Document Type: Original Paper
Department of Technology of Radiology and Radiotherapy, School of Allied Medical Sciences, Tehran University of Medical Sciences, Tehran, Iran
Technology of Radiology and Radiotherapy Department Allied Medical Sciences School, Tehran University of Medical Sciences, Tehran, Iran
Technology of Radiology and Radiotherapy Department, Allied Medical Sciences School, Tehran University of Medical Sciences, Tehran, Iran
The rapid growth of utilization of computed tomography (CT) scans is of great concern, due to significant increase in radiation exposure to patients. Optimizing cranial CT protocol, is vital in patient dose reduction. This study aimed to optimize radiation dose in cranial CT and to assess modifications in resultant image quality at reduced radiation dose.
Materials and Methods
A polymethyl methacrylate (PMMA) phantom was used for quality control test on CT scanners. Data of 214 scan parameters, volume CT dose index (CTDIvol) and dose length product (DLP) of patients who had cranial CT scans were collected and grouped into three with respect to slice numbers (N=24, 28 and 32). Tube voltage (kVp) and slice thickness (T) were constant; (110 kVp and T=4.8mm), at variable tube current (mAs). One sample t-test analysis was used to compare CTDIvol and DLP values of the hospital protocol with recommended protocol. Scan parameters were investigated for optimization of radiation dose against image quality.
Increased mAs resulted to increased CTDIvol and DLP at constant kVp and T. CTDIvol and DLP recorded lowest and highest values at N=24 and N=32, respectively. It was observed that increase in slice numbers affected CTDIvol and DLP. Employing optimized parameters, CTDIvol and DLP were significantly reduced statistically (p