SU‐FF‐T‐326: On the Use of Ice as a Water‐Equivalent Solid Medium for Brachytherapy Dosimetry Measurement

H. Song; Z. Chen; N. Yue; Q. J. wu; F. Yin

doi:10.1118/1.2760989

SU‐FF‐T‐326: On the Use of Ice as a Water‐Equivalent Solid Medium for Brachytherapy Dosimetry Measurement

H. Song, Z. Chen, N. Yue, Q. J. wu, F. Yin

Cancer Institute of New Jersey (CINJ), Radiation Oncology

Research output: Contribution to journal › Article › peer-review

Abstract

Purpose: It is well‐known that fluctuation in chemical compositions can lead to significant errors in the dosimetry of low‐energy brachytherapy sources using the traditional “water‐equivalent” solid phantoms. The aim of this work was to investigate the feasibility of using ice as a consistent water equivalent solid medium for low‐energy brachytherapy dosimetry. Methodod and Materials: The MCNP Monte Carlo code was used to compute the solid‐phantom‐to‐water conversion factor for ice (R_ice) and for SolidWater™ (R_SW) irradiated with mono‐energetic photons of 10 keV to 2.0 MeV and photons of six brachytherapy sources at various physical distances from the source. The R_SW for different chemical compositions observed in SolidWater™ was also calculated. The feasibility of making precise ice phantoms was explored theoretically from an engineering point of view. Results: The uncertainty associated with the chemical composition of the SolidWater™ phantom can cause large errors in R_SW for photons emitted by [formula omitted] source: 9% at 1 cm, 47% at 5 cm and 72% at 10 cm radial distance while ice would be free from such errors. However, due to its lower physical density compared to liquid water, the R_ice was found to depend on both the photon energy and distance from the source. At the distance of 1 cm used in reference dosimetry, R_ice varied from 0.890 at 15 keV to 1.015 at 50 keV. A practical approach for making ice slabs with pre‐designed molds of brachytherapy sources and dosimeters was proposed. Conclusions: A comprehensive set of R_ice has been calculated for mono‐energetic photons and for photons emitted by existing brachytherapy sources at various measurement depths. Using R_ice with an ice phantom would eliminate errors resulted from chemical composition fluctuations in traditional SolidWater™ phantom while retaining the positioning advantages of a solid phantom. Experimental measurements using ice phantom are being planned.

Original language	English (US)
Pages (from-to)	2476
Number of pages	1
Journal	Medical Physics
Volume	34
Issue number	6
DOIs	https://doi.org/10.1118/1.2760989
State	Published - Jun 2007

All Science Journal Classification (ASJC) codes

Biophysics
Radiology Nuclear Medicine and imaging

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10.1118/1.2760989

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@article{795093b7aa8c4fceafb80a8f48206046,

title = "SU‐FF‐T‐326: On the Use of Ice as a Water‐Equivalent Solid Medium for Brachytherapy Dosimetry Measurement",

abstract = "Purpose: It is well‐known that fluctuation in chemical compositions can lead to significant errors in the dosimetry of low‐energy brachytherapy sources using the traditional “water‐equivalent” solid phantoms. The aim of this work was to investigate the feasibility of using ice as a consistent water equivalent solid medium for low‐energy brachytherapy dosimetry. Methodod and Materials: The MCNP Monte Carlo code was used to compute the solid‐phantom‐to‐water conversion factor for ice (Rice) and for SolidWater{\texttrademark} (RSW) irradiated with mono‐energetic photons of 10 keV to 2.0 MeV and photons of six brachytherapy sources at various physical distances from the source. The RSW for different chemical compositions observed in SolidWater{\texttrademark} was also calculated. The feasibility of making precise ice phantoms was explored theoretically from an engineering point of view. Results: The uncertainty associated with the chemical composition of the SolidWater{\texttrademark} phantom can cause large errors in RSW for photons emitted by [formula omitted] source: 9% at 1 cm, 47% at 5 cm and 72% at 10 cm radial distance while ice would be free from such errors. However, due to its lower physical density compared to liquid water, the Rice was found to depend on both the photon energy and distance from the source. At the distance of 1 cm used in reference dosimetry, Rice varied from 0.890 at 15 keV to 1.015 at 50 keV. A practical approach for making ice slabs with pre‐designed molds of brachytherapy sources and dosimeters was proposed. Conclusions: A comprehensive set of Rice has been calculated for mono‐energetic photons and for photons emitted by existing brachytherapy sources at various measurement depths. Using Rice with an ice phantom would eliminate errors resulted from chemical composition fluctuations in traditional SolidWater{\texttrademark} phantom while retaining the positioning advantages of a solid phantom. Experimental measurements using ice phantom are being planned.",

author = "H. Song and Z. Chen and N. Yue and wu, {Q. J.} and F. Yin",

year = "2007",

month = jun,

doi = "10.1118/1.2760989",

language = "English (US)",

volume = "34",

pages = "2476",

journal = "Medical Physics",

issn = "0094-2405",

publisher = "John Wiley and Sons Ltd",

number = "6",

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T1 - SU‐FF‐T‐326

T2 - On the Use of Ice as a Water‐Equivalent Solid Medium for Brachytherapy Dosimetry Measurement

AU - Song, H.

AU - Chen, Z.

AU - Yue, N.

AU - wu, Q. J.

AU - Yin, F.

PY - 2007/6

Y1 - 2007/6

N2 - Purpose: It is well‐known that fluctuation in chemical compositions can lead to significant errors in the dosimetry of low‐energy brachytherapy sources using the traditional “water‐equivalent” solid phantoms. The aim of this work was to investigate the feasibility of using ice as a consistent water equivalent solid medium for low‐energy brachytherapy dosimetry. Methodod and Materials: The MCNP Monte Carlo code was used to compute the solid‐phantom‐to‐water conversion factor for ice (Rice) and for SolidWater™ (RSW) irradiated with mono‐energetic photons of 10 keV to 2.0 MeV and photons of six brachytherapy sources at various physical distances from the source. The RSW for different chemical compositions observed in SolidWater™ was also calculated. The feasibility of making precise ice phantoms was explored theoretically from an engineering point of view. Results: The uncertainty associated with the chemical composition of the SolidWater™ phantom can cause large errors in RSW for photons emitted by [formula omitted] source: 9% at 1 cm, 47% at 5 cm and 72% at 10 cm radial distance while ice would be free from such errors. However, due to its lower physical density compared to liquid water, the Rice was found to depend on both the photon energy and distance from the source. At the distance of 1 cm used in reference dosimetry, Rice varied from 0.890 at 15 keV to 1.015 at 50 keV. A practical approach for making ice slabs with pre‐designed molds of brachytherapy sources and dosimeters was proposed. Conclusions: A comprehensive set of Rice has been calculated for mono‐energetic photons and for photons emitted by existing brachytherapy sources at various measurement depths. Using Rice with an ice phantom would eliminate errors resulted from chemical composition fluctuations in traditional SolidWater™ phantom while retaining the positioning advantages of a solid phantom. Experimental measurements using ice phantom are being planned.

AB - Purpose: It is well‐known that fluctuation in chemical compositions can lead to significant errors in the dosimetry of low‐energy brachytherapy sources using the traditional “water‐equivalent” solid phantoms. The aim of this work was to investigate the feasibility of using ice as a consistent water equivalent solid medium for low‐energy brachytherapy dosimetry. Methodod and Materials: The MCNP Monte Carlo code was used to compute the solid‐phantom‐to‐water conversion factor for ice (Rice) and for SolidWater™ (RSW) irradiated with mono‐energetic photons of 10 keV to 2.0 MeV and photons of six brachytherapy sources at various physical distances from the source. The RSW for different chemical compositions observed in SolidWater™ was also calculated. The feasibility of making precise ice phantoms was explored theoretically from an engineering point of view. Results: The uncertainty associated with the chemical composition of the SolidWater™ phantom can cause large errors in RSW for photons emitted by [formula omitted] source: 9% at 1 cm, 47% at 5 cm and 72% at 10 cm radial distance while ice would be free from such errors. However, due to its lower physical density compared to liquid water, the Rice was found to depend on both the photon energy and distance from the source. At the distance of 1 cm used in reference dosimetry, Rice varied from 0.890 at 15 keV to 1.015 at 50 keV. A practical approach for making ice slabs with pre‐designed molds of brachytherapy sources and dosimeters was proposed. Conclusions: A comprehensive set of Rice has been calculated for mono‐energetic photons and for photons emitted by existing brachytherapy sources at various measurement depths. Using Rice with an ice phantom would eliminate errors resulted from chemical composition fluctuations in traditional SolidWater™ phantom while retaining the positioning advantages of a solid phantom. Experimental measurements using ice phantom are being planned.

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SU‐FF‐T‐326: On the Use of Ice as a Water‐Equivalent Solid Medium for Brachytherapy Dosimetry Measurement

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