Our study discovered a wide range of effective radiation doses associated with routine cardiovascular diagnostic procedures. The radiation dose for diagnostic ICA was significantly higher, whereas the dose for CCTA was considerably lower. We also uncovered CCTA-related trends in the mean effective radiation dose and a relationship between radiation dose and certain clinical factors. There is a gross lack of information on radiation doses to patients in most Asian countries and the absence of reports from Thailand on this issue.
To our knowledge, the present study is the first investigation of comparing the patient radiation dose during various diagnostic cardiac procedures in Thailand. We hope it may stimulate interest in the area to benefit both patients and staff.
In Northeastern Thailand, this is the first report of radiation dose from diagnosis ICA utilizing the two biplane angiocardiographic devices (double C-arc). The results of this study will promote radiation dose optimization and benefits in both patients and staff.
We have previously reported on the effective radiation dose associated with CCTA performed in 2010 in a single-center experience demonstrated the effective whole-body dose of CCTA ranged from 2.8 to 11.5 mSv depended on different dose-saving techniques and heart rates. The mean effective dose is 7.15 ± 3.4 mSv. For patients in the prospective ECG-triggering (PT) group, the mean DLP was 184 ± 66 mGy.cm, resulting in an effective radiation dose per examination of 3.1 ± 1.1 mSv. In the retrospective (RG) group, the mean DLP was 501 ± 198 mGy cm, resulting in an effective radiation dose per examination of 8.5 ± 3.4 mSv. Compared to the present study, we documented a significant decrease in radiation dose by CCTA over time and identified the correlation of a higher radiation dose. The radiation exposure from CCTA has been considerably reduced over the last ten years by almost 2.5 folds. The mean radiation dose from the newer generation CT used in 2019 was significantly lower than that of the single-source CT in 2010, p < 0.0001. In 2010, the median effective dose for coronary CTA was 7.15 ± 3.4 mSv. Still, by 2019, it has dropped to 2.88 ± 0.85 mSv, resulting in a 59.7% reduction in radiation exposure or over 2.5 times reduction in the effective dose (p < 0.0001).
Notably, the number of non-diagnostic coronary CTAs did not rise over the study period, remaining below 3% in 2010 and 2019. As the number of detector slices increases and with faster gantry rotation speeds, the temporal and spatial resolutions improve cardiac imaging, consistent with the prior study by Liang et al.  that coronary CTA performed on dual-source CT results in better image quality lower radiation dose than single-slice CT.
On this concept, ionizing radiation procedures should be conducted with the “as low as reasonably achievable” philosophy in consideration, and clinicians ordering and conducting cardiac imaging diagnostic tests should be knowledgeable with the associated radiation doses and strategies for reducing them. The mean effective radiation dose we discovered for each exam corresponds with previous studies with the same dual-source CT scanner [14, 15]. Kosmala et al.  studied the radiation dose of CCTA with a third-generation dual-source scanner in a real-world patient population and demonstrated the median effective dose was 1.32 mSv for prospective sequence and 4.77 mSv for retrospective sequence.
Furthermore, we evaluated certain variables that influence the effective radiation dose delivered by these exams. Obese individuals received considerably greater mean effective radiation doses in all the exams investigated. This was especially true of CCTA and ICA. For CCTA, the effective radiation dose was correlated with higher weight, BMI, and height, demonstrated by another study . For ICA, the effective radiation dose correlated with higher BMI and weight, in line with published data .
There are some limitations in the present study. Firstly, the current study is retrospective, single-center experience; hence, further prospective study with larger recruited patients should be considered.
Secondly, because of several technical advancements, the CCTA has significantly reduced radiation dose, which can currently be reached at the submillisievert level.
It’s important to remember that ICA has been following these developments, which were not included in this study. Because of decreased frame rates and magnification, appropriate collimation, and software solutions that interpolate virtual images between frames, ICA radiation exposure has been significantly reduced in the contemporary catheterization laboratory during the last decade.
Finally, the ICA registry’s higher radiation dose was also correlated to a higher number of positive and complexity of coronary artery disease. However, we did not analyze this. We can assume that the complexity of conditions needed more cine angiograms of the coronary arteries, with a consequent increase in the radiation dose used [18, 19].