Patient Dose Survey Research Articles

Approaches to aspects of optimisation of protection in diagnostic radiology in six continents

There has been an expansion in the use of x-ray imaging during the last 20 years. Effective arrangements for justification of exposures as well as for optimisation of protection are crucial. The amount of effort put into the latter, the way in which it is organised and the groups carrying this out vary across the globe. A simple survey of organisational arrangements relating to performance testing of x-ray equipment, management of patient dose and other aspects of implementing optimisation has been undertaken. A total of 137 completed survey forms were received from medical physicists in 48 countries. Results for individual countries from which more responses were received, or for groups of neighbouring ones, are compared to portray variations. Some performance testing of x-ray equipment was mandated in most countries (more than 90%), with the tests being performed primarily by hospital or private medical physicists, although other groups are involved. Testing of equipment prior to clinical use was generally high for most regions, but the frequency was lower in Latin America. There was considerable variation in the frequency and regularity of subsequent testing. The prevalence of patient dose surveys was high in Europe, but lower in other continents. Organisational arrangements for testing performance of x-ray equipment, patient dose surveys and implementing optimisation of protection in medical exposures across the globe can be divided into five main groups. Hospital medical physicists take the lead in western Europe and Australia with the involvement of radiographers. Private medical physicists test equipment in Brazil, the USA and New Zealand, and have some responsibility for optimisation in Brazil. University personnel have significant involvement, together with medical physicists in eastern Europe, but the extent of the coverage is uncertain. Government personnel and service engineers carry out equipment testing in many countries of Africa and Asia, while radiographers have a significant role in Thailand and other countries where the number of medical physicists is limited. In order for dose surveys to have an impact, action must be taken upon the findings, but there must be an effective link between surveyors and radiology facility staff to ensure that this is done.

Technical and clinical breast cancer screening performance indicators for computed radiography versus direct digital radiography

To compare technical and clinical screening performance parameters between computed radiography (CR) and direct digital radiography (DR) systems. The number of women screened with CR was 73,008 and with DR 116,945. Technical and patient dose survey data of 25 CR and 37 DR systems were available. Technical performance was expressed by threshold thickness values at the mean glandular dose (MGD) level of routine practice. Clinical indicators included recall rate (RR), cancer detection rate (CDR), percentage of ductal carcinoma in situ (DCIS), percentage of cancers with T-scores smaller than 1 cm and positive predictive value (PPV). Contrast threshold values for the 0.1-mm gold disk were 1.44 μm (SD 0.13 μm) for CR and 1.20 μm (SD 0.13 μm for DR). MGD was 2.16 mGy (SD 0.36 mGy) and 1.35 mGy (SD 0.32 mGy) for CR and DR respectively. We obtained for CR, respectively DR, the following results: RR in the first round of 5.48 % versus 5.61 %; RR in subsequent rounds of 2.52 % versus 2.65 %; CDR of 0.52 % versus 0.53 %; DCIS of 0.08 % versus 0.11 %; a rate of cancers with T-scores smaller than 1 cm of 0.11 % versus 0.11 %; PPV of 18.45 % versus 18.64 %; none of them was significantly different. Our screening indicators are reassuring for the use of CR and DR, with CR operating at 60 % higher MGD. • Breast cancer screening can employ both computed (CR) and direct digital radiography (DR). • Screening performance parameters for CR and DR technology are not significantly different. • Screening parameters are in accordance with European Guidelines. • Radiation doses employed for CR are generally 60 % greater than for DR.

Reduction of Exposure of Patients and Staff to Radiation During Fluoroscopically Guided Interventional Procedures

The increase in the frequency of interventional procedures and in the number of medical specialties using fluoroscopically guided procedures together with the reevaluation of radiation risks by the International Commission on Radiological Protection (ICRP) and their impact on safety regulations has promoted several international research programs, guidelines produced by professional and scientific societies, and many valuable research articles during the last few years. This review summarizes the most important new findings and brings readers up to date on the subject of radiation safety in interventional radiology. Several key points are highlighted in the sections on guidelines of scientific and professional societies, national and regional patient and staff dose surveys, interventional procedures in pediatrics, automatic patient dose registry and analysis, occupational and lens dose evaluation, lens injury surveys, and patient dose follow-up and hybrid rooms. As a conclusion, the most relevant aspects are summarized as follows: the ICRP recommendation on the use of diagnostic reference levels for interventional procedures and new radiation thresholds for some tissue reactions; a new occupational dose limit for the lens and changes in regulation; guidelines of several medical societies on radiation safety for interventional procedures; relevant international research programs on the topic; advances in radiology systems offering standardized patient dose reports and optimized imaging protocols; more interest and actions in radiological protection training; more interest in patient dose management for pediatric procedures; concern with lens and skin radiation injuries and actions to avoid them; better postprocedural care as part of the quality programs and better clinical follow-up of patients and automatic collection and processing of individual patient doses to help in the optimization and contribute to the tracking of patient procedures and doses.

Intercomparison of patient CTDI surveys in three countries

The results of large-scale computed tomography (CT) patient dose surveys from the USA, UK and Germany undertaken during the period 1999-2001 were reviewed. The mean values for volume-weighted CT dose index (CTDI(vol)) and dose length product (DLP) were extracted. For head CT examinations, the reported values for the three surveys were similar with a mean CTDI(vol) of 59±6 mGy and a mean DLP of 760±90 mGy cm. For the body, the values for CTDI(vol) in the USA (21±5 mGy) were nearly double those in the European countries (12±2 mGy). Average head CTDI(vol) values are comparable with the diagnostic reference levels (DRLs) recommended by the European Commission and the UK Health Protection Agency, but lower than the value of 75 mGy, which is currently used in the USA. DRLs for abdominal imaging are nearly a factor of 2 lower in the UK (14 mGy) than in other parts of the European Community and the USA (25 mGy).

National survey of patient doses from whole-body FDG PET-CT examinations in France in 2011

A national survey of patient doses from 'whole-body PET-CT' examinations was conducted within all French nuclear medicine departments in 2011. Data related to injected [(18)F]-fluorodeoxyglucose (FDG) activity and to computerised tomography (CT) parameters were received from 56 positron emission tomography (PET)-CT units (answer rate: ∼60 %). The average specific injected FDG activity was equal to 4.3 MBq kg(-1), in agreement with European recommendations. The new 'time-of-flight' technology enabled to decreasing the specific activity down to 3.5 MBq kg(-1). The results have shown that current diagnostic reference levels (DRLs) for the diagnostic trunk CT are too high for CT combined with PET, only performed in France for attenuation correction and localisation, and not for diagnostic purpose. Despite wide variations between PET-CT units (4-fold factor in CTDI(vol)), DRLs equal to 8 mGy (CTDI(vol)) and 750 mGy cm (dose-length product) could be proposed for whole-body PET-CT. The average effective dose related to whole-body PET-CT examination in France has been assessed to ∼14 mSv.

A national patient dose survey and setting of reference levels for interventional radiology in Bulgaria

A national study on patient dose values in interventional radiology and cardiology was performed in order to assess current practice in Bulgaria, to estimate the typical patient doses and to propose reference levels for the most common procedures. Fifteen units and more than 1,000 cases were included. Average values of the measured parameters for three procedures-coronary angiography (CA), combined procedure (CA + PCI) and lower limb arteriography (LLA)--were compared with data published in the literature. Substantial variations were observed in equipment and procedure protocols used. This resulted in variations in patient dose: air-kerma area product ranges were 4-339, 6-1,003 and 0.2-288 Gy cm(2) for CA, CA + PCI and LLA respectively. Reference levels for air kerma-area product were proposed: 40 Gy cm(2) for CA, 140 Gy cm(2) for CA + PCI and 45 Gy cm(2) for LLA. Auxiliary reference intervals were proposed for other dose-related parameters: fluoroscopy time, number of images and entrance surface air kerma rate in fluoroscopy and cine mode. There is an apparent necessity for improvement in the classification of peripheral procedures and for standardisation of the protocols applied. It is important that patient doses are routinely recorded and compared with reference levels. • Patient doses in interventional radiology are high and vary greatly • Better standardisation of procedures and techniques is needed to improve practice • Dose reference levels for most common procedures are proposed.

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.

SU‐E‐I‐94: Survey of CT Image Quality and Patient Doses in Taiwan

Purpose: The purpose of this study is to survey the image quality and patient doses for CT in Taiwan. Methods and Materials: Dedicated researchers conducted on‐site measurements, started from March 2009 to September 2010. An ACR CT accreditation phantom (Model 464, Gammex) was used to evaluate CT image quality, including slice thickness accuracy, CT number accuracy, uniformity, noise, artifact, spatial resolution, and low contrast detectability. CT dose index (CTDI) was measured by a pencil‐type ionization chamber (10X6‐3CT, Radcal) inserted into head and body dosimetry phantoms. Representative patient doses for adult head, adult abdomen, and 5‐years pediatric abdomen examinations were evaluated according to clinical setting and on‐site measured data, including volume CTDI (CTDIvol), dose‐length product (DLP), and effective doses. The diagnostic reference levels for CTDIvol were set at the third quartile from the survey results. The criteria of pass or fail were according to ACR CT accreditation. Results: There are 446 CT scanners, including CT, PET/CT, SPECT/CT, and CT simulator, in 234 hospitals in Taiwan. The survey, which was conducted from March 2009 to September 2010, included 426 units in 226 hospitals (96% completed). The fail rates of each item of image quality ranged from less than 1% to around 80%. The mean value and third quartile value of CTDIvol are 53 and 68 mGy for adult head examinations, 18 and 18 mGy for adult abdomen examinations, and 17 and 28 mGy for 5‐ years pediatric abdomen examinations.Conclusion: The results have compared with ACR CT accreditation and gave us a view of current level of CT image quality and patient doses in Taiwan.

Comprehensive dose survey of breast screening in Ireland

The primary purpose of this study was to evaluate the impact of digital mammography screening on breast dose by analysing the results of a patient dose survey of the Irish breast screening programme. Results from the survey were used to determine a dose reference level for the screening programme. Approximately, 100 examinations were acquired for each of the digital mammography systems operational in the screening programme. Each examination consisted of two standard views of each breast. The mean glandular dose for each acquired image was calculated. The dose reference level was established by calculating the 95th percentile of the average mean glandular dose for the average compressed breast thickness of the mediolateral oblique views. The overall average mean glandular dose per examination was 2.72 ± 0.04 mGy. The average compressed breast thickness was 61.4 ± 0.03 mm. The average compression force was 109 ± 7 N. A dose reference level value of 1.75 mGy was established for the screening programme. The results of this clinical dose survey provide a valuable indication of the dose performance of modern full field digital mammographic imaging systems. The results demonstrate clearly the dose benefits of digital mammography. The dose benefit of digital screening was further demonstrated by the establishment of a comparatively lower diagnostic reference level for the screening programme. The comparison of the dose performance of individual X-ray systems with the diagnostic reference level highlights the need for more optimisation within the service.

Survey of patient doses from conventional diagnostic radiographic examinations in Syria

The aim of this study is to evaluate radiation doses received by adult patients undergoing eight routine common types of X-ray examination in Syria. These types cover chest PA, lumbar spine PA, lumbar spine LAT, urography, abdomen, pelvis and hip, head and shoulder. This work consisted of measurements for 926 X-ray examinations for patients in 26 governmental hospitals. The mean and third quartile of the dose area product (DAP) to each patient per examination have been measured. The corresponding average effective doses have been computed from the DAP measurement for each examination using NRPP X-Dose software. Comparison of the results was done with those from similar surveys published by the United Nation Scientific Committee on the Effects of Atomic Radiation (UNSCEAR, 2000, 2007). The present measurements will provide a useful baseline to establish, for the first time, national diagnostic reference levels. These results can be used in the future to evaluate the collective dose to the population from medical exposure and the radiation risks from the various radiological procedures.

Management of patient doses and diagnostic reference levels in X-ray radiography in Lithuania

Management of patient doses and determination of national or local diagnostic reference levels (DRLs) are important parts of a quality control program in X-ray diagnostics. In Lithuania, national DRLs for specific radiographic examinations are comparatively higher than those recommended by the European Commission (EC) and the International Atomic Energy Agency (IAEA). A survey of entrance surface doses (ESDs) was performed to investigate the reasons for exceeding the European and the IAEA DRLs. The first measurements showed that the average ESD for standard patients and for all examinations exceeded DRLs at approximately 25 % of the hospitals. The main problems were the use of low kilovolt technique, the lack of automatic exposure control systems or improper adjustment of them as well as inadequate training of the staff. After corrective actions, the ESD measurements were repeated. The results showed that the average patient doses were reduced almost everywhere. An additional patient dose survey for establishing new DRLs in radiography taking into account the advantages of new equipment to indicate directly the kerma area product (KAP) values was done. The ESD values were calculated from the KAP-values. The data were analysed, and the average and third quartile values were calculated. The new DRLs, in terms of ESDs, were reduced significantly in almost all radiography examinations. They are equal or lower than the IAEA and EC DRLs. Especially at thorax spine LAT, lumbar spine LAT, hip joint AP, pelvis AP and abdomen AP they are half the IAEA DRLs.

Mammography radiation dose: initial results from Serbia based on mean glandular dose assessment for phantoms and patients

The primary objective of this study is to investigate the actual mammography dose levels in Serbia and establish a baseline dose database for the future screening programme. The mean glandular dose (MGD) was assessed for standard size breast substituted by 45 mm polymethyl methacrylate (PMMA) phantom and imaged under typical clinical conditions at 30 screen-film mammography facilities. Average MGD was (1.9 +/- 1.0) mGy, with a range of 0.12-5.2 mGy. These results were used for the calculation of the initial diagnostic reference levels in mammography in Serbia, which was set to 2.1 mGy for a standard breast. At some facilities, high doses were observed and the assessed MGD was supplemented by a patient dose survey. MGD was measured for 53 women having a diagnostic mammography in cranio-caudal (CC) and mediolateral oblique (MLO) projections at the largest mammography facilities in Serbia. The parameters recorded were: age, compressed breast thickness, tube potential (in kV), tube loading (in mAs) and the MLO projection angle. The average MGD per image was 2.8 mGy for the CC projection and 4.3 mGy for the MLO projection. Dose to breast was compared with dose for PMMA phantoms of various sizes, assessed at the same facilities. The results have indicated that phantom dose values can assist in setting optimisation activities in mammography. Both phantom and patient dose values indicated unnecessary high doses in facilities with an extremely high mammography workload. For these facilities, urgent dose-reduction measures and follow-up actions were recommended.

The development of a guidance level for patient dose for CT examinations in Korea

The primary goal of this study was to analyse the state of patient doses in the field of computed tomography (CT) examinations in the Republic of Korea. All survey data including the CT applications and patient dose details were obtained from general hospitals registered in the Korean Hospital Association. The systematic analysis of the patient dose survey gives target values of the weighted computed tomography dose index (CTDI(w)) and the dose-length product (DLP). The targeted CTDI(w) values were 69, 69, 31, 19, 44, 25, 24, 20, 2, 19 and 19 mGy for the brain non-contrast enhancement (BNCE), brain contrast enhancement (BCE), neck, chest, spine, liver, pancreas, stomach, kidneys, abdomen routine and abdomen trauma protocols, respectively. The targeted DLP values were 1056, 2112, 762, 1234, 1338, 2794, 2742, 2378, 2836, 1844 and 1939 mGy cm for the BNCE, BCE, neck, chest, spine, liver, pancreas, stomach, kidneys, abdomen routine and abdomen trauma protocols, respectively. Comparing with the EUR recommendation, especially in the DLP, the adjustment of the total scan phase frequency and the shortening of the scan phase in each scan phase are needed to reduce the patients radiation exposure to international standards.

Organ doses and effective doses in pediatric radiography: Patient-dose survey in finland

Use of the effective dose in diagnostic radiology permits the radiation exposure of diverse diagnostic procedures to be quantified. Fundamental knowledge of patient doses enhances the implementation of the "as low as reasonably achievable" (ALARA) principle. To provide comparative information on pediatric examination protocols and patient doses in skull, sinus, chest, abdominal, and pelvic radiography examinations. 24 Finnish hospitals were asked to register pediatric examination data, including patient information and examination parameters and specifications. The total number of examinations in the study was 1916 (1426 chest, 228 sinus, 96 abdominal, 94 skull, and 72 pelvic examinations). Entrance surface dose (ESD) and dose-area products (DAP) were calculated retrospectively or DAP meters were used. Organ doses and effective doses were determined using a Monte Carlo program (PCXMC). There was considerable variation in examination protocols between different hospitals, indicating large variations in patient doses. Mean effective doses of different age groups ranged from 5 microSv to 14 microSv in skull and sinus examinations, from 25 microSv to 483 microSv in abdominal examinations, and from 6 microSv to 48 microSv in chest examinations. In chest and sinus examinations, the amount of data was extensive, allowing national pediatric diagnostic reference levels to be defined. Parameter selection in pediatric examination protocols should be harmonized in order to reduce patient doses and improve optimization.

In vivo dosimetry during DSA of the carotid and renal arteries. Deriviation of local DRLs

The Euratom directive 97/43 recommends the use of patient dose surveys in diagnostic radiology and the establishment of diagnostic reference dose levels (DRLs). The aims of this study are to perform measurements of the entrance surface dose (ESD) during diagnostic digital subtraction angiography (DSA) of the renal and carotid arteries using thermoluminescence dosemeters (TLDs), extraction of local DRLs, and calculation of the effective dose. Dose measurement for the staff was also performed. Dose measurements were performed on 48 participating patients. The mean effective dose was calculated to be 15.9 mSv and 8.9 mSv, for the renal and carotid DSA, respectively. The effective dose of the radiologist was calculated to be 0.022 mSv and 0.023 mSv per procedure for renal and carotid DSA respectively, when wearing a protective apron and using a movable ceiling mounted shield. Radiation dose variation depends on the physical characteristics of the patient, on the procedure preferences by radiologists and on the difficulties in conducting the procedures. The lack of DRLs for the specific examinations lead the research team to choose the DRL for DSA of the renal arteries to be 169 mGy for ESD at the pelvic region and for DSA of the carotid arteries to be 313 mGy for ESD at the region of the aortic arc.

Importance of Dose Settings in the X-Ray Systems Used for Interventional Radiology: A National Survey

The purpose of this work was to investigate the differences in dose settings among the X-ray units involved in a national survey of patient doses in interventional radiology (IR). The survey was promoted by the National Society of IR and involved 10 centers. As part of the agreed quality control for the survey, entrance doses were measured in a 20-cm-thick acrylic phantom simulating a medium-sized patient. A standard digital subtraction angiography (DSA) imaging protocol for the abdomen was used at the different centers. The center of the phantom was placed at the isocenter of the C-arm system during the measurements to simulate clinical conditions. Units with image intensifiers and flat detectors were involved in the survey. Entrance doses for low, medium, and high fluoroscopy modes and DSA acquisitions were measured for a field of view of 20 cm (or closest). A widespread range of entrance dose values was obtained: 4.5-18.6, 9.2-28.4, and 15.4-51.5 mGy/min in low, medium, and high fluoroscopy mode, respectively, and 0.7-5.0 mGy/DSA image. The ratios between the maximum and the minimum values measured (3-4 for fluoroscopy and 7 for DSA) suggest an important margin for optimization. The calibration factor for the dose-area product meter was also included in the survey and resulted in a mean value of 0.73, with a standard deviation of 0.07. It seems clear that the dose setting for the X-ray systems used in IR requires better criteria and approaches.

Radiation dose to patients and staff during angiography of the lower limbs. Derivation of local dose reference levels

Background The Euratom directive 97/43 recommends the use of patient dose surveys in diagnostic radiology and the establishment of reference dose levels (DRLs). Purpose To perform measurements of the dose delivered during diagnostic angiography of the lower limbs using thermoluminescence dosimeters (TLDs), extraction of DRLs and estimation of the effective dose and radiation risk for this particular examination. Methods Dose measurement was performed on 30 patients by using TLD sachets attached in 5 different positions not only on the patient, but also to the radiologist. All the appropriate factors were recorded. Measurement of the ESD was performed after each examination. Results The mean entrance skin dose (ESD) was calculated to be 70.8, 67.7, 24.3, 18.4, 9.7 mGy at the level of aorta bifurcation, pelvis, femur, knees, and at feet, respectively. The average effective dose is 9.8 mSv with the radiation risks for fatal cancer to be 5.4 × 10 −4. The effective dose of the radiologist was calculated to be 0.023 mSv per procedure. Conclusion Radiation dose variation depends on the physical characteristics of the patient, on the procedure preferences by radiologists and the difficulties in conducting procedures. The main reason for the increased patient dose, compared to other studies, is the number of frames rather than the duration of fluoroscopy. For DSA of the lower limbs, the DRL was chosen to be an entrance skin dose of 96.4 mGy in the pelvic region. The dose to the radiologist is negligible.

Trends in compressed breast thickness and radiation dose in breast screening mammography

An analysis was performed of the compressed breast thickness recorded in 146 mammographic patient dose surveys each consisting of 50 or more women carried out between 1993 and 2004. The results show a steady and statistically significant increase in compressed breast thickness with time, which is also present when individual independent screening centres and equipment manufacturers are compared. This increase seems most likely to be associated with an increase in the proportion of women in the breast screening age range classified as overweight and obese, which has occurred over the same time period. The associated trends in mean glandular dose per image were calculated for the mammography units used at the time of the surveys, using the most recently published conversion factors. The increase in average radiation dose that might have been expected as a result of the increase in average compressed breast thickness was not actually found in practice, possibly because of advances in equipment design and dose optimization strategies made during the 11-year period. Other implications of an increasing average compressed breast thickness are discussed.

Patient dose during radiological examination in the follow-up of bariatric surgery

A patient dose survey was carried out measuring the kerma-area product (KAP) values during radiological evaluation in the follow-up of bariatric surgery. The procedures were performed by three radiologists to adjust laparoscopic gastric bands and to detect postoperative complications after Roux-en-Y gastric bypass procedures to treat morbid obesity. Total fluoroscopy time, exposure factors and the overall contribution of fluoroscopy to the accumulated KAP value were recorded. The median KAP values were used to estimate organ doses and effective dose to a standard patient; the radiation risk associated with the procedures was also evaluated. The doses were smaller for one of the three radiologists, owing to a more appropriate beam collimation and a reduction of the screening time. The KAP values ranged from 1.6 to 7.1 Gy cm(2) for the laparoscopic adjustable gastric banding management, and from 3.0 and 8.3 Gy cm(2) for the radiological examinations after gastric bypass. As a whole, the effective doses associated to these procedures were between 0.5 and 2.7 mSv. The organs receiving the highest doses were not only breast, stomach, pancreas and liver, but also lungs, owing to of their high radiosensitivity, significantly contributed to the effective dose.

Experience of quality assurance across BUPA screening centres

BUPA's mammography quality assurance programme comprises an annual audit visit to 31 hospital-based screening centres by one of a team of three quality assurance mammographers. Clinical competence and mammographic film quality are assessed and technical quality control data are also collected. Monitoring of overall image quality is also addressed by a 'quarterly' test object film. A patient dose survey has been undertaken with exposure and breast thickness data collected from all sites. The standard of mammography across screening centres is good and well within NHSBSP standards. Reject rates are less than 3% and are personalised to each radiographer, enabling feedback and learning. Continuing professional development is in place and sites have evidence of a system of peer review. Quality control checks are undertaken according to recommended standards and records are kept. The mean glandular dose for a lateral oblique film across all centres was 1.7 mGy, well below the recommended national reference dose level. Mean doses at individual hospitals ranged from approximately 1.1 mGy to 2.3 mGy. Image quality scores using the Leeds TORMAM are generally satisfactory and typical of elsewhere, with only a few films having scores less than optimum and driving a move to higher contrast film/screens at these sites.