Whole body electron therapy in mycosis fungoides

Whole body electron irradiation is frequently used in the treatment of mycosis fungoides, a disease which may involve large areas of the body surface. The major technological problems encountered in whole body electron therapy (WBET) are delivery of radiation to a layer 10-15 mm deep uniformly over all of the patient's body and minimizing contamination of the beam by Brems-strahlung X-rays generated in electron interactions with matter located between the electron source and the patient. In the most common method of WBET, patients are irradiated by beams of 3-4 MeV electrons while standing at a distance of about three meters from the electron source to produce large treatment fields. At this distance the maximum intensity of the standard 4 MeV electron beam from our Philips SL 75/10 Linac is only about 10 rad/min while the X-ray contamination increases from a tolerable value below 2% at 1 meter to about 8%. These conditions are not acceptable, hence a long distance method is not suitable for our machine. An alternative procedure is to treat the patient at a shorter distance with an electron beam that scans the surface of his body. Our technique provides a practical solution to the clinical requirements with respect to uniformity of electron dose and low X-ray contamination. Its implementatin does not require special equipment or modifications of the Linac.