Radiation Dose to Patients and Radiologists During Transcatheter Arterial Embolization: Comparison of a Digital Flat-Panel System and Conventional Unit

Percutaneous Glycerol Rhizotomy for Trigeminal Neuralgia Using a Single-Plane, Flat Panel Detector Angiography System: Technical Note

Percutaneous treatments for trigeminal neuralgia (TN) including glycerol rhizotomy (GR), radiofrequency thermocoagulation (RT), and balloon compression (BC) are effective for patients with medical comorbidities and risk factors of microvascular decompression (MVD). These procedures are usually performed under fluoroscopy. Surgeons advance the needle to the trigeminal plexus through the foramen ovale while observing landmarks of fluoroscopic images; however, it is sometimes difficult to appropriately place the needle tip in Meckel's cave. We present the technical details of percutaneous GR using a single-plane, flat panel detector angiography system to check the needle positioning. When the needle tip may be located near the trigeminal cistern, three-dimensional (3-D) bone images are taken with cone-beam computed tomography (CT). These images clearly show the position of the needle tip in Meckel's cave. If it is difficult to place it through the foramen ovale, surgeons perform cone beam CT to observe the actual position of the needle tip at the skull base. After confirming the positional relation between the needle tip and foramen ovale, surgeons can advance it in the precise direction. In 10 procedures, we could place the nerve-block needle in about 14.5 minutes on average without complications. We think that our method is simple and convenient for percutaneous treatments for TN, and it may be helpful for surgeons to perform such treatments.

Radiation Exposure in Transjugular Intrahepatic Portosystemic Shunt Creation

PURPOSE

Transjugular intrahepatic portosystemic shunt (TIPS) creation is considered as being one of the most complex procedures in abdominal interventional radiology. Our aim was twofold: quantification of TIPS-related patient radiation exposure in our center and identification of factors leading to reduced radiation exposure.

MATERIALS AND METHODS

Three hundred and forty seven consecutive patients underwent TIPS in our center between 2007 and 2014. Three main procedure categories were identified: Group I (n = 88)-fluoroscopic-guided portal vein targeting, procedure done in an image intensifier-based angiographic system (IIDS); Group II (n = 48)--ultrasound-guided portal vein puncture, procedure done in an IIDS; and Group III (n = 211)--ultrasound-guided portal vein puncture, procedure done in a flat panel detector-based system (FPDS). Radiation exposure (dose-area product [DAP], in Gy cm(2) and fluoroscopy time [FT] in minutes) was retrospectively analyzed.

RESULTS

DAP was significantly higher in Group I (mean ± SD 360 ± 298; median 287; 75th percentile 389 Gy cm(2)) as compared to Group II (217 ± 130; 178; 276 Gy cm(2); p = 0.002) and Group III (129 ± 117; 70; 150 Gy cm(2) p < 0.001). The difference in DAP between Groups II and III was also significant (p < 0.001). Group I had significantly longer FT (25.78 ± 13.52 min) as compared to Group II (20.45 ± 10.87 min; p = 0.02) and Group III (19.76 ± 13.34; p < 0.001). FT was not significantly different between Groups II and III (p = 0.73).

CONCLUSIONS

Real-time ultrasound-guided targeting of the portal venous system during TIPS creation results in a significantly lower radiation exposure and reduced FT. Further reduction in radiation exposure can be achieved through the use of modern angiographic units with FPDS.

Comparison between radiation exposure levels using an image intensifier and a flat-panel detector-based system in image-guided central venous catheter placement in children weighing less than 10 kg

BACKGROUND

Ultrasound-guided central venous puncture and fluoroscopic guidance during central venous catheter (CVC) positioning optimizes technical success and lowers the complication rates in children, and is therefore considered standard practice.

OBJECTIVE

The purpose of this study was to compare the radiation exposure levels recorded during CVC placement in children weighing less than 10 kg in procedures performed using an image intensifier-based angiographic system (IIDS) to those performed in a flat-panel detector-based interventional suite (FPDS).

MATERIALS AND METHODS

A retrospective review of 96 image-guided CVC placements, between January 2008 and October 2013, in 49 children weighing less than 10 kg was performed. Mean age was 8.2 ± 4.4 months (range: 1-22 months). Mean weight was 7.1 ± 2.7 kg (range: 2.5-9.8 kg). The procedures were classified into two categories: non-tunneled and tunneled CVC placement.

RESULTS

Thirty-five procedures were performed with the IIDS (21 non-tunneled CVC, 14 tunneled CVC); 61 procedures were performed with the FPDS (47 non-tunneled CVC, 14 tunneled CVC). For non-tunneled CVC, mean DAP was 113.5 ± 126.7 cGy cm(2) with the IIDS and 15.9 ± 44.6 cGy · cm(2) with the FPDS (P < 0.001). For tunneled CVC, mean DAP was 84.6 ± 81.2 cGy · cm(2) with the IIDS and 37.1 ± 33.5 cGy cm(2) with the FPDS (P = 0.02).

CONCLUSION

The use of flat-panel angiographic equipment reduces radiation exposure in small children undergoing image-guided CVC placement.

Comparing ovarian radiation doses in flat-panel and conventional angiography during uterine artery embolization: a randomized clinical trial

Background

Uterine artery embolization (UAE) is a minimally invasive procedure performed under fluoroscopy for the treatment of uterine fibroids and accompanied by radiation exposure.

Objectives

To compare ovarian radiation doses during uterine artery embolization (UAE) in patients using conventional digital subtraction angiography (DSA) with those using digital flat-panel technology.

Patients and Methods

Thirty women who were candidates for UAE were randomly enrolled for one of the two angiographic systems. Ovarian doses were calculated according to in-vitro phantom study results using entrance and exit doses and were compared between the two groups.

Results

The mean right entrance dose was 1586±1221 mGy in the conventional and 522.3±400.1 mGy in the flat panel group (P=0.005). These figures were 1470±1170 mGy and 456±396 mGy, respectively for the left side (P=0.006). The mean right exit dose was 18.8±12.3 for the conventional and 9.4±6.4 mGy for the flat panel group (P=0.013). These figures were 16.7±11.3 and 10.2±7.2 mGy, respectively for the left side (P=0.06). The mean right ovarian dose was 139.9±92 in the conventional and 23.6±16.2 mGy in the flat panel group (P<0.0001). These figures were 101.7±77.6 and 24.6±16.9 mGy, respectively for the left side (P=0.002).

Conclusion

Flat panel system can significantly reduce the ovarian radiation dose during UAE compared with conventional DSA.

Radiation exposure in biliary procedures performed to manage anastomotic strictures in pediatric liver transplant recipients: comparison between radiation exposure levels using an image intensifier and a flat-panel detector-based system

PURPOSE

The aim of this study was to estimate radiation exposure in pediatric liver transplants recipients who underwent biliary interventional procedures and to compare radiation exposure levels between biliary interventional procedures performed using an image intensifier-based angiographic system (IIDS) and a flat panel detector-based interventional system (FPDS).

MATERIALS AND METHODS

We enrolled 34 consecutive pediatric liver transplant recipients with biliary strictures between January 2008 and March 2013 with a total of 170 image-guided procedures. The dose-area product (DAP) and fluoroscopy time was recorded for each procedure. The mean age was 61 months (range 4-192), and mean weight was 17 kg (range 4-41). The procedures were classified into three categories: percutaneous transhepatic cholangiography and biliary catheter placement (n = 40); cholangiography and balloon dilatation (n = 55); and cholangiography and biliary catheter change or removal (n = 75). Ninety-two procedures were performed using an IIDS. Seventy-eight procedures performed after July 2010 were performed using an FPDS. The difference in DAP between the two angiographic systems was compared using Wilcoxon rank-sum test and a multiple linear regression model.

RESULTS

Mean DAP in the three categories was significantly greater in the group of procedures performed using the IIDS compared with those performed using the FPDS. Statistical analysis showed a p value = 0.001 for the PTBD group, p = 0.0002 for the cholangiogram and balloon dilatation group, and p = 0.00001 for the group with cholangiogram and biliary catheter change or removal.

CONCLUSION

In our selected cohort of patients, the use of an FPDS decreases radiation exposure.

SCAI consensus document on occupational radiation exposure to the pregnant cardiologist and technical personnel

Concerns regarding radiation exposure and its effects during pregnancy are often quoted as an important barrier preventing many women from pursuing a career in Interventional Cardiology. Finding the true risk of radiation exposure from performing cardiac catheterisation procedures can be challenging and guidelines for pregnancy exposure have been inadequate. The Women in Innovations group of Cardiologists with endorsement of the Society for Cardiovascular Angiography and Interventions aim to provide guidance in this publication by describing the risk of radiation exposure to pregnant physicians and cardiac catheterisation personnel, to educate on appropriate radiation monitoring and to encourage mechanisms to reduce radiation exposure. Current data do not suggest a significant increased risk to the foetus of pregnant women in the cardiac catheterisation laboratory and thus do not justify precluding pregnant physicians from performing procedures in the cardiac catheterisation laboratory. However, radiation exposure amongst pregnant physicians should be properly monitored and adequate radiation safety measures are still warranted.

A survey of radiation dose to patients and operators during radiofrequency ablation using computed tomography

Computed tomography (CT) fluoroscopy is able to give real time images to a physician undertaking minimally invasive procedures such as biopsies, percutaneous drainage, and radio frequency ablation (RFA). Both operators executing the procedure and patients too, are thus at risk of radiation exposure during a CT fluoroscopy.

This study focuses on the radiation exposure present during a series of radio frequency ablation (RFA) procedures, and used Gafchromic film (Type XR-QA; International Specialty Products, USA) and thermoluminescent dosimeters (TLD-100H; Bicron, USA) to measure the radiation received by patients undergoing treatment, and also operators subject to scatter radiation.

The voltage was held constant at 120 kVp and the current 70mA, with 5mm thickness. The duration of irradiation was between 150-638 seconds.

Ultimately, from a sample of 30 liver that have undergone RFA, the study revealed that the operator received the highest dose at the hands, which was followed by the eyes and thyroid, while secondary staff dosage was moderately uniform across all parts of the body that were measured.

Myelography using flat panel volumetric computed tomography: a comparative study in patients with lumbar spinal stenosis

STUDY DESIGN

The technical feasibility of flat panel volumetric computed tomography (FPVCT) for lumbar myelographic imaging was evaluated in 20 patients and compared with multislice computed tomography (MSCT).

OBJECTIVE

The purpose of this study was to determine the feasibility and sensitivity of FPVCT for myelographic imaging in lumbar spinal stenosis.

SUMMARY AND BACKGROUND DATA

In the diagnosis of spinal stenosis, myelography and myelo-computed tomography (PCT) have been performed routinely for nearly 30 years. Rotational angiography is a new technique initially developed to visualize vessels but also allowing multiplanar reconstructed (MPR) CT images. The spatial resolution of FPCVT is even higher than in current MSCT. To date, this technique has not been evaluated for use in myelography.

METHODS

In 20 patients referred for CT for evaluation of low back pain, lumbar myelography was performed on a biplane angiography system equipped with flat panel detectors. FPVCT was provided from a volume data set out of a rotational acquisition and compared with MSCT performed on a 4-slice CT scanner. Hereby, for a total of 100 disc levels (range from L1-L2 to L5-S1), the narrowest dural cross-sectional diameter (D-CSD) and the dural cross-sectional area (D-CSA) referred to MSCT and FPVCT were calculated.

RESULTS

Mean D-CSD and C-CSA for all disc levels as measured by MSCT was 9.26 +/- 3.0 mm and 63.2 +/- 10.8 mm, respectively. Compared with D-CSD and C-CSA measured by FPVCT, there was no statistically significant difference (9.48 +/- 2.9 mm and 64.7 +/- 11.2 mm, respectively; P > 0.89). The most pronounced lumbar spinal stenosis was seen on L4/5 level with D-CSD of 6.6 +/- 3.6 mm and 6.8 +/- 3.2 mm and D-CSA of 53.7 +/- 14.7 mm and 55.0 +/- 14.3 mm, respectively.

CONCLUSION

In all patients, the diagnostic quality of the reconstructed FPVCT slice images is comparable to those acquired by MSCT. Using FPVCT, radiographic myelography and postmyelographic computed tomography can be performed with less radiation in a single session at the same imaging system.

Use of 120 kilovolt tube potential for digital subtraction angiography and fluoroscopy in an image-intensifier angiographic system: decrease of skin dose in transarterial chemoembolization therapy for hepatocellular carcinoma

In an image-intensifier angiographic system, the tube potential is commonly regulated in ranges from 75 to 90 kV for digital subtraction angiography (DSA) and fluoroscopy in transarterial chemoembolization therapy (TACE) for hepatocellular carcinoma. The purpose of this study was to investigate whether or not a 120-kV tube potential could be used for DSA and fluoroscopy in TACE to decrease the skin dose. Forty-three patients administered TACE were randomly allocated into two groups: TACE was performed using standard-kilovoltage (75- to 90-kV) DSA and fluoroscopy modes (group A; n = 20) or using high-kilovoltage (120-kV) modes (group B; n = 23). The peak skin dose was compared between the groups. One case in group A was excluded from the study because the HCC nodule was not depicted on DSA. The peak skin dose (mGy) for group A was 383.6 +/- 176.5 and that for group B was 265.1 +/- 145.1. The peak skin dose was decreased by 31% in the 120-kV mode, a statistically significant difference (t-test, p = 0.022). We conclude that the use of 120 kV tube potential for DSA and fluoroscopy may be one option for performing TACE while decreasing the skin dose.

Advances in Digital Radiography: Physical Principles and System Overview

During the past two decades, digital radiography has supplanted screen-film radiography in many radiology departments. Today, manufacturers provide a variety of digital imaging solutions based on various detector and readout technologies. Digital detectors allow implementation of a fully digital picture archiving and communication system, in which images are stored digitally and are available anytime. Image distribution in hospitals can now be achieved electronically by means of web-based technology with no risk of losing images. Other advantages of digital radiography include higher patient throughput, increased dose efficiency, and the greater dynamic range of digital detectors with possible reduction of radiation exposure to the patient. The future of radiography will be digital, and it behooves radiologists to be familiar with the technical principles, image quality criteria, and radiation exposure issues associated with the various digital radiography systems that are currently available.

Angiographic Computed Tomography is Comparable to Multislice Computed Tomography in Lumbar Myelographic Imaging

We evaluated the feasibility of angiographic computed tomography (ACT) for diagnostic imaging in a patient with degenerative lumbar spine disease. ACT provides a volume data set out of a rotational acquisition with a c-arm-mounted flat-panel detector. Using this technique, radiographic myelography and myelographic computed tomography can be performed in a single session at the same imaging system. The quality of the reconstructed ACT slice images is comparable to those acquired by postmyelographic computed tomography.