| NUKLEONIKA 2011, 56(4):299-304
SIMULATION OF COMPUTED TOMOGRAPHY (CT) IMAGES
USING A MONTE CARLO APPROACH
Anna M. Wysocka-Rabin1, Sima Qamhiyeh2, Oliver Jäkel2
1 Department of Accelerator Physics, The Andrzej Sołtan Institute for Nuclear Studies,
05-400 Otwock/Świerk, Poland
2 Department of Medical Physics, German Cancer Research Centre (DKFZ),
Im Neuenheimer Feld 280,
D-69120 Heidelberg, Germany
Heavy ion treatment planning uses an empirical scanner-dependent calibration relation between computed tomography (CT) numbers and ion range. Any deviation in the values of CT numbers will cause a drift in the calibration curve of the CT scanner, which can reduce the accuracy of treatment beam delivery. To reduce uncertainty in the empirical estimation of CT numbers, we developed a simulation that takes into consideration the geometry, composition, and physical process that underlie their measurement. This approach uses Monte Carlo (MC) simulations, followed by a simple filtered back-projection reconstruction. The MC code used is BEAMnrc/EGSnrc. With the manufacturer’s permission,
we simulated the components (X-ray tube, associated filters and beam shapers) of a Siemens Emotion CT. We then generated an initial beam shape and spectra, and performed further simulations using the phantom with substitutes. We analyzed the resulting phase space file to calculate projections, taking into account the energy response of the CT detectors. Then, we applied a simple reconstruction algorithm to the calculated projections in order to receive the CT image.
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