Skin dose measurements on patients for diagnostic and interventional neuroradiology: a multicentre study

Endovascular treatment of basilar tip aneurysms in the era of endosaccular flow disruption: a comparative study

Purpose

This study aims to compare endosaccular flow disruptor (EFD) for treatment of basilar tip aneurysm (BTA) with coiling in terms of safety and efficacy.

Methods

We retrospectively reviewed patients treated with an EFD for BTAs at our institution between 2013 and 2019 to standard coiling from the same period (control group). Patient demographics, aneurysm characteristics, procedural data, complications and clinical and angiographic outcome were compared between groups.

Results

Twenty-three (56%) patients were treated with an EFD and eighteen (44%) patients were treated with coiling. Average aneurysm size was 8 mm in the EFD group and 6.9 mm in the coiling group, respectively (P = 0.2). Average fluoroscopy time, treatment DAP and air kerma were 33 min, 76 Gycm² and 1.7 Gy in the EFD group and 81 min, 152 Gycm² and 3.8 Gy in the coiling group, respectively (P < 0.001). In the EFD group, clinically relevant thromboembolic complications occurred in one patient (4%) vs. in 5 patients (28%) in the coiling group (P = 0.07). In each group, 4 patients had an unfavourable outcome at discharge (P = 0.7). Adequate occlusion rates were 96% in the EFD group and 100% and coiling group. Six (26%) patients were prescribed long-term antiplatelet therapy in the EFD group vs. eleven (61%) patients in the coiling group (P = 0.02).

Conclusion

Both treatment concepts provided similar technical success and safety. However, procedure time, radiation exposure and a need for long-term antiaggregation were lower with EFD.

ESTIMATION OF RADIATION EXPOSURE TO THE PATIENTS IN DIAGNOSTIC AND THERAPEUTIC INTERVENTIONAL PROCEDURES

The present work reports data of the radiation exposure to the patient in various diagnostic and therapeutic interventional radiological (IR) procedures. The study includes 260 diagnostic and 195 therapeutic exposure data in 455 IR procedures. All the IR procedures were performed on a biplane angiographic machine in a tertiary care hospital. The radiation exposure was estimated from dose-area product (DAP), fluoroscopy time (FT), number of fluoroscopic runs, number of images and cumulative dose (CD) value recorded during the procedure. The data reported in the present study show significant variability in DAP values in diagnostic and therapeutic IR procedures. In diagnostic procedures, the minimum median DAP value is 8.93 Gy cm2 for upper limb angiography with mean FT of 2.7 min and maximum DAP value is 108.8 Gy cm2 for inferior vena cava angiography with mean FT of 12.55 min. For therapeutic procedures, the median value of DAP ranges from 2.43 Gy cm2 for sclerotherapy with mean FT 0.65 min to 267.23 Gy cm2 for coiling of cerebral aneurysm with mean FT of 60.52 min. The DAP value for each procedure was also correlated with FT, number of fluoroscopic runs, number of images and CD. The reported DAP values in this study are within the range of earlier published results which suggest that our finding provides at least approximate applicability to other hospitals. The third quartile DAP values of the procedures having significant number of patient data (n ≥ 10) serves as provisional reference values for the optimization of procedure protocols.

Pediatric minor head trauma: do cranial CT scans change the therapeutic approach?

OBJECTIVES:

1) To verify clinical signs correlated with appropriate cranial computed tomography scan indications and changes in the therapeutic approach in pediatric minor head trauma scenarios. 2) To estimate the radiation exposure of computed tomography scans with low dose protocols in the context of trauma and the additional associated risk.

METHODS:

Investigators reviewed the medical records of all children with minor head trauma, which was defined as a Glasgow coma scale ≥13 at the time of admission to the emergency room, who underwent computed tomography scans during the years of 2013 and 2014. A change in the therapeutic approach was defined as a neurosurgical intervention performed within 30 days, hospitalization, >12 hours of observation, or neuro-specialist evaluation.

RESULTS:

Of the 1006 children evaluated, 101 showed some abnormality on head computed tomography scans, including 49 who were hospitalized, 16 who remained under observation and 36 who were dismissed. No patient underwent neurosurgery. No statistically significant relationship was observed between patient age, time between trauma and admission, or signs/symptoms related to trauma and abnormal imaging results. A statistically significant relationship between abnormal image results and a fall higher than 1.0 meter was observed (p=0.044). The mean effective dose was 2.0 mSv (0.1 to 6.8 mSv), corresponding to an estimated additional cancer risk of 0.05%.

CONCLUSION:

A computed tomography scan after minor head injury in pediatric patients did not show clinically relevant abnormalities that could lead to neurosurgical indications. Patients who fell more than 1.0 m were more likely to have changes in imaging tests, although these changes did not require neurosurgical intervention; therefore, the use of computed tomography scans may be questioned in this group. The results support the trend of more careful indications for cranial computed tomography scans for children with minor head trauma.

Patient Radiation Exposure During Diagnostic and Therapeutic Procedures for Intracranial Aneurysms: A Multicenter Study

PURPOSE

To assess patient radiation doses during cerebral angiography and embolization of intracranial aneurysms across multi-centers and propose a diagnostic reference level (DRL).

MATERIALS AND METHODS

We studied a sample of 490 diagnostic and 371 therapeutic procedures for intracranial aneurysms, which were performed at 23 hospitals in Korea in 2015. Parameters including dose-area product (DAP), cumulative air kerma (CAK), fluoroscopic time and total angiographic image frames were obtained and analyzed.

RESULTS

Total mean DAP, CAK, fluoroscopy time, and total angiographic image frames were 106.2 ± 66.4 Gy-cm(2), 697.1 ± 473.7 mGy, 9.7 ± 6.5 minutes, 241.5 ± 116.6 frames for diagnostic procedures, 218.8 ± 164.3 Gy-cm(2), 3365.7 ± 2205.8 mGy, 51.5 ± 31.1 minutes, 443.5 ± 270.7 frames for therapeutic procedures, respectively. For diagnostic procedure, the third quartiles for DRLs were 144.2 Gy-cm(2) for DAP, 921.1 mGy for CAK, 12.2 minutes for fluoroscopy times and 286.5 for number of image frames, respectively. For therapeutic procedures, the third quartiles for DRLs were 271.0 Gy-cm(2) for DAP, 4471.3 mGy for CAK, 64.7 minutes for fluoroscopy times and 567.3 for number of image frames, respectively. On average, rotational angiography was used 1.5 ± 0.7 times/session (range, 0-4; n=490) for diagnostic procedures and 1.6 ± 1.2 times/session (range, 0-4; n=368) for therapeutic procedures, respectively.

CONCLUSION

Radiation dose as measured by DAP, fluoroscopy time and image frames were lower in our patients compared to another study regarding cerebral angiography, and DAP was lower with fewer angiographic image frames for therapeutic procedures. Proposed DRLs can be used for quality assurance and patient safety in diagnostic and therapeutic procedures.

Estimates of diagnostic reference levels for pediatric peripheral and abdominal fluoroscopically guided procedures

OBJECTIVE

The objective of our study was to survey radiation dose indexes of pediatric peripheral and abdominal fluoroscopically guided procedures from which estimates of diagnostic reference levels (DRLs) can be proposed for both a standard fluoroscope and a novel fluoroscope with advanced image processing and lower radiation dose rates.

MATERIALS AND METHODS

Radiation dose structured reports were retrospectively collected for 408 clinical pediatric cases: Half of the procedures were performed with a standard imaging technology and half with a novel x-ray technology. Dose-area product (DAP), air Kerma (AK), fluoroscopy time, number of digital subtraction angiography images, and patient mass were collected to calculate and normalize radiation dose indexes for procedures completed with the standard and novel fluoroscopes.

RESULTS

The study population was composed of 180 and 175 patients who underwent procedures with the standard and novel technology, respectively. The 21 different types of pediatric peripheral and abdominal interventional procedures produced 408 total studies. Median ages, mass and body mass index, fluoroscopy time per procedure, and total number of recorded images for the standard and novel technologies were not statistically different. The area of the x-ray beams was square at the level of the patient with a dimension of 10-13 cm. The dose reduction achieved with the novel fluoroscope ranged from 18% to 51% of the dose required with the standard fluoroscope. The median DAP and AK patient dose indexes were 0.38 Gy · cm(2) and 4.00 mGy, respectively, for the novel fluoroscope.

CONCLUSION

Estimates of dose indexes of pediatric peripheral and abdominal fluoroscopically guided, clinical procedures should assist in the development of DRLs to foster management of radiation doses of pediatric patients.

Measurement of maximum skin dose in interventional radiology and cardiology and challenges in the set-up of European alert thresholds

To help operators acknowledge patient dose during interventional procedures, EURADOS WG-12 focused on measuring patient skin dose using XR-RV3 gafchromic films, thermoluminescent detector (TLD) pellets or 2D TL foils and on investigating possible correlation to the on-line dose indicators such as fluoroscopy time, Kerma-area product (KAP) and cumulative air Kerma at reference point (CK). The study aims at defining non-centre-specific European alert thresholds for skin dose in three interventional procedures: chemoembolization of the liver (CE), neuroembolization (NE) and percutaneous coronary interventions (PCI). Skin dose values of >3 Gy (ICRP threshold for skin injuries) were indeed measured in these procedures confirming the need for dose indicators that correlate with maximum skin dose (MSD). However, although MSD showed fairly good correlation with KAP and CK, several limitations were identified challenging the set-up of non-centre-specific European alert thresholds. This paper presents preliminary results of this wide European measurement campaign and focuses on the main challenges in the definition of European alert thresholds.

Patient radiation dose in diagnostic and interventional procedures for intracranial aneurysms: experience at a single center

Objective

To assess patient radiation doses during cerebral angiography and embolization of intracranial aneurysms in a large sample size from a single center.

Materials and Methods

We studied a sample of 439 diagnostic and 149 therapeutic procedures for intracranial aneurysms in 480 patients (331 females, 149 males; median age, 57 years; range, 21-88 years), which were performed in 2012 with a biplane unit. Parameters including fluoroscopic time, dose-area product (DAP), and total angiographic image frames were obtained and analyzed.

Results

Mean fluoroscopic time, total mean DAP, and total image frames were 12.6 minutes, 136.6 ± 44.8 Gy-cm², and 251 ± 49 frames for diagnostic procedures, 52.9 minutes, 226.0 ± 129.2 Gy-cm², and 241 frames for therapeutic procedures, and 52.2 minutes, 334.5 ± 184.6 Gy-cm², and 408 frames for when both procedures were performed during the same session. The third quartiles for diagnostic reference levels (DRLs) were 14.0, 61.1, and 66.1 minutes for fluoroscopy time, 154.2, 272.8, and 393.8 Gy-cm² for DAP, and 272, 276, and 535 for numbers of image frames in diagnostic, therapeutic, and both procedures in the same session, respectively. The proportions of fluoroscopy in DAP for the procedures were 11.4%, 50.5%, and 36.1%, respectively, for the three groups. The mean DAP for each 3-dimensional rotational angiographic acquisition was 19.2 ± 3.2 Gy-cm². On average, rotational angiography was used 1.4 ± 0.6 times/session (range, 1-4; n = 580).

Conclusion

Radiation dose in our study as measured by DAP, fluoroscopy time and image frames did not differ significantly from other reported DRL studies for cerebral angiography, and DAP was lower with fewer angiographic image frames for embolization. A national registry of radiation-dose data is a necessary next step to refine the dose reference level.

Brain radiation doses to patients in an interventional neuroradiology laboratory

BACKGROUND AND PURPOSE

In 2011, the International Commission on Radiologic Protection established an absorbed-dose threshold to the brain of 0.5 Gy as likely to produce cerebrovascular disease. In this paper, the authors investigated the brain doses delivered to patients during clinical neuroradiology procedures in a university hospital.

MATERIALS AND METHODS

The radiation dose delivered to the brain was investigated in 99 diagnostic and therapeutic interventional neuroradiology procedures. Brain doses were calculated in a mathematic model of an adult standard anthropomorphic phantom by using the technical and radiation dose data of an x-ray biplane system submitted to regular quality controls and calibration programs.

RESULTS

For cerebral embolizations, brain doses resulted in a maximum value of 1.7 Gy, with an average value of 500 mGy. Median and third quartile resulted in 400 and 856 mGy, respectively. For cerebral angiography, the average dose in the brain was 100 mGy.

CONCLUSIONS

This work supports the International Commission on Radiologic Protection recommendation on enhancing optimization when doses to the brain could be higher than 0.5 Gy. Radiation doses should be recorded for all patients and kept as low as reasonably achievable. For pediatric patients and young adults, an individual evaluation of brain doses could be appropriate.

Radiation dose analysis of large and giant internal carotid artery aneurysm treatment with the pipeline embolization device versus traditional coiling techniques

BACKGROUND

Flow diversion is an effective and increasingly accepted method for endovascular treatment of cerebral aneurysms. Additionally, the public has heightened concerns regarding radiation exposure from medical procedures. This study analyzes radiation dose and fluoroscopy time during treatment of large and giant proximal internal carotid artery (ICA) aneurysms with the pipeline embolization device (PED) versus traditional coiling techniques.

METHODS

Radiation dose, fluoroscopy time, and contrast dye administration were retrospectively analyzed in 55 patients undergoing endovascular treatment of aneurysms ≥ 10 mm from petrous to superior hypophyseal ICA segments. Patients were treated by either PED (37 patients) or traditional coiling techniques (18 patients). Aortic arch type and proximal ICA tortuosity were also assessed as markers of access difficulty.

RESULTS

Average radiation dose with PED treatment was 2840 ± 213 mGy and 4010 ± 708 mGy with traditional coiling techniques (p=0.048; 29% decrease with PED). Mean fluoroscopy time for PED was 56.1 ± 5.0 min and 85.9 ± 11.9 min for coiling cases (p=0.0087; 35% decrease with PED). These benefits existed despite more difficult arch anatomy and a trend towards greater proximal vessel tortuosity in PED cases. Contrast dye amounts were also reduced by 37.5% in PED cases (75 ± 6 mL) versus coiling cases (120 ± 13 mL, p=0.0008).

CONCLUSIONS

Treatment of large and giant proximal ICA aneurysms using PED requires less radiation, less fluoroscopy time, and less contrast administration than standard coiling techniques. This further demonstrates the benefits of flow diversion for treatment of these aneurysms.

Diagnostic quality and accuracy of low dose 3D-DSA protocols in the evaluation of intracranial aneurysms

BACKGROUND

3D-DSA is the 'gold standard' imaging technique for the diagnosis and characterization of intracranial aneurysms.

OBJECTIVE

To compare the image quality and accuracy of low dose 3D-DSA protocols in patients with unruptured intracranial aneurysms.

MATERIALS AND METHODS

The standard manufacturer 5 s 0.36 μGy/f protocol and one of three low dose 3D-DSA protocols (5 s 0.10 μGy/f, 5 s 0.17 μGy/f, 5 s 0.24 μGy/f) were performed in 12 patients with unruptured intracranial aneurysms. Three interventional neuroradiologists, two neurosurgeons, and two neurologists rated the image quality of all 3D reconstructions as good, acceptable, or poor. Three interventional neuroradiologists measured two dimensions of each aneurysm for all protocols. The radiation dose metric Ka,r (reference point air kerma, in mGy) was recorded for each 3D-DSA protocol.

RESULTS

The standard 5 s 0.36 μGy/f protocol earned the highest average subjective rating of 2.76, followed by the 5 s 0.24 μGy/f (2.72), and 5 s 0.17 μGy/f (2.59) protocols. The ranges of differences in aneurysm measurements between the 5 s 0.24 μGy/f protocol and the standard were <0.5 mm. The median Ka,r metrics for each protocol were as follows: 5 s 0.36 μGy/f (89.0 mGy), 5 s 0.24 μGy/f (57.7 mGy), 5 s 0.17 μGy/f (45.9 mGy), and 5 s 0.10 μGy/f (27.6 mGy).

CONCLUSIONS

Low dose 3D-DSA protocols with preserved image quality are achievable, and can help reduce exposure of patients and operators to unnecessary radiation. The 5 s 0.24 μGy/f protocol generates one-third smaller radiation dose than the standard 5 s 0.36 μGy/f protocol without compromising diagnostic image quality or accuracy.

Reducing radiation dose while maintaining diagnostic image quality of cerebral three-dimensional digital subtraction angiography: an in vivo study in swine

BACKGROUND

Three-dimensional digital subtraction angiography (3D-DSA) is a modern technique that allows for better appreciation of complex vascular lesions. This study evaluates the impact of various dose reduction strategies on 3D-DSA image quality.

METHODS

The standard manufacturer 5 s 0.36 μGy/frame setting was modified to create lower dose 3D-DSA protocols by varying the acquisition time (5 or 3 s) and/or dose per frame (0.36, 0.24, 0.17, and 0.10 μGy/f). All protocols were evaluated in three swine. Four raters measured a segment of the external carotid artery on two-dimensional multiplanar reconstruction images. The raters were also presented with three-dimensional volume rendered images from all protocols in a blinded manner and asked to choose the superior image. A full model analysis of variance with repeated measure factors was performed to compare mean differences in measurements between protocols.

RESULTS

Measurement differences between the standard and low dose protocols were not clinically significant (<0.5 mm). All raters demonstrated high inter-rater reliability. The 5 s protocols were considered as qualitatively superior to the 3 s protocols. Delivered system doses ranged from 43.8 to 6.5 mGy. The 5 s 0.10 μGy/frame protocols generated 65-68% less delivered dose compared with the 5 s 0.36 μGy/frame setting.

CONCLUSIONS

Low dose 3D-DSA protocols with preserved image quality are achievable, and can help reduce unnecessary radiation exposure to both patients and operators. The 5 s low dose protocols generated clinically acceptable and superior images compared with the 3 s protocols, suggesting a more important role for acquisition time than dose per frame to maintain image quality.

Flow diversion versus traditional aneurysm embolization strategies: analysis of fluoroscopy and procedure times

BACKGROUND AND OBJECTIVE

Flow diverters are increasingly used for treatment of complex intracranial aneurysms. The purpose of this study was to compare the pipeline embolization device (PED) and traditional embolization strategies in terms of fluoroscopy and procedure time.

MATERIAL AND METHODS

Fluoroscopy and procedure times (in minutes) were retrospectively analyzed and compared between 127 patients treated with the PED, 86 patients treated with single stage stent assisted coiling (SAC), and 16 patients treated with Onyx HD 500 at our institution. A multivariate logistic regression analysis was performed to determine independent predictors of fluoroscopy and procedure time.

RESULTS

The three groups were comparable with respect to patient age, gender, and ruptured/unruptured aneurysm status. Aneurysms treated with the PED were significantly larger than stent coiled aneurysms, and aneurysm location distribution differed significantly between the three groups. Mean fluoroscopy time was significantly increased in the SAC (55±31 min, p<0.001) and Onyx HD 500 (91±36 min, p<0.001) groups relative to the PED group (34±23 min). Likewise, mean procedure time was significantly longer in SAC (155±50 min, p<0.001) and Onyx HD 500 (176±65 min, p<0.001) patients compared with PED patients (131±36 min). In multivariate analysis, SAC/Onyx HD 500 versus PED independently predicted longer procedure and fluoroscopy times.

CONCLUSIONS

PED treatment requires significantly shorter fluoroscopy and procedure times compared with SAC and Onyx HD 500. The results of this study may be used by advocates of flow diverters as an additional argument for using this treatment modality to treat intracranial aneurysms.

High-resolution 3D X-ray imaging of intracranial nitinol stents

INTRODUCTION

To assess an optimized 3D imaging protocol for intracranial nitinol stents in 3D C-arm flat detector imaging. For this purpose, an image quality simulation and an in vitro study was carried out.

METHODS

Nitinol stents of various brands were placed inside an anthropomorphic head phantom, using iodine contrast. Experiments with objects were preceded by image quality and dose simulations. We varied X-ray imaging parameters in a commercially interventional X-ray system to set 3D image quality in the contrast-noise-sharpness space. Beam quality was varied to evaluate contrast of the stents while keeping absorbed dose below recommended values. Two detector formats were used, paired with an appropriate pixel size and X-ray focus size. Zoomed reconstructions were carried out and snapshot images acquired. High contrast spatial resolution was assessed with a CT phantom.

RESULTS

We found an optimal protocol for imaging intracranial nitinol stents. Contrast resolution was optimized for nickel-titanium-containing stents. A high spatial resolution larger than 2.1 lp/mm allows struts to be visualized. We obtained images of stents of various brands and a representative set of images is shown. Independent of the make, struts can be imaged with virtually continuous strokes. Measured absorbed doses are shown to be lower than 50 mGy Computed Tomography Dose Index (CTDI).

CONCLUSION

By balancing the modulation transfer of the imaging components and tuning the high-contrast imaging capabilities, we have shown that thin nitinol stent wires can be reconstructed with high contrast-to-noise ratio and good detail, while keeping radiation doses within recommended values. Experimental results compare well with imaging simulations.

Delayed effects of exposure to a moderate radiation dose on transcription profiles in human primary fibroblasts

Ionizing radiation (IR) is used in a wide variety of medical and nonmedical applications and poses a potential threat to human health. Knowledge of changes in gene expression in irradiated cells may be helpful for the establishment of effective paradigms for radiation protection. IR-induced DNA damage triggers a complex cascade of signal transduction. Recently, genome-wide approaches have allowed the detection of alterations in gene expression across a wide range of radiation doses. However, the delayed or long-term biological effects of mild-doses of IR remain largely unknown. The main objective of the present study was to investigate the effects of a moderate dose of gamma-rays (50 cGy) on gene expression 6 days post-irradiation. Gene expression using cDNA microarrays revealed statistically significant changes in the expression of 59 genes (FDR < 0.07), whose functions are related to cell-cycle control, protein trafficking, ubiquitin cycle, Rho-GTPAse pathway, protein phosphatase signalization, oxidoreductase control, and stress response. A set of 464 genes was also selected by a less stringent approach, and we demonstrate that this broader set of genes can efficiently distinguish the irradiated samples from the unirradiated, defining a long-term IR signature in human primary fibroblasts. Our findings support the existence of persistent responses to mild doses of IR detectable by changes in gene expression profiles. These results provide insight into delayed effects observed in human primary cells as well as the role of long-term response in neoplastic transformation. Environ.

A study of the relationship between peak skin dose and cumulative air kerma in interventional neuroradiology and cardiology

A study of peak skin doses (PSDs) during neuroradiology and cardiology interventional procedures has been carried out using Gafchromic XR-RV2 film. Use of mosaics made from squares held in cling film has allowed doses to the head to be mapped successfully. The displayed cumulative air kerma (CAK) has been calibrated in terms of cumulative entrance surface dose (CESD) and results indicate that this can provide a reliable indicator of the PSD in neuroradiology. Results linking PSD to CESD for interventional cardiology were variable, but CAK is still considered to provide the best option for use as an indicator of potential radiation-induced effects. A CESD exceeding 3 Gy is considered a suitable action level for triggering follow-up of patients in neuroradiology and cardiology for possible skin effects. Application of dose action levels defined in this way would affect 8% of neurological embolisation procedures and 5% of cardiology ablation and multiple stent procedures at the hospitals where the investigations were carried out. A close relationship was observed between CESD and dose-area product (DAP) for particular types of procedure, and DAPs of 200-300  Gy cm(2) could be used as trigger levels where CAK readings were not available. The DAP value would depend on the mean field size and would need to be determined for each application.

Cumulative radiation dose during hospitalization for aneurysmal subarachnoid hemorrhage

BACKGROUND AND PURPOSE

Radiation exposure from neurointerventional procedures and diagnostic neuroimaging can be substantial, with many recommendations offered to guide the interventionalist in the conscientious use of ionizing radiation. Patients presenting with an aneurysmal subarachnoid hemorrhage can undergo multiple imaging procedures during a prolonged hospital course. Therefore, we reviewed a cohort of such patients to identify the sources and quantify the cumulative radiation exposure seen during their hospitalization.

MATERIALS AND METHODS

We retrospectively reviewed a single-center experience with these patients to define the potential for short-term skin injury and long-term oncologic risk due to absorbed radiation dose and sources of ionizing radiation and their contribution to the cumulative absorbed dose to the cranial tissues.

RESULTS

We demonstrated that substantial cumulative doses can be seen, with 87% of the cumulative absorbed dose occurring during neurointerventional procedures and 7% from CT. Mathematic modeling was performed identifying potential techniques to further reduce the cumulative radiation absorbed dose to these patients.

CONCLUSIONS

We conclude that repetitive irradiation during the care of patients with aneurysmal subarachnoid hemorrhage can result in significant cumulative doses and a variety of techniques can be applied to reduce this absorbed dose. Use of radiation for diagnostic and therapeutic purposes during prolonged procedures of patients with subarachnoid hemorrhage demands diligence throughout the hospitalization.

Studies of patient doses in interventional radiological examinations

In Russia, especially in big cities like St. Petersburg, the annual number of interventional radiological (IR) examinations for both diagnostic and treatment purposes is increasing continuously. However, IR examinations might involve high patient doses and even the risk of skin injures that should be prevented. In this study, the exposure of patients caused by these examinations was analysed. Methods for the estimation of the effective dose (risk reduction of stochastic effects) were proposed. Thresholds for kerma-area product values that correspond to the occurrence of skin injury are also given.

Radiation dose and excess risk of cancer in children undergoing neuroangiography

OBJECTIVE

The primary goal of this study was to determine the radiation dose received during diagnostic and interventional neuroangiographic procedures in a group of pediatric patients. A second goal was to approximate the total average radiation dose from all angiographic and CT studies that pediatric patients underwent during the study period and to estimate the increased risk of cancer incidence in this patient group.

MATERIALS AND METHODS

The study subjects were pediatric patients who had undergone one or more neuroangiographic procedures at Harborview Medical Center between December 1, 2004, and April 30, 2008. Recorded radiation doses were converted to entrance skin dose (ESD) and effective dose (ED) to indicate deterministic and stochastic damage, respectively. The Biologic Effects of Ionizing Radiation (BEIR) VII, phase 2, report was used to estimate the expected increased risk of cancer in the study population.

RESULTS

For diagnostic and therapeutic procedures, a mean ED of 10.4 and 34.0 mSv per procedure was calculated, respectively. The ESD values proved too low to cause deterministic harm. The estimated number of excess cases of malignancy projected from the total average radiation exposure was 890.6 per 100,000 exposed male children and 1,222.5 per 100,000 exposed females, an overall increase of approximately 1% to the lifetime attributable risk of cancer.

CONCLUSION

Although both angiography and CT have revolutionized the practice of medicine and confer benefits to patients, it is important that we continue to investigate the possible adverse effects of these technologies. Protocols that minimize radiation dose without compromising a study should be implemented.

Radiation Exposure during Endovascular Procedures

Objective:

The duration of fluoroscopy exposure is routinely recorded as part of endovascular procedures. However, to better relate the duration of exposure to actual doses of surface and intracranial radiation, we compared surface doses during endovascular procedures with intracranial doses in a cadaver model exposed to lateral fluoroscopy.

Methods:

Optically stimulated luminescence dosimeter chips (Landauer, Glenwood, IL) were used to measure the cranial surface dose of three consecutive patients undergoing endovascular procedures. Bitemporal craniotomies were performed on a cadaver. Dosimeter chips were placed on both the ipsilateral and contralateral skin and meningeal surfaces, and the cadaver was exposed to lateral fluoroscopy. Finally, to assess mean fluoroscopy times in patients undergoing embolization procedures, the operative notes of 100 consecutive patients were reviewed.

Results:

Three patients undergoing endovascular treatment received peak doses of 0.24, 0.31, and 1.38 Gy, respectively. In the cadaver, the peak surface dose recorded after 120 minutes of exposure was 1.71 Gy. The cranium and scalp absorbed or reflected 29% of the surface dose. Time in minutes of fluoroscopy was found to correlate with surface dose (R2 = 0.925).

Conclusion:

Our data show that radiation exposure during endovascular treatment can reach clinically significant levels. The surface doses recorded during this study were comparable to the mean dose of 1.5 Gy estimated by others to increase the relative risk of inducing meningiomas, gliomas, and nerve sheath tumors. Pending long-term follow-up of patients exposed to endovascular procedures, consent for possible long-term sequelae of radiation may be warranted.

Comparison of N-Butyl Cyanoacrylate and Onyx for the Embolization of Intracranial Arteriovenous Malformations: Analysis of Fluoroscopy and Procedure Times

Objective:

Intracranial arteriovenous malformations (AVM) may be managed through staged preoperative embolization and resection. Two commonly used liquid embolics are N-butyl cyanoacrylate (nBCA; Cordis Microvascular, Inc., New Brunswick, NJ) and Onyx (ev3, Inc., Irvine, CA). We sought to compare the utility of these agents in terms of fluoroscopy and procedure times.

Methods:

All intracranial AVMs embolized from 2002 to 2006 at the University of Florida were included in this study. Patients were stratified into three treatment groups: nBCA, Onyx, and patients who received both nBCA and Onyx during separate embolizations. Cohorts were compared by sex, age, Spetzler-Martin grade, AVM volume, fluoroscopy time, procedure time, surgical blood loss, and complications.

Results:

A total of 182 embolizations were performed on 88 patients (nBCA, 60 patients and 106 procedures; Onyx, 20 patients and 43 procedures; and nBCA/Onyx, eight patients and 16 nBCA and 17 Onyx procedures). There were no significant differences in patient demographics, AVM volumes, and Spetzler-Martin grades. Mean fluoroscopy and procedure times were increased for Onyx (57 min; 2.6 h) compared with nBCA (37 min; 2.1 h) embolizations (P &lt; 0.0001 and P = 0.001, respectively). Cumulative mean fluoroscopy time was increased for Onyx (135 min) and nBCA/Onyx (180 min) cohorts relative to nBCA (64 min; P &lt; 0.0001). Cumulative mean procedure time was increased in the nBCA/Onyx group (10.4 h) compared with nBCA (3.7 h) and Onyx (5.4 h; P&lt; 0.0001). Seventy patients (80%) underwent AVM resection. No significant differences in surgical blood loss or complication rates were observed among the cohorts.

Conclusion:

Onyx AVM embolization requires increased fluoroscopy and procedure times compared with nBCA. Further investigation is necessary to justify increased radiation exposure and procedure time associated with Onyx.

Patient skin dose during neuroembolization by multiple-point measurement using a radiosensitive indicator

BACKGROUND AND PURPOSE

Although neuroembolization has recently spread quickly, sufficient attention has not been focused on the associated radiation exposure. The purpose of this research was to evaluate the patient's entrance skin dose (ESD) during neuroembolizations in 6 institutions.

MATERIALS AND METHODS

This study was approved by all of the 6 institutional review boards, and all of the patients gave informed consent. This study included a total of 103 consecutive neuroembolizations in the 6 institutions. Patient ESDs during the procedures were evaluated by using caps that had 44 radiosensitive indicators adherent to the surface. The patient ESDs were calculated from the color difference of the indicators. To check for effects on the scalp, clinical follow-up was performed at 1-2 days, 2 weeks, and 3 months after the procedure.

RESULTS

The averages of total fluoroscopic time, total number of digital subtraction angiography frames, and dose area product were 67.1 +/- 41.6 minutes, 883 +/- 626, and 257 +/- 150 Gy x cm(2), respectively. The average maximum ESD for each patient was 1.9 +/- 1.1 Gy (range, 0.4-5.6 Gy; median, 1.5 Gy). The average maximum ESDs of each institution ranged from 1.0 to 2.4 Gy. Epilation was observed in 6 patients.

CONCLUSIONS

The maximum ESDs during neuroembolizations exceed the thresholds for radiation skin injuries in some cases.

Practice of ALARA in the pediatric interventional suite

As interventional procedures have become progressively more sophisticated and lengthy, the potential for high patient radiation dose has increased. Staff exposure arises from patient scatter, so steps to minimize patient dose will in turn reduce operator and staff dose. The practice of ALARA in an interventional radiology (IR) suite, therefore, requires careful attention to technical detail in order to reduce patient dose. The choice of imaging modality should minimize radiation when and where possible. In this paper practical steps are outlined to reduce patient dose. Further details are included that specifically reduce operator exposure. Challenges unique to pediatric intervention are reviewed. Reference is made to experience from modern pediatric interventional suites. Given the potential for high exposures, the practice of ALARA is a team responsibility. Various measures are outlined for consideration when implementing a quality assurance (QA) program for an IR service.