US 6,438,202 B1 · Method using post-patient radiation monitor to verify entrance radiation and dose in a radiation therapy machine

Abstract

In radiotherapy, a high quality imaging array may be placed after the patient and opposite the radiation source to be used during radiation treatment to verify operation of a shutter system or similar device and/or to compute dose delivered to the patient. A model of the patient may be used and inverted in order to estimate values of energy fluence prior to absorption by the patient and overlapping of the various radiation beams passing through the patient. A test pattern of shutter excitation to illuminate a single ray at a time provides a simple method of obtaining the necessary model. The dose from this test pattern may be subtracted from the subsequent radiation treatment so as to provide limited or no increase in total dose to the patient.

Claims25

Dependent claims

A method of verifying patient dose in the operation of a radiotherapy machine having a radiation source operable to produce multiple rays of radiation having controllable fluence and directed across a patient volume to be received by a detector having multiple detector elements providing detectors signals at spatially separated points, each detector element receiving radiation from multiple rays, the method comprising the steps of:

(a) receiving a treatment plan to operate the radiation source to produce a set of rays of predetermined fluence;
(b) operating the radiotherapy machine according to the received treatment plan;
(c) concurrently with step (b) measuring the detector signals;
(d) processing the detector signals using a model of the expected attenuation and path of each ray passing from the radiation source through the patient volume to the detector to deduce a fluence of each of the set of rays;
and
(e) using the deduced fluence and information about the structure of a patient in the patient volume to determined a dose distribution to the patient.

3 more elements

A method of verifying operation of a radiotherapy shutter system in a radiotherapy machine having a radiation source positioned behind the shutter system, the shutter system operable to produce multiple rays of radiation having controllable fluence and directed across a patient volume to be received by a detector having multiple detector elements providing detectors signals at spatially separated points, each detector element receiving radiation from multiple rays, the method comprising the steps of:

(a) receiving a treatment plan to operate the shutter system to produce a set of rays of predetermined fluence;
(b) operating the radiotherapy machine according to the received treatment plan;
(c) concurrently with step (b) measuring the detector signals;
(d) processing the detector signals using a model of the expected attenuation and path of each ray passing from the shutter system through the patient volume to the detector to deduce a measured fluence of each of the set of rays;
and
(e) comparing the measured fluence to the predetermined fluence of each ray to verify operation of the shutter system.

3 more elements

Dependencies are inferred from the claim text.

Method using post-patient radiation monitor to verify entrance radiation and dose in a radiation therapy machine

Life of this patent

Method using post-patient radiation monitor to verify entrance radiation and dose in a radiation therapy machine

Life of this patent

Abstract

Claims25