Properties of the 18-MV photon beam from a dual energy linear accelerator.
The beam characteristics of the 18-MV photon beam of a Varian Clinac 1800 are presented. The clinically relevant parameters of central axis depth dose, tissue-phantom ratios, peak-scatter factors, and relative output factors are discussed and compared to 18-MV beam data previously reported. The nominal beam energy was found to be 18.3 +/- 0.8 MV on the central axis. The beam symmetry and uniformity meet the manufacturer's specifications. The inverse-square law is applicable within 1.4% over the clinically useful range of distances and field sizes. An empirical fit equation for the central axis depth dose is presented.
Johnson
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DA
University of Texas Health Science Center, Department of Radiology, Dallas 75235-9071.
Ikoro
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NC
Chang
C H
CH
Scarbrough
E C
EC
Antich
P P
PP
D006801:Humans; D008953:Models, Anatomic; D010315:Particle Accelerators; D011827:Radiation; D011878:Radiotherapy / Q000295:instrumentation / Q000379:methods*; D011879:Radiotherapy Dosage