Dosimetric evaluation of a variable energy superficial X-ray machine with applications for endocavitary radiotherapy techniques.

This investigation presents the beam characteristics of a newly-marketed variable energy superficial X ray machine for radiotherapy. The X ray system hardware, including a high voltage generator, and console software allow for nine independent operator-selected X ray beams from 10-150 kVp. Filament current values are also independently variable; 1.0-13.0 mA for 90-150 kVp, and 1.0-30.0 mA for 10-90 kVp. The HVL's, effective energies, and radiation outputs for the nine combinations of kVp and mA are presented. In addition, percentage depth dose and beam uniformity results are presented as a function of cone size. Radiation output stability and reproducibility results are included. Discussion of adaptation of this X ray system to the Papillon technique for the treatment of rectal cancers is presented.