A real‐time applicator position monitoring system for gynecologic intracavitary brachytherapy. Issue 1 (12th December 2013)

• Record Type: Journal Article
• Authors: Xia, Junyi; Waldron, Timothy; Kim, Yusung
• Is Part Of: Medical physics. Volume 41:Issue 1(2014)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2013-12-12
• Subjects: Therapeutic applications, including brachytherapy -- Magnetic resonance imaging; biomedical MRI -- brachytherapy -- cameras -- gynaecology -- medical image processing -- patient monitoring -- phantoms; brachytherapy -- applicator motion -- monitoring and verification -- quality assurance; Involving electronic [emr] or nuclear [nmr] magnetic resonance, e.g. magnetic resonance imaging -- Radiation therapy -- Biological material, e.g. blood, urine; Haemocytometers -- Details of cameras or camera bodies; Accessories therefor -- Cameras -- Digital computing or data processing equipment or methods, specially adapted for specific applications -- Image data processing or generation, in general -- Scintigraphy; Cameras -- Medical imaging -- Infrared detectors -- Brachytherapy -- Three dimensional image processing -- Dosimetry -- Computed tomography -- Magnetic resonance imaging -- Radiation treatment; Medical physics -- Periodicals; Medical physics; Geneeskunde; Natuurkunde; Toepassingen; Biophysics; Periodicals; Periodicals; Electronic journals; 610.153
• DOI: 10.1118/1.4842555
• Languages: English
• ISSNs: 0094-2405

Abstract

Abstract : Purpose: : To develop a real‐time applicator position monitoring system (RAPS) for intracavitary brachytherapy using an infrared camera and reflective markers. Methods: : 3D image‐guided brachytherapy requires high accuracy of applicator localization; however, applicator displacement can happen during patient transfer for imaging and treatment delivery. No continuous applicator position monitoring system is currently available. The RAPS system was developed for real‐time applicator position monitoring without additional radiation dose to patients. It includes an infrared camera, reflective markers, an infrared illuminator, and image processing software. After reflective markers are firmly attached to the applicator and the patient body, applicator displacement can be measured by computing the relative change in distance between the markers. The reflective markers are magnetic resonance imaging (MRI) compatible, which is suitable for MRI‐guided HDR brachytherapy paradigm. In our prototype, a Microsoft Kinect sensor with a resolution of 640 by 480 pixels is used as an infrared camera. A phantom study was carried out to compare RAPS' measurements with known displacements ranging from −15 to +15 mm. A reproducibility test was also conducted. Results: : The RAPS can achieve 4 frames/s using a laptop with Intel ® Core™2 Duo processor. When the pixel size is 0.95 mm, the difference between RAPS' measurements and known shift values varied from 0 to 0.8 mm with the mean value of 0.1 mm and a standard deviation of 0.44 mm. The system reproducibility was within 0.6 mm after ten reposition trials. Conclusions: : This work demonstrates the feasibility of a real‐time infrared camera based gynecologic intracavitary brachytherapy applicator monitoring system. Less than 1 mm accuracy is achieved when using an off‐the‐shelf infrared camera.