Diagnostic reference levels for common computed tomography (CT) examinations: results from the first Nigerian nationwide dose survey

Multicenter, international study of CT practices and radiation doses from 10 African countries: An International Atomic Energy Agency (IAEA) baseline study

PURPOSE

The objective of our IAEA-coordinated international study was to assess CT practices and radiation doses from multiple hospitals across several African countries.

METHODS

The study included 13 hospitals from Africa which contributed information on minimum of 20 consecutive patients who underwent head, chest, and/or abdomen-pelvis CT. Prior to the data recording step, all hospitals had a mandatory one-hour training on the best practices in recording the relevant data elements. The recorded data elements included patient age, weight, protocol name, scanner information, acquisition parameters, and radiation dose descriptors including phase-specific CT dose index volume (CTDIvol in mGy) and dose length product (DLP in mGy.cm). We estimated the median and interquartile range of body-region specific CTDIvol and DLP and compared data across sites and countries using the Kruskal-Wallis H Test for non-normal distribution, analysis of variance.

RESULTS

A total of 1061 patients (mean age 50 ± 19 years) were included in the study. 16 % of CT exams had no stated clinical indications for CT examinations of the head (32/343, 9 %), chest (50/281, 18 %), abdomen-pelvis (67/243, 28 %), and/or chest-abdomen-pelvis CT (24/194, 12 %). Most hospitals used multiphase CT protocols for abdomen-pelvis (9/11 hospitals) and chest CT (10/12 hospitals), regardless of clinical indications. Total median DLP values for head (953 mGy.cm), chest (405 mGy.cm), and abdomen-pelvis (1195 mGy.cm) CT were above the UK, German, and American College of Radiology Diagnostic Reference Levels (DRLs).

CONCLUSIONS

Concerning variations in CT practices and protocols across several hospitals in Africa were demonstrated, emphasizing the need for better protocol optimization to improve patient safety.

An Analysis of Computed Tomography Diagnostic Reference Levels in India Compared to Other Countries

Computed Tomography (CT) is vital for diagnosing and monitoring medical conditions. However, increased usage raises concerns about patient radiation exposure. Diagnostic Reference Levels (DRLs) aim to minimize radiation doses in CT imaging. This study examines CT DRLs in India compared to other countries to identify optimization opportunities. A literature review was conducted to gather data from published studies, guidelines, and regulatory authorities. Findings show significant international variations in CT DRLs, with differences up to 50%. In India, DRLs also vary significantly across states. For head CT exams, Indian DRLs are generally 20-30% lower than international standards (27-47 mGy vs. 60 mGy). Conversely, for abdominal CT scans, Indian DRLs are 10-15% higher (12-16 mGy vs. 13 mGy). Factors influencing DRL variations include equipment differences, imaging protocols, patient demographics, and regulatory conditions. Dose-optimization techniques like automatic exposure control and iterative reconstruction can reduce radiation exposure by 25-60% while maintaining image quality. Comparative data highlight best practices, such as the United Kingdom's 30% reduction in CT doses from 1984 to 1995 via DRL implementation. This study suggests that adopting similar practices in India could reduce radiation doses by 20-40% for common CT procedures, promoting responsible CT usage and minimizing patient exposure.

Radiation doses and diagnostic reference levels for common CT scans in adults in Northwest region of Iran

This study aims to estimate organ dose and cancer risks, establish region-specific diagnostic reference levels (DRLs), and determine achievable doses (ADs) for common CT procedures in adults in the northwest of Iran. Effective and organ doses were estimated using VirtualDoseCT software in a sample of 480 adult patients who underwent head, sinus, chest, and abdomen-pelvis (AP) CT scans. The guidelines provided by the BEIR VII report were utilized to estimate cancer risks. Effective and organ doses for specific procedures were determined, with the highest mean organ dose being observed in the brain during head CT examinations, with a value of 54.02 mGy. It was observed that the lungs in chest examinations and the colon in AP examinations had the highest risk of cancer, with rates of 30.72 and 21.37 per 100,000 persons, respectively. Higher cancer risk values were generally exhibited by females compared to males. The DRLs for common CT examinations were established as follows: Head CT (CTDIvol 41 mGy, DLP 760 mGy cm), Sinus CT (CTDIvol 16 mGy, DLP 261 mGy cm), Chest CT (CTDIvol 8 mGy, DLP 287 mGy cm), and AP CT (CTDIvol 9 mGy, DLP 508 mGy cm). Significant variations in dose distribution among facilities were identified, indicating the need for optimization. The study highlights the importance of minimizing radiation exposure to critical organs and promoting patient safety in CT examinations. The establishment of region-specific DRLs and ADs can help optimize radiation doses and reduce cancer risks for patients.

Results and analysis of examination doses for paediatric CT procedures based on a nationwide survey in China

OBJECTIVE

To report the results of a dose survey conducted across 31 provinces in mainland China from 2017 to 2018 and to analyse the dose level to determine the national diagnostic reference levels (DRLs) for paediatric CT procedures.

METHODS

At least ten patients for each age group (0- < 1, 1- < 5, 5- < 10, 10- < 15 years) and each procedure (head, chest and abdomen) for each CT scanner were selected from four to eight hospitals in each province. The dose information (CTDIvol and DLP) was collected from the HIS or RIS-PACS systems. The median values in each CT scanner were considered the representative dose values for the paediatric patients in CT scanning. The national DRLs were estimated based on the 75th percentile distribution of the median values.

RESULTS

A total of 24,395 patients and 319 CT scanners were investigated across 262 hospitals. For paediatric CT scanning in 4 different age groups, the median (P50) and the 75th percentile (P75) of CTDIvol and DLP for each scanning procedure were calculated and reported. National DRLs were then proposed for each procedure and age group.

CONCLUSION

The dose level of CT scanning for children in mainland China was reported for the first time. The DRLs for paediatric CT in the present study are similar to those in some Asian countries but higher than those in European countries.

CLINICAL RELEVANCE STATEMENT

The paediatric CT is an extensively used tool in diagnosing paediatric disease; however, children are more sensitive to radiation. Establishing the diagnostic reference level of paediatric CT examination is necessary to reduce the dose of CT in children and promote the optimisation of medical exposure.

KEY POINTS

• The DRLs for 3 paediatric CT procedures (head, chest and abdomen) and 4 age groups (0- < 1, 1- < 5, 5- < 10, 10- < 15 years) were proposed in mainland China first time. • The examination parameter and dose for children need to be further optimised in China, especially to lower the tube voltage in paediatric CT.

Local Diagnostic Reference Levels for Common Adult Computed Tomography Procedures in Addis Ababa

Background

Computed Tomography has become the major source of population exposure in diagnostic x-rays. This concerned issue will be resolved by stetting Local Diagnostic Reference Levels.

Objectives

The main objective of this study is to assess dose indicators for the establishment of Local Diagnostic Reference Levels.

Materials and methods

A prospective cross-sectional study design was conducted on 8 public and private hospitals performing CT examinations. A total of 725 adult patients who underwent abdominopelvic, chest, and head CT examinations were evaluated from October 2021 to March 2022. Patients' demography, exposure parameters, and dose descriptors were collected. The minimum, maximum, mean, median, and third quartile values were analyzed using SPSS software version 26. Finally, the third quartile values of collected data were compared with national and international values.

Results

The third quartile values obtained from median of volumetric computed tomography dose index (mGy) and dose length product (mGy.cm) which are considered as local DRLs for head, chest, and abdominopelvic CT examination, respectively, were 53 mGy, 14 mGy and 13 mGy; 1307 mGy.cm, 575 mGy.cm, and 932 mGy.cm.

Conclusion

The results of this study showed that practices of CT imaging in both public and private hospitals in Addis Ababa were comparable to other national and international values.

Establishment of local diagnostic reference levels for common adult CT examinations: a multicenter survey in Addis Ababa

BACKGROUND

In medical imaging, a computed tomography (CT) scanner is a major source of ionizing radiation. All medical radiation exposures should be justified and optimized to meet the clinical diagnosis. Thus, to avoid unnecessary radiation doses for patients, diagnostic reference levels (DRLs) have been used. The DRLs are used to identify unusually high radiation doses during CT procedures, which are not appropriate for the clinical diagnosis. It has been successfully implemented in Europe, Canada, Australia, the United States, several industrialized countries, and a few underdeveloped countries. The present study aimed to establish DRLs for the head, chest, and abdominopelvic (AP) CT procedures in Addis Ababa, Ethiopia.

METHODS

A pilot study identified the most frequent CT examinations in the city. At the time of the pilot, eighteen CT scan facilities were identified as having functioning CT scanners. Then, on nine CT facilities (50% of functional CT scanners), a prospective analysis of volume CT dose index (CTDI_vol) and dose length product (DLP) was performed. We collected data for 838 adult patients' head, chest, and AP CT examinations. SPSS version 25 was used to compute the median values of the DLP and CTDI_vol dose indicators. The rounded 75th percentile of CTDI_vol and DLP median values were used to define the DRLs. The results are compared to DRL data from the local, regional, and international levels.

RESULT

The proposed DRLs using CTDI_vol (mGy) are 53, 13, and 16 for the head, chest, and AP examinations respectively, while the DLP (mGy.cm) for the respective examinations were 1210, 635, and 822 mGy.cm.

CONCLUSION

Baseline CT DRLs figures for the most frequently performed in Addis Ababa were provided. The discrepancies in dose between CT facilities and as well as between identical scanners suggests a large potential for dose optimization of examinations. This can be actually achieved through appropriate training of CT technologists and continuous dose audits.

Establishment of CT diagnostic reference levels (DRLs) for a Singapore healthcare cluster

INTRODUCTION

The use of computed tomography (CT) in healthcare institutions has increased rapidly in recent years. The Singapore Health Services (SingHealth) cluster of healthcare institutions has taken the first step in establishing a local cluster-wide CT Diagnostic Reference Levels (DRL) in Singapore. CT dose data from each institution were collected through two primary dosimetry metrics: volume CT dose index (CTDI_vol measured in mGy) and dose-length product (DLP measured in mGy.cm).

METHODS

Data from 19 CT scanners in seven institutions under one of Singapore healthcare cluster were retrospectively collected and analysed. The five common adult CT examinations analysed were CT Brain (non-contrast enhanced), CT Chest (IV contrast enhanced), CT Kidney-Ureter-Bladder (CT KUB, non-contrast enhanced), CT Pulmonary Angiogram (CT PA, IV contrast enhanced) and CT Abdomen-Pelvis (CT AP, IV contrast enhanced, single phase). Median CTDI_vol and DLP values for the five CT examinations from each institution were derived, with the cluster DRLs determined as the 75th percentile of the distribution of the institution median dose values.

RESULTS

A total of 2413 dose data points were collected over a six-month period from June to November 2020. The cluster CT DRLs for the five CT examinations were determined to be 47 mGy and 820 mGy.cm for CT Brain, 5.4 mGy and 225 mGy.cm for CT Chest, 6.7 mGy and 248 mGy.cm for CT PA, 4.6 mGy and 190 mGy.cm for CT KUB and 6.9 mGy and 349 mGy.cm for CT AP.

CONCLUSION

The establishment of the cluster CT DRLs provided individual institutions with a better understanding if their CT doses are unusually high or low, while emphasising that these DRLs are not meant as hard dose limits or constraints to follow strictly.

Adult Computed Tomography examinations in Uganda: Towards determining the National Diagnostic Reference Levels

INTRODUCTION

Diagnostic Reference Levels (DRLs), typically set at the 75th percentile of the dose distribution from surveys conducted across a broad user base using a specified dose-measurement protocol, are recommended for radiological examinations. There is a need to develop and implement DRLs as a standardisation and optimisation tool for the radiological protection of patients at Computed Tomography (CT) facilities.

METHODS

This was a retrospective cross-sectional study conducted in seven (7) different CT scan facilities in which participants were recruited by systematic random sampling. The study variables were dose length product (DLP) and volume-weighted CTDI (CTDIvol) for the radiation doses for head, chest, abdomen and lumbar spine CT examinations. The DRLs for CTDIvol and DLP were obtained by calculating the 3rd quartiles of the radiation doses per study site by anatomical region. The national diagnostic reference levels were determined by computation of DRLs using the 75th centile of the median values.

RESULTS

A total of 574 patients were examined with an average age of 47.1 years. For CTDIvol estimates; there was a strong positive significant relationship between the CTDIvol and examination mAs (r_s = 0.9017, p-value < 0.001), and reference mAs (r_s = 0.0.7708, p-value < 0.001). For DLP estimates; there was a moderate positive significant relationships between DLP and total mAs (r_s = 0.6812, p-value < 0.001), reference mAs (r_s = 0.5493, p-value < 0.001). The DRLs were as follows; for head CT scan - the average median CTDIvol was 56.02 mGy and the DLP was 1260.3 mGy.cm; for Chest CT, the CTDI volume was 7.82 mGy and the DLP was 377.0 mGy.cm; for the abdomen CT, the CTDI volume 12.54 mGy and DLP 1418.3 mGy.cm and for the lumbar spine 19.48 mGy and the DLP was 843 mGy.cm, respectively.

CONCLUSION

This study confirmed the need to optimize the CT scan parameters in order to lower the national DRLs. This can be achieved by extensive training of all the CT scan radiographers on optimizing the CT scan acquisition parameters. Continuous dose audits are also advised with new equipment or after every three years to ensure that values out of range are either justified or further investigated.

Thyroid dose and cancer risk from head and neck computed tomography at two selected centres in Nigeria

Objective

The objective of this study was to evaluate the thyroid glands' radiation dose and the risk of thyroid cancer induction from head or neck computed tomography (CT) examinations.

Methods

In a prospective study, we evaluated all participants of all ages and sex referred for Head or Neck CT Scan at the University College Hospital, Ibadan and Me Cure Healthcare Limited, Ibadan, Oyo State, Nigeria. Thyroid radiation dose was estimated with impact scan calculator, and real-time dose measurement with thermoluminescent badge dosimeters (TLDs). Data were analysed and P < 0.05 was considered statistically significant.

Results

One hundred and sixty-three participants (128 adults and 35 children) participated in the study. In most participants (74%), the tube voltage was 120 kVp. The estimated median thyroid gland dose by the imPACT scan calculator was 4.95 mGy (range = 1.20-30.0 mGy) and 4.40 mGy (range = 3.0-5.10 mGy), while the real-time dose measured by the TLD was 4.79 mGy (range = 1.73-96.7 mGy) and 2.33 mGy (range = 1.20-3.73 mGy) at Centre A and B, respectively. The estimated median thyroid cancer risk was 2.88 × 10^-6 (maximum range of 52 × 10^-6) at centre A and a median value of 3.20 × 10^-6 with a cancer risk estimate that may reach 17.9 × 10^-6 recorded at centre B, compared to a cumulative thyroid cancer risk of 0.12 × 10^-5 among the general Nigerian population.

Conclusions

Scanner specifications and technique may significantly contribute to variations seen in thyroid radiation doses. There may be a need to optimise centre protocols and apply dose reference levels for head and neck CT examinations to reduce thyroid cancer risk in Nigeria.

Assessment of diagnostic reference levels awareness and knowledge amongst CT radiographers

Background

Reports indicated that numerous factors, including inadequate personnel knowledge, contributes to insufficient patient data for setting up diagnostic reference levels (DRLs) in developing countries. This study aims to evaluate the knowledge of DRLs as an optimisation tool amongst computed tomography (CT) radiographers in northern Nigeria. This is a quantitative cross-sectional study. A structured questionnaire was devised and distributed on site to sixty-two CT radiographers in northern Nigeria. A total of fifteen questions were included in the questionnaire focusing on DRLs, dose optimisation and dose descriptors generating quantitative data concerning overall CT radiographers’ perceived knowledge and awareness about DRLs.

Results

A response rate of 77.4% (48/62) was achieved. About 83.3% of the participants declare DRLs awareness, and 37.5% carried out a local dose survey. The percentage correctly perceived knowledge of concepts; DRLs was 45.8%, dose optimisation (42%) and CT dose descriptor (39%). Radiographers with work experience ranging from 4-10 years had the highest score.

Conclusion

In this survey, deficiencies were noted in radiographers’ knowledge about DRLs with precise knowledge gap in the implementation of local dose survey for DRLs and optimisation. There is a need for continuous radiographers’ training with greater emphasis on dose optimisation and institutional based dose evaluation.

A Review of Diagnostic Reference Levels in Computed Tomography

Computed tomography (CT) scanning generate 3-D images of the inside structures of the body by delivering comparatively radiation dose to the patient. This requires high concern of optimization via establishing diagnostic reference level (DRL). DRL values can be estimated based on reference patient percentiles (such as 90th, 75th and 50th) dose distribution. DRL has significant uses in professional judgments by generating harmonized evidence about the radiation dose received by the patient. The primary goal of this review is to assess the practical application of DRL in CT procedures internationally. The main objective of establishing DRLs is to optimize the patient dose and without compromising the image quality in order to obtain adequate diagnostic information. That means inescapability of DRL for a country in medical diagnosis is to reduce the limitation of dose dispersion, to harmonize and expand good practice, to narrow large dispersion of doses, and to create systematic supervision for unwanted radiological doses. The review presents that international records have a wide-range of mean dose distributions due to the variation of exam protocols and technical parameters in use. Hence, this review recommends that each CT health facilities are required exercising careful dose reduction strategies by accounting adequate image quality with sufficient diagnostic information via through follow up of concerned bodies.

ESTABLISHING LOCAL DIAGNOSTIC REFERENCE LEVELS FOR ROUTINE COMPUTED TOMOGRAPHY EXAMINATIONS IN JIMMA UNIVERSITY MEDICAL CENTER SOUTH WEST ETHIOPIA

The main purpose of this study was to determine local diagnostic reference level (LDRL) for Routine Computed Tomography (CT) examination in, Jimma University Medical Center (JUMC) South West Ethiopia. Retrospective study was conducted to determine LDRL for routine CT examination in JUMC. We have considered CTDIvol and DLP as dosimetric quantity based on the recommended guidelines to determine LDRLs by different international legal Authorities. The 75th percentile values of the calculated CTDIvol and DLP were proposed as LDRL. LDRL was obtained as CTDIvol, 42.97mGy, 7.76mGy, 14.32mGy, and 10.86mGy for routine brain CT, routine chest CT, routine thoraco-lumbar CT and routine abdomen CT examination respectively. Similarly the determined LDRL from DLP was 1364.15mGycm, 368.96mGycm, 853.18mGycm, and 1568.96mGycm for brain, chest, thoraco-lumbar and abdomen examination respectively. The LDRL obtained for DLP was higher compared with international DRLs; it can be reduced by coordinating effort between radiologists, technologists and medical physicist.

Risk of Hematologic Malignant Neoplasms From Abdominopelvic Computed Tomographic Radiation in Patients Who Underwent Appendectomy

Importance

Whether computed tomography (CT) radiation is truly carcinogenic remains controversial. Large epidemiological studies that purportedly showed an association between CT radiation and carcinogenesis were limited by confounding by indication and reverse causation, because the reasons for CT examination were unknown.

Objective

To measure the risk of hematologic malignant neoplasms associated with perioperative abdominopelvic CT radiation among patients who underwent appendectomy for acute appendicitis.

Design, Setting, and Participants

This nationwide population-based cohort study used the National Health Insurance Service claims database in South Korea to assess 825 820 patients who underwent appendectomy for appendicitis from January 1, 2005, to December 31, 2015, and had no underlying risk factors for cancer. Patients were divided into CT-exposed (n = 306 727) or CT-unexposed (n = 519 093) groups. The study was terminated on December 31, 2017, and data were analyzed from October 30, 2018, to September 27, 2020.

Exposures

Perioperative abdominopelvic CT examination from 7 days before to 7 days after appendectomy.

Main Outcomes and Measures

The primary outcome was the incidence rate ratio (IRR) of hematologic malignant neoplasms for both groups. The secondary outcomes were IRR of abdominopelvic organ cancers and IRR of all cancers. The lag period was 2 years for the primary outcome and 5 years for secondary outcomes. The IRRs were calculated using Poisson regression models with adjustment for age and sex.

Results

Among the study population of 825 820 patients (52.9% male; median age, 28 [interquartile range, 15-41] years), hematologic malignant neoplasms developed in 323 patients in the CT-exposed group during 1 486 518 person-years and 500 patients in the CT-unexposed group during 3 422 059 person-years. For all hematologic malignant neoplasms, the IRR for the CT-exposed vs CT-unexposed group was 1.26 (95% CI, 1.09-1.45; P = .002). In terms of individual categories of hematologic malignant neoplasms, the CT-exposed group had an elevated risk only for leukemia (IRR, 1.40 [98.75% CI, 1.04-1.87, adjusted by Bonferroni correction]; P = .005). There was no between-group difference in incidence rate of abdominopelvic organ cancers (IRR, 1.07 [95% CI, 1.00-1.15]; P = .06) and that of all cancers (IRR, 1.04 [95% CI, 0.99-1.09]; P = .14).

Conclusions and Relevance

This study controlled for reverse causation bias by defining the reasons for CT scan, and findings suggest that abdominopelvic CT radiation is associated with a higher incidence of hematologic malignant neoplasms. Efforts should be continued for judicious use of CT examinations.

Bonn call for action and the unfinished task of radiation protection of children and adolescents in low and middle-income countries: A focus on Sub-Saharan Africa

OBJECTIVES

The Bonn call for action, with the theme: "Setting the scene for the next decade," was declared over nine years ago to strengthen radiation protection in medicine. This study reviews key actions and activities related to radiation protection of children and adolescents consistent with the Bonn call for action in sub-Saharan Africa to highlight progress and identify existing gaps.

KEY FINDINGS

A lot has happened since the declaration of the Bonn call-for-action such as a follow-up conference in 2017 on achieving change in the practice of radiation protection. However, there exists a huge gap that needs to be filled in the radiation protection of children and adolescents in low and middle-income countries particularly sub-Saharan Africa, where limited resources in health compete with radiation protection demands. Some of the gaps that remain are the apparent lack of implementation of the use of referral guidelines and establishment of national and regional diagnostic reference levels for paediatric imaging among others.

CONCLUSION

Several strides have been achieved on a global scale for the Bonn call for action, ranging from the justification of medical exposures to the current drive for radiation safety culture in medical imaging. However, several unmet needs for radiation protection for children and adolescents remain such as implementation of referral guidelines for justification and paediatric diagnostic reference levels.

IMPLICATIONS FOR PRACTICE

Step up actions and close collaboration is required to strengthen the practice of paediatric radiation protection in low and middle-income countries because children account for a greater proportion of the population and are vulnerable to the negative effects of radiation like possible cancer induction.

LOCAL STUDY OF DIAGNOSTIC REFERENCE LEVELS FOR COMPUTED TOMOGRAPHY EXAMINATIONS OF ADULT PATIENTS IN İZMIR, TURKEY

PURPOSE

This study aims to develop local diagnostic reference levels (DRLs) for the most common computed tomography (CT) examinations carried out around Izmir, Turkey.

METHODS

Five common CT examinations (head, neck, chest, abdomen-pelvis (AP), chest-abdomen-pelvis (CAP)) from four different radiology centres have been included in the study. CT dose index-volume (CTDIvol) and dose length product (DLP) values were recorded for 50 patients per exam in each centre. Third quartiles of CTDIvol and DLP values were determined as DRLs and compared with international findings.

RESULTS

51.3% of the patients were male and 48.7% were female, with a mean age of 57 (between 18 and 93). DRLs for CTDIvol were recorded as 70, 16, 15, 23 and 16 for head, neck, chest, AP and CAP examinations, respectively, while the corresponding DLPs were 1385, 604, 567, 998 and 1180 mGy.cm.

CONCLUSION

Results are mostly comparable to the latest international data, except for the head examinations, which were observed to slightly exceed the DRLs established by other countries.

Technological developments of X-ray computed tomography over half a century: User's influence on protocol optimization

Since the introduction of Computed Tomography (CT), technological improvements have been impressive. At the same time, the number of adjustable acquisition and reconstruction parameters has increased substantially. Overall, these developments led to improved image quality at a reduced radiation dose. However, many parameters are interrelated and part of automated algorithms. This makes it more complicated to adjust them individually and more difficult to comprehend their influence on CT protocol adjustments. Moreover, the user's influence in adapting protocol parameters is sometimes limited by the manufacturer's policy or the user's knowledge. As a consequence, optimization can be a challenge. A literature search in Embase, Medline, Cochrane, and Web of Science was performed. The literature was reviewed with the objective to collect information regarding technological developments in CT over the past five decades and the role of the associated acquisition and reconstruction parameters in the optimization process.

Computed tomography diagnostic reference levels for adult brain, chest and abdominal examinations: A systematic review

OBJECTIVES

Radiation dose variation within and among Computed Tomography (CT) centres is commonly reported. This work systematically reviewed published articles on adult Diagnostic Reference Levels (DRLs) for the brain, chest and abdomen to determine the causes and extent of variation. A systematic literature search and review was performed in selected databases containing leading journals in radiography, radiology and medical physics using carefully defined search terms related to CT and DRLs. The quality of the included articles was determined using the Effective Public Health Practise Project tool for quantitative studies.

KEY FINDINGS

The 54 articles reviewed include: 45 studies using human data, 8 studies using phantom data, and one study with both human and phantom data. The main comparator in between studies was the dose indices used in reporting DRLs. DRL variations of up to a factor of 2 for the same procedure were noted in phantom studies, and up to a factor of 3 in human studies. Sources of variation include the type of scanner, the age of the scanner, differences in protocols, variations in patients, as well as variations in study design. Different combinations of dose indices were reported: volume computed tomography dose index (CTDIvol) and dose length product (DLP) (59%); DLP only (11%); weighted computed tomography dose index (CTDIw) and DLP (9%); CTDIvol only (7%); CTDIvol, DLP and effective dose (ED) (6%); CTDIw only (4%); CTDIvol, DLP and size specific dose estimate (SSDE) (1%) and CTDIw, CTDIvol and DLP (1%). The use of different dose indices limited dose comparison between studies.

CONCLUSION

The study noted a 2-3 fold variation in DRLs between studies for the same procedure. The causes of variation are reported and include study design, scanner technology and the use of different dose indices.

IMPLICATIONS FOR PRACTICE

There is a need for standardisation of CT DRLs in line with the International Commission on Radiological Protection recommendations to reduce dose variation and facilitate dose comparison.

A systematic review on the current status of adult diagnostic reference levels in head, chest and abdominopelvic Computed Tomography

Computed tomography (CT) is a routinely employed diagnostic tool for the detection and diagnosis of disease processes. Despite the primary focus of radiation dose reduction and improvements in CT scanners, radiation dose exposure remains an ever-increasing concern. Scanning protocol optimisation relative to body weight and scanner manufacturer still lags behind the diagnostic reference levels (DRLs) that are set on an international scale. The aim of this systematic review is to evaluate the current status of adult DRLs in head, chest and abdominopelvic CT over time on a global scale. A search was carried out in early 2019 using the Medline, PubMed, EMBASE, SCOPUS and manual databases. The reference lists of published articles were also assessed to identify further articles. The preferred reporting items for systematic reviews and meta-analyses (PRISMA) methodology was employed to evaluate articles for relevance. Articles were included if they assessed the DRL in head, chest and abdominopelvic scans. The search resulted in 6079 articles, of which 67 were included after a thorough screening process. The literature demonstrates a wide dose variation in reported head, chest and abdominopelvic dose length product (DLP) DRL, ranging from 700-1359, 330-707 and 550-1486 mGy·cm, respectively. Where reported, the volumed CT dose index (CTDI_vol) DRL in the head, chest and abdominopelvic studies ranged from 30.4-85.5, 9-15 and 12.3-31 mGy·cm, respectively. The global means were shown to be slightly lower and significantly lower than the reported values of DLP and CTDI_vol values for the American College of Radiology and European Commission, respectively. This review emphasises the need for an international standardisation for head and body DRL establishment methods, to provide a more comparable global measurement of dose variations across CT sites as well as regular monitoring of delivered radiation dose to patients.

Computed tomography radiation doses for common computed tomography examinations: a nationwide dose survey in United Arab Emirates

OBJECTIVES

Computed tomography (CT) scanning is an essential part of diagnostic and treatment plans, providing swift and accurate diagnostic images. The aim of this study is to develop diagnostic reference levels (DRLs) for the adult common CT examination in the United Arab Emirates (UAE).

METHODS

This study presents results of the survey of CT dose indices. The data were collected from 91% of the scanners registered at the Ministry of Health and Prevention (MOHAP) for five common examinations: head, chest, and abdomen-pelvis with and without CM.

RESULTS

CT dose index, dose-length product, and patient weight were analyzed; the reference dose was calculated on the 75th percentile, and an achievable dose was proposed from the median value. The results were compared with the UAE initial National Dose Report as well as the international reports. The proposed dose for CTDI_vol (mGy) and DLP (mGy cm) is as follows: head without CM 40 and 695, head with CM 48 and 820, chest 10 and 275, abdomen-pelvis without CM 14 and 810, and abdomen-pelvis with CM 20 and 1025.

CONCLUSIONS

The results show low dose variations between the MOHAP scanners. The data also revealed CTDI_vol and DLP values comparable to those in the initial NDRL report and international standards. The establishment of diagnostic reference levels will require a continuous dose monitoring system.

Radiation dose tracking in computed tomography: Red alerts and feedback. Implementing a radiation dose alert system in CT

INTRODUCTION

This study investigates instances of elevated radiation dose on a radiation tracking system to determine their aetiologies. It aimed to investigate the impact of radiographer feedback on these alerts.

METHODS

Over two six-month periods 11,298 CT examinations were assessed using DoseWatch. Red alerts (dose length products twice the median) were identified and two independent reviewers established whether alerts were true (unjustifiable) or false (justifiable). During the second time period radiographers used a feedback tool to state the cause of the alert. A Chi-Square test was used to assess whether red alert incidence decreased following the implementation of radiographer feedback.

RESULTS

There were 206 and 357 alerts during the first and second time periods, respectively. These occurred commonly with CT pulmonary angiography, brain, and body examinations. Procedural documentation errors and patient size accounted for 57% and 43% of false alerts, respectively. Radiographer feedback was provided for 17% of studies; this was not associated with a significant change in the number of alerts, but the number of true alerts declined (from 7 to 3) (χ2 = 4.14; p = 0.04).

CONCLUSION

Procedural documentation errors as well as patient-related factors are associated with false alerts in DoseWatch. Implementation of a radiographer feedback tool reduced true alerts.

IMPLICATIONS FOR PRACTICE

The implementation of a radiographer feedback tool reduced the rate of true dose alerts. Low uptake with dose alert systems is an issue; the workflow needs to be considered to address this.

DOSE BENCHMARKS FOR PAEDIATRIC HEAD COMPUTED TOMOGRAPHY EXAMINATION IN NIGERIA

Diagnostic reference levels (DRLs) provide benchmarks for dose optimisation. We aimed to propose DRLs for paediatric head computed tomography (CT) in Nigeria and assess if facilities adapt protocols to age-specific standardisations. Volume CT dose index (CTDIvol) and dose-length-product (DLP) of at least 20 paediatric patients per age group were extracted from 11 facilities and used to propose DRLs. Kruskal-Wallis and Median tests were used to assess the contribution of age to paediatric dose variations. CTDIvol (mGy)/DLP (mGy.cm) ranged 16-31/100-1603 (newborn), 10-92/75-4072 (1-y-old), 10-81/169-2603 (5-y-olds) and 14-86/119-3945 (≥10-y-olds). The 75th percentile CTDIvol/DLP values were 27/1040, 37/988, 48/1493 and 54/1824 for newborn, 1-y, 5-y, ≥10-y-olds, respectively. Age accounted for 18.4 and 5.3% variations in median CTDIvol and DLP, respectively. Paediatric head CT doses in Nigeria are higher than reported internationally, suggesting a need for dose optimisation interventions.