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.
University of Texas Health Science Center, Department of Radiology, Dallas 75235-9071.
D A
DA
Johnson
N C
NC
Ikoro
C H
CH
Chang
E C
EC
Scarbrough
P P
PP
Antich
D006801:Humans; D008953:Models, Anatomic; D010315:Particle Accelerators; D011827:Radiation; D011878:Radiotherapy / Q000295:instrumentation / Q000379:methods*; D011879:Radiotherapy Dosage