Half-Fan-Based Intensity-Weighted Region-of-Interest Imaging for Low-Dose Cone-Beam CT in Image-Guided Radiation Therapy.
10.4258/hir.2016.22.4.316
- Author:
Boyeol YOO
1
;
Kihong SON
;
Rizza PUA
;
Jinsung KIM
;
Alexander SOLODOV
;
Seungryong CHO
Author Information
1. Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Daejeon, Korea. scho@kaist.ac.kr
- Publication Type:Original Article
- Keywords:
Cone-Beam Computed Tomography;
Low-Dose;
Region-of-Interest;
Half-Fan;
Image-Guided Radiation Therapy
- MeSH:
Cone-Beam Computed Tomography*;
Copper;
Humans;
Image Processing, Computer-Assisted;
Methods;
Pelvis;
Radiation Exposure;
Radiotherapy, Image-Guided*
- From:Healthcare Informatics Research
2016;22(4):316-325
- CountryRepublic of Korea
- Language:English
-
Abstract:
OBJECTIVES: With the increased use of computed tomography (CT) in clinics, dose reduction is the most important feature people seek when considering new CT techniques or applications. We developed an intensity-weighted region-of-interest (IWROI) imaging method in an exact half-fan geometry to reduce the imaging radiation dose to patients in cone-beam CT (CBCT) for image-guided radiation therapy (IGRT). While dose reduction is highly desirable, preserving the high-quality images of the ROI is also important for target localization in IGRT. METHODS: An intensity-weighting (IW) filter made of copper was mounted in place of a bowtie filter on the X-ray tube unit of an on-board imager (OBI) system such that the filter can substantially reduce radiation exposure to the outer ROI. In addition to mounting the IW filter, the lead-blade collimation of the OBI was adjusted to produce an exact half-fan scanning geometry for a further reduction of the radiation dose. The chord-based rebinned backprojection-filtration (BPF) algorithm in circular CBCT was implemented for image reconstruction, and a humanoid pelvis phantom was used for the IWROI imaging experiment. RESULTS: The IWROI image of the phantom was successfully reconstructed after beam-quality correction, and it was registered to the reference image within an acceptable level of tolerance. Dosimetric measurements revealed that the dose is reduced by approximately 61% in the inner ROI and by 73% in the outer ROI compared to the conventional bowtie filter-based half-fan scan. CONCLUSIONS: The IWROI method substantially reduces the imaging radiation dose and provides reconstructed images with an acceptable level of quality for patient setup and target localization. The proposed half-fan-based IWROI imaging technique can add a valuable option to CBCT in IGRT applications.
