Determination of 137Cs dosimetry parameters according to the AAPM TG-43 formalism

Abstract

Traditional treatment planning systems calculate dose distributions around 137Cs intracavitary sources by interpolating stored dose rate tables or by Sievert-type integrals. Some of the recently introduced planning systems, such as the Varian BrachyVision and Eclipse (Varian Medical Systems, Palo Alto, CA), have discontinued the use of tables and have implemented instead the AAPM TG-43 formalism as a brachytherapy dosimetry calculation algorithm. In this work we present the dosimetry parameters for 137Cs intracavitary sources as determined according to the TG-43 formalism. With the availability of the TG-43 parameters, the commissioning of a 137Cs source in any current brachytherapy planning system is a straightforward task for a clinical physicist.

TG‐43 U1 based dosimetric characterization of model 67‐6520 Cs‐137 brachytherapy source

“…Other published data regarding the TG-43 or TG-43 U1 based dosimetric parametrizations of different 137 Cs source pertains to models CSM11, 13 CSM3-a, 14 CSM2, and CSM3, 15 Walstam CDC.K type, 16 CDC-type miniature, 17 and the Selectron pellet. 18 Liu et al 19 determined the dosimetric parameters of the CSM-type 137 Cs sources based on the original TG-43 formalism. Pérez-Calatayud et al 20 also obtained the two-dimensional ͑2D͒ dose rate distribution around the CSM-type 137 Cs sources and compared their results with the calculated parameters by Liu et al 19 As the production of several of the above noted sources have been discontinued, a new 137 Cs source design has been introduced ͑model 67-6520, source B3-561͒ by Isotope Products Laboratories ͑IPL͒ to meet the demand of the current clinical procedures.…”

“…18 Liu et al 19 determined the dosimetric parameters of the CSM-type 137 Cs sources based on the original TG-43 formalism. Pérez-Calatayud et al 20 also obtained the two-dimensional ͑2D͒ dose rate distribution around the CSM-type 137 Cs sources and compared their results with the calculated parameters by Liu et al 19 As the production of several of the above noted sources have been discontinued, a new 137 Cs source design has been introduced ͑model 67-6520, source B3-561͒ by Isotope Products Laboratories ͑IPL͒ to meet the demand of the current clinical procedures. To date, there is no publication on the dosimetric parametrizations of this new source model.…”

A Review on Main Defects of TG-43

“…Since the publication of TG-43 formalism, many investigations have been performed on determination of the dosimetry parameters of brachytherapy sources and verification of its advantages and limitations of this protocol (Liu et al,2004;Meigooni et al, 2003Meigooni et al, , 2005Melhus & Rivard, 2006;Parsai et al, 2009;Rivard et al, 2004Rivard et al, , 2007Sina et al, 2007Sina et al, , 2009Sina et al, , 2011Song & Wu, 2008;). …”

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

“…6 Liu et al have published the TG-43 recommended dosimetric characteristics of the sources in this system. 12 In this study, from a set of 8 pellets, numbers 2-7 are considered active, and the remainders are non-active, in order to deliver 1.5 Gy of dose to 0.5 cm distance from the lateral surface of ovoids within 1.01 h.…”

“…19,20 Dosimetric characteristics of the single pellets from each system have been evaluated using the TG-43 protocols by different investigators. 12,21 For both Selectron and GZP6 unit film dosimetry with the new phantom at multiple levels relative to the GYN applicators were done. We compared dose calculation of film dosimetry from some interesting points with treatment planning.…”