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Characteristics of the high-energy photon beam of a 25-MeV accelerator

Journal Article · · Med. Phys.; (United States)
DOI:https://doi.org/10.1118/1.596163· OSTI ID:5732011
The CGR Saturne 25 is an isocentrically mounted standing wave medical linear accelerator that produces dual-energy photon beams and a scanned electron beam with six selectable energies between 4 and 25 MeV. The highest energy photon beam is nominally referred to as 23 MV. For this beam the mean energy of the accelerated electron beam on the 1.3 radiation length (4 mm) tungsten x-ray target is found to be approximately 21 MeV, with the energy acceptance stated to be +- 5%. The electron beam traverses a 270/sup 0/ bending magnet upstream of the x-ray production target. The resulting bremsstrahlung beam passes through a combination steel and lead flattening filter, 4-cm maximum thickness. Dosimetric data for the 23-MV beam are presented with respect to rectangular field output factor, depth of maximum dose as a function of field size, surface and buildup dose, central axis percent depth dose, tissue-phantom ratios, beam profile, applicability of inverse square, and block transmission. Some data are also presented on the effect of different flattening filter designs on apparent beam energy.
Research Organization:
University of Southern California, Department of Radiation Oncology, Kenneth Norris Jr. Cancer Hospital and Research Institute, Los Angeles, California 90033
OSTI ID:
5732011
Journal Information:
Med. Phys.; (United States), Journal Name: Med. Phys.; (United States) Vol. 15:1; ISSN MPHYA
Country of Publication:
United States
Language:
English