M . Keshtkar : Radioprotection 2024 , 59 ( 2 ), 131 – 137 133 Table 1 . CT scanning parameters of two protocols for three age groups . Group age ( years ) Protocol CT protocol parameters
Tube potential ( kVp ) Tube current ( mAs ) Slice thickness ( mm ) Nominal beam width ( mm ) pitch
< 5 |
RC-CT |
80 , 110 |
52.8 ± 12.9 |
5 |
16 1.2 |
1.25 – 1.5 |
|
CD-CT |
80 , 110 |
27.8 ± 9.7 |
5 |
16 1.2 |
1.25 – 1.5 |
5 –< 10 |
RC-CT |
110 , 130 |
59.7 ± 10.5 |
5 |
16 1.2 |
1 – 1.5 |
|
CD-CT |
110 , 130 |
31.4 ± 11.1 |
5 |
16 1.2 |
1 – 1.5 |
10 – 15 |
RC-CT |
110 , 130 |
67.8 ± 14.7 |
5 |
16 1.2 |
1 – 1.5 |
|
CD-CT |
110 , 130 |
35.7 ± 13.5 |
5 |
16 1.2 |
1 – 1.5 |
Table 2 . Demographic data and values of effective diameter . Group age ( years ) Sex CT protocol Number Age ( years ) Effective diameter ( cm ) P value
G1 (< 5 ) |
Male |
RC-CT |
13 |
2.9 ± 1.0 |
15.1 ± 2.6 |
0.594 |
|
|
CD-CT |
13 |
2.7 ± 0.9 |
15.3 ± 2.3 |
|
|
Female |
RC-CT |
14 |
3.1 ± 1.1 |
13.9 ± 1.2 |
0.841 |
|
|
CD-CT |
14 |
2.9 ± 1.0 |
14.2 ± 0.9 |
|
G2 ( 5 –< 10 ) |
Male |
RC-CT |
23 |
7.7 ± 1.3 |
19.9 ± 1.9 |
0.332 |
|
|
CD-CT |
23 |
7.6 ± 1.2 |
20.5 ± 2.1 |
|
|
Female |
RC-CT |
21 |
7.1 ± 1.4 |
17.9 ± 1.8 |
0.117 |
|
|
CD-CT |
21 |
7.3 ± 1.1 |
17.3 ± 1.7 |
|
G3 ( 10 – 15 ) |
Male |
RC-CT |
29 |
13.1 ± 1.8 |
23.8 ± 2.3 |
0.117 |
|
|
CD-CT |
29 |
13.0 ± 1.5 |
24.2 ± 2.6 |
|
|
Female |
RC-CT |
27 |
12.8 ± 1.7 |
20.4 ± 2.3 |
0.472 |
|
|
CD-CT |
27 |
13.0 ± 1.7 |
19.1 ± 1.7 |
|
Table 3 . Data on CTDIvol , DLP , effective dose and SSDE .
Group age ( years ) Dose descriptors ( Mean ± SD ) CTDI vol ( mGy ) DLP ( mGy . cm ) Effective dose ( mSv ) SSDE ( mGy )
|
RC-CT |
CD-CT |
RC-CT |
CD-CT |
RC-CT |
CD-CT |
RC-CT |
CD-CT |
G1 (< 5 ) |
2.4 ± 0.6 |
1.1 ± 0.4 |
58.7 ± 14.3 |
26.7 ± 12.2 |
1.4 ± 0.6 |
0.9 ± 0.2 |
4.5 ± 1.2 |
2.1 ± 0.5 |
G2 ( 5 –< 10 ) |
2.9 ± 0.4 |
1.3 ± 0.3 |
75.9 ± 11.8 |
34.5 ± 9.8 |
1.8 ± 0.8 |
1.1 ± 0.2 |
5.5 ± 1.2 |
2.5 ± 0.6 |
G3 ( 10 – 15 ) |
3.3 ± 0.9 |
1.5 ± 0.3 |
87.1 ± 15.3 |
39.6 ± 12.7 |
1.9 ± 2.3 |
1.2 ± 0.3 |
5.7 ± 2.1 |
2.6 ± 0.5 |
Data on dose descriptors such as CTDIvol , DLP , effective dose and SSDE are summarized in Table 3 . The lowest values of CTDI vol were 2.4 ± 0.6 mGy and 1.1 ± 0.4 mGy for RC-CT and CD-CT protocols in the G1 group , respectively . The highest values of CTDI vol were 3.3 ± 0.9 mGy and 1.5 ± 0.3 mGy for RC-CT and CD-CT protocols in the G3 group , respectively .
The lowest values of DLP ( mGy . cm ) were 58.7 ± 14.3 and 26.7 ± 12.2 for RC-CT and CD-CT protocols in the G1 group , respectively . The highest values of DLP ( mGy . cm ) were 87.1 ± 15.3 and 39.6 ± 12.7 for RC-CT and CD-CT protocols in the G3 group , respectively .
The lowest values of effective dose were 1.4 ± 0.6 mSv and 0.9 ± 0.2 mSv for RC-CT and CD-CT protocols in the G1 group , respectively . The highest values of effective dose were
1.9 ± 2.3 mSv and 1.2 ± 0.3 mSv for RC-CT and CD-CT protocols in the G3 group , respectively .
The lowest values of SSDE were 4.5 ± 1.2 mGy and 2.1 ± 0.5 mGy for RC-CT and CD-CT protocols in the G1 group , respectively . The highest values of SSDE were 5.7 ± 2.1 mGy and 2.6 ± 0.5 mGy for RC-CT and CD-CT protocols in the G3 group , respectively . The statistical analysis showed that the SSDE was lower in the CD-CT protocol group compared to the RC-CT protocol group for all three age groups ( P < 0.05 ).
Figure 1 presents organ doses for G1 , G2 , and G3 . For the males , the lungs received the highest organ dose ( 4.27 ± 1.4 mGy ) in the RC-CT protocol of the G3 age group . Also , for the females , the lungs received the highest organ dose ( 3.90 ± 1.23 mGy ) in the RC-CT protocol of the G3 age group .