Designing a phantom for dose evaluation in multi-slice CT

Samir Abboud; Andreu Badal; Stanley H. Stern; Iacovos S. Kyprianou

doi:10.1117/12.844355

22 March 2010 Designing a phantom for dose evaluation in multi-slice CT

Samir Abboud, Andreu Badal, Stanley H. Stern, Iacovos S. Kyprianou

Proceedings Volume 7622, Medical Imaging 2010: Physics of Medical Imaging; 762232 (2010) https://doi.org/10.1117/12.844355
Event: SPIE Medical Imaging, 2010, San Diego, California, United States

Abstract

Accurately representing radiation dose delivered in MSCT is becoming a concern as the maximum beam width of some modern CT scanners tends to become wider than the 100 mm charge-collection length of the pencil ionization chamber generally used in CT dosimetry. We investigate two alternative methods of dose evaluation in CT scanners. We investigate two alternative approaches for better characterization of CT dose than conventional evaluation of CTDI₁₀₀. First, we simulate dose profiles and energy deposition in phantoms longer than the typically used 14-15 cm length right-circular cylinders. Second we explore the accuracy and practicality of applying mathematical convolution to a scatter kernel in order to generate dose profiles. A basic requirement for any newly designed phantom is that it be able to capture approximately the same dose as would an infinitely long cylinder, but yet be of a size and weight that a person could easily carry and position. Using the PENELOPE Monte Carlo package, we simulated dose profiles in cylindrical polymethyl methacrylate (PMMA) phantoms of 10, 16, 20, 24 and 32 cm diameter and 15, 30 and 300 cm length. Beam widths were varied from 1 cm to 60 cm. Lengths necessary to include within the dose integrals values associated with the scatter tails as well as with the primary radiation of the profile were then calculated as the full width at five percent of maximum dose. The resulting lengths suggest that to accommodate wide beam widths, phantoms longer than those currently used are necessary. The results also suggest that using a longer phantom is a relatively more accurate approach, while using mathematical convolution is simpler and more practical to implement than using the long phantoms designed according to direct Monte Carlo simulations.

Citation Download Citation

Samir Abboud, Andreu Badal, Stanley H. Stern, and Iacovos S. Kyprianou "Designing a phantom for dose evaluation in multi-slice CT", Proc. SPIE 7622, Medical Imaging 2010: Physics of Medical Imaging, 762232 (22 March 2010); https://doi.org/10.1117/12.844355

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