Developing a Treatment Planning Software Based on TG-43U1 Formalism for Cs-137 LDR Brachytherapy


Sedigheh Sina 1 , Reza Faghihi 2 , * , Ali Soleimani Meigooni 3 , Zahra Siavashpour 4 , Mohammad Amin Mosleh-Shirazi 6

1 Radiation Research Center, Shiraz University, Shiraz, IR Iran

2 Department of Nuclear Engineering, Shiraz University, Shiraz, IR Iran

3 Comprehensive Cancer Center of Nevada, Las Vegas, Nevada, USA

4 Department of Radiation Medicine, Shahid Beheshti University, Tehran, IR Iran

6 Department of Radiotherapy and Oncology, Shiraz University of Medical Sciences, Shiraz, IR Iran

How to Cite: Sina S, Faghihi R, Soleimani Meigooni A, Siavashpour Z, Mosleh-Shirazi M A. Developing a Treatment Planning Software Based on TG-43U1 Formalism for Cs-137 LDR Brachytherapy, Iran Red Crescent Med J. Online ahead of Print ; 15(8):712-717. doi: 10.5812/ircmj.4938.


Iranian Red Crescent Medical Journal: 15 (8); 712-717
Published Online: August 4, 2013
Article Type: Research Article
Received: April 12, 2012
Accepted: June 13, 2013


Background: The old Treatment Planning Systems (TPSs) used for intracavitary brachytherapy with Cs-137 Selectron source utilize traditional dose calculation methods, considering each source as a point source. Using such methods introduces significant errors in dose estimation. As of 1995, TG-43 is used as the main dose calculation formalism in treatment TPSs.

Objectives: The purpose of this study is to design and establish a treatment planning software for Cs-137 Solectron brachytherapy source, based on TG-43U1 formalism by applying the effects of the applicator and dummy spacers.

Materials and Methods: Two softwares used for treatment planning of Cs-137 sources in Iran (STPS and PLATO), are based on old formalisms. The purpose of this work is to establish and develop a TPS for Selectron source based on TG-43 formalism. In this planning system, the dosimetry parameters of each pellet in different places inside applicators were obtained by MCNP4c code. Then the dose distribution around every combination of active and inactive pellets was obtained by summing the doses. The accuracy of this algorithm was checked by comparing its results for special combination of active and inactive pellets with MC simulations. Finally, the uncertainty of old dose calculation formalism was investigated by comparing the results of STPS and PLATO softwares with those obtained by the new algorithm.

Results: For a typical arrangement of 10 active pellets in the applicator, the percentage difference between doses obtained by the new algorithm at 1cm distance from the tip of the applicator and those obtained by old formalisms is about 30%, while the difference between the results of MCNP and the new algorithm is less than 5%.

Conclusions: According to the results, the old dosimetry formalisms, overestimate the dose especially towards the applicators tip. While the TG-43U1 based software perform the calculations more accurately.

© 2013, Author(s). This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License ( which permits copy and redistribute the material just in noncommercial usages, provided the original work is properly cited.

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