Suggested diagnostic reference levels for paediatric X-ray examinations in India

Exposure of children to ionising radiation is considered to carry higher risk than that of adults; therefore a need to suggest diagnostic reference levels (DRLs) for the common paediatric diagnostic X-ray procedures was recognised for the X-ray machines meeting the requirements of the recently implemented Safety Code for Medical Diagnostic X-ray Equipment and Installations in India. Measurements were carried out for entrance surface air kerma (free in air) in conventional paediatric X-ray diagnostic examinations among four age groups: <1, 1-4, 5-9 and 10-15 y. A total of 2240 air kerma measurements at different fixed focus to skin distances were studied for 7 paediatric diagnostic examinations with 11 different projections on 62 X-ray machines installed in 22 selected hospitals in the country. The third quartile values of air kerma per paediatric examination for the age group of 5-9 y were considered as values of paediatric DRLs. The suggested values of DRLs are 0.2 mGy for chest AP/PA, 0.3 mGy for chest LAT, 0.7 mGy for lumber spine AP, 1.3 mGy for lumber spine LAT, 0.3 mGy for thoracic spine AP, 0.6 mGy for thoracic spine LAT, 0.5 mGy for abdomen AP, 0.7 mGy for pelvis AP, 0.6 mGy for skull PA, 0.5 mGy for skull LAT and 0.8 mGy for hip joints AP.     

Entrance surface dose and image quality: comparison of adult chest and abdominal X-ray examinations in general practitioner clinics, public and private hospitals in Malaysia

This study was undertaken to compare the entrance surface dose(ESD) and image quality of adult chest and abdominal X-ray examinationsconducted at general practitioner (GP) clinics, and public andprivate hospitals in Malaysia. The surveyed facilities wererandomly selected within a given category (28 GP clinics, 20public hospitals and 15 private hospitals). Only departmentalX-ray units were involved in the survey. Chest examinationswere done at all facilities, while only hospitals performedabdominal examinations. This study used the x-ray attenuationphantoms and protocols developed for the Nationwide Evaluationof X-ray Trends (NEXT) survey program in the United States.The ESD was calculated from measurements of exposure and clinicalgeometry. An image quality test tool was used to evaluate thelow-contrast detectability and high-contrast detail performanceunder typical clinical conditions. The median ESD value forthe adult chest X-ray examination was the highest (0.25 mGy)at GP clinics, followed by private hospitals (0.22 mGy) andpublic hospitals (0.17 mGy). The median ESD for the adult abdominalX-ray examination at public hospitals (3.35 mGy) was higherthan that for private hospitals (2.81 mGy). Results of imagequality assessment for the chest X-ray examination show thatall facility types have a similar median spatial resolutionand low-contrast detectability. For the abdominal X-ray examination,public hospitals have a similar median spatial resolution butlarger low-contrast detectability compared with private hospitals.The results of this survey clearly show that there is room forfurther improvement in performing chest and abdominal X-rayexaminations in Malaysia.     

Patient dose in digital projection radiography

In projection radiography, two types of digital imaging systems are currently available, computed radiography (CR) and direct radiography (DR): a difference between them can be stated in terms of dose and image quality. In the Radiology Emergency Department of our hospital, a flat-panel DR equipment (Siemens Axiom Aristos FX) and two CR systems (Kodak CR-850) are employed. In 2006, five standard radiographic examinations (abdomen, chest, lumbar spine, pelvis, skull) were considered: doses delivered to patients in terms of both entrance skin dose (ESD) and effective dose (E) were calculated and compared in order to study the dosimetric discrepancies between CR and DR. Assessment of image quality is undertaken by Consultant Radiologists to ensure that the quality criteria for diagnostic radiographic images of the European guidelines were met. Results showed that both ESD and E in DR are lower than that in CR; all images met the criteria in the European Guidelines for both modalities and were used for reporting by the radiologists. Since the operators are the same and the image quality is comparable in both modalities, this study shows that in the considered examinations, DR can perform better than CR from a dosimetric point of view.     

Radiation dose optimisation and risk estimation to patients and staff during hysterosalpingography

Hysterosalpingography (HSG) is an efficient radiological examination for the evaluation of the female reproductive tract. However, it involves unavoidable irradiation to the ovaries of women in childbearing age. Therefore, radiation dose optimisation is required in order to reduce the probability of the associated risks. This study attempts to: measure patient and staff doses, estimate the effective dose and radiation risk for HSG using digital fluoroscopic images. Thirty-seven patients with infertility were examined using two digital X-ray machines. Thermoluminescence dosimeters (TLD) were used to measure entrance surface dose (ESD) for patients and staff during the procedure. The mean ESD and thyroid surface dose of the patient were 3.60 and 0.17 mGy, respectively, while the mean ESD for the staff was 0.18 mGy per procedure. The patient overall risk for cancer and hereditary effects is 24 x 10(-6), while the risk for the staff is negligible. HSG with fluoroscopic technique demonstrate improved dose characteristics, compared to the conventional radiographic-based technique, reducing the surface dose by a factor of 3, without compromising the diagnostic findings.     

Entrance surface doses to patients undergoing selected diagnostic X-ray examinations in Sudan

The aim of the study was to evaluate the entrance surface doses (ESDs) to patients undergoing selected diagnostic X-ray examinations in major Sudanese hospitals. ESD per examination was estimated from X-ray tube output parameters in four hospitals comprising eight X-ray units and a sample of 346 radiographs. Hospital mean ESDs estimated range from 0.17 to 0.27 mGy for chest AP, 1.04-2.26 mGy for Skull AP/PA, 0.83-1.32 mGy for Skull LAT, 1.31-1.89 mGy for Pelvis AP, 1.46-3.33 mGy for Lumbar Spine AP and 2.9-9.9 mGy for Lumbar Spine LAT. With exception of chest PA examination at two hospitals, mean ESDs were found to be within the established international reference doses. The results are useful to national and professional organisations and can be used as a baseline upon which future dose measurements may be compared.     

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.     

Entrances skin dose distribution maps for interventional neuroradiological procedures: a preliminary study

Dose estimation in interventional neuroradiology can be useful to limit skin radiation injuries. The purpose of this study was to evaluate the role of entrance skin dose (ESD) maps in planning exposure condition optimisation. Thirteen cerebral angiography and five embolisation procedures were monitored, measuring ESD, dose-area product (DAP) and other operational parameters. A transmission ionisation chamber, simultaneously measuring air kerma and DAP, measured dose-related quantities. Data acquisition software collected dosimetric and geometrical data during the interventional procedure and provided a distribution map of ESD on a standard phantom digital image, with maximum value estimation. Values of 88-1710 mGy for maximum skin dose and 16.7-343 Gy cm2 for DAP were found. These data confirm the possibility of deterministic effects during therapeutic interventional neuroradiological procedures like cerebral embolisation. ESD maps are useful to retrospectively study the exposure characteristics of a procedure and plan patient exposure optimisation.     

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.     

Radiation doses from some common paediatric X-ray examinations in Sudan

Radiation doses to patients from some common paediatric X-ray examinations were studied in three hospitals in Khartoum state, Sudan. Entrance surface dose (ESD) was determined from exposure settings using DosCal software. Totally, 459 patients were included in this study. Mean ESDs obtained from anteroposterior projection for chest, skull, abdomen and pelvis for neonates falls in the range of 52-100, 115-169, 145-183, 204-242 microGy, respectively. For a 1-y-old infant, mean ESD range was 80-114, 153-202, 204-209, 181-264 microGy, respectively. Some doses for neonates and infants were exceeding the reference doses by >20%. The results highlighted that a good technique has to adhere to guidelines necessarily. As demonstrated elsewhere, patients' doses were high in departments using single-phase generators compared with those using constant potential. The results presented will serve as a baseline data needed for deriving reference doses for paediatric X-ray examinations in Sudan.     

An overview of doses to patients and irradiation conditions of diagnostic chest x ray examinations carried out in hospitals of the City of São Paulo,Brazil

Recently the Brazilian health organisation published information conceming the number of hospitals, details of radiological equipment and frequency of medical examinations in the country. The information concerning the city of S?o Paulo is compiled here, complemented by a survey of absorbed doses to patients undergoing the most frequent examination: chest radiographs (postero-anterior (PA) and lateral (LAT) projections), as well as the physical parameters employed (tube voltage, current-time product, focus-film distance, field size). To collect the data, a sample of 12 hospitals (a representative sample of the 199 located in the city) was chosen, totalling 27 X ray machines. An anthropomorphic phantom was irradiated to simulate the patient. Absorbed doses were determined with thermoluminescence dosemeters placed in the phantom, externally and internally. Mean values of entrance surface dose (ESD) for PA and LAT projections were 0.22 mGy (from 0.07 to 0.61 mGy) and 0.98 mGy (from (1.30 to 4.01 mGy), respectively. The average organ doses per complete examination (PA and LAT) were 0.15 and 0.24 mGy to thyroid and lung, respectively. The thyroid was thus in the primary beam in many cases. The large variation in the ESD and organ doses indicates that much can be done in order to reduce the patient doses by adequate changes of physical parameters, without loss of image quality.     

Simulation studies on a prototype ionisation chamber for measurement of personal dose equivalent, Hp(10)

A prototype ionisation chamber for direct measurement of the personal dose equivalent, Hp(10), similar to the one developed by the Physikalisch-Technische Bundesantalt (PTB), was designed and constructed by the Metrological Laboratory of Ionizing Radiation (LMRI) of Nuclear and Technological Institute (ITN). Tests already performed have shown that the behaviour of this chamber is very similar to the PTB chamber, mainly the energy dependence for the X-ray radiation qualities of the ISO 4037-1 narrow series N-30, N-40, N-60, N-80, N-100 and N-120 and also for gamma radiation of 137Cs and 60Co. However, the results obtained also show a dependence on the energy and angles of incident radiation and a low magnitude of the electrical response of the ionisation chamber. In order to optimise the performance of the chamber, the LMRI initiated numerical simulation of this ionisation chamber by Monte Carlo method using the MCNPX code.     

Patient dose in neonatal units

Lung disease represents one of the most life-threatening conditions in prematurely born children. In the evaluation of the neonatal chest, the primary and most important diagnostic study is therefore the chest radiograph. Since prematurely born children are very sensitive to radiation, those radiographs may lead to a significant radiation detriment. Hence, knowledge of the patient dose is necessary to justify the exposures. A study to assess the patient doses was started at the neonatal intensive care unit (NICU) of the University Hospital in Leuven. Between September 2004 and September 2005, prematurely born babies underwent on average 10 X-ray examinations in the NICU. In this sample, the maximum was 78 X-ray examinations. For chest radiographs, the median entrance skin dose was 34 microGy and the median dose area product was 7.1 mGy.cm(2). By means of conversion coefficients, the measured values were converted to organ doses. Organ doses were calculated for three different weight classes: extremely low birth weight infants (<1000 g), low birth weight infants (1000-2500 g) and normal birth weight infants (>2500 g). The doses to the lungs for a single chest radiograph for infants with extremely low birth weights, low birth weights and normal birth weights were 24, 25 and 32 microGy, respectively.     

Patient dose, image quality and radiographic techniques for common X ray examinations in two Greek hospitals and comparison with European guidelines

The radiographic technique factors and the quality of each radiographic image for three common examinations (chest PA, pelvis AP and lumbar spine LAT) were compared with the European criteria and entrance surface dose (ESD) was measured for each radiograph in two Greek hospitals. The measurements were carried out using calibrated LiF thermoluminescence dosemeters. The patients were selected so that their weight was close to 70 +/- 10 kg and their height to 170 +/- 10 cm. Effective dose values were calculated using a PC-based Monte Carlo program. All four X ray rooms in the survey achieved mean doses well below the European reference doses. However the mean doses in the X ray rooms differed by a factor of about 3.     

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.     

Comparison of entrance surface doses of some X ray examinations with CEC reference doses

Entrance surface dose (ESD) measurements have been carried out in Nigeria as part of the ongoing dose reduction programme. Thermoluminescence dosemeters (TLD) were used to measure skin entrance doses for four common radiographic views in three hospitals. The mean ESD for the PA chest examination in all the participating hospitals was in the range 0.12 - 4.46 mGy. The mean ESD for the AP skull. PA skull and LAT skull were 8.55, 5.17 and 6.97 mGy respectively. The mean ESD values are greater than the CEC reference doses, except for rooms 1 and 2 in UCH where the entrance surface doses for PA chest examination are below the CEC reference dose. The QA test results show non-compliance of the accuracy of tube voltage with acceptance limit in three rooms. The timer accuracy is also not within the acceptance limit in two rooms. The reproducibility of both the kVp and timer in all the rooms is good.     

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.     

Estimation of radiation doses to patients and surgeons from various fluoroscopically guided orthopaedic surgeries

In this study, a mathematical method was used to estimate the entrance surface dose (ESD) to the patient and the scattered dose (Ds) to the operating surgeon during various fluoroscopically guided surgical orthopaedic procedures. For 204 patients, the procedure type, the fluoroscopy time and the highest tube potential and current values observed during fluoroscopy were recorded. For the most often performed procedures (intramedullary nailing of peritrochanteric fractures, open reduction and internal fixation of malleolar fractures and intramedullary nailing of diaphyseal fractures of the femur), the respective mean fluoroscopy times were 3.2, 1.5 and 6.3 min while the estimated mean ESDs were 183, 21 and 331 mGy, respectively. The estimated Ds rates for the hands, chest, thyroid, eyes, gonads and legs of the operating surgeon were on average to 0.103, 0.023, 0.013, 0.012, 0.066 and 0.045 mGy min(-1), respectively, and compare well with the literature. The mathematical estimation of doses cannot replace actual measurements; however, it can be used for a preliminary assessment of the radiation dose levels during various surgical procedures, so that the operator, the surgeon and the rest of the medical staff involved could be aware of the associated radiation risk and the radiation protection measures required.     

Optimisation of image plate radiography with respect to tube voltage

PURPOSE: To find the tube voltage that results in the highest image quality per effective dose unit for chest and pelvis radiography, respectively, using image plates. METHODS: Two anthropomorphic phantoms (chest and pelvis) were imaged with several different tube voltages. The mA s settings were chosen so that the effective dose to the phantom was the same, regardless of the tube voltage, for the two examinations, respectively. The quality of the images was evaluated by six experienced radiologists using visual grading analysis. RESULTS: For both the chest and the pelvis examinations, the image quality increased when the tube voltage was reduced compared with the standard settings (125 and 70 kV for chest and pelvis, respectively), which were used for screen-film radiography previously. CONCLUSIONS: The image quality of image plate radiography can be increased by lowering the tube voltage compared with the one that was used for screen-film radiography.     

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).