Modeling scattered radiation from dose compensator in CT by forced detection Monte Carlo simulation

Negar Bazargani; Richard A. Thompson; Yoad Yagil

doi:10.1117/12.911514

3 March 2012 Modeling scattered radiation from dose compensator in CT by forced detection Monte Carlo simulation

Negar Bazargani, Richard A. Thompson, Yoad Yagil

Proceedings Volume 8313, Medical Imaging 2012: Physics of Medical Imaging; 83132L (2012) https://doi.org/10.1117/12.911514
Event: SPIE Medical Imaging, 2012, San Diego, California, United States

Abstract

We model the scatter radiation from the dose compensator in computed tomography (CT) using Monte Carlo (MC) simulation. Dose compensator reduces the patient radiation dose but also adds some scatter radiation which can reach detectors and degrade image quality. This scattered radiation impacts high contrast edges such as bone-soft tissue and tissue-air interfaces, similar to the well known off-focal radiation from the X-ray tube. To the best of our knowledge, this is the first study that uses MC simulation to model and investigate the compensator scatter radiation. Since detectors are far from the scatter source and have small solid angle, traditional MC is not computationally efficient. We have implemented variance reduction technique called forced detection (FD) to improve the computational efficiency, and achieved an improvement factor of 42,800. The simulated scatter to primary ratio (SPR) ranges from a few percent to 11% across the detectors. Simulations of water phantoms indicate that such scatter can lead to significant effects along edges as large as 20-30 HU, necessitating the need for correction. We demonstrate a correction in FBP reconstruction, somewhat similar to off-focal correction, and show that it significantly reduces the level of the artifact along the edge of the phantom.

Citation Download Citation

Negar Bazargani, Richard A. Thompson, and Yoad Yagil "Modeling scattered radiation from dose compensator in CT by forced detection Monte Carlo simulation", Proc. SPIE 8313, Medical Imaging 2012: Physics of Medical Imaging, 83132L (3 March 2012); https://doi.org/10.1117/12.911514

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