Towards a proposition of a diagnostic (dose) reference level for mammographic acquisitions in breast screening measurements in Belgium

A diagnostic reference level (DRL) is a dose level for a typical X-ray examination of a group of patients with standard body sizes and for broadly defined types of equipment. These levels are expected not to be exceeded for standard procedures when good and normal practice regarding diagnostic and technical performance is applied. In this paper, we have calculated DRLs for screening mammography in Belgium. The 95th percentile of the mean average glandular dose is 2.46 mGy. The DRL based on polymethyl methacrylate (PMMA) measurements was 2.08 mGy. Correlation coefficient (R) between doses from patient studies and phantom studies was 0.90, with an average underestimation of the phantom measurements of 15% for systems that use only Mo/Mo anode/filter. For the centres that use other anode/filters, there is not enough scientific evidence that a single phantom measurement of a standard PMMA block is representative for the patient dose.     

Radiation doses to patients undergoing enteroclysis

Enteroclysis is a minimally invasive radiographic examination of the small intestine. During the procedure, considerable radiation dose is delivered to the patients. This study intends to: (a) evaluate the radiation dose to the patient using thermoluminescent dosemeters (TLDs, according to the protocol used at Radiology Department, University Hospital of Larissa, Greece; (b) estimate the thyroid surface dose (TSD) and doses to some radiosensitive organs located in the irradiation field. A total of 46 patients was examined. Patients were divided into two groups according to the digital X-ray machine used. The mean entrance surface dose (ESD) was 601.2 ± 96.2 mGy and the mean fluoroscopy time was 8.5 ± 3 min, while the mean TSD was 0.34 ± 0.6 mGy. The ESD for group A was lower by 20 % than group B due to fluoroscopic mode used. The dose values were higher than those in the literature. A local diagnostic reference level was introduced for further patient dose optimisation.     

Dose-area product measurements and determination of conversion coefficients for the estimation of effective dose in dental lateral cephalometric radiology

A study has been carried out to propose diagnostic reference levels (DRLs) for lateral cephalometric radiology in Germany based on the dose-area product (DAP). DRLs were proposed separately for child and adult exposure settings which are 26.4 and 32.6 mGy cm2, respectively. Organ absorbed doses from lateral cephalometric radiology were also measured using thermoluminescence detectors (TLDs) and an adult anthropomorphic phantom specially design for dosimetric study in dental radiology. Effective doses were then calculated using three different techniques where the salivary gland and brain tissue were given different weighting factors. Conversion coefficients for estimating effective dose from DAP value derived in this study range from 0.042 to 0.149 microSv/mGy cm2.     

Dose area product measurement for diagnostic reference levels and analysis of patient dose in dental radiography

In this study, diagnostic reference levels (DRLs) were suggested and patient doses were analysed through the dose-area product value in dental radiography. In intraoral radiography, at three sites, i.e. molar, premolar and incisor on the maxilla and acquired third quartile values: 55.5, 46 and 36.5 mGy cm(2), respectively, were measured. In panoramic, cephalometric and cone beam computed tomography, the values were 120.3, 146 and 3203 mGy cm(2) (16 × 18 cm), respectively. It has been shown that, in intraoral radiography, the patient dose changes proportionally to the value of mA s, but the change in extraoral radiography in response to mA s could not be confirmed. The authors could confirm, however, the difference in dose according to the manufacturer in all dental radiography examinations, except for panoramic radiography. Depending on the size of hospital, there were some differences in patient dose in intraoral radiography, but no difference in patient dose in extraoral radiography.     

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.     

Retrospective patient dose analysis of a digital radiography system in routine clinical use

The log files generated in the flat-panel detector based digital radiography systems (Philips Digital Diagnost) at 11 different hospitals were used to acquire data regarding the dose-area product (DAP) and the entrance air kerma (EAK) for all X-ray examinations performed in routine clinical use. A retrospective statistical analysis of the data with respect to the dose levels was performed for several examination types. The resulting average dose levels were compared with the diagnostic reference levels (DRLs). While for the same type of examination the median dose level at different hospitals could differ by up to a factor of 5, almost all the dose levels were found to be much below the published DRL. Only in one hospital for one type of examination (Thorax PA) the DRL for the DAP was slightly exceeded, while for the same site and examination the EAK was still below the DRL. In conclusion, examination log files can be used for retrospective dose analysis and correlation with DRLs.     

Patient dose measurements in diagnostic radiology procedures in Montenegro

It was the aim of the study presented here to estimate for the first time patient dose levels in conventional diagnostic radiology in Montenegro. Measurements of patient dose in terms of entrance surface air kerma (ESAK) and kerma-area product (KAP) were performed on at least 10 patients for each examination type, in each of five randomly selected health institutions in Montenegro, so that a total of 872 patients for 16 different examination categories were included in the survey (817 patients for 1049 radiographies and 55 fluoroscopy patients). Exposure settings and individual data were recorded for each patient. Mean, median and third quartile values ESAK of patient doses are reported. The estimated mean ESAK values obtained are as follows: 4.7 mGy for pelvis anteroposterior (AP), 4.5 mGy for lumbar spine AP, 7.8 mGy for lumbar spine lateral (LAT), 3.1 mGy for thoracic spine AP and 4.3 mGy for thoracic spine LAT. When compared with the European diagnostic reference values, the mean ESAK for all studied examination types are found to be below the reference levels, except in chest radiography. Mean ESAK values for chest radiography are 0.9 mGy for posteroanterior (PA) projection and 2.0 mGy for LAT. The results exhibit a wide range of variation. For fluoroscopy examinations, the total KAP was measured. The mean KAP value per procedure for barium meal is found to be 22 Gy cm(2), 41 Gy cm(2) for barium enema and 19 Gy cm(2) for intravenous urography. Broad dose ranges for the same types of examinations indicate the necessity of applying practice optimisation in diagnostic radiology and establishment of national diagnostic reference levels.     

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.     

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.     

Evaluation of patient doses due to fluoroscopic exposures

The present study measures entrance surface doses of radiation administered to patients during various fluoroscopic procedures using a dose-area product meter as well as the duration of each procedure. A conversion factor for entrance skin dose to patients was calculated. The average dose to patient during the insertion of intravenous hyperalimentation was 10.2 (maximum, 74.0) mGy, during a barium meal, 58.4 (maximum, 184.0) mGy, for endoscopic retrograde cholangio-pancreatography (ERCP), 97.3 (maximum, 376.0) mGy and for a barium enema, 86.1 (maximum, 271.0) mGy. Doses tended to increase in the abdominal domain and when patients undergo not only diagnostic evaluation but also treatment requiring procedures such as drainage. The management of radiation doses determined using a dose-area product meter is very important and that of individual patients is enabled using the Radiation Information System (RIS).     

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.     

Use of the mini C-arm for wrist fractures--establishing a diagnostic reference level

The establishment of diagnostic reference levels (DRLs) forall typical radiological examinations became mandatory followingthe implementation of the Ionising Radiations (Medical Exposure)Regulations Act 2000. At present, there are no national dosageguidelines in the UK regarding use of fluoroscopy in orthopaedictrauma. The increasing popularity of the mini C-arm image intensifieramongst surgeons has led to concerns regarding use of ionizingradiation by personnel who have not been trained in radiationprotection. It is therefore essential to have formal protocolsfor use of the mini C-arm to comply with the law and to maintainsafe clinical practice. It is attempted to provide dose datafor wrist fracture manipulations that may be used as a basisfor setting a DRL for this procedure. Screening times were recordedfor 80 wrist manipulations in a fracture clinic setting usinga mini C-arm image intensifier. A DRL was set using the thirdquartile value for screening time. The median screening timefor wrist fractures was 20 s with a range from 1 to 177 s. Thethird quartile value for screening time was 34 s. This valuecan be used as a provisional DRL for wrist fracture manipulations.The DRL is a quantitative guide for the optimisation of radiologicalprotection. IR(ME)R 2000 states that if it is consistently exceededby an individual operator or a piece of equipment, investigationand remedial action must be taken. We recommend that traumaunits establish their own local DRLs for common procedures asmade mandatory by legislation.     

Entrance radiation doses during paediatric cardiac catheterisations performed for diagnosis or the treatment of congenital heart disease

The purpose of this study was to estimate the radiation exposure of children, during cardiac catheterisations for the diagnosis or treatment of congenital heart disease. Radiation doses were estimated for 45 children aged from 1 d to 13 y old. Thermoluminescent dosemeters (TLDs) were used to estimate the posterior entrance dose (DP), the lateral entrance dose (DLAT), the thyroid dose and the gonads dose. A dose-area product (DAP) meter was also attached externally to the tube of the angiographic system and gave a direct value in mGy cm2 for each procedure. Posterior and lateral entrance dose values during cardiac catheterisations ranged from 1 to 197 mGy and from 1.1 to 250.3 mGy, respectively. Radiation exposure to the thyroid and the gonads ranged from 0.3 to 8.4 mGy to 0.1 and 0.7 mGy, respectively. Finally, the DAP meter values ranged between 360 and 33,200 mGy cm2. Radiation doses measured in this study are comparable with those reported to previous studies. Moreover, strong correlation was found between the DAP values and the entrance radiation dose measured with TLDs.     

Optimisation of X-ray examinations in Lithuania: start of implementation in mammography

Optimisation of medical X-ray examinations is very important for the enhancement of the reliability of the examination and for the reduction of the radiation dose to patients. Results of investigations of doses to patients during mammography using thermoluminescence dosemeters at different hospitals are presented together with a brief overview of the situation for mammography in Lithuania. It is shown that the entrance surface air kerma varies in a broad range and differed from hospital to hospital. Nevertheless the calculated values of average glandular dose (AGD) for a 'standard' breast being relatively high were comparable with those (3.2 mGy per exposure at net optical density 1.4) currently accepted by international authorities. Differences in AGD values evaluated at different hospitals demonstrate the existing potential for optimisation of the mammography screening procedures. The results of this investigation will be included in a database for patient doses in Lithuania and used for establishing a national reference dose level for mammography. Currently, reference levels recommended by international authorities are used in Lithuania.     

Dose-area product measurements in panoramic dental radiology

In this study, dose-area product (DAP) measurements in panoramic dental radiology have been performed in Germany. The results obtained in this study were proposed as diagnostic reference levels (DRLs). A representative number of dental panoramic units, both with digital and conventional image receptors, have been chosen. Common statistical parameters such as mean, standard deviation and 3rd quartile have been calculated. For four different standard programmes, 'large adult', 'adult male', 'adult female' and 'child', the proposed DRLs are 101, 87, 84 and 75 mGy cm(2), respectively. No clear tendency to a generalised dose reduction from the transition to digital techniques has been observed. Effective doses have been calculated from E/DAP conversion factors published in literature. Even though these values differ by a factor of approximately 3, upper limits of 15.8-21.2 microSv for the four different exposure settings were derived from the data.     

Transition from screen-film to computed radiography in a paediatric hospital: the missing link towards optimisation

In paediatrics, the risks associated with ionising radiation should be a major concern, due to children's higher susceptibility to radiation effects. Measure entrance skin dose (ESD) in chest and pelvis X-ray projections and compare the results with the 'European guidelines on quality criteria for diagnostic radiographer images in paediatrics' in order to optimise radiological practice. ESD values were obtained using an ionisation chamber Diamentor M4 KDK (PTW) in 429 children, who underwent chest X-ray or pelvis X-ray in a Computed Radiography system. In the first phase of the study, data were collected according to protocols used in the department; in a second phase different tube voltage values were used according to patient weight. A third phase was carried out, only for chest X-ray, using the exposure parameters of phase 2, plus activating lateral ionisation chamber. Three paediatric radiologists blindly assessed image quality of chest X-ray, using a validated assessment available in the 'European guidelines on quality criteria for diagnostic radiographer images in paediatrics'. Considering all the patients submitted to chest X-ray, the average ESD was 0.22, 0.16 and 0.08 mGy, for phases 1, 2 and 3, respectively. For pelvis X-ray, the average ESD decreased from 1.18 mGy in phase 1 to 0.78 mGy in phase 2. Dose optimisation was achieved. ESD was reduced 63.6 and 33.9 % in chest and pelvis X-ray, respectively.     

Correlation of patient maximum skin doses in cardiac procedures with various dose indicators

In most countries of European Union, legislation requires the determination of the total skin dose received by patients during interventional procedures in order to prevent deterministic damages. Various dose indicators like dose-area product (DAP), cumulative dose (CD) and entrance dose at the patient plane (EFD) are used for patient dosimetry purposes in clinical practice. This study aimed at relating those dose indicators with doses ascribed to the most irradiated areas of the patient skin usually expressed in terms of local maximal skin dose (MSD). The study was performed in two different facilities for two most common cardiac procedures coronary angiography (CA) and percutaneous coronary interventions (PCI). For CA procedures, the registered values of fluoroscopy time, total DAP and MSD were in the range (0.7-27.3) min, (16-317) Gy cm(2) and (43-1507) mGy, respectively, and for interventions, accordingly (2.1-43.6) min, (17-425) Gy cm(2), (71-1555) mGy. Moreover, for CA procedures, CD and EFD were in the ranges (295-4689) mGy and (121-1768) mGy and for PCI (267-6524) mGy and (68-2279) mGy, respectively. No general and satisfactory correlation was found for safe estimation of MSD. However, results show that the best dose indicator which might serve for rough, preliminary estimation is DAP value. In the study, the appropriate trigger levels were proposed for both facilities.     

Evaluation of the population dose to the UK population from the National Health Service Breast Screening Programme

In the United Kingdom National Health Service Breast Screening Programme (NHSBSP), women aged between 50 and 70 y are invited for mammography every 3 y. Screening histories for each woman, over four screening rounds, were analysed. Data from five screening programmes were used to select 57 425 women into the study. Cases were selected on the basis of being between the ages of 50 and 53 at the start of the NHSBSP (i.e. between 1989 and 1992). Assessment of the outcome for each screening round for each woman involved assigning a simple outcome code. Each of the possible pathways through the four screening rounds was analysed. This comprises of 500 possible pathways. This data enabled the following information to be determined: (i) The number of times a woman attended the screening programme. (ii) The number of women referred for assessment at each screening round. This information may be used to deduce the population dose to this group of women averaged over four screening rounds. Patient doses have been monitored since the programme's inception and are typically 4.5 mGy for two-view screening. It is possible to determine the mean glandular dose received by this cohort of women over four screening rounds by multiplying the number of examinations by the mean glandular dose for a typical woman. Allowance has to be made for the number of projections taken at each screening round. Once a woman has been screened, she may be invited back for further assessment if an abnormality is found on her mammogram. A stereotactic attachment is used to determine where to place the biopsy device. Although the dose received during a normal screening mammogram is well known, the dose for a stereotactic procedure and other assessment procedures is less well known, partly because only a small part of the breast is directly irradiated during stereotaxis. However, the woman may have multiple exposures during this stage. A prospective survey of doses was completed to deduce the mean glandular dose at the first assessment stage and during stereotaxis. Numbers of films, including magnification films taken at first-stage assessment were established in the North East of England and Scotland by means of a postal survey. Average total mean glandular dose was deduced using previous survey data for the screening programme and a multiplying factor to allow for magnification film dose. On average 1.6 full field and 0.15 collimated contact films are taken for each woman (with 2.25 and 0.75 mGy film(-1)), 1.0 full field and 0.9 collimated magnification views. The mean magnification film dose to the assessed breast was 5.0 and 1.7 mGy for a collimated magnification film. A survey of 134 women at screening centres in the North East of England was performed to deduce the mean glandular dose from digital stereotaxis which is almost universally used in breast screening. A typical woman received a dose to the assessed breast of 4.5 mGy with a range of 1.3-17 mGy. This data may be used to deduce the total mean glandular dose over four screening rounds including the assessment stages. The estimated mean glandular dose to a typical woman invited to the screening programme is approximately 16 mGy, when allowance for attendance rate and assessment rate over each screening round is made. The mean glandular dose to the population is approximately 4700 Sv y(-1).     

Evaluation of patient dose in some mammography centres in Iran

High diagnostic sensitivity and specificity while maintaining the least dose to the patient is the ideal mammography. The objective of this work was to evaluate patient dose and image quality of mammograms to propose corrective actions. The image quality for 1242 patient in 7 mammography facilities in Tehran city was evaluated based on selected image quality criteria using a three-point scale. Clinical image quality, the entrance surface air kerma, the average glandular dose and optical density of films for standard PMMA phantom of 4.5 cm thickness were evaluated. The results showed that up to 72 % of mammograms were in good condition to be diagnosed, and only about 3.4 % of the images were unacceptable or with suboptimal quality. The entrance surface air kerma values were in the range of 3.8-10.5 mGy, average glandular dose 0.5-1.8 mGy and optical density of films 0.74-2.03. The image quality evaluation after correction actions, periodic image quality evaluation and using the correct equipment certainly will improve patient dose.