Liver segment-based assessment of dosimetric characteristics of helical tomotherapy for portal vein tumor thrombus under different jaw modes(PDF)
《中国医学物理学杂志》[ISSN:1005-202X/CN:44-1351/R]
- Issue:
- 2020年第7期
- Page:
- 803-809
- Research Field:
- 医学放射物理
- Publishing date:
Info
- Title:
- Liver segment-based assessment of dosimetric characteristics of helical tomotherapy for portal vein tumor thrombus under different jaw modes
- Author(s):
- XIE Chuanbin; XU Shouping; DAI Xiangkun; CHEN Gaoxiang; GE Ruigang; GONG Hanshun; QU Baolin
- Department of Radiation Oncology, the First Medical Center of Chinese PLA General Hospital, Beijing 100853, China
- Keywords:
- Keywords: helical tomotherapy jaw mode portal vein tumor thrombus liver segment dosimetric characteristic
- PACS:
- R735.7；R811.1
- DOI:
- DOI:10.3969/j.issn.1005-202X.2020.07.002
- Abstract:
- Abstract: Objective To explore the dosimetric characteristics of helical tomotherapy for portal vein tumor thrombus under different jaw modes by liver segment-based assessment. Methods Twelve patients with portal vein tumor thrombus were enrolled in the study. According to the anatomical relationship between the target area and the liver, the liver was divided into 3 parts, namely Lsup which was defined by the part beyond the superior edge of the target area, Linf which was defined by the part beyond the inferior edge of the target area, and Lmid which was defined by the middle part. Three groups of fixed jaw (FJ) plans with the field width (FW) of 1.0, 2.5 and 5.0 cm, respectively, were designed and defined as F1.0, F2.5 and F5.0 and two groups of dynamic jaw (DJ) plans with FW of 2.5 and 5.0 cm were designed and defined as D2.5 and D5.0. The dosimetric differences of the target area and organs-at-risk were analyzed and compared among different groups, and the delivery efficiency was also evaluated. Results The dose distributions in the target area were similar in 5 groups. With the same FW, DJ plans reduced the irradiation dose of the whole liver significantly and obtained the result that was close to that of FJ plans with smaller FW. When FW were 2.5 and 5.0 cm, the mean dose of Lsup in DJ plans was decreased by 35.5% and 51.3% as compared with that of FJ plans, but the mean dose of Lmid varied slightly. The irradiation dose of Lsup increased obviously with the increase of FW under each jaw mode, while the irradiation dose of Lmid showed a trend of slight increase, and there were no statistical significance. The delivery time was increased significantly with the increase of FW. With the same FW, the gantry periods and delivery time of DJ plans were increased. Conclusion DJ technique can be used to not only effectively reduce the dose extension along the longitudinal edge of the target area due to the increase of FW, thereby increasing the corresponding dose gradient, but also significantly decrease the irradiation doses of normal tissues and organs-at-risk such as liver.
Last Update: 2020-07-28