pmp Progress in Medical Physics Progress in Medical Physics 2508-4445 2508-4453 Korean Society of Medical Physics 10.14316/pmp.2017.28.1.16 pmp-28-16 Original Article Evaluation of Dual-channel Compound Method for EBT3 Film Dosimetry KangSang-Won ∗ ChungJin-Beom † KimKyeong-Hyeon ∗ EomKeun-Yong † SongChanghoon † LeeJeong-Woo ‡ ChoWoong § SuhTae Suk ∗ Research Institute of Biomedical Engineering, College of Medicine, The Catholic University of Korea, Seoul, Korea Department of Radiation Oncology, Seoul National University Bundang Hospital, Seongnam, Korea Department of Radiation Oncology, Kunkuk University Medical Center, Seoul, Korea Department of Radiation Oncology, Seoul Metropolitan Government Seoul National University Boramae Medical Center, Seoul, Korea Corresponding author Tae Suk Suh (suhsanta@catholic.ac.kr) Tel: 82-2-2258-7501 Fax: 82-2-2258-7506 Co-corresponding author Jin-Beom Chung (jbchung1213@gmail.com) Tel: 82-31-787-7654 Fax: 82-31-787-4019 32017 1732017 281 1621 17032017 27032017 27032017 Copyright © 2017 Korean Society of Medical Physics 2017 This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract

This study assessed the feasibility of a dual-channel (DC) compound method for film dosimetry. The red channel (RC) is usually used to ensure dosimetric quality using a conventional fraction dose because the RC is more accurate at low doses within 3 Gy than is the green channel (GC). However, the RC is prone to rapid degradation of sensitivity at high doses, while degradation of the GC is slow. In this study, the DC compound method combining the RC and GC was explored as a means of providing accurate film dosimetry for high doses. The DC compound method was evaluated at various dose distributions using EBT3 film inserted in a solid-water phantom. Measurements with 10×20 cm2 radiation field and 60° dynamic-wedge were done. Dose distributions acquired using the RC and GC were analyzed with root-mean-squares-error (RMSE) and gamma analyses. The DC compound method was used based on the RC after correcting the GC for high doses in the gamma analysis. The RC and GC produced comparatively more accurate RMSE values for low and high doses, respectively. Gamma passing rates with an acceptance criterion of 3%/3 mm revealed that the RC provided rapid reduction in the high dose region, while the GC displayed a gradual decrease. In the whole dose range, the DC compound method had the highest agreement (93%) compared with single channel method using either the RC (80%) or GC (85%). The findings indicate that the use of DC compound method is more appropriate in dosimetric quality assurance for radiotherapy using high doses.

 Gafchromic EBT3 film Film dosimetry Dual-channel compound Gamma analysis REFERENCES James MG Greg B Quality assurance procedures for stereotactic body radiation therapy Int J Radiat Oncol Biol Phys. 200871 S1225 Eric EK Joseph H John B Fang-Fang Y William S Sean D TG Report 142: Quality assurance of medical accelerators. American Association of Physicists in Medicine Med Phys. 200936 4197212 Huq MS Fraass BA Dunscombe PB Gibbons JP Ibbott GS Medin PM A method for evaluating quality assurance needs in radiation therapy Int J Radiat Oncol Biol Phys. 200871 S1703 Chung JB Kang SW Eom KY Song C Choi KS Suh TS Comparison of dosimetric performance among commercial quality assurance systems for verifying pretreatment plans of stereotactic body radiotherapy using flattening-filter-free beams J Korean Med Sci. 201631 17428 Hayashi N Watanabe Y Malmin R Kato H Evaluation of triple channel correction acquisition method for radiochromic film dosimetry J Radiat Res. 201253 9305 Reinhardt S Hillbrand M Wilkens JJ Assmann W Comparison of gafchromic EBT2 and EBT3 films for clinical photon and proton beams Med Phys. 201239 525762 Devic S Seuntjens J Sham E Podgorsak EB Schmidtlein CR Kirov AS Precise radiochromic film dosimetry using a flatbed document scanner Med Phys. 200532 224553 Ferreira BC Lopes MC Capela M Evaluation of an Epson flatbed scanner to read gafchromic EBT films for radiation dosimetry Phys Med Biol. 200954 107385 Fukumoto S Shirato H Shimzu S Ogura S Onimaru R Kitamura K Small-volume image-guided radiotherapy using hypofractionated, coplanar, and noncoplanar multiple fields for patients with inoperable Stage I nonsmall cell lung carcinomas Cancer. 200295 154653 Gerszten PC Burton SA Welch WC Brufsky AM Lembersky BC Ozhasoglu C Single-fraction radiosurgery for the treatment of spinal breast metastases Cancer. 2005104 224454 Hara R Itami J Kondo T Aruga T Abe Y Ito M Stereotactic single high dose irradiation of lung tumors under respiratory gating Radiother Oncol. 200263 15963 Herfarth KK Debus J Lohr F Bahner ML Rhein B Fritz P Stereotactic single-dose radiation therapy of liver tumors: results of a phase I/II trial J Clin Oncol. 200119 16470 Borca VC Pasquino M Russo G Grosso P Cante D Sciacero P Dosimetric characterization and use of GAFCHROMIC EBT3 film for IMRT dose verification J Appl Clinic Med Phys. 201314 15871 Lewis D Micke A Yu X Chan MF An efficient protocol for radiochromic film dosimetry combining calibration and measurement in a single scan Med Phys. 201239 633950 Almond PR Biggs PJ Coursey BM Hanson WF Huq MS Nath R AAPM's TG-51 protocol for clinical reference dosimetry of high-energy photon and electron beams Med Phys. 199926 184770 Devic S Radiochromic film dosimetry: Past, present, and future Phys Med. 201127 12234 Moran JM Radawski J Fraass BA A dose-gradient analysis tool for IMRT QA J Appl Clinic Med Phys. 20056 6273 Ju T Simpson T Deasy JO Low DA Geometric interpretation of the g dose distribution comparison technique: Interpolation-free calculation Med Phys. 200835 87987 Figures and Tables

Calibration net optical-density (netOD) curves for the red and green channel.

EBT film showing a mimic image irradiated radiation for analyzing cross- (red dot line) and in-line (blue dot line) profiles.

The dose profiles ((a) cross-line and (b) in-line) obtained in DRC and DGC compared to DCalc. The cross-line profile was measured in central-axis for dose distribution and the in-line profiles were measured in five positions of d1, d2, d3, d4, and d5, respectively.

Gamma distributions of analysis for (a) red, (b) green channel, (c) dual-channel compound method, and (d) the converted gamma distribution of green channel.

Comparison of the gamma passing rates in dose distributions using the red channel, green channel, and dual-channel compound method with increasing doses.

Root-mean-squares-error (RMSE) value for dose profiles in DRC∗ and DGC∗ compared to DCalc∗.

    RMSE between DRC and DCalc RMSE between DGC and DCalc
Cross-line Central axis 50.63 27.38
In-line d1∗ 8.47 2.88
  d2∗ 6.31 8.38
  d3∗ 16.86 22.13
  d4∗ 21.15 31.44
  d5∗ 115.95 38.14

d1, d2, d3, d4 and d5: five positions of −8, −4, 0, 4, and 9 cm from the normalization point, respectively.

DRC, DGC, and DCalc: the dose distribution obtained by using red and green channel and calculated dose distribution.