ESTRO 2021 Abstract Book

S625

ESTRO 2021

Maastricht, The Netherlands

Purpose or Objective In 2014 a Belgian/Dutch NCS task group was formed to develop guidelines on clinical practice of Total Body Irradiation (TBI) and Total Skin Irradiation (TSI). First, a survey was performed to investigate the current clinical practice. Materials and Methods An electronic survey was sent out to all Dutch and Belgian radiation oncology institutions in 2014. The survey consisted of 5 general, and 49 TBI- and 38 TSI-related questions. Seventeen (=100%) institutions perform TBI of which 4 also practice TSI. An update of the survey was performed in 2020 because several institutions were considering innovating their TBI technique. Results Several studies showed that clinical practice of TBI varies a lot among institutions, which was confirmed in the present study. This is reflected in a wide variety of techniques and fractionation schemes (see table). Although the pace of introduction is slow compared to other treatment techniques, the number of institutions reconsidering their TBI techniques increases. Besides implementing CT-based treatment planning, also digital verification of patient position (at large SSD) and Field-in-Field/VMAT techniques are reconsidered. TSI is practiced much more similarly among institutions since decades. Critical organs, e.g., lungs, eyes, kidney and others are shielded from irradiation in multiple institutions, depending on fractionation schemes used. In general, for total doses higher than 6 Gy shielding of organs at risk is practiced. Lung shielding is performed in 11 out of 17 institutions: 9 institutions shield lungs with individualized Cerrobend blocks, the other 2 with MLC. Eyes are shielded individually in 1 institution and standardized in 4 institutions, and 1 institution also blocks both kidneys individually. One institution uses Lucite plates to reduce the dose to the head if exceeding, e.g., 110% of the prescribed dose. Another institution also shields ankles and knees in order to improve dose homogeneity. Two institutions do not use any shielding. Four institutions apply real-time imaging by EPID technology at large SSD to verify patient position during treatment.