Estimation Of Effective Dose Research Articles

Supplementing a Web-based Exposure Estimation System with Deep Learning for Automatic Classification of CT Images to Increase the Efficiency of Effective Dose Estimation

Web-based exposure estimation systems are advantageous for estimating exposure doses for computed tomography (CT) scans. However, such systems depend on the imaging conditions of the slices, and a considerable amount of time and effort is needed to select the slices and extract their imaging conditions from the relevant CT volume data. In this study, we used a convolutional neural network (CNN) to automatically classify specific slices from available CT volume data for use by a Web-based exposure estimation system. We also proposed a method to automatically obtain the imaging conditions of these classified slices. The objective of this study was to improve the efficiency of effective dose estimation. We automatically classified specific slices from CT volume data using two different CNN architectures: VGG-16 and Xception. We organized the dataset into 5 categories corresponding to the contents of the specific slices. We also tested a 9-category version in which the slices were supplemented with their adjacent slices. We automatically obtained the imaging conditions from the DICOM tags of the specific slices that were classified from the CT volume data by the CNN and then estimated the effective exposure dose provided by the Web-based exposure estimation system. Using the 5-category dataset approach, the error in the effective exposure dose was 13% for VGG16 and 6% for Xception. When the 9-category approach was used, the error in the effective exposure dose was 0.8% for VGG16 and 0.6% for Xception. In both the architectures, less than 5 minutes was needed in the classification of the specific slices, followed by the extraction of their imaging conditions; however, VGG16 required the shortest processing time. By supplementing a Web-based exposure estimation system with a CNN and adopting our proposed method, we were able to improve the efficiency of effective dose estimation.

Calibration of a SPECT-CT gamma camera with child and adult thyroid-neck phantoms for in vivo monitoring of radioiodine in the exposed population in case of nuclear emergency

The need to quantify the uptake of 131I in the thyroid of the exposed population or workers is one of the main concerns to take into account in case of nuclear or radiological emergencies. In such scenarios, due to the high volatility and rapid intake by inhalation of 131I, it is very important a rapid identification of the exposed individuals to know their level of internal contamination in order to establish action protocols and countermeasures. In vivo measurements of 131I in the thyroid by gamma spectrometry at Whole Body Counters (WBC) is the recommended technique, but it is difficult to manage in case of a large number of individuals potentially exposed. It is known that gamma cameras located in the nuclear medicine services are available at most hospitals and could be used as an alternative method in order to provide support in the emergency response. Thus, this work describes a methodology to calibrate this kind of equipment with anthropometric phantoms to carry out direct measurement of 131I in thyroid for the quantification of internal contamination of the exposed population. A Gamma Camera (GC) of a public hospital from Madrid, H.U. La Paz, was calibrated for such purpose taking into account that a realistic geometry (10 cm distance from GC to phantom) and a rapid screening (counting time of 300 s with collimators removed) of internally contaminated individuals is necessary at early stage response. The calibration factors obtained for 131I vary with thyroid size being in the range of 0.0459 to 0.0541 cps·Bq-1. The minimum detectable activity (MDA) also varies with the thyroid size of the phantoms being in the range of 67 Bq to 79 Bq. An estimation of minimum detectable effective dose for children (E(70)) and adults (E(50)) has been carried out, taking into account such MDA values. Results show that, assuming a scenario of acute inhalation of 131I by members of the public, this methodology allows estimating doses far below 1 mSv three days after the intake. Moreover, the validation of the methodology has been carried out by participating in an international intercomparison exercise (CATHYMARA project, EC-OPERRA 2016–2017) for the in vivo measurement of 131I in thyroid to the exposed population in emergencies.

Conversion factors to estimate effective doses from kerma area product in interventional cardiology. Impact of added filtration

There is a large variation in the factors used to estimate effective doses from kerma area product (KAP) for interventional cardiology. These factors are required to estimate population doses. This paper presents the results for this conversion factor for cardiac procedures using tissue weighting factors of ICRP-103 and the impact of the added copper filtration in the X-ray beam.The data from 925 cardiac procedures and 75,347 radiation events were collected from two angiography laboratories using the DICOM Radiation Dose Structured Reports (RDSR). Effective doses were calculated with Monte Carlo software and the dosimetric, technical and geometrical information included in the RDSR.In one laboratory, with an X-ray system without Cu filtration for the cine runs, a factor of 0.21 ± 0.05 mSv/(Gy·cm2) was obtained. In other laboratory, incorporating a patient dose reduction technique, and 0.4 mm of Cu filtration for cine runs, the conversion factor was 0.29 ± 0.05 mSv/(Gy·cm2). The analysis of the radiation events for the different Cu filtrations (0.0; 0.1; 0.4 and 0.9 mm) resulted in conversion factors of: 0.16; 0.27; 0.34 and 0.40 mSv/(Gy·cm2) respectively.The estimation of effective and population doses from KAP should take into account the Cu filtration in the X-ray beam. For the X-ray system with patient dose reduction technique, using 0.4 mm Cu for cine runs, the global conversion factor increased by 38%, from 0.21 to 0.29 mSv/(Gy·cm2) in comparison to the standard X-ray system with a protocol that did not include copper filtration for cine acquisitions.

Use of radiobiology in medical jurisprudence, with particular reference to delays in diagnosis and therapeutic onset.

This paper considers aspects of radiobiology and cell and tissue kinetics applicable to legal disputations concerned with diagnostic and treatment onset delays. Various models for tumour volume changes with time are reviewed for estimating volume ranges at earlier times, using ranges of kinetic parameters. Statistical cure probability methods, using Poisson statistics with allowances for parameter heterogeneity, are also described to estimate the significance of treatment delays, as well as biological effective dose (BED) estimations of radiation effectiveness. The use of growth curves, based on parameters in the literature but with extended ranges, can identify a window of earlier times when such tumour volumes would be amenable to a cure based on the literature for curability with stage (and dimensions). Also, where tumour dimensions are not available in a post-operative setting, higher cure probabilities can be achieved if treatment had been given at earlier times. The use of radiobiological modelling can provide useful insights, with quantitative assessments of probable prior conditions and future outcomes, and thus be of assistance to a Court in deciding the most correct judgement. This study collates prior knowledge about aspects of radiobiology that can be useful in the accumulation of sufficient proof within medicolegal claims involving diagnostic and treatment days.

Dose equilibrium and CTDI quality assurance in CT and the implications for the effective dose estimation in patients

Effective dose is a single parameter meant to reflect the relative risk from exposure to ionizing radiation. It reflects the risk of detrimental biologic effects from a non- uniform, partial-body exposure in terms of a whole-body exposure1. In this study we applied the American Association of Physicists in Medicine (AAPM)2 dose equilibrium (DEq) method and the CTDI method to estimate organ dose and effective dose values and retrospectively correct the annual effective patient dose for a random sample of twenty patients. The results showed that the effective dose summed across the affected organs was underestimated by CTDI between 26 % and 31% when compared to the DEq estimate. This updated data set reflected that the effective dose to patients was up to 6 mSv greater than previously estimated through CTDI. 1. Rodrigo Canellas, Subba Digumarthy, Azadeh Tabari, Alexi Otrakji, Shaunagh McDermott, Efren J. Flores, Mannudeep Kalra. 2018. Radiation dose reduction in chest dual-energy computed tomography: effect on image quality and diagnostic information. Radiologia Brasileira 51:6, 377-384 2. AAPM. Report of AAPM Task Group 111: The Future of CT Dosimetry: Comprehensive Methodology for the Evaluation of Radiation Dose in X-Ray Computed Tomography. AAPM Report No. 111. City Park: American Association of Physicist in Medicine; 2010.

Estimation of equivalent organ and effective doses to patients undergoing coronary angiography and percutaneous coronary intervention procedures using Monte Carlo simulation

The aim of the present study was to assess the patient-specific equivalent organ dose (HT) and effective dose (ED) delivered to individual patients from cardiovascular interventional radiology (CVIR) procedures and to compare these doses to those reported in the literature. The HT and EDs to 113 patients from two CVIR procedures: coronary angiography (CA) and percutaneous coronary interventions (PCI) were acquired from two major hospitals in Tanzania. The HT and EDs were estimated using the knowledge of the patient characteristics, patient related exposure parameters, geometry of examination, measurements of air kerma area product and Monte Carlo-based PCXMC software. The median HT in the present study for the lung, heart and oesophagus for the CA, were 47.1 mSv, 33.8 mSv, and 22.9 mSv, respectively, while for the PCI were 102.6 mSv, 77.5 mSv, and 51.9 mSv, respectively. The median values of ED as recommended by ICRP 103 for the CA and PCI procedures were 11.1 mSv and 24.7 mSv, respectively. The overall variations between individual EDs across the two hospitals differed by factors of up to 63.1 and 25.1, respectively for the CA and PCI procedures. The mean values of HT and EDs in the present study were, for the most part, higher than the reported values for India, Belgium and Italy, while comparable with those reported for Greece. The proposed diagnostic reference levels (DRLs) for the CA and PCI were for KAP 91.4 Gy cm2 and 129.4 Gy cm2, for fluoroscopy time 15.5 min and 28.4 min, for number of cine frames 791.5 and 1213.5, and ED 19.8 and 36.9 mSv, respectively. The observed wide range of exposure parameters and patient doses within and across the hospitals and the observed relatively high patient doses compared to those reported in the literature, call for the need to standardize examination protocols and optimise radiation dose to patients from CVIR procedures.

Estimation of effective imaging dose and excess absolute risk of secondary cancer incidence for four-dimensional cone-beam computed tomography acquisition.

This study was conducted to estimate the organ equivalent dose and effective imaging dose for four‐dimensional cone‐beam computed tomography (4D‐CBCT) using a Monte Carlo simulation, and to evaluate the excess absolute risk (EAR) of secondary cancer incidence. The EGSnrc/BEAMnrc were used to simulate the on‐board imager (OBI) from the TrueBeam linear accelerator. Specifically, the OBI was modeled based on the percent depth dose and the off‐center ratio was measured using a three‐dimensional (3D) water phantom. For clinical cases, 15 lung and liver cancer patients were simulated using the EGSnrc/DOSXYZnrc. The mean absorbed doses to the lung, stomach, bone marrow, esophagus, liver, thyroid, bone surface, skin, adrenal glands, gallbladder, heart, intestine, kidney, pancreas and spleen, were quantified using a treatment planning system, and the equivalent doses to each organ were calculated. Subsequently, the effective dose was calculated as the weighted sum of the equivalent dose, and the EAR of the secondary cancer incidence was determined for each organ with the use of the biologic effects of ionizing radiation (BEIR) VII model. The effective doses were 3.9 ± 0.5, 15.7 ± 2.0, and 7.3 ± 0.9 mSv, for the lung, and 4.2 ± 0.6, 16.7 ± 2.4, and 7.8 ± 1.1 mSv, for the liver in the respective cases of the 3D‐CBCT (thorax, pelvis) and 4D‐CBCT modes. The lung EARs for males and females were 7.3 and 10.7 cases per million person‐years, whereas the liver EARs were 9.9 and 4.5 cases per million person‐years. The EAR increased with increasing time since radiation exposure. In clinical studies, we should use 4D‐CBCT based on consideration of the effective dose and EAR of secondary cancer incidence.

RADCOM: Radiation dose computation model- a software for radiological impact assessment

Radiological impact assessment codes are used for environmental transport and radiological impact of radionuclides releases to the environment. The RADCOM computer code performs the environmental transport of radionuclides and calculations of radiation dose to members of public due to routine releases of radionuclides from Nuclear Power Plants (NPPs) via atmospheric and aquatic routes. The code is written on Visual Basic platform and follows IAEA, Safety Reports Series No. 19 (SRS 19) and TECDOC 1616 methodologies for dose evaluation. The code comprises a large data base consisting of 114 radionuclides and respective radiological, non-radiological data and environmental parameters associated to environmental transport of radionuclides. It is designed to automate the computation of radionuclide concentrations in different environmental compartment and their impact in the food chain, as well as the estimation of effective dose to humans. The validation of software was carried out by several QC exercises following alpha and beta testing. The code was used for calculation of hypothetical scenarios given in the Annex IV of IAEA, SRS 19. Statistical significance test such as χ2 test was performed and it was found that, there is no significant difference between code output results excels generated results and reported results.

Organ and detriment-weighted dose rate coefficients for exposure to radionuclide-contaminated soil considering body morphometries that differ from reference conditions: adults and children.

The system of protection established by the International Commission on Radiological Protection (ICRP) provides a robust framework for ionizing radiation exposure justification, optimization, and dose limitation. The system is built upon fundamental concepts of a reference person, defined in ICRP Publication 89, and the radiation protection quantity effective dose, defined in ICRP Publication 103. For external exposures to radionuclide-contaminated soil, values of the organ dose rate coefficient (Gy/s per Bq/m2) and effective dose rate coefficient (Sv/s per Bq/m2) have been computed by several authors and national laboratories using ICRP-compliant reference phantoms-both stylized and voxelized. These coefficients are of great value in post-accident exposure assessments as seen in Japan following the 2011 Fukushima Daiichi nuclear power station disaster. Questions arise, however, among the general public regarding the accuracy of organ and effective dose estimates based upon reference phantom methodologies, especially for those individuals with height and/or total body mass that differ modestly or even substantially from the nearest age-matched reference person. In this pilot study, this issue is explored through use of the extended 351-member UF/NCI hybrid phantom library in which values of organ and detriment-weighted dose rate coefficients are computed for sex/height/mass-specific phantoms, and systematically compared to their values of the effective dose rate coefficient computed using corresponding reference phantoms. Results are given for monoenergetic photons, and then for some 33 different radionuclides, with all dose rate coefficient data provided in a series of electronic annexes. For environmentally relevant radionuclides such as 89Sr, 90Sr, 137Cs, and 131I, percent differences between the detriment-weighted dose rate coefficient computed using non-reference and the effective dose rate coefficient computed using reference phantoms vary only ± 5% for young children approximated by the reference 1-year-old phantom. With increased body size and age, the range of percent differences in these two quantities increases to +7% to -14% for the reference 5-year-old, to +10% to -27% for the reference 10-year-old, to +33% to -31% for the reference 15-year-old, and to +15% to -40% for male and female adults.

Evaluation of Gonadal Exposure Dose in Long Bone Plain Radiography for Radiation Protection

Introduction: Long bone examination in standing position, as one of the diagnostic methods in plain radiography, is most commonly used in the field of medical diagnosis, especially leg length discrepancy. However, with regard to this examination, reproductive organs are exposed to radiation as they are placed in the adjacent area to the long bone. Due to the sensitivity of gonads to radiation, their exposure must be kept as minimal as possible to the extent to which proper diagnosis is feasible in order to reduce tumor growth in lower extremity examination. The purpose of this study was to optimize the radiation dose in the long bone examination in standing position. Material and Methods: This experimental study was conducted to evaluate the radiation exposure dose to a phantom and estimate effective doses and organ-specific doses (i.e., testes and ovaries) among patients using PC-based Monte Carlo program. Results: A phantom examination in the posterior-anterior (PA) configuration produced a radiation dose nine and three times smaller than those in the anterior-posterior (AP) and AP with shielding configurations, respectively. In a patient study (PA configuration), the testes, ovaries and effective doses were estimated at 15, 1.2, and 2 times smaller than those in the AP configuration, respectively. Conclusion: This study demonstrated that examinations in the PA configuration produce a smaller radiation dose than those in the AP configuration.

Patient-Specific Organ and Effective Dose Estimates in Adult Oncologic CT.

OBJECTIVE. Patient-specific organ and effective dose provides essential information for CT protocol optimization. However, such information is not readily available in the scan records. The purpose of this study was to develop a method to obtain accurate examination- and patient-specific organ and effective dose estimates by use of available scan data and patient body size information for a large cohort of patients. MATERIALS AND METHODS. The data were randomly collected for 1200 patients who underwent CT in a 2-year period. Physical characteristics of the patients and CT technique were processed as inputs for the dose estimator. Organ and effective doses were estimated by use of the inputs and computational human phantoms matched to patients on the basis of sex and effective diameter. Size-based ratios were applied to correct for patient-phantom body size differences. RESULTS. Patients received a mean of 59.9 mGy to the lens of the eye per brain scan, 10.1 mGy to the thyroid per chest scan, 17.5 mGy to the liver per abdomen and pelvis scan, and 19.0 mGy to the liver per body scan. A factor of 2 difference in dose estimates was observed between patients of various habitus. CONCLUSION. Examination- and patient-specific organ and effective doses were estimated for 1200 adult oncology patients undergoing CT. The dose conversion factors calculated facilitate rapid organ and effective dose estimation in clinics. Compared with nonspecific dose estimation methods, patient dose estimations with data specific to the patient and examination can differ by a factor of 2.

Estimation of effective dose and organ cancer risk from paediatric computed tomography thorax – Abdomen - Pelvis examinations

Radiation dose exposure in computed tomography (CT) is acknowledged higher when compared to other imaging modalities. The side effects on children have always been a considerable concern. This retrospective study evaluated the dose exposure and organ cancer risk in paediatric patients who underwent CT thorax-abdomen-pelvis (CT TAP) between January 2016 and December 2018. The records of 34 boys and 39 girls (n = 73) were retrieved and divided into three age groups (0–4, 5–9 and 10–12) — the standard protocol for helical scanning setup at 100 kV and 210 mAs. Generally, the CT dose index volume, dose length product and effective dose increased in tandem with the children's age due to higher body mass index. From the youngest to the oldest age group, the liver had the highest cancer risk, especially for boys, which was most likely due to its anatomical location in the scan area. However, from age 5 and above, steep increments were observed in the risk for ovaries, whereas testicles had none. Thus, it is recommended to take precautions when subjecting children to CT TAP, especially prepubescent girls, whose ovaries exposed to almost a thousand times cancer risk per 100,000 procedure.

Dose dispersion map using the fall-out stack model of the HYSPLIT code for a pool-type 5 MW research reactor under normal operation

An investigation on the feasibility of site selection of a 5 MW research reactor, in the south of Iran (near Shiraz), is the main objective of current research. Radioactive dose dispersion map using fallout stack model, and Annual effective dose estimation of the mentioned reactor have been the main objectives. For this purpose, the HYSPLIT code is fed by leakage fission products into the environment under normal operation of the proposed reactor as well as meteorological data. Specifically, the Annual effective dose of 16 directions and in the 55 km range around the suggested site is calculated. The received doses are analyzed for three age groups including infant age, children, and adults. Results show that the maximum dose are 0.0257 (mSv/y), 0.0267 (mSv/y) and 0.027 (mSv/y) for adults, children and infants, respectively. The calculated received doses are maximized in the direction of West North West (WNW), and at 800 m distance from the selected site, which is lower the recommended dose levels for general public of ICRP-103 (1mSv/y). For the 16 directions and in the 55 km range around the suggested site, dose is within standards.

210Po as a source of natural radioactivity in cigarettes distributed in the Philippines

Abstract The natural radioactive nuclides especially 210 Po, are volatilized at the temperature (600 – 800 °C) of a burning cigarette and are taken into the human body. Therefore, analysis of natural radioactivity of 210 Po in cigarettes and the effective dose to smokers should be evaluated. The activity concentration of 210 Po in sixteen brands of Philippine cigarettes was measured by alpha spectrometry, and estimation of effective dose of 210 Po to smokers was performed. The activity concentration of 210 Po in cigarettes distributed in the Philippines ranged from 5.5 to 17.8 mBq/cigarette and the mean value of their activity concentrations was 12.0 mBq/cigarette. The mean value of annual effective doses of 210 Po to smokers obtained from these activity concentrations was 0.021 mSv/y, which was lower than the reference level (1-20 mSv/y) for existing situation in ICRP Publication 103.

Acute Rodent Tolerability, Toxicity, and Radiation Dosimetry Estimates of the S1P1-Specific Radioligand [11C]CS1P1.

In preclinical studies with rodent models of inflammatory diseases, [11C]CS1P1 has been identified as a promising imaging agent targeting sphingosine-1-phosphate receptor 1 (S1P1) in the central nervous system and other tissues. In preparation for USA Food and Drug Administration (FDA) approval of [11C]CS1P1 for human use, an acute biodistribution study in mice and an acute tolerability and toxicity evaluation in rats were conducted. Acute organ biodistribution and excretion data was obtained using male and female Swiss Webster mice intravenously (IV) injected with 4.8-10MBq of [11C]CS1P1. The organ residence times for each harvested organ were calculated using the animal biodistribution data, and were entered in the program OLINDA/EXM for C-11 to obtain human radiation dosimetry estimates. Acute tolerability and toxicity studies were conducted in male and female Sprague Dawley rats. Rats were administered an IV bolus of either the vehicle control or 0.3mg/kg CS1P1. Blood samples were collected and a gross post-mortem examination was conducted at day 2 or day 15 post-injection. The extrapolated human radiation dose estimates revealed that the highest organ dose was received by the liver with 24.05μGy/MBq in males and 32.70μGy/MBq in females. The effective dose (ED) estimates of [11C]CS1P1 were calculated at 3.5μSv/MBq in males and 5.9μSv/MBq in females. The acute tolerability and toxicity study identified 0.3mg/kg as a no observable adverse effect level (NOAEL) dose, which is a ~ 300-fold dose multiple of the human equivalent dose of the mass to be injected for positron emission tomography (PET) imaging studies in humans as a no-observable-effect limit. The toxicity study in rats suggested that injection dose of radiotracer [11C]CS1P1 with mass amount < 10μg is safe for performing a human PET study. The dosimetry data supported an injection of 0.74GBq (20mCi) dose for human studies would be acceptable.

Identification of activation products and radiation dose estimates in Havar® foils for a GE PETtrace800 medical cyclotron via high resolution gamma ray spectroscopy and MCNPX simulation

During production of F-18 in a medical cyclotron, high energy protons and secondary neutrons hit the highly reactive components of the target assembly resulting to activation products. In determining the presence of activation products and quantifying their respective activities, high resolution gamma spectroscopy using high purity germanium (HPGe) was used. From the results of the spectroscopy analysis, the doses were estimated using two methods: calculation method and MCNPX simulations. For the gamma spectroscopy analysis, the sample was prepared using aqua regia and was sent to PNRI. The analysis was done using GEM Series HPGe Coaxial Detector System. The results of the gamma spectroscopy showed the presence of 56Co, 57Co, 58Co, and 54Mn after a cooling period of eighty (80) days. For the MCNP simulations, the Havar® window foil was simulated as an isotropic disc source and a soft - tissue mimicking box detector was used and positioned at 100 cm from the center of the simulated window foil. *F8 tally was used to estimate the effective dose arising from a single activation product homogeneously distributed in the window foil and was done under the assumption that no other radiation sources were present in the simulation. Using calculation method, the effective dose estimates of 56Co, 57Co, 58Co, and 54Mn were found to be of minimal values during replacement of 18O vial at one meter. Moreover, it was found out that the highest contributors of dose during replacement of an 18O vial and maintenance of cyclotron are 56Co and 58Co. After a period of one year, the guiding activation products become 57Co and 54Mn due to their long half - lives. Furthermore, the annual dose estimates of these activation products were found to not exceed the annual dose limits for the whole body and for the extremities. As for disposal and storage, a period of four years will allow the Havar® window foil to reach the exemption levels set by PNRI.

An Investigation of Procedural Radiation Dose Level Awareness and Personal Training Experience in Communicating Ionizing Radiation Examinations Benefits and Risks to Patients in Two European Cardiac Centers.

Cardiac interventional practitioners need to be appropriately informed regarding radiation dose quantities and risks. Communicating benefit-risk information to patients requires attention as specified in Basic Safety Standards Directive 2013/59/Eurotom. This study investigated the awareness of procedural radiation dose levels and the impact of personal training experience in communicating ionizing radiation benefit-risks to patients. A questionnaire, consisting of 28 questions, was distributed directly to adult and pediatric interventional cardiology specialists at specialized cardiovascular imaging centers in Dublin, Ireland and Milan, Italy. A total of 18 interventional cardiologists (senior registrar to consultant grades with between 2 y to over 21 y experience in cardiac imaging) participated. The majority of participants (n = 17) stated that parents of pediatric and adult patients should be informed of the potential benefits and risk. All participants indicated they had radiation safety training; however, 50% had not received training in radiation examination benefit-risk communication. Despite this, 77.8% (n = 14) participants indicated a high confidence level in successfully explaining risks and/or benefits of cardiac imaging procedures. When asked to estimate effective dose (ED) values for common cardiac imaging procedures less than 50% identified appropriate dose ranges. All participants underestimated procedural dose values based on recent European data. 50% (n = 9) participants answered all questions correctly for a number of true or false radiation risk statements. Benefit-risk communication training deficits and inaccurate understanding of radiation dose levels was identified. Further research and training to support clinicians using radiation on a daily basis is required.

Estimation of Effective Dose 95 (ED95) of Intrathecal Isobaric 2-chloroprocaine (2-CP) Based on the Height (cm) of a Patient Undergoing Ambulatory Knee Arthroscopy

Estimation of Effective Dose 95 (ED95) of Intrathecal Isobaric 2-chloroprocaine (2-CP) Based on the Height (cm) of a Patient Undergoing Ambulatory Knee Arthroscopy

Patient centring and scan length: how inaccurate practice impacts on radiation dose in CT colonography (CTC).

The aim of this study was to acknowledge errors in patients positioning in CT colonography (CTC) and their effect in radiation exposure. CTC studies of a total of 199 patients coming from two different referral hospitals were retrospectively reviewed. Two parameters have been considered for the analysis: patient position in relation to gantry isocentre and scan length related to the area of interest. CTDI vol and DLP were extracted for each patient. In order to evaluate the estimated effective total dose and the dose to various organs, we used the CT-EXPO® software version 2.2. This software provides estimates of effective dose and doses to the other various organs. Average value of the patients' position is found to be below the isocentre for 48 ± 25mm and 29 ± 27mm in the prone and supine position. It was observed that the increase in CTDI and DLP values for patients in Group 1, due to the inaccurate positioning, was estimated at about 30% and 20% for prone and supine position, respectively, while in Group 2, a decrease in CTDI and DLP values was estimated at about 16% and 18% for prone and supine position, respectively, due to an average position above isocentre. A dose increase ranging from 4 up to 13% was calculated with increasing the over-scanned region below anal orifice. Radiographers and radiologists need to be aware of dose variation and noise effects on vertical positioning and over-scanning. More accurate training need to be achieved even so when examination protocol varies from general practice.

Measurement of indoor radon concentration and annual effective dose estimation for a university campus in Istanbul

Radiation is a natural part of the environment that people interact continuously, and radon is one of the most important sources because of its abundance and mobility. Due to gas form, radon can reach and accumulate in living places easily. Inhalation of radon and its progenies is an important risk factor for health hazards. Accurate measurement of radon levels is quite essential for the dose evaluation of radon exposure in buildings. In this study, radon activity measurements have been performed by using AlphaGUARD portable radon detector at several locations in Akfirat campus of Istanbul Okan University. Annual effective doses were calculated by using ICRP regulations for various exposure periods.