Technical note: Monte‐Carlo dosimetry of the HDR 12i and Plus  sources

High‐dose‐rate (HDR) brachytherapy is a popular modality for treating cancers of the prostate, cervix, endometrium, breast, skin, bronchus, esophagus, and head and neck as well as soft‐tissue sarcomas. Because of different source designs and licensing issues, there is a need for specific dosimetry dataset for each HDR source model. The main objective of the present work is to measure 2D relative dose distribution around a new prototype 192Ir source, referred to as IRAsource‐HDR, in PMMA phantom in the framework of AAPM TG‐43 and TG‐55 recommendations for radial distances of 0.5 cm to 4 cm. Radiochromic films (RCFs) Gafchromic EBT and HD‐810 were used for measurements. The dose rate constant, Λ, of the source was determined to be 1.084±4.6%,1.129±4.4%, and 1.112±0.8% cGyh−1normalU−1 using EBTRCF, HD‐810 RCF, and Monte Carlo (MC) simulation, respectively. The results obtained in this study are in good agreement with previously published data for HDR interstitial 192Ir‐HDR sources with a maximum discrepancy of ±4.5%. An acceptable agreement (within ±2%) between MC calculations and RCFs measurements showed that HD‐810 RCF dosimetry is as good as EBTRCF, within HDR brachytherapy, and justifies the use of specific data for this new source. These data could be used as a benchmark for dose calculations in the conventional brachytherapy treatment planning systems.PACS number(s): 87.56.bg

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“…In Fig. 7 the calculated 2D anisotropy function was compared with the reference data 13 , 14 , 15 , 16 …”

Section: Resultsmentioning

confidence: 99%

“…Difference between IRAsource model and other similar

^{192} Ir

‐HDR sources in common use 13 , 14 , 15 , 16 , 17 is listed in Table 1. All HDR sources have similar active length and active core diameter and are all encapsulated in stainless steel tubes.…”

Section: Methodsmentioning

confidence: 99%

Gafchromic film dosimetry of a new HDR brachytherapy source

Ayoobian

Asl

Poorbaygi³

et al. 2016

J Applied Clin Med Phys

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“…31 Experimental phantoms are usually cubic and commonly used TPSs use as references a water cylinder of diameter and height 40 cm ͑Varian for the GammaMed Plus and 12i sources [20][21][22] ͒ or a water sphere of diameter 30 cm ͑Nucletron for all their sources 17,32-34 ͒. Results…”

Section: Discussionmentioning

confidence: 99%

Influence of phantom material and dimensions on experimental dosimetry

Tedgren

Carlsson

2009

Medical Physics

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In treatment planning of brachytherapy, absorbed dose is calculated by superposing predetermined distributions of absorbed dose to water in water for the single source according to the irradiation pattern ͓i.e., placement of the source͑s͒ or dwelling position͑s͔͒. Single-source reference water data are derived from Monte Carlo ͑MC͒ simulations and/or experiments. For reasons of positional accuracy, experimental brachytherapy dosimetry is most often performed in plastic phantoms. This work investigates the water equivalence of phantoms made from polystyrene, PMMA, and solid water for 192 Ir dosimetry. The EGSnrc MC code is used to simulate radial absorbed dose distributions in cylindrical phantoms of dimensions ranging in size from diameter and height of 20 cm to diameter and height of 40 cm. Water equivalence prevails if the absorbed dose to water in the plastic phantom is the same as the absorbed dose to water in a water phantom at equal distances from the source. It is shown that water equivalence at a specified distance from the source depends not only on the size of the plastic phantom but also on the size of the water phantom used for comparison. Compared to equally sized water phantoms, phantoms of polystyrene are less water equivalent than phantoms of PMMA and solid water but compared to larger water phantoms they are the most water equivalent. Although phantom dimension is the most important single factor influencing the dose distributions around 192 Ir sources, the effect of material properties is nonnegligible and becomes increasingly important as phantom dimensions increase. The importance of knowing the size of the water phantom whose data underlies treatment planning systems, when using such data as a reference in, e.g., detector evaluation studies, is discussed. To achieve the highest possible accuracy in experimental dosimetry, phantom-specific correction factors should be used.

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“…Monte Carlo dosimetry studies have been done (Angelopoulos et al 2000;Ballester et al 1997;Ballester et al 2001) for Ir-192 HDR brachytherapy sources. We modeled the Ir-192 HDR source (Fig.…”

Section: Radiation Sourcementioning

confidence: 99%

Quantifying tumor-selective radiation dose enhancements using gold nanoparticles: a monte carlo simulation study

Zhang

Gao

Buchholz

et al. 2009

Biomed Microdevices

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Gold nanoparticles can enhance the biological effective dose of radiation delivered to tumors, but few data exist to quantify this effect. The purpose of this project was to build a Monte Carlo simulation model to study the degree of dose enhancement achievable with gold nanoparticles. A Monte Carlo simulation model was first built using Geant4 code. An Ir-192 brachytherapy source in a water phantom was simulated and the calculation model was first validated against previously published data. We then introduced up to 10(13) gold nanospheres per cm(3) into the water phantom and examined their dose enhancement effect. We compared this enhancement against a gold-water mixture model that has been previously used to attempt to quantify nanoparticle dose enhancement. In our benchmark test, dose-rate constant, radial dose function, and two-dimensional anisotropy function calculated with our model were within 2% of those reported previously. Using our simulation model we found that the radiation dose was enhanced up to 60% with 10(13) gold nanospheres per cm(3) (9.6% by weight) in a water phantom selectively around the nanospheres. The comparison study indicated that our model more accurately calculated the dose enhancement effect and that previous methodologies overestimated the dose enhancement up to 16%. Monte Carlo calculations demonstrate that biologically-relevant radiation dose enhancement can be achieved with the use of gold nanospheres. Selective tumor labeling with gold nanospheres may be a strategy for clinically enhancing radiation effects.

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Technical note: Monte‐Carlo dosimetry of the HDR 12i and Plus sources

Cited by 66 publications

References 4 publications

Gafchromic film dosimetry of a new HDR brachytherapy source

Gafchromic film dosimetry of a new HDR brachytherapy source

Influence of phantom material and dimensions on experimental dosimetry

Quantifying tumor-selective radiation dose enhancements using gold nanoparticles: a monte carlo simulation study

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