Radiological characteristics of MRI-based VIP polymer gel under carbon beam irradiation

Maeyama, Takashige; Fukunishi, Nobuhisa; Ishikawa, Kenichi L.; Furuta, Takuya; Fukasaku, Kazuaki; Takagi, Shigeru; Noda, Shinichi; Himeno, R.; Fukuda, Satoshi

doi:10.1016/j.radphyschem.2014.09.001

Cited by 22 publications

(12 citation statements)

References 30 publications

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“…The IC dose was measured at each PMMA thickness in terms of the water equivalent thickness. The dose near the Bragg peak was determined with the smallest interval using a 500 μm PMMA plate . The irradiation experiment using deaerated NC-FG was performed twice on February 26, 2015 and June 9, 2015 to verify the reproducibility of the measurements for gels prepared on different days.…”

Section: Methodsmentioning

confidence: 99%

“…A 3D chemical dosimeter using a gel matrix has been proposed by Gore, in which the amount of radiation-induced chemical reaction products stored in the gel matrix provides information on the spatial dose distribution. The 3D dose distribution can be extracted from measurements of irradiated gel samples using a 3D imaging technique such as magnetic resonance imaging (MRI). , On the other hand, the practical application of a gel dosimeter to heavy ion beam dosimetry is complicated by the degradation in sensitivity as a function of linear energy transfer (LET). − This LET dependence of the radiation sensitivity is well-known as LET effects that are caused by radical–radical recombinations of radical products (i.e., OH, e aq – , and H) that contribute to radiation-induced chemical reactions . A Fricke gel dosimeter prepared using an aqueous Fricke solution and a gel matrix such as gelatin or agarose also shows LET dependence .…”

Section: Introductionmentioning

confidence: 99%

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Organic-Gelatin-Free Nanocomposite Fricke Gel Dosimeter

et al. 2017

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We report a nanocomposite Fricke gel (NC-FG) dosimeter prepared using only Fe and nanoclay in water, without any organic gelling agents. This dosimeter gels due to its thixotropic properties and exhibits linear energy transfer (LET)-independent radiological properties under carbon ion beam irradiation. The radiation sensitivity of this dosimeter was 1.8 [s kGy], which is three times higher than that reported previously (0.6 [s kGy]) for a similar dosimeter containing gelatin. The Fe yield was determined to be 0.19 μmol/J by evaluating the difference in spin-lattice relaxivity between Fe and Fe. A further increase in the radiation sensitivity was observed upon addition of the hydrated electron scavenger NO, suggesting the reduction of Fe by a hydrated electron. LET-dependent variations of the contributions of OH radicals and hydrated electrons compensate each other in the oxidation yield of NC-FG. This is the main mechanism of the suppression of LET effects in the Bragg peak compared to conventional Fricke dosimeters. The radiation-induced oxidation yield G(Fe) can be described by the stoichiometric equation {G(Fe) = G(OH) - G(e) + 2G(HO) + G(H)} with the reported LET dependence of the primary yield of water decomposition radicals. The calculated results are in approximate agreement with the absolute value of the experimental oxidation yield of NC-FG. The effects of the addition of small amounts of radical scavengers (nitrate, selenate, or cadmium) are also evaluated. The sensitivity was divided into two types, and influences of intermediate radicals after scavenging reaction are indicated.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Organic-Gelatin-Free Nanocomposite Fricke Gel Dosimeter

et al. 2017

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“…Three-dimensional (3D) dosimetry of heavy ion beam irradiation is required in particle therapy using carbon ion beam. On the other hand, the practical application of a solid-state or gel-state dosimeter to heavy ion beam 3D dosimetry is complicated by the degradation in sensitivity as a function of linear energy transfer (LET) [1][2][3]. Although Fricke gel [4][5][6][7][8] dosimeter also shows LET dependent dose responses [9,10], the Fricke gel prepared with nano-clay under deaerated conditions (NC-FG: nanocomposite Fricke gel) shows LET-independent dose responses, and this is the only 3D dosimeter for heavy ion beam [10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Effects of radical scavengers on nanocomposite Fricke gel for heavy ion beam irradiation

Maeyama

Fukunishi

Ishikawa

et al. 2022

J. Phys.: Conf. Ser.

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“…Several researchers have reported on the use of polymer gel dosimeters for carbon beam dosimetry [ 28 , 29 , 30 , 31 ]. However, polymer gel dosimeters are also LET-dependent, and thus, it is challenging to measure the dose distribution of carbon ion beams.…”

Section: Introductionmentioning

confidence: 99%

“…However, polymer gel dosimeters are also LET-dependent, and thus, it is challenging to measure the dose distribution of carbon ion beams. While LET-dependent correction methods using dose-weighted sensitivity, calculated from Monte Carlo simulations, have been proposed [ 31 ], complex dose calibration is required. Maeyama et al [ 32 ], developed a novel nanocomposite Fricke gel (NC-FG) with nano-sized clay particles and degassing operation to improve LET dependence.…”

Section: Introductionmentioning

confidence: 99%

Whole Three-Dimensional Dosimetry of Carbon Ion Beams with an MRI-Based Nanocomposite Fricke Gel Dosimeter Using Rapid T1 Mapping Method

Mizukami

Watanabe

Mizoguchi

et al. 2021

Gels

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MRI-based gel dosimeters are attractive systems for the evaluation of complex dose distributions in radiotherapy. In particular, the nanocomposite Fricke gel dosimeter is one among a few dosimeters capable of accurately evaluating the dose distribution of heavy ion beams. In contrast, reduction of the scanning time is a challenging issue for the acquisition of three-dimensional volume data. In this study, we investigated a three-dimensional dose distribution measurement method for heavy ion beams using variable flip angle (VFA), which is expected to significantly reduce the MRI scanning time. Our findings clarified that the whole three-dimensional dose distribution could be evaluated within the conventional imaging time (20 min) and quality of one cross-section.

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Radiological characteristics of MRI-based VIP polymer gel under carbon beam irradiation

Cited by 22 publications

References 30 publications

Organic-Gelatin-Free Nanocomposite Fricke Gel Dosimeter

Organic-Gelatin-Free Nanocomposite Fricke Gel Dosimeter

Effects of radical scavengers on nanocomposite Fricke gel for heavy ion beam irradiation

Whole Three-Dimensional Dosimetry of Carbon Ion Beams with an MRI-Based Nanocomposite Fricke Gel Dosimeter Using Rapid T1 Mapping Method

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