Surface dose for megavoltage photon beams outside the treatment field

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

DOI:https://doi.org/10.1118/1.595362· OSTI ID:6537324

Starkschall, G; George, F J; Zellmer, D L

Measurements made on photon beams from four different radiotherapy machines have demonstrated that skin dose several centimeters outside the boundary of a treatment field may be as much as 20% of the central axis maximum dose. This surface dose has been measured for an AECL Theratron 80, Siemens Mevatron VI, Varian Clinac 20, and CGR Sagittaire for distances up to 12 cm outside the field boundary and for depths up to the depth of maximum central axis dose. This dose has also been measured as a function of field size and of source-to-skin distance. For the lower energy photon beams, this radiation is significantly attenuated in the first 2-3 mm of tissue, while for higher energy beams, a buildup phenomenon with a dmax of 2-3 mm is observed. The magnitude of this radiation is approximately linearly dependent upon field dimension for all energies.

• Research Organization: Univ. of Kansas Medical Center, Kansas City
• OSTI ID: 6537324
• Journal Information: Med. Phys.; (United States), Journal Name: Med. Phys.; (United States) Vol. 10:6; 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.
ACCELERATORS
BEAMS
BODY
BUILDUP
DOSES
MEDICINE
NUCLEAR MEDICINE
ORGANS
PHOTON BEAMS
RADIATION DOSES
RADIOLOGY
RADIOTHERAPY
SKIN
THERAPY