Dosimetry of 24-MV x rays from a linear accelerator. 1987

G Krithivas, and S N Rao

Dosimetric characteristics of a 24-MV photon beam produced by a Varian Clinac 2500 linear accelerator are presented. Particular attention is paid to measurements and applications relating to depth of maximum dose and scatter correction factors. New experimental methods were adopted to investigate scatter factors for field sizes ranging from 5 X 5 to 40 X 40 cm. For the largest field investigated, a 3% phantom scatter factor relative to a 10 X 10 cm field was determined. From the study, clinically useful scatter-phantom ratios were generated. The study also demonstrated that the estimated correction factors for scatter in a medium caused negligible changes (approximately equal to 0.1%) on the percent depth-dose values derived from the measured tissue-phantom ratio (TPR) data. The paper also quantitatively compares results obtained for dosimetric parameters like scatter output, tissue-phantom ratio, and percent depth-dose with those obtained from similar machines used for radiotherapy. Measured data relating to these parameters are expressed by taking a reference depth of 8 g/cm2 in a medium for normalization purposes and its importance discussed. Additional measurements presented in this work include beam quality and collimator effect on dose rate. Phantoms of various sizes and materials and a variety of detectors were used throughout the investigation.

UI MeSH Term Description Entries
D010315 Particle Accelerators Devices which accelerate electrically charged atomic or subatomic particles, such as electrons, protons or ions, to high velocities so they have high kinetic energy. Betatrons,Linear Accelerators,Accelerator, Linear,Accelerator, Particle,Accelerators, Linear,Accelerators, Particle,Betatron,Linear Accelerator,Particle Accelerator
D011874 Radiometry The measurement of radiation by photography, as in x-ray film and film badge, by Geiger-Mueller tube, and by SCINTILLATION COUNTING. Geiger-Mueller Counters,Nuclear Track Detection,Radiation Dosimetry,Dosimetry, Radiation,Geiger Counter,Geiger-Mueller Counter Tube,Geiger-Mueller Probe,Geiger-Mueller Tube,Radiation Counter,Counter Tube, Geiger-Mueller,Counter Tubes, Geiger-Mueller,Counter, Geiger,Counter, Radiation,Counters, Geiger,Counters, Geiger-Mueller,Counters, Radiation,Detection, Nuclear Track,Dosimetries, Radiation,Geiger Counters,Geiger Mueller Counter Tube,Geiger Mueller Counters,Geiger Mueller Probe,Geiger Mueller Tube,Geiger-Mueller Counter Tubes,Geiger-Mueller Probes,Geiger-Mueller Tubes,Probe, Geiger-Mueller,Probes, Geiger-Mueller,Radiation Counters,Radiation Dosimetries,Tube, Geiger-Mueller,Tube, Geiger-Mueller Counter,Tubes, Geiger-Mueller,Tubes, Geiger-Mueller Counter
D012542 Scattering, Radiation The diversion of RADIATION (thermal, electromagnetic, or nuclear) from its original path as a result of interactions or collisions with atoms, molecules, or larger particles in the atmosphere or other media. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed) Radiation Scattering,Radiation Scatterings,Scatterings, Radiation

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