EuroSafe Imaging 2020
Performed at one institution, Observational, Prospective, Dosimetric comparison, Radiation safety, Dosimetry, Comparative studies, Image manipulation / Reconstruction, CT-Angiography, Radioprotection / Radiation dose, Cardiac, Action 4 - Dose management systems
F. EL HEDHILI, W. Frikha, S. Boukriba, A. grich, Y. ben abdeladhim, H. Mizouni
Description of activity and work performed
This was a study conducted with a 128-detector row CT unit, over a 6-month period and including two groups of patients.
- Groupe 1: 25 patients with a routine retrospectively gated helical CT technique.
- Groupe 2: 25 patients with prospectively gated tranverse coronary CT angiography as they match our inclusion criteria: Herat rate < 65bpm and observed rate fluctuation < 10bpm.
The radiation dose estimates were expressed by using Fig. 3 :
- CT dose index in Grays.
- Dose length product (DLP) in mGy.cm
- Effective dose in ms.
For each patient in each group, we have noted the values of the product dose lenght (DLP):
- Projected DLP provieded by the CT in pre-acquisition.
- Effective DLP recieved by the patient displayed in post acquisition.
Then we calculated and compared the corresponding values projected DLP versus effective DLP, and we evaluted the image quality according to a four point score scale Fig. 4 :
||Excellent image quality (continuous ship, no stair artifact)
||Good image quality (discreet blur, minimal motion artifact)
||Medium quality (notable blur, blurred vessel, less than 25% of stair atifact)
||Poor image quality (insufficient vessel delimitation, massive stair artifact)
Our study results were:
- For groupe 1 (with a retrospectively helicale gated technique)
||830,7 [154- 1349]
|Effective dose (mSv)
||4,43 [1,24- 6,52]
||14,12 [2,6 - 21,8]
This shows that there is a theoretical increase in the radiation dose on average of 68,6% between the two techniques.
- For groupe 2 (with a prospectively transverse gated technique)
||822 [480 - 1248]
||324,8 [188 - 465]
|Effective dose (mSv)
||13,967 [8,16 - 21,2]
||5,52 [3,19 - 12,1]
This shows that there is a theoretical decrease in the radiation dose on average of 60,5% between the two techniques.
- The average effective dose of radiation per examination in the first group was 14,12mSv [2,6 -21,8] and the average effective dose in the second groupe was 5,52mSv [3,19-12,1]: This reduction of the effective dose represents an average of 60,9% of the dose with the prospectively transverse technique compared with retrospectively helical technique Fig. 5
- Regarding to the quality image, the percentage of asessable coronary artery segments was up to 98% in both groups. Only 6% of the cardiac segment were non evaluable (image quality score > 3) in the prospectively gated group and 4,5% in the retrospectively gated group.