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When designing an entrance maze for a linear accelerator facility, it is useful to be able to estimate both the dose rate at the entrance and, in case further shielding is necessary, the energy spectrum of the scattered photons reaching the maze entrance. This study examines the applicability of the commonly used empirical formula contained in the National(More)
This paper reports the use of diodes as a quality control tool on more than 95% of patients undergoing megavoltage radiotherapy during the past 2 years. The paper describes a simple method for using the diodes, a number of possible pitfalls and a quality issue raised by the measurements. In general, the results have been reassuring with very few patients(More)
There is a need in conformal therapy, as in any radiation therapy, for adequate quality assurance of the treatment plan and the delivery of the treatment. This paper examines quality assurance of two methods of conformal treatment, on a cobalt treatment unit using computer control. Each of the two methods demonstrates a different aspect of computer(More)
There has been considerable interest in the measurement of bone density in the mandible, either to study bone resorption following tooth loss or to determine the relationship between mandibular and skeletal bone mineral density. Measurements mostly have been made on dental radiographs but more significant correlations between mandibular and skeletal bone(More)
The work reported examines the potential of using gamma-ray photon backscatter information to measure in vivo the percentage of fat in specific tissue volumes. 241Am gamma rays are used as the source and the backscatter detected with a hyperpure germanium detector, with ethanol (approximately 80% fat, 20% muscle) and water (muscle) being used as tissue(More)
The purpose of this study was to examine the potential of using backscatter information to assess regional body composition at selected sites. Two measurement techniques are examined: the measurement of the ratio of coherent to Compton scatter, and the measurement of the Compton scatter profile. Two possible applications are considered: the measurement of(More)
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