Precise Mapping of Skin Dose to Avoid Further Radiation-Induced Epilation

Abstract

Although several cases of radiation-induced skin injury (RSI) have been reported in association with neurointerventional procedures, in most cases the absorbed doses to these regions are not measured directly; therefore, we built the first direct measurement system that enables the ideal dosimetry for entrance skin dose (ESD) during neurointerventional procedures to be easily determined. This system was then applied to a patient who underwent long and repetitive procedures to establish the efficacy of precise mapping of ESDs using a number of radiophotoluminescent glass dosimeters (RPLDs) with the aim of avoiding RSI. A previously healthy 55-year-old man underwent two transvenous embolizations for dural arteriovenous fistula in the right cavernous sinus, with an interval of 2 months. To measure ESDs throughout the procedures, the patient wore a fitted dosimetry cap made of a thin stretchable material that closely covers the head and neck and contains 60 RPLD chips with sufficient radiolucency for fluoroscopy. After the first procedure, temporal epilation occurred in the occipital region. Precise mapping of ESDs revealed that this region was exposed to 5.4 Gy, the maximum dose for this procedure. In the first procedure, the X-ray tube was generally positioned straight for an optimal posterior- anterior view; however, in the second procedure we intermittently used the second-best position to prevent further RSI. In this position, the maximum ESD was 1.1 Gy in the right posterior- temporal region and the epilation site was exposed to ≤0.8 Gy. Thus, the patient did not develop any further epilation and was completely free from RSI by 3 months after the second procedure. We conclude that direct dosimetry using multiple RPLDs can accurately reveal the maximum ESD and that precise information regarding ESD can prevent further RSIs from subsequent procedures.