Verification system for radiation therapy
AssigneeWisconsin Alumni Research Foundation
InventorsStuart Swerdloff, Thomas R. Mackie, Timothy Holmes
Life of this patent
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Abstract
A radiation therapy apparatus includes a compensator with moving leaves to attenuate a radiation beam and a compensator verification system to determine if the attenuating leaves are moving in accordance with desired position signals. Two radiation intensity monitoring chambers, one chamber on either side of a patient within a radiation beam, produce beam fluence data used by a computer to construct radiation absorption images and to evaluate the functionality of the compensator. The absorption image can be used for both radiation dose verification and planning of suitable subsequent therapy sessions.
Claims15
In a radiation therapy machine having a radiation source for producing a radiation beam directed toward a patient at a gantry angle, the beam including a plurality of adjacent rays, a controller comprising:
- an attenuation means disposed between the radiation source and the patient for independently controlling the fluence of each ray of the beam;
- a compensator control for controlling the attenuation means according to first desired ray fluences at a first gantry angle;
- a pre-patient monitor disposed between the attenuating means and the patient having a plurality of monitor segments, adjacent monitor segments subtended by adjacent rays of the beam, each segment producing a fluence signal proportional to the measured fluence of the ray subtending the segment;
- comparison means for comparing the desired fluence of a ray to the measured fluence to produce a difference value;
- and
- limit means for producing an error signal if the difference value is outside of a predetermined error range.
In a radiation therapy machine having a radiation source for producing a radiation beam directed toward a patient at a gantry angle, the beam including a plurality of adjacent rays, a controller comprising:
- a plurality of radiation attenuating leaves;
- a supporting structure positioned generally between the radiation source and the patient for guiding the leaves between a closed state within the radiation beam, each leaf thus occluding one ray of the beam, and an open state outside of the radiation beam to allow unobstructed passage of the ray;
- motivation means for independently exerting a force on each leaf to move each leaf between the open and closed state;
- compensator control communicating with the motivation means for controlling the desired ratio of the period of time during which each leaf is in the closed state to the period during which each leaf is in the open state to control the average fluence of each ray of the beam;
- a position sensor for determining when each leaf is in the open state and when each leaf is in the closed state, and producing an actual ratio of the period of time the leaf is in the open state to the period of time each leaf is in the closed state;
- and
- an error detector for generating an error signal by comparing an actual ratio to the desired ratio.
In a radiation therapy machine having a radiation source for producing a radiation beam directed toward a patient at a gantry angle, the beam including a plurality of adjacent rays, the machine having an attenuating means disposed between the radiation source and the patient for independently controlling the fluence of each ray of the beam, a verification system comprising:
- a pre-patient monitor generally disposed between the attenuating means and the patient for determining separately a pre-patient fluence of each ray of the beam prior to entering the patient;
- and
- a post-patient monitor generally disposed opposite the pre-patient monitor with respect to the patient and within the fan beam for determining a post-patient fluence of each ray of the beam exiting the patient.
Dependencies are inferred from the claim text.