Water equivalence of NIPAM based polymer gel dosimeters with enhanced sensitivity for x-ray CT

Gorjiara, Tina; Hill, Robin; Bosi, S.; Kuncic, Zdenka; Baldock, Clive

doi:10.1016/j.radphyschem.2013.05.018

Cited by 12 publications

(6 citation statements)

References 79 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Dose rate dependence is also examined. Tissue equivalence was confirmed by a separate group using Monte Carlo (MC) modelling studies (Gorjiara et al 2012). Temperature dependencies are not investigated explicitly as gel temperature was carefully controlled during irradiation and imaging, and recent work suggests radiation induced increases in the temperature of high concentration NIPAM gels do not affect their dose response (Sedaghat et al 2011).…”

Section: Introductionmentioning

confidence: 99%

An x-ray CT polymer gel dosimetry prototype: II. Gel characterization and clinical application

Johnston¹,

Hilts²,

Carrick³

et al. 2012

Phys. Med. Biol.

View full text Add to dashboard Cite

This article reports on the dosimetric properties of a new N-isopropylacrylamide, high %T, polymer gel formulation (19.5%T, 23%C), optimized for x-ray computed tomography (CT) polymer gel dosimetry (PGD). In addition, a new gel calibration technique is introduced together with an intensity-modulated radiation therapy (IMRT) treatment validation as an example of a clinical application of the new gel dosimeter. The dosimetric properties investigated include the temporal stability, spatial stability, batch reproducibility and dose rate dependence. The polymerization reaction is found to stabilize after 15 h post-irradiation. Spatial stability investigations reveal a small overshoot in response for gels imaged later than 36 h post-irradiation. Based on these findings, it is recommended that the new gel formulation be imaged between 15-36 h after irradiation. Intra- and inter-batch reproducibility are found to be excellent over the entire range of doses studied (0-28 Gy). A significant dose rate dependence is found for gels irradiated between 100-600 MU min⁻¹. Overall, the new gel is shown to have promising characteristics for CT PGD, however the implication of the observed dose rate dependence for some clinical applications remains to be determined. The new gel calibration method, based on pixel-by-pixel matching of dose and measured CT numbers, is found to be robust and to agree with the previously used region of interest technique. Pixel-by-pixel calibration is the new recommended standard for CT PGD. The dose resolution for the system was excellent, ranging from 0.2-0.5 Gy for doses between 0-20 Gy and 0.3-0.6 Gy for doses beyond 20 Gy. Comparison of the IMRT irradiation with planned doses yields excellent results: gamma pass rate (3%, 3 mm) of 99.3% at the isocentre slice and 93.4% over the entire treated volume.

show abstract

Section: Introductionmentioning

confidence: 99%

An x-ray CT polymer gel dosimetry prototype: II. Gel characterization and clinical application

Johnston¹,

Hilts²,

Carrick³

et al. 2012

Phys. Med. Biol.

View full text Add to dashboard Cite

show abstract

“…17 Recent research has moved toward preliminary clinical applications. 10,11 PGD has natural advantages as a dosimetric tool as polymer gels are inherently 3D, tissue equivalent 18 , and deformable. There has also been a significant amount of research into using less toxic, N-isopropyl-acrylamide (NIPAM)-based gel formulations to further increase clinical appeal.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of accuracy and precision in polymer gel dosimetry

et al. 2017

View full text Add to dashboard Cite

show abstract

“…This is possible due to chemical changes that occur after irradiation, where free radicals formed from water molecules initiate a gelation process [2]. The coexistence of monovinyl-and divinyl-monomers capable of polymerizing produces threedimensional networks (gels) which retain their initial spatial distribution for long periods thanks to the presence of a gelatin matrix [3].…”

Section: Introductionmentioning

confidence: 99%

Analytical and rheological studies of modified gel dosimeters exposed to X-ray beams

Romero

Mattea

Vedelago

et al. 2016

Microchemical Journal

View full text Add to dashboard Cite

The need to know the dose of X-rays to be applied to patients suffering diseases such as cancer requires accurate and stable dosimetric devices. Currently, the use of gelatin-based dosimeters has yielded excellent results but lack adequate thermal stability. In this paper a chemical modification of the gelatin (at concentrations typically used for the preparation of dosimeters) using glutaraldehyde as a cross-linking agent is proposed. Through rheological studies it was found that modified gelatin with glutaraldehyde concentrations between 0.15 and 0.50 % w / v show better thermal stability with an increase in elastic modulus of up to 100 times at 37°C and convenient reaction times for the preparation of the dosimeters. Subsequently, a mathematical model to easily predict the elastic modulus of materials prepared with different concentrations of gelatin and glutaraldehyde was proposed. The analytical response of modified and unmodified materials was evaluated and no significant alteration of the dosimetric sensitivity was found in the dosimeters (based on itaconic acid and N, N'-methylenebisacrylamide) when an X-ray irradiation dose from 0 to 300 Gy was applied. It was found that the best thermal A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT2 stability of dosimeters prepared with modified gelatin would decrease the loss of information between the irradiation process and the absorbance reading, thereby improving the stability and linear correlation of data.Overall, the results indicated that the dosimeters could be modified as proposed and achieve significant improvements regarding to their thermal stability, without changing significantly the usual preparation process.

show abstract

Water equivalence of NIPAM based polymer gel dosimeters with enhanced sensitivity for x-ray CT

Cited by 12 publications

References 79 publications

An x-ray CT polymer gel dosimetry prototype: II. Gel characterization and clinical application

An x-ray CT polymer gel dosimetry prototype: II. Gel characterization and clinical application

Evaluation of accuracy and precision in polymer gel dosimetry

Analytical and rheological studies of modified gel dosimeters exposed to X-ray beams

Contact Info

Product

Resources

About