Use of a PLA sleeve to remove electron enhancement in superficial X-ray therapy.

A newly installed superficial X-ray unit was found to produce enhanced electron dose at the skin surface. The ACPSEM kilovoltage dosimetry recommendations suggest using nail varnish within the treatment cones as a method to reduce this dose. In this study, a 3D PLA sleeve was produced and used as an alternative to the nail varnish for energies between 55 and 100 kV. Further, plastic wrap was also investigated as an alternative method to reduce dose. It was found that a 1 mm printed sleeve, inserted into the treatment cone sufficiently reduced the enhanced dose as measured with a thin-window Exradin chamber to within 3.3% of the dose measured with a Farmer-type ionisation chamber. The use of plastic wrap also reduced the enhanced dose, but impracticalities in its use make it non-viable for routine clinical use.