Factors influencing patient radiation doses from barium enema examinations

PURPOSE: To analyse factors behind the variation of patient doses from barium enema (BE) examinations. MATERIAL AND METHODS: The patients' (n=89) organ and effective doses (E) due to BE examinations were computed with the ODS-60 program. An average risk factor for BE examinations was derived using the BEIR V schema. The correlation of E with several independent variables was analysed. RESULTS: Median Es at five hospitals were 4.4, 6.1, 7.1, 13 and 16 mSv. The E of the female patients (median 9.2 mSv) was higher than that of the males (median 5.4 mSv) (p<0.001) due to the higher female doses to the gonads, bladder and uterus, resulting from different body structure. An average fatal risk factor of 0.02%. per one BE examination was derived. Factors controlled by the radiologist (screening time, number of exposures) explained 40% and patient-related factors explained 16% of the total variation of E. The equipment-related factors are included in the residual 44%. CONCLUSION: Due to the large contribution of the radiologists' examination technique in the value of E, an optimal examination technique is essential in reducing doses and the stochastic risk to patients.     

Patient and occupational dosimetry in double contrast barium enema examinations

A new and relatively simple method is presented to distribute total dose-area product (DAP) over a number of projections that model exposure during double contrast barium enema (DCBE) examinations. In addition, hitherto unavailable entrance and effective doses to the physician performing the DCBE examination have been determined. DAP, fluoroscopy time, number of images as well as some patient data were collected for 150 DCBE examinations. For a subset of 50 examinations, the distribution of DAP over 12 hypothetical but representative projections was estimated by measuring the entrance dose in the centre of each of these projections during the complete procedure. Effective dose to the patient was obtained using DAP to effective dose conversion coefficients calculated for each of the 12 projections. Exposure of the worker was quantified by measuring the entrance dose at the forehead, neck, arms, right hand and legs. The sex-averaged effective dose to the patient per examination was 6.4+/-2.1 mSv (mean+/-SD; n=50) and the corresponding DAP was 44+/-22 Gy cm(2). The effective dose to the worker per examination was 0.52 microGy (n=50), whereas the highest entrance dose of 30+/-25 microGy was found for the right arm. The proposed method for deriving the distribution of total DAP over a set of representative projections is much less time consuming than visual observation of patient exposure, whilst accuracy seems acceptable. Entrance and effective doses per examination for workers in DCBE examinations are very low. For a normal workload, doses remain far below the legally established dose limits.     

Patient doses from barium meal and barium enema examinations and potential for reduction through proper set-up of equipment.

Patient doses for barium meal and barium enema examinations, performed at two Greek hospitals, were measured using a dose-area product meter. The results were analysed to obtain the contributions of fluoroscopy and radiography to the dose as well as a number of other dose related parameters for each examination. The doses observed are within the range of values reported by other authors and comply with the dose reference levels (DRLs), proposed from relevant surveys in the UK and The Netherlands. However, comparison between the two hospitals revealed significant differences in the contributions to dose from the various parts of the examinations. To determine the reasons for these differences, measurements of dose related parameters were made using a Plexiglas phantom and standard clinical X-ray machine settings. Factors contributing to increased dose delivery were determined and recommendations have been made concerning ways in which doses might be reduced in each hospital, without degradation of the diagnostic quality of these examinations.     

Radiation doses for barium enema and barium meal examinations in Ireland: potential diagnostic reference levels

Wide variations in patient dose for the same examinations have been demonstrated by several studies throughout Europe. By investigating patient dose, variations can be acknowledged, causal agents sought and the necessary adjustments made. Diagnostic reference levels (DRLs) provide a framework with which dose levels from individual hospitals are compared, and when exceeded, corrective actions can be taken where appropriate. This study aimed to establish DRLs for barium enema and barium meal examinations in Ireland. Measurements were recorded using a dose-area product meter in 12 hospitals representing 33% of relevant hospitals. Results demonstrated wide mean hospital dose variation, by up to a factor of 7.8 and 4.2 for barium enema and barium meal examinations, respectively. Minimum and maximum individual patient dose values varied by a factor of 45 for barium enemas and 90 for barium meal examinations. Reasons for dose variations were complex, but major factors for both examinations were fluoroscopy time, secondary radiation grid type and level of filtration. Some examination-specific factors were also noted. DRLs, established using the quantity dose-area product, were calculated to be 47 Gy cm(2) for barium enemas and 17 Gy cm(2) for barium meal examinations. Although the DRL value for barium meals was the same as the reference value established in the UK for that examination in 1996, the barium enema DRL in this study was 45% higher than the relevant UK value.     

Compensation filtration in paediatric double contrast barium enema examinations

A prospective study of double contrast barium enema examinations performed on 42 children aged 2.5-19 years (mean age 12.3 years) showed that compensation filtration improved the radiographic quality in 32 (76%) of the examinations; it also reduced radiation dosage in all patients. In no examination was the use of a filter deleterious. Compensation filtration is recommended for all paediatric double contrast barium enema examinations to improve radiographic quality and reduce radiation dosage.     

Reduction of radiation dose to patients undergoing barium enema by dose audit.

Nowadays, new fluoroscopic machines are usually equipped with a dose-area product (DAP) meter for dose measurement. In our hospital, DAP meters have been used in the Diagnostic Radiology Department for dose audit since June 1997. Demographic patient data, name of radiologist, fluoroscopic duration and DAP readings of every case were recorded by radiographers. In early 1999, questionnaires were distributed to radiologists who had performed fluoroscopic examinations during the auditing period. 23 radiologists with varying years of experience completed the questionnaire and their practice was analysed. Since familiarization with the examination technique would affect radiologists' practice, these radiologists were divided into two groups for analysis. Radiologists with less than 3 years of experience were grouped together as junior radiologists, whilst others were grouped as senior radiologists. Results of the questionnaire indicated that radiologists generally found DAP meters useful for dose evaluation in the process of technique refinement. Radiologists aware of being under continuous surveillance of their practice showed significant reduction of doses (junior radiologists 25%, p<0.005; senior radiologists 36%, p<0.05) and fluoroscopic times (junior radiologists 36%, p<0.001; senior radiologists 18%, p<0.05) compared with radiologists who were unaware that they were under surveillance but with similar radiological experience. This effect is believed to be because of increased awareness of radiation dose through audit. In addition, this "audit effect" may also affect junior radiologists in decision-making regarding the number of radiographs (p<0.05), but no effect was found for senior radiologists (p>0.5).     

Patient doses from CT examinations in Turkey

PURPOSE

We aimed to establish the first diagnostic reference levels (DRLs) for computed tomography (CT) examinations in adult and pediatric patients in Turkey and compare these with international DRLs.

METHODS

CT performance information and examination parameters (for head, chest, high-resolution CT of the chest [HRCT-chest], abdominal, and pelvic protocols) from 1607 hospitals were collected via a survey. Dose length products and effective doses for standard patient sizes were calculated from the reported volume CT dose index (CTDI_vol).

RESULTS

The median number of protocols reported from the 167 responding hospitals (10% response rate) was 102 across five different age groups. Third quartile CTDI_vol values for adult pelvic and all pediatric body protocols were higher than the European Commission standards but were comparable to studies conducted in other countries.

CONCLUSION

The radiation dose indicators for adult patients were similar to those reported in the literature, except for those associated with head protocols. CT protocol optimization is necessary for adult head and pediatric chest, HRCT-chest, abdominal, and pelvic protocols. The findings from this study are recommended for use as national DRLs in Turkey.Computed tomography (CT) scanners have been used in diagnostic radiology since the early 1970s and have gained popularity worldwide owing to their substantial and life-saving clinical benefits. However, the increase in the use of CT applications has led to the emergence of radiologic concerns, such as cancer risk, because of the incremental collective effective dose (ED) associated with its use. Even if the number of CT exams is small among all radiography procedures, a large proportion of medical radiation exposure comes from CT applications. CT contributes the biggest part of radiation from medical sources in the United States (~66%), United Kingdom (~47%), and Germany (~60%) (1, 2). Owing to these concerns, protection of patients of all age groups from the effects of unnecessary and harmful radiation has become a priority in CT examinations (1–3).Dose constraint is one of the fundamental radiation protection principles; however, this cannot be applied in radiologic examinations (3). Therefore, the optimization principle has become increasingly important and needs to be performed with considerable attention in medical practice. Comparison of CT application parameters and patient radiation doses with diagnostic reference levels (DRLs) is a recommended method often considered the first step for optimization in CT examinations (4). Medical practitioners utilize national DRLs as an indicator of dose, in accordance with hospital CT protocols. When patient doses exceed the national DRL, CT examinations should be re-evaluated and optimized (5). The establishment of DRLs for individual countries has been recommended by international organizations such as the International Commission on Radiological Protection (ICRP) and the European Commission (EC) (6–8).The justification of CT examinations may necessitate the willingness of radiology personnel to participate in decision-making regarding the use of radiographic examinations; however, more important input may be derived from the optimization of scanning protocols. Patient radiation doses originating from radiologic examinations can exhibit large variations, even when they are performed in the same hospital department (9, 10). The existence of DRLs for specific radiologic examinations enables standardization across the majority of patients. However, DRLs are neither realistic boundaries for CT technicians nor are they regarded as an indicator of good medical practice. Determination of actual dose levels for targeted patient groups and attempts to maintain radiation exposure below the DRLs may reduce the detrimental health effects associated with radiologic procedures (11, 12).A recent study performed in Turkey investigated patients who underwent CT examinations while pregnant, unbeknownst to the patient and technicians. Mean patient radiation doses from abdominal CT examinations were reported to be approximately three-fold higher than those published in the literature (13). Therefore, there is an urgent need for establishment of national DRLs and for the optimization of CT scanning protocols. In 2012, there were more than 1600 CT devices used in Turkey and a technical report from the country’s national authority revealed that there is insufficient information concerning radiation doses from CT devices (14).     

Effect of glucagon on the diagnostic accuracy of double-contrast barium enema examinations

The effect of glucagon-induced hypotonicity on the diagnostic accuracy of double-contrast barium enema examinations was determined in 133 consecutive patients in a double-blind crossover study. All patients underwent colonoscopy and served as their own controls by undergoing a double-contrast study after intravenous injection of 1 mg of glucagon and another after intravenous injection of 1 ml of saline placebo, in randomized order. The frequencies of good/excellent hypotonicity and quality of examinations after first doses of glucagon (55.3% and 80.8%) were not significantly different from the frequencies of good/excellent results after first doses of saline (51.3% and 86.5%). The sensitivity was 72.6% after glucagon and 64.5% after placebo; the specificity was 88.7% after glucagon and 77.9% after placebo; and the respective accuracies were 81.2% and 71.9%. These percentages should be used only to compare results with and without glucagon and, by study design, do not represent results of a complete double-contrast study. The variation among these percentages was not statistically significant, but diverticulitis was more accurately diagnosed after glucagon. It was concluded that glucagon does not significantly improve the sensitivity and specificity of the double-contrast barium enema examination and should be used only in selected instances.     

A comparison of fluoroscopy time and dose area product (DAP) readings for outpatient barium enema examinations

Historically, the radiologist was the operator for the barium enema examination. However, as a result of the worldwide shortage of radiologists, and the development of the four-tier service delivery model, radiographers at this Trust have undertaken postgraduate training, and now perform and report their own barium enema examinations. Periodic clinical audit is required to ensure that the patient receives the same high standard of care, in terms of radiation dose, irrespective of the health care professional undertaking the examination. This study seeks to assess the situation at this large hospital in East Anglia. Fluoroscopy time and dose area product (DAP) measurements from 92 barium enema examinations, performed by radiographers (90.2%) and radiologists (9.8%), were compared to see if there were significant differences in the radiation dose to the patient, as a result of the operator group undertaking the examination. The study shows that although radiographers produce more undercouch images (a mean of 12.1 images compared to 9.3 images), their fluoroscopy times (a mean of 1.74 min compared with 2.82 min) and undercouch DAP readings (a mean of 1244.9 cGycm² compared with 1971.3 cGycm²) were lower than that of the radiologists. This resulted in a lower total DAP (a mean of 1536.8 cGycm² compared with 2236.0 cGycm²), and therefore a lower radiation dose to the patient, when the examination was undertaken by a radiographer, as opposed to a radiologist. The researchers believe that this study highlights the ability of the radiographer to assume the role of the operator for the barium enema examination. Nevertheless, it is acknowledged that continued assessment is required to ensure that performance is maintained.     

Patient dose considerations in computed tomography examinations

Ionizing radiation is extensively used in medicine and its contribution to both diagnosis and therapy is undisputable. However, the use of ionizing radiation also involves a certain risk since it may cause damage to tissues and organs and trigger carcinogenesis. Computed tomography (CT) is currently one of the major contributors to the collective population radiation dose both because it is a relatively high dose examination and an increasing number of people are subjected to CT examinations many times during their lifetime. The evolution of CT scanner technology has greatly increased the clinical applications of CT and its availability throughout the world and made it a routine rather than a specialized examination. With the modern multislice CT scanners, fast volume scanning of the whole human body within less than 1 min is now feasible. Two dimensional images of superb quality can be reconstructed in every possible plane with respect to the patient axis (e.g. axial, sagital and coronal). Furthermore, three-dimensional images of all anatomic structures and organs can be produced with only minimal additional effort (e.g. skeleton, tracheobronchial tree, gastrointestinal system and cardiovascular system). All these applications, which are diagnostically valuable, also involve a significant radiation risk. Therefore, all medical professionals involved with CT, either as referring or examining medical doctors must be aware of the risks involved before they decide to prescribe or perform CT examinations. Ultimately, the final decision concerning justification for a prescribed CT examination lies upon the radiologist. In this paper, we summarize the basic information concerning the detrimental effects of ionizing radiation, as well as the CT dosimetry background. Furthermore, after a brief summary of the evolution of CT scanning, the current CT scanner technology and its special features with respect to patient doses are given in detail. Some numerical data is also given in order to comprehend the magnitude of the potential radiation risk involved in comparison with risk from exposure to natural background radiation levels.     

Electrical stimulation for anal sphincter control in barium enema examinations: an extended trial.

The routine use in 500 consecutive patients of a barium enema cannula incorporating stimulating electrodes is described. Barium retention was improved by the electrically maintained contraction of the anal sphincter. The cannula was connected to a battery-powered control unit which provided the stimulus; pulse width was 1 msec and frequency was 20 pulses/sec. The pulse amplitude, adjusted for each patient, was in the range of 5--17V. A standard procedure was adopted throughout the trial without the use of colonic relaxants (such as anticholinergic drugs). The barium suspension and water were in stilled at body temperature. A comparison with a control series of 200 patients showed a significant reduction in the failure rate from 20% to 4%. No unpleasant side effects were encountered apart from a tingling sensation in the anal region which was expected. The principal factors contributing to failure were fecal impaction and diverticular disease.     

Linear shadows in the air-contrast barium enema

In 3 patients with carcinoma of the colon, lesions were seen as linear shadows on air-contrast barium enema studies. When the elevation of a lesion is slight or the tumor--mucosal interface is gently sloping, the tumor's proximal and distal edges may be ill-defined or disappear altogether. Thus only a linear shadow representing the interface between the tumor surface and air in the lumen appears. Other causes of these lines are also discussed.     

Dose-area product readings for fluoroscopic and plain film examinations, including an analysis of the source of variation for barium enema examinations

This paper contains the results of an investigation undertaken between 1994 and 1996 using dose-area product (DAP) meters for monitoring radiation doses from six types of simple examinations and seven types of complex examinations. Mean hospital DAP levels have been compared with National Reference Levels (NRL), with most departments producing levels lower than NRLs. DAP readings have allowed the proposal of provisional Reference Levels (RL) to be set for simple and complex examinations. The results were also compared with recently published data from the National Radiological Protection Board (NRPB), highlighting those hospitals which need to make changes in radiographic technique. The study of DAP reference doses also confirms that dose levels for complex investigations are clearly related to technique, in terms of screening time and number of films. Although the use of increased screening tube kilovoltage may be relevant, the overall effect is small. The results suggest that there is still a need to optimize the protocols for these examinations. The use of digital equipment has been shown to have a complex effect on dose, particularly in the case of investigations involving both films and fluoroscopy.