Establishment Of Diagnostic Reference Levels Research Articles

An analysis of patient dose received during cone-beam computed tomography in relation to scan settings and imaging indications as seen in a dental institution in order to establish institutional diagnostic reference levels.

To investigate the dose-area product (DAP) of cone-beam computed tomography (CBCT) examinations for different scan settings and imaging indications, and to establish institutional diagnostic reference levels (DRLs) for dose optimisation. A retrospective analysis of the DAP values of 3568 CBCT examinations taken from two different devices at the Prince Philip Dental Hospital, Hong Kong between 2016 and 2021 was performed. Patient- (age, gender, and imaging indication) and imaging-related (CBCT device, field-of-view (FOV), and voxel size) were correlated with the DAPs. The indication-oriented third-quartile DAP values were compared with DRLs from the UK, Finland, and Switzerland. The obtained third-quartile DAPs lower than the national DRLs and those for which no national DRLs have been proposed were used to establish institutional DRLs. In the investigated CBCTs, the DAP value for large FOV scans was significantly lower than medium/small FOVs. CBCTs with a small voxel size exhibited a significantly higher DAP than those with a medium/large voxel size. CBCTs for endodontic, periodontal, orthodontic, or orthognathic evaluation exhibited a significantly higher DAP than other indications. Twelve indication-oriented institutional DRLs were established and five of them were lower than the national DRLs: third molars (229 mGy×cm2), jaw cysts/tumours (410 mGy×cm2), maxillary sinus pathology (520 mGy×cm2), developing dentition (164 mGy×cm2), and periapical lesions (564 mGy×cm2). CBCT examinations for endodontic, periodontal, orthodontic, or orthognathic evaluation may deliver a higher radiation dose to the patient than other imaging tasks. A periodic review of the patient dose from CBCT imaging and establishment of institutional DRLs for specific clinical settings are needed for monitoring patient dose and to optimise indication-oriented scanning protocols.

First local diagnostic reference levels for fluoroscopically guided cardiac procedures in adult patients in Chile

The goal of this study was to generate the first values of local diagnostic reference levels for a range of fluoroscopically guided cardiac diagnostic and therapeutic procedures in adult patients in Chile and to compare radiation dose levels with others presented in the literature. The dosimetric data collection period was conducted over the whole of 2020. The local diagnostic reference levels were calculated as the 75th percentile of patient dose data distributions for kerma area-product values. The sample of collected clinical procedures (480) was divided into diagnostic and therapeutic procedures. The kerma area-product differences found between diagnostic and therapeutic procedures were statistically significant. The local diagnostic reference levels were 81.6 Gy cm2 and 166.9 Gycm2 for fluoroscopically guided cardiac diagnostic and therapeutic procedures, respectively. A comparison of our results with results found in the literature for the last 10 years, showed that there are no published papers for hospitals in Latin America and the Caribbean. It becomes urgent to be able to carry out more research of this type, given that the health reality between countries on different continents is very different. While in some the establishment of diagnostic reference levels is a legal obligation, in others it is a matter of good or bad will.

Comparison of Radiation Dose in CT Examinations At PIMS with European Commission Reference Doses

OBJECTIVE - The purpose of this study was to assess the radiation dose levels from common computed tomography (CT) examinations performed in Radiology Department of Pakistan Institute of Medical Sciences (PIMS), and evaluate these according to diagnostic reference levels (DRLs) proposed by European Commission (EC) guidelines, and thus contributing towards the establishment of local and national DRLs. To the best of our knowledge, this is the first study of its kind to explore radiation doses from CT examinations in Pakistan.
 STUDY DESIGN - This was a quantitative study conducted at PIMS, Islamabad, spanning a duration of eight weeks. Scan parameters and dose profile data of 1506 adults undergoing examinations of head, neck, chest and abdomen-pelvis regions, comprising of single- and multi-phase, contrast-enhanced and unenhanced studies. Dose indicators utilized by EC guidelines for DRLs include volume CT dose index (CTDIvol) and Dose Length Product (DLP) for single slice and complete examination radiation doses, respectively.
 METHOD - Values of CTDIvol, DLP and scan lengths were extracted from the CT operators console. Other control variables included gender, contrast enhancement and phasicity of study. IBM SPSS package was used to obtain descriptive statistics such as mean and quartiles.
 RESULTS - DRLs calculated as 75th percentile of CTDIvol, DLP for various anatomical regions are by and far comparable to European DRLs.
 CONCLUSION – This study describes institutional diagnostic reference levels for common CT exams in Islamabad and provides benchmark values for future reference. Our DRL values are mostly comparable to European and international DRLs. Similar, albeit large scale, surveys are recommended for establishment of local and national DRLs, eventually contributing towards development of regional DRLs.
 KEYWORDS: CTDIvol, DLP, Diagnostic Reference Levels, Computed Tomography, Radiation Monitoring, Scan length

Establishment of diagnostic reference level for computed tomography of head pediatrics in Morocco: A pilot study

Pediatric patients are well documented to be at higher risk of developing radiation-induced cancer than the average adult. This pilot study aims to estimate the radiation doses to pediatric patients during head Computed Tomography (CT), in order to establish local Diagnostic Reference Level (DRL).Data from 300 pediatric head CT examinations from 6 public hospitals were analyzed. The age group concerned is 5–10 years. The CT facilities were 64, 16, 4 and dual slice type. CT data included scanner acquisition parameters, the number of series, use of the contrast medium, rotation time, slice thickness, as well as the displayed CT Dose Index (CTDIvol) and the Dose Length Product (DLP). The effective dose and DRL were evaluated using the formalism and conversion factor of the International Commission on Radiological Protection (ICRP).The overall mean CT dose per procedure from different facilities was 44,97 mGy, 883,67 mGy.cm and 2,81 mSv for CTDIvol, DLP and effective dose, respectively. The mean third quartile dose per head CT procedure from all facilities was 40,94 mGy and 969,90 mGy.cm cm for CTDI and DLP, in that order. These results proved that pediatric patients are exposed to unnecessary doses of radiation during CT examination in public healthcare institution of Morocco.The DRL obtained was slightly higher than those established in some countries. Pediatric radiation dose per procedure indicated a wide variation between various hospitals and even in the same hospital for different patients. This pilot study showed the need for practices unification and radiation doses optimization during CT scan acquisition for pediatric patients in radiology departments.

Single- and Dual-Source CT Myelography: Comparison of Radiation Exposure and Establishment of Diagnostic Reference Levels.

CT myelography (CTM) is a diagnostic technique for the evaluation of various spinal pathologies, and plays an important role in diagnosis of different diseases such as spontaneous intracranial hypotension and postoperative cerebrospinal fluid leaks. The aims of this study were to examine radiation exposure, establish diagnostic reference levels (DRLs) and compare radiation doses of single- and dual-source examinations and different CTM protocols. In this retrospective study, 183 CTMs comprising 155 single-source and 28 dual-source examinations, performed between May 2015 and December 2020, were analyzed. Dose data included 31 whole spine (A), 23 cervical (B), 10 thoracic (C), and 119 lumbar (D) CTMs. Radiation exposure was reported for volume-weighted CT dose index (CTDIvol) and dose-length product (DLP). Radiation doses for CTDIvol and DLP were distributed as follows (median, IQR): A: 7.44 mGy (6.01–11.17 mGy)/509.7 mGy·cm (382.4–682.9 mGy·cm), B: 9.31 mGy (7.20–14.64 mGy)/214.5 mGy·cm (153.7–308.2 mGy·cm), C: 6.80 mGy (6.14–8.26 mGy)/365.4 mGy·cm (222.8–432.4 mGy·cm), D: 11.02 mGy (7.97–14.89 mGy)/308.0 mGy·cm (224.7–413.7 mGy·cm). Local DRLs could be depicted as follows (CTDIvol/DLP): A: 11 mGy/683 mGy·cm, B: 15 mGy/308 mGy·cm, C: 8 mGy/432 mGy·cm, D: 15 mGy/414 mGy·cm. High image quality was achieved for all anatomical regions. Basically, radiation exposure of CTM differs according to anatomical location.

ESTIMATION OF RADIATION RISK AND ESTABLISHMENT OF DIAGNOSTIC REFERENCE LEVELS FOR PATIENTS UNDERGOING COMPUTED TOMOGRAPHY CHEST-ABDOMEN-PELVIC EXAMINATIONS IN SUDAN.

Establishment of diagnostic reference levels (DRLs) is an essential radiation optimization tool used to indicate optimum practice and radiation protection. This study aimed to report the current computed tomography (CT) of the chest-abdomen-pelvis radiation practice in Sudan as a part of the DRL establishment effort and dose optimization. CT radiation doses were collected from 530 patients of age ranging between 28 and 85y and body weight ranging between 65 and 120kg. DRLs were calculated based on the 75th percentile of dose length product (DLP) and CT dose index volume (CTDIvol). Effective and organ doses were calculated using the National Cancer Institute dosimetry system for the CT programme. The proposed DRLs are CTDIvol, 6mGy, and DLP, 970mGy.cm, and an effective dose of 9.9mSv. Organ dose estimation showed that the thyroid received the highest dose during the scan.

Radiation exposure and establishment of diagnostic reference levels of whole-body low-dose CT for the assessment of multiple myeloma with second- and third-generation dual-source CT.

In the assessment of diseases causing skeletal lesions such as multiple myeloma (MM), whole-body low-dose computed tomography (WBLDCT) is a sensitive diagnostic imaging modality, which has the potential to replace the conventional radiographic survey. To optimize radiation protection and examine radiation exposure, and effective and organ doses of WBLDCT using different modern dual-source CT (DSCT) devices, and to establish local diagnostic reference levels (DRL). In this retrospective study, 281 WBLDCT scans of 232 patients performed between January 2017 and April 2020 either on a second- (A) or third-generation (B) DSCT device could be included. Radiation exposure indices and organ and effective doses were calculated using a commercially available automated dose-tracking software based on Monte-Carlo simulation techniques. The radiation exposure indices and effective doses were distributed as follows (median, interquartile range): (A) second-generation DSCT: volume-weighted CT dose index (CTDIvol) 1.78 mGy (1.47-2.17 mGy); dose length product (DLP) 282.8 mGy·cm (224.6-319.4 mGy·cm), effective dose (ED) 1.87 mSv (1.61-2.17 mSv) and (B) third-generation DSCT: CTDIvol 0.56 mGy (0.47-0.67 mGy), DLP 92.0 mGy·cm (73.7-107.6 mGy·cm), ED 0.61 mSv (0.52-0.69 mSv). Radiation exposure indices and effective and organ doses were significantly lower with third-generation DSCT (P < 0.001). Local DRLs could be set for CTDIvol at 0.75 mGy and DLP at 120 mGy·cm. Third-generation DSCT requires significantly lower radiation dose for WBLDCT than second-generation DSCT and has an effective dose below reported doses for radiographic skeletal surveys. To ensure radiation protection, DRLs regarding WBLDCT are required, where our locally determined values may help as benchmarks.

Establishment of Diagnostic Reference Levels for Computed Tomography Scanning in Hamadan.

Background: New advancements have increased the capabilities of computed tomography as a sectional medical imaging modality. An important note is assessing absorbed dose to patients and minimizing it when performing computed tomography examinations. One approach to control dose is to establish diagnostic reference levels.Objective: This study aimed to investigate diagnostic reference levels of computed tomography in Hamadan.Material and Methods: This work was conducted as an experimental study. Computed tomography dose index (CTDI) was measured using a Piranha quality control kit, head and body CTDI phantoms for brain, lung, abdomen-pelvic and coronary CT angiography examinations. Volume Computed Tomography Dose Index (CTDIvol) was calculated from obtained data and 3rd quartile of that was determined as diagnostic reference levels.Results: Diagnostic reference levels (DRLs) in terms of CTDIvol for brain, lung, abdomen-pelvic and coronary CT angiography were 50/25, 6/73, 22/01 and 32/06 mGy respectively in Hamadan. Difference between displayed CTDIvol and measured CTDIvol is not significance for all examinations (p>0.05). Conclusion: DRLs depend on to many dose affecting parameters in CT. DRL for brain CT is greater than other scan regions. Application of DRLs which resulted from this study can help to optimize radiation dose to the patients while maintaining acceptable diagnostic images quality.

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

ObjectivesComputed 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).MethodsThis 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.ResultsCT 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 CTDIvol (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.ConclusionsThe results show low dose variations between the MOHAP scanners. The data also revealed CTDIvol 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.

Establishment of Diagnostic Reference Levels and Estimation of Effective Dose from Computed Tomography Head Scans at a Tertiary Hospital in South Africa

Introduction: Head scans are the most frequently performed computed tomography (CT) examinations worldwide. However, there is growing concern over the probability of increased cancer risks among the exposed populations. Diagnostic reference levels (DRLs) identify radiation dose that is not commensurate with clinical objectives. The aim of this study was to establish DRLs for CT head procedures and estimate effective dose (ED). Material and Methods: The dose absorbed by the head slice of a Rando Alderson phantom was measured using calibrated lithium fluoride thermoluminescent dosimeters (TLDs) exposed to a CT scanner operated on clinical parameters. The measurements were done at the periphery and center of the slice, and repeated twice with a new set of TLDs. The radiation dose absorbed by the TLDs was read using a Harshaw TLD reader, Model 5500. The measured doses were used to calculate the weighted CT dose index (CTDIw), CT dose index volume (CTDIv), and dose length product (DLP). Finally, the ED was calculated using the formula; ED = k × DLP, where k was considered as 0.0021. Results: The mean absorbed dose was 30.9 mGy, while the established CTDIv and DLP values for the head protocol were 40 mGy and 990 mGy.cm, respectively. Additionally, the ED was calculated as 2.1 mSv. These values compared well with some international values. Conclusion: According to the results of the present study, the established CTDIv, DLP, and ED for head scan were well-compared with some international values, except in the cases using different scan lengths and scanner algorithms.

An Investigation into the Infrastructure and Management of Computerized Tomography Units in Ghana

IntroductionIn Ghana, there is a need to document computed tomography (CT) infrastructure and management systems for the development of interventions to promote CT practices while ensuring patient protection through the establishment of diagnostic reference levels and improved dose management systems. MethodsA quantitative inquiry using a descriptive, cross-sectional approach was used to collect data, using a semistructured questionnaire related to CT infrastructure and management from the technical heads responsible for CT scanners. Data collected included the scanner characteristics, basic management system and organizational arrangements, number of attending practitioners, clinical indications for CT examinations, and the operation of CT facilities in Ghana. ResultsOf the 35 CT scanners installed across the country, 31 were involved in the study. The majority (29%) were Toshiba models. Equipment slices ranged from 1 to 640, of which 45.2% were 16-slice scanners. Many (n = 28, 90.3%) were functioning, and most were installed in the capital city, Accra. The equipment mean age was 7.3 ± 4.4 years, and 25.6% were 10 or more years old. There were 107 operating radiographers, 60 reporting radiologists, and 10 medical physicists employed across the facilities. A total of 204,760 CT examinations were performed yearly (6.8 CT procedures per 1000 people in Ghana). Head CT procedures were the most common, and suspicion of cerebrovascular accident or stroke (32.8%) was the most common indication. Some basic quality management system and policy driving CT infrastructure in Ghana were lacking. ConclusionThe results have provided essential information on the status of CT infrastructure and management systems for policy development and planning in CT facilities in Ghana. This study provides those interested in CT services, jobs, or medical equipment investment in Ghana the information needed to make appropriate decisions.

Towards establishment of diagnostic reference levels based on clinical indication in the state of Qatar

ObjectivesThe objectives of this study were to: 1) evaluate patient radiation exposure in CT and 2) establish CT Diagnostic Reference Levels (DRL)s based on clinical indication (CI) in Qatar. Materials and MethodsPatient data for 13 CIs were collected using specially designed collection forms from the dose management software (DMS) of Hamad Medical Corporation (HMC), the main Qatar healthcare provider. The methodology described in the International Commission on Radiological Protection (ICRP) Report 135 was followed to establish national clinical DRLs in terms of Volumetric Computed Tomography Dose Index (CTDIvol) and total Dose Length Product (DLPt). Effective dose (Ef) was estimated by DMS using DLPt and appropriate conversion factors and was analyzed for comparison purposes. ResultsData were retrospectively collected for 896 adult patients undergoing CT examinations in 4 hospitals and 7 CT scanners. CT for Diffuse infiltrative lung disease imparted the lowest radiation in terms of CTDIvol (5 mGy), DLPt (181 mGy.cm) and Ef (3.6 mSv). Total body CT for severe trauma imparted the highest DLPt (3137 mGy.cm) and Ef (38.6 mSv) of all CIs with a CTDIvol of 15 mGy. Rounded Third quartile CTDIvol and DLPt values were defined as the Qatar CT clinical DRLs. Comparison was limited due to sparse international literature. When this was possible data were lower or comparable with other studies. ConclusionsThis is the first study reporting national clinical DRLs in Asia and second one internationally after UK. For accurate comparison between studies, systemized CI nomenclature must be followed by researchers.

Establishment of Diagnostic Reference Levels for Radiography in 10-year-old Pediatric Patients in Republic of Korea

The diagnostic reference levels (DRLs) for a 10-year-old patient were established for the most common types of general radiography in this study, using a glass dosimeter and a phantom corresponding to the international standards. The DRLs are set by measuring the entrance surface doses (ESD) at 211 medical institutions. The ESD of the skull posterior-anterior (PA) projection is between 0.11 and 5.59 mGy, with the average dose at 1.03 mGy, and the third quartile value at 1.17 mGy. The ESD of the skull lateral (LAT) projection is between 0.08 and 5.20 mGy, with the average dose at 0.78 mGy, and the third quartile value at 0.96 mGy. The ESD of the chest PA projection is between 0.01 and 1.38 mGy, with the average dose at 0.18 mGy, and the third quartile value at 0.20 mGy. The ESD of the chest LAT projection is between 0.04 and 3.36 mGy, with the average dose at 0.42 mGy, and the third quartile value at 0.46 mGy. The ESD of the abdomen AP projection is between 0.09 and 4.64 mGy, with the average dose at 0.85 mGy, and the third quartile value at 1.13 mGy. The ESD of the pelvis AP projection is between 0.1 and 5.26 mGy, with the average dose at 0.85 mGy, and the third quartile value at 1.06 mGy. Based on third quartile values and through clinical expert consultation, the DRLs for 10-year-olds in Korea were established at 1.1 mGy for skull PA, 0.9 mGy for skull LAT, 0.2 mGy for chest PA, 0.4 mGy for chest LAT, 1.1 mGy for abdomen AP, and 1.0 mGy for pelvis AP.

Development of size-specific institutional diagnostic reference levels for computed tomography protocols in neck imaging

Purpose: To develop size-specific institutional diagnostic reference levels (DRLs) for computed tomography (CT) protocols used in neck CT imaging (cervical spine CT, cervical CT angiography (CTA) and cervical staging CT) and to compare institutional to national DRLs. Materials and methods: Cervical CT examinations (spine, n = 609; CTA, n = 505 and staging CT, n = 184) performed between 01/2016 and 06/2017 were included in this retrospective study. For each region and examination, the volumetric CT dose index (CTDIvol) and dose-length product (DLP) were determined and binned into size bins according to patient water-equivalent diameter (dw). Linear regression analysis was performed to calculate size-specific institutional DRLs for CTDIvol and DLP, applying the 75th percentile as the upper limit for institutional DRLs. The mean institutional CTDIvol and DLP were compared to national DRLs (CTDIvol 20 mGy for cervical spine CT (DLP 300 mGycm) and cervical CTA (DLP 600 mGycm), and CTDIvol 15 mGy for cervical staging CT (DLP 330 mGycm)). Results: The mean CTDIvol and DLP (±standard deviation) were 15.2 ± 4.1 mGy and 181.5 ± 88.3 mGycm for cervical spine CT; 8.1 ± 4.3 mGy and 280.2 ± 164.3 mGycm for cervical CTA; 8.6 ± 1.9 mGy and 162.8 ± 85.0 mGycm for cervical staging CT. For all CT protocols, there was a linear increase in CTDIvol and DLP with increasing dw. For the CTDIvol, size-specific institutional DRLs increased with dw from 14 to 29 mGy for cervical spine CT, from 5 to 17 mGy for cervical CTA and from 8 to 13 mGy for cervical staging CT. For the DLP, size-specific institutional DRLs increased with dw from 130 to 510 mGycm for cervical spine CT, from 140 to 640 mGycm for cervical CTA and from 140 to 320 mGycm for cervical staging CT. Institutional DRLs were lower than national DRLs by 81% and 67% for cervical spine CT (dw = 17.8 cm), 43% and 51% for cervical CTA (dw = 19.5 cm) and 59% and 53% for cervical staging CT (dw = 18.8 cm) for CTDIvol and DLP, respectively. Conclusion: Size-specific institutional DRLs were generated for neck CT examinations. The mean institutional CTDIvol and DLP values were well below national DRLs.

Establishment of diagnostic reference levels in cardiac computed tomography.

The aim of this study was to determine diagnostic reference levels (DRLs) for cardiac computed tomography (CCT) in Jordan. Volume computed tomography dose index (CTDIvol) and dose–length product (DLP) were collected from 228 CCTs performed at seven Jordanian hospitals specialized in cardiac CT. DRLs for cardiac CT were defined at the 75th percentile of CTDIvol and DLP. CTDIvol and DLP were collected from 30 successive cardiac CT in each center except for one center (18 scans). The 75th percentile of the CTDIvol and the DLP of the centers calculated from mixed retrospective and prospective gated modes were 47.74 milligray (mGy) and 1035 mGy/cm, respectively. This study demonstrated wide dose variations among the surveyed hospitals for cardiac CT scans; there was a 5.1‐fold difference between the highest and lowest median DLP with a range of 223.2–1146.7 mGy/cm. Differences were associated with variations in the mAs and kVp. This study confirmed large variability in CTDIvol and DLP for cardiac CT scans; variation was associated with acquisition protocols and highlights the need for dose optimization. DRLs are proposed for CCT; there remains substantial potential for optimization of cardiac CT examinations for adults in Jordan.

Establishment of diagnostic reference levels arising from common CT examinations in Semnan County, Iran

Abstract Objective: The literature has approved that the use of the concept of diagnostic reference level (DRL) as a part of an optimization process could help to reduce patient doses in diagnostic radiology comprising the Computed Tomography (CT) examinations. There are four public/governmental CT centers in the province (Semnan, Iran) and, to our knowledge, after about 12 years since the launch of the first CT scanner in the province there is no dosimetry information on those CT scanners. The aim of this study was to evaluate CT dose indices with the aim of the establishment of the DRL for head, chest, cervical spine, and abdomen-pelvis examinations. Methods: Scan parameters of 381 patients were collected during two months from 4 CT scanners. The CT dose index (CTDI) was measured using a calibrated ionization chamber on two cylindrical poly methyl methacrylate (PMMA) phantoms. For each sequences, weighted CTDI (CTDIw), volumetric CTDI (CTDIv) and dose length product (DLP) were calculated. The 75th percentile was proposed as the criterion for DRL values. Results: Proposed DRL (CTDIw, CTDIv, DLP) for the head, chest, cervical spine, and abdomen-pelvis were (46.1 mGy, 46.1 mGy, 723 mGy × cm), (13.8 mGy, 12.0 mGy, 377 mGy × cm), (40.0 mGy, 40.0 mGy, 572 mGy × cm) and (14.9 mGy, 12.1 mGy, 524 mGy × cm), respectively. Conclusion: Comparison with the others results from the other countries indicates that the head, chest and abdomen-pelvis scans in our region are lower or in the range of the other studies investigated in terms of dose. In the case of cervical spine scanning it’s necessary to review and regulate scan protocols to reach acceptable dose levels.

European Society of Paediatric Radiology Computed Tomography and Dose Task Force: European guidelines on diagnostic reference levels for paediatric imaging.

The recent European Council Directive 2013/59/EURATOM requires the establishment of diagnostic reference levels (DRLs) to optimise radiation dose in diagnostic and interventional radiology procedures. At the time this directive was enacted, just a few European countries had already set paediatric DRLs and many of these were outdated. For this reason, the European Commission launched a project addressing European Guidelines on Diagnostic Reference Levels for Paediatric Imaging that was awarded to a consortium led by the European Society of Radiology with the collaboration of the European Society of Paediatric Radiology and other European stakeholders involved in the radiation protection of children. The main aims of this project were to establish European DRLs to be used by countries without their own national paediatric DRLs and to provide a consistent method to establish new DRLs in the future. These European guidelines have been very recently endorsed by the European Commission and published in issue N° 185 of the Radiation Protection series. The purpose of this article is to introduce these guidelines to the wide community of paediatric radiologists.

Coronary CT angiography radiation dose trends: A 10-year analysis to develop institutional diagnostic reference levels

Purpose: To develop institutional diagnostic reference levels (IDRL) for coronary CT angiography (CCTA) according to patient size by analyzing radiation dose changes over the past 10 years.Materials and methods: This IRB approved retrospective investigation analyzed radiation dose data from CCTA between 2007 and 2016 at our institution. Annual trends in radiation dose were described for each scanner type and scanning mode. Radiation levels were analyzed for normorhythmic patients, patients with prior coronary artery bypass grafting (CABG), arrhythmia, and according to patient size and tube voltage. Median, and quartile values for volume CT dose index (CTDIvol), dose-length product (DLP), and size-specific dose estimate (SSDE) were calculated. Wilcoxon rank-sum test and Kruskal Wallis test were performed to assess the significance of quantitative data.Results: 35,375 examinations from 33,317 patients (median age, 58 [50–66] years; male patients, 21,087 [58.7%]) were analyzed. CTDIvol, DLP, and SSDE significantly decreased by 9.0%, 30.8%, and 40.1% (all P < 0.05) for all examinations, respectively. All radiation dose metrics progressively decreased across scanning modes (especially retrospectively ECG-gated spiral and prospectively ECG-triggered high-pitch spiral acquisition mode), but did not significantly change across scanners in the last 6 years. CTDIvol and DLP increased with patient size when water-equivalent diameters were >19 cm for normorhythmic and CABG patients. In arrhythmic patients, CTDIvol increased progressively with water-equivalent diameters across all groups.Conclusion: CCTA radiation dose has progressively decreased in the past decade except in patients with prior CABG and arrhythmia. Size-specific IDRLs may optimize radiation utilization in these patients going forward.

P040] Variability of mammographic exam doses as a result of positioning and technique

Purpose Automatic collection of dosimetric data from PACS (Picture Archiving and Communication System) allows comparisons of exam doses and establishment of diagnostic reference levels (DRLs) based on large datasets. In an oncology institute, dosimetric data pertaining to mammography will include breasts previously submitted to surgery and radiotherapy, in addition to data from untreated breasts. It seems timely to compare dosimetric data for treated and untreated breasts, to determine if the two should be considered separately. The aim of this work is to establish the baseline of normal variation attributable to positioning and technique in mammography, for comparison with the variation between treated and untreated breasts. Methods 10 patients were randomly selected among those who had multiple mammographic exams archived in PACS and no previous history of surgery or radiotherapy. These patients were submitted to between 4 and 9 exams, performed in the same mammographic unit (GE Senograph DS), in standard automatic exposure mode, over a period of 8 years. The anonymized images were downloaded from PACS, and a script was written in Python to extract the necessary information: compression force, compressed breast thickness, entrance surface air kerma (ESAK), mean glandular dose (MGD), area and maximum perpendicular width of the imaged region. The area and maximum width were obtained using thresholding, while the other parameters were extracted from the DICOM header. Results The most variable parameter proved to be the compression force, which for the same patient (same view, same side) had typical variability between exams around 19–23% of the mean value, reaching more than 30% in some patients. The maximum width and the area of the imaged region had the least variability (3% and 4% respectively). Visual comparison of the contours for different years confirms the good reproducibility of positioning, despite small translational variations. Variability of MGD and ESAK was 6–7% and 9–10% respectively, for repeated views of the same untreated breast. Conclusions Variability of exam doses with positioning and technique for the same mammographic unit was found to be small, despite large variations in the compression force. This is probably related to the remarkably consistent positioning.

CT examination effective doses in Saudi Arabia

Patient effective doses and the associated radiation risks arising from particular computed tomography (CT) imaging procedures are assessed. The objectives of this research are to measure radiation doses for patients and to quantify the radiogenic risks from CT brain and chest procedures. Patient data were collected from five calibrated CT modality machines in Saudi Arabia. The results are from a study of a total of 60 patients examined during CT procedures using the calibrated CT units. For CT brain and chest, the mean patient effective doses were 1.9 mSv (with a range of 0.6–2.5 mSv) and 7.4 mSv (with a range of 0.5–34.8 mSv) respectively. The radiogenic risk to patients ranged from between 10−5 and 10−4 per procedure. With 65% of the CT procedure cases diagnosed as normal, this prompts re-evaluation of the referral criteria. The establishment of diagnostic reference levels (DRL) and implementation of radiation dose optimisation measures would further help reduce doses to optimal values.