Accuracy of the Burns equation for stopping-power ratio as a function of depth and R50.
The accuracy of the Burns et al. equation [Med. Phys. 23, 489-501 (1996)] for the Spencer-Attix water to air stopping-power ratio as a function of depth in a water phantom and electron beam quality in terms of R50 is investigated by comparison to the original data on which this fit was based. It is shown that using this equation provides dose estimates on the central axis in a clinical electron beam that are accurate to within 1% of dose maximum for all 24 clinical beams investigated except very close to the surface in swept beams. In contrast, the error in the dose as a percentage of the local dose is much higher for values of the depth/R50 greater than 1.2.
Rogers
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DW
Physics Department, Carleton University, Ottawa, Ontario K1S 5B6, Canada. drogers@physics.carleton.ca
D000465:Algorithms; D001822:Body Burden; D003198:Computer Simulation; D004583:Electrons / Q000627:therapeutic use*; D006801:Humans; D018499:Linear Energy Transfer; D008954:Models, Biological; D011868:Radioisotopes / Q000032:analysis* / Q000627:therapeutic use; D011874:Radiometry / Q000379:methods* / Q000592:standards / Q000706:statistics & numerical data; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods* / Q000592:standards / Q000706:statistics & numerical data; D012015:Reference Standards; D012062:Relative Biological Effectiveness; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013679:Technology, Radiologic / Q000592:standards / Q000706:statistics & numerical data
D011868:Radioisotopes