Development of computed tomography reference doses for head and stonogram examinations at East Avenue Medical Center

Acceptable Quality Dose (AQD) is a facility-initiated optimization approach that considers three fundamental components of diagnostic imaging: dosimetry, image quality, and patient habitus. This study aimed to prove feasibility of AQD in clinical practice as an updated dose optimization reference, supplementary to the Diagnostic Reference Level (DRL). Specifically, it aimed to establish AQDs for selected CT procedures (i.e., stonogram, cranial for trauma, and head CT for acute stroke) of East Avenue Medical Center in Quezon City, analyze the trend of obtained AQD values in terms of patient mass, and compare the AQDs to those of typical DRL values. Displayed CT DRL quantities, i.e., volume CT Dose Index (CTDIvol) and dose-length product (DLP), were verified using CTDI phantom measurements. Typical DRL values were estimated by determining the median of the DRL quantities, as the International Commission on Radiological Protection recommended. We evaluated the image quality of all qualified CT studies using the image quality scoring criteria (IQSC). Out of 225 total examinations obtained, 76.0% were considered adequate in terms of image quality. The results showed an upward trend of AQD indices with increasing patient mass. CTDIvol (mGy) and DLP (mGy.cm) range between 8.84 to 17.54 and 353.82 to 772.69 for stonogram, and 48.10 to 69.38 and 833.39 to 1216.89 for cranial for trauma and head CT for acute stroke. Furthermore, the derived typical DRL values, CTDIvol (mGy) and DLP (mGy.cm), for selected CT procedures are as follows: 11.84 and 519.18 for stonogram, 59.74 and 1020.91 for cranial for trauma, and 49.71 and 900.73 for head CT for acute stroke. The mean (± SD) mass for each procedure is 56 kg (± 9.5), 57 (± 7.9) and 56kg (± 10.0) respectively. Establishing image quality-related reference doses is a practical approach to optimizing CT doses within a facility, especially in the absence of national DRL in the Philippines.