Session Item

To investigate the target volumes, the doses received by heart and carotid arteries exposed to the different radiation doses using three-dimensional conformal radiotherapy (3DCRT), helical tomotherapy (HT), and volumetric arc therapy (VMAT) techniques in patients with early supradiaphragmatic Hodgkin lymphoma (HL).

Treatment plans of patients were reconstituted retrospectively. The target volumes, the doses received by the heart and carotid arteries when 20 Gy and 30 Gy radiation doses that were given according to the definition of involved field (IFRT) and involved node (INRT) using 3DCRT, HT and VMAT techniques in patients with HL, were obtained. Plans were also taken for CMS XIO 5.00 for 3DCRT, MONACO 5.1 for VMAT, and HiART TPS for HT. In VMAT planning, 2 full arches were used in the presence of axillary involvement, and butterfly technique was used in those without involvement.

There were a total of 19 patients (13M ,6F). There was a significant difference between 3DCRT, HT and VMAT techniques for V95%, Dmean, D2% in PTVIFRT at both doses given (p<0.001). HT created more conformal plan compared to other techniques, and VMAT technique both kept the maximum possible dose to a minimum providing more homogeneous dose distribution (p<0.001; p<0.001). The VMAT technique for conformity index was better (p<0.001), while the HT technique provided more homogeneous dose distribution (p<0.001) according to the PTVINRT. There was no statistically significant difference in the Dmean, V10, V15, V20 values of the heart between the two doses used. While the prescribed doses was 20 Gy and 30 Gy, there was a statistically significant difference for the right carotid artery Dmean according to the definition of IFRT (p=0.006 and p=0.005, respectively), and a more appropriate DVH was obtained usingVMAT technique. No statistically significant difference was found according to the definition of INRT. With VMAT and HT techniques, 18% and 28% reductions were obtained compared to 3DCRT with all dose values for the heart, respectively. When the volume to be irradiated was kept constant and the dose given was reduced from 30 Gy to 20 Gy, a decrease in Dmean value of the heart was achieved by 33%, 33% and 35% in 3DCRT, HT and VMAT techniques, respectively. Similarly, when the defined dose was kept constant and the irradiated volume decreased, the Dmean value of the heart decreased. With regard to the carotid artery doses, the mean values of the carotid arteries were reduced by 53%, 45% and 53% for 3DCRT, HT and VMAT, respectively.

In all techniques, the target volume received the desired dose, but with the HT technique, PTV’s were ensured to receive the most appropriately prescribed dose, while the max dose was obtained at minimum in VMAT technique. Although advanced rotational techniques such as HT and VMAT can be chosen for cardiac side effects, the INRT technique, which provides volume reduction, has been found to be more effective in preventing long-term side effects.