<![CDATA[In bone scan single-photon emission computed tomography/computed tomography (SPECT/CT), the CT provides the anatomical reference for localizing scintigraphic findings. Because automatic exposure control (AEC) modulates the tube current–time product (mAs) according to patient attenuation, CT image quality may differ between examinations. This study quantified CT image quality and examined its association with AEC-selected mAs. CT datasets from 72 patients at the Nuclear Medicine Unit of Dr. M. Djamil Hospital, Padang, were analyzed retrospectively. Mean CT number and image noise were measured in a hepatic region of interest to derive signal-to-noise ratio (SNR), and data were evaluated using correlation and simple linear regression. Mean mAs, liver CT attenuation, image noise, and SNR were 58.35 ± 16.24, 56.66 ± 8.55 HU, 2.14 ± 0.49 HU, and 27.57 ± 6.59, respectively. Body mass index (BMI) correlated positively with mAs (r = 0.642, p < 0.001). Moderate negative correlations were found between mAs and SNR (r = −0.468, p < 0.001) and between mAs and liver CT attenuation (ρ = −0.444, p < 0.001), whereas mAs and image noise were not significantly associated (ρ = 0.209, p = 0.078). Under AEC, mAs alone cannot adequately explain variability in quantitative CT image quality.]]>
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