ALARA Principle Research Articles

Electrophysiological procedures for the use of the RPC: without hindrance and negligible radiation

Background: Fluoroscopy is the main visualization technique for EP procedures. A radiation protection cabin (RPC) shielded with 2 mm lead-equivalent walls was tested as an alternative protection tool (Cathpax®, Lemer Pax). Methods: To assess the scattered radiation to the operator inside the RPC an electronic personal dosimeter (EPD; Mk2, Thermo Electron) was placed at the neck level of the operator. A second EPD was located outside the RPC at 150 cm height from the floor, to record the presumable head radiation dose. Results: Radiation doses were measured in a total of 138 consecutive patients (age 54±16 yrs, BMI 28±5 kg/m2 (18-45), 64% male) undergoing a variety of ablation procedures (SVT=75, AFL=32, AF=17, VT=14). Median fluoroscopy time was 39 min (7-140), the cumulative dose-area product (DAP) 4702 cGy.cm2 (493-65620). Doses outside the RPC showed a median of 135 µSv (1-4881). Doses inside the RPC were detected only at sensitivity threshold or background levels (mean 0.2SD0.7 µSv, median 0.0, range 0-4). The dose reduction to the operator was highest for AF ablations (354 vs 0.5 µSv, respectively; p<0.001). The total accumulated dose outside the RPC was 37883 µSv for all 138 procedures, whereas for the protected operator inside only 30 µSv. Conclusions: There were highly concordant low dose values measured for the operator inside the RPC in comparison to high doses outside the RPC. The use of a RPC represents a major benefit over a lead apron and contributes to a significant dose reduction as low as reasonably achievable (ALARA principle).

Radiation Dose Reduction During EVAR: Results from a Prospective Multicentre Study (The REVAR Study)

To evaluate radiation exposure in standard endovascular aneurysm repair (EVAR) using intra-operative guidance with pre-operative computed tomographic angiography (CTA) fusion and strict ALARA guidelines in a modern hybrid room. Between February and November 2016, consecutive patients with AAA undergoing EVAR with a bifurcated device in a hybrid room under fusion imaging guidance were prospectively enrolled in six aortic centres from the United States (n = 1), Europe (n = 4), and Japan (n = 1). Demographic data including body mass index (BMI), indirect dose area product (DAP), cumulative air kerma (CAK), variables influencing dose delivery, and contrast media volume were collected. 85 patients (90.4% males) were included. The median age was 75 (IQR 69–81), with a median BMI of 27.4 (IQR 24.7–30.6). Median DAP and CAK were 14.7 (IQR 10.0–27.7) Gy·cm2 and 107 (IQR 68.0–189.0) mGy, respectively. The median contrast volume was 47 mL (IQR 35–70) (equivalent to 14.1g of iodine [IQR 10.5–21.0]). Median DAP per centre was 28.1 (n = 16, IQR 12.6–47.1), 15.9 (n = 11, IQR 11.9–22.5), 14.2 (n = 12, IQR 10.9–25.7), 20.2 (n = 18, IQR 7.0–39.5), 10.3 (n = 27, IQR 8.2–14.7) and 26.5 (n = 1) Gy·cm2. In multivariable analysis, collimation was the only factor that was significantly associated with DAP reduction, (coefficient = −0.014 per percentage of collimation, 95% CI −0.019 to −0.008, p < .001). With adherence to the ALARA principle and routine application of fusion imaging guidance for EVAR, low radiation exposure compared with the published literature can be achieved in a real world setting.

P114] Effective dose for medical workers during Y-90 microshperes radioembolization

Introduction Due to the increasing need for radioemblization of liver cancer with Yttrium 90 microspheres a new need for evaluation of the radiation exposure of the medical staff is necessary. The objective of this study is to assess occupational exposure for nuclear medicine, radiology and clinical staff involved in Y90 preparation and implantation. Although there are guidelines and regulation regarding the use of radioisotopes for therapy when a new teaqnic is used for first time new measurements should be perform in order to reduce the occupational radiation doses to the workers. Material & Method To estimate the effective dose from external exposure the nuclear medicine physician and the medical physicist had electronic dosimeters and TLD badges worn at the upper pocket of their overall, TLD rings on the second finger of each hand. The basics stages for radioemblization procedures involve 3 steps: measuring the Y-90 vial, segmentation of the dose, transport to radiology, implantation of the radiopharmaceutical. Results The results of our study for the average cumulative whole body dose for 22 patients ( μ Sv ± SD) at different stages were: measuring the Y-90 vial, segmentation of the dose, transport to radiology, 132 ± 7,23 (Medical Physicist), implantation of the radiopharmaceutical 197 ± 6,67 (Nuclear Medicine Physician). The mean finger exposures for the Medical Physicist were 132 ± 76 μ Sv/GBq. For administration of resin microspheres, mean finger exposures for the Nuclear Medicine Physician were 197.5 ± 90 μ Sv/GBq. Conclusion Medical staff performing radioembolization procedures is exposed to safe levels of radiation. The personnel dose results are significantly lower than the recommended annual dose by International Commission for Radiological Protection. However a greater effort should be made to reduce the doses further in line with the ALARA principle.

Neutronic effects of diagnostic shield module length on radiation environment of ITER diagnostic generic upper port plug

Newly developed 3D CAD-based MCNP neutronics model of ITER Diagnostic Generic Upper Port Plug (DGUPP) is a baseline MCNP model of the ITER tokamak Upper Port Plug. This paper presents 3D neutron flux and Shut-Down Dose Rate (SDDR) maps for the DGUPP integrated into the MCNP C-lite V2 global model. The SDDR assessments have been performed with the R2Smesh approach and focused on the UPP Inter-Space Structure (ISS), where personnel access is planned. Following the ALARA principle, SDDR in the ISS should be minimized, for that reason the length of the Diagnostic Shielding Module (DSM) was extended by filling all the UP structure till the UP Closure Plate with the DSM shielding material. The corresponding MCNP model was called DGUPP “long-DSM”, in contrast to the original CAD-based “short-DSM”. The results of the DSM extension indicated that the strongest, up to 3 times reduction of fluxes & SDDR could be reached at the UP Closure Plate, while inside the maintenance corridors the SDDR reduction is 11%. Found possibility to reduce the SDDR emphasizes the importance of this work.

Radiation Dose Reduction During EVAR: Results from a Prospective Multicentre Study (The REVAR Study)

To evaluate radiation exposure in standard endovascular aneurysm repair (EVAR) using intra-operative guidance with pre-operative computed tomographic angiography (CTA) fusion and strict ALARA guidelines in a modern hybrid room. Between February and November 2016, consecutive patients with AAA undergoing EVAR with a bifurcated device in a hybrid room under fusion imaging guidance were prospectively enrolled in six aortic centres from the United States (n=1), Europe (n=4), and Japan (n=1). Demographic data including body mass index (BMI), indirect dose area product (DAP), cumulative air kerma (CAK), variables influencing dose delivery, and contrast media volume were collected. 85 patients (90.4% males) were included. The median age was 75 (IQR 69-81), with a median BMI of 27.4 (IQR 24.7-30.6). Median DAP and CAK were 14.7 (IQR 10.0-27.7) Gy·cm2 and 107 (IQR 68.0-189.0) mGy, respectively. The median contrast volume was 47mL (IQR 35-70) (equivalent to 14.1g of iodine [IQR 10.5-21.0]). Median DAP per centre was 28.1 (n=16, IQR 12.6-47.1), 15.9 (n=11, IQR 11.9-22.5), 14.2 (n=12, IQR 10.9-25.7), 20.2 (n=18, IQR 7.0-39.5), 10.3 (n=27, IQR 8.2-14.7) and 26.5 (n=1) Gy·cm2. In multivariable analysis, collimation was the only factor that was significantly associated with DAP reduction, (coefficient=-0.014 per percentage of collimation, 95% CI -0.019 to -0.008, p<.001). With adherence to the ALARA principle and routine application of fusion imaging guidance for EVAR, low radiation exposure compared with the published literature can be achieved in a real world setting.

CT Angiography in the Lower Extremity Peripheral Artery Disease Feasibility of an Ultra-Low Volume Contrast Media Protocol

PurposeThe ALARA principle is not only relevant for effective dose (ED) reduction, but also applicable for contrast media (CM) management. Therefore, the aim was to evaluate the feasibility of an ultra-low CM protocol in the assessment of peripheral artery disease (PAD).Materials and methodsFifty PAD patients were scanned on third-generation dual-source computed tomography, from diaphragm to the forefoot, as follows: tube voltage: 70 kV, reference effective tube current: 90 mAs, collimation: 192 × 2 × 0.6 mm, with individualized acquisition timing. The protocol ED (mSv) was quantified with dedicated software. CM protocol consisted of 15 ml test bolus and 30 ml main bolus (300 mgI/ml) injected at 5 ml/s, followed by a 40 ml saline chaser at the same flow rate. Aorto-popliteal bolus transit time was used to calculate the overall acquisition time and delay. Objective (hounsfield units—HU; contrast-to-noise ratio—CNR) and subjective image quality (four-point Likert score) were assessed at different anatomical regions from the aorta down to the forefoot.ResultsMean attenuation values were exceeding 250 HU from aorta down to the anterior tibial artery with CNR < 13. However, decline in attenuation was observed in more distal region with mean values of 165 and 199 HU, in left and right dorsalis pedis artery, respectively. Mode subjective image quality from the level of aorta down to the popliteal segment was excellent; below the knee mode score was good. The mean ED per protocol was 1.1 ± 0.5 mSv.ConclusionUse of an ultra-low CM volume protocol at 70 kV is feasible in the evaluation of PAD, resulting in good to excellent image quality with mean ED of 1.1 ± 0.5 mSv.Level of evidenceLevel 3, Local non-random sample

Image guidance doses delivered during radiotherapy: Quantification, management, and reduction: Report of the AAPM Therapy Physics Committee Task Group 180

With radiotherapy having entered the era of image guidance, or image-guided radiation therapy (IGRT), imaging procedures are routinely performed for patient positioning and target localization. The imaging dose delivered may result in excessive dose to sensitive organs and potentially increase the chance of secondary cancers and, therefore, needs to be managed. This task group was charged with: a) providing an overview on imaging dose, including megavoltage electronic portal imaging (MV EPI), kilovoltage digital radiography (kV DR), Tomotherapy MV-CT, megavoltage cone-beam CT (MV-CBCT) and kilovoltage cone-beam CT (kV-CBCT), and b) providing general guidelines for commissioning dose calculation methods and managing imaging dose to patients. We briefly review the dose to radiotherapy (RT) patients resulting from different image guidance procedures and list typical organ doses resulting from MV and kV image acquisition procedures. We provide recommendations for managing the imaging dose, including different methods for its calculation, and techniques for reducing it. The recommended threshold beyond which imaging dose should be considered in the treatment planning process is 5% of the therapeutic target dose. Although the imaging dose resulting from current kV acquisition procedures is generally below this threshold, the ALARA principle should always be applied in practice. Medical physicists should make radiation oncologists aware of the imaging doses delivered to patients under their care. Balancing ALARA with the requirement for effective target localization requires that imaging dose be managed based on the consideration of weighing risks and benefits to the patient.

Conclusions and recommendations from the 17th Workshop of the European ALARA Network ‘ALARA in emergency exposure situations’

The European ALARA Network regularly organises workshops on topical issues in radiation protection. In light of the Fukushima accident, the most recent workshop questioned the application of the ALARA principle in emergency exposure situations. This memorandum presents the conclusions and recommendations of this workshop. One of the outcomes is that the process of optimisation in emergency exposure situations should be flexible enough to be able to modify or refine decisions over the course of an accident. In the urgent phase, decisions must be made in a very time-constrained environment, based on scarce, uncertain and sometimes unreliable information. In this phase, optimisation and protection strategies are therefore developed and applied on the basis of conservative assumptions or ‘reasonably foreseeable worst-case scenario’ which could lead to an overestimation of the consequences. In the intermediate phase, knowledge of the situation improves, and more time is available to make the decision. This is reflected by adopting a less conservative approach, and transitioning to a more appropriate optimisation adapted as effectively as possible to the various exposure situations. When the situation is eventually stabilized (transition phase), there is time to shape the measures taken previously to reflect local conditions in the affected territories. In every phase, consideration should be given to the stakeholders, so that their needs and requirements can be incorporated as effectively as possible.

441: Applicability of standardized fetal heart examination in obese population at first trimester

Evaluate the influence of maternal obesity on demonstration of standard fetal cardiac landmarks at first trimester screening This is a secondary analysis of a prospective study of serial cardiac exams in high-risk fetuses. At the time of first trimester screening (Nuchal translucency, nasal bone, anatomy, Doppler, and serum testing) we added standardized fetal heart exam using 2D ultrasound with power Doppler, following the ALARA principle. Standardized protocol: 4-chamber view (4ChV), outflow tract relationship (OTR), transverse arches view (TAV). (Figure 1) Obesity was stratified by Body Mass Index: group 1 <30, group 2 30-40, group 3 40-50, group 4 >50. Successful visualization of cardiac landmarks (4ChV, OTR, TAV), route of study (transabdominal v transvaginal (TV)) and length of the combined exam (duration) were compared between obese and non-obese women. Findings were confirmed by second trimester and/or postnatal echocardiography. Categorical values were compared using Fisher’s exact test. Subgroup analysis was performed using linear-by-linear association We performed 154 fetal heart exams. Median crown rump length was 67.6mm (45.4-90.5). About half the mothers were obese (49%, n=76). The standardized protocol successfully identified 4ChV in all fetuses. OTR and TAV were shown in 99% and 97% in non-obese and obese women respectively (p>0.05 for all). TV exam was required more often in obese women (10/76 v 1/78 non-obese, p<0.01). Exam duration was increased in obese women (34min v 40min, p=0.01). Visualization of the landmarks was not different in obesity subgroup analysis (p>0.05 for all). Conversion to TV route increased with increasing BMI category (1.3%, 9.3%, 16% and 25% in groups 1 to 4 respectively, p=0.01). There was a trend to step-wise increase in total duration from Group 1 to 4 (34, 39, 40 and 45 minutes, respectively p=0.06). All serious cardiac defects were correctly diagnosed in both groups, although the numbers do not allow formal analysis (3 in non-obese, one hypoplastic L heart in the obese group.) Obesity does not hamper visualization of cardiac anatomical landmarks in the first trimester when this standardized method is used. Obesity may require more transvaginal exams without significantly prolonging the scanning time. Obese women should not be excluded from first trimester cardiac assessment.

Awareness of Radiation Protection Measures among Radiologists and Non-Radiologists

Background: More than 3,600 million radiology examinations are carried out every year worldwide. In spite of the great benefits of diagnostic and therapeutic radiations, they may result in some hazards if used inappropriately. However, these hazards can be prevented through raising the awareness of health care professionals about these hazards and the protective measures to be considered. Several guidelines and regulations were issued for this purpose including; the POPUMET regulations and ALARA principle and the WHO global initiative on radiation safety in health care settings. Aim: The current study aimed at assessing the level of radiation protection awareness among clinicians and radiologists in addition to exploring if radiation protection courses have a beneficial effect on the awareness level or not. Methods: This was a cross-sectional study where the level of radiation protection awareness was assessed using an anonymous questionnaire. Results: A total of 101 (100%) participants responded to the questionnaire. Of which; 49 (48.5%) were residents, 30 (29.7%) were specialists and 22 participants (21.8%) were consultants. Slightly less than half of the participants (48, 47.5%) have attended a radiation protection course before. The majority of participants who attended a course (68.8%) have heard about the POPUMET regulations (p<0.001). Participants were asked about the procedures with risk equivalent to 0.25 mSy of radiation estimated dose equivalent. And it was found that course attendance improved the knowledge about the risk of 3 (out of 4) procedures (p 0.05) or the degree of radio-sensitivity of different organs (p>0.05). The majority of the participants (96%) were not aware that there is no annual limit of radiation dose for patients. Around half of the participants (56.4%) were aware about what the word “ALARA” stands for. Conclusion: Results of the current study suggested that the level of radiation protection awareness among health care professionals is not sufficient to ensure patients and workers’ safety. And accordingly, we suggested that more efficient awareness programs for health care professionals are conducted on regular basis with regular monitoring of awareness level to explore areas for improvement.

Multidimensional Model for Assessing Risks from Occupational Radiation Exposure of Workers

The current radiation risk assessment for occupational exposure is based on the measured exposure dose and health checkups of workers. This people-centered risk assessment may occur errors because absence of using personal dosimeter or unrelated health symptoms of individuals lead to difficulties in obtaining accurate data from workers. In addition, although the established legal upper dose limit was used as a reference for the assessment, it does not imply that this limit is the optimal dose of radiation workers should get; ALARA principle should always be appreciated. Therefore, a new risk assessment model that can take account of all the important factors and implement optimization of radiation protection is required at the national level. In this paper, based on the KOSHA Risk Assessment, we studied on the workplace-centered risk assessment model for radiation field rather than the people-centered. The result of the study derived a right model for radiation field through the analysis of the risk assessment methods in various fields and also found data acquisition methods and procedures for applying to the model. Multidimensional model centering on the workplace will enables more accurate radiation risk assessment by using a risk index and radar plot, and consequently contribute to the efficient worker management, preemptive worker protection and implementation of optimization of radiation protection.

Iterative algorithms for artifact reduction in computed tomography

Computed tomography (CT) acquisition should be performed following the ALARA principle: keeping patient radiation exposure as low as reasonably achievable. Reconstruction with filtered backprojection is still the standard in CT. Recently, iterative reconstruction techniques have become available, using adifferent approach for image reconstruction. Asimilar approach is used for iterative metal artifact reduction. Compared to filtered backprojection, iterative reconstruction yields improvements in image quality and reduces image noise. Using iterative reconstruction allows the reduction of patient radiation exposure by up to 80%, depending on the used algorithm and the clinical task at hand. With the help of iterative metal artifact reduction, images of diagnostic quality can be acquired despite metal implants. Iterative reconstruction should be used to reduce patient radiation exposure in accordance with the clinical requirements. The use of iterative metal artifact reduction is recommended.

Digital imaging and radiographic practise in diagnostic radiography: An overview of current knowledge and practice in Europe

IntroductionRecent research has identified the issue of ‘dose creep’ in diagnostic radiography and claims it is due to the introduction of CR and DR technology. More recently radiographers have reported that they do not regularly manipulate exposure factors for different sized patients and rely on pre-set exposures. The aim of the study was to identify any variation in knowledge and radiographic practice across Europe when imaging the chest, abdomen and pelvis using digital imaging. MethodsA random selection of 50% of educational institutes (n = 17) which were affiliated members of the European Federation of Radiographer Societies (EFRS) were contacted via their contact details supplied on the EFRS website. Each of these institutes identified appropriate radiographic staff in their clinical network to complete an online survey via SurveyMonkey. Data was collected on exposures used for 3 common x-ray examinations using CR/DR, range of equipment in use, staff educational training and awareness of DRL. Descriptive statistics were performed with the aid of Excel and SPSS version 21. ResultsA response rate of 70% was achieved from the affiliated educational members of EFRS and a rate of 55% from the individual hospitals in 12 countries across Europe. Variation was identified in practice when imaging the chest, abdomen and pelvis using both CR and DR digital systems. There is wide variation in radiographer training/education across countries. ConclusionThere is a need for standardisation of education and training including protocols and exposure parameters to ensure that there is continued adherence to the ALARA principle.

Synthesis of reflections and conclusions of the SFRP-IRPA workshop on the reasonableness in the practical implementation of the ALARA principle

For almost two years, the International Radiological Protection Association (IRPA) has been engaged in a reflection on the implementation of the radiological protection system and its evolution. In this context, the French Society for Radiological Protection (SFRP) organised a workshop on the search for a level of protection judged to be “reasonable” in the practical implementation of the optimisation approach held in Paris, last February 2017. The objective of this workshop was to initiate a discussion on the foundations of the optimisation principle and to share experience feedback on its implementation in three areas: the nuclear sector (particularly for occupational exposures), the medical sector and some existing exposure situations (exposure to radon, management of radium contaminated sites and management of post-accident situations). The article summarizes the discussions and conclusions of the workshop. It appears that the practical implementation of optimisation as well as the evaluation of the protection level considered as “reasonable” varies according to the field of activities, and remain a challenge in all cases.

Development of measurement methods and dose evaluating algorithms for electronic personal dosimeter

For personal radiation dose monitoring, electronic personal dosimeters (EPD), also known as active personal dosimeter (APD), using silicon diode detector have the advantage capability of measuring and displaying directly the exposure results of gamma, beta and neutron radiations in real time. They are mainly considered as good complement to passive dosimeters to satisfy ALARA principle in the radiation protection. In this paper, the meansurement methods and algorithms for evaluating personal dose equivalents such as Hp(10) and Hp(0.07) from air-kerma are studied and developed in two directions: the first, named energy correction method based on incident energy determined by the ratio of two detector responses with the different filter configurations; the second new method is carried out in the way that matching the shape of a detector’s energy response curve to the kerma-to-personal dose equivalent conversion function provides an approximate means of determining the dose equivalent without the need to resolve the actual incident energies. The algorithm has also been experimentally verified at Secondary Standards Dosimetry Laboratory (SSDL) of INST by the beam of radiation defined in ISO 4037-1. The obtained results of personal dose equivalents with errors almost less than 30% in energy range from 20 keV to 1.5 MeV are partially met the EPD design requirements according to the IEC 61526 Standard. The work and results of described in this paper are important basics for design and construction of completed electronic personal dosimeter.

Radiation safety requirements for training of users of diagnostic X-ray equipment in South Africa

Background. Globally, the aim of requirements regarding the use and ownership of diagnostic medical X-ray equipment is to limit radiation by abiding by the ‘as low as reasonably achievable’ (ALARA) principle. The ignorance of radiographers with regard to radiation safety requirements, however, is currently a cause of concern. The enhancement of the 4-year radiography curriculum leading to a Bachelor’s qualification provides an opportunity to explore the training and assessment to meet, among others, the ALARA principle, which addresses national and international concerns and criteria. Healthcare workers outside the scope of radiography, who are also considered radiation workers, may be even more ignorant and are therefore also implicated. The process of investigation included a contextualisation of the available regulation documents, the Delphi technique to determine the content of the training, and a questionnaire to test students’ knowledge before and after training. Objectives. To determine the content of the radiation safety requirements training and assessment to implement standardised teaching, learning activities and assessment to prepare radiographers as radiation workers well trained for practice. Methods. The content of the radiation safety requirements training was determined with the Delphi technique. Results. Consensus regarding the content of the radiography students’ training was reached and implemented. Furthermore, it guided the development of teaching and learning activities complemented by aligned assessment. Conclusion. Standardised education and assessment for radiation safety requirements have the potential to ensure that radiation safety regulations are implemented optimally in diagnostic imaging.

Assessment of Pediatrics Radiation Dose from Routine X-Ray Examination at Jimma University Hospital, Southwest Ethiopia.

Given the fact that children are more sensitive to ionizing radiation than adults, with an increased risk of developing radiation-induced cancer, special care should be taken when they undergo X-ray examinations. The main aim of the current study was to determine Entrance Surface Dose (ESD) to pediatric patients arising from routine x-ray examination in the Radiology Department of Jimma University Specialized Hospital (JUSH). Descriptive cross-sectional study was conducted on pediatric patients less than 15 years of age who visited to seek x-ray examinations in JUSH. In this study, chest (AP), skull (AP), Abdomen (AP) and Pelvic (AP) x-ray examinations were analyzed. Radiographic exposure factors were recorded in each examination. ESD was calculated using exposure parameters. The calculated ESD values were weighed against the Diagnostic Reference Level (DRL) recommended doses and similar published studies. Comparison was made among different age groups through mean comparison. The obtained ESD values were mostly higher than the values in internationally published studies and DRL for all age groups. For chest AP, the mean ESD values were 1.82mGy which is higher than similar studies in Nigeria (0.642Mgy), Brazil (o.o62mGy) and NRPB (0.050mGy) for ages of 0-1 years. The higher pediatric patient dose obtained in this study is a further indicator that doses delivered to pediatric patients are not according to ALARA principle, and there is a need to optimize service and patients' radiation exposure in JUSH in particular and in Ethiopia in general.

Radiation dose reduction in thoracic and lumbar spine instrumentation using navigation based on an intraoperative cone beam CT imaging system: a prospective randomized clinical trial.

Spine surgery still remains a challenge for every spine surgeon, aware of the potential serious outcomes of misplaced instrumentation. Though many studies have highlighted that using intraoperative cone beam CT imaging and navigation systems provides higher accuracy than conventional freehand methods for placement of pedicle screws in spine surgery, few studies are concerned about how to reduce radiation exposure for patients with the use of such technology. One of the main focuses of this study is based on the ALARA principle (as low as reasonably achievable). A prospective randomized trial was conducted in the hybrid operating room between December 2015 and December 2016, including 50 patients operated on for posterior instrumented thoracic and/or lumbar spinal fusion. Patients were randomized to intraoperative 3D acquisition high-dose (standard dose) or low-dose protocol, and a total of 216 pedicle screws were analyzed in terms of screw position. Two different methods were used to measure ionizing radiation: the total skin dose (derived from the dose-area product) and the radiation dose evaluated by thermoluminescent dosimeters on the surgical field. According to Gertzbein and Heary classifications, low-dose protocol provided a significant higher accuracy of pedicle screw placement than the high-dose protocol (96.1 versus 92%, respectively). Seven screws (3.2%), all implanted with the high-dose protocol, needed to be revised intraoperatively. The use of low-dose acquisition protocols reduced patient exposure by a factor of five. This study emphasizes the paramount importance of using low-dose protocols for intraoperative cone beam CT imaging coupled with the navigation system, as it at least does not affect the accuracy of pedicle screw placement and irradiates drastically less.

Radiation Exposure during Neurointerventional Procedures in Modern Biplane Angiographic Systems: A Single-Site Experience

Background and Purpose: Per the ALARA principle, reducing the dose delivered to both patients and staff must be a priority for endovascular therapists, who should monitor their own practice. We evaluated patient exposure to radiation during common neurointerventions performed with a recent flat-panel detector angiographic system and compared our results with those of recently published studies. Methods: All consecutive patients who underwent a diagnostic cerebral angiography or intervention on 2 modern flat-panel detector angiographic biplane systems (Innova IGS 630, GE Healthcare, Chalfont St Giles, UK) from February to November 2015 were retrospectively analyzed. Dose-area product (DAP), cumulative air kerma (CAK) per plane, fluoroscopy time (FT), and total number of digital subtraction angiography (DSA) frames were collected, reported as median (interquartile range), and compared with the previously published literature. Results: A total of 755 consecutive cases were assessed in our institution during the study period, including 398 diagnostic cerebral angiographies and 357 interventions. The DAP (Gy × cm²), fontal and lateral CAK (Gy), FT (min), and total number of DSA frames were as follows: 43 (33-60), 0.26 (0.19-0.33), 0.09 (0.07-0.13), 5.6 (4.2-7.5), and 245 (193-314) for diagnostic cerebral angiographies, and 66 (41-110), 0.46 (0.25-0.80), 0.18 (0.10-0.30), 18.3 (9.1-30.2), and 281 (184-427) for interventions. Conclusion: Our diagnostic cerebral angiography group had a lower median and was in the 75th percentile of DAP and FT when compared with the published literature. For interventions, both DAP and number of DSA frames were significantly lower than the values reported in the literature, despite a higher FT. Subgroup analysis by procedure type also revealed a lower or comparable DAP.

Assessment of Image Quality Parameters for Computed Tomography in Sudan

X-ray-computed tomography (CT) has become one of the most important investigation procedures worldwide. The study aimed to assess image quality parameters, mainly noise, and radiation doses during abdominal examination. This study examined the diagnostic parameters (kilo voltage, tube current time product, slice thickness, and pitch) and their effects on image quality as well as the radiation doses received from computed tomography scanners using phantom. The study carried out in four CT centers in Sudan. The study applied prospective and experimental methods. The study demonstrated there was a linear correlation between diagnostic parameters and image noise. The reduction in milli-ampere second and peak kilo voltage increased the image noise. Moreover increasing the pitch led to an increase in the image noise, whereas increasing the slice thickness, reduced the image noise. There was also a linear relationship between kilo voltage and radiation dose at Elnileen diagnostic center characterized by an increase kilo voltages values which led to an increase in the radiation dose by 92% and a reduction in the image noise by 83%. However, at Antalya medical center, increasing in kilo voltage values led to an increase in the radiation dose by 35% and a reduction in the image noise by 26%. Also increasing in milli-ampere second values led to an increase in the radiation dose by 49% and a reduction in the image noise by 46% in a phantom compared with an increase in radiation dose by 82% and a reduction in the image noise by 51% in patients .The study found that an optimal protocol for adult abdominal scan at Antalya medical center was 4.22HU for image noise and 10.45 mGy for radiation dose when using 120 kVp, 300 mAs, 5 mm slice thickness and pitch of 0.8. At Elnileen diagnostic center, however, the optimal protocol was 5.4 HU for image noise and 5.4 mGy for radiation dose using 130 kVp, 50 mAs, 10 mm slice thickness and pitch of 2. In addition, the quality control tests for image quality parameters carried out at the two centers were performed by using the Chat Phan phantom and all the tests were within the acceptable limits, according to Sudan Atomic Energy Commission (SAEC) Standardizations. The study concludes with a number of recommendations, such as; the necessity for an extensive collaboration among manufacturers, radiologists, technologists and physicists to find a plan to decrease patient radiation dose (ALARA Principle) from computed tomography scanner.