Low-dose CT: A safe and effective imaging modality in post-operative pelvic & acetabular fixation

INTRODUCTION

Post-operative pelvic & acetabular fixation patients are conventionally imaged using 3-view radiographs (AP, inlet and outlet). The efficacy of such radiographs is inconsistent due to technical difficulties capturing an adequate view, often necessitating repeat radiographs and therefore increasing radiation exposure. Radiographs can be difficult to interpret, limiting the assessment of fracture reduction and fixation, especially with respect to metalwork positioning around articular surfaces. Traditionally, post-operative pelvic & acetabular fixation patients undergo repeat 3-view radiographs post-operatively, at 6 weeks, followed by at 3, 6, 12, 18 and 24 months. We propose a new pathway, in which patients have one low-dose pelvic CT immediately post-operatively, followed by one radiograph (AP pelvis) at the same time points.

METHODS

A new pelvic CT protocol was created to provide high quality 3D imaging whilst delivering a 5 times lower radiation dose (compared to normal pelvic CT). Data for all pelvic radiographs and CTs between January 2021 and March 2022 was exported. Using dose area product values, effective radiation dose and attributable lifetime cancer risk were calculated.

RESULTS

There were 42 patients included in the analysis (age range 15 to 87).The average effective dose for the 3-view pelvic X-rays was 0.6mSv (range 0.2 to 2.8mSv), and 1.1mSv (range 0.5 to 2.2mSv) for the low-dose pelvic CT. Traditional 7 × 3-view post-operative radiographs: 7 × 0.6mSv = 4.2mSv (corresponding to 1 in 11,000 cancer risk) Low dose post-operative CT and 6 × 1-view radiographs: 1.1mSv + (6 × 0.6mSv / 3) = 2.3mSv (corresponding to 1 in 20,000 cancer risk) CONCLUSION: Low-dose CT scanning (in conjunction with 1-view radiographs) is an effective and safe imaging modality in the post-operative assessment of pelvic & acetabular fracture fixation, conferring a lower radiation burden, easier logistics, and higher quality images when compared to the traditional pathway of 3-view radiographs.

Assessment of the impact of Tianwan Nuclear Power Plant on the adjacent marine ecosystem

Based on the monitoring data of 137Cs and 90Sr in Tian Bay in 2005-2023, the impacts of the operation of Tianwan Nuclear Power Plant on the marine ecosystem were assessed. The 137Cs and 90Sr activity concentrations in the seawater and sediment varied within the background ranges. The radiation dose rates derived from 137Cs and 90Sr for the marine organisms ranged from 2.4 × 10-5 to 2.2 × 10-4 nGy/h, it was far below the most conservative screening dose rate (10 μGy/h). The committed effective dose for humans was 0.070-0.094 μSv, 1/1500th of the world's mean annual effective dose (0.12 mSv) from ingesting food containing uranium and thorium series nuclides. Radiation risk assessment showed no radiation risk for the long-term discharge of nuclear wastes in the future. Overall, the long-term normal operation of TNPPs has almost no radiation impact on the adjacent marine ecosystem.

Light flashes and other sensory illusions perceived in space travel and on ground, including proton and heavy ion therapies

Most of the astronauts experience visual illusions, apparent flashes of light (LF) in absence of light. The first reported observation of this phenomenon was in July 1969 by Buzz Aldrin, in the debriefing following the Apollo 11 mission. Several ground-based experiments in the 1970s tried to clarify the mechanisms behind these light flashes and to evaluate possible related risks. These works were supported by dedicated experiments in space on the following Apollo flights and in Low Earth Orbit (LEO). It was soon demonstrated that the LF could be caused by charged particles (present in the space radiation) traveling through the eye, and, possibly, some other visual cortical areas. In the 1990s the interest in these phenomena increased again and additional experiments in Low Earth Orbit and others ground-based were started. Recently patients undergoing proton and heavy ion therapy for eye or head and neck tumors have reported the perception of light flashes, opening a new channel to investigate these phenomena. In this paper the many LF studies will be reviewed, presenting an historical and scientific perspective consistent with the combined set of observations, offering a single comprehensive summary aimed to provide further insights on these phenomena. While the light flashes appear not to be a risk by themselves, they might provide information on the amount of radiation induced radicals in the astronauts' eyes. Understanding their generation mechanisms might also support radiation countermeasures development. However, even given the substantial progress outlined in this paper, many questions related to their generation are still under debate, so additional studies are suggested. Finally, it is also conceivable that further LF investigations could provide evidence about the possible interaction of single particles in space with brain function, impacting with the crew ability to optimally perform a mission.

Characterizing 226Ra and its daughters in coastal zone groundwater of a typical human-activity affected bay: occurrence, safety, and source evaluation

Due to their extremely toxic properties, 226Ra and it daughters (222Rn, 210Pb, and 210Po) in drinking groundwater require monitoring. Recent studies have reported exceptionally high levels of natural 210Po (up to 10,000 Bq/m3), 226Ra, and 222Rn isotopes in groundwater. This study aims to provide background data on 226Ra and its daughter radionuclides in the typical agricultural-industrial Dongshan Bay (DSB) before the construction of Zhangzhou Nuclear Power Plant (Zhangzhou NPP). The measurement results indicate that no abnormally high activities of 210Po and 210Pb were detected in the investigated wells. Strong positive correlations between 210Pb and 210Po, as well as between 222Rn and 210Pb activities, suggest that the origins of 210Pb and 210Po in groundwater are strongly influenced by the decay of the parent radionuclides 222Rn and 210Pb, respectively. In the DSB coastal zone groundwater, significant deficiencies of 210Po relative to 210Pb and 210Pb relative to 222Rn were observed, providing further evidence that 210Po and 210Pb are also effectively scavenged due to their geochemical properties (specifically particle affinity) within the groundwater-aquifer system. A systematic comparison among all relevant water bodies in the DSB revealed that the activity concentrations of 210Pb and 210Po in groundwater were the highest, except for rainwater. Based on the evaluation of 210Pb sources, the results imply that submarine groundwater discharge (SGD) is an important pathway for transferring radionuclides (such as 210Pb) from land to the nearshore marine environment, even though the study area has a lower 210Pb background groundwater. By considering all the 210Pb's sources in the DSB, we found low 210Pb background groundwater discharge still needs to be taken into account for small-scale bays. This is because SGD was calculated to be one of the most important 210Pb sources in the bay during observation season. Regardless of whether the system is in a normal state or a nuclear accident emergency state, greater attention should be paid to the groundwater discharge of radionuclides into the ocean.

Characterization of environmental radiological parameters on dose coefficient - Realistic dosimetry compared with epidemiological dosimetry models

Radiation exposure due to all-natural sources amounts to about 2.4 mSv per year. However, this amount might be changed to over 3 mSv y-1 according to the recently introduced ICRP radon dose coefficient factor. Previously, the radon contribution to the total dose from natural sources was about 1.2 mSv y-1. However, after the latest introduced dose conversion factor by ICRP, this value could technically be increased to around 2 mSv y-1. This paper attempts to address the following questions: (i) whether reducing radon concentration to the recommended level could address concerns about radiation exposure in underground workplaces, and (ii) the effects of the difference between the epidemiological dosimetry models and realistic dose estimation. The actual dose conversion factor (DCF) was calculated using measured annual average unattached and equilibrium factors, ranging from 16 ± 9 to 25 ± 10 mSv·WLM-1. Then, the estimated inhalation dose, both from self-calculated DCF and the value reported by ICRP-137, was compared: 5.6 ± 0.7-7.6 ± 0.9 mSv y-1 and 3.3 ± 0.4-3.6 ± 0.5 mSv y-1, respectively. It can be observed that exposure to a radon concentration lower than the recommended level does not guarantee a lower dose than the recommended value. The estimated dose was at least two times greater than the dose using pre-estimated values from epidemiological dosimetry models, specifically in this case study. Further experiments in different underground working environments, excluding caves, are needed for more precise observations. It might also be time to update the data regarding the dose contribution from natural radiation sources, as the radon contribution increased according to ICRP.

Radiation risk assessment of coastal biota from a quasi-Fukushima hypothetical accident in the Mediterranean Sea

The occurrence of the February 6, 2023, earthquake in Turkey was the idea of this research to define a Fukushima-like accident scenario in the Akkuyu nuclear reactor and investigate its radiation effects on the coastal organisms of the Mediterranean Sea. The concentration rate (CR), activity concentration in organisms, internal dose, external dose, and total dose rate were estimated using the ERICA Tool from 137Cs, 134Cs and 131I radionuclides. The minimum and maximum radiocesium CR were calculated at 0.063 Bq kg-1 fresh weight (f.w)/Bq kg-1 soil and 4.042 Bq kg-1 (f.w)/Bq kg-1 soil dry weight (d.w). Where this value for 131I ranged from 0.005 to 0.295 Bq kg-1 (f.w)/Bq kg-1 soil. For mammals-large and arthropods, we calculated the significant internal and external dose rates. All of the estimated dose rates were higher than the ICRP's derived consideration reference levels (10 μGy h-1).

Hybrid methods of radiation shielding against deep-space radiation

In the last decade, NASA and other space exploration organizations have focused on making crewed missions to different locations in our solar system a priority. To ensure the crew members' safety in a harsh radiation environment outside the protection of the geomagnetic field and atmosphere, a robust radiation protection system needs to be in place. Passive shielding methods, which use mass shielding, are insufficient as a standalone means of radiation protection for long-term deep-space missions. Active shielding methods, which use electromagnetic fields to deflect charged particles, have the potential to be a solution that can be used along with passive shielding to make deep-space travel safer and more feasible. Past active shielding studies have demonstrated that substantial technological advances are required for active shielding to be a reality. However, active shielding has shown potential for near-future implementation when used to protect against solar energetic particles, which are less penetrating than galactic cosmic rays (GCRs). This study uses a novel approach to investigate the impacts of passive and active shielding for protection against extreme solar particle events (SPEs) and free-space GCR spectra under solar minimum and solar maximum conditions. Hybrid shielding configuration performance is assessed in terms of effective dose and radiobiological effectiveness (RBE)-weighted dose reduction. A novel electrostatic shielding configuration consisting of multiple charged planes and charged rods was chosen as the base active shielding configuration. After a rigorous optimization process, two hybrid shielding configurations were chosen based on their ability to reduce RBE-weighted dose and effective dose. For protection against the extreme SPE, a hybrid active-passive shielding configuration was chosen, where active shielding was placed outside of passive shielding. In the case of GCRs, to gain additional reduction compared to passive shielding, the passive shielding configuration was placed before the active shielding to intentionally fragment HZE ions to improve shielding performance.

Impact of long-term operation of nuclear power plants on the marine ecosystem of Daya Bay

Based on the monitoring data of Daya Bay in 2011-2017, the impact of long-term operation of nuclear power plants (NPPs) on the marine ecosystem was accessed. ¹³⁷Cs and ⁹⁰Sr in seawater and sediment of Daya Bay decreased with time. The environmental half-lives of ¹³⁷Cs and ⁹⁰Sr in seawater, ¹³⁷Cs in sediment were 7.1 a, 11.7 a and 13.9 a, respectively. The total dose rates of the marine organisms ranged from 230.5 to 853.9 nGy/h, lower than the ERICA screening benchmark (10 μGy/h). ²¹⁰Po, ²²⁶Ra and ²³²Th were the main dose contributors. ¹³⁷Cs and ⁹⁰Sr contributed to ~0.01 %-~0.06 % of the total radiation. ¹³⁷Cs contributed to <0.6 ‰ of the committed effective dose for humans. There were almost no radiation effects on the marine ecosystem of Daya Bay from NPPs before 2017. In the future, there will be no radiation risk for the long-term discharge of low-level radioactive waste to Daya Bay.

Algorithm for Reducing Overall Biological Detriment Caused by PET/CT: an Age-Based Study

Purpose

This study is to use a simple algorithm based on patient's age to reduce the overall biological detriment associated with PET/CT.

Materials and Methods

A total of 421 consecutive patients (mean age 64 ± 14 years) undergoing PET for various clinical indications were enrolled. For each scan, effective dose (ED in mSv) and additional cancer risk (ACR) were computed both in a reference condition (REF) and after applying an original algorithm (ALGO). The ALGO modified the mean dose of FDG and the PET scan time parameters; indeed, a lower dose and a longer scan time were reported in the younger, while a higher dose and a shorter scan time in the older patients. Moreover, patients were classified by age bracket (18-29, 30-60, and 61-90 years).

Results

The ED was 4.57 ± 0.92 mSv in the REF condition. The ACR were 0.020 ± 0.016 and 0.0187 ± 0.013, respectively, in REF and ALGO. The ACR for the REF and ALGO conditions were significantly reduced in males and females, although it was more evident in the latter gender (all p < 0.0001). Finally, the ACR significantly reduced from the REF condition to ALGO in all three age brackets (all p < 0.0001).

Conclusion

Implementation of ALGO protocols in PET can reduce the overall ACR, mainly in young and female patients.

Assessment of male patients' average glandular dose during mammography procedure

Breast cancer is a common malignancy for females (25% of female cancers) and also has low incidence in males. It was estimated that 1% of all breast malignancies occur in males with mortality rate about 20%, with annual increase in incidence. Risk factors include age, family history, exposure to ionizing radiation and high estrogen and low of androgens hormones level. Diagnosis and screening are challenging due to limiting effectiveness of breast cancer screening. Therefore, patients may expose to ionizing radiation that may contribute in breast cancer incidence in males. In literature, limited studies were published regarding radiation exposure for males during mammography. The objective of this research is to quantify patient doses during male mammogram and to estimate the projected radiogenic risk during the procedure. In total, 42 male patients were undergone mammogram for breast cancer diagnosis during two consecutive years. The mean and range of patient age (years) is 45 (23-80). The mean and standard deviation (SD) of the peak tube potential and tube current time product are 28.64 ± 2. and 149 ± 35.1, respectively. The mean, and range of patients' entrance surface air kerma (ESAK, mGy) per single breast procedure was 5.3 (0.47-27.5). Male patient's received comparable radiation dose per mammogram compared to female procedures. With increasing incidence of male breast cancer, proper guidelines are necessary for the mammographic procedure are necessary to reduce unnecessary radiation doses and radiogenic risk.

Patient's effective dose and performance assessment of computed radiography systems

Computed tomography is widely used for planar imaging. Previous studies showed that CR systems involve higher patient radiation doses compared to digital systems. Therefore, assessing the patient's dose and CR system performance is necessary to ensure that patients received minimal dose with the highest possible image quality. The study was performed at three medical diagnostic centers in Sudan: Medical Corps Hospital (MCH), Advance Diagnostic Center (ADC), and Advance Medical Center (AMC). The following tools were used in this study: Tape measure, Adhesive tape, 1.5 mm copper filtration (>10 × 10 cm), TO 20 threshold contrast test object, Resolution test object (e.g., Huttner 18), MI geometry test object or lead ruler, Contact mish, Piranha (semiconductor detector), Small lead or copper block (∼5 × 5 cm), and Steel ruler, to do a different type of tests (Dark Noise, Erasure cycle efficiency, Sensitivity Index calibration, Sensitivity Index consistency, Uniformity, Scaling errors, Blurring, Limiting spatial Resolution, Threshold, and Laser beam Function. Entrance surface air kerma (ESAK (mGy) was calculated from patient exposure parameters using DosCal software for three imaging modalities. A total of 199 patients were examined (112 chest X rays, 77 lumbar spine). The mean and standard deviation (sd) for patients ESAK (mGy) were 2.56 ± 0.1 mGy and 1.6 mGy for the Anteroposterior (AP) and lateral projections for the lumbar spine, respectively. The mean and sd for the patient's chest doses were 0.1 ± 0.01 for the chest X-ray procedures. The three medical diagnostic centers' CR system performance was evaluated and found that all of the three centers have good CR system functions. All the centers satisfy all the criteria of acceptable visual tests. CR's image quality and sensitivity were evaluated, and the CR image is good because it has good contrast and resolution. All the CR system available in the medical centers and upgraded from old X-ray systems to new systems, has been found to work well. The patient's doses were comparable for the chest X-ray procedures, while patients' doses from the lumbar spine showed variation up to 2 folds due to the variation in patients' weight and X-ray machine setting. Patients dose optimization is recommended to ensure the patients received a minimal dose while obtaining the diagnostic findings.

Assessment of patients radiation doses associated with computed tomography coronary angiography

Computed tomography coronary angiography (CTCA) has generated tremendous interest over the past 20 years by using multidetector computed tomography (MDCT) because of its high diagnostic accuracy and efficacy in assessing patients with coronary artery disease. This technique is related to high radiation doses, which has raised serious concerns in the literature. Effective dose (E, mSv) may be a single parameter meant to reflect the relative risk from radiation exposure. Therefore, it is necessary to calculate this quantity to point to relative radiation risk. The objectives of this study are to evaluate patients' exposure during diagnostic CCTA procedures and to estimate the risks. Seven hundred ninety patients were estimated during three successive years. The patient's exposure was estimated based on a CT device's delivered radiation dose (Siemens Somatom Sensation 64 (64-MDCT)). The participating physicians obtained the parameters relevant to the radiation dose from the scan protocol generated by the CT system after each CCTA study. The parameters included the volume CT dose index (CTDIvol, mGy) and dose length product (DLP, mGy × cm). The mean and range of CTDIvol (mGy) and DLP (mGy × cm) for three respective year was (2018):10.8 (1.14-77.7) and 2369.8 ± 1231.4 (290.4-6188.9), (2019): 13.82 (1.13-348.5), and 2180.5 (501.8-9534.5) and (2020) 10.9 (0.7-52.9) and 1877.3 (149.4-5011.1), respectively. Patients' effective doses were higher compared to previous studies. Therefore, the CT acquisition parameter optimization is vital to reduce the dose to its minimal value.

[Information, informed consent, and communication with patients]

The transposition of EU Directive 2013/59/Euratom into German law requires that patients be informed about the radiation risk of radiological procedures. Such information is not the same as a medical informed consent about immediate risks associated with the procedure, such as deterministic radiation damage, risks of contrast media, or complications. The sole use of X‑rays in diagnostic procedures therefore requires no informed consent in most cases.

Typical effective dose values from diagnostic and interventional radiology

Effective dose (E) in medical procedures is of practical value for comparing doses from different types of procedures which is not possible with the different measurable dose quantities. In this survey we estimated and compared the values of E in 12 medical imaging procedures. The mean E for conventional X-ray in mSv were ranged between 0.01 for skull lateral to 0.5 for abdominal while the mean E for cardiac interventional radiology in mSv was up to 16 for percutaneous transluminal coronary angioplasty (PTCA). For dental radiology the mean E in μSv was 1.2 for intraoral and 10 for panoramic. In mammography the mean E was 0.5 mSv. Compared with the literature, chest postero-anterior (PA), lumbar spine AP, PTCA and mammography procedures had shown larger E values. The obtained results can help in justification of techniques.

On a risk of inhalation exposure during visits in Chernobyl exclusion zone

In recent years Chernobyl exclusion zone has become a very popular tourist destination. Many people visiting power plant, Pripyat city or surrounding villages use different types of personal dosimeters to control external exposure, however very small group of tourist have opportunity to control internal contamination of respiratory tract using dedicated, high sensitive whole body counters. In this study 11 anti-dust masks collected from CEZ visitors and filters from one military MP-5 mask were analyzed using alpha, beta and gamma spectrometry to determine doses from actinides and fission products which can be inhaled without proper protective equipment. Results showed, that average effective dose from inhalation of contaminated aerosol in case of single-day trip (avoided due to use of mask) was 1.3 μSv per person, which is much smaller than potential effective dose after exploration of highly contaminated areas like Jupiter complex, where combined dose from all measured nuclides collected on MP-5 mask filter was 1.4 mSv.

Radiation exposure and risk assessment to earthworms in areas contaminated with naturally occurring radionuclides

The assessment of radiation exposure on biota is one of the main parts of environment protection system. Earthworms have been recognized as an important organism group in the terrestrial ecosystems. According to many researchers the potential risks of naturally occurring radionuclides for soil invertebrates were not significant because the exposure doses to the invertebrate populations were low. Our study aimed to assess the radiation exposure and the radiological risks from naturally occurring radionuclides for earthworm populations at four sites. This research was based on three dosimetric approaches simultaneously: ERICA and RESRAD-BIOTA-the commonly used ones, and also on the original method proposed by Thomas and Liber (Environment International, 27, 341-353, 2001) for aquatic organisms. To calculate radiation dose rates to soil invertebrates inhabiting background and contaminated areas, the specific activities of radionuclides in soil, and, depending on the model, the default, or determined in this study, input mass-geometric parameters had been applied. The weighted absorbed dose rates calculated by different models and site-specific data were 0.3-1.4 μGy/h for the background and from 3.4 to 170 μGy/h for the contaminated sites. Analysis of radiation risks for earthworms indicated that ²²⁶Ra was the key contributor to the external dose rate; ²²⁶Ra and ²¹⁰Po played a dominant role in formation of internal dose rate for radioecological situations in our study. More conservative radiation risk assessments were derived from RESRAD-BIOTA tool. Dose assessments obtained using various models had shown that there are real environmental situations in which the radiological risks to reference organisms are significantly higher than the lowest benchmark protection level proposed for ecosystems.

In-vivo dose determination in a human after radon exposure: proof of principle

Radon-222 is pervasive in our environment and the second leading cause of lung cancer induction after smoking while it is simultaneously used to mediate anti-inflammatory effects. During exposure, radon gas distributes inhomogeneously in the body, making a spatially resolved dose quantification necessary to link physical exposure conditions with accompanying risks and beneficial effects. Current dose predictions rely on biokinetic models based on scarce input data from animal experiments and indirect exhalation measurements of a limited number of humans, which shows the need for further experimental verification. We present direct measurements of radon decay in the abdomen and thorax after inhalation as proof of principle in one patient. At both sites, most of the incorporated radon is removed within ~ 3 h, whereas a smaller fraction is retained longer and accounts for most of the deposited energy. The obtained absorbed dose values were [Formula: see text] µGy (abdomen, radon gas) and [Formula: see text] µGy (thorax, radon and progeny) for a one-hour reference exposure at a radon activity concentration of 55 kBq m^-3. The accumulation of long-retained radon in the abdomen leads to higher dose values at that site than in the thorax. Contrasting prior work, our measurements are performed directly at specific body sites, i.e. thorax and abdomen, which allows for direct spatial distinction of radon kinetics in the body. They show more incorporated and retained radon than current approaches predict, suggesting higher doses. Although obtained only from one person, our data may thus represent a challenge for the barely experimentally benchmarked biokinetic dose assessment model.

Low dose radiation mechanisms: The certainty of uncertainty

This paper reviews the current understanding of low dose radiobiology, and how it has evolved from classical target theory. It highlights the uncertainty around low dose effects, which is due in part to the complexity of "context" surrounding the ultimate expression of biological effects following low dose exposure. The paper makes special reference to low dose non-targeted effects which, are currently ignored in radiation protection and population level risk assessment, because it is unclear what they mean for risk. The view of the authors is that this "lack of clarity" about what the effects mean is precisely the point. It indicates the uncertainty of outcomes after a given exposure. The uncertainty stems from multiple outcome options resulting from the intrinsic uncertainty of the stochastic interaction of low dose radiation with matter. This uncertainty should be embraced rather than eschewed. The impacts of the uncertainties identified in this paper is explored and an approach to quantifying mutation probability in relation to dose is presented.

Modelling the radioactive contamination of commercial fish species in the Barents Sea following a hypothetical short-term release to the Stepovogo Bay of Novaya Zemlya

A dynamic modelling of radionuclides accumulation in commercial species in the Barents Sea is performed for hypothetical SCR accident with the dumped submarine K-27 at the Stepovogo Bay. Box radioecological model is employed for calculating the radionuclides dynamics in water, bottom sediments and marine biota. The model takes into account the seasonal fish migrations in the Barents Sea. The model allows predicting the dynamic effects of the radionuclide transfer in fish in case of an accidental water contamination. Maximum ¹³⁷Cs activity concentrations in bottom sediments from the eastern part of the Barents Sea could be reached as late as 5-6 years after the accidental release. Based on the results of model calculations, assessment was made of doses to humans from consumption of seafood contaminated after a hypothetical SCR accident with K-27 at the Stepovogo Bay. The peak activity concentration of the released ¹³⁷Cs in fish from the Stepovogo Bay is calculated to be 109 Bq∙kg^-1, ⁹⁰Sr - 12 Bq∙kg^-1; both estimates are below the permissible activity concentrations of these radionuclides in commercial fish. Predicted maximum annual dose from consumption of fish from the Stepovogo Bay is 47 ± 18 μSv∙year^-1, the Barents Sea fish - less than 3∙10^-6 μSv∙year^-1.¹³⁷Cs is the major dose contributor; it provides more than 99% to the annual dose Radiation risks from consumption of the Barents Sea commercial fish are evaluated to be negligible in case of a hypothetical SCR accident with the submerged submarine K-27 in Stepovogo Bay of Novaya Zemlya.

Elimination of biological and physical artifacts in abdomen and brain computed tomography procedures using filtering techniques

•

Filters reduce the noise at the expense of visual image quality.

•

Digital interpretation of images prevents misinterpretation of the images due to blurring of the images.

•

Dose reduction without compromising the diagnostic.

Introduction

Medical images are usually affected by biological and physical artifacts or noise, which reduces image quality and hence poses difficulties in visual analysis, interpretation and thus requires higher doses and increased radiographs repetition rate.

Objectives

This study aims at assessing image quality during CT abdomen and brain examinations using filtering techniques as well as estimating the radiogenic risk associated with CT abdomen and brain examinations.

Materials and Methods

The data were collected from the Radiology Department at Royal Care International (RCI) Hospital, Khartoum, Sudan. The study included 100 abdominal CT images and 100 brain CT images selected from adult patients. Filters applied are namely: Mean filter, Gaussian filter, Median filter and Minimum filter. In this study, image quality after denoising is measured based on the Mean Squared Error (MSE), Peak Signal-to-Noise Ratio (PSNR), and the Structural Similarity Index Metric (SSIM).

Results

The results show that the images quality parameters become higher after applications of filters. Median filter showed improved image quality as interpreted by the measured parameters: PSNR and SSIM, and it is thus considered as a better filter for removing the noise from all other applied filters.

Discussion

The noise removed by the different filters applied to the CT images resulted in enhancing high quality images thereby effectively revealing the important details of the images without increasing the patients’ risks from higher doses.

Conclusions

Filtering and image reconstruction techniques not only reduce the dose and thus the radiation risks, but also enhances high quality imaging which allows better diagnosis.

Interpreting Quality Improvement When Introducing New Technology: A Collaborative Experience in ASD Device Closures

The objective of this study was to evaluate the impact of the regular introduction of new technologies into interventional cardiac catheterization procedures, in this case new atrial septal defect (ASD) closure devices, while conducting a multi-center collaborative initiative to reduce radiation usage during all procedures. Data were collected prospectively by 8 C3PO institutions between January 1, 2014 and December 31, 2017 for ASD device closure procedures in the cardiac catheterization lab during a quality improvement (QI) initiative aimed at reducing patient radiation exposure. Radiation exposure was measured in dose area product per body weight (µGy*m²/kg). Use of proposed practice change strategies at the beginning and end of the QI intervention period was assessed. Radiation exposure was summarized by institution and by initial type of device used for closure. This study included 602 ASD device closures. Without changes in patient characteristics, total fluoroscopy duration, or number of digital acquisitions, median radiation exposure decreased from 37 DAP/kg to 14 DAP/kg from 2014 to 2017. While all individual centers decreased overall median DAP/kg, the use of novel devices for ASD closure correlated with a temporary period of worsening institutional radiation exposure and increased fluoroscopy time. The introduction of new ASD closure devices resulted in increased radiation exposure during a QI project designed to reduce radiation exposure. Therefore, outcome assessment must be contextualized in QI projects, hospital evaluation, and public reporting, to acknowledge the expected variation during innovation and introduction of novel therapies.

A review of screening mammography: The benefits and radiation risks put into perspective

INTRODUCTION/BACKGROUND

In medical imaging a benefit to risk analysis is required when justifying or implementing diagnostic procedures. Screening mammography is no exception and in particular concerns around the use of radiation to help diagnose cancer must be addressed.

METHODS

The Medline database and various established reports on breast screening and radiological protection were utilised to explore this review.

RESULTS/DISCUSSION

The benefit of screening is well argued; the ability to detect and treat breast cancer has led to a 91% 5-year survival rate and 497 deaths prevented from breast cancer amongst 100,000 screened women. Subsequently, screening guidelines by various countries recommend annual, biennial or triennial screening from ages somewhere between 40-74 years. Whilst the literature presents different perspectives on screening younger and older women, the current evidence of benefit for screening women <40 and ≥75 years is currently not strong. The radiation dose and associated risk delivered to each woman for a single examination is dependent upon age, breast density and breast thickness, however the average mean glandular dose is around 2.5-3 mGy, and this would result in 65 induced cancers and 8 deaths per 100,000 women over a screening lifetime from 40-74 years. This results in a ratio of lives saved to deaths from induced cancer of 62:1.

CONCLUSION

Therefore, compared to the potential mortality reduction achievable with screening mammography, the risk is small.

Transthoracic echo-guided pacemaker implantation reduces fluoroscopic use in dogs

Echocardiographic guidance provides an alternative method when fluoroscopy is unavailable, equipment or power failure of fluoroscopic equipment during a procedure occurs or to decrease radiation risk. Recently, transthoracic (TTE) and transesophageal echocardiography were reported as an alternative method to guide interventional procedures in dogs. Therefore, we hypothesized that TTE could be used as an alternative method to visualize endocardial leads during pacemaker implantation in dogs, largely avoiding the use of fluoroscopy. A prospective consecutive case series of pacemaker implantation was performed using TTE guidance. The endocardial lead was imaged by TTE during its intracardiac advancement until the lead tip was positioned at the right ventricular apex. Echocardiographic right parasternal views, optimized to visualize the pacing lead, were used, starting with a short axis image of the right atrium and ending with a long axis view of the right ventricle (RV) optimized to image the RV apex. Proper lead placement was confirmed by both capture threshold, impedance and fluoroscopy. Twenty-one pacemaker implantation procedures by TTE monitoring were successfully performed. The TTE guidance provided images of a quality sufficient to clearly monitor implantation in real-time and allowed for immediate corrections to pacing lead malpositioning or excessive looping. Fluoroscopy was used to confirm the correct placement of the lead that was guided echocardiographically in the initial three procedures, after which a single radiographic image (no cine-mode) was used to identify lead placement and redundancy in the remaining eighteen cases. Static imaging (radiography using the fluoroscope) was used to assess the proper lead redundancy in all procedures because this cannot be evaluated echocardiographically. Pacemaker leads were successfully implanted in the RV of dogs using TTE monitoring. A larger cases series is needed for validation of safety and effectiveness of TTE during this interventional procedure in dogs.

Occupational and patients effective radiation doses in dental imaging

Ionizing radiation exposure from medical applications is increasing annually worldwide. It was estimated that 325 million dental procedures were performed in the United States. Radiation exposure from dental radiography consists of intraoral, panoramic, and 3D imaging cone-beam computed tomography (CBCT) imaging. Recent studies reported an association between dental imaging procedures and increased cancer probability of brain and thyroid. Previous studies showed that some dental imaging practices exposed patients and staff to unnecessary radiation doses due to incorrect image acquisition and insufficient radiation protection measures. This study aims to (i) measure the occupational and patients doses during dental procedures and (ii) assess the current imaging techniques and radiation protection practices. Two hundred fourteen patients were evaluated for periapical, bitewing, cephalometric, occlusal, and panoramic procedures. Organ equivalent doses were quantified for the breast, eye lens, and thyroid gland during CBCT procedure. Occupational and ambient dose assessment were assessed using calibrated thermoluminescent dosimeters (TLD-100(LiF: Mg. Ti). Ambient doses were measure at different locations at the department using TLDs. Patients' radiation doses were quantified using kerma area product (PKA (mGy.cm) and the entrance surface air kerma (ESAK (mGy). Fixed tube voltage (65 kVp) and tube current-time product (7 mAs) were used. The overall mean, sd, and range of patients dose values during intraoral (mGy), panoramic and CBCT examinations were 4.6 ± 0.7 (1.4-7.1), 135 ± 45 (75.2-168.5), and 215 ± 165 (186-2115), respectively. The mean and range of the annual occupational doses (mSv) were 1.4 (0.6-3.7), which below the annual dose limits for radiation workers (20 mSv/y). The study showed that inadequate radiation protection for patients existed in terms of the use of the thyroid shield, the technologist's presence inside the room during radiation exposure. Patients' radiation doses were comparable with the international diagnostic reference level (DRL). Staff education and training in radiation protection aspects are highly recommended.

A new type of ground-based simulator of radiation field inside a spacecraft in deep space

The problem of full-scale ground-based modeling of cosmic radiation on heavy-ion accelerators for space radiobiology is very urgent. A new type of space radiation simulator at the ⁵⁶Fe ion beam with energy 1 GeV/n is proposed. The simulator uses rotating converters consisting of segmented targets with varying thicknesses. When a flat uniform field of primary ⁵⁶Fe ions is used, this design ensures the uniformity of the fields of all secondary particles behind the targets. The proposed setup with four replaceable converters makes it possible to simulate not only the distribution of linear energy transfers of cosmic radiation but also reproduce continuous energy spectra of all charged fragments of the projectile ion from protons to Co. The results of simulation of the internal radiation field inside the habitable module of a spacecraft with a shell of 15 g/cm² Al, generated by particles of galactic cosmic rays in the solar activity range from 0 to 190 Wolf numbers, are presented.

Estimating long-term health risks after breast cancer radiotherapy: merging evidence from low and high doses

In breast cancer radiotherapy, substantial radiation exposure of organs other than the treated breast cannot be avoided, potentially inducing second primary cancer or heart disease. While distant organs and large parts of nearby ones receive doses in the mGy-Gy range, small parts of the heart, lung and bone marrow often receive doses as high as 50 Gy. Contemporary treatment planning allows for considerable flexibility in the distribution of this exposure. To optimise treatment with regards to long-term health risks, evidence-based risk estimates are required for the entire broad range of exposures. Here, we thus propose an approach that combines data from medical and epidemiological studies with different exposure conditions. Approximating cancer induction as a local process, we estimate organ cancer risks by integrating organ-specific dose-response relationships over the organ dose distributions. For highly exposed organ parts, specific high-dose risk models based on studies with medical exposure are applied. For organs or their parts receiving relatively low doses, established dose-response models based on radiation-epidemiological data are used. Joining the models in the intermediate dose range leads to a combined, in general non-linear, dose response supported by data over the whole relevant dose range. For heart diseases, a linear model consistent with high- and low-dose studies is presented. The resulting estimates of long-term health risks are largely compatible with rate ratios observed in randomised breast cancer radiotherapy trials. The risk models have been implemented in a software tool PASSOS that estimates long-term risks for individual breast cancer patients.

Assessment of patients' cumulative doses in one year and collective dose to population through CT examinations

PURPOSE

To estimate percentage of patients undergoing multiple CT exams leading to cumulative effective dose (CED) of more than 25, 50, 75 and 100 mSv in one year and assess per capita and the collective effective dose.

METHODS

Data from a regional hospital network was collected retrospectively using radiation dose monitoring system at 6 facilities with 8 CT scanners. The data was analyzed to find number of patients in different dose groups, their age, gender, number of CT exams and exams needed to reach 100 mSv based on age groups.

RESULTS

In one year 43,010 patients underwent 75,252 CT examinations. The number of exams per 1000 population was 153. Further 27% of the patients were younger than 55- years and 15.9% of them were younger than 45-year-old. A total of 0.67% of patients received a CED > 100 mSv; 3.5% had CED > 50 mSv, 11.9% with CED > 25 mSv and the maximum CED was 529 mSv. The minimum time to reach 100 mSv was a single CT exam. Seven patients received > 100 mSv in a single CT exam. 0.36% of patients had 10 or more CT exams in one year and 3.8% had 5 or more CT exams. The mean CED was 12.3 mSv, the average individual effective dose was 1.1 mSv and the collective effective dose was 521.3 person-Sv.

CONCLUSIONS

The alarming high CED received by large number of patients and with high collective dose to population requires urgent actions by all stake holders in the best interest of patient radiation safety.

Radiation exposure to infants undergoing voiding cystourethrography: The importance of the digital imaging technology

PURPOSE

To determine the radiation burden to infants undergoing voiding cystourethrography (VCUG) in a single institution and investigate the effect of shifting from analogue to digital imaging that allowed the use of a radiography-free examination protocol.

METHODS

Anthropometric and exposure data were prospectively collected for 35 consecutive infants undergoing VCUG on a digital system with a standardized examination protocol not including radiographs. Thermoluminescent dosimeters were used to determine entrance-skin dose. Monte Carlo simulations and patient-specific anthropomorphic phantoms were employed to determine organ/tissue doses and effective dose (ED). The associated theoretical risk of radiation-induced cancer was determined and compared to the nominal risk of cancer induction. The radiation burden from VCUG on a modern digital system with a contemporary examination protocol was compared to corresponding data reported previously for an analogue system in the same institution.

RESULTS

The median ED from VCUG was found 47 μSv. The associated total life attributable risk of radiation-induced cancer was found 10x10^-6 and 13x10^-6 for boys and girls, respectively. VCUG was found to increase the nominal risk of cancer by a factor of 1.000025 in boys and 1.000034 in girls. Shifting from analogue to digital imaging system resulted in 89% reduction of the radiation burden from VCUG.

CONCLUSION

The theoretical radiation risks for infants undergoing VCUG using a modern digital imaging system and a radiography-free protocol were found to be minor. The transition from analogue to digital equipment resulted in considerable reduction of the radiation burden from VCUG.

Let Chromosomes Speak: The Cytogenetics Project at the Atomic Bomb Casualty Commission (ABCC)

Hibakusha (atomic bomb survivors) are "witnesses" of the atomic bombings, not just in a standard sense but also in the instrumental sense. For medical and scientific experts, hibakusha are biological resources of unparalleled scientific value. Over the past seventy years, the hibakusha bodies have narrated what it means to be exposed to radiation. In this paper, I explore studies at the Atomic Bomb Casualty Commission (ABCC) that examined hibakusha bodies as sites where risk could be read. I focus on a period from the mid-1950s to 1975, during which new methods, practices, and technologies allowed ABCC scientists to investigate chromosomes as a way to study radiation exposure and human risk. By focusing on chromosomal aberrations, ABCC scientists connected their work directly to the emerging infrastructure for radiobiology at the time. ABCC administrators actively sought out such prestige, especially given their relationship with the Atomic Energy Commission (AEC). The shift in approach would also alleviate some public relations problems with which the institution was struggling. Launching a cytogenetics program required some older practices that had assumed American privilege and dominance to be abandoned. Eventually, the decision to let chromosomes speak of radiation exposure brought about fundamental changes in ABCC, which came to symbolize the model for future studies at the organization, especially as ABCC was transitioning to a US-Japan binational organization. More broadly, this case highlights the intricate scientific negotiation of radiation risk where uncertainties necessarily prevail.

Computed tomography colonography and radiation risk: How low can we go?

Computed tomography colonography (CTC) has become a key examination in detecting colonic polyps and colorectal carcinoma (CRC). It is particularly useful after incomplete optical colonoscopy (OC) for patients with sedation risks and patients anxious about the risks or potential discomfort associated with OC. CTC's main advantages compared with OC are its non-invasive nature, better patient compliance, and the ability to assess the extracolonic disease. Despite these advantages, ionizing radiation remains the most significant burden of CTC. This opinion review comprehensively addresses the radiation risk of CTC, incorporating imaging technology refinements such as automatic tube current modulation, filtered back projections, lowering the tube voltage, and iterative reconstructions as tools for optimizing low and ultra-low dose protocols of CTC. Future perspectives arise from integrating artificial intelligence in computed tomography machines for the screening of CRC.

Risk perception of radiation emergency medical staff on low-dose radiation exposure: Knowledge is a critical factor

Radiation emergency medical (REM) staff respond to many types of disasters such as radiological and nuclear accidents as well as environmental radioactivity exposure. The objective of this study was to evaluate the risk perception of REM staff on radiation exposure in various situations and to analyze the factors that affect their risk perception. A questionnaire was given to 284 REM staff affiliated with various organizations, including nuclear power generation, nuclear fuel manufacturing, large-scale irradiation, and radiation-waste disposal facilities, as well as research and development institutions. To determine the substantially influential factors for risk perception, we analyzed the questionnaire responses using ordinal logistic regression, Kruskal-Wallis, and Spearman correlation analyses. It was generally perceived by REM staff that low-dose radiation exposure in daily life and work environments does not pose any health risks. A higher level of radiation knowledge was tightly associated with a lower risk perception of REM staff on extremely low-dose (several mSv) radiation exposure, thus exhibiting an inverse correlation. In contrast to radiation researchers, the work experience of REM staff was not a contributing factor to their risk perception. In our study, REM staff with a high level of radiation knowledge did not have any health concerns in their work environments. Efforts to enhance the radiation knowledge of REM staff through proper education and training would result in analytical risk evaluation, which may also improve their willingness to help meet surge capacity needs in large-scale radiological events.

Multivariate statistical approach on distribution of natural and anthropogenic radionuclides and associated radiation indices along the north-western coastline of Aegean Sea, Greece

A comprehensive radiological survey using multivariate statistical analysis was carried out to evaluate the distribution of ⁴⁰K, ²³²Th, ²²⁶Ra, ²³⁵U, and ¹³⁷Cs, and associated radiation indices in beach sand samples of the coastal area of the Aegean Sea. The activity concentration of selected radionuclides was measured and no clue of recent migration of radiocaesium by not only precipitation but also through an indirect way, such as ocean runoff, was found. As part of radiological risk assessment, external radiation hazard index, radium equivalent activity, effective dose, and absorbed dose rate were estimated. Pearson correlation, cluster, and PCA analysis were used by processing observed radiological parameters to determine the correlation between the radiological parameters and locations. Pearson correlation shows a strong association between all parameters and activity of ²²⁶Ra and ²³²Th. A spatial distribution map was provided to a distinct visual representation of the distribution of radionuclide contents in the study area.

Mortality among individuals exposed to atomic bomb radiation in utero: 1950-2012

We examined the mortality risks among 2463 individuals who were exposed in utero to atomic bomb radiation in Hiroshima or Nagasaki in August 1945 and were followed from October 1950 through 2012. Individual estimates of mother's weighted absorbed uterine dose (DS02R1) were used. Poisson regression method was used to estimate the radiation-associated excess relative risk per Gy (ERR/Gy) and 95% confidence intervals (CI) for cause-specific mortality. Head size, birth weight, and parents' survival status were evaluated as potential mediators of radiation effect. There were 339 deaths (216 males and 123 females) including deaths from solid cancer (n = 137), lymphohematopoietic cancer (n = 8), noncancer disease (n = 134), external cause (n = 56), and unknown cause (n = 4). Among males, the unadjusted ERR/Gy (95% CI) was increased for noncancer disease mortality (1.22, 0.10-3.14), but not for solid cancer mortality (- 0.18, < - 0.77-0.95); the unadjusted ERR/Gy for external cause mortality was not statistically significant (0.28, < - 0.60-2.36). Among females, the unadjusted ERRs/Gy were increased for solid cancer (2.24, 0.44-5.58), noncancer (2.86, 0.56-7.64), and external cause mortality (2.57, 0.20-9.19). The ERRs/Gy adjusted for potential mediators did not change appreciably for solid cancer mortality, but decreased notably for noncancer mortality (0.39, < - 0.43-1.91 for males; 1.48, - 0.046-4.55 for females) and external cause mortality (0.10, < - 0.57-1.96 for males; 1.38, < - 0.46-5.95 for females). In conclusion, antenatal radiation exposure is a consistent risk factor for increased solid cancer mortality among females, but not among males. The effect of exposure to atomic bomb radiation on noncancer disease and external cause mortality among individuals exposed in utero was mediated through small head size, low birth weight, and parental loss.

Urethrographic examinations: Patient and staff exposures and associated radiobiological risks

Medical exposure of the general population due to radiological investigations is the foremost source of all artificial ionising radiation. Here, we focus on a particular diagnostic radiological procedure, as only limited data are published with regard to radiation measurements during urethrograpic imaging. Specifically, this work seeks to estimate patient and occupational effective doses during urethrographic procedures at three radiology hospitals. Both staff and patient X-ray exposure levels were calculated in terms of entrance surface air kerma (ESAK), obtained by means of lithium fluoride thermoluminescent dosimeters (TLD-100(LiF:Mg:Cu.P)) for 243 urethrographic examinations. Patient radiation effective doses per procedure were estimated using conversion factors obtained from the use of Public Health England computer software. In units of mGy, the median and range of ESAK per examination were found to be 10.8 (3.6-26.2), 7.0 (0.2-32.3), and 24.3 (9.0-32.0) in Hospitals A, B, and C, respectively. The overall mean and range of staff doses (in µGy) were found to be 310 (4.0-1750) per procedure. With the exception of hospital C, the present evaluations of radiation dose have been found to be similar to those of previously published research. The wide range of patient and staff doses illustrate the need for radiation dose optimisation.

Eye lens and thyroid gland radiation exposure for patients undergoing brain computed tomography examination

This study aims to estimate the effective radiation dose and organ dose from head CT procedures. It was conducted in three main private hospitals in Khartoum State-Sudan, using Toshiba machines with 64 slices. The total number of patients included in this study was 142 patients (82 males and 60 females). The effective dose and organ dose were calculated by CT Expo software. The effective dose slightly varied among patients according to gender and age. The effective dose for female patients (5.99 mSv) was higher than that for male patients (5.84 mSv), and the pediatric dose (5.46 mSv) was lower than the adults' dose (5.94 mSv). The dose for eye lens was found lower for male patients (89.117 mSv) than the dose for female patients (94.62) mSv). According to patients' age: the dose received by the lens of the eye was much lower in pediatric (79.93 mSv) than the adults (92.41 mSv). The dose for thyroid in female patients (33.52 mSv) was higher than the male patients (28 mSv). The pediatric dose (28.34 mSv) was lower than the adults' dose (30.64 mSv). Departmental imaging protocol and lack of training among hospital staff are expected to be responsible for these variations. Therefore, this study recommends that the CT technologists be trained on suitable strategies to achieve dose optimization. Moreover, patients' doses must be monitored regularly.

Radiation risk for patients undergoing cardiac computed tomography examinations

The various technological advancements in computed tomography (CT) have resulted in remarkable growth in the use of CT imaging in clinical practice, not the least of which has been its establishment as the most valuable imaging examination for the assessment of cardiovascular system disorders. The objective of this study was to assess the effective radiation dose and radiation risk for patients during cardiac CT procedures, based on studies from four different hospitals equipped with 128 slice CT equipment. A total of eighty-three patients were investigated in this study with different clinical indications. Effective doses were also calculated using software based on Monte Carlo simulation. The mean patient age (years), weight (kg), and body mass index (BMI (kg/m²)) were 49 ± 11, 82 ± 12, and 31 ± 6, respectively. The results of the study revealed that the tube voltage (kVp) and tube current-exposure time product (mAs) ranged between 100 to 140 and 50 to 840 respectively. The overall average patient dose values for the volume CT dose index [(CTDI_vol), in mGy)] and dose length product (DLP) (in mGy·cm) were 34.8 ± 15 (3.7-117.0) and 383.8 ± 354 (46.0-3277.0) respectively. The average effective dose (mSv) was 15.2 ± 8 (1.2-61.8). The radiation dose values showed wide variation between different hospitals and even within the same hospital. The results indicate the need to optimize radiation dose and to establish diagnostic reference levels (DRLs) for patients undergoing coronary computed tomography angiography (CCTA), also to harmonize the imaging protocols to ensure reduced radiation risk.

ProZES: the methodology and software tool for assessment of assigned share of radiation in probability of cancer occurrence

ProZES is a software tool for estimating the probability that a given cancer was caused by preceding exposure to ionising radiation. ProZES calculates this probability, the assigned share, for solid cancers and hematopoietic malignant diseases, in cases of exposures to low-LET radiation, and for lung cancer in cases of exposure to radon. User-specified inputs include birth year, sex, type of diagnosed cancer, age at diagnosis, radiation exposure history and characteristics, and smoking behaviour for lung cancer. Cancer risk models are an essential part of ProZES. Linking disease and exposure to radiation involves several methodological aspects, and assessment of uncertainties received particular attention. ProZES systematically uses the principle of multi-model inference. Models of radiation risk were either newly developed or critically re-evaluated for ProZES, including dedicated models for frequent types of cancer and, for less common diseases, models for groups of functionally similar cancer sites. The low-LET models originate mostly from the study of atomic bomb survivors in Hiroshima and Nagasaki. Risks predicted by these models are adjusted to be applicable to the population of Germany and to different time periods. Adjustment factors for low dose rates and for a reduced risk during the minimum latency time between exposure and cancer are also applied. The development of the methodology and software was initiated and supported by the German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU) taking up advice by the German Commission on Radiological Protection (SSK, Strahlenschutzkommission). These provide the scientific basis to support decision making on compensation claims regarding malignancies following occupational exposure to radiation in Germany.

Estimation of various radiological parameters associated with radioactive contents emanating with fly ash from Sahiwal coal-fuelled power plant, Pakistan

The release of natural radioactive materials with the emission of fly ash as a result of coal burning in power generation plants is considered amongst the sources that elevate the technologically environmental radioactivity level. This research mainly concerns the assessment of various radiological parameters including excess lifetime cancer risk due to natural radioactive contents associated with fly ash emitted to the surrounding environment from the stack of 1320 Mw Sahiwal coal-fuelled power generation plant (CFPP). For this purpose, fifty-four soil samples were collected in a radius of 4 Km from CFPP and a highly background radiation-shielded HPGe system is used to measure radioactivity in the collected samples. The activity concentrations of radium-226, potassium-40, and thorium-232 in collected samples was found to be in the range of 20 to 138, 43 to 860, and 27 to 127 Bq/kg with average values of 66, 409, and 67 Bq/kg respectively. Activity concentrations of radium-226 and thorium-232 were observed significantly higher than UNSCEAR reported typical global average values. A significant decrease in the level of the aforementioned radionuclides in the collected soil samples was observed with increasing distance from the power plant, which is a clear indication for the elevation of radioactivity concentrations in the surrounding environment as a result of the operation of the CFPP. To assess the radiation dose delivered to the occupational workers and inhabitants living next to Sahiwal CFPP, absorbed γ-dose rate (D_γ), outdoor annual effective dose rate (E_Outdoor), and excess lifetime cancer risk (ELCR) were estimated and these were found higher than the UNSCEAR recommended values of 59 nGy/h, 0.07 mSv/y, and 2.9 × 10^-4 respectively. The outcome of this first systematic study is the assessment of potential radiological health risk to the occupational workers as well as the inhabitants living in the proximity of this CFPP.

Patients Radiation Risks from Computed Tomography Lymphography

Objectives:

This study aims to first measure patient doses during computed tomography (CT) chest, abdomen, and extremities procedures for evaluation lymphedema, and second to estimate the radiation dose-related risks during the procedures.

Material and Methods:

Radiation effective doses from CT lymphography procedures quantified using CT machines from different vendors. After the calibration of CT systems, the data collected for a total of 28 CT lymphography procedures. Effective and organ doses extrapolated using national radiological protection software based on Monte Carlo simulation.

Results:

The mean patient doses for chest and abdomen procedures in term of CTDIvol (mGy) and DLP (mGy.cm) are 10.0 ± 3 and 425 ± 222 and 24 ± 12 and 1118 ± 812 for CT 128 and CT 16 slice, respectively. The mean DLP (mGy.cm) for extremities was 320 ± 140 and 424 ± 212 for CT 128 and CT 16 slice, in that order.

Conclusion:

Patients’ dose showed significant differences due to variation in the scan length and clinical indication. Organs lay in the primary beam received high radiation doses especially in the chest region which increases the probability of radiation-induced cancer. The current patient’s doses are higher compared to the previous studies.

Do we really need the "detriment" for radiation protection?

The purpose of the ICRP detriment concept is to enable a quantitative comparison of stochastic radiation damage for the various organs. For this purpose, the organ-specific nominal risk coefficients are weighted with a function that is intended to express the amount of damage or, respectively, the severity of a disease. This function incorporates a variety of variables that do not depend on radiation parameters, but on characteristics of the disease itself. The question is raised as to whether the rather subtle way of defining the amount of damage is necessary for radiation protection purposes and whether a much simpler relationship can serve for this purpose as well or even better.

CRaTER observations and permissible mission duration for human operations in deep space

Prolonged exposure to the galactic cosmic ray (GCR) environment is a potentially limiting factor for manned missions in deep space. Evaluating the risk associated with the expected GCR environment is an essential step in planning a deep space mission. This requires an understanding of how the local interstellar spectrum is modulated by the heliospheric magnetic field (HMF) and how observed solar activity is manifested in the HMF over time. While current GCR models agree reasonably well with measured observations of GCR flux on the first matter, they must rely on imperfect or loose correlations to describe the latter. It is more accurate to use dose rates directly measured by instruments in deep space to quantify the GCR condition for a given period of time. In this work, dose rates observed by the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) instrument are used to obtain the local GCR intensity and composition as a function of time. A response function is constructed that relates observed dose rates to solar modulation potential using a series of Monte Carlo radiation transport calculations. The record of observed solar modulation potential vs. time is then used to calculate a recent historical record of permissible mission duration (PMD) according to NASA's permissible exposure limits (PEL). Tables are provided for extreme values of PMD. Additional tables include risk of exposure-induced death (at upper 95% confidence interval) accrual rates and NASA effective dose rates as a function of solar modulation potential, astronaut age, sex, and shielding thickness. The significance of the PMD values reported in relation to likely transit duration requirements for future exploration missions is discussed. There is general agreement between CRaTER observations and the prescription of solar modulation vs. time given by the Badhwar-O'Neill 2014 GCR model. However, CRaTER observations do capture the effects of significant heliospheric transients, among other features, that are missing from the prescription of solar modulation potential vs. time.

A randomized comparison of estimated radiation exposure between Low and conventional dose protocol during invasive coronary angiography (ERICA trial): Pilot study

PURPOSE

Radiation exposure during coronary angiography is potentially harmful to patients and operators. However, there are limited data on the effects of a low-dose radiation angiography. We evaluated the feasibility and effectiveness of a reduced radiation dose protocol during invasive coronary angiography.

METHODS

One hundred three consecutive patients who underwent coronary angiography were enrolled and randomized to low- or conventional dose protocols (LDP versus CDP). The LDP consists of 10 frames per second during fluoroscopy and half the radiation dose of CDP during cineangiography. Image quality was assessed using a Likert rating scale by an independent radiologist. The radiation dose was estimated with dose-area product (DAP) and air-kerma (AK).

RESULTS

Body weight and waist circumference are well correlated with the level of DAP and AK. Exposure time and total images and frame counts in cineangiography were similar in both groups. There was a marked reduction of the estimated radiation dose (DAP and AK) in the LDP group compared to the CDP group without significant compromise in image quality (total DAP: LDP 1980.1 ± 1163.7 vs. CDP 3434.2 ± 2188.1 μGym² p = 0.001; total AK: 279.6 ± 159.3 vs. 493.8 ± 280.6 mGy, p < 0.001).

CONCLUSION

The LDP reduced the total estimated radiation dose compared to the CDP without a significant loss of diagnostic information. A LDP may be a viable strategy to protect patients and medical staff from the hazards of radiation in the cardiac catheterization laboratory.

Individual response of humans to ionising radiation: governing factors and importance for radiological protection

Tissue reactions and stochastic effects after exposure to ionising radiation are variable between individuals but the factors and mechanisms governing individual responses are not well understood. Individual responses can be measured at different levels of biological organization and using different endpoints following varying doses of radiation, including: cancers, non-cancer diseases and mortality in the whole organism; normal tissue reactions after exposures; and, cellular endpoints such as chromosomal damage and molecular alterations. There is no doubt that many factors influence the responses of people to radiation to different degrees. In addition to the obvious general factors of radiation quality, dose, dose rate and the tissue (sub)volume irradiated, recognized and potential determining factors include age, sex, life style (e.g., smoking, diet, possibly body mass index), environmental factors, genetics and epigenetics, stochastic distribution of cellular events, and systemic comorbidities such as diabetes or viral infections. Genetic factors are commonly thought to be a substantial contributor to individual response to radiation. Apart from a small number of rare monogenic diseases such as ataxia telangiectasia, the inheritance of an abnormally responsive phenotype among a population of healthy individuals does not follow a classical Mendelian inheritance pattern. Rather it is considered to be a multi-factorial, complex trait.

Pediatric radiologist-driven didactics for a pediatric residency program: a quality initiative

BACKGROUND

Pediatric residents exhibit knowledge gaps in appropriateness of imaging utilization.

OBJECTIVE

This study evaluates the value of radiologist-driven imaging education in a pediatric residency program. The primary goals of this educational program were to provide pediatric residents with resources such as the American College of Radiology Appropriateness Criteria, support optimal resource utilization and patient care, increase resident understanding of radiation risk, and determine the value of integrating radiologists into pediatric education.

MATERIALS AND METHODS

A needs assessment was performed in which the chief residents of a large pediatric program were surveyed. The consensus of chief residents was that a four-part lecture series delivered by a pediatric radiology fellow would be beneficial to the pediatric residents. Topics included general radiation risk as well as basic imaging topics in the chest, abdomen, neurological system, extremities and vasculature. Each lecture integrated appropriate ordering, ALARA (As Low As Reasonably Achievable)/Image Gently, and basic image interpretation. Residents were asked, using a Likert scale, to rate their understanding of radiation risk, the ACR Appropriateness Criteria, and other topics of interest before and after each lecture. Pediatric residents were given a 10-item quiz before and after the lecture series to assess their knowledge regarding the best test to order in clinical scenarios.

RESULTS

The average pre-lecture score for knowledge of radiation risk was 3.27 (95% confidence interval [CI]: 3.02-3.51) out of 5, which improved to 4.27 (95% CI: 4.09-4.57) post-lecture. There was an increase in understanding of ACR appropriateness, with pre-lecture rating of knowledge increasing from 1.91 (95% CI 1.54-2.29) out of 5 to 3.61 (95% CI 3.33-3.90) post-lecture. The residents averaged 82.7% (95% CI 77.3%-88.1%) on the appropriateness pre-test and 93.8% (95% CI 90.3%-97.2%) on the post-test. Residents provided positive feedback upon conclusion of the program and reported a beneficial effect on their education.

CONCLUSION

A radiologist-driven lecture series in a pediatric residency can improve resident understanding of appropriate ordering practices and radiation risk. Radiologist participation in pediatric residency training is well-received.

CT scan exposure in children with ventriculo-peritoneal shunts: single centre experience and review of the literature

PURPOSE

A computed tomography (CT) scan in childhood is associated with a greater incidence of brain cancer. CT scans are used in patients with ventriculo-peritoneal (VP) shunts in whom shunt dysfunction is suspected. We wanted to assess the CT scan exposure in a cohort of children with VP shunts and attempt to quantify their radiation exposure.

METHODS

A single-centre retrospective analysis was performed recording CT head scans in children younger than 18 years with VP shunts. Hospital coding data was cross-referenced with electronic records and radiology databases both in our neurosurgery unit and in hospitals referring to it.

RESULTS

One hundred and fifty-two children with VP shunts were identified. The mean time with shunt in situ was 5.4 years (± 4.61). A mean of 3.33 CT scans (range 0-20) were performed on each child, amounting to 0.65 (± 0.87) CTs per shunt year. Based on 2 msv of radiation per scan, this equates to an average exposure of 1.31 msv per child per shunt year.

CONCLUSION

Children who have multiple CT head scans for investigation of possible shunt dysfunction are at a greater risk of developing cancer. We discuss the implications of this increased risk and discuss strategies to limit radiation exposure in children with VP shunts.

Association of radiation risk in the second and third generations with polymorphisms in the genes CYP1A1, CYP2E1, GSTP1 and changes in the thyroid

Background

To study the association of radiation risk in the 2nd –3rd generations with polymorphisms in the genes CYP1A1, CYP2E1, GSTP1 and changes in the thyroid.

Methods

5 polymorphic gene variants (rs1048943, rs4646421, rs2070676, rs3813867, rs1695) were studied in 399 people living in the East Kazakhstan region in this research. 248 people of the 2nd - 3rd generation lived in the territory with radiation exposure in Abai, Borodulikha areas, and 151 people the comparison group lived in Kurchum district without radiation exposure comparable in sex and age with control group.

Results

The results show that there is a significant association of rs1048943 in exposed and unexposed groups (p < 0.003), and the absence of association of rs4646421, rs2070676, rs3813867, rs1695 in the studied groups. The mean value of thyroxine in carriers of the AG + GG genotype of rs4646421 is significantly lower than in AA genotype carriers (p = 0.04); no significant changes were found in genotypes’ distribution with thyroid-stimulating hormone and anti-thyroid peroxidase indicators. Significant changes were in levels of anti-thyroid peroxidase between exposed and unexposed groups (p = 0.007). The thyroxine - thyroid-stimulating hormone levels were not significantly different in exposed and unexposed groups (p > 0.3).

Conclusions

This study demonstrated the association of rs1048943 polymorphism with living in the radiation zone in the 2nd and 3rd generations for the first time. Thyroxine levels decrease was identified in the 2nd and 3rd generation residents of the exposed area, as well as a significant increase of anti-thyroid peroxidase occurs in individuals of the 2nd and 3rd generation living in areas with radiation exposure.

Physicians' exposure to radiation during electrophysiology procedures

PURPOSE

Cardiologists are among the health professionals that are most exposed to ionizing radiation, but there is no study comparing the level of exposure of physicians during different electrophysiology procedures. We aimed to measure and compare cardiologists' exposure to radiation during different electrophysiology procedures.

METHODS

The study population comprised all electrophysiology procedures performed over a 6-month period in a large referral centre. The endpoint was operator radiation exposure, assessed using a personal electronic dosimeter located on the operator's left arm.

RESULTS

In total, 150 electrophysiology procedures were analyzed. Compared with electrophysiology studies (reference category), physician radiation exposure was 3-fold greater during ablation of atrial fibrillation, 9-fold greater during ablation of atrioventricular nodal reentrant tachycardia (AVNRT)/atrioventricular reentrant tachycardia (AVNT), and 10-fold greater during ablation of atrial flutter (p < 0.001). Physician exposure was mainly related to X-ray time (R² = 0.28).

CONCLUSIONS

Our study showed significant differences in cardiologists' exposure to ionizing radiation depending on the type of electrophysiology procedure. Atrial flutter and AVNRT/AVNT ablations are the procedures in which operators are most exposed to ionizing radiation.

Looking for solutions: vision and a call-for-attention for radiation research scientists

Purpose: The concept of benefit-risk assessment has often been propagated for clinical professionals for deciding the radiological exam for the patient. A detailed look into how to use this concept leads to several unanswered questions. The purpose of this article is to bring forth questions which have remained unanswered for several decades. These questions pertain to our inability to provide needed information to physicians for making benefit-risk assessment for deciding a frequent imaging modality like the computed tomography (CT) such as non-applicability of risk estimates to an individual patient, the concept of cumulative risk at low doses, accounting for the time gap between series of CT scans, risk variation with age, gender and disease condition. In the absence of concrete information on these, it becomes essentially benefit assessment rather than benefit-risk. The article also provides a motivation to think that there are a large number of patients getting exposed every year to radiation doses over 100 mSv of effective dose and several tens of mGy of organ doses. This may provide a very large cohort for radiation effect studies. Further, a series of ideas are presented as a vision for future studies. Conclusions: The article emphasizes the need to create a research agenda to deal with day-to-day questions faced in medical practice and provides a call-for-attention. Further, it provides some challenging ideas as outside of the box thinking points that may provide research direction for future years.

Radiation Risk Categories in Cardiac Catheterization for Congenital Heart Disease: A Tool to Aid in the Evaluation of Radiation Outcomes

To stratify diverse procedure types into categories with similar radiation exposure in cardiac catheterization for congenital heart disease. Radiation exposures for a comprehensive list of specific procedure types and stratification of outcomes based on radiation risk are not currently available. Data between January 2014 and December 2015 were collected on all cases performed at sites participating in C3PO-QI (Congenital Cardiac Catheterization Outcomes Project-Quality Improvement Initiative) and 9 centers were included. Using expert consensus, 40 unique procedure types were defined by diagnostic characteristics or the intervention(s) performed, and dose area product (DAP) per kilogram of body weight (µGy × m²/kg) was summarized. Using empiric and consensus methods, three radiation risk categories were created. A total of 11,735 cases were included for analysis. Thirteen (n = 7918) procedure types with median DAP/kg < 100 were categorized in the low radiation exposure category (median DAP/kg 39). The medium exposure category (n = 1807) consisted of 16 procedure types with median DAP/kg values ranging 100 to < 200 (overall median DAP/kg 131). Finally, the high radiation exposure category (n = 1073) consisted of 11 procedure types with median DAP/kg ≥ 200 (overall median DAP/kg of 231). The radiation exposure risk categories created in this multi-center dataset are a critical step towards the development of a robust risk adjustment methodology for radiation exposure in catheterization for congenital heart disease.

Increased prevalence of essential hypertension in areas previously exposed to fallout due to nuclear weapons testing at the Semipalatinsk Test Site, Kazakhstan

This study examines the association between environmental radiation exposure and essential hypertension in a series of investigated geographical districts adjacent to the Semipalatinsk nuclear test site in Kazakhstan. The sample consists of 2000 volunteers participants in screening examinations in three administrative districts close to the nuclear test site, which was carried out as part of the Government Programs on Environmental Health Hazard. The cross-sectional study compares prevalence ratios in a population sample with long-term exposure in the low and intermediate dose range. Age-adjusted odds ratios for hypertension were found significantly increased with higher exposure groups. After accounting for main cardiovascular risk factors into the model and stratifying by gender, the prevalence odds ratios for radiation remained significantly increased, with a significant dose-response effect observed for some but not all subgroups. The results support existing evidence of cardiovascular health effects of radiation exposure and of persisting environmental health issues that require attention in both epidemiological surveys and healthcare provision.