Dosimetry of interstitial brachytherapy sources: Recommendations of the AAPM Radiation Therapy Committee Task Group No. 43

Monte Carlo calculations and TLD measurements have been performed for the purpose of characterizing dosimetric properties of new commercially available brachytherapy sources. All sources tested consisted of a solid core, upon which a thin layer of normalI125 has been adsorbed, encased within a titanium housing. The PharmaSeed BT‐125 source manufactured by Syncor is available in silver or palladium core configurations while the ADVANTAGE source from IsoAid has silver only. Dosimetric properties, including the dose rate constant, radial dose function, and anisotropy characteristics were determined according to the TG‐43 protocol. Additionally, the geometry function was calculated exactly using Monte Carlo and compared with both the point and line source approximations. The 1999 NIST standard was followed in determining air kerma strength. Dose rate constants were calculated to be 0.955±0.005,0.967±0.005, and 0.962±0.005 cGynormalh−1normalU−1 for the PharmaSeed BT‐125‐1, BT‐125‐2, and ADVANTAGE sources, respectively. TLD measurements were in excellent agreement with Monte Carlo calculations. Radial dose function, g(r), calculated to a distance of 10 cm, and anisotropy function F(r, θ), calculated for radii from 0.5 to 7.0 cm, were similar among all source configurations. Anisotropy constants, trueϕ¯an, were calculated to be 0.941, 0.944, and 0.960 for the three sources, respectively. All dosimetric parameters were found to be in close agreement with previously published data for similar source configurations. The MCNP Monte Carlo code appears to be ideally suited to low energy dosimetry applications.PACS number(s): 87.53.–j

Section: Introductionmentioning

confidence: 99%

{}^{60}{normalC} o

and

{}^{125}{normalI}

spectra is well established 20 .…”

Section: Introductionmentioning

confidence: 99%

Dosimetric parameters of three new solid core I‐125 brachytherapy sources

Solberg

DeMarco

Hugo

et al. 2002

“…Characteristics of the Model IR‐Seed2 source were determined according to the recommendations of the Task Group 43 (TG‐43U1) by the American Association of Physicists in Medicine (AAPM) 3 , 4 . Following this protocol, the spatial dose rate distribution

\dot{normalD} (r, θ)

around a sealed brachytherapy source can be determined using the following formula:

\overset{D}{true} false(r, θ false) = Λ S_{K} \frac{G false(r, θ false)}{G false(1 c m, \frac{true}{π} false)} g_{L} false(r false) F false(r, θ false),

…”

Section: Methodsmentioning

confidence: 99%

“…The experimental procedures were performed by using TLD chips in Plexiglas phantoms. The results of these investigations were compared with the published data of other commercially available

{}^{125}I

sources 4 , 5 …”

Section: Introductionmentioning

confidence: 99%

Monte Carlo calculations and experimental measurements of the TG‐43U1‐recommended dosimetric parameters of ¹²⁵I (Model IR‐Seed2) brachytherapy source

Sheikholeslami

Nedaie

Sadeghi³

et al. 2016

Self Cite

A new design of I125 (Model IR‐Seed2) brachytherapy source has been manufactured recently at the Applied Radiation Research School, Nuclear Science and Technology Research Institute in Iran. The source consists of six resin beads (0.5 mm diameter) that are sealed in a cylindrical titanium capsule of 0.7 mm internal and 0.8 mm external diameters. This work aims to evaluate the dosimetric parameters of the newly designed I125 source using experimental measurements and Monte Carlo (MC) simulations. Dosimetric characteristics (dose rate constant, radial dose function, and 2D and 1D anisotropy functions) of the IR‐Seed2 were determined using experimental measurements and MC simulations following the recommendations by the Task Group 43 (TG‐43U1) report of the American Association of Physicists in Medicine (AAPM). MC simulations were performed using the MCNP5 code in water and Plexiglas, and experimental measurements were carried out using thermoluminescent dosimeters (TLD‐GR207A) in Plexiglas phantoms. The measured dose to water in Plexiglas data were used for verification of the accuracy of the source and phantom geometry in the Monte Carlo simulations. The final MC simulated data to water in water were recommended for clinical applications. The MC calculated dose rate constant (Λ) of the IR‐Seed2 I125 seed in water was found to be 0.992±0.025 cGy normalh−1normalU−1. Additionally, its radial dose function by line and point source approximations, gLfalse(normalrfalse) and gpfalse(normalrfalse), calculated for distances from 0.1 cm to 7 cm. The values of gLfalse(rfalse) at radial distances from 0.5 cm to 5 cm were measured in a Plexiglas phantom to be between 1.212 and 0.413. The calculated and measured of values for 2D anisotropy function, F(r,θ), were obtained for the radial distances ranging from 1.5 cm to 5 cm and angular range of 0°‐90° in a Plexiglas phantom. Also, the 2D anisotropy function was calculated in water for the clinical application. The results of these investigations show that the uncertainty of the experimental data is within ±7% between the measured and simulated data in Plexiglas. Based on these results, the MC‐simulated dosimetric parameters of the new I125 source model in water are presented for its clinical applications in brachytherapy treatments.PACS number(s): 87.56.bg

“…Two of the cases were then reloaded using live seeds and the sleeved system. The source strength for each implant was chosen to match the anisotropically corrected dose rate of 0.4092 cGy/hr at 1 cm from the source using the point source approximation formalism 5 . The average number of sources and needles for these cases, by type, is given in Table I.…”

Section: Methodsmentioning

confidence: 99%

A comparative evaluation of loading times and exposures for permanent prostate brachytherapy

Bice

Walker²,

Gearty³

et al. 2002

The loading of needles for loose seed implantation of the prostate gland results requires a significant amount of effort and some radiation exposure to members of the medical staff. This study was performed to quantify the time spent and exposure levels associated with implant preparation, as well as to investigate any improvement in the time or exposure burden due to the introduction of a new loading device. The movements and radiation exposures for two single, highly experienced dosimetrists were monitored for ten conventionally loaded iodine implant cases. These same cases were reloaded with dummy sources using the sleeved system to determine time savings, if any. Two of these ten cases were then loaded with live sources using the sleeved system to determine relative exposure to the loading staff between the two methods. The results were then analyzed to generate per‐seed and per‐needle loading time and exposure burdens. Formulas are presented that may be used to determine the average time to load implants and the resultant staff exposure, both with the conventional technique and with the sleeved method. On the average, it takes an experienced loader 48 min to prepare an implant for the operating room, receiving a hand dose of about 10 mrem and a whole body dose of about 1 mrem. The sleeved system reduced these values by at least half. The time and exposure burden associated with the preparation of iodine loose seed implants has been characterized. The use of the sleeved needles resulted in significant time and exposure reductions for the medical staff.PACS number(s): 87.53Jw, 87.53.Xd