Significant Radiation Dose Research Articles

Comparing Fourth Generation Statistical Iterative Reconstruction Technique to Standard Filtered Back Projection in Pediatric Head Computed Tomography Examinations.

Although advanced statistical iterative reconstruction (IR) techniques are valued in pediatric computed tomography (CT) imaging, there is little published data on how these techniques affect image quality and radiation dose in the pediatric population. This is particularly true in the context of pediatric head CT examinations. This study analyzed the differences in image quality and several standard metrics of radiation dose on multidetector pediatric head CT examinations performed using standard filtered back projection (FBP) with reconstructions using iDose, a fourth-generation statistical iterative reconstruction technique. Using a retrospective review of 282 pediatric head CT examinations, we compared how iDose fared against FBP for effects on several standard metrics of radiation dose and qualitative and quantitative assessment of image quality. Our assessment revealed that examinations obtained using low-dose protocols reconstructed using iDose, when compared with standard-dose examinations reconstructed using FBP, resulted in significant radiation dose reduction while performing equally or better in quantitative image quality parameters. For most qualitative image quality parameters, the iDose group demonstrated equal performance to standard filtered back technique with a few notable exceptions. In the parameter of image sharpness in the 1.5 to 7 year olds, iDose fared better than FBP. However, FBP outperformed iDose in the qualitative parameters of decreased image graininess/noise in patients older than 13 years, improved image sharpness in patients aged between 7 and 13 years, and improved visibility of small parts for those aged 7 to 13 years. We conclude that iDose is effective at allowing significant radiation dose reduction while maintaining or, rarely, even improving quantitative image quality compared with FBP in the setting of pediatric head CT examinations. However, for certain qualitative image quality parameters in older-aged children, the use of iDose resulted in a poorer performance compared with FBP.

Subtraction CT angiography in head and neck with low radiation and contrast dose dual-energy spectral CT using rapid kV-switching technique.

To investigate the application of low radiation and contrast dose spectral CT angiology using rapid kV-switching technique in the head and neck with subtraction method for bone removal. This prospective study was approved by the local ethics committee.64 cases for head and neck CT angiology were randomly divided into Groups A (n = 32) and B (n = 32). Group A underwent unenhanced CT with 100kVp, 200mA and contrast-enhanced CT with spectral CT mode with body mass index-dependent low dose protocols. Group B used conventional helical scanning with 120kVp, auto mA for noise index of 12HU (Hounsfield unit)for both the unenhanced and contrast-enhanced CT. Subtraction images were formed by subtracting the unenhanced images from enhanced images (with the 65keV-enhanced spectral CT image in Group A). CT numbers and their standard deviations in aortic arch, carotid arteries, middle cerebral artery and air were measured in the subtraction images. The signal-to-noise ratio and contrast-to-noise ratio for the common and internal carotid arteries and middle cerebral artery were calculated. Image quality in terms of bone removal effect was evaluated by two experienced radiologists independently and blindly using a 4-point system. Radiation dose and total iodine load were recorded. Measurements were statistically compared between the two groups. The two groups had same demographic results. There was no difference in the CT number, signal-to-noise and contrast-to-noise ratio values for carotid arteries and middle cerebral artery in the subtraction images between the two groups (p > 0.05). However, the bone removal effect score [median (min-max)] in Group A [4 (3-4)] was rated better than in Group B [3 (2-4)] (p < 0.001), with excellent agreement between the two observers (κ>0.80). The radiation dose in Group A (average of 2.64 mSv) was 57% lower than the 6.18 mSv in Group B (p < 0.001). The total iodine intake in Group A was 13.5g, 36% lower than the 21g in Group B. Spectral CT imaging with rapid kV-switching in the subtraction angiography in head and neck provides better bone removal with significantly reduced radiation and contrast dose compared with conventional subtraction method. Advances in knowledge: This novel method provides better bone removal with significant radiation and contrast dose reduction compared with the conventional subtraction CT, and maybe used clinically to protect the thyroid gland and ocular lenses from unnecessary high radiation.

4:03 PM Abstract No. 78 Creation of an optimization process in a quaternary care academic institution leads to significant radiation dose reduction

4:03 PM Abstract No. 78 Creation of an optimization process in a quaternary care academic institution leads to significant radiation dose reduction

High-pitch low-voltage CT coronary artery calcium scoring with tin filtration: accuracy and radiation dose reduction.

To investigate diagnostic accuracy and radiation dose of high-pitch CT coronary artery calcium scoring (CACS) with tin filtration (Sn100kVp) versus standard 120kVp high-pitch acquisition. 78 patients (58% male, 61.5±9.1 years) were prospectively enrolled. Subjects underwent clinical 120kVp high-pitch CACS using third-generation dual-source CT followed by additional high-pitch Sn100kVp acquisition. Agatston scores, calcium volume scores, Agatston score categories, percentile-based risk categorization and radiation metrics were compared. 61/78 patients showed coronary calcifications. Median Agatston scores were 34.9 [0.7-197.1] and 41.7 [0.7-207.2] and calcium volume scores were 34.1 [0.7-218.0] for Sn100kVp and 35.7 [1.1-221.0] for 120kVp acquisitions, respectively (both p<0.0001). Bland-Altman analysis revealed underestimated Agatston scores and calcium volume scores with Sn100kVp versus 120kVp acquisitions (mean difference: 16.4 and 11.5). However, Agatston score categories and percentile-based risk categories showed excellent agreement (ĸ=0.98 and ĸ=0.99). Image noise was 25.8±4.4HU and 16.6±2.9HU in Sn100kVp and 120kVp scans, respectively (p<0.0001). Dose-length-product was 9.9±4.8mGy*cm and 40.9±14.4mGy*cm with Sn100kVp and 120kVp scans, respectively (p<0.0001). This resulted in significant effective radiation dose reduction (0.13±0.07mSv vs. 0.57±0.2mSv, p<0.0001) for Sn100kVp acquisitions. CACS using high-pitch low-voltage tin-filtered acquisitions demonstrates excellent agreement in Agatston score and percentile-based cardiac risk categorization with standard 120kVp high-pitch acquisitions. Furthermore, radiation dose was significantly reduced by 78% while maintaining accurate risk prediction. • Coronary artery calcium scoring with tin filtration reduces radiation dose by 78%. • There is excellent correlation between high-pitch Sn100kVp and standard 120kVp acquisitions. • Excellent agreement regarding Agatston score categories and percentile-based risk categorization was achieved. • No cardiac risk reclassifications were observed using Sn100kVp coronary artery calcium scoring.

Significant dose reduction is feasible in FDG PET/CT protocols without compromising diagnostic quality

PurposeTo reduce the radiation dose to patients by optimizing oncological FDG PET/CT protocols. MethodsThe baseline PET/CT protocol in our institution for oncological PET/CT examinations consisted of the administration of 5.18 MBq/kg of FDG and a CT acquisition with a reference current–time product of 120 mAs. In 2016, FDG activity was reduced to 4.44 and 3.70 MBq/kg and reference CT current–time-product was reduced to 100 and 80 mAs. 322 patients scanned with different protocols were retrospectively evaluated. For each patient, effective dose was calculated. The overall image quality was subjectively rated by the referring physician on a 4-point scale (IQ score: 1 excellent, 2 good, 3 poor but interpretable, 4 poor not interpretable). Image quality was quantitatively evaluated measuring noise in the liver. ResultsCT Results: Effective dose was progressively reduced from 9.5 ± 2.8 to 8.0 ± 2.3 and 6.2 ± 1.5 mSv (p < 0.001). A mean dose reduction of 34.9% was achieved. There was a significant degradation of IQ score (p < 0.05) and noise (p < 0.001). Nevertheless, the number of poor quality studies (IQ score >2) did not increase.PET Results: Effective dose was gradually reduced from 6.5 ± 1.4 to 5.7 ± 1.3 and 5.0 ± 1.0 mSv (p < 0.001). Average dose reduction was 23.4%. IQ score (p < 0.05) and noise (p < 0.001) significantly degraded for lower activity protocols. However, all images with reduced activity were scored as interpretable (IQ score ≤ 3). ConclusionsA significant radiation dose reduction of 28.7% was reached. Despite a slight reduction in image quality, the new regime was successfully implemented with readers reporting unchanged clinical confidence.

Radiation Dose Optimization in Interventional Cardiology: A Teaching Hospital Experience.

Radiological interventions play an increasingly relevant role in cardiology. Due to the inherent risks of ionizing radiation, proper care must be taken with monitoring and optimizing the dose delivered in angiograms to pose as low risk as possible to staff and patients. Dose optimization is particularly pertinent in teaching hospitals, where longer procedure times are at times necessary to accommodate the teaching needs of junior staff, and thus impart a more significant radiation dose. This study aims to analyze the effects of different protocol settings in routine coronary angiograms, from the perspective of a large tertiary center implementing a rapid dose reduction program. Routine coronary angiograms were chosen to compare baseline levels of radiation, and the dose imparted before and after dose optimization techniques was measured. Such methods included lowering dose per pulse, fluoroscopic pulse rates, and cine acquisition frame rates. The results showed up to 63% reduction in radiation dose without adverse impact on clinical or teaching outcomes. A 10 fps/low and 5 pps/low setting was found to achieve maximum dose optimization, with the caveat that settings require incremental changes to accommodate for patient complexities.

A comparison between low dose and standard dose computed tomography scan in detection of urolithiasis

Background: Computed tomography (CT) (standard and low-dose CT [LDCT] scan) has become the reference technique in medical imaging for urinary calculi, to diagnose, plan treatment, and explore differential diagnosis of renal colic. Objective: This study was done to compare the low-dose nonenhanced CT scan with standard dose CT scan in the detection of urolithiasis. Materials and Methods: Cross-sectional study conducted from 2017 to 2018 in Al-Hilla teaching general hospital on 60 patients undergone unenhanced (native) spectral detector CT (SDCT) and LDCT, the patients were scanned by Siemens CT system, 64 slice using automated tube current modulation, all CT scan were performed without oral or intravenous contrast. Results: This study showed that 93 stones detected by SDCT scan and 89 stones detected by LDCT scan, mean age of patients 44.2 ± 7.3 and mean of body mass index 26.3 ± 3.1, male constitute 56.6% (34) and female 43.4% (26). In 46.6% of patients had stone in the left side and 53.4% show stone in right side, most of patients presented solitary stone which appear 73.4%, 11.6% of patients had double stone, 5% had triple stone, 6.6% had four stones, and 3.45% had 5 or more stone at investigation, 10.8% of stones lie in ureter, 7.6% of stones in renal pelvis, 13.9% in upper calyx, 28% in lower calyx, and 39.7% lie in middle calyx, according to size of stones 11.9% of stones had size 20 mm. In standard CT scan, the current mean was 283.2 while in LDCT scan the mean was 126.1 mA, sensitivity is (93%) and specificity (100%) of LDCT in reference SDCT. Conclusion: LDCT scans provide effective methods of identifying and evaluating urinary tract stones, high diagnostic accuracy, sensitivity, and specificity are maintained despite significant radiation dose reduction compared to standard dose CT.

Low-dose noncontrast computed tomography in adults with acute appendicitis

Background: Computed tomography (CT) is now considered the imaging modality of choice for acute abdomen. However, with the increasing concern for exposure to ionizing radiation and its related risk of cancer in long run, low-dose CT has come up in recent studies with the attempt to minimize the effective radiation dose, yet giving the similar diagnostic yield. Aim: The aim of this study was to evaluate the diagnostic performance of low-dose noncontrast multidetector CT in adult patients with suspected acute appendicitis in relation to patients' body mass index. Materials and Methods: Eighty-three adult patients with suspected acute appendicitis were subjected to both standard and low-dose abdominal noncontrast CT (NCCT). The images were interpreted independently by two radiologists (blinded). Data collected were summarized and statistically analyzed. P Results: With low-dose NCCT abdomen, appendix was visualized in 80 patients (96.4%), with nonvisualization in 3 patients (3.6%), which was similar to standard dose. Low-dose NCCT has an overall sensitivity of 98.2% and a specificity of 100% in the diagnosis of acute appendicitis. Only one false-negative case and zero false-positive case was found, considering 6 mm as the cutoff value in appendiceal diameter with associated fat stranding. Alternative diagnoses were found in 22 (10 females and 12 males) patients. Conclusion: Low-dose NCCT abdomen was found highly accurate in diagnosing acute appendicitis with achievement of significant radiation dose reduction (about 88%) and thus can be recommended as a fast, safe, and cost-effective initial imaging technique in patients with right lower quadrant pain.

Measurements of natural radioactivity in infant formula and radiological risk assessment

A set of measurements have been conducted to determine the levels activity of gamma-emitters present in infant formula. The study of different samples shows the presence of the following radionuclides: 226Ra, 232Th and 40K with respectively average activity of 0.52 ± 0.087, 0.51 ± 0.062, 371.98 ± 3.68 Bq/kg. The mean annual doses lead to 0.62 and 0.24 mSv/year whereas the total risk is about 7.91 × 10−6 and 5.32 × 10−6 respectively ≤ 1 year and 1–2 years old infants. The obtained results show that no significant radiation dose and no risk to the infants due to consumption of these milks.

Reliable Radiation Technique to Minimize Ovarian Dose During Radiation Prophylaxis of Heterotopic Ossification.

Scattered radiation during radiotherapy (RT) directed at the hip joint poses concerns about ovarian function in patients of reproductive age. Here, we report the impact of using a split-beam technique (SBT) and different photon energies on the total ovary dose during radiation prophylaxis of heterotopic ossification (HO). This was a single-institution, retrospective study of 32-patients with traumatic acetabular fractures (TAF). All underwent surgery followed by CT-based-RT within 72 h in a single fraction of 700 cGy. Ipsilateral (IL) and contralateral (CL) ovaries (OV) were contoured separately and dose volume histograms (DVH) generated. Additional planning trials were created for each patient by utilizing a SBT medially and by using different photon energies (6-18 MV) to investigate the difference in ovary dose among these maneuvers. The median Mean-dose delivered to ILOV was 59 cGy and the median Max-dose was 177 cGy. CLOV median Mean-dose was 6 cGy and median Max-dose was 10 cGy. SBT at the medial edge of the field led to a 27% and 22% dose reduction in the median Mean and Max. doses, respectively, to ILOV; 9% and 5% reduction was seen in the median Mean and Max. doses, respectively, to CLOV. Higher photon energies (10-18 MV) led to an additional 28% and 16 % reduction in median Mean and Max. doses, respectively, to ILOV when compared to those from 6 MV. The CLOV median Mean dose was reduced by 18% and the Max. dose was reduced by 12%. A biologically significant radiation dose is delivered to the ovaries during HO radiation prophylaxis at the hip joints. Ipsilateral ovarian dose could be reduced by half and contralateral by one-quarter by using CT-based treatment planning with a medial SBT and photon energies above 6 MV. We suggest using no more than 10 MV to minimize neutron contamination. Those techniques should be the standard of care as it provides a reliable method for minimizing the radiation dose to the ovaries, consequently, maximizing female fertility preservation during HO radiation prophylaxis. All female patients in childbearing age should be fully informed about ovarian radiation exposure and possible temporary alteration in ova production and morphology.

A retrospective comparison of intraoperative CT and fluoroscopy evaluating radiation exposure in posterior spinal fusions for scoliosis

BackgroundRadiation exposure is a concern in the field of medicine. Deformity spine surgeons depend on modalities that have high exposure through scoliosis x-rays or computed tomography. The use of fluoroscopy has increased with the increased use of pedicle screws. Recently other 3-D imaging devices with navigation have also been brought onto the market to improve accuracy of screw placement. There is concern that because of the use of CT, the radiation dose to the patient is increased, however there is little literature that directly compares the amount of radiation using the 3-D devices to traditional fluoroscopy. Although we know intraoperative CT decreases the amount of radiation to the surgeon and operating room staff, there is limited comparison data for exposure to patients. Our study focused on a comparison of radiation exposure data for pediatric scoliosis patients receiving posterior spinal fusions using traditional fluoroscopy and the Medtronic O-arm in an effort to determine the method most likely to decrease radiation exposure in the pediatric population.MethodsRetrospective review of data in patient charts from two pediatric surgeons practicing in both a University and private hospital setting. Data collected included age, weight, height, diagnosis, Cobb angle, fusion levels, number of screws, and number of hooks, O-arm spins, fluoro doses and O-arm doses. Effective dose was calculated using output measures and radiation doses were compared along a continuum that took into account the amount of correction as indicated by Cobb angle.ResultsA total of 57 patients, 25 using the O-arm and 32 using traditional fluoroscopy, were analyzed. Effective dose was calculated and then compared as a factor correlated to curve severity. At lower angles of correction we found no statistically significant difference between methods in terms of effective radiation dose. There was no statistically significant divergence until a Cobb angle correction of greater than 74 degrees, where the Oarm dose was shown to be lower by comparison.ConclusionWe found that regardless of the methods used there is still a significant radiation dose that is utilized in scoliosis procedures. The two methods analyzed did not display statistically significant differences in effective dose for the average case. Safely managing radiation exposure for pediatric patients is of the utmost priority. Healthcare professionals, however, face repeated exposure to radiation over the course of a long career. In our data set the O-Arm system does not increase overall exposure for patients and decreases radiation doses for providers and thereby provides a safe alternative to traditional fluoroscopy without compromising accuracy of implant placement or patient care.Level of Evidence: III.

Unindicated multiphase CT scans in non-traumatic abdominal emergencies for women of reproductive age: a significant source of unnecessary exposure.

To determine the frequency of unindicated CT phases and the resultant excess of absorbed radiation doses to the uterus and ovaries in women of reproductive age who have undergone CT for non-traumatic abdomino-pelvic emergencies. We reviewed all abdomino-pelvic CT examinations in women of reproductive age (40years or less), between 1 June 2012 and 31 January 2015. We evaluated the appropriateness of each CT phase on the basis of clinical indications, according to ACR appropriateness criteria and evidence-based data from the literature. The doses to uterus and ovaries for each phase were calculated with the CTEXPO software, taking into consideration the size-specific dose estimate (SSDE) after measuring the size of every single patient. The final cohort was composed of 76 female patients with an average age of 30 (from 19 to 40 years). In total, 197 CT phases were performed with an average of 2.6 phases per patient. Out of these, 93 (47%) were unindicated with an average of 1.2 inappropriate phases per patient. Unindicated scans were most frequent for appendicitis and unlocalized abdominal pain. The excesses of mean radiation doses to the uterus and ovaries due to unindicated phases were, respectively, of 38 and 33mSv per patient. In our experience, unindicated additional CT phases were numerous with a significant excess radiation dose without an associated clinical benefit. This excess of radiation could have been avoided by widespread adoption of the ACR appropriateness criteria and evidence-based data from the literature.

THE FACTOR OF IONIZING RADIATION AND THYROID CANCER IN WOMEN IN THE ALTAI KRAI

The purpose of the study was to study the dynamics of the incidence of thyroid cancer in the female population of the Altai Territory during the period of 1992-2016. Studies were performed with the use of data of the patient register of thyroid cancer, including information on 3026 women, with the use of methods of modern medical statistics. Intensive and standardized indices were calculated for the female population, resided near to traces of nuclear explosions executed at the Semipalatinsk test site, in the zone of the most significant radiation doses (the Main group). As a comparison, incidence rates of the remaining population of the Altai Territory (the Comparison group) and average values for the region were used. The article presents results of a descriptive epidemiological study of the incidence of thyroid cancer in the Altai Territory over 25 years (1992-2016). The results of the probabilistic association of the incidence of thyroid cancer with the ionizing radiation factor due to nuclear tests at the Semipalatinsk test site were obtained. The dynamics of the incidence of thyroid cancer by the data for five-years periods (averaged data): 1992-1996; 1997-2001; 2002-2006; 2007-2011 and 2012-2016 was studied in various territories of the Altai Territory: both on the traces of nuclear explosions - the main group, and in the rest territory (the comparison group), indices of average values for the regions. There were revealed the dynamics of the incidence of thyroid cancer in tens of years after nuclear tests in the population living in the zone with the most significant doses of radiation and its gradual decrease, due to rehabilitation measures. New approaches to the formation of high cancer risk groups for thyroid cancer in the Altai Territory are substantiated.

Buccal mucosa micronuclei counts in relation to exposure to low dose-rate radiation from the Chornobyl nuclear accident and other medical and occupational radiation exposures

BackgroundIonizing radiation is a well-known carcinogen. Chromosome aberrations, and in particular micronuclei represent an early biological predictor of cancer risk. There are well-documented associations of micronuclei with ionizing radiation dose in some radiation-exposed groups, although not all. That associations are not seen in all radiation-exposed groups may be because cells with micronuclei will not generally pass through mitosis, so that radiation-induced micronuclei decay, generally within a few years after exposure.MethodsBuccal samples from a group of 111 male workers in Ukraine exposed to ionizing radiation during the cleanup activities at the Chornobyl nuclear power plant were studied. Samples were taken between 12 and 18 years after their last radiation exposure from the Chornobyl cleanup. The frequency of binucleated micronuclei was analyzed in relation to estimated bone marrow dose from the cleanup activities along with a number of environmental/occupational risk factors using Poisson regression adjusted for overdispersion.ResultsAmong the 105 persons without a previous cancer diagnosis, the mean Chornobyl-related dose was 59.5 mSv (range 0–748.4 mSv). There was a borderline significant increase in micronuclei frequency among those reporting work as an industrial radiographer compared with all others, with a relative risk of 6.19 (95% CI 0.90, 31.08, 2-sided p = 0.0729), although this was based on a single person. There was a borderline significant positive radiation dose response for micronuclei frequency with increase in micronuclei per 1000 scored cells per Gy of 3.03 (95% CI -0.78, 7.65, 2-sided p = 0.1170), and a borderline significant reduction of excess relative MN prevalence with increasing time since last exposure (p = 0.0949). There was a significant (p = 0.0388) reduction in MN prevalence associated with bone X-ray exposure, but no significant trend (p = 0.3845) of MN prevalence with numbers of bone X-ray procedures.ConclusionsThere are indications of increasing trends of micronuclei prevalence with Chornobyl-cleanup-associated dose, and indications of reduction in radiation-associated excess prevalence of micronuclei with time after exposure. There are also indications of substantially increased micronuclei associated with work as an industrial radiographer. This analysis adds to the understanding of the long-term effects of low-dose radiation exposures on relevant cellular structures and methods appropriate for long-term radiation biodosimetry.

Precision and accuracy of consumer-grade motion tracking system for pedicle screw placement in pediatric spinal fusion surgery

Adolescent idiopathic scoliosis (AIS) is a 3-dimensional spinal deformity involving lateral curvature and axial rotation. Surgical intervention involves insertion of pedicle screws into the spine, requiring accuracies of 1mm and 5° in translation and rotation to prevent neural and vascular complications. While commercial CT-navigation is available, the significant cost, bulk and radiation dose hinders their use in AIS surgery. The objective of this study was to evaluate a commercial-grade Optitrack Prime 13W motion capture cameras to determine if they can achieve adequate accuracy for screw insertion guidance in AIS. Static precision, camera and tracked rigid body configurations, translational and rotational accuracy were investigated. A 1-h camera warm-up time was required to achieve precisions of 0.13mm and 0.10°. A three-camera system configuration with cameras at equal height but staggered depth achieved the best accuracy. A triangular rigid body with 7.9mm markers had superior accuracy. The translational accuracy for motions up to 150mm was 0.25mm while rotational accuracy was 4.9° for rotations in two directions from 0° to 70°. Required translational and rotational accuracies were achieved using this motion capture system as well as being comparable to surgical-grade navigators.

Factors influencing radiation exposure during internal fixation of hip fractures

The use of fluoroscopy is of great importance for operative fixation of fractures. Previous studies have shown an increased fluoroscopy time for intramedullary nails and with junior surgeons in comparison with more experienced surgeons. We examined the impact of operation length on fluoroscopy dose, cumulative fluoroscopy time between consultant and registrar surgeons and cumulative fluoroscopy time between dynamic hip screw and intramedullary nailing. We performed a retrospective cohort study of all patients admitted to our centre over the period of 1year. Patients who underwent dynamic hip screw (DHS) or intramedullary (IM) nailing were identified from our in-hospital hip fracture database. Intraoperative fluoroscopy images were then accessed through our hospital's medical imaging software. A total of 137 patients were identified. Fluoroscopy reports were not available for 49 patients, resulting in a final total of 88 patients. Patients whose operation lasted longer than 1h received a statistically significant higher dose of radiation (183.83 cGYM2 vs. 368.22 cGYM2; p value 0.0002). Operations performed by a consultant resulted in less cumulative fluoroscopy time in comparison with those performed by a registrar or specialist registrar although this was not statistically significant (00:00:53 vs. 00:00:45; p vaue 0.38). Cumulative fluoroscopy time was less in dynamic hip screw compared to long intramedullary nails (00:00:39 vs. 00:01:29; p value <0.001) and short intramedullary nails (00:00:39 vs. 00:01:52; p value 0.387). Studies, which had a cumulative fluoroscopy time exceeding 50 secs, delivered a higher radiation dose (434.34cGYM2 vs. 150.51cGYM2; p value <0.001). We concluded that there is no significant impact in cumulative fluoroscopy time in operations performed by either a registrar or consultant. Dynamic hip screws have a lower fluoroscopy time in comparison with long intramedullary nails.

Entrance surface dose and induced DNA damage in blood lymphocytes of patients exposed to low-dose and low-dose-rate X-irradiation during diagnostic and therapeutic interventional radiology procedures

The ionizing radiation received by patients and health workers due to radiological imaging may increase the risks of radiation effects, such as cancer and cataracts. We have investigated the dose received by specific areas around the head and related this to DNA damage in the blood lymphocytes of subjects exposed to interventional imaging. The entrance surface doses (ESD) to the forehead, neck, and shoulder were measured with a thermoluminescence dosimeter (CaSO4 disc or polycrystalline powder of lithium tetraborate doped with Mn) and compared with that of dose area product (DAP). DNA damage was measured by γ-H2AX, p53ser15, chromosomal aberration (CA), and micronucleus (MN) assays in lymphocytes of patients (n=75), before and 2 and 24h after exposure. The measured ESD values were 230.5±4.9, 189.5±3.55 and 90.7±3.4mGy for the forehead, neck, and shoulder, respectively. The DAP varied from 1.8 to 2047 Gy*cm2, showing a correlation with fluoroscopy time (r=0.417). Received doses did not increase early markers of DNA damage (γ-H2AX and p53ser15 assays), but residual damage (CA and MN frequencies) showed a significant (p<0.001) increase at 2 and 24h post-exposure compared to pre-imaging, despite poor correlation with DAP (r=0.1). Our results show that interventional imaging procedures deliver significant radiation doses and induce measurable DNA damage in lymphocytes of subjects, highlighting the need for rigorous patient safety protocols.

Biological mechanisms of radiation effects

Exposure to ionizing radiation for diagnostic purposes is inevitable in modern medicine. The therapeutic application of irradiation is highly effective against cancer; however, this implies exposure of normal tissue structures to significant doses of radiation. Diagnostic or therapeutic exposure to ionizing radiation can result in tissue changes and tumor induction in the long term. Knowledge of the biological mechanisms underlying these effects is essential for individualization of the application. This article examines the biological mechanisms at the tissue and molecular level, the clinical manifestation of radiation effects, dose-dependence of the risk and the temporal progression as well as influencing factors. The time course of the reaction of tissues to radiation exposure extends over wide ranges up to many decades. The effects of radiation on tissues are classified into early and late and their pathobiology is significantly different. Various factors (R) influencing the clinical manifestation of radiation effects have been identified related to the exposure pattern. The radiation tolerance of normal tissue structures regarding the induction of functional deficits shows great variation but always has athreshold value, which is usually not exceeded in diagnostic procedures. The risk of a radiation-induced fatal malignancy (total body exposure 5%/Gy) for amedical administration of radiation must be considered as very low in comparison to the natural risks. Informed consent of patients must reflect this in abalanced way.

Improved image quality with simultaneously reduced radiation exposure: Knowledge-based iterative model reconstruction algorithms for coronary CT angiography in a clinical setting

BackgroundThe aim of this study was to assess the potential for radiation dose reduction using knowledge-based iterative model reconstruction (K-IMR) algorithms in combination with ultra-low dose body mass index (BMI)-adapted protocols in coronary CT angiography (coronary CTA). MethodsForty patients undergoing clinically indicated coronary CTA were randomly assigned to two groups with BMI-adapted (I: <25.0 kg/m2, II: <28.0 kg/m2, III: <30.0 kg/m2, IV: ≥30.0 kg/m2) low dose (LD, I: 100kVp/75 mAs, II: 100kVp/100 mAs, III: 100kVp/150 mAs, IV: 120kVp/150 mAs, n = 20) or ultra-low dose (ULD, I: 100kVp/50 mAs, II: 100kVp/75 mAs, III: 100kVp/100 mAs, IV: 120kVp/100 mAs, n = 20) protocols. Prospectively-triggered coronary CTA was performed using a 256-MDCT with the lowest reasonable scan length. Images were generated with filtered back projection (FBP), a noise-reducing hybrid iterative algorithm (iD, levels 2/5) and K-IMR using cardiac routine (CR) and cardiac sharp settings, levels 1–3. ResultsGroups were comparable regarding anthropometric parameters, heart rate, and scan length. The use of ULD protocols resulted in a significant reduction of radiation exposure (0.7 (0.6–0.9) mSv vs. 1.1 (0.9–1.7) mSv; p < 0.02). Image quality was significantly better in the ULD group using K-IMR CR 1 compared to FBP, iD 2 and iD 5 in the LD group, resulting in fewer non-diagnostic coronary segments (2.4% vs. 11.6%, 9.2% and 6.1%; p < 0.05). ConclusionsThe combination of K-IMR with BMI-adapted ULD protocols results in significant radiation dose savings while simultaneously improving image quality compared to LD protocols with FBP or hybrid iterative algorithms. Therefore, K-IMR allows for coronary CTA examinations with high diagnostic value and very low radiation exposure in clinical routine.

Variability of radiation doses of cardiac diagnostic imaging tests: the RADIO-EVINCI study (RADIationdOse subproject of the EVINCI study)

BackgroundPatients with coronary artery disease can accumulate significant radiation dose through repeated exposures to coronary computed tomographic angiography, myocardial perfusion imaging with single photon emission computed tomography or positron emission tomography, and to invasive coronary angiography. Aim of the study was to audit radiation doses of coronary computed tomographic angiography, single photon emission computed tomography, positron emission tomography and invasive coronary angiography in patients enrolled in the prospective, randomized, multi-centre European study–EVINCI (Evaluation of Integrated Cardiac Imaging for the Detection and Characterization of Ischemic Heart Disease).MethodsWe reviewed 1070 tests (476 coronary computed tomographic angiographies, 85 positron emission tomographies, 310 single photon emission computed tomographies, 199 invasive coronary angiographies) performed in 476 patients (mean age 60 ± 9 years, 60% males) enrolled in 12 centers of the EVINCI. The effective doses were calculated in milli-Sievert (mSv) as median, interquartile range (IQR) and coefficient of variation of the mean.ResultsCoronary computed tomographic angiography (476 exams in 12 centers) median effective dose was 9.6 mSv (IQR = 13.2 mSv); single photon emission computed tomography (310 exams in 9 centers) effective dose was 9.3 (IQR = 2.8); positron emission tomography (85 in 3 centers) effective dose 1.8 (IQR = 1.6) and invasive coronary angiography (199 in 9 centers) effective dose 7.4 (IQR = 7.3). Inter-institutional variability was highest for invasive coronary angiography (100%) and coronary computed tomographic angiography (54%) and lowest for single photon emission computed tomography (20%). Intra-institutional variability was highest for invasive coronary angiography (121%) and coronary computed tomographic angiography (115%) and lowest for single photon emission computed tomography (14%).ConclusionCoronary computed tomographic angiography and invasive coronary angiography doses vary substantially between and within centers. The variability in nuclear medicine procedures is substantially lower. The findings highlight the need to audit doses, to track cumulative exposures and to standardize doses for imaging techniques.Trial registrationThe study protocol is available at https://www.clinicaltrials.gov/ (ClinicalTrials.gov Identifier: NCT00979199). Information provided on September 16, 2009.