Scintillator screen for measuring dose distribution in scanned carbon-ion therapy

Yogo, Katsunori; Tatsuno, Yuya; Souda, Hikaru; Matsumura, Akihiko; Tsuneda, Masato; Hirano, Yoshiyuki; Ishiyama, Hiromichi; Saito, A.; Ozawa, Shogo; Nagata, Yasushi; Nakano, Takashi; Hayakawa, Kazushige; Kanai, Tatsuaki

doi:10.1016/j.radmeas.2019.106207

Cited by 7 publications

(16 citation statements)

References 33 publications

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“…Quenching occurs when many excitons are produced by high LET particles and results in the depletion of activator sites. These differences due to the quenching effect are similar to those reported in other studies on pencil beams [ 18 , 20 ], and they are much smaller than those of the Gd scintillator, which produced an underestimation at the Bragg peak of approximately 40% [ 14 , 20 ]. The differences between the scintillator and ion-chamber data for the SOBP beam are much smaller than those of the mono-energetic beam, which can be attributed to the smaller LET of the SOBP beams ( Figs 5 and 6 ).…”

Section: Discussionsupporting

confidence: 87%

“…The ZnS scintillator underestimates the SOBP center by approximately 10%, which is a significantly lower underestimation than that of the mono-energetic passive and pencil beams ( Fig. 6 ) [ 18 , 20 ].…”

Section: Resultsmentioning

confidence: 99%

“…We thus employed the ZnS scintillator, instead of the Gd-based scintillators used in previous studies on therapeutic ion beams [ 9–14 ]. We previously reported that the ZnS scintillator provided a lower LET dependence on carbon ions than Gd-based scintillators [ 20 ]. Thus, ZnS scintillators require much smaller corrections than Gd scintillators in estimating dose distributions based on brightness distributions for carbon-ion pencil beams [ 20 , 21 ].…”

Section: Discussionmentioning

confidence: 99%

“…In the depth profiles of the carbon-ion pencil beam, the scintillator intensities were previously slightly higher than those of the chamber in the rising region of the Bragg peak [ 20 ]. However, this tendency was not observed in the depth profiles measured in this study; note that we used the same scintillator and chamber used in Yogo et al.…”

Section: Discussionmentioning

confidence: 99%

“…A silver-activated zinc sulfide (ZnS) scintillator was selected for carbon-ion beam dosimetry with a higher LET [ 17–19 ]. In a previous study, we proposed a ZnS scintillator for measuring dose profiles in high- and low-dose regions of carbon-ion pencil beams [ 20 , 21 ]. This technique proved to be superior to methods employing a Gd-based scintillator in terms of LET.…”

Section: Introductionmentioning

confidence: 99%

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Three-dimensional dose-distribution measurement of therapeutic carbon-ion beams using a ZnS scintillator sheet

Yogo

Tsuneda

Horita

et al. 2021

Journal of Radiation Research

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The accurate measurement of the 3D dose distribution of carbon-ion beams is essential for safe carbon-ion therapy. Although ionization chambers scanned in a water tank or air are conventionally used for this purpose, these measurement methods are time-consuming. We thus developed a rapid 3D dose-measurement tool that employs a silver-activated zinc sulfide (ZnS) scintillator with lower linear energy transfer (LET) dependence than gadolinium-based (Gd) scintillators; this tool enables the measurement of carbon-ion beams with small corrections. A ZnS scintillator sheet was placed vertical to the beam axis and installed in a shaded box. Scintillation images produced by incident carbon-ions were reflected with a mirror and captured with a charge-coupled device (CCD) camera. A 290 MeV/nucleon mono-energetic beam and spread-out Bragg peak (SOBP) carbon-ion passive beams were delivered at the Gunma University Heavy Ion Medical Center. A water tank was installed above the scintillator with the water level remotely adjusted to the measurement depth. Images were recorded at various water depths and stacked in the depth direction to create 3D scintillation images. Depth and lateral profiles were analyzed from the images. The ZnS-scintillator-measured depth profile agreed with the depth dose measured using an ionization chamber, outperforming the conventional Gd-based scintillator. Measurements were realized with smaller corrections for a carbon-ion beam with a higher LET than a proton. Lateral profiles at the entrance and the Bragg peak depths could be measured with this tool. The proposed method would make it possible to rapidly perform 3D dose-distribution measurements of carbon-ion beams with smaller quenching corrections.

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