title: Small-Field Measurements of 3D Polymer Gel Dosimeters through Optical Computed Tomography.
abstract: With advances in therapeutic instruments and techniques, three-dimensional dose delivery has been widely used in radiotherapy. The verification of dose distribution in a small field becomes critical because of the obvious dose gradient within the field. The study investigates the dose distributions of various field sizes by using NIPAM polymer gel dosimeter. The dosimeter consists of 5% gelatin, 5% monomers, 3% cross linkers, and 5 mM THPC. After irradiation, a 24 to 96 hour delay was applied, and the gel dosimeters were read by a cone beam optical computed tomography (optical CT) scanner. The dose distributions measured by the NIPAM gel dosimeter were compared to the outputs of the treatment planning system using gamma evaluation. For the criteria of 3%/3 mm, the pass rates for 5 × 5, 3 × 3, 2 × 2, 1 × 1, and 0.5 × 0.5 cm2 were as high as 91.7%, 90.7%, 88.2%, 74.8%, and 37.3%, respectively. For the criteria of 5%/5 mm, the gamma pass rates of the 5 × 5, 3 × 3, and 2 × 2 cm2 fields were over 99%. The NIPAM gel dosimeter provides high chemical stability. With cone-beam optical CT readouts, the NIPAM polymer gel dosimeter has potential for clinical dose verification of small-field irradiation.
authors.affiliation: Graduate Institute of Clinical Medical Science, China Medical University, Taichung, Taiwan.|Department of Medical Imaging and Radiological Science, Central Taiwan University of Sciences and Technology, Taichung, Taiwan.|Department of Radiology, Cheng Ching Hospital at Chung Kang, Taichung, Taiwan.
authors.forename: Tian-Yu
authors.initials: TY
authors.lastname: Shih
authors.affiliation: Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Jay
authors.initials: J
authors.lastname: Wu
authors.affiliation: 3D Printing Medical Research Center, China Medical University Hospital, Taichung, Taiwan.
authors.forename: Cheng-Ting
authors.initials: CT
authors.lastname: Shih
authors.affiliation: Department of Medical Imaging and Radiological Science, Central Taiwan University of Sciences and Technology, Taichung, Taiwan.
authors.forename: Yao-Ting
authors.initials: YT
authors.lastname: Lee
authors.affiliation: Department of Radiology, Cheng Ching Hospital at Chung Kang, Taichung, Taiwan.
authors.forename: Shin-Hua
authors.initials: SH
authors.lastname: Wu
authors.affiliation: Graduate Institute of Clinical Medical Science, China Medical University, Taichung, Taiwan.|Department of Biomedical Imaging and Radiological Science, College of Health Care, China Medical University, Taichung, Taiwan.|Department of Biomedical Informatics, Asia University, Taichung, Taiwan.
authors.forename: Chun-Hsu
authors.initials: CH
authors.lastname: Yao
authors.affiliation: Department of Medical Imaging and Radiological Science, Central Taiwan University of Sciences and Technology, Taichung, Taiwan.
authors.forename: Bor-Tsung
authors.initials: BT
authors.lastname: Hsieh
mesh_terms: D000180:Acrylic Resins; D004307:Dose-Response Relationship, Radiation; D008027:Light; D011108:Polymers / Q000737:chemistry*; D011874:Radiometry / Q000379:methods*; D041622:Tomography, Optical / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D000180:Acrylic Resins; D011108:Polymers; C052970:poly-N-isopropylacrylamide