Use of low-energy X-rays in the treatment of superficial nonmelanomatous skin cancers.

The Photon Radiosurgery System (PRS), developed by the Photoelectron Corporation in Lexington, Massachusetts, produces low-energy x-rays from the tip of a needle-like probe at a high dose-rate. This portable device can be located directly over the target volume, delivering a uniform dose while sparing surrounding normal structures. To evaluate its radiotherapeutic profile, a prospective phase I Food and Drug Administration trial was performed utilizing this device in the management of nonmelanomatous skin cancers. Target doses ranged from 10 Gray in one fraction to 30 Gray in three weekly fractions. Thirty-eight lesions in 18 patients were treated. The overall completed response rate for all histologies at 12 months was 83%. No significant acute or late morbidity was encountered. Our results to date demonstrate that low-energy x-rays produced by the PRS were as effective in managing nonmelanomatous skin tumors as other radiation treatment modalities without the need for cumbersome shielding or radiation precautions.