46 H. Khajmi et al.: Radioprotection 2025, 60( 1), 44 – 49
Table 1. Data obtained in this study, including mean, minimum, and maximum, as well as percentiles for CTDI vol( mGy) and DLP( mGy. cm) numbers found.
Exposure parameters |
CT exams |
|
Head |
CAP |
Chest |
Abdomen |
Voltage( kV) |
[ 120 – 120 ] |
[ 120 – 120 ] |
[ 120 – 120 ] |
[ 120 – 120 ] |
Intensity( mAs) |
[ 270 – 270 ] |
[ 45 – 180 ] |
[ 48 – 244 ] |
[ 17 – 71 ] |
Thickness( mm) |
[ 5 – 10 ] |
[ 5 – 10 ] |
[ 5 – 10 ] |
[ 5 – 10 ] |
Pitch |
[ 0.55 – 1.5 ] |
[ 0.55 – 1.5 ] |
[ 0.55 – 1.5 ] |
[ 0.55 – 1.5 ] |
Mean CTDI vol( mGy) |
38 |
7 |
9 |
7 |
Min CTDI vol( mGy) |
36 |
3 |
3 |
5 |
Max CTDI vol( mGy) |
44 |
12 |
17 |
12 |
50 th CTDI vol( mGy) |
34 |
6 |
7 |
7 |
75 th CTDI vol( mGy) |
40 |
8 |
11 |
9 |
Mean DLP( mGy. cm) |
1422 |
710 |
598 |
454 |
Min DLP( mGy. cm) |
1281 |
354 |
333 |
121 |
Max DLP( mGy. cm) |
1724 |
1222 |
874 |
1021 |
50 th DLP( mGy. cm) |
1390 |
695 |
612 |
704 |
75 th DLP( mGy. cm) |
1445 |
825 |
700 |
788 |
Table 2. Estimated 75 th percentile of CTDI vol( mGy) and DLP( mGy. cm) numbers for head, CAP, chest, and abdomen CTs in this work compared to other countries.
Examinations DRL 75th percentile
CTDI vol
( mGy)
Head CAP Chest Abdomen
DLP( mGy. cm)
CTDI vol
( mGy)
DLP( mGy. cm)
CTDI vol
( mGy)
DLP( mGy. cm)
CTDI vol
( mGy)
This work |
40 |
1445 |
8 |
825 |
11 |
700 |
9 |
788 |
ICRP 2017 |
60 |
1050 |
– |
– |
30 |
650 |
35 |
780 |
French, 2018 |
46 |
850 |
11 |
750 |
10 |
350 |
13 |
650 |
USA, 2015 |
62 |
1120 |
– |
– |
17 |
610 |
17 |
860 |
Japan, 2020 |
77 |
1350 |
16 |
1200 |
13 |
510 |
18 |
880 |
Ethiopia, 2021 |
43 |
1364 |
– |
– |
8 |
369 |
11 |
1569 |
China, 2020 |
50 |
818 |
– |
– |
8 |
302 |
10 |
442 |
Sudan, 2018 |
41 |
461 |
– |
– |
9 |
165 |
8 |
270 |
UK, 2014 |
55 |
760 |
– |
– |
10 |
430 |
13 |
460 |
DLP( mGy. cm) kVp at levels beyond the internationally advised threshold. In reality, the dosage distribution in a CT scan may be affected by taking into account the patient’ s gender, skull shape, and size.
The CTDI vol for CAP CT varied from 3 mGy to 12 mGy, with a mean of 7 mGy and the DLP ranges from 354 mGy. cm to 1222 mGy. cm, with a mean of 710 mGy. cm. The CTDI vol and DLP at the 75th percentiles for CT of the chest to pelvis CT were 8 mGy and 825 mGy. cm, respectively. The DRLs of chest to pelvis CT in terms of CTDI vol in this research is lower than the DRL observed in Japan in 2020( Kanda et al., 2021) and in French in 2018( Roch et al., 2018). Japan in 2020( Kanda et al., 2021) has the highest DRL( 1200 mGy) of DLP values.
The estimated CTDI vol for chest CT ranged from 3 mGy to 17 mGy, with a mean of 9 mGy, and the DLP ranged from 333 mGy. cm to 874 mGy. cm, with a mean of 598 mGy. cm. Figure 2 presents the frequency distribution of DLP( mGy. cm) of the chest CT. This histogram displays a homogenous distribution of DLP values-albeit one that is neither gaussian or normal. The DRL of CTDI vol of chest CT is 11 mGy in this study, it is moderately more than those found in earlier research from the UK noted in 2014( Shrimpton et al., 2014), Sudan 2018( Bashier et al., 2018), China 2020( Li et al., 2020), Ethiopia 2021( Zewdu et al., 2021), and French 2018( Roch et al., 2018). However, the level was very lower than that of the ICRP in 2017( ICRP, 2017)( 173 %), USA( 54.5 %)( Smith- Bindman et al., 2015), and Japan( 18 %)( Kanda et al., 2021) studies. The DLP at the 75 th percentile for chest CT is 700 mGy. cm, it was above than all different publications proposed DRLs. The age of the scanners, institutionally favoured procedures, availability of dose reduction algorithms, and variations in scan lengths can all be factors contributing to variations in dosimetric results for chest CT scans among studies( Arlany et al., 2023).