Whole-body examinations in PET/CT were performed on a sample of 368 patients, 203 males and 165 females. Mean values, standard deviation (SD), minimum and maximum values of patient’s age, weight, height, body mass index (BMI) administered activities, CTDI_vol and DLP, are presented in Table 1.

The mean, median and 75th percentiles for CTDI_vol were 5.12 mGy, 4.59 mGy and 6.03 mGy, respectively. The mean value of activity was 355.05 MBq, as well the median was 358.45 MBq. The estimation of Pearson’s coefficient revealed a strong positive correlation between the following pair of parameters. The Pearson’s coefficient (r) between BMI and CTDI_vol was estimated 0.84, BMI and activity was 0.69, CTDI_vol and activity was 0.65, and CTDI_vol and BMI was 0.78.

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Table 1. Mean values ± standard deviation (SD), minimum and maximum values of patient’s age, weight, height, BMI, administered activity, CTDI_vol and DLP.

Figure 1 illustrates the distribution of CTDI_vol values according to BMI of the patients.

Fig. 1: Distribution of CTDIvol values.

Figure 1: Distribution of CTDI_vol values.

Figures 2 and 3 display frequency histograms of CTDI_vol values for PET/CT whole body examinations (n=368) and the injected ¹⁸F-FDG activity, respectively. In both cases, the distribution is skewed and asymmetric with a main peak, tail and some extreme values.[5]

Fig. 2: Histogram of CTDIvol values for PET/CT whole body examinations.

Figure 2: Histogram of CTDI_vol values for PET/CT whole body examinations.

Fig. 3: Histogram of injected FDG activity.

Figure 3: Histogram of injected FDG activity.