Effective Dose Conversion Factors Research Articles

Evaluation of radiation dose and radiation-induced cancer risk associated with routine CT scan examinations

Using patient-specific data, the present study aimed to identify organ and effective dose to estimate the lifetime attributable risks (LARs) of cancer incidence and mortality associated with routine CT procedures. A cross-sectional investigation was conducted on 515 patients who underwent CT scan. The effective dose was computed using two methods: first, the ImPACT software and relevant conversion factors. Second, the effective dose was determined using the scanner-derived DLP and AAPM TG 23's conversion factor. Using the biological effects of ionizing radiation (BEIR VII) report, LAR of cancer incidence and mortality were computed. The greatest mean organ doses for abdomen-pelvis, routine chest, chest HRCT, brain, and sinus examinations were 20.64 ± 3.27 mGy (kidneys), 21.55 ± 5.47 mGy (thymus and esophagus), 10.51 ± 1.31 mGy (thymus and esophagus), 22.72 ± 3.01 mGy (lens), and 18.56 ± 1.25 mGy (lens) respectively. Using ImPACT dosimetry software, the mean effective dose for routine chest, abdomen-pelvis, HRCT chest, brain, and sinus examinations was 8.46 mSv, 10.13 mSv, 4.19 mSv, 1 mSv, and 0.68 mSv, respectively. Using the DLP to effective dose conversion factor, the mean effective dose was lower. The mean cancer incidence risks per 100,000 people were 63.33, 54.98, 27.82, 6.31, and 5.22 for abdomen-pelvis, routine chest, HRCT, brain, and sinus examinations, respectively. The mean LAR of cancer mortality for all cancer was 38.22, 33.17, 16.72, 3.87, 2.93 for abdomen-pelvis, routine chest, HRCT, brain, and sinus examinations, respectively, per 100,000 people. Thus, CT scan exams are connected with a non-negligible risk of cancer, and patient radiation dose must be optimized to limit radiation risk.

Patient-specific Effective Dose Estimation from Dose-Length Product in Lung Computed Tomography Using Monte Carlo Simulation.

Computed tomography (CT) imaging has a large portion in the dose of patients from radiological procedures; therefore, accurate calculation of radiation risk estimation in this modality is inevitable. In this study, a method for determining the patient-specific effective dose using the dose-length product (DLP) index in lung CT scan using Monte Carlo (MC) simulation is introduced. EGSnrc/BEAMnrc MC code was used to simulate a CT scanner. The DOSxyznrc simulation code was used to simulate a specific voxelized phantom from the patient's lungs and irradiate it according to X-ray parameter of routing lung CT scan, and dose delivered to thorax organs was calculated. Three types of phantoms were simulated according to three different body habits (slim, standard, and fat patients) in two groups of men and women. A factor was used to convert the relative dose per particle in MC code to the absolute dose. The dose was calculated in all lung organs, and the effective dose was calculated for all three groups of patient body habits. DLP index and volume CT dose index (CTDIvol) were extracted from the patient's dose report in the CT scanner. The DLP to effective dose conversion factor (k-factor) for patients with different body habitus was calculated. Lung radiation dose in slim, standard, and fat patients in men was 0.164, 0.103, and 0.078 mGy/mAs and in women was 0.164, 0.105, and 0.079 mGy/mAs, respectively. The k-factor in the group of slim patients, especially in women, was higher than in other groups. CT scan dose indexes for slim patients are reported to be underestimated in studies. The dose report in CT scan systems should be modified in proportion to the patient's body habitus, to accurately estimate the radiation risk.

Presentation of Organ Dose and Effective Dose Conversion Factors in Dual-Energy Computed Tomography: A Monte Carlo Simulation Study.

The same conversion factors (k-factors) of Single CT (SECT) are applied to estimate the Effective Dose (ED) in Dual Energy Computed Tomography (DECT). However, k-factors for different organs need independently validating for DECT, due to the different conditions in DECT. This study aimed to calculate organ dose and k-factors in different imaging protocols (liver, chest, cardiac, and abdomen) for male and female phantoms. This Monte Carlo Simulation study used Monte Carlo N-Particle (MCNP) code for modeling a Siemens Somatom Definition Flash dual-source CT scanner. The organ dose, dose length product, and k-factors were calculated for the Medical Internal Radiation Dose (MIRD) of male and female phantoms. For the male phantom, the k-factors for the liver, chest, cardiac, and abdomen-pelvis imaging protocols are equal to 0.020, 0.012, 0.016, and 0.014 mSv.mGy-1cm-1, respectively. For the female phantom, the corresponding values are equal to 0.026, 0.023, 0.036, and 0.018, respectively. These values for DECT are different from those corresponding values for SECT, especially for the female phantom. The calculated k-factors for DECT can be used as reference values for the estimation of ED in DECT.

Use of secondary air kerma from dose area product and fluoroscopy time for preventive effective dose estimation in interventional radiology procedures for staff

Introduction: interventional radiology workers are potentially exposed to high levels of ionizing radiation, therefore preventive dose estimation is mandatory for the correct risk classification of staff. Effective dose (ED) is a radiation protection quantity strictly related to the secondary air kerma (K S), using appropriate multiplicative conversion factors (ICRP 106). The aim of this work is to evaluate the accuracy of K S estimated from physically measurable quantities such as dose-area product (DAP) or fluoroscopy time (FT). Methods: radiological units (n = 4) were characterized in terms of primary beam air kerma and DAP-meter response, consequently defining a DAP-meter correction factor (CF) for each unit. K S, scattered from an anthropomorphic phantom and measured by a digital multimeter, was then compared with the value estimated from DAP and FT. Different combinations of tube voltages, field sizes, current and scattering angles were used to simulate the variation of working conditions. Further measurements were performed to estimate the couch transmission factor for different phantom placements on the operational couch, defining a CF as the mean transmission factor. Results: when no CFs were applied, the measured K S showed a median percentage difference of between 33.8% and 115.7% with respect to K S evaluated from DAP, and between −46.3% and 101.8% for K S evaluated from FT. By contrast, when previously defined CFs were applied to the evaluated K S, the median percentage difference between the measured K S and the value evaluated from DAP ranged from between −7.94% and 15.0%, and between −66.2% and 17.2% for that evaluated from FT. Conclusion: when appropriate CF are applied, the preventive ED estimation from the median DAP value seems to be more conservative and easier to obtain with respect to the one obtained from the FT value. Further measurements should be performed with a personal dosimeter during routine activities to assess the proper K S to ED conversion factor.

Monitoring cone-beam CT radiation dose levels in a University Hospital.

To present patient dose levels for different CBCT scanners, acquired by a dose monitoring tool in a University Hospital, as a function of field of view (FOV), operation mode, and patient age. An integrated dose monitoring tool was used to collect radiation exposure data [type of CBCT unit, dose-area product (DAP), FOV size, and operation mode] and patient demographic information (age, referral department) performed on a 3D Accuitomo 170 and a Newtom VGI EVO unit. Effective dose conversion factors were calculated and implemented into the dose monitoring system. For each CBCT unit, the frequency of examinations, clinical indications, and effective dose levels were obtained for different age and FOV groups, and operation modes. A total of 5163 CBCT examinations were analyzed. Surgical planning and follow-up were the most frequent clinical indications. For the standard operation mode, effective doses ranged from 35.1 to 300 µSv and 9.26-117 µSv using 3D Accuitomo 170 and Newtom VGI EVO, respectively. In general, effective doses decreased with increasing age and FOV size reduction. Effective dose levels varied notably between systems and operation modes.Operation mode selection and FOV size were indication-oriented, with larger FOV sizes election serving surgical planning and follow-up. Seeing the influence of FOV size on effective dose levels, manufacturers could be advised to move toward patient-specific collimation and dynamic FOV selection. Systematically monitoring patient doses could be recommended for steering future CBCT optimization.

Development of deep learning-assisted overscan decision algorithm in low-dose chest CT: Application to lung cancer screening in Korean National CT accreditation program.

We propose a deep learning-assisted overscan decision algorithm in chest low-dose computed tomography (LDCT) applicable to the lung cancer screening. The algorithm reflects the radiologists' subjective evaluation criteria according to the Korea institute for accreditation of medical imaging (KIAMI) guidelines, where it judges whether a scan range is beyond landmarks' criterion. The algorithm consists of three stages: deep learning-based landmark segmentation, rule-based logical operations, and overscan determination. A total of 210 cases from a single institution (internal data) and 50 cases from 47 institutions (external data) were utilized for performance evaluation. Area under the receiver operating characteristic (AUROC), accuracy, sensitivity, specificity, and Cohen's kappa were used as evaluation metrics. Fisher's exact test was performed to present statistical significance for the overscan detectability, and univariate logistic regression analyses were performed for validation. Furthermore, an excessive effective dose was estimated by employing the amount of overscan and the absorbed dose to effective dose conversion factor. The algorithm presented AUROC values of 0.976 (95% confidence interval [CI]: 0.925-0.987) and 0.997 (95% CI: 0.800-0.999) for internal and external dataset, respectively. All metrics showed average performance scores greater than 90% in each evaluation dataset. The AI-assisted overscan decision and the radiologist's manual evaluation showed a statistically significance showing a p-value less than 0.001 in Fisher's exact test. In the logistic regression analysis, demographics (age and sex), data source, CT vendor, and slice thickness showed no statistical significance on the algorithm (each p-value > 0.05). Furthermore, the estimated excessive effective doses were 0.02 ± 0.01 mSv and 0.03 ± 0.05 mSv for each dataset, not a concern within slight deviations from an acceptable scan range. We hope that our proposed overscan decision algorithm enables the retrospective scan range monitoring in LDCT for lung cancer screening program, and follows an as low as reasonably achievable (ALARA) principle.

Patient radiation dose and lifetime attributable risk of cancer due to ionizing radiation in cardiovascular interventional radiological procedures

The aim of this study is to calculate the patient radiation dose and Lifetime Attributable Risk (LAR) in Cardiovascular Interventional Radiological (CVIR) procedures. The patient population included 327 patients who underwent Coronary Angiography (CA) and Percutaneous Coronary Interventions (PCI). Exposure data were reported for every examination such as Kerma-Area Product (KAP), fluoroscopy time and number of exposures. Organ dose and effective dose were assessed by PCXMC software. LAR values were determined according to BEIR VII report. The mean effective dose per examination in CA is 12.6 mSv for males and 10.25 mSv for females. In PCI, the mean effective dose is 18.06 mSv for males and 22.73 mSv for females. Organs with highest dose are thymus, heart, breast, and lung. The mean of LAR value in CA is 62 and 60 for males and females, respectively. In PCI, the mean of LAR value is 89 and 132 for males and females, respectively. Also, the KAP to effective dose conversion factors (CFKAP-ED) were calculated. CFKAP-ED for CA is 0.249 in males and 0.228 in females, and for PCI is 0.2446 and 0.2316 for males and females, respectively. This study will help better understand the concept of ionizing radiation dose in the CVIR procedures and how the individual patient’s effective dose and LAR can evaluate the cancer risk.

Assessment of Organ and Effective Doses Received by Paediatric Patients Undergoing Computed Tomography Examinations in Three Hospitals in Brazzaville, Congo Republic: An Urgent Necessity for Regulatory Control

The present study aimed at estimating organ and effective doses from computed tomography (CT) scans of paediatric patients in three hospitals in Brazzaville, Congo Republic. A total of 136 data on paediatric patients, from 0.25 (3 months) to 15 years old, who underwent head, chest, abdomen – pelvis (AP) and chest – abdomen – pelvis (CAP) CT scans was considered. The approach followed in the present study to compute organ doses was to use pre-calculated volume CT dose index (CTDIvol) – and 100 milliampere-second (mAs) – normalized organ doses determined by Monte Carlo (MC) simulation. Effective dose were then derived using the international commission on radiological protection (ICRP) publications 60 and 103 formalism. For comparison purposes, effective dose were also computed using dose-length product (DLP) – to – effective dose conversion factors. A relatively high variation in organ and effective doses was observed in each age group due to the dependence of patient dose on the practice of technicians who perform the CT scan within the same facility or from one facility to another, patient size and lack of adequate training of technicians. In the particular case of head scan, the brain and the eye lens were delivered maximum absorbed doses of 991.81 mGy and 1176.51 mGy, respectively (age group 10-15 y). The maximum absorbed dose determined for the red bone marrow was 246.08 mGy (age group 1-5 y). This is of concern as leukaemia and brain tumours are the most common childhood cancers and as the ICRP recommended absorbed dose threshold for induction of cataract is largely exceeded. Effective doses derived from MC calculations and ICRP publications 60 and 103 tissues weighting factors showed a 0.40-17.61 % difference while the difference between effective doses derived by the use of k- factors and those obtained by MC calculations ranges from 0.06 to 224.87 %. The study has shown that urgent steps should be taken in order to significantly reduce doses to paediatric patients to levels observed in countries where dose reduction techniques are successfully applied.

Radon Levels of Water Sources in the Southwest Coastal Region of Peninsular Malaysia

Across populations, the dominating source of public exposure to radiation is radon gas. In the present study, we aimed at determining the concentration of radon in water sources from the southwest coastal region of Peninsular Malaysia. A total of 27 water samples were taken from various water sources which included groundwater, as well as hot spring, lake, river, seawater, and tap water; the radon concentrations were measured using a RAD7 portable radon detector. The radon concentrations ranged from 0.07 ± 0.12 to 187 ± 12 Bq l−1, with an average of 21 ± 12 Bq l−1. The highest concentration was found in hot spring water, with an average concentration of 99 ± 6 Bq l−1, while the lowest concentration was found in tap water, with an average concentration of 1.95 ± 0.61 Bq l−1. The average concentrations of radon for all categories of sampled water were below the 100 Bq l−1 WHO guidance level for safe drinking water. According to the ICRP effective dose conversion factor and UNSCEAR (2000), the total effective dose from the summation of inhaled and imbibed water was calculated from the aqueous radon concentrations, with an average effective dose of 4.45 µSv y−1, well within the WHO safe drinking water guideline value of 100 µSv per year. The results of this study could support the efforts of authorities and regulators who are responsible for controlling and strategizing to ensure public safety against radon exposures.

A review of dental cone-beam CT dose conversion coefficients.

The purpose of this study was to review the literature to examine the usage and magnitude of effective dose conversion factors (DCE) for dental cone beam CT (CBCT) scanners. A PubMed literature search for publications relating to radiation dosimetry in dental radiography was performed. Papers were included if they reported DCE, or reported ICRP 103 effective dose and dose-area product. 71 papers relating to dental CBCT dosimetry were found, of which eight reported effective dose conversion factors or provided enough information to calculate dose conversion factors. Scanner model, effective dose, dose-area product, tube voltage, field of view size and DCE were extracted from the papers for analysis. DCE values ranged from 0.035 to 0.31 µSv/mGy-cm2 with a mean of 0.129 µSv/mGy-cm2 (SD = 0.056). When categorized into small (<100 cm2), medium (100-225 cm2) and large (>225 cm2) fields of view (FOV), linear fits to the effective dose and dose-area product yielded slopes of 0.129, 0.111 and 0.074 µSv/mGy-cm2 for small, medium and large FOVs respectively. The range of reported DCE values and spread with respect to field of view category suggests that DCE values that depend on FOV would provide more accurate effective dose estimates. Tube voltage was found to be a smaller factor in determining DCE. Reasonable values for DCE taking into account FOV size were obtained. There is considerable room for more work to be done to examine the behaviour of DCE with changes to patient age and dental CBCT imaging parameters.

Development of CT Effective Dose Conversion Factors from Clinical CT Examinations in the Republic of Korea

The aim of this study was to determine the conversion factors for the effective dose (ED) per dose length product (DLP) for various computed tomography (CT) protocols based on the 2007 recommendations of the International Commission on Radiological Protection (ICRP). CT dose data from 369 CT scanners and 13,625 patients were collected through a nationwide survey. Data from 3793 patients with a difference in height within 5% of computational human phantoms were selected to calculate ED and DLP. The anatomical CT scan ranges for 11 scan protocols (adult-10, pediatric-1) were determined by experts, and scan lengths were obtained by matching scan ranges to computational phantoms. ED and DLP were calculated using the NCICT program. For each CT protocol, ED/DLP conversion factors were calculated from ED and DLP. Estimated ED conversion factors were 0.00172, 0.00751, 0.00858, 0.01843, 0.01103, 0.02532, 0.01794, 0.02811, 0.02815, 0.02175, 0.00626, 0.00458, 0.00308, and 0.00233 mSv∙mGy−1∙cm−1 for the adult brain, intra-cranial angiography, C-spine, L-spine, neck, chest, abdomen and pelvis, coronary angiography, calcium scoring, aortography, and CT examinations of pediatric brain of <2 years, 4–6 years, 9–11 years, and 13–15 years, respectively. We determined ED conversion factors for 11 CT protocols using CT data obtained from a nationwide survey in Korea and Monte Carlo-based dose calculations.

Combining Optimized Image Processing With Dual Axis Rotational Angiography: Toward Low-Dose Invasive Coronary Angiography.

BackgroundDual axis rotational coronary angiography (DARCA) reduces radiation exposure during coronary angiography on older x‐ray systems. The purpose of the current study is to quantify patient and staff radiation exposure using DARCA on a modality already equipped with dose‐reducing technology. Additionally, we assessed applicability of 1 dose area product to effective dose conversion factor for both DARCA and conventional coronary angiography (CCA) procedures.Methods and ResultsTwenty patients were examined using DARCA and were compared with 20 age‐, sex‐, and body mass index–matched patients selected from a prior study using CCA on the same x‐ray modality. All irradiation events are simulated using PCXMC (STUK, Finland) to determine organ and effective doses. Moreover, for DARCA each frame is simulated. Staff dose is measured using active personal dosimeters (DoseAware, Philips Healthcare, The Netherlands). With DARCA, median cumulative dose area product is reduced by 57% (ie, 7.41 versus 17.19 Gy·cm2). Effective dose conversion factors of CCA and DARCA are slightly different, yet this difference is not statistically significant. The occupational dose at physician's chest, leg, and collar level are reduced by 60%, 56%, and 16%, respectively, of which the first 2 reached statistical significance. Median effective dose is reduced from 4.75 mSv in CCA to 2.22 mSv in DARCA procedures, where the latter is further reduced to 1.79 mSv when excluding ventriculography.ConclusionsDuring invasive coronary angiography, DARCA reduces radiation exposure even further toward low‐dose values on a system already equipped with advanced image processing and noise reduction algorithms. For both DARCA and CCA procedures, using 1 effective dose conversion factor of 0.30 mSv·Gy−1·cm−2 is feasible.

Simultaneous Determination of Gross Alpha/Beta Activities in Groundwater for Ingestion Effective Dose and its Associated Public Health Risk Prevention

This paper presents information on the gross alpha and gross beta activity concentrations of two hundred twenty-six groundwater samples collected by gas flow proportional counters in southern Vietnam. The gross alpha results in the water samples ranged from 0.024 to 0.748 Bq L−1 with a mean of 0.183 ± 0.034 Bq L−1, and the gross beta results in the water samples ranged from 0.027–0.632 Bq L−1 with a mean of 0.152 ± 0.015 Bq L−1. The values obtained in this work were compared with those previously published for various regions or countries. Next, untreated and treated groundwater samples were analyzed to assess their influences on the treatment process. The results showed that there were differences in the minimum detection concentrations and the mean activity values between the untreated and treated groundwater samples (The p-value of the mean comparison tests is significant with p < 0.05). In both sample groups, there was a strong positive correlation of the gross alpha versus the gross beta results (r > 0.6). This means that among the radionuclides, the major sources of beta radiation are uranium and thorium decay series radionuclides. Finally, the annual effective dose for adults (>17 years) was calculated based on the assumption that major radionuclides have the highest effective dose conversion factors. In general, the results for Pb-210, Ra-226, and Ra-228 were observed to be lower than the recommended reference values established by the World Health Organization and the International Atomic Energy Agency, except for the value of Po-210.

Estimation and comparison of the radiation effective dose during coronary computed tomography angiography examinations on single-source 64-MDCT and dual-source 128-MDCT

Goal. To estimate and compare the radiation dose associated with coronary computed tomography angiography (CCTA) examinations on two multi-detector CT scanners (MDCT), 64-MDCT and 128-MDCT, in daily practice. Methods. Scan parameters of 90 patients undergoing retrospective electrocardiographic gating spiral CCTA exam were recorded during a period on a single-source 64-MDCT and a dual-source 128-MDCT, and average scan parameters were derived that were used for dosimetry. The computed tomography dose index (CTDI) with a pencil ionisation chamber and polymethyl methacrylate body phantom with diameter of 32 cm was measured on both scanners. The dose–length product (DLP) was calculated and the DLP to effective dose conversion factor (for chest scan at 120 kV of 0.014 mSv mGy–1 cm–1) was used to estimate effective dose (ED). Results. Patients’ heart rate, scan length, pitch factor, CTDIv, DLP and ED for 128-MDCT were 64 (5) (beats min–1), 161 (10) (mm), 0.26, 47 (12) (mGy), 769 (212) (mGy cm) and 10.3 (3.1) (mSv), respectively [mean (one standard deviation)]. Patients’ heart rate, scan length, pitch factor, CTDIv, DLP and ED for 64-MDCT were 60 (7) (beats min–1), 172 (14) (mm), 0.2, 60 (6) (mGy), 1068 (98) (mGy cm) and 14.9 (1.4) (mSv), respectively. Conclusion. Our results indicated that the CTDIv, DLP and the effective dose with 128-MDCT is significantly lower than with 64-MDCT (p < 0.05). As differences between the exposure parameter mAs on two CT scanners was not significant (p > 0.05) and the kV was constant for both scanners (120 kV), the differences resulted from a shorter scan length on the 128-MDCT and use of a higher pitch factor (0.26 and 0.2 in the 128-MDCT and 64-MDCT, respectively). Comparison with other published studies confirms the findings and indicates methods for reducing patient dose.

Abstract 12818: First Experience of Three-dimensional Rotational Angiography Image Integration With Electroanatomical Mapping System to Guide Catheter Ablation of Atrial Fibrillation

Introduction: Rotational angiography of the left atrium with three-dimensional (3D) reconstruction (3D-ATG) represents a modern method enabling to create computed tomography (CT) like 3D images on a standard X-ray machine. Recently, electroanatomical mapping system can import 3D images reconstructed by 3D-ATG. Hypothesis: We assessed the hypothesis that atrial fibrillation (AF) ablation using 3D-ATG would be feasible with a significant reduction in effective dose without compromising image quality compared with 3D CT image. Methods: 3D-ATG was performed by using the Philips Allura Xper FD 10 system operated at a low-frame pulsed fluoroscopy (7.5 frames per second). Effective radiation dose was calculated from dose area product (DAP) measurements in 103 patients (mean age of 65 years, 71% men) undergoing AF ablation guided by 3D-ATG. Organ dose was measured at 37 points with a radiophotoluminescence glass dosimeter inserted in the position of an anthropomorphic Rando Phantom. Effective dose was calculated by multiplying organ dose by tissue weighting factor. The DAP to effective dose conversion factor was calculated by measurement of DAP at the same time of radiation exposure. Effective dose at CT examination was estimated from dose length product and conversion factor of 0.014. Left atrial dimensions and vertical ostial pulmonary vein (PV) diameters for each imaging method were compared. Results: The DAP to effective dose conversion factor of 3D-ATG was 2.4x10 -4 mSv/mGy•cm 2 by using the Philips Allura Xper FD 10 system in our hospital. Mean DAP for all patients was 7777±1488mGy•cm 2 for rotational angiography of the left atrium. The corresponding effective radiation doses for 3D-ATG were 1.9±0.4mSv. The effective doses for CT examinations were 13.6±4.2mSv (p&lt;0.001). The correlations of left atrial dimension were r=0.73 for sagittal plane, 0.76 for coronal, and 0.80 for vertical (p&lt;0.005). The correlation coefficient between 3D-ATG and 3D-CT for the ostial PV diameters was r=0.72 for left superior PV, 0.88 for left inferior PV, 0.60 for right superior PV, and 0.65 for right inferior PV (p&lt;0.005). Conclusions: AF ablation using 3D-ATG is possible with a significant reduction in effective dose without compromising image quality.

Radiation dosimetry of the α4β2 nicotinic receptor ligand (+)-[18F]flubatine, comparing preclinical PET/MRI and PET/CT to first-in-human PET/CT results.

BackgroundBoth enantiomers of [18F]flubatine are new radioligands for neuroimaging of α4β2 nicotinic acetylcholine receptors with positron emission tomography (PET) exhibiting promising pharmacokinetics which makes them attractive for different clinical questions. In a previous preclinical study, the main advantage of (+)-[18F]flubatine compared to (−)-[18F]flubatine was its higher binding affinity suggesting that (+)-[18F]flubatine might be able to detect also slight reductions of α4β2 nAChRs and could be more sensitive than (−)-[18F]flubatine in early stages of Alzheimer’s disease. To support the clinical translation, we investigated a fully image-based internal dosimetry approach for (+)-[18F]flubatine, comparing mouse data collected on a preclinical PET/MRI system to piglet and first-in-human data acquired on a clinical PET/CT system. Time-activity curves (TACs) were obtained from the three species, the animal data extrapolated to human scale, exponentially fitted and the organ doses (OD), and effective dose (ED) calculated with OLINDA.ResultsThe excreting organs (urinary bladder, kidneys, and liver) receive the highest organ doses in all species. Hence, a renal/hepatobiliary excretion pathway can be assumed. In addition, the ED conversion factors of 12.1 μSv/MBq (mice), 14.3 μSv/MBq (piglets), and 23.0 μSv/MBq (humans) were calculated which are well within the order of magnitude as known from other 18F-labeled radiotracers.ConclusionsAlthough both enantiomers of [18F]flubatine exhibit different binding kinetics in the brain due to the respective affinities, the effective dose revealed no enantiomer-specific differences among the investigated species. The preclinical dosimetry and biodistribution of (+)-[18F]flubatine was shown and the feasibility of a dose assessment based on image data acquired on a small animal PET/MR and a clinical PET/CT was demonstrated. Additionally, the first-in-human study confirmed the tolerability of the radiation risk of (+)-[18F]flubatine imaging which is well within the range as caused by other 18F-labeled tracers. However, as shown in previous studies, the ED in humans is underestimated by up to 50 % using preclinical imaging for internal dosimetry. This fact needs to be considered when applying for first-in-human studies based on preclinical biokinetic data scaled to human anatomy.Electronic supplementary materialThe online version of this article (doi:10.1186/s40658-016-0160-5) contains supplementary material, which is available to authorized users.

SU‐F‐I‐74: Dose Evaluation Based On Monte Carlo Simulation of Three‐Dimensional Rotational Angiography During Hepatic Transarterial Chemoembolization Procedures

Purpose:This study was aimed to investigate the dose with patient performing three‐dimensional (3D) angiography imaging during hepatic transarterial chemoembolization (TACE) procedures.Methods:Organ doses and effective doses calculations were retrospectively performed in 88 patients (61 males and 27 females with averaged age of 65.4±12.6 years old) referred for hepatic TACE on a digital flat‐panel angiography system (Bransist safire; Shimadzu) using software (PCXMC; Helsinki, Finland) based on Monte Carlo technique. Patient information (weight and height) and projection data were also used as parameters for dose calculations. Doses were evaluated of the 26 organs in 43 projections at 5° intervals from RAO 120° to LAO 95°. 3D rotational angiography images were acquired three times (before and after contrast, as well as after chemoembolization) using the same exposure techniques (100 kV, 360 mA and 5 ms pulse width) for each patient. Effective doses and dose conversion factors (CFs) were also calculated from the Monte Carlo data.Results:Upper abdominal organs, especially for the dorsal organs, showed the higher dose. Kidney received the highest dose (45.67 mGy) during the whole 3D procedure. Averaged DAP for 88 patients was 394.67±10.85 dGycm2. Averaged effective dose during the 3D procedure were 11.33 mSv. Significant inverse linear relationship was found between effective dose and patient weight (R2 =0.90). Averaged DAP‐to‐effective dose CF were 0.027 mSvdGy−1cm−2 in our study and tend to be decreased as patient weight increased (R2=0.92).Conclusion:Effective dose for the three acquisitions in the 3D rotational angiography of TACE is comparable to the effective dose for one series in the abdominal CT. By utilizing the conversion factors, the DAPs may be useful for estimating the effective dose during 3D abdominal angiographic imaging in the future.

DOSE COEFFICIENTS FOR LIVER CHEMOEMBOLISATION PROCEDURES USING MONTE CARLO CODE.

The aim of the present study is the estimation of radiation burden during liver chemoembolisation procedures. Organ dose and effective dose conversion factors, normalised to dose-area product (DAP), were estimated for chemoembolisation procedures using a Monte Carlo transport code in conjunction with an adult mathematical phantom. Exposure data from 32 patients were used to determine the exposure projections for the simulations. Equivalent organ (HT) and effective (E) doses were estimated using individual DAP values. The organs receiving the highest amount of doses during these exams were lumbar spine, liver and kidneys. The mean effective dose conversion factor was 1.4 Sv Gy-1 m-2 Dose conversion factors can be useful for patient-specific radiation burden during chemoembolisation procedures.

TH-AB-201-03: Estimating Pediatric Entrance Skin Dose From Digital Radiography Examination Using DICOM Metadata: A Quality Assurance Tool

Purpose: To develop an automated pediatric dose reporting quality assurance (QA) tool for digital radiography (DR) using DICOM metadata. Methods: Patient examination and demographical information were gathered from metadata analysis of DICOM header data. Average patient thicknesses were measured for head, chest, abdomen, knees, and hands using volumetric images from CT. Patient entrance skin air KERMA (ESAK) was calculated by first looking up examination technique factors taken from DICOM header metadata (i.e., kVp and mAs) to derive air KERMA (kair), and then scaling kair with a backscatter factor, derived from examination kVp, and for patient thickness. Finally, patient entrance skin dose (ESD) was calculated by multiplying ESAK with a mass-energy attenuation coefficient ratio. ESD to effective dose (E) conversion factors were used to estimate patient population E. ESD and E were computed for common DR examinations at our institution: dual-view chest, anteroposterier (AP) abdomen, lateral (LAT) skull, dual-view knee, and bone age (left hand only) examination. Results: ESD was calculated for 3794 patients; mean age 11 ± 8 years (range 2 months to 55 years). ESD range was: 0.19–0.42 mGy for dual-view chest, 0.28–1.2 mGy for AP abdomen, 0.18–0.65 mGy for LAT skull, 0.15–0.63 mGy for dual-view knee, and 0.10–0.12 mGy for bone age examinations. Effective dose values were calculated for dual-view chest 0.04 mSv (± 0.02 mSv), AP abdomen 0.05 mSv (± 0.15 mSv), LAT skull 0.004 mSv (± 0.002 mSv), dual-view knee 0.003 mSv (± 0.002 mSv), and bone age 0.001 mSv (± 0.0002 mSv). Conclusion: A methodology combining DICOM header metadata and basic x-ray tube characterization was demonstrated. In a regulatory era where patient dose reporting has become increasingly in demand, this methodology was used to establish an automated dose reporting program for DR to perform patient dose related QA for digital x-ray imaging.

Estimation of Radiation Dose Received in Knee Joint x-ray Examination

Abstract Background: Diagnostic X-ray examinations play an important role in the health care of the population. These examinations may involve significant irradiation of the patient and probably represent the largest manufactured source of radiation exposure for the population. Purpose: This study performed to assess the effective dose (ED) received in lumbosacral radiographic examination in order to analyze effective dose distributions among radiological departments under study. Materials and Methods: The study was performed in Khartoum teaching hospital, covering two x-ray units and a sample of 50 patients. The following parameters were recorded age, weight, height, body mass index (BMI) derived from weight (kg) and (height (m)) and exposure factors. The dose was measured for knee joint x-rays examination. For effective dose calculation, the entrance surface dose (ESD) values were estimated from the x-ray tube output parameters for knee joint AP and lateral examinations. The ED values were then calculated from the obtained ESD values using IAEA calculation methods. Effective doses were then calculated from energy imparted using ED conversion factors proposed by IAEA. Results: The results of ED values calculated showed that patient exposure were within the normal range of exposure. The mean ED values calculated were 2.49 +0.03 and 5.60 + 0.22 for knee joint AP and lateral examinations, respectively. Conclusion: Further studies are recommended with more number of patients and using more two modalities for comparison.