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Irish X-ray departments demonstrate varying levels of adherence to European guidelines on good radiographic technique

UCD School of Diagnostic Imaging, Herbert Avenue, Dublin 4, Ireland

	Abstract

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The Commission of European Communities (CEC) publication "European Guidelines on Quality Criteria for Diagnostic Radiographic Images" includes examples of good radiographic technique for a number of common X-ray examinations. If these guidelines are followed, compliance with dose and image quality criteria as specified in the CEC document should be demonstrated. Studies in England, Germany and Greece have shown that a number of X-ray departments are not using optimum techniques. The aim of this study is to demonstrate the level of adherence to CEC guidelines in Irish hospitals 3–4 years following publication of the above document. 16 hospitals were randomly chosen and the following details on technique and equipment were recorded for chest, abdomen, pelvis and lumbar spine examinations of standard sized patients: tube potential, focus-to-film distance, automatic exposure control (AEC), film–screen combination, X-ray tube filtration and secondary radiation grid. Varying levels of adherence to the guidelines were evident depending on the parameter being investigated, with no hospital demonstrating 100% compliance and no hospital demonstrating 100% non-compliance. For all parameters, with the exception of AEC use, the majority of hospitals exhibited non-adherence for at least one projection. The results suggest that if hospitals in Ireland observe the straightforward examples of good radiographic technique described in the CEC publication, significant reductions in collective dose can be achieved.

	Introduction

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The optimisation principle described in recent legislation [1] requires that each X-ray examination offers a net benefit to the patient. For such a benefit to exist, appropriate radiographic techniques must be employed, resulting in images with maximum diagnostic efficacy using the lowest possible radiation dose. To facilitate this, the Commission of European Communities (CEC) has issued guidelines identifying good technique for a range of common X-ray examinations that, if adhered to, should demonstrate good compliance with image and dose criteria [2, 3]. Although these CEC guidelines were officially published in 1996, a working document has been available since 1989 [4] and therefore it is interesting that a number of studies over the previous 9 years, in a variety of countries, have clearly demonstrated non-adherence to recommended techniques and equipment, particularly those relating to radiographic voltage, automatic exposure control (AEC) selection, focal-to-film distance (FFD), screen–film system and total filtration [5–11]. To promote the optimisation principle, it is important that X-ray departments in each European country examine their work practices to assess the level of adherence to CEC guidelines, to identify areas where less than optimal techniques exist and to implement recommendations. This is in the best interest of our patients.

The current study aims to record radiographic techniques employed in X-ray departments throughout Ireland for a number of common X-ray examinations. Variations in technique will be recorded, and compliance with CEC guidelines will be examined. The hospitals participating in this study have already performed a series of dose measurements and these results, along with proposed diagnostic reference levels, have been described in an earlier publication in this journal [12].

	Methodology

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All radiological departments in the Republic of Ireland were considered for inclusion in this study. A number were excluded on the basis that the adult examinations investigated (see below) were either not performed or were performed so infrequently that robust data could not be gathered during the period of this investigation. Of the remaining 38 hospitals, 16 were randomly selected, with all but one Health Board being represented, indicating a wide geographical distribution.

It was important that techniques representative of normal practice were recorded, so only examinations involving adults weighing within 13 kg of 70 kg were included, and the mean weight within each department was 70 kg±3 kg [2, 13]. The examinations chosen for this study were chest (posteroanterior), abdomen (anteroposterior (AP)), pelvis (AP) and lumbar spine (AP, lateral and lumbosacral (LSJ) junction). With the exception of the LSJ, a minimum of 10 patients were chosen for each projection within each hospital, resulting in a total of 884 examinations. Only 12 hospitals undertook the LSJ projection and the minimum number of patients for this projection was not always achieved.

To ensure that all relevant information was collected from each hospital, two forms were designed. The technique form recorded details relating to each individual examination and was completed by the radiographer responsible for the examination. The information provided by this form included location of examination (hospital and room number), examination type, exposure factors (tube potential (kVp), FFD, employment of AEC) and film–screen combination. The equipment form was completed by a superintendent radiographer and specifications relevant to the equipment within the examination room were outlined. This information included details on X-ray tube filtration and secondary radiation grid ratios.

	Results

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The data provided on the technique form (Table 1) showed that one hospital used a FFD of 90 cm, which was less than CEC recommendations for abdomen, pelvis and lumbar spine examinations, and that one other hospital failed to use AEC for the chest, abdomen and pelvis examinations. Two hospitals used a nominal film–screen speed of 200 for all examinations, whilst a further 13 hospitals used a speed of 400 for the LSJ projection. All these speeds were less than those suggested by the CEC.

View larger version (44K): [in this window] [in a new window]   Figure 1. Tube potential (kVp) selected for the posteroanterior chest projection across all hospitals compared with the Commission of European Communities recommendations (horizontal line).

View larger version (45K): [in this window] [in a new window]   Figure 2. Tube potential (kVp) selected for theanteroposterior abdomen projection across all hospitals compared with the Commission of European Communities recommendations (horizontal lines).

View larger version (39K): [in this window] [in a new window]   Figure 3. Tube potential (kVp) selected for theanteroposterior pelvis projection across all hospitals compared with the Commission of European Communities recommendations (horizontal lines).

View larger version (43K): [in this window] [in a new window]   Figure 4. Tube potential (kVp) selected for theanteroposterior lumbar spine projection across all hospitals compared with the Commission of EuropeanCommunities recommendations (horizontal lines).

View larger version (64K): [in this window] [in a new window]   Figure 5. Tube potential (kVp) selected for the lateral lumbar spine projection across all hospitals compared with the Commission of European Communities recommendations (horizontal lines).

View larger version (54K): [in this window] [in a new window]   Figure 6. Tube potential (kVp) selected for the lumbosacral junction projection across all hospitals compared with the Commission of European Communities recommendations (horizontal lines).

	Discussion

Top Abstract Introduction Methodology Results Discussion Conclusions References

 
Examples of good radiographic technique are presented in the CEC publication "European Guidelines On Quality Criteria For Diagnostic Radiographic Images" [2]. Although not intended as a definitive set of instructions, guidelines are provided that, if adhered to, should promote the optimization principle of producing images of good diagnostic efficacy at the lowest radiation dose. Previous studies have shown that adherence to CEC guidelines have led to reductions in effective dose by up to 50% with no change in image quality [3, 5].

Following examination of the techniques employed, namely FFD, AEC usage and choice of film–screen combination, hospitals showed varying levels of compliance with the CEC guidelines. Although only 1 hospital used a FFD of 90 cm for abdomen, pelvis and lumbar spine examinations, which is 10 cm less than the minimum level described in the CEC guidelines, 12 hospitals employed a FFD below the recommended distance of 115 cm for the same examinations, with 1 hospital below the recommended level for the chest projection. It is surprising that most departments are not employing optimum FFDs, since the direct relationship between shorter FFDs, higher patient doses and increased geometric unsharpness is well established [14–16]. The implementation of longer FFDs is a straightforward process and, with the exception of tube loading, which with modern X-ray tubes should be negligible, involves no additional expense.

Generally there was good adherence to the guidelines regarding AEC usage and nominal film–screen speed, with the exception being the LSJ where 13 out of a possible 14 hospitals did not use a sufficiently fast film–screen combination. The reason for this may be that departmental managers, although aware of the importance of a sensitive system for this relatively high dose projection [13], are unwilling to introduce a separate system for a single projection for financial reasons and the increased risk of system selection error. In addition, there is the practical problem of AECs being suitable for only one system speed. The Study Group on Quality Criteria Development of the European Commission may therefore wish to consider standardizing nominal system speeds for at least the lumbar spine examination, as projection-specific systems are probably unworkable.

The information provided by the equipment form demonstrated that, for all examinations, at least 50% of hospitals surveyed were using suboptimal secondary grid ratios and between 62% and 68% had lower than the recommended total filtration. Of the hospitals using inappropriate grids, only one had a lower grid ratio (8:1) than that recommended (10:1), whilst all but one of the remaining non-compliant hospitals used 12:1 ratio grids. One department used a grid with a 17:1 ratio. This means that since radiation dose is directly proportional to grid ratio, the majority of non-complying hospitals were delivering doses that were unnecessarily high. The potential for excess skin doses is also evident in the majority of hospitals using equipment with lower than recommended filtration levels [2, 17, 18]. It is of particular concern that three hospitals were using less than 2.5 mm Al equivalent total filtration, which is the minimum required under current national legislation [19].

Compliance with tube potential guidelines was inconsistent across different projections. For the two projections that provide the highest dose (lateral lumbar spine and LSJ), only three hospitals employed a tube potential below that recommended, and that was only for the lateral lumbar spine. Of the remaining projections (chest, abdomen, pelvis and AP lumbar spine) 9, 6, 12 and 8 hospitals, respectively, of the 16 surveyed used lower than optimal tube potential levels. The extent by which hospitals were below guided levels was greatest for the chest projection, with four hospitals employing tube potentials of more than 30 kVp below the recommended level of 125 kVp. The use of a high voltage technique for the chest has been calculated to reduce entrance surface dose by a half and effective dose equivalent by 20%, and therefore lower than appropriate tube potentials should not be selected [17, 20]. It is interesting to note that a small minority of hospitals were selecting higher than recommended tube potentials for certain examinations and, whilst this may be a good thing for reducing dose, the impact on image quality should be comprehensively assessed.

It should be acknowledged that in certain situations it may be difficult to adhere to all the CEC recommendations owing to equipment limitations. For example, focal properties of secondary radiation grids may limit the extent of increases in FFD; or tube output limits may prevent optimum levels of filtration being used. However, with grid tolerance limits of around 30% and with the excellent capabilities of most current X-ray units, difficulties in achieving the moderate CEC recommendations should be the exception rather than the rule.

Diagnostic reference levels at the 75th percentile for the aforementioned examinations have been calculated using data gathered from the hospitals surveyed in this study [9]. Although it is implicit from this that, for each projection, 25% of hospitals (4 from a possible 16) should aim to reduce their doses to below the reference level, the results from this study demonstrate the dose-reducing potential for all hospitals, since complete adherence to CEC criteria was not demonstrated in any hospital. In particular, departments should pay close attention wherever possible to FFDs, the use of appropriate grids and filtration, and optimum tube potentials. Complete compliance to CEC guidelines does, however, require a coordinated approach between radiographers and departmental managers, since certain parameters such as beam energy and FFD are obviously the responsibility of the person taking the X-ray, whilst changes to equipment or film type require the support of the budget holder.

The results from this work have been distributed to the participating centres and a follow-up study is being planned to assess the impact of this study's findings on practice.

	Conclusions

Top Abstract Introduction Methodology Results Discussion Conclusions References

 
Varying levels of compliance with the CEC guidelines on good radiographic technique were observed in 16 Irish hospitals for chest, abdomen, pelvis and lumbar spine X-ray examinations. All hospitals demonstrated non-adherence for at least one CEC recommendation, with no hospital demonstrating 100% non-compliance. Closer adherence to the CEC guidelines on FFD, secondary grid ratios, total filtration and tube potential would facilitate lower patient radiation dose at minimal cost or inconvenience. Recommendations by the CEC on varying nominal film–screen combination speeds for lumbar spine examinations should be revisited.

	Acknowledgments

 
The authors would like to thank Dr Michael Casey and Dr Paul Shrimpton for their guidance and help throughout this study.

Received for publication April 20, 2001. Revision received August 29, 2001. Accepted for publication August 31, 2001.

	References

Top Abstract Introduction Methodology Results Discussion Conclusions References

 

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