Radiation Dose and Image Quality in Neuroangiography: Effects of Increased Tube Voltage, Added X-Ray Filtration and Antiscatter Grid Removal

Abstract

During endovascular treatment the patient may be subject to fluoroscopy for long periods as well as multiple x-ray exposures. The radiation dose to the patient can be considerable, and cause local deterministic effects such as alopecia or even skin burn. The potential carcinogenic effects should also be noted, being especially important in the paediatric population. We measured radiation doses to patients and personnel during neuroendovascular procedures and diagnostic neuroangiography. We also tried to reduce the radiation dose to the patient utilising increased tube voltage, additional primary X-ray filtration and by removing the antiscatter grid in front of the image intensifier, employing air gap technique. We investigated radiation doses to patient and personnel during neuroangiographic procedures and optimized the examination technique with regard to radiation dose with maintained image quality. Radiation exposure to patients and personnel was measured with thermoluminescent dosimeters and permanently mounted KermaDose-Area-Product meters in front of the X-ray tubes during 13 cerebral angiographies and six neuroendovascular procedures. We performed experiments with radiation dose measurements and evaluation of image quality with 80 and 90 kV tube voltage during image acquisition and 75 and 85 kV during fluoroscopy, as well as with different primary X-ray filtration. Images from patient studies acquired with the original grid in front of the image intensifier were compared with images from patient studies acquired with the grid removed and air gap technique (30 cm). Images from patient studies acquired with the original examination technique were compared to images from patient studies acquired with increased x-ray tube voltage, increased x-ray filtering and with the antiscatter grid removed using an airgap as scatter reduction method. Radiation exposure to personnel was very low using standard protective devices. Measurable doses were recorded only on the hands and forehead of the neuroradiologist. Maximum entrance skin dose was about 1 Gy on the side of the patientspatient's forehead during an endovascular procedure. Increasing the tube voltage from 75 to 85 – 85 and 90 kV, exchanging the original 0.5 mm aluminium primary filtration for 0.2 mm copper and removing the antiscatter grid allowed us to reduce entrance skin dose to the patient by 70% with unchanged or slightly improved image quality.