The Influence of Pitch Factor in Reducing Computed Tomography Head Dose Exposure: Single–Centre Trials

Abstract

Computed tomography (CT) is mainly associated with high radiation dose exposure to patient and potential for increased risk of cancer. The increasing number of CT head examinations worldwide shows the need for optimization and strategy for dose reduction technique. Thus, the aim of this study is to evaluate the influence of pitch factor in reducing CT dose particularly CT head examination. In this study, the scan acquisition parameter and the CT dose parametric information were collected retrospectively from 16-slice CT scanner (Toshiba Activion) console display. Effective dose (E) was estimated using effective dose per dose-length product (E/DLP) conversion factor, k = 0.0021 mSv/mGy.cm. This experiment involved two sets of study, the pre-intervention (n = 163, 58 ± 18 years, 120 kV, 200 mAs, pitch = 0.688) and post-intervention (n = 165, 57 ± 19 years, 120 kV, 200 mAs, pitch = 0.938) on January 2017 and March 2017, respectively. The mean CTDI_vol values recorded for pre- and post-intervention were 70.00 ± 8.84 mGy and 51.30 ± 0.72 mGy, respectively. Generally, the mean E value for pre-intervention and post-intervention were 2.75 ± 0.35 mSv and 2.16 ± 0.17 mSv, respectively. It is interesting to note that by increasing the pitch factor in CT head examination has significantly reduced the CT head dose exposure without adversely affecting image quality. The mean DLP value for post-intervention is 1030.10 mGy.cm and has been set as institutional DRL. In conclusion, it is recommended for radiology personnel especially radiographer and radiologist to be aware certain acquisition parameters i.e. pitch factor that work for the optimization process.