Audit Dosis dan Optimisasi Pemeriksaan CT Scan Kepala: Studi Multisenter

Abstract

One of the principles of radiation protection is optimizing radiation dose and image quality. Dose audits and optimization of head CT scans for the adult patient category have been carried out in Hospital A and Hospital B. The research at Hospital A started with a dose audit, revealing that the typical values of CTDIvol and DLP were above the IDRL, and optimization of patient radiation dose was necessary. The optimization strategy at Hospital A involved a gradual selection of exposure factor combinations. In the first stage, a manufactured dedicated water phantom scan was performed with voltage 80, 100, and 120 kVp variations while the current remained constant. Based on image quality evaluation using the Noise Power Spectrum (NPS) method, the lowest NPS was obtained at voltage 120 kV, which was 19,47 HU2mm2. In the second stage, using voltage 120 kVp, a head rando phantom scan was performed with variations of current 100, 150, 200, 250, 300, 350, 400, and 450 mAs. 40% of the radiologists chose the exposure factor combination voltage 120 kVp and current 350 mAs as the combination producing image with the most preferable quality. When comparing the voltage and current combinations before and after optimization with the IDRL, there was a decrease of 7.9% and 2.1% in CTDIvol and DLP. Meanwhile, the dose audit results at Hospital B revealed that the typical value of CTDIvol was already below the IDRL. Still, the typical value of DLP was above the IDRL, so optimization of patient radiation dose for patient-related parameters was necessary. The optimization strategy at Hospital B involved creating new protocols based on exposure factors obtained from image quality evaluation using the NPS method and the interpretation of radiologists. The optimization results with a comparison of four protocols showed that protocol 3 was the most optimal using the exposure factors: collimation 40 × 0.625, the pitch of 0.2, the scan time of 13.8 seconds, Dose Right Index of 25, voltage 120 kVp, and current 144 mAs. The implementation of this protocol contributed to a 67.7% reduction in CTDIvol and a 53.6% reduction in DLP compared to the IDRL. The research objective is to obtain the optimal combination of exposure factors with radiation dosage and image quality as an initial optimization implementation. Keywords: dose audit, radiation protection, optimization, diagnostic reference levels