Collective effective dose in Europe from X-ray and nuclear medicine procedures

Evaluation of organ dose using size-specific dose estimation (SSDE) and related cancer risk due to chest CT scan during the COVID-19 pandemic

This study aimed to estimate lung and breast doses for individual patients using the size-specific dose estimate (SSDE) method, as well as calculating effective doses, in patients who underwent chest CT scans during the COVID-19 pandemic. Cancer risk incidence was estimated using excess relative risk (ERR), excess absolute risk (EAR), and lifetime attributable risk (LAR) models from the Biological Effects of Ionizing Radiation Report VII (BEIR-VII). Data from about 570 patients who underwent CT scans for COVID-19 screening were utilized for this study. Using the header of the CT images in a Python script, SSDE and effective dose were calculated for each patient. The SSDE obtained by water equivalent effective diameter (wSSDE) was considered as lung and breast dose, and applied in organ-specific cancer risk estimation. The mean wSSDE value for females (13.3 mGy) was slightly higher than that for males (13.1 mGy), but the difference was not statistically significant (P value = 0.41). No significant differences were observed between males and females in terms of calculated EAR and ERR for lung cancer at 5 and 30 years after exposure (P value = 0.47, 0.46, respectively). Similarly, there was no significant difference in lung cancer LAR values between females and males (P value = 0.48). The results also indicated a decrease in LAR values for both lung and breast cancers with increasing exposure age. In accordance with the ALARA (as low as reasonably achievable) principle, it is important for medical staff and the general public to consider the benefits of CT imaging in detecting such infections. Additionally, imaging medical physicists and CT scan experts should optimize imaging protocols and strike a balance between image quality for detecting abnormalities and radiation dose, all while adhering to the ALARA principle.

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.

Radiation exposure by medical X-ray applications

Background: Radioactive material and ionising radiation play a central role in medical diagnostics and therapy. The benefit of ionising radiation is opposed by the risk of irreparable damage of the human organism. This risk, especially for developing malign neoplasms, has particularly been investigated in the population surviving the atomic bombing of Hiroshima and Nagasaki, but also increasingly in persons with occupational or medical exposure to ionising radiation.

Methods: We conducted a systematic search for publications in English and German in relevant databases in March 2016. Retrievals were screened by two independent reviewers. We included examinations using imaging procedures with ionising radiation. The assessment of methodological quality was done concerning representativeness, risk of bias, and further limitations, and reporting quality was assessed using the RECORD checklist.

Results: The systematic searches identified seven cross-sectional, one register, and four cohort studies. An increase in collective effective doses analogue to the increase of computed tomography (CT) examinations could be observed. An increased risk of brain tumours in children after exposition to head CT and by an increase of the number of examinations was shown. For children with predisposing factors, an increased risk of tumours of the central nerve system, leukemia, and lymphoma was found. Furthermore, a general risk for malign neoplasms or haemoblastoma, and a specific risk for lymphoma after CT examinations of different parts of the body could be observed.

Discussion: Taking into consideration a mostly unclear representativeness of studies and an unclear or high risk of bias as well as lack of comparability due to different research questions, the validity of results is limited.

Conclusion: The risk of bias due to a large number of reference sources must be reduced in studies leading to realistic estimates of collective radiation doses. The risk of CT-induced radiation exposure for children should be investigated by further studies with a follow-up of at least ten years.

CONTEMPORARY COLLECTIVE EFFECTIVE DOSE TO THE POPULATION FROM X-RAY AND NUCLEAR MEDICINE EXAMINATIONS-CHANGES OVER LAST 10 YEARS IN FINLAND

Contemporary collective effective doses to the population from x-ray and nuclear medicine examinations in Finland in 2018 was estimated. The estimated effective dose per caput from x-ray examinations increased from year 2008 to 2018 respectively from 0.45 mSv to 0.72 mSv and from nuclear medicine examinations from 0.03 mSv to 0.04 mSv. The proportional dose due to CT examinations of the total collective effective dose from all x-ray examinations increased from 58% in 2008 to 70% in 2018 and the dose did not change substantially in total when new conversion factors were applied. The collective effective dose from conventional plain radiography did not change substantially during the last ten years while the new (ICRP 103) tissue weighting factors were taken into use in 2018, however frequencies of examinations in total decreased. The collective effective dose from CT in nuclear medicine tripled between 2009 and 2018.

Diagnostic Nuclear Medicine for Paediatric Patients in Australia: Assessing the Individual's Dose Burden

We report data for all Australians aged 0-19 y who underwent publicly funded nuclear medicine studies between 1985 and 2005, inclusive. Radiation doses were estimated for individual patients for 95 different types of studies. There were 374 848 occasions of service for 277 511 patients with a collective effective dose of 1123 Sievert (Sv). Most services were either bone scans (45%) or renal scans (29%), with renal scans predominating at younger ages and bone scans at older ages. This pattern persisted despite a 4-fold increase in the annual number of procedures. Younger children were more likely to experience multiple scans, with the third quartile of scans per patient dropping from two to one with patient age. The median effective dose per patient ranged from 1.3 mSv (4-7 y old) to 2.8 mSv (13-16 y old). This large data set provides valuable information on nuclear medicine services for young Australians in the period 1985-2005.

Does clinical indication play a role in CT radiation dose in pediatric patients?

PURPOSE

The purpose of this study was to identify the main pathologies for which CT is applied on pediatric patients and the related radiation doses as reported in the literature in order to facilitate justification and CT optimization.

METHODS

A critical analysis of a literature review was performed. Different search engines were used such as PubMed, Google Scholar and Science Direct. Various terms and keywords were used to locate pertinent articles such as Pediatric, Computed tomography, Radiation Dose, Organ dose, Effective dose.

RESULTS

The results showed that the main pathologies for which CT is applied are: Crohn's disease, hydrocephalus, cystic fibrosis and pediatric malignancies-mainly lymphoma. The related radiation dose data are extremely scarce and are in the range of 3.48-17.56, 0.2-15.3mSv, 0.14-6.20mSv, and 2.8-518.0mSv, respectively. The radiation doses reported are high especially in pediatric oncology.

CONCLUSIONS

Pediatric patients with malignancies are those exposed to the higher levels of radiation during CT imaging. Literature is lacking reporting of dose in Pediatric CT imaging. More studies need to be realized for the determination of radiation dose in those patients. Special protocols need to be recommended in order to reduce the exposure of children in radiation.

Radiation Dose from Whole-Body F-18 Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography: Nationwide Survey in Korea

The purpose of this study was to estimate average radiation exposure from (18)F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) examinations and to analyze possible factors affecting the radiation dose. A nation-wide questionnaire survey was conducted involving all institutions that operate PET/CT scanners in Korea. From the response, radiation doses from injected FDG and CT examination were calculated. A total of 105 PET/CT scanners in 73 institutions were included in the analysis (response rate of 62.4%). The average FDG injected activity was 310 ± 77 MBq and 5.11 ± 1.19 MBq/kg. The average effective dose from FDG was estimated to be 5.89 ± 1.46 mSv. The average CT dose index and dose-length product were 4.60 ± 2.47 mGy and 429.2 ± 227.6 mGy∙cm, which corresponded to 6.26 ± 3.06 mSv. The radiation doses from FDG and CT were significantly lower in case of newer scanners than older ones (P < 0.001). Advanced PET technologies such as time-of-flight acquisition and point-spread function recovery were also related to low radiation dose (P < 0.001). In conclusion, the average radiation dose from FDG PET/CT is estimated to be 12.2 mSv. The radiation dose from FDG PET/CT is reduced with more recent scanners equipped with image-enhancing algorithms.

Estimating the population dose from nuclear medicine examinations towards establishing diagnostic reference levels

PURPOSE OF THE STUDY

This study conducted a review on nuclear medicine (NM) services in Mazandaran Province with a view to establish adult diagnostic reference levels (DRLs) and provide updated data on population radiation exposure resulting from diagnostic NM procedures.

MATERIALS AND METHODS

The data were collected from all centers in all cities of Mazandaran Province in the North of Iran from March 2014 to February 2015. The 75(th) percentile of the distribution and the average administered activity (AAA) were calculated and the average effective dose per examination, collective effective dose to the population and annual effective dose per capita were estimated using dose conversion factors. The gathered data were analyzed via SPSS (version 18) software using descriptive statistics.

RESULTS

Based on the data of this study, the collective effective dose was 95.628 manSv, leading to a mean effective dose of 0.03 mSv per capita. It was also observed that the myocardial perfusion was the most common procedure (50%). The 75(th) percentile of the distribution of administered activity (AA) represents the DRL. The AAA and the 75(th) percentile of the distribution of AA are slightly higher than DRL of most European countries.

CONCLUSIONS

Myocardial perfusion is responsible for most of the collective effective dose and it is better to establish national DRLs for myocardial perfusion and review some DRL values through the participation of NM specialists in the future.