Development of 192Ir HDR brachytherapy phantom for dosimetric verification and source positioning accuracy

Authors

  • Jettapat Tarasub Division of Radiology, King Chulalongkorn Memorial Hospital
  • Nesara Pattanaphan Radiology Department, Samitivej Sukhumvit Hospital
  • Sakda Kingkaew Division of Radiation Oncology, Department of Radiology, King Chulalongkorn Memorial Hospital
  • Lukkana Apipunyasopon Department of Radiological Technology and Medical Physics, Faculty of Allied Health Sciences, Chulalongkorn University

Keywords:

High dose rate brachytherapy, Remote after-loading system, Optically stimulated luminescence dosimeter, Gafchromic film

Abstract

Backgrounds: Brachytherapy is a treatment method in which an encapsulated radioactive source placed at short distance from the tumor to deliver the high radiation dose to the target while sparing normal tissues. Due to its steep dose gradient, the lack of proper monitoring system has led to treatment delivery errors. Therefore, the development of device for verifying the dose delivery and the source positon accuracy is essential.

Objective: The main objective of this study was to develop a prototype phantom for dosimetric measurement and source positioning check in 192Ir high dose-rate (HDR) brachytherapy treatment.

Materials and Methods: The phantom size of 30×30×5 cm3 was designed on shapr3D application and built from acrylic material. It was composed of a single channel for source placement via needle applicator, 20 slots for holding the Optically stimulated luminescence dosimeter (OSLD), and a single slot for placing the film. The computed tomography of our phantom was acquired and imported into the Oncentra treatment planning system (TPS). The test plan was created and delivered into the phantom using the Flexitron HDR afterloader. The source dwell position and calculate absorbed dose was investigated by the Gafchromic EBT3 film and nanoDots OSLD, respectively.

Results: The phantom was rigid and simple enough to be used for dosimetric measurement with OSLD and assessing the source dwell position with Gafchromic film. The average CT number of the phantom was equal to 149.86±3.89 HU. The deviations of the source position were observed to be within ±1 mm. The average difference in point dose between the OSLD measurement and TPS calculation was 4.40±2.51%.

Conclusion: Our phantom can be used as a routinely checking tool for assessing the source position and the delivered dose in the quality control procedure of 192Ir brachytherapy unit.

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Published

2021-09-21

How to Cite

1.
Tarasub J, Pattanaphan N, Kingkaew S, Apipunyasopon L. Development of 192Ir HDR brachytherapy phantom for dosimetric verification and source positioning accuracy. J Thai Assn of Radiat Oncol [Internet]. 2021 Sep. 21 [cited 2024 Mar. 29];27(2):R43-R59. Available from: https://he01.tci-thaijo.org/index.php/jtaro/article/view/250025

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