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Multichannel Vaginal Cylinder Commissioning and Dosimetric Evaluation

K Dou1*, B Li1, F Lerma1, M Jacobs2, A Halthore2 (1) MedStar Health RadAmerica, Baltimore, MD, (2) Mercy Medical Center Radiation Oncology, Baltimore, MD

Presentations

(Sunday, 7/12/2020)   [Eastern Time (GMT-4)]

Room: AAPM ePoster Library

Purpose:
Multichannel Vaginal cylinder (MCVC) brachytherapy has potential to well sculpture radiation dose to the target because of the MCVC physical structure of a central channel together with multiple peripheral channels. This MCVC design allows more flexibility for dose optimization to the target over the single channel vaginal cylinder (SCVC) while sparing dose to nearby organs at risk. The current work presents MCVC commissioning and dosimetric evaluation.


Methods:
Integrity and design specifications of each cylinder were assessed with physical measurements and CT scans. The dwell source position of the cuffed catheters was verified with a source position simulator and Gafchromic film EBT3. Dose verification was performed with a Gafchromic film EBT3 and hand calculation. An Elekta Oncentra version 4.5.3 was served as a planning system. A study for the lesions as function of depth from 5mm to 10mm was carried out for dosimetric evaluation using a 3cm multichannel cylinder. MCVC versus SCVC dosimetry was compared in terms of the OAR’s dose at 2cc (D2cc) and at 1% of the OAR’s volume.

Results:
Physical dimensions and source dwell positions for the applicators were found to meet manufacturer specifications. Integrity checks revealed no cracks or damage to any part of the applicators. All measured dose points versus calculated ones were consistent within 7 %. MCVC versus SCVC in the 5 mm depth was reduced by about 20% in rectum dose for both D2cc and 1% vol. For the depth range of 7 to 10mm MCVC achieved a significant drop in rectum dose compared to SCVC by about 35% for D2cc and 1% vol and similarly by about 15% drop in bladder dose.

Conclusion:
MCVC was successfully commissioned for clinical application. MCVC is able to sculpture dose to the target based on treatment length, depth, and target volume while sparing organs at risk.

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Keywords

HDR, Intracavitary Brachytherapy

Taxonomy

TH- Brachytherapy: HDR Brachytherapy

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