A comparison of dosimetric parameters between tomotherapy and three-dimensional conformal radiotherapy in rectal
Mina Yu1, Joo Hwan Lee, Hong Seok Jang
1Department of Radiation Oncology, St, Vincent's Hospital, College of Medicine, The Catholic University of Korea, 93-6 Ji-dong Paldal-gu, Suwon, Kyeonggi-do, Republic of Korea.
Purpose:
Tomotherapy for intensity-modulated radiation has been demonstrated to reduce unnecessary irradiations to adjacent organs at risk (OARs). The purpose of this study was to compare the dosimetric parameters between Tomotherapy and three-dimensional conformal radiotherapy (3D-CRT) in rectal cancer patients.
Materials And Methods:
We redesigned three-dimensional conformal plans for 20 rectal cancer patients who had received short-course preoperative radiotherapy with Tomotherapy. The target coverage for 3D-CRT and Tomotherapy was evaluated with the following including the mean dose, V(nGy), D(min), D(max), radiation conformality index (RCI), and radical dose homogeneity index (rDHI).
Results:
The mean PTV dose for Tomotherapy is significantly higher than that observed for the 3D-CRT (p = 0.043). However, there is no significant difference in the V(23.25Gy), V(26.25Gy), V(27.5Gy), and RCI values between Tomotherapy and 3D-CRT. However, the average rDHI (p < 0.001) value for Tomotherapy was significantly lower than that reported for the 3D-CRT. Tomotherapy significantly lowered the mean level of irradiation doses to the bladder, small bowel, and femur heads as compared to 3D-CRT.
Conclusions:
Tomotherapy could produce a favorable target coverage and significant dose reduction for the OARs at the expense of acceptable dose inhomogeneity of the PTV compared with 3D-CRT in rectal cancer patients.
