Both departments regularly record all dose parameters and fluoroscopy time.
For department A, with already implemented follow-up procedure since 2014, 0.8 % (2 of 256) of all patients exceeded at least one of the trigger levels for unit I and 5.6 % (20 of 358) for unit II, compared to 11 % (32 out of 292) in the department without implemented follow-up procedure (B, unit I). For further analysis of the study results and comparison between the departments and the angiography units, Mann-Whitney U test was applied, due to the non-normality of the data.
Comparing A-I (N= 256) and B-I (N= 292), the analysis showed statistically significant difference (U=33486.000, p>0.05) in kerma-area product (KAP) and (U=23197.000, p>0.05) cumulative dose at IRP (CD) distribution. B-I had larger than A-I mean rank for both KAP and CD values: respectively (287.82) vs (259.30) for KAP and 319.06 vs 218.55 for CD (see fig. 1). The results from the analysis showed significant difference between the used fluoroscopy time and number of acquired series and images. The median values and their ranges were respectively 4.7 (0.3-78.6) min, 13 (3-57) series and 703 (129-4316) images for unit A-I and 12.2 (1-105) min, 25 (7-513) series and 1939 (105-26376) images for unit B-I.
The results from the analysis of the comparison between B-I (N= 292) and A-II (N= 354) does not confirm statistically significant difference (U=47728.000, p<0.05) in KAP and (U=53118.000, p<0.05) CD distribution (see fig. 2). Contrary, the results from the analysis showed significant difference between the used fluoroscopy time and number of acquired series and images. The median values and their ranges were respectively 12.2 (1-105) min, 25 (7-513) series and 1939 (105-26376) images for unit B-I and 4.1 (0.3-52.3) min, 13 (2-78) series and 728 (2-6940) images for unit A-II.
Comparing A-I (N= 256) and A-II (N= 354), the analysis shows that the distribution of KAP is similar (U=46574.500, p>0.05) but CD distribution is different (U=62483.000, p<0.05) (see fig. 3). The results from the analysis showed no significant difference between the used fluoroscopy time and number of acquired series and images. The median values and their ranges were respectively 4.7 (0.3-78.6) min, 13 (3-57) series and 703 (129-4316) images for unit A-I and 4.1 (0.3-52.3) min, 13 (2-78) series and 728 (2-6940) images for unit A-II.
The distribution of the data for KAP and CD values for all three angiography units is shown on fig. 4. An interesting trend could be seen for unit B-I: three different types of work could be distinguished. Such a trend is not observed for the units in Department A, where a team without any personnel changes of the interventional cardiologists is working for the last 6 years.
Procedures with higher complexity are performed with higher frequency in Department A, because the department is situated in a hospital dedicated to cardiology and endovascular treatment of patients. The most complex procedures are performed on unit A-II: different aortic procedures, TAVIs, EVARs, extrathoracic procedures, peripheral angiography, diagnosis of complex congenital malformations and others. The reason is in the additional technical and software features of this particular angiography unit. For example, unit A-II has road mapping feature and digital subtraction angiography (DSA), facilitating selective catheterization and also the size of the image detector is bigger. When it is used, DSA leads to increased patient exposure, which is one of the possible explanations about the higher doses for A-II compared to A-I for similar fluoroscopy times and number of acquired series and images.
No skin reaction or skin injury has been reported from both departments for the surveyed period.
The integration of follow-up system in Department A into the clinical workflow for the last 6 years resulted in a constant percentage of followed-up patients per months, lower distribution of high dose procedures and procedures with prolonged fluoroscopy time, compared to Department B. A recommendation was given for smaller number of acquired series and images for unit B-I. Some of the archived DSA or acquisition series could be replaced with archived fluoroscopy runs.