Monte Carlo dosimetry of HDR brachytherapy sources

Abstract

Monte Carlo based dosimetry is presented for three 60Co HDR sources with a unique configuration of two active pellets in contact or spaced 9 and 11 mm apart. Results are presented in Cartesian "away and along" as well as polar coordinates following the AAPM TG-43 dosimetric formalism. Iso-dose rate contours around the sources in Cartesian coordinates reveal that significant differences between the three source designs exist only close to the source centers where dose rate distributions bear the effect of the unique source configurations. Dose rate constants of all three sources are accurately described by an equation of the form: lambda(cGyh(-1)U(-1))=lambda*pointG(1 cm,90 degrees) = 1.094*G(1 cm,90 degrees) where lambdapoint is the dose rate constant of a bare 60Co point source and G(1 cm,90 degrees) is the "exact" source geometry factor as defined by the TG-43. Radial dose and anisotropy function data extracted using the point source approximated geometry factors are tabulated for all three source designs. Finally, the dependence and variation of the above TG-43 parameters are discussed and it is demonstrated that the dosimetric properties of high-energy photon emitters are largely dependent on radionuclide source distribution.

Comparison of 60Cobalt and 192Iridium Sources in High Dose Rate Afterloading Brachytherapy

“…There is good agreement between Monte Carlo calculations of the radial dose function g L (r) in our model and the data provided by other authors [1,5,17] and the data implemented in the commercial treatment planning system as seen in Figure 3. This figure contains additionally the radial dose function g P (r) for both nuclides [3].…”

“…Dosimetric and theoretical studies supported clinical equivalence [3,7,11,13,17]. 60 Co and 192 Ir sources of identical shape and construction show practically identical dose distributions despite definite differences in physical characteristics.…”

“…The dose calculation in clinical brachytherapy is based on the AAPM TG43 algorithm [17]. The calculation of the dose rate Ḋ (r, θ) of a source X (X = L for a line source, X = P for a point source) at an arbitrary point P(r, θ) follows the equation…”

Dose distribution verification for GYN brachytherapy using EBT Gafchromic film and TG-43 calculation

“…EBT Gafchoromic film dosimetry for two different brachytherapy systems for GYN treatment were considered in this study: the GZP6 high dose rate (HDR) 60 Co brachytherapy unit that was introduced by Nuclear Power Institute of China for brachytherapy procedures, 5 and the Selectron low-dose-rate (LDR) 137 Cs remote afterloading system distributed by Nucletron (Nucletron BV, Veenendaal, The Netherlands). 6…”

Errors in Fitting Radial Dose Function of Cobalt Sources for Brachytherapy With 3-5 Degree Polynomials

“…При этом точность определения коэффициентов данной функции должна быть такова, чтобы погрешность аппроксимации была не хуже 2%. В большинстве работ [3][4][5][6], даже если приводятся коэффициенты аппроксимации, не указывается точность аппроксимации, а также точность определения коэффициентов аппрокси-мации и возможная неопределенность функции аппроксимации. Встречаются работы, в которых предлагается аппроксимировать радиальную до-зовую функцию полиномами меньшего порядка [7][8].…”