Setting up a national diagnostic reference level for computed tomography for the public sector in Costa Rica: first step.

Establishment of local diagnostic reference levels for adult chest CT examinations at a South African tertiary hospital in Gauteng province, South Africa.

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.

Diagnostic reference levels (DRLs) are an important metric in identifying abnormally high radiation doses in diagnostic examinations. National DRLs for CT colonography do not currently exist in South Africa, but there are efforts to collect data for a national DRL project. This study investigated radiation doses for CT colonography in adult patients at a large tertiary hospital in South Africa with the aim of setting local DRLs. Patient data from two CT scanners (Philips Ingenuity and Siemens Somatom go.Top) in the period March 2020 - March 2023 were obtained from the hospital's picture archiving and communication system (PACS) (n = 115). Analysis involved determining the median computed tomography dose index-volume (CTDIvol) and dose-length product (DLP) values. The findings were compared with DRLs established internationally. Ingenuity median CTDIvol was 20 mGy and DLP was 2169 mGy*cm; Somatom median CTDIvol was 6 mGy and DLP was 557 mGy*cm. Ingenuity exceeded the United Kingdom's (UK) recommended DRLs by 82% and 214%, respectively. Somatom median CTDIvol and DLP were 45% and 19% lower than UK NDRLs. Somatom's tin filter and other dose reduction features provided significant dose reduction. These data were used to set DRLs for CT colonography at the hospital; CTDIvol: 6 mGy and DLP: 557 mGy*cm. In addition to informing radiation protection practices at the level of the institution, the established local DRLs contribute towards implementing regional and national DRLs.

Rationale and objectivesThis study aimed to compare the volume computed tomography dose index (CTDIvol), dose length product (DLP), and size-specific dose estimate (SSDE), with the China and updated 2017 American College of Radiology (ACR) diagnostic reference levels (DRLs) in chest CT examinations of adults based on the water-equivalent diameter (Dw).Materials and methodsAll chest CT examinations conducted without contrast administration from January 2020 to July 2020 were retrospectively included in this study. The Dw and SSDE of all examinations were calculated automatically by “teamplay”. The CTDIvol and DLP were displayed on the DICOM-structured dose report in the console based on a 32cm phantom.The differences in patient CTDIvol, DLP, and SSDE values between groups were examined by the one-way ANOVA. The differences in patient CTDIvol, DLP, and SSDE values between the updated 2017 ACR and the China DRLs were examined with one sample t-tests.ResultsIn total 14666 chest examinations were conducted in our study. Patients were divided into four groups based on Dw:270 (1.84%) in 15–20 cm group, 10287 (70.14%) in the 21–25 cm group, 4097 (27.94%) in the 26–30 cm group, and 12 (0.08%) patients had sizes larger than 30 cm. CTDIvol, DLP, and SSDE increased as a function of Dw (p<0.05). CTDIvol was smaller than SSDE among groups (p<0.05). The mean CTDIvol and DLP values were lower than the 25th, 50th, and 75th percentile of the China DRLs (p <0.05). The CTDIvol, DLP, and SSDE were lower than the 50th and 75th percentiles of the updated 2017 ACR DRLs (p <0.05) among groups.ConclusionsSSDE takes into account the influence of the scanning parameters, patient size, and X-ray attenuation on the radiation dose, which can give a more realistic estimate of radiation exposure dose for patients undergoing CT examinations. Establishing hospital’s own DRL according to CTDIvol and SSDE is very important even though the radiation dose is lower than the national DRLs.

We aimed to obtain typical values for head, neck, chest, and abdominal computed tomography (CT) examinations from routine patients in 2018, and to review our data with national and international diagnostic reference levels (DRLs). Single-phase head, neck, chest, and abdominal CT scans of adults performed in 64-slice CT in 2018 were included in this study. Radiation dose parameters of CT scans were obtained from the picture archiving and communication system of our hospital. Volumetric CT dose index (CTDIvol) and dose length product (DLP) values were recorded. Effective dose (ED) and scan length was calculated. A 16 cm diameter phantom is referenced for head CT, and 32 cm diameter phantom is referenced for neck, chest, and abdominal CT. Descriptive statistics of the variables were given according to the normality testing. Median CTDIvol value was 53 mGy for the head, 13.1 mGy for the neck, 8.3 mGy for the chest, and 8.6 mGy for the abdomen. Median DLP value was 988 mGy.cm for the head, 299 mGy.cm for the neck, 314 mGy.cm for the chest, and 457 mGy.cm for the abdomen. Median ED value was 2.07 mSv for the head, 1.76 mSv for the neck, 4.4 mSv for the chest, and 6.8 mSv for the abdomen. Considering national DRLs, median CTDIvol values of head, chest, and abdomen were lower, whereas median DLP and ED values of head and chest were higher. For the abdomen, the median DLP and ED values were lower. Overall radiation dose parameters obtained in this study points out the need for optimization of head CT examinations in our institution.

To implement automated CT dose data monitoring using the DICOM-Structured Report (DICOM-SR) in order to monitor dose-related CT data in regard to national diagnostic reference levels (DRLs). We used a novel in-house co-developed software tool based on the DICOM-SR to automatically monitor dose-related data from CT examinations. The DICOM-SR for each CT examination performed between 09/2011 and 03/2015 was automatically anonymized and sent from the CT scanners to a cloud server. Data was automatically analyzed in accordance with body region, patient age and corresponding DRL for volumetric computed tomography dose index (CTDIvol) and dose length product (DLP). Data of 36,523 examinations (131,527 scan series) performed on three different CT scanners and one PET/CT were analyzed. The overall mean CTDIvol and DLP were 51.3% and 52.8% of the national DRLs, respectively. CTDIvol and DLP reached 43.8% and 43.1% for abdominal CT (n=10,590), 66.6% and 69.6% for cranial CT (n=16,098) and 37.8% and 44.0% for chest CT (n=10,387) of the compared national DRLs, respectively. Overall, the CTDIvol exceeded national DRLs in 1.9% of the examinations, while the DLP exceeded national DRLs in 2.9% of the examinations. Between different CT protocols of the same body region, radiation exposure varied up to 50% of the DRLs. The implemented cloud-based CT dose monitoring based on the DICOM-SR enables automated benchmarking in regard to national DRLs. Overall the local dose exposure from CT reached approximately 50% of these DRLs indicating that DRL actualization as well as protocol-specific DRLs are desirable. The cloud-based approach enables multi-center dose monitoring and offers great potential to further optimize radiation exposure in radiological departments. • The newly developed software based on the DICOM-Structured Report enables large-scale cloud-based CT dose monitoring • The implemented software solution enables automated benchmarking in regard to national DRLs • The local radiation exposure from CT reached approximately 50 % of the national DRLs • The cloud-based approach offers great potential for multi-center dose analysis.

Background: Computed Tomography (CT) imaging is widely recognised for its high capability in assessing multiple organs. However, concerns about patient radiation exposure, particularly in children, pose significant challenges. Objective: This study aimed to establish diagnostic reference levels (DRLs) for paediatric patients in the most common CT examinations to monitor and better control radiation doses. Methods: Dosimetry records from 5956 patients' scans for the four most common CT imaging examinations-Head, Chest, Abdomen Pelvis (AP), and Chest Abdomen Pelvis (CAP)-were considered. The CT dosimetric quantities (CT dose-index volume (CTDIvol) and dose-length product (DLP)), along with patient demographics (age and weight), were collected from radiology data storage systems. DRLs for CTDIvol and DLP were determined for each imaging examination, stratified by patient age and weight groups, in accordance with ICRP recommendations. Results: The derived DRLs are presented as [median CTDIvol (mGy): median DLP (mGy·cm)]. For (<1 yr): Head: 13:187, Chest: 0.4:7, AP: 0.9:19, CAP: 0.4:10. For (1-5 yrs): Head: 16:276, Chest: 1:22, AP: 1.5:58, CAP: 1.6:63. For (6-10 yrs): Head: 19:332, Chest: 1.4:35, AP: 1.9:74, CAP: 2:121. For (11-15 yrs): Head: 21:391, Chest: 3:86, AP: 4.1:191, CAP: 3:165. We observed that both the CTDIvol and DLP DRL values increase with patient age. Weight-based DRLs follow similar trends for CTDIvol, while DLP values show noticeable variations in Chest and AP examinations. Conclusions: The study findings highlight the need for review and optimisation of certain scanning protocols, particularly for chest and AP examinations. The derived DRLs are consistent with findings from other studies. The study recommends establishing national paediatric DRLs to enhance radiology practice across the country and ensure adherence to international safety standards.

To report on a dose survey conducted by the French societies of radiology and paediatric imaging (SFR and SFIPP) and the French public service expert in nuclear and radiological risks (IRSN), and to suggest new diagnostic reference levels (DRLs) for paediatric CT. Dose reports concerning children aged 0-15years and five CT procedures (brain, petrous bone, mediastinum, lung and abdomen-pelvis) performed in 2015-2016 were collected from 15 imaging departments on a voluntary basis. Volume CT dose index (CTDIvol) and dose-length product (DLP) were recorded for at least 10 patients per procedure, per centre and per age group. New DRLs were calculated as the 3rd quartiles of the distributions of the median values. Results from 3253 CT examinations were obtained. The exposure levels observed were much lower than for the previous surveys (2007-2008 and 2010-2013) and among the lowest values currently published. A good homogeneity between facilities was also observed. New DRLs are proposed for each procedure and age group. This new survey contributes to the continuing optimisation process in French paediatric CT practice. Its results have been recently used to update the national paediatric CT DRLs. • New national diagnostic reference levels (DRLs) are proposed for several paediatric CT procedures. • The DRLs proposed for brain, chest and abdomen-pelvis procedures are among the lowest published worldwide.

Purpose. Definition of new national diagnostic reference levels (DRLs) for volume computed tomography dose index (CTDIvol) and dose length product (DLP) for neuro-paediatric CT examinations depending on the medical indication. Methods. Paediatric cranial CT data sets acquired between January 2013 and December 2016 were retrospectively collected between July 2016 and March 2017 from eight of the largest university and cantonal hospitals that perform most of the neuro-paediatric CTs in Switzerland. A consensus review of CTDIvol and DLP was undertaken for three defined anatomical regions: brain, facial bone, and petrous bone, each with and without contrast medium application. All indications for cranial CT imaging in paediatrics were assigned to one of these three regions. Descriptive statistical analysis of the distribution of the median values for CTDIvol and DLP yielded values in the minimum, maximum, 25th percentile (1st quartile), median (2nd quartile), and 75th percentile (3rd quartile). New DRLs for neuro-paediatric CT examinations in Switzerland were based on the 75th percentiles of the distributions of the median values of all eight centres. Where appropriate, values were rounded such that the DRLs increase or at least remain constant as the age of the patient increases. Results. Our results revealed DRLs for CTDIvol and DLP up to 20% lower than the DRLs used so far in Switzerland and elsewhere in Europe. Conclusions. This study provides Swiss neuro-paediatric CT DRL values to establish optimum conditions for paediatric cranial CT examinations. Periodic national updates of DRLs, following international comparisons, are essential.

This preliminary study aims towards the establishment of regional diagnostic reference levels (DRLs) for routine adult computed tomography (CT) examinations. The study was performed on 54 CT facilities from four African countries (Ghana, Kenya, Namibia and Senegal) and the results compared with international DRLs. Data were collected from facilities using a structured questionnaire provided by the International Atomic Energy Agency. Dose descriptors (volume computed tomography dose index [CTDIvol] and dose length product [DLP]) evaluations were performed on CT head and body phantoms for head, chest and abdomen CT examination protocols using standard methods. The estimated dose indices were compared with console-displayed dose values. Experienced radiologists accepted the diagnostic image quality of the images as per departmental imaging requirements. Median CTDIvol and DLP data from each facility were compiled to estimate the typical dose in each country. National DRLs were established based on the 75th percentile of median values, whereas the regional DRLs were based on the median of the national DRLs. Comparison of measured CTDIvol with console values of all facilities in all four countries was within 20% as recommended. The established CTDIvol DRLs for head CT, chest CT and abdomen CT were 60.9mGy, 15.2mGy and 15.7mGy, respectively. Similarly, that of DLP, DRLs were 1259mGy.cm, 544mGy.cm and 737mGy.cm, respectively for head CT, chest CT and abdomen CT. The established DRLs from this study were comparable to DRLs from other countries with some variations. This study would serve as baseline for establishment of a more generalized regional adult CT DRLs for Africa.

Background.Patients, especially children, are exposed to substantially high doses of ionising radiation during computed tomography (CT) procedures. Children are several times more susceptible to ionising radiation than adults. Diagnostic reference levels (DRLs) are an important tool for monitoring and optimising patient radiation exposure from radiological procedures. The aim of this study is to estimate the ionising radiation exposure doses and set local DRLs for head CT examinations according to age and to compare local DRLs with national and European DRLs and with literature data in other countries.Materials and methods.Scan parameters of single-phase head CT examinations were collected. Patients were grouped by age in the following intervals: <1, 1−5, 5−10, 10−15 and 15−18 years. Local age-based DRLs set as the 3rd quartile of the median dose-length product (DLP) were calculated. Literature analysis was performed on PubMed search engine on inclusion criteria: publication date 2015–2020, used keywords paediatric computed tomography, paediatric CT, diagnostic reference levels (DRLs). The 23 articles discussing paediatric DRLs were further analysed.Results.Data was collected from 194 paediatric head CT examinations performed in 2019. The median DLP values for head CT were 144.3, 233.7, 246.4, 288.9, 315.5 for <1, 1−5, 5−10, 10−15 and 15−18 years old groups. Estimated local DRLs for head CT examinations are 170, 300, 310, 320, 360 mGy*cm for <1, 1−5, 5−10, 10−15 and 15−18 years age groups respectively and 130, 210, 275, 320 mGy*cm for 0−3 months, 3 months−1 year, 1−6 years and ≥ 6 years age groups respectively. Conclusions.Results of this study showed that settled new local DRLs of head CT examinations were 2–4 times lower than national DRLs and about 2 times lower than European DRLs. Moreover, the study indicated that paediatric head CT doses are significantly lower in comparison with those indicated in the majority of published data from other hospitals over the last 6 years. Patient dose assessment and local DRLs establishment plays important role in future exposure optimisation.

To update the national diagnostic reference levels (DRLs) for adult CT in Switzerland using dose management software and to compare them to the previous Swiss DRLs from 2010. CT dose data from 14 radiological institutes with a total of 50 CT scanners were collected with locally installed dose management software between 2014 and 2017. Data were assigned to 15 defined master protocols. Data cleaning steps were developed and adjusted individually for each participating institute and protocol. The DRLs for each master protocol were calculated as the 75th percentile of the distribution of the median volume computed tomography dose index (CTDIvol) and dose-length product (DLP) values per CT scanner. In total, 220,269 CT exams were available after data cleaning. Updated DRLs showed a clear trend towards lower doses compared with previous DRLs. The average relative change in the DRLs for CTDIvol was - 30% (0 to - 47%) and - 22% for DLP (+ 20 to - 40%). The largest relative decrease in the DRL for DLP was observed for the cervical spine protocol (- 40%), the two chest protocols (chest, - 37%; and exclusion of pulmonary embolism, - 33%), and the two neck protocols (neck, - 32%; and carotid angiography, - 28%). The DRLs for other protocols, for example the head and the abdomen-pelvis protocol, showed smaller relative changes (- 11% and - 17%). The updated national DRLs are substantially lower than the previous values from 2010, demonstrating technological progress and the efforts of the radiological community to lower CT radiation exposure. • Dose management software allows the establishment of DRLs based on big data. • Updated Swiss DRLs for adult CT are substantially lower compared with those from 2010. • Swiss DRLs are low compared with other national DRLs.

Background:To date in Saudi Arabia, a limited number of studies conducted to assess radiation doses received by pediatrics in computed tomography (CT) brain procedure. National diagnostic reference levels (NDRL) have been established for adults, but neither NDRL’s nor Local diagnostic reference levels (LDRL) have been established for pediatric patients. Objective: This study aimed to assess radiation doses experienced by pediatric patients in CT brain procedure, and derive LDRLs. Materials and methods: The values of three radiological indexes: volume CT dose index (CTDIvol) and dose-length product (DLP) were assessed. Then effective dose (ED) were estimated, and LDRLs are suggested for CT procedures based on data retrieved from 353 pediatric patients aged between 0 and 15 years old. LDRLs were estimated based on age and weight. Results: Built on 75 percent of the median distribution of the CTDIvol and DLP values, weight assemblage LDRL values ranged from 12.29 to 28.72 mGy and from 173.32 to 565.38 mGy.cm, respectively, whereas age assemblage LDRL values ranged from 11.76 to 25.07 mGy and from 147.04 to 479.23 mGy.cm, respectively. Conclusion: This study derived the typical CTDIvol, DLP, and ED received by pediatric patient during CT brain procedure in Saudi Arabia. Then, LDRLs were proposed based on age and weight for pediatric patients aged between 0 to 15 years old.

Quality assurance in CT: implementation of the updated national diagnostic reference levels using an automated CT dose monitoring system

CT scan is a modality that produces a higher radiation dose compared to other modalities in radiodiagnostic installations. The radiation dose received by patients from examinations with this CT scan device is expressed in the volume CT Dose Index (CTDIvol) and Dose Length Product (DLP), which are dose indicators from the Indonesian Diagnostic Reference Level (DRL) value regulated in the Decree of the Head of the Nuclear Energy Regulatory Agency (BAPETEN) nationally. However, the CTDIvol value is only an indicator of the output dose from the CT scan, and the DLP value is an indicator of the total dose during the examination, which is influenced by the length of the scan. Both do not represent the specific dose received by the patient because the patient's dose depends not only on the output dose but also on the patient's characteristics. The patient's dose, which includes the output dose and patient characteristics, is called the Size-Specific Dose Estimate (SSDE), which is used to estimate the dose received by the patient by including a correction factor depending on the patient's dimensions. This study aims to calculate the SSDE value in a CT Head examination with a standard protocol using the same type of device, namely a 128-slice CT scan in several hospitals. The values of CTDIvol and DLP patients are obtained from the dose report displayed on the CT scan monitor screen in the IndoseCT software. The patient samples studied were patients undergoing CT Head examinations from March 2023 to February 2024, with 100 patients in each hospital. The results of this study obtained local DRL values based on SSDE calculated at Indriati Hospital, Moewardi Hospital, Sleman Hospital, and the National Brain Center Hospital and then compared them with the national TPD values. Based on the SSDE value from Indriati Hospital, the TPD value was 30.26 mGy, Sleman Hospital was 39.5 mGy, Dr. Moewardi Hospital was 49.3 mGy, and RSPON was 51.7 mGy. The TPD value of CT Head examinations without contrast from each hospital was still below the national TPD value of 60 mGy. Keywords: CT scan, diagnostic reference level (DRL), local DRL, national DRL, Size-Specific Dose Estimate (SSDE), IndoseCT.