Improved lung dose calculation using tissue--maximum ratios in the Batho correction

Journal Article · Tue May 01 04:00:00 EDT 1984 · Med. Phys.; (United States)

DOI:https://doi.org/10.1118/1.595495· OSTI ID:7094911

El-Khatib, E; Battista, J J

We have reexamined the Batho power law for computing the dose within and beyond lung irradiated with small and large fields of cobalt-60 and 6-MV x rays. Using slab phantoms consisting of two materials, agreement between calculated and measured doses was within 2% inside lung for 6-MV x irradiation, but much poorer (9%) for cobalt-60 irradiation. For cobalt-60 irradiation, tissue--air ratios (TARs) were used initially in the Batho equation, while for 6-MV x rays, tissue--maximum ratios (TMRs) were used. When we substituted TMR values instead of TAR values for cobalt-60, we found marked improvement by nearly 5% in the accuracy of dose calculated within lung. This was confirmed by numerical comparison of the Batho expression with an analytic solution of the primary and first-scattered radiation. We therefore encourage the use of TMRs for cobalt-60 radiation, expecially for larger radiation fields, and provide measured data tables for field sizes up to 50 x 50 cm/sup 2/, and depths up to 30 cm. In addition to unifying the dosimetry for all megavoltage irradiation, this approach improves the accuracy of doses calculated within lung.

• Research Organization: Department of Medical Physics, Cross Cancer Institute, 11560 University Avenue, Edmonton, Alberta, Canada T6G 1Z2
• OSTI ID: 7094911
• Journal Information: Med. Phys.; (United States), Journal Name: Med. Phys.; (United States) Vol. 11:3; ISSN MPHYA
• Country of Publication: United States
• Language: English

Related Subjects

550603 -- Medicine-- External Radiation in Therapy-- (1980-)
61 RADIATION PROTECTION AND DOSIMETRY
62 RADIOLOGY AND NUCLEAR MEDICINE
655003* -- Medical Physics-- Dosimetry
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BODY
COBALT 60
COBALT ISOTOPES
CORRECTIONS
DOSIMETRY
ELECTROMAGNETIC RADIATION
GAMMA DOSIMETRY
GAMMA RADIATION
INTERMEDIATE MASS NUCLEI
INTERNAL CONVERSION RADIOISOTOPES
IONIZING RADIATIONS
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
LUNGS
MINUTES LIVING RADIOISOTOPES
MOCKUP
NUCLEI
ODD-ODD NUCLEI
ORGANS
PHANTOMS
RADIATION DOSE DISTRIBUTIONS
RADIATIONS
RADIOISOTOPES
RESPIRATORY SYSTEM
STRUCTURAL MODELS
X RADIATION
X-RAY DOSIMETRY
YEARS LIVING RADIOISOTOPES