Radioprotection No 59-2 | Page 54

R . Sindi et al .: Radioprotection 2024 , 59 ( 2 ), 111 – 116 113

Table 1 . Radiation dose parameters in adult patients undergoing CT chest scans prior to NDRLs implementation .

Table 2 . Radiation dose parameters in adult patients undergoing CT chest scans post-NDRLs implementation .

221 of these scans ( 11.1 %) were with contrast and 731 scans ( 36.7 %) were without contrast . After NDRLs implementation , the number of scans with contrast was 208 ( 10.4 %), while those without contrast were 831 ( 41.7 %).

3.1 Results prior to NDRLs implementation

Prior to the implementation of NDRLs , the study documented varied radiation dose metrics for adult patients undergoing CT chest scans , with and without contrast , as shown in Table 1 . In adults undergoing non-contrast CT , kVp was 118.27 ± 5.26 , mAs was 1469 ± 578.84 , CTDIvol was 8.82 ± 3.38 mGy , DLP was 309.33 ± 131.18 mGy . cm . For contrast scans , kVp , mAs , CTDIvol and DLP were 101.35 ± 7.86 , 1604 ± 662.84 , 6.33 ± 2.69 mGy , and 239.98 ± 115.19 , respectively .

3.2 Results post-NDRLs implementation

After the implementation of NDRLs , the dose metrics for CT chest examinations showed changes across adult patients , and for both without and with contrast-enhanced scans , as shown in Table 2 . For patients undergoing CT chest examinations without contrast , the kVp was 118.33 ± 5.52 , the mAs was 1433.46 ± 530 , the CTDIvol was 8.72 ± 2.33 mGy , and the DLP was 301.86 ± 124.32 mGy cm . For patients undergoing CT chest examinations with contrastenhanced scans , the kVp was 100.76 ± 6.47 , the mAs was 1614 ± 684 , the CTDIvol was 6.20 ± 2.63 mGy , and the DLP was 233.8 ± 110.9 mGy cm .

3.3 Comparison of radiation dose parameters

The implementation of NDRLs has resulted in various changes in radiation dose parameters across different patient categories , as illustrated in Table 3 . In the cohort without contrast , the changes were slight , with a 0.05 % increase in kVp , decreases in mAs by 2.42 %, CTDIvol by 1.13 %, DLP by 2.41 %, and ED by 2.29 %. Chest CT with contrast-enhanced scans resulted in a 0.58 % decrease in kVp , a 0.62 % increase in mAs , and decreases in CTDIvol by 2.05 %, and DLP by 2.58 %.

3.4 Pass / fail distribution post-NDRLs implementation

In Table 4 , evaluating contrast-related procedures against NDRLs , 91.8 % ( 191 / 208 ) passed with contrast and 81.5 %

Table 3 . Percentage change in radiation dose parameters for patients undergoing CT scans post-NDRLs implementation .

Parameters

( 677 / 831 ) without contrast , yielding an overall pass rate of 83.5 % ( 868 / 1039 ). CTDIvol failures were 2.9 % ( 6 / 208 ) with contrast and 4.9 % ( 41 / 831 ) without contrast ; DLP failures were 1.9 % ( 4 / 208 ) with contrast and 4.4 % ( 20 / 831 ) without contrast . Also , 3.4 % ( 7 / 208 ) of procedures with contrast and 11.2 % ( 93 / 831 ) without contrast failed both CTDIvol and DLP , resulting in a combined failure rate of 9.6 % ( 100 / 1039 ).

3.5 Changes in patient effective dose

CT contrast

Table 4 . Pass / fail distribution of contrast-related procedures based on NDRLs .

Pass / fail level

Without contrast N = 831

With contrast N = 208

Total

Figure 1 represents the results of the ED before and after implementing NDRLs . Prior to introducing NDRLs , the ED for non-contrast CT scans was 12.37 ± 5.25 mSv , and for contrast scans was 9.6 ± 4.61 mSv . After the implementation of NDRLs , there were changes in the ED : Among adults , the ED for non-contrast CT scans showed a small decline of 2.43 % to 12.07 ± 4.99 mSv , and for contrast scans , a more pronounced reduction of 6.77 % to 8.95 ± 4.44 mSv . There were no statistically significant different ( p > 0.05 ).