Computed Tomography (CT) scans result in higher radiation dose deposition compared to conventional radiology exams. These tests significantly contribute to both individual and collective radiation exposure, making them a global public health concern. Therefore, optimizing imaging protocols is essential to reduce radiation doses while preserving diagnostic image quality. The development of phantoms plays a crucial role in evaluating and refining different acquisition protocols to achieve this balance.To ensure accurate representation, phantoms must exhibit X-ray absorption characteristics similar to those of the human head. In this study, two cylindrical polymethylmethacrylate (PMMA) head phantoms were tested. One was a standard CT head phantom with a 16 cm diameter, while the other, a newly developed smaller phantom, had a 12 cm diameter. Both phantoms measured 15 cm in length.CT scans were conducted using a GE LightSpeed VCT scanner with 64 channels, employing various acquisition protocols. The central slice of each phantom was irradiated multiple times, and a pencil ionization chamber was used to measure the CT air kerma index in PMMA (Ck,PMMA,100) and the CT dose index (CTDI). Based on these measurements, the weighted and volumetric CT dose index values (CTDIw and CTDIvol) were determined for 10 cm scan lengths in helical mode. Scans were performed at different voltage levels (80, 100, and 120 kV) and varying tube current-time products (mAs). Using routine head scan protocols, the absorbed dose (CTDIvol) ranged from 39.22 to 49.67 mGy. However, optimized protocols resulted in absorbed doses between 20.89 and 31.93 mGy, achieving a reduction of up to 57.94% in the smaller 12 cm phantom.