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TH‐CD‐209‐03: Feasibility of CBCT‐Based Proton Dose Calculation Using a Histogram‐Matching Algorithm in Proton Beam Therapy
Author(s) -
Arai K,
Kadoya N,
Kato T,
Endo H,
Komori S,
Abe Y,
Hirose K,
Nakamura T,
Wada H,
Kikuchi Y,
Jingu K
Publication year - 2016
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.4958197
Subject(s) - hounsfield scale , dose volume histogram , nuclear medicine , proton therapy , cone beam computed tomography , imaging phantom , radiation treatment planning , medicine , radiation therapy , cone beam ct , image registration , dosimetry , histogram , head and neck , computed tomography , radiology , computer science , artificial intelligence , image (mathematics) , surgery
Purpose: The aim of this study was to confirm On‐Board Imager cone‐beam computed tomography (CBCT) using a histogram‐matching algorithm as a useful method for proton dose calculation in head and neck radiotherapy. Methods: We studied one head and neck phantom and ten patients with head and neck cancer treated using intensity‐modulated radiation therapy (IMRT) and proton beam therapy. We modified Hounsfield unit (HU) values of CBCT (mCBCT) using a histogram‐matching algorithm. In order to evaluate the accuracy of the proton dose calculation, we compared dose differences in dosimetric parameters (Dmean) for clinical target volume (CTV), planning target volume (PTV) and left parotid and proton ranges (PR) between the planning CT (reference) and CBCT or mCBCT, and gamma passing rates of CBCT and mCBCT. To minimize the effect of organ deformation, we also performed image registration. Results: For patients, the average differences in Dmean for CTV, PTV, and left parotid between planning CT and CBCT were 1.63 ± 2.34%, 3.30 ± 1.02%, and 5.42 ± 3.06%, respectively. Similarly, the average differences between planning CT and mCBCT were 0.20 ± 0.19%, 0.58 ±0.43%, and 3.53 ±2.40%, respectively. The average differences in PR between planning CT and CBCT or mCBCT of a 50° beam for ten patients were 2.1 ± 2.1 mm and 0.3 ± 0.5 mm, respectively. Similarly, the average differences in PR of a 120° beam were 2.9 ± 2.6 mm and 1.1 ± 0.9 mm, respectively. The average dose and PR differences of mCBCT were smaller than those of CBCT. Additionally, the average gamma passing rates of mCBCT were larger than those of CBCT. Conclusion: We evaluated the accuracy of the proton dose calculation in CBCT and mCBCT with the image registration for ten patients. Our results showed that HU modification using a histogram‐matching algorithm could improve the accuracy of the proton dose calculation.