Large-field irradiation techniques in Germany: A DGMP Working Group survey on the current clinical implementation of total body irradiation, total skin irradiation and craniospinal irradiation.

In 2023, a Germany-wide survey on the current clinical practice of three different large field irradiation techniques (LFIT), namely total body irradiation (TBI), total skin irradiation (TSI) and craniospinal irradiation (CSI), was conducted covering different aspects of the irradiation process, e.g., the irradiation unit and technique, dosimetrical aspects and treatment planning as well as quality assurance. The responses provided a deep insight into the applied approaches showing a high heterogeneity between participating centers for all three large field irradiation techniques. The highest heterogeneity was found for TBI. Here, differences between centers were found in almost every aspect of the irradiation process, e.g., the irradiation technique, the prescription dose, the spared organs at risk and the applied treatment planning method. For TBI, the only agreement was found in the fractionation scheme (2 Gy/fraction, 2 fractions/day) and the dose reduction to the lung. TSI was the rarest of the three LFITs. For TSI, the only agreement was found in the use of 6 MeV when irradiating with electrons. The reported approaches of CSI were closest to standard radiotherapy, using no CSI-specific irradiation techniques or treatment planning methods. For CSI, the only agreement was found in the prescribed dose to the brain (50 - 60 Gy). When asking for future requirements, participating centers considered the lack of standardization as the most important future challenge and suggested to perform (retrospective) patient studies. The results of such studies can then serve as a basis for new and improved guidelines.