Effect of position repeatability on the verification of absolute dose for CyberKnife(PDF)
《中国医学物理学杂志》[ISSN:1005-202X/CN:44-1351/R]
- Issue:
- 2020年第9期
- Page:
- 1107-1110
- Research Field:
- 医学人工智能
- Publishing date:
Info
- Title:
- Effect of position repeatability on the verification of absolute dose for CyberKnife
- Author(s):
- WANG Lin
- Department of Radiation Oncology, Fujian Medical University Union Hospital, Fuzhou 350001, China
- Keywords:
- CyberKnife verification of phantom absolute dose position repeatability radiation beams
- PACS:
- R815
- DOI:
- 10.3969/j.issn.1005-202X.2020.09.005
- Abstract:
- Objective To measure the absolute dose delivered to phantom on newly introduced CyberKnife according to IAEATRS-
398 report for exploring the effect of the position repeatability of water phantom on the passing rate of absolute dose verification,
thereby ensuring that the prescription dose is accurately delivered to the tumors. Methods Three types of collimators (60, 40 and
25 mm) were used to design 3 different plans based on different incident directions of the beams which included normal incidence,
lateral incidence and mixed incidence. The absolute dose was measured by UNIDOSwebline electrometer from PTW, Germany, and
TW31010 0.125cc finger ionization chamber. Results Trivial dose deviations (less than 0.7%) were observed between the absolute
dose calculated by treatment planning system and measured results for 3 types of collimators in each group of experiments. The
verification deviation was about 2%, when the radiation beams entered the phantom at a normal incidence regardless of single
beams or multi beams.With some radiation beams entering the phantom at a lateral incidence, the deviation was gradually increased
from 3%to 4%.When all beams entered the phantom at a lateral incidence, the deviation was up to 5%. However, after the phantom
was fixed, the deviation was reduced to about 2% even there were radiation beams at a lateral incidence. Conclusion The main
reason for the increasing deviation between the results calculated by treatment planning system and the results measured by
electrometer is the repeatability of the relative position of phantom.
Last Update: 2020-09-25