator~ ortlle type used in conjullcti~ witll a l lNAC or ~itll a (Janlllla Unit, is nla(le of a radiatioll inlpervious material configured to define a divel-~,illg ra(liation patll.
22nlgg8 The collimators associated with prior art stereotactic radiosurgery systems -incorporate clear (non-blocked) radiation paths. The intensity of a radiation beam produced by such a clear path collimator, in any plane perpendicular to the beam axis, decreases monotonically with radial distance from the axis. One of the consequences of such a beam profile is that prior art stereotactic radiosurgery methods are restricted for treating targets smaller than about 50 millimeters in diameter. The apparent reason is the increased radiation to healthy tissue.
SUMMARY OF THE INVENTION
The present invention seeks to provide improved apparatus and techniques for radiosurgery which represent a radical departure from the prior art.
The present invention includes a hollow path collimator, diverging or converging, which is capable of producing a hollow radiation beam at the target, thus providing an ability to irradiate mainly the target boundary. Causing tissue to be necrotic by irradiation mainly at the target boundary may have adequate clinical results while reducing the radiation dosage to healthy tissue. The prior art does not describe a collimator for stereotactic radiosurgery incorporating a hollow radiation path.
The prior art does not describe a stereotactic radiosurgery system utili~in~ a converging collimator, i.e., one with a converging radiation path. In the present invention, a converging collimator may be used to produce a hollow radiation path.
The prior art does not describe a system ~Itili~ing an area source for generating radiation beams for stereotactic radiosurgery. An area source or a large source is a radiation source which is comparable in size or larger than the target. An area source, e.g., a Co-60 pack used for conventional radiotherapy, could be much cheaper for stereotactic radiosurgery than a LINAC or an array of 201 sources incorporated in the Gamma Unit.
In the present invention, a hollow radiation path collimator may be used to reduce the penumbra associated with a radiation beam produced by an area source. Since a single hollow radiation path reduces also the beam intensity (by blocking an internal portion of the beam), it may be advantageous to incorporate several hollow radiation paths in a single collimator.
However, increasing the number of radiation paths may also increase the penumbra, suggesting that a desirable compromise between increasing beam intensity and increasing penumbra be reached. Such a compromise, for a given source and a given collimator material, may be obtained ~y selecting optimally the number of hollow paths and the associated geometrical properties. The prior art does not describe the use of an area source and a collimator incorporating one or more hollow paths for stereotactic radiosurgery.
There is thus provided in accordance with a prerel~ed embodiment of the present invention, a collimator for use in radiosurgery including material which is generally radiation impervious and which is configured to define at least one at least partially hollow radiation path.
In accordance with a prerell ed embodiment of the present invention, the collimator further includes a shield which is generally radiation impervious, the shield having formed therein a beam passageway, and at least one beam blocker which is generally radiation impervious, the at least one beam blocker being located in the beam passageway so as to form the at least one at least partially hollow radiation path.
There is also provided in accordance with a p~ ed embodiment of the present invention, a collimator for use in radiosurgery including material which is generally radiation impervious and which is configured to define a converging radiation path.
There is also provided in accordance with a preferred embodiment of the present invention, an irr~ ting device for use in radiosurgery including at least one source of radiation arranged to irradiate a target, and at least one collimator disposed between the at least one source of radiation and the target and including material which is generally radiation impervious and which is configured to define at least one at least partially hollow radiation path.
In accordance with a preferred embodiment of the present invention, the at leastone collimator includes a shield which is generally radiation impervious, the shield having formed therein a beam passageway, and at least one beam blocker which is generally radiation impervious, the at least one beam blocker being located in the beam passageway so as to form the at least one at least partially hollow radiation path.
There is also provided in accordance with a preferred embodiment of the present invention, an irradiating device for use in radiosurgery including at least one source of radiation arranged to irradiate a target, and at least one collimator disposed between the at least one source of radiation and the target and including material which is generally radiation impervious and which is configured to define at least one converging radiation path.
2201g98 - There is also provided in accordance with a preferred embodiment of the present ~invention, a method for radiosurgery including the steps of providing an irradiating device including at least one source of radiation arranged to irradiate a target, and at least one collimator disposed between the at least one source of radiation and the target and including material which is generally radiation impervious and which is configured to define at least one at least partially hollow radiation path, producing radiation beams with the irra~iatin3~ device, and directing the radiation beams at a target volume from a multiplicity of orientations.
There is also provided in accordance with a pl~relled embodiment of the present invention, a method for radiosurgery including the steps of providing an irradiating device including at least one source of radiation arranged to irradiate a target, and at least one collimator disposed between the at least one source of radiation and the target and including material which is generally radiation impervious and which is configured to define at least one converging radiation path, producing radiation beams with the irradiatinQ; device, and directing the radiation beams at a target volume from a multiplicity of orientations.
There is also provided in accordance with a preferred embodiment of the present invention, a method for radiosurgery including the steps of providing at least one radiation source, collimating radiation from the at least one source to produce radiation beams which are at least partially hollow at the location of a target, and directing the at least partially hollow radiation beams at the target from a multiplicity of orientations to produce a radiation dose pattern having a substantially higher dose level at the boundary of the target and a substantially lower dose level at the interior of the target.
In accordance with a preferred embodiment of the present invention, the method further includes the steps of collim~ting radiation from the at least one source to produce non-hollow radiation beams at the location of the target, and directing the non-hollow radiation beams at the target from a multiplicity of orientations to produce an additional radiation dose pattern having a substantially higher dose level at the interior of the target and a substantially lower dose level at the boundary of the target.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be understood and appreciated more fully from the following detailed description, taken in conjunction with the drawings in which:
Fig. 1 A is an illustration of a prior art radiation collimator;
Figs. lB, lC and lD illustrate three radiation collimators, constructed and operative in accordance with three alternative preferred embodiments of the present invention;
and Figs. 2A, 2B and 2C are illustrations of three di~lellt cross beam profile configurations of radially symmetric beams in planes perpendicular to the corresponding beam axis;
wherein Fig. 2A illustrates a non-hollow cross beam profile produced either by aprior art collimator according to Fig. lA, a collimator of the present invention according to Fig.
lC or a collimator of the present invention according to Fig. lD, at its focus;
Fig. 2B illustrates a hollow cross beam profile produced either by a collimator of the present invention according to Fig. lB, or a collimator of the present invention according to Fig. lD at a distance from its focus; and Fig. 2C illustrates a superposition of a hollow beam profile and a non-hollow beam profile.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Reference is now made to Fig. lA, which illustrates a prior art radiation collimator, and to Figs. lB, lC and lD which illustrate three alternative embodiments of radiation collimators constructed and operative in accordance with a pre~ell~d embodiment of the present invention. The radiation collimators of Figs. lA - lD are characterized in that they are formed of material which is generally radiation impervious. The radiation collimator shown in Fig.
lA is configured to define a non-hollow and diverging radiation pathway. Radiation collimators shown in Figs. lB and lD are configured to define an at least partially hollow radiation path. The radiation collimator shown in Fig. lC is configured to define a non-hollow and converging radiation pathway.
The hollow radiation path is useful for precise radiation treatment of targets in accordance with a preferred embodiment of the present invention whereby it is desired to irradiate the periphery of the target without substantially irr~ ting the center thereof~ or whereby it is desired to irradiate a target using a large source of radiation. It is noted that throughout the specification and claims, the terms large source of radiation and small source of radiation refer to 22~
~he relative size of the radiation source compared to the size of the irradiated target. A large ~ source of radiation is comparable in size or larger than the target, while a small source of radiation is significantly smaller than the target.
Fig. lA illustrates a collimator assembly including an exterior shield 10 defining a location 12 for a source of radiation, indicated by reference numeral 14. The exterior shield 10 is formed with a bore 16 extending outwardly from location 12. Preferably a collim~ting unit 20 is disposed in the bore 16.
In the embodiment of Fig. 1A, the collim~ting unit 20 defines an unblocked diverging radiation beam pathway. It is noted that throughout the specification and claims the terms blocked and unblocked refer to the presence or absence of a substantial central beam obstruction, as distinct from the presence or absence of a material used for beam filtering.
- The embodirnent of Fig. lB is preferably generally identical to that of Fig. lA but, unlike the prior art, includes a beam blocker 22, which is generally radiation impervious, disposed within collim~tin~ unit 20. Blocker 22 may have any a~ ly shape, such as conical. The at least partially hollow radiation pathway in the collimator defines a diverging hollow beam outside the collimator.
Fig. lC illustrates a collimator assembly including an exterior shield 30 defining a location 32 for a large source of radiation, indicated by reference numeral 34. The source 34 is typically a pack of radioactive material, such as cobalt-60. The exterior shield 30 is formed with a bore 36 extending outwardly from location 32. Preferably a collim~ting unit 40 is disposed in the bore 36.
In the embodiment of Fig. 1C, the collim Iting unit 40 is configured to form a non-hollow and converging radiation beam pathway. This pathway defines a non-hollow beam converging towards the focal point and diverging away from the focal point outside the collimator.
The embodiment of Fig. lD is identical to that of Fig. lC but also includes a beam blocker 42, which is generally radiation impervious, disposed within collim~ting unit 40. Blocker 42 may have any arbitrary shape such as conical. The at least partially hollow and converging radiation pathway in the collimator defines a beam outside the collimator which is converging and hollow near the collimator exit, non-hollow at the focus away from the collimator exit, and diverging and hollow at a distance from the focus.
It is appreciated that any of the collimators of Figs. lA - lD may be used to form an interchangeable collimator radiation generator. Any of the collimator elements may be simply removed from the shield and another collimator element inserted in its place. Alternatively, the collimator elements may be rigidly embedded in a movable shield, wherein a particular collimator element may be selected by suitably moving the shield.
Reference is now made to Figs. 2A, 2B and 2C which illustrate three di~e~ t cross beam profile configurations of radially symmetric beams in planes perpendicular to the corresponding beam axis.
Fig. 2A illustrates a cross beam profile of a non-hollow beam produced either by a prior art collimator according to Fig. lA, a collimator of the present invention according to Fig.
1C or a collimator of the present invention according to Fig. lD, at its focus. It is noted that the beam profile is characterized by a relatively high level of radiation near the center of the target, and the radiation level falls offrapidly at a certain distance from the center.
Fig. 2B illustrates a cross beam profile produced either by a collimator of the present invention according to Fig. lB, or a collimator of the present invention according to Fig.
lD at a distance from its focus. It is noted that the beam profile is characterized by a relatively negligible level of radiation near the center of the profile, and a relatively high level generally at the periphery of the profile.
Fig. 2C illustrates a combined cross beam profile of a non-hollow beam and a hollow beam. It is noted that the beam profile of Fig. 2C is disting~ hed from the profile of Fig.
2A, in that the beam profile of Fig. 2C has a generally sharper or steeper fall off than that of Fig.
2A, when the hollow beam is produced by a collimator according to Fig. lD. The steeper fall off may be useful in protecting neighboring tissue from unwanted radiation.
It is appreciated that various features of the invention which are, for clarity,described in the contexts of separate embodiments may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment may also be provided separately or in any suitable subcombination.
It will be appreciated by persons skilled in the art that the present invention is not ~ Iimited to what has been particularly shown and described hereinabove. Rather, the scope of the present invention is defined only by the claims that follow:
l D Oli Tl-IE INVl~Nl'ION
Tlle present invenfioll relates to radiosutgely genel-ally, and particulal-ly tocollimators used in stereotactic radios~n-~ery.
13ACKGROIJND Ol~ Tl IE INVENrrlON
Stereotactic ra~iosurgery invt)lves dose accu~ llatioll in a target volume by irradiating the target fi-om a multilllicity of orientations witll rlnely collimated beams.
rI lle use of stel-eotactic r~(liosur~ety to ren(ler tiss~le necrotic is well established an(l vario~ls systems are cul-l-elllly use(' s'or stereotactic ra(liosln~ely. The prior art recognizes the need to conline ra(lialion as mucll as possil)le to tl-e tat~et volullle being treated. Generation of a clesired dose l~attelll in an(l o~lt ortl-e tnl-L,et volulllc is Ille ol)jeclive of a treatnlent plall. Sucll a plan takes into accoutlt linlitatiolls of tl~e l~artic~llal- ra(lios~ ical system used. System lypes include a Gamllla Unit whicll utilizes a nlulfil~licity Or Cobalt-6() sources arl-al~ged on a spherical surface, a linear accelerator (I,INAC) wl~ich ufili~es a proton bealll source nlounte(l on a rotating gantry, and a stationary genel-alol- lor a cl-arge(J l)arlicles bealll. l'llese radioslll-gical systems, as well as associated metllods, cllalaclcl-istics an(l l~erforlllallce al-e described in various publicafiolls, e.g., Stereotactic Racliosul ~ery, Alexan(lel- E. el al.7 McGraw-l-lill, 19~)3, and Neul oslJI-L~ery Clin s o~Nortll America, vol. ~, no. 1, L utlsfol(l l, D. (e(litor), W.13. S~l~ln(lers Co., Jan. 1992.
Treatlllellt ~!anllill~ capabililies inclu(le selectin~ a dose level to the tar~set, choosing cnllinlatols for bealll s}la~in~ al1(1 a detern~inatioll of l-eam orientations fi-om whicll ra{iialion is deposited in tlle target vol~ln-e. ln or~ler to re(lLIce tl~e (lose deposite(l in llealtlly tissue outside the target vol~lme, it is generally desiral~le to spl-ea(l beam orientations over a wide range and to employ collinlators wllicl~ conl;lle tlle ra(liatioll to t}le targel vol~nlle.
Pl-ior art stere(-)tactic radio.ciulgel-y systems incolpol-ate point soul-ces for generatillg radiation l~ealns (a lloinl soln-ce is a ra(lialioll source wllicll is signilicantly smaller than the tar~et). A collimator associated witll a }~oin~ sourGe pl~od~lces a divelging beam, i.e., the beasn widtll increases witll inclease(l (lislance l'lonl the soulce. ~ucll a diverging collimator~ ortlle type used in conjullcti~ witll a l lNAC or ~itll a (Janlllla Unit, is nla(le of a radiatioll inlpervious material configured to define a divel-~,illg ra(liation patll.
22nlgg8 The collimators associated with prior art stereotactic radiosurgery systems -incorporate clear (non-blocked) radiation paths. The intensity of a radiation beam produced by such a clear path collimator, in any plane perpendicular to the beam axis, decreases monotonically with radial distance from the axis. One of the consequences of such a beam profile is that prior art stereotactic radiosurgery methods are restricted for treating targets smaller than about 50 millimeters in diameter. The apparent reason is the increased radiation to healthy tissue.
SUMMARY OF THE INVENTION
The present invention seeks to provide improved apparatus and techniques for radiosurgery which represent a radical departure from the prior art.
The present invention includes a hollow path collimator, diverging or converging, which is capable of producing a hollow radiation beam at the target, thus providing an ability to irradiate mainly the target boundary. Causing tissue to be necrotic by irradiation mainly at the target boundary may have adequate clinical results while reducing the radiation dosage to healthy tissue. The prior art does not describe a collimator for stereotactic radiosurgery incorporating a hollow radiation path.
The prior art does not describe a stereotactic radiosurgery system utili~in~ a converging collimator, i.e., one with a converging radiation path. In the present invention, a converging collimator may be used to produce a hollow radiation path.
The prior art does not describe a system ~Itili~ing an area source for generating radiation beams for stereotactic radiosurgery. An area source or a large source is a radiation source which is comparable in size or larger than the target. An area source, e.g., a Co-60 pack used for conventional radiotherapy, could be much cheaper for stereotactic radiosurgery than a LINAC or an array of 201 sources incorporated in the Gamma Unit.
In the present invention, a hollow radiation path collimator may be used to reduce the penumbra associated with a radiation beam produced by an area source. Since a single hollow radiation path reduces also the beam intensity (by blocking an internal portion of the beam), it may be advantageous to incorporate several hollow radiation paths in a single collimator.
However, increasing the number of radiation paths may also increase the penumbra, suggesting that a desirable compromise between increasing beam intensity and increasing penumbra be reached. Such a compromise, for a given source and a given collimator material, may be obtained ~y selecting optimally the number of hollow paths and the associated geometrical properties. The prior art does not describe the use of an area source and a collimator incorporating one or more hollow paths for stereotactic radiosurgery.
There is thus provided in accordance with a prerel~ed embodiment of the present invention, a collimator for use in radiosurgery including material which is generally radiation impervious and which is configured to define at least one at least partially hollow radiation path.
In accordance with a prerell ed embodiment of the present invention, the collimator further includes a shield which is generally radiation impervious, the shield having formed therein a beam passageway, and at least one beam blocker which is generally radiation impervious, the at least one beam blocker being located in the beam passageway so as to form the at least one at least partially hollow radiation path.
There is also provided in accordance with a p~ ed embodiment of the present invention, a collimator for use in radiosurgery including material which is generally radiation impervious and which is configured to define a converging radiation path.
There is also provided in accordance with a preferred embodiment of the present invention, an irr~ ting device for use in radiosurgery including at least one source of radiation arranged to irradiate a target, and at least one collimator disposed between the at least one source of radiation and the target and including material which is generally radiation impervious and which is configured to define at least one at least partially hollow radiation path.
In accordance with a preferred embodiment of the present invention, the at leastone collimator includes a shield which is generally radiation impervious, the shield having formed therein a beam passageway, and at least one beam blocker which is generally radiation impervious, the at least one beam blocker being located in the beam passageway so as to form the at least one at least partially hollow radiation path.
There is also provided in accordance with a preferred embodiment of the present invention, an irradiating device for use in radiosurgery including at least one source of radiation arranged to irradiate a target, and at least one collimator disposed between the at least one source of radiation and the target and including material which is generally radiation impervious and which is configured to define at least one converging radiation path.
2201g98 - There is also provided in accordance with a preferred embodiment of the present ~invention, a method for radiosurgery including the steps of providing an irradiating device including at least one source of radiation arranged to irradiate a target, and at least one collimator disposed between the at least one source of radiation and the target and including material which is generally radiation impervious and which is configured to define at least one at least partially hollow radiation path, producing radiation beams with the irra~iatin3~ device, and directing the radiation beams at a target volume from a multiplicity of orientations.
There is also provided in accordance with a pl~relled embodiment of the present invention, a method for radiosurgery including the steps of providing an irradiating device including at least one source of radiation arranged to irradiate a target, and at least one collimator disposed between the at least one source of radiation and the target and including material which is generally radiation impervious and which is configured to define at least one converging radiation path, producing radiation beams with the irradiatinQ; device, and directing the radiation beams at a target volume from a multiplicity of orientations.
There is also provided in accordance with a preferred embodiment of the present invention, a method for radiosurgery including the steps of providing at least one radiation source, collimating radiation from the at least one source to produce radiation beams which are at least partially hollow at the location of a target, and directing the at least partially hollow radiation beams at the target from a multiplicity of orientations to produce a radiation dose pattern having a substantially higher dose level at the boundary of the target and a substantially lower dose level at the interior of the target.
In accordance with a preferred embodiment of the present invention, the method further includes the steps of collim~ting radiation from the at least one source to produce non-hollow radiation beams at the location of the target, and directing the non-hollow radiation beams at the target from a multiplicity of orientations to produce an additional radiation dose pattern having a substantially higher dose level at the interior of the target and a substantially lower dose level at the boundary of the target.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be understood and appreciated more fully from the following detailed description, taken in conjunction with the drawings in which:
Fig. 1 A is an illustration of a prior art radiation collimator;
Figs. lB, lC and lD illustrate three radiation collimators, constructed and operative in accordance with three alternative preferred embodiments of the present invention;
and Figs. 2A, 2B and 2C are illustrations of three di~lellt cross beam profile configurations of radially symmetric beams in planes perpendicular to the corresponding beam axis;
wherein Fig. 2A illustrates a non-hollow cross beam profile produced either by aprior art collimator according to Fig. lA, a collimator of the present invention according to Fig.
lC or a collimator of the present invention according to Fig. lD, at its focus;
Fig. 2B illustrates a hollow cross beam profile produced either by a collimator of the present invention according to Fig. lB, or a collimator of the present invention according to Fig. lD at a distance from its focus; and Fig. 2C illustrates a superposition of a hollow beam profile and a non-hollow beam profile.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Reference is now made to Fig. lA, which illustrates a prior art radiation collimator, and to Figs. lB, lC and lD which illustrate three alternative embodiments of radiation collimators constructed and operative in accordance with a pre~ell~d embodiment of the present invention. The radiation collimators of Figs. lA - lD are characterized in that they are formed of material which is generally radiation impervious. The radiation collimator shown in Fig.
lA is configured to define a non-hollow and diverging radiation pathway. Radiation collimators shown in Figs. lB and lD are configured to define an at least partially hollow radiation path. The radiation collimator shown in Fig. lC is configured to define a non-hollow and converging radiation pathway.
The hollow radiation path is useful for precise radiation treatment of targets in accordance with a preferred embodiment of the present invention whereby it is desired to irradiate the periphery of the target without substantially irr~ ting the center thereof~ or whereby it is desired to irradiate a target using a large source of radiation. It is noted that throughout the specification and claims, the terms large source of radiation and small source of radiation refer to 22~
~he relative size of the radiation source compared to the size of the irradiated target. A large ~ source of radiation is comparable in size or larger than the target, while a small source of radiation is significantly smaller than the target.
Fig. lA illustrates a collimator assembly including an exterior shield 10 defining a location 12 for a source of radiation, indicated by reference numeral 14. The exterior shield 10 is formed with a bore 16 extending outwardly from location 12. Preferably a collim~ting unit 20 is disposed in the bore 16.
In the embodiment of Fig. 1A, the collim~ting unit 20 defines an unblocked diverging radiation beam pathway. It is noted that throughout the specification and claims the terms blocked and unblocked refer to the presence or absence of a substantial central beam obstruction, as distinct from the presence or absence of a material used for beam filtering.
- The embodirnent of Fig. lB is preferably generally identical to that of Fig. lA but, unlike the prior art, includes a beam blocker 22, which is generally radiation impervious, disposed within collim~tin~ unit 20. Blocker 22 may have any a~ ly shape, such as conical. The at least partially hollow radiation pathway in the collimator defines a diverging hollow beam outside the collimator.
Fig. lC illustrates a collimator assembly including an exterior shield 30 defining a location 32 for a large source of radiation, indicated by reference numeral 34. The source 34 is typically a pack of radioactive material, such as cobalt-60. The exterior shield 30 is formed with a bore 36 extending outwardly from location 32. Preferably a collim~ting unit 40 is disposed in the bore 36.
In the embodiment of Fig. 1C, the collim Iting unit 40 is configured to form a non-hollow and converging radiation beam pathway. This pathway defines a non-hollow beam converging towards the focal point and diverging away from the focal point outside the collimator.
The embodiment of Fig. lD is identical to that of Fig. lC but also includes a beam blocker 42, which is generally radiation impervious, disposed within collim~ting unit 40. Blocker 42 may have any arbitrary shape such as conical. The at least partially hollow and converging radiation pathway in the collimator defines a beam outside the collimator which is converging and hollow near the collimator exit, non-hollow at the focus away from the collimator exit, and diverging and hollow at a distance from the focus.
It is appreciated that any of the collimators of Figs. lA - lD may be used to form an interchangeable collimator radiation generator. Any of the collimator elements may be simply removed from the shield and another collimator element inserted in its place. Alternatively, the collimator elements may be rigidly embedded in a movable shield, wherein a particular collimator element may be selected by suitably moving the shield.
Reference is now made to Figs. 2A, 2B and 2C which illustrate three di~e~ t cross beam profile configurations of radially symmetric beams in planes perpendicular to the corresponding beam axis.
Fig. 2A illustrates a cross beam profile of a non-hollow beam produced either by a prior art collimator according to Fig. lA, a collimator of the present invention according to Fig.
1C or a collimator of the present invention according to Fig. lD, at its focus. It is noted that the beam profile is characterized by a relatively high level of radiation near the center of the target, and the radiation level falls offrapidly at a certain distance from the center.
Fig. 2B illustrates a cross beam profile produced either by a collimator of the present invention according to Fig. lB, or a collimator of the present invention according to Fig.
lD at a distance from its focus. It is noted that the beam profile is characterized by a relatively negligible level of radiation near the center of the profile, and a relatively high level generally at the periphery of the profile.
Fig. 2C illustrates a combined cross beam profile of a non-hollow beam and a hollow beam. It is noted that the beam profile of Fig. 2C is disting~ hed from the profile of Fig.
2A, in that the beam profile of Fig. 2C has a generally sharper or steeper fall off than that of Fig.
2A, when the hollow beam is produced by a collimator according to Fig. lD. The steeper fall off may be useful in protecting neighboring tissue from unwanted radiation.
It is appreciated that various features of the invention which are, for clarity,described in the contexts of separate embodiments may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment may also be provided separately or in any suitable subcombination.
It will be appreciated by persons skilled in the art that the present invention is not ~ Iimited to what has been particularly shown and described hereinabove. Rather, the scope of the present invention is defined only by the claims that follow:
Claims (11)
1. A collimator for use in radiosurgery comprising material which is generally radiation impervious and which is configured to define at least one at least partially hollow radiation path.
2. A collimator according to claim 1 and comprising:
a shield which is generally radiation impervious, said shield having formed therein a beam passageway; and at least one beam blocker which is generally radiation impervious, said at least one beam blocker being located in said beam passageway so as to form said at least one at least partially hollow radiation path.
a shield which is generally radiation impervious, said shield having formed therein a beam passageway; and at least one beam blocker which is generally radiation impervious, said at least one beam blocker being located in said beam passageway so as to form said at least one at least partially hollow radiation path.
3. A collimator for use in radiosurgery comprising material which is generally radiation impervious and which is configured to define a converging radiation path.
4. An irradiating device for use in radiosurgery comprising:
at least one source of radiation arranged to irradiate a target; and at least one collimator disposed between said at least one source of radiation and said target and comprising material which is generally radiation impervious and which is configured to define at least one at least partially hollow radiation path.
at least one source of radiation arranged to irradiate a target; and at least one collimator disposed between said at least one source of radiation and said target and comprising material which is generally radiation impervious and which is configured to define at least one at least partially hollow radiation path.
5. An irradiating device according to claim 4 and wherein said at least one collimator comprises:
a shield which is generally radiation impervious, said shield having formed therein a beam passageway; and at least one beam blocker which is generally radiation impervious, said at least one beam blocker being located in said beam passageway so as to form said at least one at least partially hollow radiation path.
a shield which is generally radiation impervious, said shield having formed therein a beam passageway; and at least one beam blocker which is generally radiation impervious, said at least one beam blocker being located in said beam passageway so as to form said at least one at least partially hollow radiation path.
6. An irradiating device for use in radiosurgery comprising:
at least one source of radiation arranged to irradiate a target; and at least one collimator disposed between said at least one source of radiation and said target and comprising material which is generally radiation impervious and which is configured to define at least one converging radiation path.
at least one source of radiation arranged to irradiate a target; and at least one collimator disposed between said at least one source of radiation and said target and comprising material which is generally radiation impervious and which is configured to define at least one converging radiation path.
7. A method for radiosurgery comprising the steps of:
providing an irradiating device comprising at least one source of radiation arranged to irradiate a target, and at least one collimator disposed between said at least one source of radiation and said target and comprising material which is generally radiation impervious and which is configured to define at least one at least partially hollow radiation path;
producing radiation beams with said irradiating device; and directing said radiation beams at a target volume from a multiplicity of orientations.
providing an irradiating device comprising at least one source of radiation arranged to irradiate a target, and at least one collimator disposed between said at least one source of radiation and said target and comprising material which is generally radiation impervious and which is configured to define at least one at least partially hollow radiation path;
producing radiation beams with said irradiating device; and directing said radiation beams at a target volume from a multiplicity of orientations.
8. A method for radiosurgery comprising the steps of:
providing an irradiating device comprising at least one source of radiation arranged to irradiate a target, and at least one collimator disposed between said at least one source of radiation and said target and comprising material which is generally radiation impervious and which is configured to define at least one converging radiation path;
producing radiation beams with said irradiating device; and directing said radiation beams at a target volume from a multiplicity of orientations.
providing an irradiating device comprising at least one source of radiation arranged to irradiate a target, and at least one collimator disposed between said at least one source of radiation and said target and comprising material which is generally radiation impervious and which is configured to define at least one converging radiation path;
producing radiation beams with said irradiating device; and directing said radiation beams at a target volume from a multiplicity of orientations.
9. A method for radiosurgery comprising the steps of:
providing at least one radiation source;
collimating radiation from said at least one source to produce radiation beams which are at least partially hollow at the location of a target; and directing said at least partially hollow radiation beams at said target from a multiplicity of orientations to produce a radiation dose pattern having a substantially higher dose level at the boundary of said target and a substantially lower dose level at the interior of said target.
providing at least one radiation source;
collimating radiation from said at least one source to produce radiation beams which are at least partially hollow at the location of a target; and directing said at least partially hollow radiation beams at said target from a multiplicity of orientations to produce a radiation dose pattern having a substantially higher dose level at the boundary of said target and a substantially lower dose level at the interior of said target.
10. A method according to claim 9 and further comprising the steps of:
collimating radiation from said at least one source to produce non-hollow radiation beams at the location of said target; and directing said non-hollow radiation beams at said target from a multiplicity of orientations to produce an additional radiation dose pattern having a substantially higher dose level at the interior of said target and a substantially lower dose level at the boundary of said target.
collimating radiation from said at least one source to produce non-hollow radiation beams at the location of said target; and directing said non-hollow radiation beams at said target from a multiplicity of orientations to produce an additional radiation dose pattern having a substantially higher dose level at the interior of said target and a substantially lower dose level at the boundary of said target.
11
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| IL118496 | 1996-05-30 | ||
| IL11849696A IL118496A0 (en) | 1996-05-30 | 1996-05-30 | Collimators |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2201998A1 true CA2201998A1 (en) | 1997-11-30 |
Family
ID=11068917
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002201998A Abandoned CA2201998A1 (en) | 1996-05-30 | 1997-04-07 | Collimators |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0811991A1 (en) |
| JP (1) | JPH1052510A (en) |
| CA (1) | CA2201998A1 (en) |
| IL (1) | IL118496A0 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102005011467B4 (en) * | 2005-03-12 | 2008-02-28 | Smiths Heimann Gmbh | Adjustable focal length collimator, directed method and X-ray inspection system |
| CN102446571B (en) * | 2010-09-30 | 2014-03-05 | 上海世鹏实验室科技发展有限公司 | Self-focusing radioactive source device and radiation device thereof |
| CN107497060B (en) * | 2014-12-08 | 2020-02-28 | 南京中硼联康医疗科技有限公司 | Beam shaping body for neutron capture therapy |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2331867A1 (en) * | 1975-11-14 | 1977-06-10 | Commissariat Energie Atomique | Collimator for neutron beam from a nuclear reactor - esp. water moderated, ensuring easier handling and minimum irradiation |
| DE3534686C1 (en) * | 1985-09-28 | 1987-05-07 | Bbc Reaktor Gmbh | Device for irradiating an object with a portable, thermal neutron generating source |
| DE3934321A1 (en) * | 1989-10-13 | 1991-04-18 | Siemens Ag | X=ray tube with window - of varying cross=section to reduce extra-focal radiation |
| US4991189A (en) * | 1990-04-16 | 1991-02-05 | General Electric Company | Collimation apparatus for x-ray beam correction |
| DE4130039A1 (en) * | 1991-09-10 | 1993-03-11 | Philips Patentverwaltung | X=ray beam expander used in computer tomograph - has beam shaping aperture formed by confinement bodies |
| US5332908A (en) * | 1992-03-31 | 1994-07-26 | Siemens Medical Laboratories, Inc. | Method for dynamic beam profile generation |
-
1996
- 1996-05-30 IL IL11849696A patent/IL118496A0/en unknown
-
1997
- 1997-04-01 EP EP97302218A patent/EP0811991A1/en not_active Withdrawn
- 1997-04-07 CA CA002201998A patent/CA2201998A1/en not_active Abandoned
- 1997-05-21 JP JP9130607A patent/JPH1052510A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| EP0811991A1 (en) | 1997-12-10 |
| IL118496A0 (en) | 1996-09-12 |
| JPH1052510A (en) | 1998-02-24 |
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