A Novel Thin NIPAM Gel Cassette Dosimeter for Photon-Beam Radiotherapy

Hsieh, Ling‐Ling; Cheng, Kai Yuan; Hsieh, Bor‐Tsung

doi:10.1371/journal.pone.0031836

Cited by 7 publications

(2 citation statements)

References 26 publications

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“…Since the prescribed dose in the center of the field was 5 Gy, the dose and dose rate near the edge may be lower than the applicable range of the NIPAM gel dosimeters. This phenomenon can also be observed in the percent depth dose (PDD) measurement using the NIPAM gel cassette [ 16 ], where the PDD of the gel dosimeter was significantly lower than the result of the ion chamber at the build-up region. Fortunately, the dose information in the penumbra region has a low effect on the treatment quality.…”

Section: Resultsmentioning

confidence: 90%

Small-Field Measurements of 3D Polymer Gel Dosimeters through Optical Computed Tomography

Shih

et al. 2016

PLoS ONE

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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.

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Section: Resultsmentioning

confidence: 90%

Small-Field Measurements of 3D Polymer Gel Dosimeters through Optical Computed Tomography

Shih

et al. 2016

PLoS ONE

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“…Polymer gel dosimetry (PGD) for complex radiation therapy dose verification has been under development for more than two decades and a thorough review is provided in Baldock et al (2010). The technique aims to utilize radiosensitive 3D polymer gel materials as, ultimately, anthropomorphic phantoms for dose verification of complex treatment, end-to-end dosimetry, or as an aid in new technique development (Johnston et al 2012, Yeo et al 2012, Pavoni et al 2012, Hsieh et al 2012, Wu et al 2011. Traditionally, dose information from irradiated PGDs has been extracted using magnetic resonance imaging (MRI) (e.g.…”

Section: Introductionmentioning

confidence: 99%

Dose calibration optimization and error propagation in polymer gel dosimetry

Jirásek

Hilts

2014

Phys. Med. Biol.

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This study reports on the relative precision, relative error, and dose differences observed when using a new full-image calibration technique in NIPAM-based x-ray CT polymer gel dosimetry. The effects of calibration parameters (e.g. gradient thresholding, dose bin size, calibration fit function, and spatial remeshing) on subsequent errors in calibrated gel images are reported. It is found that gradient thresholding, dose bin size, and fit function all play a primary role in affecting errors in calibrated images. Spatial remeshing induces minimal reductions or increases in errors in calibrated images. This study also reports on a full error propagation throughout the CT gel image pre-processing and calibration procedure thus giving, for the first time, a realistic view of the errors incurred in calibrated CT polymer gel dosimetry. While the work is based on CT polymer gel dosimetry, the formalism is valid for and easily extended to MRI or optical CT dosimetry protocols. Hence, the procedures developed within the work are generally applicable to calibration of polymer gel dosimeters.

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