Monte Carlo calculation of dose rate distributions around  wires

Ballester, F.; Hernández, Candela; Pérez‐Calatayud, José; Lliso, F.

doi:10.1118/1.598142

Cited by 59 publications

(65 citation statements)

References 21 publications

(22 reference statements)

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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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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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“…The ‫ء‬ F8 energy deposition tally was used to score the absorbed dose and the forced collision variance reduction technique was used to increase the number of charged particles in the vicinity of the scoring regions. 24 While the F6 collision kerma tally has been shown to be equivalent to absorbed dose from 192 Ir sources at distances beyond the first few millimeters, 28,29 the F6 collision kerma tally is not appropriate near the surface or at material boundaries where charged particle equilibrium does not exist.…”

Section: Methodsmentioning

confidence: 99%

Determination of exit skin dose for intracavitary accelerated partial breast irradiation with thermoluminescent dosimeters

et al. 2010

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Purpose: Intracavitary accelerated partial breast irradiation ͑APBI͒ has become a popular treatment for early stage breast cancer in recent years due to its shortened course of treatment and simplified treatment planning compared to traditional external beam breast conservation therapy. However, the exit dose to the skin is a major concern and can be a limiting factor for these treatments. Most treatment planning systems ͑TPSs͒ currently used for high dose-rate ͑HDR͒ 192Ir brachytherapy overestimate the exit skin dose because they assume a homogeneous water medium and do not account for finite patient dimensions. The purpose of this work was to quantify the TPS overestimation of the exit skin dose for a group of patients and several phantom configurations. Methods: The TPS calculated skin dose for 59 HDR 192 Ir APBI patients was compared to the skin dose measured with LiF:Mg,Ti thermoluminescent dosimeters ͑TLDs͒. Additionally, the TPS calculated dose was compared to the TLD measured dose and the Monte Carlo ͑MC͒ calculated dose for eight phantom configurations. Four of the phantom configurations simulated treatment conditions with no scattering material beyond the point of measurement and the other four configurations simulated the homogeneous scattering conditions assumed by the TPS. Since the calibration TLDs for this work were irradiated with 137 Cs and the experimental irradiations were performed with 192 Ir, experiments were performed to determine the intrinsic energy dependence of the TLDs. Correction factors that relate the dose at the point of measurement ͑center of TLD͒ to the dose at the point of interest ͑basal skin layer͒ were also determined and applied for each irradiation geometry. Results: The TLD intrinsic energy dependence for 192 Ir relative to 137 Cs was 1.041Ϯ 1.78%. The TPS overestimated the exit skin dose by an average of 16% for the group of 59 patients studied, and by 9%-15% for the four phantom setups simulating treatment conditions. For the four phantom setups simulating the conditions assumed by the TPS, the TPS calculated dose agreed well with the TLD and MC results ͑within 3% and 1%, respectively͒. The inverse square geometry correction factor ranged from 1.023 to 1.042, and an additional correction factor of 0.978 was applied to account for the lack of charged particle equilibrium in the TLD and basal skin layer. Conclusions: TPS calculations that assume a homogeneous water medium overestimate the exit skin dose for intracavitary APBI treatments. It is important to determine the actual skin dose received during intracavitary APBI to determine the skin dose-response relationship and establish dose limits for optimal skin sparing. This study has demonstrated that TLDs can measure the skin dose with an expanded uncertainty ͑k =2͒ of 5.6% when the proper corrections are applied.

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“…These scoring voxels/cells assure volume averaging artifacts <0.1% for distances greater than 5 mm from the source. [18] The scored energy in water was converted to air kerma by multiplication of the ratio of mass attenuation coefficients of air and water. Air attenuation and scattering was corrected with the factor 1.012.…”

Section: Methodsmentioning

confidence: 99%

Monte Carlo study of dosimetric parameters and dose distribution effect of inhomogeneities and source position of GammaMed Plus source

Chandola

Tiwari

Painuly³

et al. 2011

J Can Res Ther

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Monte Carlo calculation of dose rate distributions around wires

Cited by 59 publications

References 21 publications

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

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

Determination of exit skin dose for intracavitary accelerated partial breast irradiation with thermoluminescent dosimeters

Monte Carlo study of dosimetric parameters and dose distribution effect of inhomogeneities and source position of GammaMed Plus source

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