Comparison of bolus electron conformal therapy plans to traditional electron and proton therapy to treat melanoma in the medial canthus

Abstract

Electrons can be used to treat superficial skin lesions given their finite depth; however, treating irregular surfaces with varying depths may be challenging. Traditionally a machinist can design customized devices to improve the dose coverage and shield nearby organs; however, the precision of handmade devices can be worrisome when treating nearby critical structures. Bolus electron conformal therapy (BolusECT) was introduced in the 1990s using an automated process of computer numerical control (CNC) milling machines to form a variable-thickness bolus from machinable wax using coordinate specification from computed tomography (CT) scans.1,2 The increased speed of CNC milling technology and advent of 3-dimensional (3D) printing have expanded the number of options for treating superficial lesions.1–4 Proton therapy can also treat variable depth lesions, but is not widely available. We present 3 treatment options available at our institution to treat a challenging case involving the medial canthus: handmade uniform bolus with skin collimator, automated variable-thickness bolus with skin collimator, and proton therapy.