Comparison of dose distributions hippocampus in high grade gliomas irradiation with linac-based imrt and volumetric arc therapy: a dosimetric study

Abstract

The aim of this study was to assess the feasibility of sparing contralateral hippocampus during partial brain radiotherapy in high grade gliomas. 20 previously treated patients were replanned to 60 Gy in 30 fractions with sparing intensity-modulated radiotherapy (IMRT) and volumetric modulated arctherapy (VMAT) using the following planning objectives: 100 % of PTV covered by 95% isodose without violating organs at risk (OAR) and hot spot dose constraints. For each, standard intensity-modulated radiotherapy (IMRT) plans were generated, as well as sparing IMRT and VMAT plans which spared contralateral (hemispheric cases) hippocampus. When the three plans were compared, there was equivalent PTV coverage, homogeneity, and conformality. Sparing IMRT significantly reduced maximum, mean, V20, V30 and V40 hippocampus doses compared with standart IMRT and VMAT (p < 0.05). VMAT significantly reduced maximum left lens and mean eye doses compared with standart IMRT and sparing IMRT (p < 0.05). Brainstem, chiasm, left and right optic nerves, right eyes and lens doses were similar. VMAT significantly reduced monitor units compared with standart IMRT and sparing IMRT (p < 0.05). It is possible to spare contralateral hippocampus during PBRT for high grade gliomas using IMRT. This approach may reduce late cognitive sequelae of cranial radiotherapy.

Hippocampal sparing radiotherapy for glioblastoma patients: a planning study using volumetric modulated arc therapy

“…The other investigated parameters (target coverage, homogeneity index and conformity index) could be kept stable or even improved (dose homogeneity and conformity, whole brain dose). These results are in agreement with the results found in similar studies by Canyilmaz et al, who compared standard IMRT to hippocampal sparing IMRT and VMAT plans for 20 patients [ 17 ], and Marsh et al who compared standard IMRT plans to IMRT plans with sparing of the contralateral neural stem cell compartment, hippocampus and limbic circuit for 5 patients [ 18 ]. The planning strategy in these studies differed from the concept used in our planning study.…”

MRI-Guided Clinical 6-MV Radiosensitization of Glioma Using a Unique Gadolinium-Based Nanoparticles Injection

“…Although radiotherapy is presently the most efficient treatment against brain tumors, it is primarily limited in its ability to deliver therapeutic doses to target tumor volume while minimizing damages to the surrounding healthy tissues. In addition to the modulation of radiation exposure parameters and/or geometry [2,3] and to the combination with chemotherapy, one attractive approach to overcome this limitation is the use of new therapeutic agents (molecules or nanoparticles [NPs]) that sensitize cancer cells to ionizing radiation (i.e., dose enhancers and radiosensitizers). In particular, the concept of the dose enhancers is to increase the radiobiological effect of high-energy radiation inside the tumor by incorporating high-density and high atomic number elements thus locally significantly increasing the dose effect delivered by the particles beams [4][5][6][7][8].…”

Benefits and difficulties during brain radiotherapy planning with hippocampus sparing

“…In certain clinical situations, i.e. in the presence of an extensive oedema or central tumour location, especially around the brain stem, many authors suggest shielding only one hippocampus -on the opposite side of the tumour site [20,42,43]. It is worth adding that in children primary brain tumours are diagnosed much more frequently than in adults, and the procedure of hippocampal protection in these cases has a special clinical value during RT planning [44,45].…”