Characteristics of an 18 MV photon beam from a Therac 20 Medical Linear Accelerator

Journal Article · · Med. Phys.; (United States)

DOI:https://doi.org/10.1118/1.594833· OSTI ID:5283557

Patterson, M S; Shragge, P C

The 18 MV photon beam characteristics of a Therac 20 Medical Linear Accelerator manufactured by Atomic Energy of Canada Ltd, are presented. Tissue phantom ratios (TRP's) and percent depth dose data are given; for a 10 x 10 cm field, the percent depth dose at a depth of 10 cm is 78.5 (SSD 100 cm). The relative dose factors (RDF'S) are given and are analyzed to elucidate the relative contributions from phantom scatter, collimator scatter, and backscatter from the top of the collimators into the monitor chambers. The effect of field size and depth on the penumbra is described. Crossplots of the beam at a depth of 5 cm indicate that the flattening filter could be improved; there are hot spots of 108% near the corners of 40 x 40 fields.

• Research Organization: Ontario Cancer Foundation, Kingston
• OSTI ID: 5283557
• Journal Information: Med. Phys.; (United States), Vol. 8:3
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
61 RADIATION PROTECTION AND DOSIMETRY
LINEAR ACCELERATORS
BEAM OPTICS
DEPTH DOSE DISTRIBUTIONS
PHANTOMS
PHOTON BEAMS
RADIATION DOSES
RADIOTHERAPY
ACCELERATORS
BEAMS
DOSES
MEDICINE
MOCKUP
NUCLEAR MEDICINE
RADIATION DOSE DISTRIBUTIONS
RADIOLOGY
SPATIAL DOSE DISTRIBUTIONS
STRUCTURAL MODELS
THERAPY
550603* - Medicine- External Radiation in Therapy- (1980-)
655003 - Medical Physics- Dosimetry