Cumulative Air Kerma Research Articles

Occupational dose reduction in cardiac catheterisation laboratory: a randomised trial using a shield drape placed on the patient.

The aim of this study was to evaluate the occupational radiation dose in interventional cardiology by using a shielding drape on the patient. A random study with and without the protective material was conducted. The following control parameters were registered: demographic data, number of stents, contrast media volume, fluoroscopy time, number of cine images, kerma-area product and cumulative air kerma. Occupational dose data were obtained by electronic active dosemeters. No statistically significant differences in the analysed control parameters were registered. The median dose value received by the interventional cardiologist was 50% lower in the group with a shielding drape with a statistically significant p-value <0.001. In addition, the median value of the maximum scatter radiation dose was 31% lower in this group with a statistically significant p-value <0.001. This study showed that a shielding drape is a useful tool for reducing the occupational radiation dose in a cardiac catheterisation laboratory.

Prostatic artery embolization: radiation exposure to patients and staff

The aim of this study was to evaluate the radiation doses to patients and staff received from the first cases of prostatic artery embolization (PAE) conducted in a public hospital in Recife, Brazil. Five PAE procedures for 5 men diagnosed with benign prostatic hyperplasia were investigated. In order to characterize patient exposure, dosimetric quantities, such as the air kerma-area product (PKA), the cumulative air kerma at the interventional reference point (Ka,r), the number of images, etc, were registered. To evaluate the possibility for deterministic effects, the peak skin dose (PSD) was measured using radiochromic films. For evaluation of personal dose equivalent and effective dose to the medical staff, thermoluminescent dosemeters (TLD-100) were used. The effective dose was estimated using the double dosimetry alghoritm of von Boetticher. The results showed that the mean patient’s PSD per procedure was 2674.2 mGy. With regard to the medical staff, the mean, minimum and maximum effective doses estimated per procedure were: 18 μSv, 12 μSv and 21 μSv respectively. High personal equivalent doses were found for the feet, hands and lens of the eye, due to the use of multiple left anterior oblique projections and the improper use of the suspended lead screen and the lead curtain during procedures.

Integration of kerma-area product and cumulative air kerma determination into a skin dose tracking system for fluoroscopic imaging procedures.

The skin dose tracking system (DTS) that we developed provides a color-coded mapping of the cumulative skin dose distribution on a 3D graphic of the patient during fluoroscopic procedures in real time. The DTS has now been modified to also calculate the kerma area product (KAP) and cumulative air kerma (CAK) for fluoroscopic interventions using data obtained in real-time from the digital bus on a Toshiba Infinix system. KAP is the integral of air kerma over the beam area and is typically measured with a large-area transmission ionization chamber incorporated into the collimator assembly. In this software, KAP is automatically determined for each x-ray pulse as the product of the air kerma/ mAs from a calibration file for the given kVp and beam filtration times the mAs per pulse times the length and width of the beam times a field nonuniformity correction factor. Field nonuniformity is primarily the result of the heel effect and the correction factor was determined from the beam profile measured using radio-chromic film. Dividing the KAP by the beam area at the interventional reference point provides the area-averaged CAK. The KAP and CAK per x-ray pulse are summed after each pulse to obtain the total procedure values in real-time. The calculated KAP and CAK were compared to the values displayed by the fluoroscopy machine with excellent agreement. The DTS now is able to automatically calculate both KAP and CAK without the need for measurement by an add-on transmission ionization chamber.

A Phantom Study and a Retrospective Clinical Analysis to Investigate the Impact of a New Image Processing Technology on Radiation Dose and Image Quality during Hepatic Embolization

PurposeTo investigate changes in radiation dose and image quality using phantoms and hepatic embolization procedures performed with a new image processing technology (ClarityIQ) for a single-plane flat-detector–based interventional fluoroscopy system. Materials and MethodsPhantom study was performed using acrylic sheets simulating different patient sizes. Air kerma rates (AKRs) were compared for different fluoroscopy modes and magnification modes without and with ClarityIQ. Repeat hepatic embolization procedures performed on the same lobe of the liver in the same patient by the same interventional radiologist between January 2013 and July 2014 without and with ClarityIQ were evaluated retrospectively. This included treatment of 33 hepatic lobes in 26 patients. Cumulative air kerma (CAK), kerma–area product (KAP), and factors affecting radiation dose were extracted from study metadata and compared. Blinded randomized image quality review was performed on arteriograms using a five-point scale. ResultsThe phantom study revealed a significantly lower AKR (P < .005) with ClarityIQ. Repeated-measures analysis revealed a significant effect of ClarityIQ (P ≤ .001) on CAK and KAP, with reductions ranging between 9% and 85% (median, 67%) and between 5% and 89% (median, 75%), respectively, on a case-by-case basis. Mean reductions in CAK and KAP were 279 mGy and 134,030 mGy·cm2, respectively. Image quality review scores were significantly lower (P ≤ .001) with ClarityIQ, effecting visualization of tumor vasculature and appearance of noise texture. ConclusionsClarityIQ resulted in radiation dose reduction in the phantom study and in the hepatic embolization procedures, but with a decrease in subjective perceptions of image quality.

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

PurposeTo assess patient radiation doses during cerebral angiography and embolization of intracranial aneurysms across multi-centers and propose a diagnostic reference level (DRL).Materials and MethodsWe 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.ResultsTotal mean DAP, CAK, fluoroscopy time, and total angiographic image frames were 106.2 ± 66.4 Gy-cm2, 697.1 ± 473.7 mGy, 9.7 ± 6.5 minutes, 241.5 ± 116.6 frames for diagnostic procedures, 218.8 ± 164.3 Gy-cm2, 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-cm2 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-cm2 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.ConclusionRadiation 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.

Multicenter Study on Evaluation of the Entrance Skin Dose by a Direct Measurement Method in Cardiac Interventional Procedures

Deterministic effects have been reported in cardiac interventional procedures. To prevent radiation skin injuries in percutaneous coronary intervention (PCI), it is necessary to measure accurate patient entrance skin dose (ESD) and maximum skin absorbed dose (MSD). We measured the MSD on 62 patients in four facilities by using the Chest-RADIREC(Ⓡ) system. The correlation between MSD and fluoroscopic time, dose area product (DAP), and cumulative air kerma (AK) showed good results, with the correlation between MSD and AK being the strongest. The regression lines using MSD as an outcome value (y) and AK as predictor variables (x) was y=1.18x (R(2)=0.787). From the linear regression equation, MSD is estimated to be about 1.18 times that of AK in real time. The Japan diagnostic reference levels (DRLs) 2015 for IVR was established by the use of dose rates using acrylic plates (20- cm thick) at the interventional reference point. Preliminary reference levels proposed by International Atomic Energy Agency (IAEA) were provided using DAP. In this study, AK showed good correlation most of all. Hence we think that Japanese DRLs for IVR should reconsider by clinical patients' exposure dose such as AK.

Determining Fluoroscopic Radiation Exposure to the Urology Resident

Fluoroscopy has grown to become a critical technology for the modern urologist. The safety of fluoroscopic radiation has been evaluated in a variety of settings however it remains understudied in the urology literature. This study evaluates radiation exposure in the urology fluoroscopic suite. Dosimeter badges were worn by resident and attending urologists to measure radiation exposure during fluoroscopic cases. Exposure was also measured by calculating cumulative air kerma for each case type eg., laser lithotripsy, stent placement. It is estimated that the urology resident and the attending are exposed on average to 3.25 Rem/year and 0.46 Rem/year. Physicians spending above average time in the fluoro suite, i.e., urology residents were not exposed to radiation levels above safety guidelines.

Urinary 8-Hydroxy-2′-Deoxyguanosine: A Biomarker for Radiation-Induced Oxidative DNA Damage in Pediatric Cardiac Catheterization

To determine the utility of urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) as a sensitive biomarker for radiation-induced cellular DNA damage in children undergoing cardiac catheterization. We enrolled pediatric patients with congenital heart diseases requiring cardiac catheterization in conjunction with healthy children and children under sedation as control. Demographic, clinical, laboratory and invasive hemodynamic data, urinary 8-OHdG levels, and radiation exposure measurements were collected prospectively. Nineteen patients, 10 healthy children and 9 children under sedation, were studied. In 19 patients who underwent cardiac catheterization, the median level of 8-OHdG in urine obtained at 24-48 hours after the procedure was significantly higher than at baseline (44.0 vs 17.3 ng/mg creatinine, P = .0001). Furthermore, the urinary 8-OHdG level after the procedure increased in 18 of the 19 study subjects. In contrast, there was no significant difference in 8-OHdG levels between the 2 spot urine samples obtained at arbitrary intervals of 24-48 hours in 10 healthy children (P = .7213), and at baseline and 24-48 hours following echocardiography in 9 children under sedation (P = .1097). Stepwise multiple regression analysis revealed that the cumulative air kerma during the cardiac catheterization was the variable which was strongly and significantly associated with the ratio of post- to precardiac catheterization urinary 8-OHdG levels among the evaluated variables (R(2) = 0.7179, F = 11.0256, P = .0007). Urinary 8-OHdG could be a useful biomarker for radiation-induced cellular DNA damage in children undergoing diagnostic cardiac catheterization.

Improving Patient Safety: Implementing Dose Monitoring Software in Fluoroscopically Guided Interventions

PurposeTo assess whether dose monitoring software can be successfully implemented in fluoroscopically guided interventions and to provide dose data based on levels of complexity. Materials and MethodsAfter launching the software (DoseWatch; GE Healthcare Systems, Buc, France), data were collected for 6 months and analyzed by means of kerma-area product (KAP; Gy/cm2), cumulative air kerma (KA,R; Gy), and fluoroscopic time (minutes). Data analysis was executed by level of complexity as graded by the operators. Complexity grading was based on factors such as tortuosity and calcification of vessel, variant anatomy, and patient cooperation. ResultsThe software successfully transferred dose data of 357 fluoroscopically guided procedures. KAP was 0.238–400 Gy/cm2 with mean, median, and 75th percentile values of 46.0 Gy/cm2, 163.2 Gy/cm2, and 541.1 Gy/cm2 (KA,R, 0.013–4.1 Gy; mean, median, 75th percentile, 0.48 Gy, 0.97 Gy, 3.98 Gy). Highest dose values were seen in transarterial chemoembolization (KAP mean, median, 75th percentile, 229.5 Gy/cm2, 216.4 Gy/cm2, 299.9 Gy/cm2; KA,R mean, median, 75th percentile, 1.9 Gy, 1.2 Gy, 1.7 Gy). Analysis revealed that the level of complexity strongly correlated with KAP (r = 0.88; P < .001) whereas there was no direct correlation of KAP and fluoroscopy time. During the same intervention, KA,R and fluoroscopy time increased with level of complexity, but the correlation was not statistically significant. ConclusionsImplementation of dose monitoring software in fluoroscopically guided interventions can be successfully accomplished, and it facilitates data comparison.

Patient Radiation Dose Reduction during Transarterial Chemoembolization Using a Novel X-Ray Imaging Platform

PurposeTo evaluate radiation dose reduction in patients undergoing transarterial chemoembolization with the use of a new image acquisition and processing platform. Materials and MethodsRadiation-dose data were obtained from 176 consecutive chemoembolization procedures in 135 patients performed in a single angiography suite. From January 2013 through October 2013, 85 procedures were performed by using our institution’s standard fluoroscopic settings. After upgrading the x-ray fluoroscopy system with an image acquisition and processing platform designed to reduce image noise and reduce skin entrance dose, 91 chemoembolization procedures were performed from November 2013 through December 2014. Cumulative dose–area product (CDAP), cumulative air kerma (CAK), and total fluoroscopy time were recorded for each procedure. Image quality was assessed by three interventional radiologists blinded to the x-ray acquisition platform used. ResultsPatient radiation dose indicators were significantly lower for chemoembolization procedures performed with the novel imaging platform. Mean CDAP decreased from 3,033.2 dGy·cm2 (range, 600.3–9,404.1 dGy·cm2) to 1,640.1 dGy·cm2 (range, 278.6–6,779.9 dGy·cm2; 45.9% reduction; P < .00001). Mean CAK decreased from 1,445.4 mGy (range, 303.6–5,233.7 mGy) to 971.7 mGy (range, 144.2–3,512.0 mGy; 32.8% reduction; P < .0001). A 20.3% increase in mean total fluoroscopy time was noted after upgrading the imaging platform, but blinded analysis of the image quality revealed no significant degradation. ConclusionsAlthough a small increase in fluoroscopy time was observed, a significant reduction in patient radiation dose was achieved by using the optimized imaging platform, without image quality degradation.

Direct physician reporting is associated with reductions in radiation exposure in pediatric cardiac catheterizations.

The objective is to quantify radiation dose in children undergoing cardiac catheterization and determine the impact of increased reporting transparency on total radiation exposure. Cardiac catheterization (cath) can result in significant radiation exposure in children. There has been growing interest in quantifying and reducing radiation exposure in pediatric cath procedures. Our center underwent a slight change in practice recently that resulted in direct physician reporting of radiation dose following every case. We reviewed cath procedures across three different eras in four cath categories: post-heart transplant annual cath, unilateral pulmonary artery (PA) stent placement, pre-Fontan cath, and pre-Glenn cath. The eras were defined as: Era 1, 1/2009-1/2011; Era 2, 1/2011-9/2013; and Era 3, 9/2013-5/2014. In Era 3, the physician performing the cath was responsible for reporting the radiation data. Across the three eras, there were significant decreases in cumulative air KERMA (mGy) among all four cath categories. From Era 2 to Era 3, the greatest decreases in radiation were noted, particularly in dose area product (cGy·cm2) in the transplant annual evaluation and pre-Glenn cases. In Era 1, 2 cases (1.2%) had a frame rate reduction, while in Era 2, 22 cases (12.0%), and in Era 3, 83 cases (21.6%) had frame rate changes (P<0.01). Increased physician awareness of radiation exposure is associated with a significant reduction in radiation dose across a variety of cath procedures. This is seen not only by the overall reduction in radiation across case types, but also as the frame rate was more frequently changed during individual cases, indicating an important change in physician behavior and practice.

TH-AB-201-02: Fluoroscopy-Guided Radiation Dose; Best Correlated to Patient Thickness

Purpose: To survey a radiation dose index of peripheral and trunk fluoroscopic interventional procedures at a tertiary care pediatric hospital. These results allow the correlation of a patient dose index to the patient thickness, age, weight, and body mass index (BMI) to be analyzed. Methods: Radiation dose structured reports were retrospectively collected for pediatric and adult interventional fluoroscopic cases. Kerma Area Product (KAP), air Kerma (AK), fluoroscopy time (FT), thickness of body part irradiated, patient’s age, height, and weight were collected. Cumulative AK was divided by fluoroscopy time to normalize the dose index by the complexity of the case. This index for each study was analyzed as a function of thickness of body part irradiated, patient age, weight, and BMI. Non-parametric correlation coefficients along with the 95% confidence intervals were computed to investigate which parameter correlates best with patient dose. Results: A total of 522 cases were included in the study. The patients’ irradiated body part thicknesses, ages, masses, and heights ranged from 1–35 cm, 0.01–61 years, 1.4–145.5 kg, and 37.5–190 cm respectively. The FT and AK of the cases ranged from 0.1–100 min and 0.1–2756 mGy respectively. The correlation with 95% confidence interval of AK/FT to each patient parameter is listed in the supporting document. Each patient parameter is statistically correlated with patient dose (p-value < 0.0001), however the correlation with patient thickness statistically provides the highest correlation whereas the three other parameters are of similar, lower correlation. Conclusion: Fluoroscopy-guided patient dose indices should be reported as a function of patient thickness irradiated as opposed to the patient’s age, weight, or BMI. If the thickness of the patient is unknown, our results suggest that any of the other three patient charateristics could be used. K Strauss serves as a consultant to Philips Healthcare upon their request. R Nachabe is a paid employee of Phillips Healthcare.

Radiation exposure to patients and medical staff in hepatic chemoembolisation interventional procedures in Recife, Brazil.

The purpose of this study was to evaluate patient and medical staff absorbed doses received from transarterial chemoembolisation of hepatocellular carcinoma, which is the most common primary liver tumour worldwide. The study was performed in three hospitals in Recife, capital of the state of Pernambuco, located in the Brazilian Northeastern region. Two are public hospitals (A and B), and one is private (C). For each procedure, the number of images, irradiation parameters (kV, mA and fluoroscopy time), the air kerma-area product (PKA) and the cumulative air kerma (Ka,r) at the reference point were registered. The maximum skin dose (MSD) of the patient was estimated using radiochromic film. For the medical staff dosimetry, thermoluminescence dosemeters (TLD-100) were attached next to the eyes, close to the thyroid (above the shielding), on the thorax under the apron, on the wrist and on the feet. The effective dose to the staff was estimated using the algorithm of von Boetticher. The results showed that the mean value of the total PKA was 267.49, 403.83 and 479.74 Gy cm(2) for Hospitals A, B and C, respectively. With regard to the physicians, the average effective dose per procedure was 17 µSv, and the minimum and maximum values recorded were 1 and 41 µSy, respectively. The results showed that the feet received the highest doses followed by the hands and lens of the eye, since the physicians did not use leaded glasses and the equipment had no lead curtain.

Implications in medical imaging of the new ICRP thresholds for tissue reactions.

The International Commission on Radiological Protection (ICRP) statement on tissue reactions, issued by the Commission in April 2011, reviewed epidemiological evidence and suggested that there are some tissue reactions where threshold doses are or may be lower than those previously considered. For the lens of the eye, the threshold is now considered to be 0.5 Gy. The absorbed dose threshold for circulatory disease in the heart and brain may be as low as 0.5 Gy. These values can be reached in some patients during interventional cardiology or neuroradiology procedures. They may also be of concern for repeated computed tomography examinations of the head. The new thresholds should be considered in optimisation strategies for clinical procedures, especially in patients likely to require repeated interventions. The new dose thresholds also affect occupational protection for operators and staff. Some operators do not protect their eyes or their brain adequately. After several years of work without proper protection, the absorbed doses to the lens of the eye and the brain of staff can exceed 0.5 Gy. More research is needed to understand the biological effects of cumulative incident air kerma and the instantaneous air kerma rates currently used in medical imaging. The new thresholds, and the need for specific occupational dosimetry related to lens doses, should be considered in radiation protection programmes, and should be included in the education and training of professionals involved in fluoroscopy guided procedures and computed tomography.

Evaluation of a real-time display for skin dose map in cardiac catheterisation procedures.

The purpose of this work was to validate a prototype designed to display skin dose maps in real time for clinicians that perform interventional cardiology procedures. Measurements using copper absorbers and three kinds of dosemeters (solid-state, radiochromic film and optically stimulated luminescence) were performed in a catheterisation laboratory. Some clinical results are also discussed. The system provides patient skin doses with acceptable accuracy, taking into account couch shifts, wedge compensation filters and collimation. The greatest source of uncertainty is that resulting from patient shape modelling. From a set of 374 patients recorded, it can be concluded that the peak skin dose (PSD) for patients with the same cumulative air kerma at the patient entrance reference point can be rather different. This real-time skin dose calculator has resulted easier to manage for measuring patient PSDs than other methods based on films or CR plates. As well as an improvement for patient safety, it could prove a useful training tool for clinicians.

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.

SU-C-18C-06: Radiation Dose Reduction in Body Interventional Radiology: Clinical Results Utilizing a New Imaging Acquisition and Processing Platform

Purpose: To quantify the patient radiation dose reduction achieved during transarterial chemoembolization (TACE) procedures performed in a body interventional radiology suite equipped with the Philips Allura Clarity imaging acquisition and processing platform, compared to TACE procedures performed in the same suite equipped with the Philips Allura Xper platform. Methods: Total fluoroscopy time, cumulative dose area product, and cumulative air kerma were recorded for the first 25 TACE procedures performed to treat hepatocellular carcinoma (HCC) in a Philips body interventional radiology suite equipped with Philips Allura Clarity. The same data were collected for the prior 85 TACE procedures performed to treat HCC in the same suite equipped with Philips Allura Xper. Mean values from these cohorts were compared using two-tailed t tests. Results: Following installation of the Philips Allura Clarity platform, a 42.8% reduction in mean cumulative dose area product (3033.2 versus 1733.6 mGycm∧2, p < 0.0001) and a 31.2% reduction in mean cumulative air kerma (1445.4 versus 994.2 mGy, p < 0.001) was achieved compared to similar procedures performed in the same suite equipped with the Philips Allura Xper platform. Mean total fluoroscopy time was not significantly different between the two cohorts (1679.3 versus 1791.3 seconds, p = 0.41). Conclusion: This study demonstrates a significant patient radiation dose reduction during TACE procedures performed to treat HCC after a body interventional radiology suite was converted to the Philips Allura Clarity platform from the Philips Allura Xper platform. Future work will focus on evaluation of patient dose reduction in a larger cohort of patients across a broader range of procedures and in specific populations, including obese patients and pediatric patients, and comparison of image quality between the two platforms. Funding for this study was provided by Philips Healthcare, with 5% salary support provided to authors K. Pallav Kolli and Robert G. Gould for time devoted to the study. Data acquisition and analysis was performed by the authors independent of the funding source.

Patient radiation exposure during general fluoroscopy examinations.

The purpose of this study was to assess the level of patient radiation dose received in general fluoroscopy examinations, compare the findings with the international diagnostic reference levels (IDRLs), and establish the initial institutional (local) LDRLs. A comprehensive survey was conducted for general fluoroscopy examinations using the medical records of a Radiology Department of a leading regional hospital over a period close to one year. The cumulative reference point air kerma (Ka,r), kerma area product (KAP) and fluoroscopy time (FT) were recorded for six hundred and fifty (30% pediatric and 70% adult) patients undergoing routine fluoroscopy examinations using X‐ray equipment with built‐in integrated dose measuring system. Results which were obtained for adult general fluoroscopy indicated that 83% and 33% were below the IDRLs for KAP and fluoroscopy time, respectively. In children, 60% were found to be below the only available KAP diagnostic reference levels. Local diagnostic reference levels (LDRLs) have been proposed with respect to the missing DRLs for the Ka r, KAP, and fluoroscopy time. The majority of the examinations in the study were performed with longer fluoroscopy time, patient dose values per examination type were found to be broad and the mean values above the international diagnostic reference levels. This calls for proper and improved training and radiation protection skills for the responsible personnel, especially the equipment operators.PACS numbers: 87.53.Bn, 87.59.C‐, 87.59.cf, 87.53.Bn, 87.50.‐a, 87.53.‐j

Establishing diagnostic reference levels for interventional procedures in Kenya

PurposeTo quantify ionizing radiation exposure to patients during interventional procedures and establish national diagnostic reference levels (NDRLs) for clinical radiation exposure management. MethodsThe cumulative reference point air kerma, kerma area product, fluoroscopy time and other operational parameters were monitored for 50 children and 261 adult patient procedures in five catheterization medical laboratories in Kenya. To estimate the risk associated with the exposure, effective doses were derived from the kerma area product using conversion factors from Monte Carlo models. ResultsAbout 3% of the measured cumulative reference point air kerma for the interventional procedures approached the threshold dose limit with the potential to cause deterministic effects such as skin injuries. In interventional cardiology, the results obtained for both children and adults indicated 33% were below the diagnostic reference levels (DRLs). In adult interventional radiology, 29% for cumulative reference point air kerma, and 43% for kerma area product and fluoroscopy time respectively were below the diagnostic reference levels. NDRLs were proposed for routine use in the procedures considered and for the non-existent DRLs situations in paediatric interventional cardiology. ConclusionThe measured patient doses were above the DRLs available in the literature indicating a need for radiation optimization through, continuous monitoring and recording of patient dose. To promote radiation safety, facilities performing interventional procedures need to establish a radiation monitoring notification threshold for possible deterministic effects, in addition to the use of the newly established national diagnostic reference levels, as a quality assurance measure.

Radiation dose in neuroangiography using image noise reduction technology: a population study based on 614 patients

IntroductionThe purpose of this study was to quantify the reduction in patient radiation dose by X-ray imaging technology using image noise reduction and system settings for neuroangiography and to assess its impact on the working habits of the physician.MethodsRadiation dose data from 190 neuroangiographies and 112 interventional neuroprocedures performed with state-of-the-art image processing and reference system settings were collected for the period January–June 2010. The system was then configured with extra image noise reduction algorithms and system settings, which enabled radiation dose reduction without loss of image quality. Radiation dose data from 174 neuroangiographies and 138 interventional neuroprocedures were collected for the period January–June 2012. Procedures were classified as diagnostic or interventional. Patient radiation exposure was quantified using cumulative dose area product and cumulative air kerma. Impact on working habits of the physician was quantified using fluoroscopy time and number of digital subtraction angiography (DSA) images.ResultsThe optimized system settings provided significant reduction in dose indicators versus reference system settings (p<0.001): from 124 to 47 Gy cm2 and from 0.78 to 0.27 Gy for neuroangiography, and from 328 to 109 Gy cm2 and from 2.71 to 0.89 Gy for interventional neuroradiology. Differences were not significant between the two systems with regard to fluoroscopy time or number of DSA images.ConclusionX-ray imaging technology using an image noise reduction algorithm and system settings provided approximately 60% radiation dose reduction in neuroangiography and interventional neuroradiology, without affecting the working habits of the physician.