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Image Based Treatment Planning for Intraluminal Brachytherapy in Bile Duct Carcinoma

S Chaudhari

S Chaudhari*, R Engineer, D Deshpande, S Shrivastava, TATA MEMORIAL HOSPITAL, Mumbai, Maharshtra

SU-E-T-460 Sunday 3:00PM - 6:00PM Room: Exhibit Hall

Purpose:3D Image based treatment planning for intraluminal brachytherapy in bile duct carcinoma.

Methods:Five patients with bile duct carcinoma were treated with definitive radiation therapy. Radiation therapy was delivered by means of external beam radiation therapy (EBRT) combined with HDR brachytherapy.
Eclipse v8.6 TPS (Varian Medical Systems, USA) was used for treatment planning.
In the diagnostic radiology suite, a flexible guide wire was passed through the biliary stent to a point past the stenosis. Subsequently catheter localisation, dummy wire was inserted and orthogonal films were used to confirm the position.
All the patients were scanned on CT scanner (Siemens, Germany) with a slice thickness of 3 mm without any radio opaque dummy. The GTV, CTV OAR were contoured according to ICRU 62.
Since the catheter is inserted in biliary stent, the applicator reconstruction is not possible. The first source point was reconstructed from the tip of the stent. From the orthogonal topograph the offset was calculated by measuring the tip of the stent to first dummy source distance. This offset was set in the planning. With the optimum source length the dose was calculated and CTV, OAR doses were quantified. The External and brachytherapy plans were summed to produce resultant DVH.

Results:The applicator reconstruction accuracy was found to be within ±2mm. The mean, median dose of GTV, CTV was 32Gy, 23Gy and 18Gy, 13Gy respectively. The mean, median dose for duodenum was 7.6Gy and 2.8Gy.

Conclusion:In radiography assisted planning, dose distribution is usually calculated according to the applicator geometry and in addition to fixed reference points. But with 3D brachytherapy planning the doses can be optimised to GTV and can be summed with external plan for clinical evaluation.

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