Thermoluminescence Properties for X-ray of Cr-doped Al2O3 Ceramics - Research Findings

Aug 25, 2026

Investigations focus on the fundamental thermoluminescence (TL) characteristics of Cr-doped low-melting-point Al2O3 intended for X-ray dosimetry and two-dimensional (2D) radiotherapy verification. Cr2O3 concentrations from 0.01 to 1.0 wt% were evaluated, with 0.05 wt% providing the best performance. Doping stabilizes trapped states, markedly improving fading, and boosts X-ray sensitivity to about 4.8 times that of non-doped Al2O3. Cr-doped samples demonstrate high TL sensitivity, reproducibility, radiation resistance, and thermal stability, and enable 2D plan verification matching RT plans.

LanguageEnglish

CategoryResearch & Report

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Introduction

Materials and Methods

Materials and glow curve measurement system

(Further sections beyond provided excerpt)

Sensors and Materials, Vol. 30, No. 7 (2018) 1591–1598 1591 MYU Tokyo S & M 1615 Thermoluminescence Properties for X-ray of Cr-doped Al2O3 Ceramics Kiyomitsu Shinsho,1* Daiki Maruyama,1 Shin Yanagisawa,1 Yusuke Koba,2 Mizuki Kakuta,1 Kazuki Matsumoto,3 Hiroaki Ushiba,3 and Takayuki Andoh4 1Tokyo Metropolitan University, 7-2-10 Higashi-Oku, Arakawa-ku, Tokyo 116-8551, Japan 2QST NIRS, 4-9-1 Anagawa, Inage-ku, Chiba-shi, Chiba 263-8555, Japan 3Chiyoda Technol Corporation, 1-7-12 Yushima, Bunkyo-ku, Tokyo 113-8681, Japan 4Chibaceramic MFG Co. Ltd., 2-10-14 Inage-higashi, Inage-ku, Chiba-shi, Chiba 263-0031, Japan (Received January 28, 2018; accepted May 25, 2018) Keywords: thermoluminescent phosphor, Al2O3, glow curve, two-dimensional dosimeter We investigated the basic thermoluminescence (TL) characteristics of Cr-doped low-meltingpoint Al2O3. The concentration of Cr2O3 in this study ranged from 0.01 to 1.0 wt% . Owing to the stabilization of the trapped state caused by Cr doping, we successfully improved the lowmelting-point Al2O3 fading property dramatically. Then, the sensitivity of 0.05 wt% Cr-doped Al2O3 to X-rays was about 4.8 times higher than that of the nondoped Al2O3, allowing the Al2O3 to maintain its attractive properties to X-rays. Furthermore, the 0.05 wt% Cr-doped Al2O3 had good properties for dosimetry owing to its high TL sensitivity, high reproducibility, high radiation resistivity, and high thermal stability in two dimensions. Finally, we demonstrated two-dimensional (2D) verifications of radiotherapy (RT) plans using Cr-doped Al2O3 ceramic plates. The results had good agreement with RT plans. 1. Introduction Modern radiotherapy (RT) can focus radiation into a tumor with high precision, which leads to better therapeutic gains over other methods. Therefore, both the irradiation field and the dosage require highly precise validation. Currently, a radiochromic film is typically used for the two-dimensional (2D) verification of RT plans. It has good tissue equivalence and a high spatial resolution. However, the technique has some limitations, including high material costs in certain countries and a narrow dynamic range, among others. There are some alternatives to the use of the radiochromic film. The thermoluminescence dosimeter (TLD) is one of the alternatives. Recently, with the advent of the CCD camera, the high-resolution imaging of large areas has become much faster, so the amount of research on X-ray imaging using 2D-TLD was increased.(1–6) In particular, human-tissue-equivalent 2D-TLD has been paid more attention owing to focusing needs in the medical field. However, it has low reproducibility, low signal-to-noise ratio, and low solidity; thus, there is no suitable human-tissue-equivalent 2D-TLD. * Corresponding author: e-mail: [shinsho@tmu.ac.jp](shinsho@tmu.ac.jp) This was published on July 27, 2018, and errors detected after publication were corrected on August 3, 2018. [http://dx.doi.org/10.18494/SAM.2018.1928](http://dx.doi.org/10.18494/SAM.2018.1928) ISSN 0914-4935 © MYU K.K. [http://myukk.org/](http://myukk.org/) 1592 Sensors and Materials, Vol. 30, No. 7 (2018) High-purity Al2O3 has been reported to maintain high sensitivity, but it is not a suitable material for 2D-TLD owing to its high melting point of 2,072 ℃.(7) Thus, the costs of both the material and its production have become high. We focused on a thermoluminescence (TL) phosphor Al2O3 with a low melting point of approximately 1600 ℃ with some sintering assistance. It is easy to produce a large plate using Al2O3, owing to the low costs of the materials and production system, compared with that in the case of the high-purity Al2O3. We reported that a commercially available Al2O3 plate with a low melting point of 1600 ℃ has a low material cost and a wide dynamic range, and is reusable.(8) However, it is necessary to improve this material’s fading property, owing to an unstable trap state at a glow peak tempe

FAQs

What was the goal of doping Al2O3 with chromium in this study?

To investigate and improve the thermoluminescence properties of low-melting-point Al2O3, especially fading behavior and performance for X-ray dosimetry and 2D radiotherapy verification.

How did Cr doping affect TL fading and X-ray sensitivity?

Cr doping stabilizes trapped states, dramatically improving the fading property. The 0.05 wt% Cr-doped Al2O3 shows about 4.8 times higher X-ray sensitivity than non-doped Al2O3.

How were two-dimensional radiotherapy plan verifications performed?

Cr-doped Al2O3 ceramic plates were used for 2D verification of radiotherapy plans, and the measured results agreed well with the RT plans.

Aug 25, 2026

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