Effect of collimator backscatter radiation on photon output of linear accelerators
The field-size dependence of the photon output of linear accelerators in air has been attributed in part to changes in the amount of radiation backscattered from the collimator jaws into the dose monitor chamber. This possible effect was investigated for a variety of accelerators with energies from 4- to 15-MV by measuring the monitor unit rate (MU/min) for different collimator openings. This measurement was made without dose rate feedback control, i.e., with constant electron beam current in the accelerator. The monitor unit rate was independent of collimator setting for all machines tested. Hence, it is concluded that backscattered radiation from the collimator jaws into the dose monitor chamber does not contribute to the variation of output with field size.
- Research Organization:
- Department of Radiation Oncology, St. Jude Children's Research Hospital, Memphis, Tennessee 38101
- OSTI ID:
- 6767705
- Journal Information:
- Med. Phys.; (United States), Vol. 14:2
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
62 RADIOLOGY AND NUCLEAR MEDICINE
LINEAR ACCELERATORS
RADIOTHERAPY
BACKSCATTERING
COLLIMATORS
DOSE RATES
MONITORING
PHOTON BEAMS
ACCELERATORS
BEAMS
MEDICINE
NUCLEAR MEDICINE
RADIOLOGY
SCATTERING
THERAPY
430303* - Particle Accelerators- Experimental Facilities & Equipment
550603 - Medicine- External Radiation in Therapy- (1980-)