Multileaf collimator and compensator for radiotherapy machines
First Claim
1. An apparatus forming an accessory and improvement to medical electron accelerators generating an x-ray fan beam, comprising:
- control means for providing dynamic control of radiation dose using a collimator in a treatment volume of arbitrary external and internal shape including dynamic control of radiation varying in intensity both in space and time independently within said arbitrary external shape while treatment of a subject progresses.
3 Assignments
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Accused Products
Abstract
In a radiation therapy machine it is desirable to produce irregular radiation field shapes in order to shield critical organs not invaded by the tumor. A system is provided using a multileaf collimator formed of a multiplicity of heavy metal bar leaves driven relative to a pair of frames which are driven relative to jaws of a rectangular field collimator. A multiplicity of compensators, one attached to each leaf on one of the pair of frames is used to adjust the local intensity of the radiation within the field. The x-ray beam is limited to a fan with the jaws, the ends and selected parts of the fan are blocked by the multileaf collimator, and the intensity within various portions of the remaining beam is adjusted with compensators. The field of the fan beam is dynamically controlled by these means while the patient table is moved perpendicular to the plane of the fan beam.
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Citations
26 Claims
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1. An apparatus forming an accessory and improvement to medical electron accelerators generating an x-ray fan beam, comprising:
control means for providing dynamic control of radiation dose using a collimator in a treatment volume of arbitrary external and internal shape including dynamic control of radiation varying in intensity both in space and time independently within said arbitrary external shape while treatment of a subject progresses. - View Dependent Claims (2, 3)
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4. An accessory apparatus for a source of x-rays for radiation of a subject, the source of rays including x-ray blocking jaws mounted on a jaw-frame for defining a rectangular field x-ray field;
- the apparatus comprising;
defining means for dynamically limiting the radiation to radiation pixels while radiation of the subject progresses; and compensating means for dynamically reducing the intensity of x-rays by 1 to 95% within radiation pixels not blocked by said defining means before the x-rays reach the subject while radiation progresses; said defining and compensating means being mounted on the jaw frames and acting in concert with the jaws. - View Dependent Claims (5, 6)
- the apparatus comprising;
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7. An apparatus acting as a collimator in a radiation therapy machine having jaws mounted in a jaw frame for limiting a fan beam x-ray radiation field to rectangular boundaries, comprising:
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leaf means for further blocking and shaping a radiation field within the rectangular boundaries, said leaf means including a multiplicity of straight leaves opaque to x-rays; mounting means for mounting said leaf means on the jaw frame, said mounting means including leaf support frame assemblies; drive means for providing motion of said leaf means relative to said leaf support frame assemblies and for motion of said leaf support frame assemblies relative to the jaw frame; and compensator means for adjusting the intensity of the x-rays at the subject within the radiation field defined by the jaws and leaf means, said compensator means being independently insertable into the radiation field. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A method of operating a radiation therapy machine comprising the steps of:
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(a) limiting the radiation field to a fan beam using two orthogonal pairs of jaws of radiation opaque material; (b) dynamically further limiting the radiation field using a multiplicity of straight leaves of radiation opaque material, said leaves being mounted in a first of a pair of leaf support frame assemblies which are independently movable relative to the jaws; (c) dynamically limiting the radiation intensity within the radiation field by means of compensators mounted to leaves in a second of a pair of leaf support frames, said step being performed simultaneously to step (b); (d) moving a table holding a patient along an axis perpendicular to the fan beam in accordance with a patient treatment plan, said step being performed simultaneous with steps (b) and (c).
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20. An irradiation treatment method comprising:
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(a) causing an irradiation source to emit a two-dimensional radiation fan beam in a first plane; (b) controlling the location of matter to be treated by irradiation by said fan beam so that said matter is movable along a line which is perpendicular to the plane of said fan beams; (c) interposing an adjustable means for shaping the beam and controlling the beam intensity between said matter to be irradiated and said irradiation source; (d) calculating a desired shape and intensity distribution for the portion of said fan beam which impinges on said matter for each position of said matter along said line so that the fan beam radiation which falls on said matter selectively irradiates a preselected volume of said matter with a preselected intensity distribution; (e) causing said adjustable means for shaping the beam and controlling the beam intensity to be adjusted responsive to said calculated desired beam shape to form a shaped and modulated beam; and (f) irradiating said matter in said plane with said shaped and modulated beam by causing said source to emit radiation. - View Dependent Claims (21, 22, 23)
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24. An apparatus for radiation of a subject, comprising:
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an electron accelerator source of x-ray beams, said accelerator being mounted in a gantry for changing the direction of incidence of x-ray beams on a subject, a subject holding table, said subject holding table including means for moving the subject along a line relative to the x-ray beam, defining means for dynamically limiting the radiation to radiation pixels while radiation of the subject progresses; compensating means for dynamically reducing the intensity of x-rays by 1 to 95% within radiation pixels not blocked by said defining means before the x-rays reach the subject while radiation progresses, and computer means for controlling said accelerator, said table, said defining means and said compensating means in accord with a programmed plan. - View Dependent Claims (25, 26)
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Specification