Surface Mold Brachytherapy for Mycosis Fungoides of the Foot

Abstract

The purpose of our innovation was to develop a method of conformal irradiation to the skin of the ankle and foot which, in the past, has proven challenging to treat with external beam radiotherapy. A 51-year-old male with previous history of mycosis fungoides presented with a patch of mycosis fungoides in a previously irradiated region of his left ankle and foot. We elected to treat this lesion with HDR surface mold brachytherapy. On examination, there was an erythematous patch on the left ankle and foot involving the dorsum, lateral aspect, Achilles region and medial malleolar fossa, sparing the sole. The CTV was identified and a thermoplastic mold of the foot was created. 14 flexible brachytherapy catheters were affixed to the mold and a planning CT was performed. The prescription was 2500 cGy in 10 daily fractions to the skin surface. The total skin target volume to be treated was 50.23 cm3. CTV D90 was 97.2% demonstrating excellent target coverage. The plan also displayed good homogeneity, with mean, maximum and minimum skin doses of 102.6%, 115.2% and 93.6% and a heterogeneity index of 0.97. The surface mold performed well during treatments and was sufficiently durable. In this case report, we have applied surface mold brachytherapy to region of the body that in the past has proven challenging to treat with external beam radiotherapy. We have demonstrated that surface mold brachytherapy is a versatile method of radiotherapy that can achieve excellent target coverage and homogeneity while maximizing normal tissue sparing.