Congress:
EuroSafe Imaging 2021
Keywords:
Cardiac, Head and neck, Radioprotection / Radiation dose, CT, Diagnostic procedure, Calcifications / Calculi, Dosimetric comparison, Trauma
Authors:
D. P. Ivanova, M. Nedevska, D. Kostova-Lefterova, V. Groudeva, K. Romanova
DOI:
10.26044/esi2021/ESI-10764
Results or findings
The patient data presented in Table 1 is collected on the 320-slice CT system between 2018 and 2020. The total number of the patients is 91 (55% - women and 45% - men).
The analyses show that the median CTDIvol and DLP values (and the standard deviation), per phase, for the contrast cardiac CT phase, 320-slice CT system and trot=0.375 s are: 46.5 (21.4) mGy and 740.6 (342.8) mGy.cm. For the same CT system and faster trot=0.35 s, the median CTDIvol and DLP values are 1.4 times lower: 34.0 (16.2) mGy and 543.6 (258.9) mGy.cm.
The additional exposure parameters and patient data are presened in Table 1.
The patient data shown in Table 2 is collected on the 16-slice CT system during 2018. The total number of the patients included in the study is 30 (43% - women and 57% - men).
The results for the median CTDIvol and DLP values (and the standard deviation), per phase for the CT head examinations, performed with patients on a 16-slice CT system and trot=2 s are: 92.6 (10.2) mGy and 1314.7 (188.2) mGy.cm. For the same CT system and faster trot=1 s, the results are 1.3 times lower: 69.8 (14.3) mGy and 1102.6 (217.1) mGy.cm.
A phantom study is performed (Figure 1 – b) on the 320-slice CT system. The CTDIvol and DLP median values, per phase for the CT head examinations performed are: 106.0 mGy and 1495.0 mGy.cm (trot=1.5 s); 70.0 mGy and 1013.0 mGy.cm (trot=1 s) and 35 mGy and 510 mGy.cm (trot=0.5 s) [Table 3].
The results from the image quality are the following: with trot = 1.5 s, SNR and CNR are respectively: 60 and 39, with trot = 1.0 s, SNR and CNR are 1.2 times lower: 49 and 32, while with trot = 0.5 s, SNR and CNR are 1.5 times lower: 33 and 21. These results show that SNR and CNR decrease with increasing trot. This means that increasing trot does not lead to images which are acquired with the best image quality and also the noise is increased, but the total radiation exposure time and patient exposure are reduced (Figure 7).
The estimated radiologic risk was considered as “low” for all CT examinations included in the current investigation.