Solid-state luminescence dosimeters face challenge in achieving accurate dosimetry in proton therapy owing to the linear energy transfer (LET)-dependent response. In this study, we proposed a two-dosimeter-based methodology to improve the accuracy of proton dosimetry by correcting the LET-dependent response of a radiophotoluminescence glass dosimeter (RPLD) and an Al2O3:Cr-based ceramic-type thermoluminescence dosimeter (TLD) for postal dosimetry. The LET dependent response for the RPLD and Al2O3:Cr TLD was investigated using an unmodulated 235 MeV proton beam delivered by a passive scattering system. Both dosimeters were individually calibrated in terms of the absorbed dose to water using a 6 MV X-ray beam. The luminescence efficiency ratio between the RPLD and Al2O3:Cr TLD (<InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="12194_2025_942_Article_IEq1.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="97" /> </InlineMediaObject> <EquationSource Format="TEX">${\eta }_{{\text{RPLD}, \, \text{Al}}_{2}{\text{O}}_{3}:\text{Cr}}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>η</mi> <mrow> <msub> <mrow> <mtext>RPLD</mtext> <mo>,</mo> <mspace width="0.166667em" /> <mtext>Al</mtext> </mrow> <mn>2</mn> </msub> <msub> <mtext>O</mtext> <mn>3</mn> </msub> <mo>:</mo> <mtext>Cr</mtext> </mrow> </msub> </math></EquationSource> </InlineEquation>) was used as an index to determine the LET dependence correction factor for the RPLD and Al2O3:Cr TLD (<InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="12194_2025_942_Article_IEq2.gif" Format="GIF" Height="21" Rendition="HTML" Resolution="72" Type="Linedraw" Width="44" /> </InlineMediaObject> <EquationSource Format="TEX">${k}_{\text{LET}}^{\text{RPLD}}$</EquationSource> <EquationSource Format="MATHML"><math> <msubsup> <mi>k</mi> <mrow> <mtext>LET</mtext> </mrow> <mtext>RPLD</mtext> </msubsup> </math></EquationSource> </InlineEquation> and <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="12194_2025_942_Article_IEq3.gif" Format="GIF" Height="23" Rendition="HTML" Resolution="72" Type="Linedraw" Width="59" /> </InlineMediaObject> <EquationSource Format="TEX">${k}_{\text{LET}}^{{\text{Al}}_{2}{\text{O}}_{3}:\text{Cr}}$</EquationSource> <EquationSource Format="MATHML"><math> <msubsup> <mi>k</mi> <mrow> <mtext>LET</mtext> </mrow> <mrow> <msub> <mtext>Al</mtext> <mn>2</mn> </msub> <msub> <mtext>O</mtext> <mn>3</mn> </msub> <mo>:</mo> <mtext>Cr</mtext> </mrow> </msubsup> </math></EquationSource> </InlineEquation>). Modulated proton beams with different spread-out Bragg peak (SOBP) widths were used to evaluate the feasibility of the proposed two-dosimeter methodology. <InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="12194_2025_942_Article_IEq1.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="97" /> </InlineMediaObject> <EquationSource Format="TEX">${\eta }_{{\text{RPLD}, \, \text{Al}}_{2}{\text{O}}_{3}:\text{Cr}}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>η</mi> <mrow> <msub> <mrow> <mtext>RPLD</mtext> <mo>,</mo> <mspace width="0.166667em" /> <mtext>Al</mtext> </mrow> <mn>2</mn> </msub> <msub> <mtext>O</mtext> <mn>3</mn> </msub> <mo>:</mo> <mtext>Cr</mtext> </mrow> </msub> </math></EquationSource> </InlineEquation> decreased with increasing LET. <InlineEquation ID="IEq5"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="12194_2025_942_Article_IEq2.gif" Format="GIF" Height="21" Rendition="HTML" Resolution="72" Type="Linedraw" Width="44" /> </InlineMediaObject> <EquationSource Format="TEX">${k}_{\text{LET}}^{\text{RPLD}}$</EquationSource> <EquationSource Format="MATHML"><math> <msubsup> <mi>k</mi> <mrow> <mtext>LET</mtext> </mrow> <mtext>RPLD</mtext> </msubsup> </math></EquationSource> </InlineEquation> and <InlineEquation ID="IEq6"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="12194_2025_942_Article_IEq3.gif" Format="GIF" Height="23" Rendition="HTML" Resolution="72" Type="Linedraw" Width="59" /> </InlineMediaObject> <EquationSource Format="TEX">${k}_{\text{LET}}^{{\text{Al}}_{2}{\text{O}}_{3}:\text{Cr}}$</EquationSource> <EquationSource Format="MATHML"><math> <msubsup> <mi>k</mi> <mrow> <mtext>LET</mtext> </mrow> <mrow> <msub> <mtext>Al</mtext> <mn>2</mn> </msub> <msub> <mtext>O</mtext> <mn>3</mn> </msub> <mo>:</mo> <mtext>Cr</mtext> </mrow> </msubsup> </math></EquationSource> </InlineEquation> were fitted using exponential curves. Proton dosimetry based on the proposed methodology underestimated the absorbed dose to water by an averages of 1.88% and 3.21% for RPLD and Al2O3:Cr TLD, respectively. This demonstrated the feasibility of the proposed methodology. Although the method shows promise for LET correction, the uncertainties in the LET-dependent correction factors, namely 2.39% for the RPLD and 5.84% for the Al₂O₃:Cr TLD, indicate the need for further refinement.

Linear energy transfer correction using Al₂O₃:Cr thermoluminescent and radiophotoluminescence glass dosimeters for therapeutic proton dosimetry

期刊论文
出版模式：

开放获取
发表日期：

2025年7月18日

查看全文

Weishan Chang,
Hina Suzuki,
Kenji Hotta,
Puspen Chakraborty,
Yusuke Koba,
Nozomi Ohba,
Kiyomitsu Shinsho

摘要

Solid-state luminescence dosimeters face challenge in achieving accurate dosimetry in proton therapy owing to the linear energy transfer (LET)-dependent response. In this study, we proposed a two-dosimeter-based methodology to improve the accuracy of proton dosimetry by correcting the LET-dependent response of a radiophotoluminescence glass dosimeter (RPLD) and an Al₂O₃:Cr-based ceramic-type thermoluminescence dosimeter (TLD) for postal dosimetry. The LET dependent response for the RPLD and Al₂O₃:Cr TLD was investigated using an unmodulated 235 MeV proton beam delivered by a passive scattering system. Both dosimeters were individually calibrated in terms of the absorbed dose to water using a 6 MV X-ray beam. The luminescence efficiency ratio between the RPLD and Al₂O₃:Cr TLD ( ${\eta }_{{\text{RPLD}, \, \text{Al}}_{2}{\text{O}}_{3}:\text{Cr}}$ $η_{{RPLD, Al}_{2} O_{3} : Cr}$ ) was used as an index to determine the LET dependence correction factor for the RPLD and Al₂O₃:Cr TLD ( ${k}_{\text{LET}}^{\text{RPLD}}$ $k_{LET}^{RPLD}$ and ${k}_{\text{LET}}^{{\text{Al}}_{2}{\text{O}}_{3}:\text{Cr}}$ $k_{LET}^{{Al}_{2} O_{3} : Cr}$ ). Modulated proton beams with different spread-out Bragg peak (SOBP) widths were used to evaluate the feasibility of the proposed two-dosimeter methodology. ${\eta }_{{\text{RPLD}, \, \text{Al}}_{2}{\text{O}}_{3}:\text{Cr}}$ $η_{{RPLD, Al}_{2} O_{3} : Cr}$ decreased with increasing LET. ${k}_{\text{LET}}^{\text{RPLD}}$ $k_{LET}^{RPLD}$ and ${k}_{\text{LET}}^{{\text{Al}}_{2}{\text{O}}_{3}:\text{Cr}}$ $k_{LET}^{{Al}_{2} O_{3} : Cr}$ were fitted using exponential curves. Proton dosimetry based on the proposed methodology underestimated the absorbed dose to water by an averages of 1.88% and 3.21% for RPLD and Al₂O₃:Cr TLD, respectively. This demonstrated the feasibility of the proposed methodology. Although the method shows promise for LET correction, the uncertainties in the LET-dependent correction factors, namely 2.39% for the RPLD and 5.84% for the Al₂O₃:Cr TLD, indicate the need for further refinement.