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Improved compressed sensing-based cone-beam CT reconstruction using adaptive prior image constraints

Authors
 Ho Lee  ;  Lei Xing  ;  Ran Davidi  ;  Ruijiang Li  ;  Jianguo Qian  ;  Rena Lee 
Citation
 PHYSICS IN MEDICINE AND BIOLOGY, Vol.57(8) : 2287-2307, 2012 
Journal Title
 PHYSICS IN MEDICINE AND BIOLOGY 
ISSN
 0031-9155 
Issue Date
2012
MeSH
Algorithms ; Cone-Beam Computed Tomography/methods* ; Head and Neck Neoplasms/diagnostic imaging ; Humans ; Image Processing, Computer-Assisted/methods* ; Radiation Dosage
Abstract
Volumetric cone-beam CT (CBCT) images are acquired repeatedly during a course of radiation therapy and a natural question to ask is whether CBCT images obtained earlier in the process can be utilized as prior knowledge to reduce patient imaging dose in subsequent scans. The purpose of this work is to develop an adaptive prior image constrained compressed sensing (APICCS) method to solve this problem. Reconstructed images using full projections are taken on the first day of radiation therapy treatment and are used as prior images. The subsequent scans are acquired using a protocol of sparse projections. In the proposed APICCS algorithm, the prior images are utilized as an initial guess and are incorporated into the objective function in the compressed sensing (CS)-based iterative reconstruction process. Furthermore, the prior information is employed to detect any possible mismatched regions between the prior and current images for improved reconstruction. For this purpose, the prior images and the reconstructed images are classified into three anatomical regions: air, soft tissue and bone. Mismatched regions are identified by local differences of the corresponding groups in the two classified sets of images. A distance transformation is then introduced to convert the information into an adaptive voxel-dependent relaxation map. In constructing the relaxation map, the matched regions (unchanged anatomy) between the prior and current images are assigned with smaller weight values, which are translated into less influence on the CS iterative reconstruction process. On the other hand, the mismatched regions (changed anatomy) are associated with larger values and the regions are updated more by the new projection data, thus avoiding any possible adverse effects of prior images. The APICCS approach was systematically assessed by using patient data acquired under standard and low-dose protocols for qualitative and quantitative comparisons. The APICCS method provides an effective way for us to enhance the image quality at the matched regions between the prior and current images compared to the existing PICCS algorithm. Compared to the current CBCT imaging protocols, the APICCS algorithm allows an imaging dose reduction of 10-40 times due to the greatly reduced number of projections and lower x-ray tube current level coming from the low-dose protocol.
Full Text
http://iopscience.iop.org/article/10.1088/0031-9155/57/8/2287/meta
DOI
10.1088/0031-9155/57/8/2287
Appears in Collections:
1. College of Medicine (의과대학) > Dept. of Radiation Oncology (방사선종양학교실) > 1. Journal Papers
Yonsei Authors
Lee, Ho(이호) ORCID logo https://orcid.org/0000-0001-5773-6893
URI
https://ir.ymlib.yonsei.ac.kr/handle/22282913/158280
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