Dosimetric evaluation of a novel high dose rate (HDR) intraluminal / interstitial brachytherapy applicator for gastrointestinal and bladder cancers

Abstract

High dose rate (HDR) brachytherapy is one of the accepted treatment modalities in gastro‐intestinal tract and bladder carcinomas. Considering the shortcoming of contact brachytherapy routinely used in gastrointestinal tract in treatment of big tumors or invasive method of bladder treatment, an intraluminal applicator with the capability of insertion into the tumor depth seems to be useful. This study presents some dosimetric evaluations to introduce this applicator to the clinical use. The radiation attenuation characteristics of the applicator were evaluated by means of two dosimetric methods including well‐type chamber and radiochromic film. The proposed 110 cm long applicator has a flexible structure made of stainless steel for easy passage through lumens and a needle tip to drill into big tumors. The 2 mm diameter of the applicator is thick enough for source transition, while easy passage through any narrow lumen such as endoscope or cystoscope working channel is ensured. Well‐chamber results showed an acceptably low attenuation of this steel springy applicator. Performing absolute dosimetry resulted in a correlation coefficient of normalR=0.9916false(normalp‐value≈10−7false) between standard interstitial applicator and the one proposed in this article. This study not only introduces a novel applicator with acceptable attenuation but also proves the response independency of the GAFCHROMIC EBT films to energy. By applying the dose response of the applicator in the treatment planning software, it can be used as a new intraluminal / interstitial applicator.PACS number: 87.53.Bn, 87.53.Jw, 29.40.Cs

Film based verification of calculation algorithms used for brachytherapy planning-getting ready for upcoming challenges of MBDCA

“…One such method involves the use of externally generated photon beams, which was the easiest calibration method to implement. However, even though this calibration method was common [ 25 , 26 , 27 ], its use has been abandoned. Chiu-Tsao et al .…”

Zastosowanie filmów radiochromowych w weryfikacji rozkładów dawek w brachyterapii. Przygotowanie do wprowadzenia algorytmów zaproponowanych przez TG-186 AAPM.

“…W ten sposób autorzy kilku publikacji przy użyciu wygenerowanych wiązek kilo-bądź megawoltowych tworzyli krzywe kalibracyjne, na podstawie których określali dawkę na filmach Grzegorz Bielęda / Zeszyty Naukowe WCO, Letters in Oncology Science 2017;14 (1): [39][40][41][42][43][44] napromienionych źródłem o innej energii [19,20]. Ten sposób kalibracji filmów nie wydaje się jednak właściwy.…”