RT - Journal Article T1 - CT value organ and homogeneous assigned methods-based radiation treatment planning of pelvic cavity tumors JF - Int-J-Radiat-Res YR - 2019 JO - Int-J-Radiat-Res VO - 17 IS - 4 UR - http://ijrr.com/article-1-2695-en.html SP - 667 EP - 674 K1 - CT value interval K1 - organ assigned K1 - homogeneous assigned K1 - cervical carcinoma K1 - dose calculation K1 - TPS. AB - Objective: By dividing the CT value into different intervals, the authors aimed to investigate the effect of CT value variation on dosimetric results and propose a method to combine MRI with assigned CT values. Materials and Methods: Imaging data were analyzed from thirty patients in three different regions by a treatment planning system. The average CT value of each tissue or organ, standard deviation and 95% confidence interval were obtained by the Eclipse treatment planning system. Fifteen patients were included in this study by IMRT. Eclipse was used for all delineations, registrations, and dose calculations. In the synthetic CT image, the CT values of the target and OAR were assigned according to the sampled CT value above. The homogeneous assigned method divides the human tissue CT image into another synthetic CT image that only assigns bones and water. Dosimetric differences and dose homogeneity were compared under the same dose and field conditions. Results: By dividing the CT value with the interval method and verifying it with dose calculation, different CT value intervals can reflect different human tissues or organs. The effect of CT value variation between -100 HU and 100 HU on dose calculation is within 2%. Compared with the same treatment plan on different CT images, there is little deviation between the synthetic CT image and the original CT image. The Dmax, Dmean, Dmean, D98%, D95%, D5%, and D2% of PTV are all below 1.61%, and the dose percentage and volume percentage of OAR are below 1.86%. Conclusion: The combination of MRI with assigned CT values is feasible for the performance of MR alone in pelvis tumor treatment plans. LA eng UL http://ijrr.com/article-1-2695-en.html M3 ER -