Rectal Retraction System for Prostate Radiotherapy
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Solution Overview
Problem
Current methods for immobilizing the prostate gland during radiotherapy, such as endorectal balloons and injectable spacers, face challenges in achieving reproducible rectal retraction and minimizing organ deformation, leading to potential rectal toxicity and complications.
Innovation Solution
A rectal retractor system that includes a probe body with radiation detectors and a removable sheath, allowing for active separation of the anterior rectal membrane from the prostate, providing reproducible setup and dose monitoring, while minimizing exposure to ionizing radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If endorectal balloons are inflated with air to expand the rectum, then the anterior rectal wall moves toward the prostate and displaces it frontally, but the mechanism raises the anterior surface of the rectum into the high dose region and deforms local anatomy
Solution Approach 1:
Instead of pushing the rectum forward with an inflated balloon (anterior displacement), the invention uses a retractor that pulls the rectum backward (posterior displacement). This inversion of the displacement direction moves the rectum away from the high-dose region while maintaining separation from the prostate, thereby reducing rectal radiation exposure without deforming local anatomy into the treatment field.
Solution Approach 2:
The invention extracts the rectum from the high-dose region by using a retractor device that physically separates the anterior rectal wall from the prostate gland. This extraction removes the harmful interaction between the rectum and the radiation field, allowing the prostate to be treated with high doses while the rectum is positioned in a low-dose zone.
2Reliability
If endorectal balloons are used to control rectum volume, then the prostate is indirectly immobilized, but reproducible rectal retraction and minimal organ deformation are not achieved
Solution Approach 1:
The invention replaces the mechanical inflation system of endorectal balloons with a retractor-based mechanical system. The retractor uses a pull mechanism rather than a push mechanism, providing more controlled and reproducible rectal retraction. This mechanical substitution allows for precise positioning of the rectum without the volume expansion and deformation associated with balloon inflation.
3Reliability
If large PTV margins are added to account for prostate motion, then accurate coverage of the prostate is ensured, but unacceptable late urinary and rectal complications develop
Solution Approach 1:
The invention performs preliminary action by immobilizing the prostate and separating the rectum from the prostate before radiation treatment begins. This preliminary immobilization and separation eliminate the need for large PTV margins, as the prostate position is stabilized and the rectum is positioned away from the high-dose region in advance, thereby ensuring accurate coverage without compromising adjacent organs.
4Object-affected harmful factors
If injectable spacers are used to increase distance between prostate and rectum, then rectal dose is significantly decreased, but transperineal incision or interstitial needle placement is required
Solution Approach 1:
The invention introduces a retractor device as an intermediary tool that facilitates rectal separation without requiring direct injection into the perineal tissue. The retractor is inserted through the anus and acts as a mediator to mechanically separate the rectum from the prostate, achieving the same protective effect as injectable spacers but through a less invasive transanal approach rather than transperineal incision or needle placement.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively immobilizes the prostate, reduces rectal exposure to high doses, and ensures accurate treatment delivery with minimal organ deformation, improving patient outcomes and reducing treatment-related complications.
Implementation Method 1
The probe body is dimensioned to separate a portion of the body cavity from the treatment region to reduce exposure of membranous tissue surrounding the body cavity to the at least one dose from the ionizing radiation source
Implementation Method 2
A plurality of radiation detectors are disposed along a proximal end of the probe body to measure at least one dose from the ionizing radiation source
Data Source
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AI summary
A system for monitoring doses from an ionizing radiation source to a treatment region of a patient and immobilizing a body cavity relative to the treatment region, is provided. The system includes a probe body for insertion into the body cavity. The probe body separates the body cavity from the treatment region to reduce exposure to doses from the ionizing radiation source. Radiation detectors are disposed along the probe body to measure at least one dose. A slot disposed adjacent the radiation detectors receives a dosimetry film that, upon exposure to the one or more doses from the ionizing radiation source, indicates a quantification of the doses. A coupling is in fluid communication with a removable sheath having coupled thereto a vacuum or a pump to remove fluid or gas from the body cavity and ensure inner wall of the body cavity is in contact with the sheath.