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A Novel and Innovative Device to Retract Rectum During Radiation Therapy Applications of Pelvic Tumors

E Parsai1, G Giri2*, M Elahinia3, P Bayatimalayeri4, D Elliott5, (1) University of Toledo Medical Center, Toledo, OH, (2) University Of Toledo, ,,(3) University of Toledo, Toledo, ,(4) University of Toledo, Toledo, OH, (5) University of Toledo Medical Center, Toledo,

Presentations

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

Room: AAPM ePoster Library

Purpose:
The Rectal Retractor is an innovative and minimally invasive device that employs the actuation of a shape memory alloy (SMA) to move the rectum away from the vicinity of radiation fields during the radiotherapy of pelvic tumors.

Methods:
The Retractor device is designed using a Nickel-Titanium (also called Nitinol) actuator. Nitinol is a SMA capable of precisely and consistently achieving a specific range of pre-set motions when thermally activated. The new prototype consists of SMA actuator, heating elements and controller, and is shaped like a fork with two balloon sets designed to open the fingers and to grab the rectal tissue before actuation. The Nitinol wire is activated by mini electric heating elements and actuates to a pre-defined shape, moving the rectal tissue posteriorly, away from radiation field.

Results:
The Retractor device has undergone numerous mathematical modeling and cadaveric testing to refine and enhance the design. Initial designs faced complications because of unaccounted anatomical anomalies as well as problems related to poor grasp of rectal tissues. Further refinements included newly designed fork shaped and proper placement of balloons to allow for more reliable and even inflations as well as avoiding coccyx bone as the device moves in posterior direction. At the completion of radiotherapy procedure, current is stopped and the device returns tissue to its original position. Balloons are deflated, and device is removed from the rectum.

Conclusion:
Our team has successfully demonstrated effective retraction of rectum using an improved Retractor prototype after numerous iterations via simulation, bench top, and cadaveric validation studies. We have shown that by utilizing the final design prototype, one can successfully and safely retract the rectal tissue away from the radiation field. The device can be implemented for all pelvic tumors to move rectum effectively, safely, and comfortably to a safe distance.

Download ePoster [PDF]

Keywords

Organ Motion, Radiation Protection

Taxonomy

TH- External Beam- Photons: extracranial stereotactic/SBRT

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