Patient organ doses from kV-cone beam CT in image-guided radiation therapy and optimization of image dose and quality.

2014 Fiscal Year Final Research Report

• Project/Area Number: 24591843
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Radiation science
• Research Institution: Kumamoto University
• Principal Investigator: ARAKI Fujio 熊本大学, 生命科学研究部, 教授 (00295148)
• Co-Investigator(Renkei-kenkyūsha): OHYA Natsuo 熊本大学, 大学院生命科学研究部, 教授 (70281095)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: Cone beam CT / IGRT / Monte Carlo simulation / CT dosimetry / 被ばく線量

Outline of Final Research Achievements

(1) We developed a novel method to directly evaluate the absorbed dose-to-water for kV-CBCT by Farmer ionization chamber measurements with a 60Co absorbed dose-to-water calibration factor. The absorbed doses for two kV-CBCT systems of the Varian On-Board Imager and the Elekta X-ray Volumetric Imager that currently are in widespread clinical use were measured by using the CT cylindrical water phantom. In addition, the dose distributions in the phantom for both kV-CBCT systems were calculated with Monte Carlo (MC) method and were compared with measured values.
(2) The patient dose distributions from kV-CBCT systems were computed from MC simulations by using patient CT image data sets for five treatment sites of head, “head and neck”, chest, abdomen, and pelvis. The organ doses at each site were quantitatively evaluated from dose-volume histograms. This approach made it possible to compare patient organ doses between two different kV-CBCT systems by using the same patient CT images.

Free Research Field

放射線治療計測学