Relative electron beam measurements: Scaling depths in clear polystyrene to equivalent depths in water

Journal Article · Fri May 01 04:00:00 EDT 1987 · Med. Phys.; (United States)

DOI:https://doi.org/10.1118/1.596058· OSTI ID:6598281

Ten Haken, R K; Fraass, B A

For purposes of mean incident energy determination and the accrual of consistent treatment planning data, measurements of relative ionization or dose made in clear polystyrene must be scaled in depth to produce depth-ionization or depth-dose curves equivalent to what would have been measured in water. Recommendations from various protocols for clear polystyrene to water depth scaling factors differ by as much as 5%. Here, central axis measurements of relative ionization as a function of depth have been made with parallel-plate chambers both in a popular clear polystyrene phantom of density 1.045 g/cm/sup 3/ and in water. Perturbation and displacement corrections were thus minimized. Both depth-ionization and depth-dose curves were formed for electron beams with nominal incident energies between 6 and 20 MeV and field sizes from 6 cm x 6 cm to 15 cm x 15 cm. Comparisons of the depths for 50% relative reading and practical range between the two phantoms yield average empirical scaling factors of 0.990 and 1.002, respectively.

• Research Organization: Department of Radiation Oncology, University of Michigan Medical School, Ann Arbor, Michigan 48109
• OSTI ID: 6598281
• Journal Information: Med. Phys.; (United States), Journal Name: Med. Phys.; (United States) Vol. 14:3; ISSN MPHYA
• Country of Publication: United States
• Language: English

Related Subjects

61 RADIATION PROTECTION AND DOSIMETRY
655003* -- Medical Physics-- Dosimetry
DEPTH DOSE DISTRIBUTIONS
DOSIMETRY
ELECTRON DOSIMETRY
HYDROGEN COMPOUNDS
MATERIALS
MOCKUP
ORGANIC COMPOUNDS
ORGANIC POLYMERS
OXYGEN COMPOUNDS
PETROCHEMICALS
PETROLEUM PRODUCTS
PHANTOMS
PLASTICS
POLYMERS
POLYOLEFINS
POLYSTYRENE
POLYVINYLS
RADIATION DOSE DISTRIBUTIONS
SPATIAL DOSE DISTRIBUTIONS
STRUCTURAL MODELS
SYNTHETIC MATERIALS
WATER