Analysis of dosimetric parameter on craniospinal irradiation with Helical Tomotherapy (HT), 3D Conformal Radiotherapy (3DCRT), and Intensity Modulated Radiotherapy (IMRT)

Traditional craniospinal irradiation consists of a large treatment area divided into several fields that can create dose overlaps in the inter-field junction. This analysis compares the dosimetric parameter of craniospinal irradiation with HT, 3DCRT, and LINAC-based IMRT and find the optimal technique in terms of dose distribution, organ-sparing, and body radiation exposure. In our hospital, 3DCRT, IMRT, and HT plan were made from CT data of 10 patients indicated for craniospinal irradiation, with a total dose of 36 Gy in 20 fractions. Cranial and spinal PTV coverage was evaluated using the Conformity Index (CI) and Homogeneity Index (HI). Dose received by critical organs, body-wide radiation exposure, number of Monitor Units (MU), and beam on duration were recorded and compared. In cranial PTV, HT and IMRT had better HI and CI compared to 3DCRT with no significant difference between IMRT and HT. In spinal PTV, HT had better HI and CI compared to IMRT and 3DCRT. 3DCRT has the highest mean dose in most of the critical organs, while HT has the highest whole-body radiation exposure, highest number of MU, and the longest beam on duration. For doses in inter-field junction, there is no statistically significant difference between 3DCRT and IMRT techniques. HT technique achieved the highest HI and CI but also had the highest body-wide radiation exposure, highest MU number, and longest beam on duration, in contrast to 3DCRT Proper consideration of the technique used in craniospinal irradiation is important to prevent late side effects, such as secondary malignancy.