Maltese CT doses for commonly performed examinations demonstrate alignment with published DRLs across Europe

This work recommends dose reference levels (DRLs) for abdomen, chest and head computerised tomography (CT) examinations in Malta as the first step towards national CT dose optimisation. Third quartiles volume CT dose index values for abdomen: 12.1 mGy, chest: 13.1 mGy and head: 41 mGy and third quartile dose-length product values for abdomen: 539.4, chest: 492 and head: 736 mGy cm(-1) are recommended as Maltese DRLs derived from this first Maltese CT dose survey. These values compare well with DRLs of other European countries indicating that CT scanning in Malta is consistent with standards of good practice. Further work to minimise dose without affecting image quality and extending the establishment of DRLs for other CT examinations is recommended.     

Patient doses in paediatric CT: feasibility of setting diagnostic reference levels

Despite the fact that doses to paediatric patients from computed tomography (CT) examinations are of special concern, only few data or studies for setting of paediatric diagnostic reference levels (DRLs) have been published. In this study, doses to children were estimated from chest and head CT, in order to study the feasibility of DRLs for these examinations. It is shown that for the DRLs, patient dose data from different CT scanners should be collected in age or weight groups, possibly for different indications. For practical reasons, the DRLs for paediatric chest CT should be given as a continuous DRL curve as a function of patient weight. For paediatric head CT, DRLs for a few age groups could be given. The users of the DRLs should be aware of the calibration phantom applied in the console calibration for different paediatric scanning protocols. The feasibility of DRLs should be re-evaluated every 2-3 y.     

Patient doses in CT examinations in Switzerland: implementation of national diagnostic reference levels

Diagnostic reference levels (DRLs) were established for 21 indication-based CT examinations for adults in Switzerland. One hundred and seventy-nine of 225 computed tomography (CT) scanners operated in hospitals and private radiology institutes were audited on-site and patient doses were collected. For each CT scanner, a correction factor was calculated expressing the deviation of the measured weighted computed tomography dose index (CTDI) to the nominal weighted CTDI as displayed on the workstation. Patient doses were corrected by this factor providing a realistic basis for establishing national DRLs. Results showed large variations in doses between different radiology departments in Switzerland, especially for examinations of the petrous bone, pelvis, lower limbs and heart. This indicates that the concept of DRLs has not yet been correctly applied for CT examinations in clinical routine. A close collaboration of all stakeholders is mandatory to assure an effective radiation protection of patients. On-site audits will be intensified to further establish the concept of DRLs in Switzerland.     

Patient doses using multidetector computed tomography scanners in Kenya

Assessment of patient dose attributed to multislice computed tomography (CT) examination. A questionnaire method was developed and used in recording the patient dose and scanning parameters for the head, chest, abdomen and lumbar spine examinations. The patient doses due to brain, chest and abdomen examination were above the international diagnostic reference levels (DRLs) by factors of between one and four. The study demonstrated that the use of multislice CT elevates patient radiation dose, justifying the need for local optimised scanning protocols and the use of institutional DRL for dose management without affecting diagnostic image quality.     

Image quality and patient dose in computed tomography examinations in Greece

The purpose of this study is to evaluate image quality of various computed tomography (CT) scanners installed in Greece, as well as to investigate patient doses from common CT examinations. An image quality survey was performed in 44 CT scanners countrywide. The imaging performance of the systems was evaluated by measurements of certain parameters, such as image noise, spatial uniformity, high- and low-contrast resolution and slice thickness accuracy. Moreover, preliminary results of patient dose survey are presented. Concerning image quality, 80 % of the scanners were found to be in compliance with the national legislation and relative international guidelines for all the examined parameters. Weighted CT dose index and dose-length product values for chest and abdomen routine examinations were generally below the dose reference levels (DRLs) suggested by the European Commission. However, some scanners were found to deliver significantly higher doses than the suggested DRL for head routine examinations. Finally, differences in the performance among scanners of the same type and similar age were observed, pointing out the importance of frequent calibration, routine quality control and proper maintenance.     

Towards dose reduction in CT: patient radiation dose assessment for CT examinations at university health center in Canada and comparison with national diagnostic reference levels

Dose indicators such as the computed tomography dose index (CTDI) and dose-length product (DLP) were gathered for all routine abdomen-pelvis, chest and head examinations performed on all computed tomography (CT) scanners at a University Health Center (UHC) in Canada. These indicators were analysed and compared with the range of diagnostic reference levels (DRLs) suggested by Health Canada and with DRLs in other countries. Mean DLP values varied from one scanner to another, but mean values at the UHC (750 mGy cm(-1) for abdomen-pelvis CT, 349 mGy cm(-1) for chest CT and 1181 mGy cm(-1) for head CT) were all below the upper limit of the range of DRLs suggested by Health Canada. Local DRLs at the UHC were set to 810 mGy cm(-1) for abdomen-pelvis CT, 345 mGy cm(-1) for chest CT and 1205 mGy cm(-1) for head CT. Results, however, show the need for protocols revisions, since some scanners exhibit mean DLP values slightly below or above the upper limit of the range of DRLs suggested by Health Canada.     

Estimation of patient doses for common diagnostic X-ray examinations in Latvian hospitals, analysis of radiographic techniques and comparison with European guidelines

This article deals with the estimation of doses received by patients undergoing radiological examinations in order to establish dose reference levels (DRLs) in Latvia. Several large hospitals, small hospitals and private practices were selected for patient dose measurements. The measurements were carried out using calibrated thermoluminiscence dosemeters attached to the patient's skin. Exposure parameters and patient's data were recorded. The entrance surface doses (ESDs) to patients undergoing several common X-ray examinations (chest AP/PA, chest LAT, lumbar spine AP/PA, lumbar spine LAT and pelvis) were measured. Data concerning the kV(p) settings, used type of films, focus-film distance and the ESD values were analysed and compared with those recommended by the European Community (EC). Among the different hospitals and private practices, discrepancies in the patient doses and techniques used for the examination were found, where the doses exceeded the EC recommended values owing to a very low kV(p) and a very low sensitivity of the screen film combinations used.     

Adult reference levels in diagnostic and interventional radiology for temporary use in Switzerland

This work aims at establishing a set of diagnostic reference levels (DRLs) for various types of examinations performed in diagnostic and interventional radiology. The average doses for 257 types of radiological examinations were established during the 1998 nationwide survey on the exposure of the Swiss population by radiodiagnostics. They were calculated using appropriate dosimetric models and average technical parameters. The DRLs were derived from the average doses using a multiplying factor of 1.5. The DRLs obtained were rounded and compared to the data reported in the literature. The results are in most cases comparable to the DRLs determined by the 3rd-quartile method. These discrepancies registered in some cases, particularly for complex examinations, can be explained by significant differences in the protocols and/or the technical parameters used. A set of DRLs is proposed for a large number of examinations to be used in Switzerland as temporary values until a national dosimetric database is set up.     

Management of patient dose in radiology in the UK

Programmes to manage patient dose in radiology are becoming a higher priority as the number of imaging examinations and the proportion of higher dose computed tomography (CT) and complex interventional procedures all continue to rise. Such programmes have a number of components and their implementation in UK hospitals, which have been developing such programmes over two decades, is described. As part of any programme to manage patient doses, elements should be in place for both justification and optimisation. The system for justification needs to be robust in order to minimise the number of unnecessary procedures and requires the provision of training in radiation protection for medical and other staff to ensure that they understand the risks. Optimisation of X-ray techniques requires performance tests on equipment at installation and regularly thereafter, linked to surveys of patient doses. Confirming the performance of the available options on fluoroscopy and CT equipment is essential and the information obtained should be available to radiographers and radiologists, so they can make informed choices in developing imaging protocols. Patient doses should be compared with diagnostic reference levels set in terms of measured dose quantities to allow the identification of equipment that is giving higher doses. Taking the next step of analysing results to determine the reasons for high doses is crucial and requires a link with the equipment performance tests and an understanding of the underlying physics. Medical physics services play an important role at the hub of the dose management programme for carrying out tests, organising surveys, making recommendations on optimisation strategies and training other staff in radiation protection, performance testing and dose reduction. Programmes for management of patient doses in UK hospitals were first set up in the late 1980s by medical physicists and have been developed since that time to keep pace with the developments in technology. Regional departments serving several hundred or a thousand X-ray units form the model followed in most regions. This paper describes the form of patient dose management programmes in the UK. It also gives guidance that might be useful to others that are now embarking on the same journey.     

Radiation exposure and dose evaluation in intraoral dental radiology

In this study, dose area product measurements have been performed to propose diagnostic reference levels (DRLs) in intraoral dental radiology. Measurements were carried out at 60 X-ray units for all types of intraoral examinations performed in clinical routine. The third quartile values calculated range from 26.2 to 87.0 mGy cm(2). The results showed that there exists a large difference between the patient exposures among different dental facilities. It was also observed that dentists working with faster film type or higher tube voltage are not always associated with lower exposure. The study demonstrated the necessity to have the DRLs laid out as guidelines in dental radiology.     

Automatic computed tomography patient dose calculation using DICOM header metadata

The present work describes a method that calculates the patient dose values in computed tomography (CT) based on metadata contained in DICOM images in support of patient dose studies. The DICOM metadata is preprocessed to extract necessary calculation parameters. Vendor-specific DICOM header information is harmonized using vendor translation tables and unavailable DICOM tags can be completed with a graphical user interface. CT-Expo, an MS Excel application for calculating the radiation dose, is used to calculate the patient doses. All relevant data and calculation results are stored for further analysis in a relational database. Final results are compiled by utilizing data mining tools. This solution was successfully used for the 2009 CT dose study in Luxembourg. National diagnostic reference levels for standard examinations were calculated based on each of the countries' hospitals. The benefits using this new automatic system saved time as well as resources during the data acquisition and the evaluation when compared with earlier questionnaire-based surveys.     

Fluroscopy in paediatric fractures--setting a local diagnostic reference level

BACKGROUND: The ionizing radiations (Medical Exposure) Regulation 2000 has made it mandatory to establish diagnostic reference levels (DRLs) for all typical radiological examinations. OBJECTIVES: We attempt to provide dose data for some common fluoroscopic procedures used in orthopaedic trauma that may be used as the basis for setting DRLs for paediatric patients. MATERIALS AND METHODS: The dose area product (DAP) in 865 paediatric trauma examinations was analysed. Median DAP values and screening times for each procedure type along with quartile values for each range are presented. RESULTS: In the upper limb, elbow examinations had maximum exposure with a median DAP value of 1.21 cGy cm2. Median DAP values for forearm and wrist examinations were 0.708 and 0.538 cGy cm2, respectively. In lower limb, tibia and fibula examinations had a median DAP value of 3.23 cGy cm2 followed by ankle examinations with a median DAP of 3.10 cGy cm2. The rounded third quartile DAP value for each distribution can be used as a provisional DRL for the specific procedure type.     

Measurement of radiation dose in dental radiology

Patient dose audit is an important tool for quality control and it is important to have a well-defined and easy to use method for dose measurements. In dental radiology, the most commonly used dose parameters for the setting of diagnostic reference levels (DRLs) are the entrance surface air kerma (ESAK) for intraoral examinations and dose width product (DWP) for panoramic examinations. DWP is the air kerma at the front side of the secondary collimator integrated over the collimator width and an exposure cycle. ESAK or DWP is usually measured in the absence of the patient but with the same settings of tube voltage (kV), tube current (mA) and exposure time as with the patient present. Neither of these methods is easy to use, and, in addition, DWP is not a risk related quantity. A better method of monitoring patient dose would be to use a dose area product (DAP) meter for all types of dental examinations. In this study, measurements with a DAP meter are reported for intraoral and panoramic examinations. The DWP is also measured with a pencil ionisation chamber and the product of DWP and the height H (DWP x H) of the secondary collimator (measured using film) was compared to DAP. The results show that it is feasible to measure DAP using a DAP meter for both intraoral and panoramic examinations. The DAP is therefore recommended for the setting of DRLs.     

Local diagnostic reference levels for some common diagnostic X-ray examinations in Tehran county of Iran

Various researchers who have carried out national and international surveys have reported wide variations in patient dose arising from specific X-ray examinations. This study was carried out as a part of a comprehensive project to establish national diagnostic reference level (NDRL), for the first time, in Iran. Seven most common X-ray examinations in 11 projections were included. Thermo luminescence dosimeters (TLD-100) were used to measure entrance surface doses (ESDs). The study group consisted of 535 patients who were referred for X-ray examinations to 12 randomly selected public hospitals in Tehran County. Minimum, median, mean, maximum, first and third quartile values of ESDs are reported. Our results are evident that mean dose values of patients undertaking a specific examination are widely different in various hospitals. Wide dose differences may emerge from complex causes, but in general, low peak kilovoltage and high milli Amperes are associated with higher doses. The results of this work together with further data expected to emerge from the work in progress will provide a useful base to establish Iran's DRLs.     

Radiation doses in common X-ray examinations carried out in two dedicated paediatric hospitals

In this study, the entrance surface dose (ESD) and the respective effective dose (E) were determined for paediatric patients undergoing various common radiological examinations in two dedicated paediatric hospitals. Measurements of ESD were carried out in 289 examinations using thermoluminescent dosemeters. The patients were categorised according to their age and the mean ESD and E values were determined for each examination and age category. These ESD values were compared with the existing diagnostic reference levels (DRLs). In both hospitals there were cases where the DRLs were exceeded but in one of them this was rather the general rule, since additionally to the routine use of grid and low tube potential settings, occasional use of fluoroscopy for positioning check was also observed. While the remedial actions required to appropriately reduce the doses were clearly identified, this cannot be achieved without the cooperation of medical physicists with operators and radiologists.     

Unsolved or unsolvable problems with diagnostic reference levels

Diagnostic reference levels (DRLs) for X-ray examinations have been introduced in many countries, among others in most European countries, as a consequence of the Directive on Medical Exposures from 1997. The concept seems to be straight forward, but when implementing it into practice a number of problems arise. The results are dependent on how the dose data are measured and assessed. The interpretation of the results must be performed with great care giving due consideration to the fact that X-ray examinations are very complex and hence not very well characterised by a single figure. In this presentation the various parameters influencing the patient dose are discussed and suggestions are given on how these are managed so as to get the best outcome. When these intentions are followed diagnostic reference levels will be a powerful tool for the optimisation process.     

Estimation of doses received by patients undergoing radiological examinations in Greece

This study deals with the estimation of doses received by patients undergoing radiological examinations in order to establish diagnostic reference levels (DRLs) within the process of optimisation of patients' exposure in Greece. Six large hospitals in Athens were selected and 385 patients made up the sample. The entrance surface doses (ESDs) to patients undertaking five common X ray examinations (chest, cervical spine, lumbar spine AP and LAT, pelvis) were estimated using both thermoluminescence dosemeters (TLDs) attached to the patient's skin and an ionisation chamber for air kerma measurements. Exposure settings and patient's data were recorded. Results concerning the kilovoltage and focus-to-film-distance (FFD) settings and the ESD values were analysed and compared to those recommended by the EU. Discrepancies in the patient doses and techniques used for the examinations studied were found among the different hospitals denoting the importance of establishing a national quality assurance programme and examination protocols to ensure patient doses are kept as low as possible. All the examinations studied fulfilled the EU recommendations except that for the chest where the doses were considerably higher due to the use of low kVP settings.     

First results on patient dose measurements from conventional diagnostic radiology procedures in Serbia and Montenegro

The objective of this work is to assess patient doses for the most frequent X-ray examinations for the first time in Serbia and Montenegro. A total of 510 procedures for 11 different examination categories in 3 general hospitals were analysed. Mean and median entrance surface air kerma (ESAK) and kerma area product (KAP) values followed by mean effective doses were reported. Using X-ray tube output data, ESAK for each radiographic examination was calculated, as well as the effective dose for each patient. Except for chest PA examination, all estimated doses are less than stated European and International Atomic Energy Agency (IAEA) reference levels for simple radiographic examinations. For complex examinations involving fluoroscopy and radiography total KAP was measured and contributions from fluoroscopy and radiography were assessed. The study of KAP confirms that the dose level for complex fluoroscopy investigations is closely related to the technique and individual patient variation in terms of fluoroscopy time and number of radiography exposures. The obtained values are comparable to those reported in the UK. Survey data are aimed aid development of a national quality control and radiation protection programme for medical exposures.     

Radiation exposure to children in intraoral dental radiology

In this study, dose area product (DAP) measurements have been performed aiming at establishing diagnostic reference levels (DRLs) in paediatric intraoral dental radiology. Measurements were carried out at 52 X-ray units for all types of intraoral examinations performed in clinical routine. Not all X-ray units have pre-set child exposure settings with reduced exposure time or in some cases lower tube voltage. Child examinations are carried out using adult exposure settings at these units, which increases the DAP third quartile values by up to 50%. For example, third quartile values for periapical examination ranges from 14.4 to 40.9 mGy cm(2) for child settings and 20.6 to 48.8 mGy cm(2) when the adult settings are included. The results show that there exists a large difference between the patient exposures among different dental facilities. It was also observed that clinics working with faster film type or higher tube voltage are not always associated with lower exposure.