Physical factors affecting absorbed dose to the skin from cobalt-60 gamma rays and 25-MV x rays

Journal Article · Sun Jul 01 04:00:00 EDT 1979 · Med. Phys.; (United States)

OSTI ID:5993422

Gagnon, W F; Horton, J L

When there is an absence of scattering material adjacent to the skin on the exit side of a megavoltage beam the dose to the skin is less than would be calculated using depth dose tables or isodose distributions measured in ''semi-infinite'' phantoms. Ionization measurements using a thin-window parallel-plate chamber show that the dose at 4 mg/cm/sup 2/ from the exit surface is 14% to 16% less for cobalt-60 gamma rays and about 8% less for 25-MV x rays compared to the dose with full backscatter. As the angle of incidence increases the skin dose increases due to radiation scattered toward the surface. A method for the calculation of skin doses from tangential therapy beams is described.

• Research Organization: AAPM Radiological Physics Center, The University of Texas System Cancer Center, M. D. Anderson Hospital and Tumor Institute, 6723 Bertner Avenue, Houston, Texas 77030
• OSTI ID: 5993422
• Journal Information: Med. Phys.; (United States), Journal Name: Med. Phys.; (United States) Vol. 6:4; ISSN MPHYA
• Country of Publication: United States
• Language: English

Related Subjects

560151* -- Radiation Effects on Animals-- Man
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
BACKSCATTERING
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BODY
COBALT 60
COBALT ISOTOPES
DOSES
DOSIMETRY
ELECTROMAGNETIC RADIATION
GAMMA DOSIMETRY
GAMMA RADIATION
INTERMEDIATE MASS NUCLEI
INTERNAL CONVERSION RADIOISOTOPES
IONIZING RADIATIONS
ISODOSE CURVES
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
MEDICINE
MINUTES LIVING RADIOISOTOPES
NUCLEAR MEDICINE
NUCLEI
ODD-ODD NUCLEI
ORGANS
RADIATION DOSE DISTRIBUTIONS
RADIATION DOSES
RADIATIONS
RADIOISOTOPES
RADIOLOGY
RADIOTHERAPY
SCATTERING
SKIN
SKIN ABSORPTION
THERAPY
UPTAKE
X RADIATION
X-RAY DOSIMETRY
YEARS LIVING RADIOISOTOPES