a Dental Accident and Emergency Department and the implications for patient dose. ... Incidental findings that might alter patient management were also noted.
ã
Dentomaxillofacial Radiology (2001) 30, 260 ± 263 2001 Nature Publishing Group. All rights reserved 0250 ± 832X/01 $15.00 www.nature.com/dmfr
The use of panoramic radiography in a dental accident and emergency department J Sewell*,1, N Drage1 and J Brown1 1
Department of Dental Radiology, Guy's King's and St Thomas's Dental Institute, London, UK
Objectives: To determine the rate of appropriate requests for panoramic radiography (PR) in a Dental Accident and Emergency Department and the implications for patient dose. Methods: Two hundred and seventy-one requests for PR during July 1998 were assessed by two dental radiologists and categorised as appropriate or inappropriate based on established selection criteria. Incidental ®ndings that might alter patient management were also noted. Results: One hundred and ®fty-seven requests (58%) were considered appropriate and 114 (42%) inappropriate. The most common inappropriate request was to assess disease localised to one or two teeth. Dental students were involved in 186 requests and 76 of these (41%) were inappropriate. The estimated saving in collective radiation dose over the month of the study if appropriate radiographs had been taken, would have been approximately 540 mSv, a reduction of 70%. Three out of 114 (3%) inappropriate, PRS showed minor incidental ®ndings. Conclusions: A considerable proportion of requests for PR were inappropriate. In most of these cases, periapical radiographs would have provided more detail with less radiation dose. The large number of inappropriate requests involving dental students has implications for educators. The use of local selection criteria based on currently accepted guidelines would have reduced the dose substantially. Keywords: radiography, panoramic; radiation dosage; decision making; diagnostic radiology
Introduction Panoramic radiography (PR) is a simple, quick technique for demonstrating all the teeth and their supporting structures on one radiograph with a relatively low radiation dose. Compared with a full mouth set of periapical radiographs (FMS), it is less time consuming, more comfortable for the patient, and involves considerably less radiation.1 Its use in general dental practice in the UK has increased more rapidly than intra-oral radiography over the past 15 years.2 However, the PR has major limitations. Only those structures within the focal trough are clearly seen while air spaces, soft tissues, and ghost images can be projected over the regions of interest. There is also an inherent loss of image quality associated with the use of a screen/®lm combination compared with intra-
*Correspondence to: J Sewell, Department of Dental Radiology, Floor 23 Guy's Tower, Guy's Hospital, London SE1 9RT, UK Received 17 January 2001; accepted 14 May 2001
oral ®lm.3,4 Although image quality has improved with newer equipment, the authors of the recent document on selection criteria maintained that it was still inferior to intra-oral radiography.5 Rushton and Horner4 in their review of the literature concluded that PR was less accurate than intra-oral radiography for the most common dental conditions, caries, and periodontal and periapical diseases. Moreover, they also questioned its use for screening since for a large proportion of patients, it is of questionable accuracy where disease is detected, and of no consequence to patient management when asymptomatic anomalies are found. Selection Criteria for Dental Radiography5 made recommendations for the use of PR in order to reduce the number of unnecessary examinations in general dental practice. The appropriateness of requests for PR from a Dental Accident and Emergency (DA&E) department in a United Kingdom dental school is unknown and has implications for student education as well as patient care.
Panoramic radiography J Sewell et al
This study was therefore undertaken to determine the rate of inappropriate requests for PR from a DA&E department, the clinical conditions under investigation, the degree of student involvement in the decision-making, the potential dose reduction if guidelines were used and the possible failure to detect signi®cant clinical conditions. Methods Ethical committee approval was obtained for this study. All patients referred from DA&E for PR during July 1998 were included (n=271). The casenotes and radiographs were examined by two dental radiologists independently to determine the appropriateness of the request. Appropriate selection criteria were modi®ed from those of the Faculty of General Dental Practitioners.5 It was not anticipated that DA&E would request PR for orthodontic, full periodontal or restorative assessments. A request was considered appropriate in the following clinical situations: . . .
. . .
suspected fracture of the mandible; assessment of third molars; TMJ problems where there was recent trauma, signi®cant dysfunction or change in range of movement, sensory or motor alteration or significant changes in occlusion; underlying bone disease indicated by clinical examination; prior to multiple extractions; cases where there were several possible sources of pain in a large area or more than one quadrant.
The assessors classi®ed the requests as appropriate or inappropriate. These two basic categories were then subdivided subjectively as follows: Appropriate 1: the radiograph provided the information required. Appropriate 2: the request was appropriate but the radiograph did not provide the information required due to technical reasons. Appropriate 3: the request was appropriate but additional views were required. Inappropriate 4: the information required was not available from the radiograph. Inappropriate 5: the information required was available but another technique would have been better (e.g. periapical radiographs). Inappropriate 6: no radiograph was necessary. The category `other' was used for assessments that did not ®t into any of the above list. The radiographs were assessed independently and cases of disagreement resolved jointly. The clinical reasons given for requesting PR were analysed.
The assessors noted whether a student had seen the patient and if the request had been authorised by a junior (house surgeon) or a senior (registrar grade or above) member of sta. Thus there were four dierent sources of requests; student supervised by junior sta, student supervised by senior sta, junior sta and senior sta. The assessors also noted whether there were any incidental ®ndings from the radiographs that were clinically signi®cant, i.e. that might change the management of the patient. In cases where PR was considered inappropriate, the assessors decided what radiographs should have been requested. The dierence in eective dose (E) between the PR and the preferred radiographs was based on the data of White6 who gives a value of of 6.7 mSv for a Pr using rare earth screens and 84 mSv for a full-mouth survey of 20 ®lms with D speed ®lm and round collimation6. We obtained intra-oral radiographs with E speed ®lm and rectangular collimation, each of which reduces the eective dose by half.5,7 Therefore we considered E for one periapical radiograph to be 1.1 mSv. E for an upper standard occlusal radiograph is quoted as between 2 and 10 mSv.4 Since this ®gure is not based on published literature, we chose the higher end of the range for our calculations. The level of agreement between the two assessors was assessed by applying Cohen's k. After 12 months, 30 cases (approximately 10%) were reassessed in order to evaluate the level of intra-observer repeatability.
261
Results The categorisation of requests is illustrated in Table 1 One hundred and ®fty-®ve requests (58%) were considered appropriate (categories 1 ± 3). In 152 of these cases (98%) the radiograph provided the information required. One hundred and fourteen requests (42%) were considered inappropriate. In 95 of these cases (83%) the information was available from the radiograph but another technique would have been better (Inappropriate 5). In 17 cases (15%) no radiograph was indicated (Inappropriate 6), and in the remaining two cases the information required was not available from the radiograph (Inappropriate 4). Table 1 Requests for panoramic radiography categorised after joint review by two dental radiologists Categorya Appropriate 1 Appropriate 2 Appropriate 3 Inappropriate 4 Inappropriate 5 Inappropriate 6 Other Total
Number of requests (%) 152 (56.1) 1 (0.4) 2 (0.7) 2 (0.7) 95 (35.1) 17 (6.3) 2 (0.7) 271
a
For de®nitions, see Methods Dentomaxillofacial Radiology
Panoramic radiography J Sewell et al
262
The clinical details given for the 114 inappropriate requests are summarised in Table 2. In 54 instances (47%) the radiograph was being used to assess one or two teeth. The next most common reason was to assess pain or swelling in one quadrant (n=15, 13%). The distribution of appropriate and inappropriate requests from each group of initiators is shown in Table 3. Dental students were involved in 186 cases and 76 (41%) of their requests were inappropriate. Sixty-one of these inappropriate requests were authorised by senior sta and 15 were authorised by junior sta. In total, ®ve radiographs (2%) had incidental ®ndings of clinical signi®cance, i.e. the ®nding may have altered the treatment for that patient. Three of these incidental ®ndings were in cases where the PR was considered inappropriate. These included: possible solitary bone cyst in the mandible, retained roots that required extraction and multiple carious teeth that required treatment (which could have been detected clinically). There were no incidental ®ndings of benign or malignant neoplasia. One approximate calculation of the total eective dose of the inappropriate requests is shown in Table 4. It can be seen that the 114 radiographs taken gave an estimated dose of 764 mSv, whereas the preferred radiographs would have reduced this by approximately 70% to 233 mSv.
Table 2 Clinical reasons for inappropriate requests for panoramic radiography Number of requests (%)
Clinical reason
Assessment of 1 ± 2 teeth (caries, fracture, abscess etc) 54 Pain/swelling one quadrant 15 Pain/swelling in two or more quadrants 9 Pericoronitis/pain in one third molar tooth 7 Assessment of 3 ± 4 teeth 5 Multiple extractions/multiple carious teeth 5 Isolated trauma to incisors 5 General view/dental assessment 5 Temporomandibular joint dysfunction 3 Pain in two third molar teeth 2 Other 4 Total 114
(47.4) (13.2) (7.9) (6.1) (4.4) (4.4) (4.4) (4.4) (2.6) (1.8) (3.5)
Table 3 Source of inappropriate requests. Values in parentheses are percentages of total number of requests in each category No. of No. of inappropriate requests requests (A) Student request authorised by junior staff (B) Student request authorised by senior staff (C) Junior staff request (D) Senior staff request Total student requests (A+B) Total requests involving junior staff (A+C) Total requests involving senior staff (B+D) Dentomaxillofacial Radiology
74 112 51 34 186 125 146
15 61 21 17 76 36 77
(20) (54) (41) (50) (41) (29) (53)
Table 4 Comparison of calculated effective dose (E) from inappropriately requested panoramic and the preferred radiographs RadioE Total graph No. (mSv) (mSv)
Preferred radiograph
PR
Periapical 157 USO 2 Sectional PR 10 TMJ program 1
114
Total
6.7
763.8
763.8
No.
E Total (mSv) (mSv) 1.1 10 3.35 6.7
172.7 20 33.5 6.7 232.9
Key: USO, upper standard occlusal; PR, panoramic radiograph
In considering whether a request was appropriate or inappropriate, inter-observer agreement was good (k=0.6). It was moderate when the proportion of agreement over all six categories was considered (k=0.4). Intra-observer agreement was also moderate with k=0.52 over all categories and k=0.57 for whether the request was appropriate or inappropriate. Discussion ICRP requires that radiographic examinations are both justi®ed and optimised.6,9 Choosing the most appropriate radiograph to deliver maximum bene®t to the patient for the least radiation exposure is central to this process. The increasing use of PR was one area of concern highlighted by Selection Criteria for Dental Radiography.5 The results of our study show that 42% of the requests for PR from the DA&E were inappropriate. This level in a teaching hospital is a matter for concern, since it is likely that prescribing habits developed as a student would continue after qualifying. Some useful information was available from the radiographs in the majority of inappropriate requests, but the preferred alternative would have given a more detailed image, often with a lower radiation dose. In this study, 6% of the patients underwent an unnecessary radiographic examination. The most common reason for an inappropriate request was in the assessment of one or two teeth for caries, root fracture or possible abscess, the most common reasons why patients attend DA&E. The second most common clinical condition for an inappropriate request was pain or swelling in one quadrant. The radiographs requested were intended to identify apical change, in which case one or two periapical radiographs would have produced better images for less radiation dose.4 Where more teeth or quadrants were involved, periapical radiographs would still have been a better choice, because even though the radiation dose is higher, the better image quality and its higher diagnostic yield justi®es them. PR was particularly inappropriate in cases of trauma to incisor teeth in the absence of any clinical signs of other fractures, since overlying spinal shadow means that this region is the least well shown.10 ± 12 Occlusal or periapical radiographs show much better detail for less or similar dose.
Panoramic radiography J Sewell et al
PR is recommended for the assessment of third molars prior to surgical removal.5 However, for assessment of one or two molars in an emergency clinic, periapical radiographs or a sectional PR, where only the aected quadrant is irradiated, should be considered as a means of dose reduction. In some cases of pericoronitis around a single third molar tooth, the assessors concluded that no radiograph was necessary at all. This was either because the patient already had a recent relevant radiograph or was already under the care of a general dental practitioner. Three patients with TMJ symptoms were considered to have been inappropriately radiographed. These patients presented with symptoms and signs of myofascial pain for which TMJ imaging is not indicated.5,13,14 The ®ve inappropriate cases where the clinical reasons given were general view/dental assessment were considered to require a better clinical evaluation and more targeted radiography. In these cases the PR was being used as a screening technique that has been convincingly refuted in the literature.4 Although agreement between the assessors was not perfect, on joint review it was apparent that the disagreements were largely due to dierences in interpretation of the patients' clinical notes. Once the assessors agreed on the casenotes, they had no diculty in agreeing on the category of the request. It was apparent that about 40% of requests initiated by dental students were inappropriate. The number of errors needs to be reduced and teaching on clinics should reinforce the didactic course to ensure the correct choice of radiographic examination.
Junior and senior sta were inappropriately requesting or authorising up to 29% and 52% respectively of PR. It is interesting that the percentage of inappropriate requests from junior sta supervising students was half that when they were treating patients themselves. Both these groups of sta require continuing education. This could be based on audit of the selection criteria we developed for this study. There were clinically signi®cant incidental ®ndings in three of the inappropriate radiographs. This is a small number and none were serious or potentially lifethreatening. The use of the `screening' DPT to detect occult disease is clearly not supported by this smallscale study. The comparison of the potential saving in dose between the PRs actually taken and the assessors preferred alternatives, was an approximate estimation. There is a wide variation in published doses in dental radiography. With PR it depends on the type of panoramic unit and program used and whether or not the salivary glands are included as radiosensitive organs. We used the lowest available estimate to ensure that the calculated reduction was minimal. The actual dose saving is likely to be greater. In conclusion, the implementation of selection criteria for panoramic radiography would be of bene®t in terms of both diagnostic yield and reduction in radiation dose.
263
Acknowledgements The authors wish to thank Mr D Pinkerton for allowing us to carry out this study within the Dental Accident and Emergency Department.
References 1. Langlais RP, Langland OE, Nortje CJ. Diagnostic Imaging of the Jaws. Philadelphia, Williams and Wilkins, 1995, pp 7 ± 12. 2. Tanner RJ, Wall BF, Shrimpton PC, Hart D, Bungay DR. Frequency of medical and dental examinations in the UK. 1997/ 98 Chilton, NRPB-R320, 2001. 3. Whaites E. Essentials of Dental Radiography and Radiology 2nd edn. Edinburgh: Churchill Livingstone, 1996, p 162. 4. Rushton VE, Horner K. The use of panoramic radiology in dental practice. J Dent 1996; 24: 185 ± 201. 5. Faculty of General Dental Practitioners (UK). Selection criteria for dental radiography. London: Royal College of Surgeons of England, 1998. 6. White SC. Assessment of radiation risk from dental radiography. Dentomaxillofac Radiol 1992; 21: 118 ± 126. 7. Velders XL, van Aken J, van der Stelt PF. Risk assessment from bitewing radiography. Dentomaxillofac Radiol 1991; 20: 209 ± 213. 8. Robson C. Real World Research: A Resource for Social Scientists and Practitioner-Researchers. Oxford: Blackwell, 1993, p 222 ± 223. 9. ICRP 1990 Recommendations of the International Commission on Radiation Protection, ICRP Publication 60. Ann ICRP 1990; 21: Nos 1 ± 3.
10. Ohba T, Katayama H. Comparison of orthopantomography with conventional periapical dental radiography. Oral Surg Oral Med Oral Pathol 1972; 34: 524 ± 530. 11. Douglass CW, Valachovic RW, Wijesinha A, Chauncey HH, Kapur KK, McNeil BJ. Clinical ecacy of dental radiography in the detection of dental caries and periodontal diseases. Oral Surg Oral Med Oral Path 1986; 62: 330 ± 339. 12. Molander B, Ahlqwist M, Grondahl HG, Hollender L. Comparison of panoramic and intraoral radiography for the diagnosis of caries and periapical pathology. Dentomaxillofac Radiol 1993; 22: 28 ± 32. 13. Brooks SB, Brand JW, Gibbs SJ, Hollender L, Lurie AG, Omnell KA et al. Imaging of the temporomandibular joint: a position paper of the American Academy of Oral and Maxillofacial Radiology. Oral Surg Oral Med Oral Pathol Oral Radiol Endodont 1997; 83: 609 ± 18. 14. McNeil C, Mohl ND, Rugh JD, Tanka TT. Temporomandibular disorders: diagnosis, management, education, and research. J Am Dent Assoc 1990; 120: 253 ± 263.
Dentomaxillofacial Radiology
