Performance characteristics of the Pantak Therapax-150 superficial X-ray treatment machine: measurements and calculations.

The beam and operating performance characteristics of a superficial X-ray unit, the Pantak Therapax-150 have been evaluated and benchmarked against the Monte Carlo code-MCNP. Parameters which were studied included beam quality, central axis depth dose and field uniformity for several applicator sizes and focal skin distances (FSDs) with the tube operating between 50 and 150 kVp accelerating potential. MCNP calculations were compared with five published qualities: 3.75 mm Al, 3.27 mm Al, 2.43 mm Al, 7.15 mm Al and 1.65 mm Cu half value layer (HVL). The unit has been found to provide beam characteristics similar to those reported for other superficial therapy machines. For most of the combinations of radiation qualities and applicators, good agreement between experiments an dcalculations was obtained. Calculated data when compared with other workers was not worse than 8.8%.