SU‐E‐T‐224: Dose Distribution of Oesophagus Stents Measured by EBT2 Film Dosimetry

• Published in: Medical Physics 2012-06, Vol.39 (6), p.3755-3755
• Main Authors: Poppinga, D, Schoenfeld, A, Chofor, N, Poppe, B
• Format: Article
• Language: English
• Subjects: Cancer; Cavitation; Dosimetry; Field size; Image scanners; Medical imaging; Nickel; Photons; Tissues; Titan
• ISSN: 0094-2405; 2473-4209
• DOI: 10.1118/1.4735287

Purpose: The purpose of this study is to investigate the dose enhancement at oesophagus stents made of nitinol. The material is a nickel titan alloy with an effective atomic number of 26. Because of the increased atomic number in comparison to the human body, dose enhancement in surrounding tissue is expected. Methods: The relative dose distribution around the stent was measured in a water phantom. To simulate the air cavity within the oesophagus, a styrodur cylinder was placed inside the stent. The stent was held with a circular PMMA holder. An EBT2 film was wrapped around the stent to measure the relative radial dose distribution.The setup was irradiated with a 6MV photon beam (Siemens Primus) and a field size of 5cmx5cm. The distance between source and centre of the stent was 100cm.The EBT2 films were digitized at a scanning resolution of 72dpi using an Epson 10000XL flatbed scanner with a transparency unit. Furthermore, the films were fixed in a frame to prevent Newton rings in the scanned image. Results: The dose increases in all directions around the stent. With approximately 18%, the highest increase is caused on the proximal side of the stent. On the backside the dose enhancement is approximately 10%. Conclusions: Dose enhancements around a stent are detectable and one should be aware of it's occurence in the radiotherapeutical treatment of oesophageal cancer. Because of the enhancement in all directions healthy tissue may be affected.