Image reconstruction of optical computed tomography by using the algebraic reconstruction technique for dose readouts of polymer gel dosimeters. Issue 8 (December 2015)

• Record Type: Journal Article
• Authors: Shih, Cheng-Ting; Chang, Yuan-Jen; Hsu, Jui-Ting; Chuang, Keh-Shih; Chang, Shu-Jun; Wu, Jay
• Is Part Of: Physica medica. Volume 31:Issue 8(2015)
• Page Start: 942
• Page End: 947
• Publication Date: 2015-12
• Subjects: Optical computed tomography -- Algebraic reconstruction technique -- Polymer gel dosimeter; Medical physics -- Periodicals; Biophysics -- Periodicals; Biophysics -- Periodicals; Imagerie médicale -- Périodiques; Radiothérapie -- Périodiques; Rayons X -- Sécurité -- Mesures -- Périodiques; Physique -- Périodiques; Médecine -- Périodiques; 610.153
• DOI: 10.1016/j.ejmp.2015.06.013
• Languages: English
• ISSNs: 1120-1797

Abstract

Abstract: Optical computed tomography (optical CT) has been proven to be a useful tool for dose readouts of polymer gel dosimeters. In this study, the algebraic reconstruction technique (ART) for image reconstruction of gel dosimeters was used to improve the image quality of optical CT. Cylindrical phantoms filled with N -isopropyl-acrylamide polymer gels were irradiated using a medical linear accelerator. A circular dose distribution and a hexagonal dose distribution were produced by applying the VMAT technique and the six-field dose delivery, respectively. The phantoms were scanned using optical CT, and the images were reconstructed using the filtered back-projection (FBP) algorithm and the ART. For the circular dose distribution, the ART successfully reduced the ring artifacts and noise in the reconstructed image. For the hexagonal dose distribution, the ART reduced the hot spots at the entrances of the beams and increased the dose uniformity in the central region. Within 50% isodose line, the gamma pass rates for the 2 mm/3% criteria for the ART and FBP were 99.2% and 88.1%, respectively. The ART could be used for the reconstruction of optical CT images to improve image quality and provide accurate dose conversion for polymer gel dosimeters. Highlights: ART was used to reconstruct the OCT images of polymer gels. Image quality and accuracy of dose readout were evaluated. Difference of fidelity was used as the stopping criterion for ART. Dose maps of ART have higher gamma pass rate than those of FBP.