Nnamdi Odinakachukwu Emeka Okoro defended his Thesis titledImage Quality against Radiation Dose Reduction in Cranial Computed Tomography (CT): A Practical method in Optimizing and Standardizing CT Protocols in a Tehran Hospital, Iran.

The rapid use of computed tomography (CT) is of great concern, due to significant increase in patient dose, that could cause deterministic effects like cataracts. Optimizing CT protocols without loss of diagnostic image quality, is vital in patient dose reduction. In this study, performance of one of the Tehran university’s hospitals was investigated as regards to radiation dose reduction and image quality. To evaluate hospital performance, the image quality and radiation dose of applied protocol for cranial CT were recorded and compared with AAPM protocol. One sample t-test analysis was used to compare applied protocol with AAPM protocol. An optimization of CT parameters (kVp, mAs and slice thickness) was performed with respect to better diagnostic image quality and dose reduction. Increase in mAs at constant kVp and slice thickness resulted to increase in CTDIvol and DLP. Though the applied parameters were lower than the AAPM protocols, images produced were of reasonable diagnostic value. As it was expected, elevation of slice number led to increase in CTDIvol and DLP. Applied protocols were statistically significant (P < 0.001) compared to AAPM protocols as regards to kVp, mAs, slice thickness and CTDIvol. Image quality was assessed and satisfied by two radiologists. AAPM protocols for cranial CT are oriented towards best image quality, but with high patient dose. Using our optimized protocols has shown to decrease patient dose without loss of diagnostic image quality.



Supervisors: Dr. Vahid Changizi & Dr Farideh Pak.

Advisor: Dr Elahe Jazeyeri

External Reviewers: Dr Susan Cheraghi & Mr Rahim Faramarzi