Dosimetric comparison, Radiation safety, Dosimetry, CT, Radioprotection / Radiation dose, Radiation physics
E. Lilla, E. Balázs, C. Sokvári, Z. Dankó, L. Urbán, P. Bágyi, L. Balkay; Debrecen/HU
Methods and materials
Abdominal CT scans were performed on 655,
451 and 422 patients with GE LightSpeed VCT (CT1),
GE BrightSpeed S (CT2) and Siemens SOMATOM Definition AS (CT3),
For each scanner the AEC at the abdominal protocol was slightly modified compared to the manufacturer default values based on the opinion of an experienced medical team including radiologist,
medical physicist and radiographer.
Circular ROIs with an area of 150 mm2 were manually drawn on unenhanced single,
5 mm slice thickness,
axial slices in Jivex Dicom Viewer to obtain the mean and standard deviation (SD) of Hounsfield values in the ROI of the liver,
paraspinal muscle and subcutaneous adipose tissue for each scan .
ROI of the hepar was drawn on intact tissue in each case.
We tried to avoid the calcic parts of the aorta,
when putting the ROI there.
The ROI of the fat was placed on the ventral subcutaneous adipose tissue therefore we had to sort out patients with enough fat.
At our Radiology Department a new program was introduced which can automatically and accurately estimate the effective dose.
The EffDose values were calculated based on DLP,
the patient weight and body part investigated.
The 1/(SD^2 *EffDose) as a figure of merit (FOM) was also calculated.
The DLPs of the patient investigations were measured in mGy*cm for each CT series and device and these information along with the associated parameters (protocol name; patient name,
ID and weight) were collected from the last “dose report” CT series of the patient study.
Each dose report dicom file was sent automatically to a dedicated PACS server and an appropriate algorithm calculated the Effdose data after receiving the dicom file.
In the end,
all data were stored into a MS SQL server.
Any additional data evaluation and analysis were performed by MS Access and Excel applications connected to the SQL server.