MR-CBCT image-guided system for radiotherapy of orthotopic rat prostate tumors.

Publisher: Public Library of Science Country of Publication: United States NLM ID: 101285081 Publication Model: eCollection Cited Medium: Internet ISSN: 1932-6203 (Electronic) Linking ISSN: 19326203 NLM ISO Abbreviation: PLoS One Subsets: MEDLINE

Original Publication: San Francisco, CA : Public Library of Science

Cone-Beam Computed Tomography* ; Magnetic Resonance Imaging*; Prostatic Neoplasms/*diagnostic imaging ; Prostatic Neoplasms/*radiotherapy ; Radiotherapy, Image-Guided/*methods; Animals ; Image Processing, Computer-Assisted ; Male ; Phantoms, Imaging ; Radiotherapy Planning, Computer-Assisted ; Rats

Multi-modality image-guided radiotherapy is the standard of care in contemporary cancer management; however, it is not common in preclinical settings due to both hardware and software limitations. Soft tissue lesions, such as orthotopic prostate tumors, are difficult to identify using cone beam computed tomography (CBCT) imaging alone. In this study, we characterized a research magnetic resonance (MR) scanner for preclinical studies and created a protocol for combined MR-CBCT image-guided small animal radiotherapy. Two in-house dual-modality, MR and CBCT compatible, phantoms were designed and manufactured using 3D printing technology. The phantoms were used for quality assurance tests and to facilitate end-to-end testing for combined preclinical MR and CBCT based treatment planning. MR and CBCT images of the phantoms were acquired utilizing a Varian 4.7 T scanner and XRad-225Cx irradiator, respectively. The geometry distortion was assessed by comparing MR images to phantom blueprints and CBCT. The corrected MR scans were co-registered with CBCT and subsequently used for treatment planning. The fidelity of 3D printed phantoms compared to the blueprint design yielded favorable agreement as verified with the CBCT measurements. The geometric distortion, which varied between -5% and 11% throughout the scanning volume, was substantially reduced to within 0.4% after correction. The distortion free MR images were co-registered with the corresponding CBCT images and imported into a commercial treatment planning software SmART Plan. The planning target volume (PTV) was on average 19% smaller when contoured on the corrected MR-CBCT images relative to raw images without distortion correction. An MR-CBCT based preclinical workflow was successfully designed and implemented for small animal radiotherapy. Combined MR-CBCT image-guided radiotherapy for preclinical research potentially delivers enhanced relevance to human radiotherapy for various disease sites. This novel protocol is wide-ranging and not limited to the orthotopic prostate tumor study presented in the study.
Competing Interests: The authors have declared that no competing interests exist.

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P41 RR002584 United States RR NCRR NIH HHS; United States RA ARRA NIH HHS; P41 EB015908 United States EB NIBIB NIH HHS; P30 CA142543 United States CA NCI NIH HHS; S10 RR028011 United States RR NCRR NIH HHS; U24 CA126608 United States CA NCI NIH HHS

Date Created: 20180531 Date Completed: 20181126 Latest Revision: 20201214

20231215

PMC5976174

10.1371/journal.pone.0198065

29847586