Ahamad, Nor Fadhilah
(2015)
Comparison of CT number between conventional CBCT and imasim software.
Project Report.
Pusat Pengajian Sains Kesihatan, Universiti Sains Malaysia.
(Submitted)
Abstract
The aim of this study was to compare the CT number between the
conventional Cone Beam Computed Tomography (CBCT) and ImaSim simulation
software. The CT numbers in CBCT were performed by using CIRS 062 M electron
density phantoms with four types of tissue equivalent plug density phantoms
ranging from 0 g/cm3 to 1.61 g/cm3 based on the common tissues in the oral cavity.
The CT numbers of tissue equivalent density plugs were of air, adipose, water and
bone were compared between CBCT and ImaSim software at 80 kVp and 10 mAs.
15 slices of CBCT images with slice thickness of approximately 1.0 mm are
obtained from central axis of phantom were selected to measure the average CT
number by drawing a region of interest (ROI) on every slice. The images of ImaSim
were obtained by simulation of CBCT at similar phantom set up and CBCT
exposure factors. The measurement of chi-square 'goodness of fit' was used to
determine the closeness of CT numbers among theoretical, Planmeca Romexis
CBCT and ImaSim. The results showed that the x2 values of CT numbers of
theoretical value against Planmeca Romexis CBCT were between 0.651 and 5.206
while the x2 values of theoretical value against lmasim CBCT was between 3.738
and 42.201. However, the range of x2 for Planmeca Romexis CBCT vs lmaSim
CBCT was between 1.877 and 58.887. In conclusion, the high density tissues such
as bone gave the highest degree of closeness of CT numbers between Planmeca
Romexis CBCT and lmaSim. Therefore, low density tissues are best applied in
ImaSim CBCT simulation.
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