Lung dose corrections for 6- and 15-MV x rays

Journal Article · Wed May 01 04:00:00 EDT 1985 · Med. Phys.; (United States)

DOI:https://doi.org/10.1118/1.595691· OSTI ID:5735124

Mackie, T R; El-Khatib, E; Battista, J; Scrimger, J; Van Dyk, J; Cunningham, J R

We have measured the radiation dose in simple heterogeneous phantoms and compared our results with those obtained by various methods of computation. Dose data were obtained both within and distal to simulated regions of lung in order to test the ratio of tissue--air ratios (TAR), Batho, and equivalent TAR methods. These procedures are used routinely in manual and computer-aided planning of radiation therapy, but have been validated primarily for cobalt-60 radiation. Tests performed with 6- and 15-MV x rays reveal that incorrect doses can be computed within or near to a low-density medium, particularly when the field size is small. In these cases, electronic equilibrium is not achieved in the lateral direction, thereby violating an implicit assumption of all the above calculation methods. We quantify the errors in dose calculation for simple slab phantoms, and support our interpretation with a Monte Carlo simulation in which the energy transported by charged particles away from sites of x-ray interactions is considered directly.

• Research Organization: Department of Medical Physics, Cross Cancer Institute, 11560 University Avenue, Edmonton, Alberta, Canada T6G 1Z2
• OSTI ID: 5735124
• Journal Information: Med. Phys.; (United States), Journal Name: Med. Phys.; (United States) Vol. 12:3; ISSN MPHYA
• Country of Publication: United States
• Language: English

Related Subjects

61 RADIATION PROTECTION AND DOSIMETRY
655003* -- Medical Physics-- Dosimetry
BODY
DOSES
DOSIMETRY
LUNGS
MEDICINE
MOCKUP
NUCLEAR MEDICINE
ORGANS
PHANTOMS
RADIATION DOSE DISTRIBUTIONS
RADIATION DOSES
RADIOLOGY
RADIOTHERAPY
RESPIRATORY SYSTEM
STRUCTURAL MODELS
THERAPY
X-RAY DOSIMETRY