Dual resolution cone beam breast CT: a feasibility study.
OBJECTIVE
In this study, the authors investigated the feasibility of a dual resolution volume-of-interest (VOI) cone beam breast CT technique and compared two implementation approaches in terms of dose saving and scatter reduction.


METHODS
With this technique, a lead VOI mask with an opening is inserted between the x-ray source and the breast to deliver x-ray exposure to the VOI while blocking x rays outside the VOI. A CCD detector is used to collect the high resolution projection data of the VOI. Low resolution cone beam CT (CBCT) images of the entire breast, acquired with a flat panel (FP) detector, were used to calculate the projection data outside the VOI with the ray-tracing reprojection method. The Feldkamp-Davis-Kress filtered backprojection algorithm was used to reconstruct the dual resolution 3D images. Breast phantoms with 180 microm and smaller microcalcifications (MCs) were imaged with both FP and FP-CCD dual resolution CBCT systems, respectively. Two approaches of implementing the dual resolution technique, breast-centered approach and VOI-centered approach, were investigated and evaluated for dose saving and scatter reduction with Monte Carlo simulation using a GEANT4 package.


RESULTS
The results showed that the breast-centered approach saved more breast absorbed dose than did VOI-centered approach with similar scatter reduction. The MCs in fatty breast phantom, which were invisible with FP CBCT scan, became visible with the FP-CCD dual resolution CBCT scan.


CONCLUSIONS
These results indicate potential improvement of the image quality inside the VOI with reduced breast dose both inside and outside the VOI.
Chen
Lingyun
L
Department of Imaging Physics, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030-4009, USA. lingyun.chen@di.mdacc.tmc.edu
Shen
Youtao
Y
Lai
Chao-Jen
CJ
Han
Tao
T
Zhong
Yuncheng
Y
Ge
Shuaiping
S
Liu
Xinming
X
Wang
Tianpeng
T
Yang
Wei T
WT
Whitman
Gary J
GJ
Shaw
Chris C
CC
D000465:Algorithms; D001940:Breast / Q000528:radiation effects; D001943:Breast Neoplasms / Q000000981:diagnostic imaging*; D002114:Calcinosis / Q000000981:diagnostic imaging; D003198:Computer Simulation; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D008327:Mammography / Q000379:methods*; D009010:Monte Carlo Method; D010232:Paraffin / Q000737:chemistry; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D012542:Scattering, Radiation; D012984:Software; D014965:X-Rays
D010232:Paraffin