Limits...
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

Radial dose functions calculated for the new 90Y source and the old 90Sr/90Y source. The line is the polynomial fit of order 5 for the new 90Y source
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4663217&req=5

Figure 0003: Radial dose functions calculated for the new 90Y source and the old 90Sr/90Y source. The line is the polynomial fit of order 5 for the new 90Y source

Mentions: In Figure 3, a fitted polynomial function of the new 90Y source and a comparison of the radial dose functions of the new 90Y and the old 90Sr/90Y source calculated according to EGS4 from Wang et al. [8], and the differences between two sources at right ordinate axis are presented. The comparison between two sources revealed the following: (a) at the radial distances of r ≤ 2.0 mm, our calculated gL(r) values agreed with the calculations of Wang et al.'s within 3.3%; (b) for 2.0 mm ≤ r ≤ 4.0 mm, differences between our calculations and those of Wang et al. were greater than 11%; and (c) for 4.0 mm ≤ r ≤ 8.0 mm, our calculations were greater than those of Wang et al. by up to 34%. These results confirm that the different active core and geometry of the source dose significantly affected the values of the radial dose functions. These differences were due to the average energies, sizes, and materials of the two sources (our new 90Y source had a greater energy than Wang et al.'s old 90Sr/90Y source according to their energy spectrum and the values of the reference absorbed dose rate; the length of the active core was 4.7 mm rather than 2.5 mm and the material of the capsule was PE, rather than stainless steel).


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)

Radial dose functions calculated for the new 90Y source and the old 90Sr/90Y source. The line is the polynomial fit of order 5 for the new 90Y source
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 0003: Radial dose functions calculated for the new 90Y source and the old 90Sr/90Y source. The line is the polynomial fit of order 5 for the new 90Y source
Mentions: In Figure 3, a fitted polynomial function of the new 90Y source and a comparison of the radial dose functions of the new 90Y and the old 90Sr/90Y source calculated according to EGS4 from Wang et al. [8], and the differences between two sources at right ordinate axis are presented. The comparison between two sources revealed the following: (a) at the radial distances of r ≤ 2.0 mm, our calculated gL(r) values agreed with the calculations of Wang et al.'s within 3.3%; (b) for 2.0 mm ≤ r ≤ 4.0 mm, differences between our calculations and those of Wang et al. were greater than 11%; and (c) for 4.0 mm ≤ r ≤ 8.0 mm, our calculations were greater than those of Wang et al. by up to 34%. These results confirm that the different active core and geometry of the source dose significantly affected the values of the radial dose functions. These differences were due to the average energies, sizes, and materials of the two sources (our new 90Y source had a greater energy than Wang et al.'s old 90Sr/90Y source according to their energy spectrum and the values of the reference absorbed dose rate; the length of the active core was 4.7 mm rather than 2.5 mm and the material of the capsule was PE, rather than stainless steel).

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