WO2001027939A1 - Compensateur de modulation d'intensite comportant des plaques et des couches multiples pour des appareils de therapie par rayonnement - Google Patents

Compensateur de modulation d'intensite comportant des plaques et des couches multiples pour des appareils de therapie par rayonnement Download PDF

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Publication number
WO2001027939A1
WO2001027939A1 PCT/US2000/028023 US0028023W WO0127939A1 WO 2001027939 A1 WO2001027939 A1 WO 2001027939A1 US 0028023 W US0028023 W US 0028023W WO 0127939 A1 WO0127939 A1 WO 0127939A1
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Prior art keywords
leaves
compensator
radiation
layers
layer
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PCT/US2000/028023
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English (en)
Inventor
Robert E. Wallace
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The Regents Of The University Of California
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Priority to AU11955/01A priority Critical patent/AU1195501A/en
Publication of WO2001027939A1 publication Critical patent/WO2001027939A1/fr

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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
    • G21K1/04—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating using diaphragms, collimators using variable diaphragms, shutters, choppers
    • G21K1/046—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating using diaphragms, collimators using variable diaphragms, shutters, choppers varying the contour of the field, e.g. multileaf collimators
    • 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
    • G21K1/04—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating using diaphragms, collimators using variable diaphragms, shutters, choppers
    • 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
    • A61N2005/1095—Elements inserted into the radiation path within the system, e.g. filters or wedges

Definitions

  • the field of this invention is compensators for radiation therapy.
  • Tissue compensation is a well-known and well-described principal and method in practiced radiation therapy of tumors .
  • Medical Physics 23(7):1 i99-1205 (1996); Ma, et. al, Physics in Medicine and Biology 43(6):1629- 43 (1998); Xia, et. al., Medical Physics 25(8): 1424-34 (1998); Ellis, F., Brit. J. Radiology 33:404, 1960; Hall, E.J. and Oliver, R., Brit. J.
  • Conformal radiation therapy is the established application of multiple, intersecting shaped radiation beams comprised of fields shaped, in two dimensions, to geometrically conform to the shape of a target from the viewpoint of the origin of the radiation beam.
  • a conformal radiation field is a geometrical construct. The confluence of a number of such fields can lead to a radiation dose distribution that conforms to the convex hull surface enclosing a targeted tumor volume.
  • An intensity modulated, compensated beam is a field with cross-field, position dependent, intensity.
  • a multi-layer, multi-leaf compensator, MLMLC is a device capable of both forms of field shaping, by geometry and by intensity.
  • intensity maps in such a field can be constructed to avoid sensitive non-target structures.
  • the confluence of a number of such fields can lead to a radiation dose distribution that conforms to the concave surface enclosing the volume of a targeted tumor, while minimizing dose to sensitive normal structures that are interposed in the applied radiation field(s) and while maximizing the target dose homogeneity. This is a significant goal in clinical radiotherapy where radiologically involved normal tissue(s) and organs must be spared debilitating radiation dose while delivering tumoricidal radiation dose to a defined target.
  • a multi-leaf device is a radiation beam collimation device that provides shaped fields through the agency of independently positioned divergent or plane parallel plates that provide full or partial attenuation of a photon source spectrum and that enter a rectangular radiation beam from sides perpendicular to the direction of a beam central ray-line customarily directed toward a target. Such leave- plates are positioned under programmatic control or by manual techniques.
  • the MLMLC provides intensity modulation of a radiation beam within a defined "open" field shape by placement of one or more partially attenuating leaves into the open area of a photon beam.
  • full attenuation for shaping is accomplished by the interposition of all layers of the MLMLC between the radiation source and a test point in space.
  • the MLC In the MLC, this is accomplished with the interposition of full attenuation leaves.
  • field intensity modulation is accomplished employing one or both of two principal methods: by temporal modulation via independently moving leaves, and by temporal modulation via superposition of appropriately shaped sub-field segments that may block parts of the "open" field for a fraction of the time required to deliver the highest intensity portion of the field.
  • the time to accomplish the number of steps for static placement of MLC leaves or the time required for the dynamic motion of the MLC leaves is generally greater than the time to deliver a proscribed radiation dose in the highest intensity portion of the open field.
  • a manually configured MLMLC device can, in principle, provide delivery of all modulated doses in time on the order of the amount of time required to deliver prescribed radiation dose in the open field, at substantially less costly than a servo controlled MLC device in achieving the same therapeutic goal.
  • Yao U. S. Patent No.5591983, European Patent No. 751532A1
  • Yao devices leafs are positioned to shape a radiation field. This is an improvement over a two-layer multileaf collimator described by Nunan (U. S. Patent No.4868844) where the leaves of each layer occupied the same vertical space, one over the other, aligned on the interleaf gaps, and providing no relief of radiation leakage through the gaps.
  • Nunan U. S. Patent No.4868844
  • a pair of leaves are moved together to block a portion of the radiation beam and relative to each other so that the upper leaf extends further than the lower leaf.
  • No.5724403 describe a system using an MLC leaf bank opposed by a monolithic collimator, which is used in conjunction with a wedge filter, to provide one- dimensional intensity modulation across a radiation field .
  • Swerdlof, et. al. (U. S. Patent No.5351280) describes a two layer multi-leaf collimator similar in conception to that of Yao, yet capable of adjusting beam intensity in a tomographic teletherapy unit by temporal modulation.
  • full attenuation leafs in each of the two layers are construed to move independently of all other leafs.
  • Leafs in a given layer are separated by gaps nearly the dimension of the leaf in the layer above or below. This reduces friction while mitigating inter-leaf radiation leakage.
  • a variable radiation fluence intensity can be obtained via temporal modulation. Swerdlof, et.
  • the MLMLC device is comprised of several layers of partially attenuating leafs that, when arranged in the path of a segment of a radiation beam, provide a desired intensity.
  • the MLMLC device can be realized to provide a greater latitude of beam intensity than the former in similar elapsed time.
  • the MLMLC device is comprised of multiple layers of partially attenuating leafs, each leaf bank offset by at most one half the width of the leaf width, similar to the invention of Yao .
  • the device can be realized using selected leaf widths providing variable spatial resolution, similar to that described by Vilsmeier .
  • variable attenuation at positions within the radiation field is accomplished by the static or dynamic arrangement of selected leafs in a stack in the path of the radiation beam.
  • Maughan, et. al. (U. S. Patent No.4754147) described a device that is in principle capable of variable attenuation, yet was conceived solely as a field shaping device using opposed arrays of nested-rod collimating elements .
  • Nunan, et. al. (U. S. Patent No.4868843) described an MLC invention that provides field shaping through the agency of multiple leaf collimation, with the addition of wedge shaped compensator finger-leafs articulated along the length of individual leafs of the MLC.
  • Devices that embody the Nunan et. al. feature provide two dimensional intensity modulation and beam compensation in a design that is similar in conception to the later device of Siochi, et. al.
  • the MLMLC device of the present invention differs significantly in form and in function from that described by Nunan, et. al.
  • the compensator finger leafs extended from the end of the field shaping collimator leafs, restrict position and effective intensity modulation when the field shape dictates that opposing collimator leaf ends reside in close proximity.
  • MLMLC device provides for a full range of intensity modulation at all field positions and may be realized as a mechanical adjunct to the field shaping system.
  • the present invention comprises a multiple layer multileaf compensator for selectively attenuating radiation intensity in predetermined regions of a radiation beam as used in the practice of medical radiation therapy.
  • the compensator includes first, second, and further layers of a plurality of elongated radiation blocking leaves, providing a different degree of beam attenuation in each layer or in combination of layers.
  • the leaves of each layer are arranged adjacent to one another so as to form two opposed rows of adjacently positioned leaves and are movable in a longitudinal direction (Y) which is generally transverse to the direction of the radiation beam so as to define radiation beam intensity shaping in the field passing through different combinations of partially attenuating leafs in overlying layers.
  • the layers are arranged one above the other in the beam direction and offset in the lateral direction (X) which is generally transverse to the beam direction and orthgonal to the longitudinal direction (Y) so that spaces between adjacent leaves of any layer are positioned over and under, respectively, leaves of adjacent layers.
  • the first advantage of placing the interleaf gaps of one layer below those of another layer and not necessarily in line of sight to the radiation source with the interleaf gaps of any other layer is that a looser fit between adjacent leaves of any one layer can be tolerated.
  • the second advantage of such an arrangement of layers, leaves, and gaps is that interleaf radiation leakage is minimized for the multiple layer multileaf compensator. This has the salutary effect of reducing interleaf friction, thereby reducing the strength and accuracy requirements on actuators to independently position individual leaves and thereafter maintain the positions. The ability to accurately place leaves of any layer to conform to any irregular shape is thereby improved.
  • FIG. 1 illustrates a perspective view, relative to a radiation source and relative to an it radiated volume, of a multiple layer, multileaf compensator device constructed in accordance with the present invention
  • FIG. 2 illustrates a multiple layer, multileaf compensator device constructed in accordance with the present invention, as seen from the leaf ends;
  • FIG. 3 illustrates an elevation view of the device shown in FIG. 2;
  • FIG. 4 illustrates a view of representative layers comprising the device shown in FIG. 2, as seen from the perspective of the radiation source.
  • FIG. 1 shows an abstracted view of a radiation therapy unit of conventional design, having a collimated source of radiation 1 from which emitted rays 2 diverge in the direction of the irradiated volume 3, typically a patient undergoing a therapeutic procedure.
  • the rays from the source pass through the multiple layer, multileaf compensator constructed in accordance with the present invention and which is attached to the realization of the abstracted radiation producing machine.
  • rays pass unabated through the open areas 16, 26, 36, up to N6 formed by the leaves 10,11, 20,21, 30,31, ... N0, N1 in banks 14,15, 24,25,
  • a ray may pass through a leaf in a bank of leaves in each layer of the device and thereby be reduced in intensity due to absorption in the intervening material of the occluding leaves.
  • a source of high energy photon radiation having representative uniform intensity 100 within the collimated aperture may be altered in the region of the irradiated volume 3 to have a representative compensated intensity distribution 101 through the agency of the present invention.
  • FIGURES 2, 2a, and 2b show perspective views of the device as seen from the ends of the leaves.
  • Rays 2 emanating from the radiation source 1 and passing through the multiple layer multileaf compensator having all leaves retracted form a field on some maximal dimension 5 at a plane within the irradiated volume 3.
  • a nominal maximum field dimension of 26cm by 40cm, at the field definition distance, would be applicable to a large majority of radiation therapeutic applications.
  • the maximal field can be accomplished using 26 leaves. Layers of leaves are supported by plates and standards 4.
  • the device is comprised of N layers of leaves of either non-uniform thickness, as shown in FIG 2 and 2a, or of uniform thickness, FIG 2b, each arrangement providing variable attenuation in different quantized steps yet by the same principle of the present invention.
  • leaves 10,11, 20,21, 30,31, ... N0,N1 in two banks 14,15, 24,25, 34,35, ... N4,N5, move in opposition across the field transverse dimension.
  • leaves may have uniform width, w n , - w n , or variable width in accord with the principle of Vilsmeier, et. al. (U. S. Patent No.5889834).
  • Leaves of adjacent layers may have gaps arranged to minimize leakage 8 using variable widths, or by using uniform widths 9.
  • Leaves are constructed of a suitable material, for example tungsten, that is both effective in attenuating high energy photon, but also that can be manufactured in a standardized manner.
  • FIG. 3 shows an elevation view from the side of the multiple layer multileaf compensator where it is apparent that individual leaves 10,11, 20,21, 30,31, ...
  • N0,N1 of uniform or non-uniform thickness, can be placed independent of leaves in any of the layers in the device. Positioning of leaves using mechanical cut-out bucks has been described by Maughan, et. al. (U. S. Patent No.4754147) and by Pastyr, et. al. (U. S. Patent No.4794629) or using automated means similar in conception to that of Leavitt, et. al. (U. S. Patent No.5160847).
  • the figure also shows an arrangement of leaves that provides differential compensation along individual rays 2 emanating from the radiation source through both leaves and open areas 16, ... N6.
  • FIG. 4 shows the shapes of irregular open areas 16, ... N6 in each layer of the device, as seen from the source of radiation, and the shaped mechanical bucks 17,18, ... N7,N8 for setting the device manually.
  • the leaves are shown as being set by manual means, actuators of a previously described type may be used to position and hold in place, the individual leaves of each layer.
  • the operation of leaves in any layer is as is conventional in prior art single layer multileaf collimator arrangements.
  • leaf thickness in each layer may be selected to provide at most fractional attenuation significantly different from that required for field shaping.
  • the nested rod collimator of Maughan, et. al. U. S. Patent No.4754147
  • various design changes can be made to leaf shape and dimension. All such changes, modifications, variations, and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by this patent, which is limited only by the claims that follow.

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  • Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Radiation-Therapy Devices (AREA)

Abstract

Compensateur de modulation d'intensité de rayonnement polyvalent, réutilisable comportant des plaques multiples et composé de couches multiples (14, 24, 34, ...N4) permettant de contrôler de façon manuelle et/ou systématique l'intensité du rayonnement en fonction d'une position de la section transversale d'un faisceau de radiothérapie (2), ce qui permet d'effectuer à la fois une modulation d'intensité (101) de forme de champ et de champ croisé pour des sources de photon (rayon X et rayon η).
PCT/US2000/028023 1999-10-08 2000-10-09 Compensateur de modulation d'intensite comportant des plaques et des couches multiples pour des appareils de therapie par rayonnement WO2001027939A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU11955/01A AU1195501A (en) 1999-10-08 2000-10-09 Multiple-layer, multiple-leaf, intensity modulating, compensator for radiation therapy machines

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US15863899P 1999-10-08 1999-10-08
US60/158,638 1999-10-08

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WO2001027939A1 true WO2001027939A1 (fr) 2001-04-19

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2017070433A1 (fr) * 2015-10-23 2017-04-27 The Regents Of The University Of California Plate-forme de radiothérapie par modulation d'intensité
US11000706B2 (en) 2016-12-13 2021-05-11 Viewray Technologies, Inc. Radiation therapy systems and methods

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4987309A (en) * 1988-11-29 1991-01-22 Varian Associates, Inc. Radiation therapy unit
US5591983A (en) * 1995-06-30 1997-01-07 Siemens Medical Systems, Inc. Multiple layer multileaf collimator
US5889834A (en) * 1995-09-28 1999-03-30 Brainlab Med. Computersysteme Gmbh Blade collimator for radiation therapy

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4987309A (en) * 1988-11-29 1991-01-22 Varian Associates, Inc. Radiation therapy unit
US5591983A (en) * 1995-06-30 1997-01-07 Siemens Medical Systems, Inc. Multiple layer multileaf collimator
US5889834A (en) * 1995-09-28 1999-03-30 Brainlab Med. Computersysteme Gmbh Blade collimator for radiation therapy

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2017070433A1 (fr) * 2015-10-23 2017-04-27 The Regents Of The University Of California Plate-forme de radiothérapie par modulation d'intensité
US10987523B2 (en) 2015-10-23 2021-04-27 The Regents Of The University Of California Platform for intensity modulated radiation therapy
US11000706B2 (en) 2016-12-13 2021-05-11 Viewray Technologies, Inc. Radiation therapy systems and methods
US11931602B2 (en) 2016-12-13 2024-03-19 Viewray Technologies, Inc. Radiation therapy systems and methods

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