Ex) Article Title, Author, Keywords
Ex) Article Title, Author, Keywords
Korean Journal of Medical Physics 2010; 21(4): 332-339
Published online December 25, 2010
Copyright © Korean Society of Medical Physics.
Kwang-Ho Cheong, Soah Park, Sei-Kwon Kang, Tae-Jin Hwang, Me Yeon Lee, Kyoung-Joo Kim, Hoonsik Bae, Do-Hoon Oh
정광호ㆍ박소아ㆍ강세권ㆍ황태진ㆍ이미연ㆍ김경주ㆍ배훈식ㆍ오도훈
We aimed to setup an adaptive radiation therapy platform using cone-beam CT (CBCT) and multileaf collimator (MLC) log data and also intended to analyze a trend of dose calculation errors during the procedure based on a phantom study. We took CT and CBCT images of Catphan-600 (The Phantom Laboratory, USA) phantom, and made a simple step-and-shoot intensity-modulated radiation therapy (IMRT) plan based on the CT. Original plan doses were recalculated based on the CT (CTplan) and the CBCT (CBCTplan). Delivered monitor unit weights and leaves-positions during beam delivery for each MLC segment were extracted from the MLC log data then we reconstructed delivered doses based on the CT (CTrecon) and CBCT (CBCTrecon) respectively using the extracted information. Dose calculation errors were evaluated by two-dimensional dose discrepancies (CTplan was the benchmark), gamma index and dose-volume histograms (DVHs). From the dose differences and DVHs, it was estimated that the delivered dose was slightly greater than the planned dose; however, it was insignificant. Gamma index result showed that dose calculation error on CBCT using planned or reconstructed data were relatively greater than CT based calculation. In addition, there were significant discrepancies on the edge of each beam while those were less than errors due to inconsistency of CT and CBCT. CBCTrecon showed coupled effects of above two kinds of errors; however, total error was decreased even though overall uncertainty for the evaluation of delivered dose on the CBCT was increased. Therefore, it is necessary to evaluate dose calculation errors separately as a setup error, dose calculation error due to CBCT image quality and reconstructed dose error which is actually what we want to know.
KeywordsAdaptive radiation therapy, Cone-beam CT, MLC log data, IMRT
pISSN 2508-4445
eISSN 2508-4453
Formerly ISSN 1226-5829
Frequency: Quarterly