The CNR method in scan angle optimization of tomosynthesis and its limitations

Baorui Ren; Chris Ruth; Yiheng Zhang; Andrew Smith; Cornell Williams; Brad Polischuk; Zhenxue Jing

doi:10.1117/12.813918

29 April 2009 The CNR method in scan angle optimization of tomosynthesis and its limitations

Baorui Ren, Chris Ruth, Yiheng Zhang, Andrew Smith, Cornell Williams, Brad Polischuk, Zhenxue Jing

Proceedings Volume 7258, Medical Imaging 2009: Physics of Medical Imaging; 72585W (2009) https://doi.org/10.1117/12.813918
Event: SPIE Medical Imaging, 2009, Lake Buena Vista (Orlando Area), Florida, United States

Abstract

The performance optimization of tomosynthesis is very challenging as it involves multiple system parameters to be optimized towards multiple figures of merit (FOM). Common approach is to take a selected few FOMs and optimize them under more confined conditions. While this kind of study helps us to gain more insights, extra precautions are needed when one tries to generalize the conclusions. Several reported works have shown that increasing the scan angle improves the contrast to noise ratio (CNR), which made the authors conclude that from the CNR perspective, large scan angle has advantages over small angle in tomosynthesis. In this study, we investigated the dependence of CNR on the scan angle while other system parameters were fixed. We found that improvement of CNR with large scan angle in those published studies was actually due to reconstruction algorithm and associated filtering effect but not due to the scan angle itself. To reveal this property, we selected six filters to cover a board range of possible shapes, and showed CNR variations with different filters. Besides, we also studied the ML-EM and SART iterative reconstruction algorithms, and obtained their equivalent Fourier filters numerically. The change of the equivalent filter shapes of iterative methods at different scan angle explained the observed CNR dependence on the scan angles. We conclude that larger scan angle does not have any intrinsic CNR advantage over small one in tomosynthesis. The observed CNR gain at large angle is an effect from the reconstruction filters. Therefore CNR based optimization study need to be carried out without the potential bias from filters.

Citation Download Citation

Baorui Ren, Chris Ruth, Yiheng Zhang, Andrew Smith, Cornell Williams, Brad Polischuk, and Zhenxue Jing "The CNR method in scan angle optimization of tomosynthesis and its limitations", Proc. SPIE 7258, Medical Imaging 2009: Physics of Medical Imaging, 72585W (29 April 2009); https://doi.org/10.1117/12.813918

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available