Investigation of alternative means to accomplish the goals of biennial calibration of ionization chambers

Technical Report · Wed May 01 04:00:00 EDT 1985

OSTI ID:5664442

Cameron, J R; DeWerd, L A; Goetsch, S J; Price, J C

The research described in this report was performed to investigate the feasibility of a mailed dosimetry system as an alternative method of achieving the goals of the present US Nuclear Regulatory Commission requirement that ionization chambers used for calibration of cobalt-60 teletherapy units be calibrated every two years. Both thermoluminescent dosimeters (TLD's) and diode detector units were used in this study. A total of 20 hospitals in the states of Illinois, Iowa and Wisconsin participated in a program in which this dosimetry package was sent to each institution on three separate occasions. The physicist, physician or chief technologist was asked to deliver 1.50 Gray (150 rads) to the device, assuming the device was equivalent in radiation absorption characteristics to human tissue. A treatment field size of 10cm by 10cm was chosen and the institution was requested to use their clinical source-to-surface distance. The accuracy of the beam localization as indicated by the coincidence of the light field with the radiation field was measured as well. The criterion for accuracy of dose delivery was +-5% and the criterion for light field and radiation field coincidence was +-3.0mm. Only two hospitals during the course of the study had both unacceptable diode meter and TLD readings simultaneously. Only one hospital had a disagreement of more than 3mm between the light field and the radiation field. It is recommended that such a mailed dosimetry package be considered as an alternative to the present NRC requirement for biennial calibration of ionization chambers used to calibrate cobalt-60 teletherapy sources. 5 refs., 5 tabs.

• Research Organization: Wisconsin Univ., Madison (USA). Dept. of Medical Physics
• OSTI ID: 5664442
• Report Number(s): NUREG/CR-4131; ON: TI85901477
• 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
BUILDINGS
CALIBRATION
COBALT 60
COBALT ISOTOPES
COST BENEFIT ANALYSIS
DOSIMETRY
EQUIPMENT
FEASIBILITY STUDIES
HOSPITALS
INTERMEDIATE MASS NUCLEI
INTERNAL CONVERSION RADIOISOTOPES
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
MATERIALS
MEDICAL ESTABLISHMENTS
MINUTES LIVING RADIOISOTOPES
NUCLEI
ODD-ODD NUCLEI
RADIOISOTOPES
THERMOLUMINESCENT DOSIMETRY
TISSUE-EQUIVALENT MATERIALS
X-RAY EQUIPMENT
YEARS LIVING RADIOISOTOPES