Radiation dose reduction with frame rate conversion in X-ray fluoroscopic imaging systems with flat panel detector: basic study and clinical retrospective analysis

How should radiation exposure be handled in fluoroscopy-guided endoscopic procedures in the field of gastroenterology?

Fluoroscopy-guided endoscopic procedures (FGEPs) are rapidly gaining popularity in the field of gastroenterology. Radiation is a well-known health hazard. Gastroenterologists who perform FGEPs are required to protect themselves, patients, as well as nurses and radiologists engaged in examinations from radiation exposure. To achieve this, all gastroenterologists must first understand and adhere to the International Commission on Radiological Protection Publication. In particular, it is necessary to understand the three principles of radiation protection (Justification, Optimization, and Dose Limits), the As Low As Reasonably Achievable principle, and the Diagnostic Reference Levels (DRLs) according to them. This review will mainly explain the three principles of radiation exposure protection, DRLs, and occupational radiological protection in interventional procedures while introducing related findings. Gastroenterologists must gain knowledge of radiation exposure protection and keep it updated.

Evaluating the accuracy of simplified VCUG in comparison with traditional VCUG for diagnosis of urinary-reflux in children: Radiation dose reduction

INTRODUCTION

Voiding cystourethrogram (VCUG) is an imaging technique for diagnosing urinary-reflux. VCUG requires X-ray exposure, increasing the risk of malignancies induced by ionizing radiation, especially in children. Considering the importance of early diagnosis of urinary-reflux using VCUG to prevent kidney complications and the significance of reducing the radiation dose during this imaging, this study intends to reduce the imaging views of VCUG and evaluate the urinary-reflux, using a reduced number of images.

MATERIAL AND METHODS

Children referred to a University hospital who underwent VCUG participated in this study. The routine VCUG procedure contained five images. Two images of full-bladder and post-void of each patient were considered a simplified procedure and were evaluated by two radiologists to determine reflux and its grade. The sensitivity and specificity of simplified VCUG were determined.

RESULTS

182 patients with a mean age of 5.36±4.95 years old participated in this study. There were 90% and 82% agreement between routine and simplified VCUG results in the left and right kidneys. The simplified VCUG had 87.2% and 100% sensitivity and specificity in detecting the left-side reflux, 83 .9% and 100%, to detect the right-side reflux.

CONCLUSION

The results showed that using two images instead of five can effectively diagnose and grade urinary-reflux. The simplified VCUG had a relatively good and acceptable agreement in comparison to the routine cystourethrogram. It can effectively reduce the patient's radiation dose, especially in patients who need to perform serial bladder imaging for follow-up after operation.

Digital variance angiography allows about 70% decrease of DSA-related radiation exposure in lower limb X-ray angiography

Our aim was to investigate whether the previously observed higher contrast-to-noise ratio (CNR) and better image quality of Digital Variance Angiography (DVA) - compared to Digital Subtraction Angiography (DSA) - can be used to reduce radiation exposure in lower limb X-ray angiography. This prospective study enrolled 30 peripheral artery disease patients (mean ± SD age 70 ± 8 years) undergoing diagnostic angiography. In all patients, both normal (1.2 µGy/frame; 100%) and low-dose (0.36 µGy/frame; 30%) protocols were used for the acquisition of images in three anatomical regions (abdominal, femoral, crural). The CNR of DSA and DVA images were calculated, and the visual quality was evaluated by seven specialists using a 5-grade Likert scale. For investigating non-inferiority, the difference of low-dose DVA and normal dose DSA scores (DVA30-DSA100) was analyzed. DVA produced two- to three-fold CNR and significantly higher visual score than DSA. DVA30 proved to be superior to DSA100 in the crural region (difference 0.25 ± 0.07, p < 0.001), and there was no significant difference in the femoral (− 0.08 ± 0.06, p = 0.435) and abdominal (− 0.10 ± 0.09, p = 0.350) regions. Our data show that DVA allows about 70% reduction of DSA-related radiation exposure in lower limb X-ray angiography, providing a potential new radiation protection tool for the patients and the medical staff.

Evaluation of image quality and patient exposure in fluoroscopy using a phantom: Is there any clinical relevance?

OBJECTIVE

To investigate the impact of X-ray preset acquisition protocol settings on fluoroscopy image quality (IQ) and radiation exposure.

MATERIALS & METHODS

A quality control (QC) phantom was imaged with a modern digital C-arm system, using various preset fluoroscopy protocols. IQ was assessed using human observers and in-house software for automated evaluation, based on contrast-to-noise ratios of details and their background. Patient radiation exposure was evaluated using the displayed Incident Air-Kerma and Kerma-Area Product values.

RESULTS

Protocol selection affects radiation exposure by a factor of about 3. IQ evaluation showed that acquisition protocols produce images with quite different characteristics. The visual IQ evaluation method was time consuming and cumbersome. The automated method, utilized the visual IQ evaluation results for calibration of detection thresholds. However, it failed to reproduce these results for all images and details types. In some images, digital image processing created artifacts which affected the pixel value distributions around details in a way that could be handled only by the human vision.

CONCLUSION

Manufacturers provide many preset protocols designated for specific clinical uses, which have large impact on IQ characteristics and radiation exposure. However, protocol settings' selection rationale is essentially a "black box" for the end user. Though QC phantoms are currently used for IQ evaluation, they are not appropriate for drawing firm conclusions concerning the expected performance of each protocol in clinical practice. Currently, there is no consensus on the optimum technical characteristics of preset protocols for specific procedures. More work is needed in this area.