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Monte Carlo dosimetry of a new (90)Y brachytherapy source.

Junxiang W, Shihu Y, Jing H, Fengxiang L, Chengkai W, Zhangwen W, Qing H, Chengjun G - J Contemp Brachytherapy (2015)

Bottom Line: The active core length of the new (90)Y source was increased to 4.7 mm compared to the value of 2.5 mm for the old (90)Sr/(90)Y source.The reference absorbed dose rate for the new (90)Y source was determined to be equal to 1.6608 ± 0.0008 cGy s(-1) mCi(-1), compared to the values of 0.9063 ± 0.0005 cGy s(-1) mCi(-1) that were calculated for the old (90)Sr/(90)Y source.These data are meant to be used commercially in after-loading system.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Radiation Physics and Technology, Ministry of Education and Institute of Nuclear Science and Technology, Sichuan University.

ABSTRACT

Purpose: In this study, we attempted to obtain full dosimetric data for a new (90)Y brachytherapy source developed by the College of Chemistry (Sichuan University) for use in high-dose-rate after-loading systems.

Material and methods: The dosimetric data for this new source were used as required by the dose calculation formalisms proposed by the AAPM Task Group 60 and Task Group 149. The active core length of the new (90)Y source was increased to 4.7 mm compared to the value of 2.5 mm for the old (90)Sr/(90)Y source. The Monte Carlo simulation toolkit Geant4 was used to calculate these parameters. The source was located in a 30-cm-radius theoretical sphere water phantom.

Results: The dosimetric data included the reference absorbed dose rate, the radial dose function in the range of 1.0 to 8.0 mm in the longitudinal axis, and the anisotropy function with a θ in the range of 0° to 90° at 5° intervals and an r in the range of 1.0 to 8.0 mm in 0.2-mm intervals. The reference absorbed dose rate for the new (90)Y source was determined to be equal to 1.6608 ± 0.0008 cGy s(-1) mCi(-1), compared to the values of 0.9063 ± 0.0005 cGy s(-1) mCi(-1) that were calculated for the old (90)Sr/(90)Y source. A polynomial function was also obtained for the radial dose function by curve fitting.

Conclusions: Dosimetric data are provided for the new (90)Y brachytherapy source. These data are meant to be used commercially in after-loading system.

No MeSH data available.


Related in: MedlinePlus

Polar coordinate system for the dose calculation
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Figure 0002: Polar coordinate system for the dose calculation

Mentions: The dose calculation formalism for the beta-emitting source proposed by the AAPM report TG60 in 1999 was followed. This formalism is described in terms of the polar coordinate system as shown in Figure 2. For a beta-particle-emitting source, the dose calculation formalism is different from that for a photon-emitting source. The air kerma strength (Sk) and dose rate constant in water (Λ) were replaced by the reference absorbed dose rate D(r0, θ0), which has units of cGy s–1 mCi–1. This replacement occurred because the air kerma was only applied to photon emitting sources and did not exist for beta-emitting sources [5]. The dose at any point around the source can be expressed as follows:1D(r,θ)=D(r0,θ0)×GL(r,θ)GL(r0,θ0)×gL(r)×F(r,θ)


Monte Carlo dosimetry of a new (90)Y brachytherapy source.

Junxiang W, Shihu Y, Jing H, Fengxiang L, Chengkai W, Zhangwen W, Qing H, Chengjun G - J Contemp Brachytherapy (2015)

Polar coordinate system for the dose calculation
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4663217&req=5

Figure 0002: Polar coordinate system for the dose calculation
Mentions: The dose calculation formalism for the beta-emitting source proposed by the AAPM report TG60 in 1999 was followed. This formalism is described in terms of the polar coordinate system as shown in Figure 2. For a beta-particle-emitting source, the dose calculation formalism is different from that for a photon-emitting source. The air kerma strength (Sk) and dose rate constant in water (Λ) were replaced by the reference absorbed dose rate D(r0, θ0), which has units of cGy s–1 mCi–1. This replacement occurred because the air kerma was only applied to photon emitting sources and did not exist for beta-emitting sources [5]. The dose at any point around the source can be expressed as follows:1D(r,θ)=D(r0,θ0)×GL(r,θ)GL(r0,θ0)×gL(r)×F(r,θ)

Bottom Line: The active core length of the new (90)Y source was increased to 4.7 mm compared to the value of 2.5 mm for the old (90)Sr/(90)Y source.The reference absorbed dose rate for the new (90)Y source was determined to be equal to 1.6608 ± 0.0008 cGy s(-1) mCi(-1), compared to the values of 0.9063 ± 0.0005 cGy s(-1) mCi(-1) that were calculated for the old (90)Sr/(90)Y source.These data are meant to be used commercially in after-loading system.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Radiation Physics and Technology, Ministry of Education and Institute of Nuclear Science and Technology, Sichuan University.

ABSTRACT

Purpose: In this study, we attempted to obtain full dosimetric data for a new (90)Y brachytherapy source developed by the College of Chemistry (Sichuan University) for use in high-dose-rate after-loading systems.

Material and methods: The dosimetric data for this new source were used as required by the dose calculation formalisms proposed by the AAPM Task Group 60 and Task Group 149. The active core length of the new (90)Y source was increased to 4.7 mm compared to the value of 2.5 mm for the old (90)Sr/(90)Y source. The Monte Carlo simulation toolkit Geant4 was used to calculate these parameters. The source was located in a 30-cm-radius theoretical sphere water phantom.

Results: The dosimetric data included the reference absorbed dose rate, the radial dose function in the range of 1.0 to 8.0 mm in the longitudinal axis, and the anisotropy function with a θ in the range of 0° to 90° at 5° intervals and an r in the range of 1.0 to 8.0 mm in 0.2-mm intervals. The reference absorbed dose rate for the new (90)Y source was determined to be equal to 1.6608 ± 0.0008 cGy s(-1) mCi(-1), compared to the values of 0.9063 ± 0.0005 cGy s(-1) mCi(-1) that were calculated for the old (90)Sr/(90)Y source. A polynomial function was also obtained for the radial dose function by curve fitting.

Conclusions: Dosimetric data are provided for the new (90)Y brachytherapy source. These data are meant to be used commercially in after-loading system.

No MeSH data available.


Related in: MedlinePlus