A dosimetry method for low dose rate brachytherapy by EGS5 combined with regression to reflect source strength shortage

Tanaka, Kenichi; Tateoka, Kunihiko; Asanuma, Osamu; Kamo, Ken-ichi; Sato, Kaori; Takeda, Hiroyuki; Takagi, Masaru; Hareyama, Masato; Takada, Jun

doi:10.1093/jrr/rrt147

Cited by 2 publications

(3 citation statements)

References 12 publications

(1 reference statement)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A method for estimating the strength of a source while it is being implanted has been proposed as a backup for quality assurance [ 9 ]. The method for estimating the moving-source strength is briefly described here, and is described in detail in other publications [ 9 , 10 ]. Source strength measurement has been shown to be difficult during actual implantations because the speed of the source varies, as the source is moved manually.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Anin vitroverification of strength estimation for moving an 125I source during implantation in brachytherapy

Tanaka

Kajimoto

Hayashi

et al. 2018

Journal of Radiation Research

View full text Add to dashboard Cite

This study aims to demonstrate the feasibility of a method for estimating the strength of a moving brachytherapy source during implantation in a patient. Experiments were performed under the same conditions as in the actual treatment, except for one point that the source was not implanted into a patient. The brachytherapy source selected for this study was 125I with an air kerma strength of 0.332 U (μGym2h−1), and the detector used was a plastic scintillator with dimensions of 10 cm × 5 cm × 5 cm. A calibration factor to convert the counting rate of the detector to the source strength was measured and then the accuracy of the proposed method was investigated for a manually driven source. The accuracy was found to be under 10% when the shielding effect of additional needles for implantation at other positions was corrected, and about 30% when the shielding was not corrected. Even without shielding correction, the proposed method can detect dead/dropped source, implantation of a source with the wrong strength, and a mistake in the number of the sources implanted. Furthermore, when the correction was applied, the achieved accuracy came close to within 7% required to find the Oncoseed 6711 (125I seed with unintended strength among the commercially supplied values of 0.392, 0.462 and 0.533 U).

show abstract

Section: Introductionmentioning

confidence: 99%

“…The feasibility of the proposed method has been verified experimentally using a clinical source moving at different constant speeds for both a loose source [ 9 ] and linked sources [ 10 ]. In the present study, the validity of the proposed method was investigated for a source that was manually driven.…”

Section: Introductionmentioning

confidence: 99%

Anin vitroverification of strength estimation for moving an 125I source during implantation in brachytherapy

Tanaka

Kajimoto

Hayashi

et al. 2018

Journal of Radiation Research

View full text Add to dashboard Cite

show abstract

“…Some groups have estimated ISA to be up to 10% of the tumor dose [ 5 , 6 ]. As a possible option for improving dose calculations, we previously validated the use of Monte Carlo calculations and measurements with a radiophotoluminescent glass rod dosimeter for the 125 I source model Oncoseed 6711 [ 7 , 8 ]. Those studies were also conducted in order to accumulate estimates of the TG43U1 parameters and dosimetry data for geometry lacking the equilibrium radiation scatter conditions.…”

Section: Introductionmentioning

confidence: 99%

A comparison of the dose distributions between the brachytherapy 125I source models, STM1251 and Oncoseed 6711, in a geometry lacking radiation equilibrium scatter conditions

Tanaka

Kamo

Tateoka

et al. 2015

Journal of Radiation Research

View full text Add to dashboard Cite

The purpose of this study was to estimate the uncertainty in the dose distribution for the 125I source STM1251, as measured with a radiophotoluminescent glass rod dosimeter and calculated using the Monte Carlo code EGS5 in geometry that included the source structure reported by Kirov et al. This was performed at a range of positions in and on a water phantom 18 cm in diameter and 16 cm in length. Some dosimetry positions were so close to the surface that the backscatter margin was insufficient for photons. Consequently, the combined standard uncertainty (CSU) at the coverage factor k of 1 was 11.0–11.2% for the measurement and 1.8–3.6% for the calculation. The calculation successfully reproduced the measured dose distribution within 13%, with CSU at k ≤ 1.6 (P > 0.3). Dose distributions were then compared with those for the 125I source Oncoseed 6711. Our results supported the American Association of Physicists in Medicine Task Group No. 43 Updated Protocol (TG43U1) formalism, in which STM1251 dose distributions were more penetrating than those of Oncoseed 6711. This trend was also observed in the region near the phantom surface lacking the equilibrium radiation scatter conditions. In this region, the difference between the TG43U1 formalism and the measurement and calculation performed in the present study was not significant (P > 0.3) for either of the source models. Selection of the source model based on the treatment plans according to the TG43U1 formalism will be practical.

show abstract

A dosimetry method for low dose rate brachytherapy by EGS5 combined with regression to reflect source strength shortage

Cited by 2 publications

References 12 publications

Anin vitroverification of strength estimation for moving an 125I source during implantation in brachytherapy

Anin vitroverification of strength estimation for moving an 125I source during implantation in brachytherapy

A comparison of the dose distributions between the brachytherapy 125I source models, STM1251 and Oncoseed 6711, in a geometry lacking radiation equilibrium scatter conditions

Contact Info

Product

Resources

About