Methods
A retrospective cohort study was performed at Cork University Hospital,
in Cork,
Ireland.
Radiation dose was measured using Dose Area Product (DAP) measured in mGy.cm2.
Data collection was carried out on the Picture Archiving and Communication System (Impax 6.5.3; Agfa Healthcare,
Morstel,
Belgium) and dose tracking software (DoseWatch,
GE,
Milwaukee,
WI).
Cases were excluded if dose level data was missing.
Additional variable data on aneurysm coiling procedures was provided by a prospectively gathered patient procedure database continuously maintained by a consultant neurointerventional radiologist.
Statistical analysis was performed using IBM SPSS software version 23.
Two hundred and sixty-four patients who underwent neurointerventional procedures at Cork University Hospital between November 2014 and November 2015 were selected.
thirty-two cases were excluded due to insufficient data.
twenty-two of these cases were diagnostic; The remaining ten were therapeutic.
Four neurointerventional procedures were studied: (1) four vessel angiogram,
(2) aneurysm coiling,
(3) arteriovenous malformation embolization,
and (4) stroke thrombolysis/thrombectomy.
One hundred and nine aneurysm coiling procedures were selected for the second objective,
including cases selected for objective 1.
the remaining cases were collected from the end period of objective 1 (November 2015) to September 2016.
Results: Objective 1
Procedure type
Of the two-hundred and sixty-four procedures selected,
one hundred and eighty nine were four-vessel angiograms,
fifty-nine were aneurysm coiling procedures,
ten were stroke thrombolysis/thrombectomy,
and six were arteriovenous malformation embolization.
Patient demographic
Sixty-one percent of patients were female and thirty-nine percent were male.
Procedures distinguished by sex differed substantially.
The number of aneurysm coiling procedures performed on women was 3.7 times the number performed on men.
Overall,
women were more likely to undergo both diagnostic and therapeutic procedures.
Patient age was categorized into groups of equal distribution and numbered for data analysis.
Patients aged 46-55 (group 4) had the highest number of therapeutic procedures performed.
Patients aged 46-65 (groups 4 and 5) shared the highest number of overall procedures performed.
Radiation dose
The median radiation DAP for diagnostic angiography (four-vessel angiogram) was 73.7 Gy.cm2 (DAP range - 94-1412).
The remaining procedures were therapeutic.
The median DAP for aneurysm coiling was 104.9 Gy.cm2 (DAP range - 42-2000).
The median DAP for arteriovenous malformation embolization was 259.4 Gy.cm2 (DAP range - 74-3300),
the median DAP for stroke thrombolysis/thrombectomy was 87 Gy.cm2 (DAP range - 37-191).
The Health Services Executive (Irish health service) have published dose reference levels (75th percentile DAP) for other interventional procedures.
Other interventional procedures generally have lower DAP.
For example,
the DRL for a barium enema is 47 Gy.Cm2,
however,
the DRL for a transjugular intrahepatic portosystemic shunt procedure (TIPS),
a more complicated procedure,
and more comparable to a challenging embolisation is referenced at 144.4 Gy.cm2 [2][3].
A number of outliers were found for both aneurysm coiling and four-vessel angiogram groups.
The patient case files were reviewed on PACS to determine possible causes for the increased doses.
Five of the six four-vessel angiogram outlier cases had arteriovenous malformations which required addiation imaging projections and more contrast studies than normal.
Three of the five-aneurysm coiling procedure outliers were posterior circulation aneurysm with/without anterior circulation aneurysms.
The two remaining cases were anterior circulation aneurysms developed complications,
such as coil herniation and vasospasm.
Results: Objective 2
Aneurysm coiling variables were analysed to determined variables that had a significant effect on radiation dose to the patient.
Overall,
nine variables were found to have a significant effect ( Table 3 ).
These variables were then analysed further to determine what vairable had the single biggest effect on radiation dose.
Overall,
aneurysm location (posterior circulation vs.
anterior circulation) was found to have the single biggest effect on radiation dose (p=.004,
see Table 4 ).