Akademik Veri Yönetim Sistemi
INTERNATIONAL CONFERENCE ON RADIATION IN VARIOUS FIELDS OF RESEARCH, Herceg Novi, Karadağ, 13 - 17 Haziran 2022, ss.75
Purpose: In total body irradiations, it is not easy to have homogenous dose distribution because of inhomogeneous body shape and tissue density variations. In radiotherapy it is essential to save critical organ and to get homogeneous dose distribution in planning target volume (PTV) The purpose of this study is to compare different treatment planning system (TPS) algorithms in terms of critical organ doses, PTV coverage and dose homogeneity on Tomotherapy and VMAT technique for TBI treatments.
Materials and Methods: In this study, arms were added to the male phantom using rice to simulate the whole body geometrically. The male phantom with arms was immobilized by a vacuum bed and 3 mm CT images were received. The entire body, lungs, lens, and kidneys were contoured with a 3 mm margin and PTV was created. For TBI treatments, 7-10 Gy lung mean dose is admissible and the midpoint of lungs is seen as the reference point. Lens dose is admissible under 5 Gy for all treatments. In this study, dose constraints for organs at TPS were; mean coverage of 90% PTV is 12 Gy, maximum lens doses were 4 Gy, maximum lung doses were 8 Gy, maximum kidney doses were 7 Gy. PTVmax, lensmax, lungsmean, and kidneysmean doses were evaluated on VoLo v2.0.4, Eclipse v8.9 TPS, and Eclipse v15.6 TPS Algorithms. The homogeneity index (HI) was also taken into consideration.
Results: Results of this study showed that VoLo v2.0.4 and Eclipse v15.6 Algorithms have close critical organ doses, but Eclipse v8.9 was higher than others. Mean lung doses were 7.60/7.71 Gy (right/left) for VoLo TPS, 9.07/9.23 Gy(right/left) for Eclipse v15.6 TPS, 9.36/9.48 Gy (right/left) for Eclipse v8.9 TPS. Mean kidney doses were 6.70/6.51 Gy(right/left) for VoLo TPS, 6.46/6.43 Gy (right/left) for Eclipse 15.6 TPS, 8.19/8.21 Gy (right/left) for Eclipse v8.9 TPS. HI values were 0.16 for VoLo v2.0.4 TPS, 0.29 for Eclipse v15.6 TPS, and 0.24 for Eclipse v8.9 TPS. Maximum lens doses were 2.94/3.18 Gy (right/left) for VoLo TPS, 2.24/2.49 Gy (right/left) for Eclipse v15.6 TPS, 4.86/5.46 Gy (right/left) for Eclipse v8.9 TPS.
Conclusion: At the end of the study, it was seen that Tomotherapy VoLo v2.0.4 TPS and VMAT Eclipse
v15.6 TPS algorithms had close critical organ doses, but Eclipse v8.9 resulted with higher doses on organs.
HI value obtained by Tomotherapy was more desirable beside VMAT algorithms