2D/3D registration algorithm for lung brachytherapy

• Published in: Medical physics (Lancaster) Vol. 40; no. 2; pp. 021913 - n/a
• Main Authors: Zvonarev, P. S., Farrell, T. J., Hunter, R., Wierzbicki, M., Hayward, J. E., Sur, R. K.
• Format: Journal Article
• Language: English
• Published: United States American Association of Physicists in Medicine 01.02.2013
• Subjects: 2D/3D registration; 60 APPLIED LIFE SCIENCES; Algorithms; BRACHYTHERAPY; Brachytherapy - methods; Cancer; catheters; Catheters; Hollow probes; Computed tomography; Computerised tomographs; computerised tomography; COMPUTERIZED TOMOGRAPHY; data analysis; Digital computing or data processing equipment or methods, specially adapted for specific applications; Digitization; DOSE RATES; Dosimetry; Humans; Image data processing or generation, in general; image matching; IMAGE PROCESSING; image registration; Imaging, Three-Dimensional - methods; lung; lung brachytherapy; Lung Neoplasms - diagnostic imaging; Lung Neoplasms - radiotherapy; LUNGS; medical image processing; Medical imaging; Medical X‐ray imaging; PATIENTS; PHANTOMS; Phantoms, Imaging; Radiation therapy; RADIOLOGY AND NUCLEAR MEDICINE; Radiotherapy Dosage; Radiotherapy, Image-Guided - methods; Registration; SENSITIVITY; Therapeutic applications, including brachytherapy; Time Factors; Tomography, X-Ray Computed; X RADIATION; X‐ray imaging; computed tomography; lung brachytherapy; 2D/3D registration
• ISSN: 0094-2405; 2473-4209; 2473-4209
• DOI: 10.1118/1.4788663

Purpose: A 2D/3D registration algorithm is proposed for registering orthogonal x-ray images with a diagnostic CT volume for high dose rate (HDR) lung brachytherapy. Methods: The algorithm utilizes a rigid registration model based on a pixel/voxel intensity matching approach. To achieve accurate registration, a robust similarity measure combining normalized mutual information, image gradient, and intensity difference was developed. The algorithm was validated using a simple body and anthropomorphic phantoms. Transfer catheters were placed inside the phantoms to simulate the unique image features observed during treatment. The algorithm sensitivity to various degrees of initial misregistration and to the presence of foreign objects, such as ECG leads, was evaluated. Results: The mean registration error was 2.2 and 1.9 mm for the simple body and anthropomorphic phantoms, respectively. The error was comparable to the interoperator catheter digitization error of 1.6 mm. Preliminary analysis of data acquired from four patients indicated a mean registration error of 4.2 mm. Conclusions: Results obtained using the proposed algorithm are clinically acceptable especially considering the complications normally encountered when imaging during lung HDR brachytherapy.