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A quantitative analysis of dental radiography quality assurance practices among North Carolina dentists
A quantitative analysis of dental radiography quality assurance practices among North Carolina dentists Enrique Platin, RT(RT),(QM), MS, EdD, a Apirum Janhom, DDS, MS, b and Donald Tyndall, DDS, MPH, PhD, c Chapel Hill, N.C., and Amsterdam, The Netherlands UNIVERSITYOF NORTH CAROLINASCHOOL OF DENTISTRYAND LOUWESWEGI AMSTERDAM
Objective. The purpose of this study was to assess the level of compliance with dental radiography quality assurance recommendations on the part of dental practitioners in the state of North Carolina and to determine whether the age of the practice was an influential factor affecting compliance. Study Design. On-site survey inspections by state officials using measurement devices and questionnaires were used to assess x-ray machine parameters and gather information about quality assurance practices in private offices in the state of North Carolina. Results. There were approximately three intraoral units per facility, with an average entrance skin exposure of 267 mR per bitewing radiograph. There were no significant differences associated with the age of the practice in quality assurance practices except with respect to the type of processor used: dentists who had been in practice for more than 20 years used manual processing more frequently than those who had been in practice for less than 20 years (p = 0.001). Conclusions. Most practices showed a high level of compliance with equipment function requirements. North Carolina dentists are making an effort to comply with the American Academy of Oral and Maxillofacial Radiology recommendations. However, the use of faster film and rectangular collimation was much less than expected. Only 9% of the participants reported using E-speed film exclusively, and only 7.33% reported using rectangular collimation. (Oral Surg Oral Med Oral Pathel Oral Radiol Ended 1998;86:115-20)
Dental radiology quality assurance practices have been investigated for quite some time. 1-7 Since 1979 the Food and Drug Administration has strongly advocated the implementation of quality assurance programs in diagnostic radiology facilities, including private dental clinics, s The primary goals of quality assurance have been to decrease unnecessary radiation exposure to patients and to increase the quality of the images produced. However, several studies have indicated that many diagnostic radiology facilities produce images of poor quality, which necessitates retakes and results in unnecessary radiation exposure to patients. 9 -13 Results from a broad range of dental practices have revealed that optimum radiographic quality assurance practices are not being implemented universally in dental clinics. Beideman et al. 14 evaluated preapproved radiographs submitted to a third party and found that more than 50% of the radiographs were substandard in quality; they reported that with respect to density errors more films were found to be dark than light. It has also been suggested that dentists may increase radiation exposure aClinical Assistant Professor, Diagnostic Sciences Department, University of North Carolina School of Dentistry. bGraduate student in Oral and Maxillofacial Radiology, Academic Center for Dentistry Amsterdam, Department of Oral Radiology, Louwesweg I Amsterdam. CAssociateProfessor, Diagnostic Sciences Department, University of North Carolina School of Dentistry. Received for publication July 28, 1997; returned for revision Sept. 22, 1997; accepted for publication Jan. 12, 1998. Copyright © 1998 by Mosby, Inc. 1079-2104/98/$5.00 + 0 7/16/89765
to compensate for improper processing. 15,16 Other data from dental radiology practices in Virginia and Florida have shown that offices that use manual processing tend to underdevelop, underfix, and not change solutions as frequently as required. 17 The same survey also found many film processing facilities to have excessive light and poor light seals between the door and the floor. Kantor et a1.1 reported that many of the radiographs in their study were not of diagnostic quality and that 28% to 55% of all nondiagnostic radiographs resulted from technical errors. These results parallel those of previous studies by Jensen et at.9 and Collett. 1° One of the most efficient ways to increase image quality and reduce unnecessary radiation exposure to patients is to decrease the number of retakes and pitfalls caused by equipment failure. This effort can be easily accomplished through proper maintenance of equipment function, as recommended by the American Dental Association (ADA) and the American Academy of Oral and Maxillofacial Radiology (AAOMR).18 Also recommended is the use of film holders, faster films, intensifying screens with a high x-ray conversion efficiency, and rectangular collimators. The ADA, through the Council on Dental Materials, Instruments, and Equipment, recommends the use of optimal techniques to promote safety and effectiveness in radiographic practices. 19 The recommendations have been periodically updated and the guidelines made available to dental practitioners. In 1983 the A A O M R proposed specific recommendations for quality assurance in dental radiology. 18 These recommendations
115
116 Platin, Janhom, and Tyndall
ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY
July 1998 Table I. Quality assurance recommendations (adapted from the AAOMR Recommendations for Quality Assurance in Dental Radiology 18) Yearly
Semiannually
Monthly Dally
Check reproducibility of x-ray output Check representative entrance skin exposure Check reproducibility and accuracy of kil0voltage Check reproducibility and accuracy of timer stations Check linearity and accuracy of milliamperage Check assessment of half value layer Check stability of tube head Perform determination of beam alignment and beam size diameter Check cassettes Clean intensifying screens Check safe-lighting conditions Check darkroom conditions (light tightness) Check viewing conditions and viewboxes Clean darkroom Perform processor quality control test Use retake logs Use leaded aprons on all patients Use selection criteria Use the fastest image receptor systems
classified dental facilities into three stages according to the level of skill and radiographic procedures performed. The recommendations include a baseline quality assurance program that should be implemented in all dental clinics regardless of the level of radiographic activity (Table I). The basic program consists of reference films, a retake log, a monthly check of viewboxes, a yearly test of x-ray generators, a monthly assessment of darkroom conditions, and daily monitoring of processing. The role of quality assurance has been well established in medical radiology for quite some time. Quality assurance has been proved to be an effective means of monitoring and improving image quality. As mentioned earlier, however, studies in dentistry consistently suggest that the use of quality assurance and dose-reducing techniques and the incorporation of the AAOMR and ADA recommendations for quality assurance practices have not been fully implemented by dental professionals. In view of these findings, this study set out to assess the degree of compliance with the AAOMR dental radiography quality assurance recommendations by dentists in the state of North Carolina. The authors also investigated whether the age of the practice was a significant variable influencing adoption of the recommendations; a previous study had found the age of the practice to be a predictive variable in the adoption of quality assurance practices. 7 The null hypothesis for this study was that there was no significant difference in quality assurance practices among dental practitioners associated with the age of the practice.
Table II. Percentage of practitioners by age of practice Age of practice (yr) Practitioners (%)
1-5 13.63
5-10 16.32
10-15 18.92
15-20 15.93
20+ 35.20
MATERIAL A N D METHODS There were 355 private dental offices surveyed in this study. The sample was randomly selected from a list of dental offices that were scheduled to be inspected by the North Carolina Department of Environment, Health, and Natural Resources, Division of Radiation Protection, during calendar years 1994 and 1995. The data collection instrument consisted of two parts: an official survey form developed and used by the North Carolina Division of Radiation Protection to collect data on radiation safety compliance, and a questionnaire developed by the investigators. The first part of the survey collected information regarding the overall conditions of x-ray machines, safety procedures used, and the conditions of darkroom facilities. In addition, actual measurements of x-ray machine parameters in each facility were recorded. The parameters evaluated were exposure linearity, accuracy of exposure timer, kilovoltage, halfvalue layer measurement (HVL), entrance skin exposure (ESE), beam size, and source-to-image distance measurements. The second part of the instrument was developed by a panel of experts consisting of two oral and maxillofacial radiologists, a radiologic science educator, and three radiation safety inspectors. It collected information on demographic characteristics, such as age and type of practice, and information on general quality assurance methods used, including frequency of machine inspections, frequency of processing-solution changes, replenishment procedures, and types of processors, film, and film holders used. The data were collected by seven radiation safety inspectors who were calibrated on the use of the survey instruments. The data were entered and analyzed by means of SYSTAT (version 5.2) software for Macintosh (SYSTAT, Inc., Evanston, Ill.). Chi-square tests were used to evaluate the significance of age of practice, and descriptive statistics were used to depict patterns and describe the common radiographic practices of those surveyed. RESULTS Of the 355 dental practices included in this survey, 86% were general practices and 14% were specialty practices representing different disciplines. In total, 937 intraoral x-ray machines were inspected, for an average of nearly 3 machines per office. Sixty-seven percent of the respondents owned panoramic machines. Approximately one third had been in practice for 20 years or more, another one third from
ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY
Platin, Janhom, and Tyndall 117
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Film speed and film holders As depicted in Fig. 1, most practices (89.92%) reported using D-speed film, with 9.06% using Espeed film and 1.02% using both. Ninety-three percent used film holders; two practices reported using the patient's fingers to hold the films, and less than 7% did not answer the question about film holding. The Stabe disposable bite block (Rinn Corporation, Elgin, Ill.) was the most commonly used film holder, accounting for 51% of the total; this was followed by the XCP (Rinn Corporation), which accounted for 21.28%. The Precision Instrument (Masel Orthodontics, Bristol, Pa.) was used by 5.53% of the respondents and. the Snap-A-Ray (Rinn Corporation) by 11.28%; other holders were used by 10.91%. Chi-square tests demonstrated no significant difference in the use of E-speed film or film holders associated with the age of the practice (p > 0.5).
Intensifying screens Eighty-four percent of the respondents indicated using rare-earth intensifying screens for extraoral techniques; 16% reported using calcium tungstate intensifying screens (Fig. 1). Twenty-two percent reported cleaning intensifying screens monthly, 22% every 6 months, and 12.38% once per year; the remainder of the respondents cleaned their screens at other intervals. A
chi-square test demonstrated no significant difference associated with the age of the practice with respect to either the use of rare-earth intensifying screens or their maintenance (p > 0.5).
Processing Seventy-nine percent of the respondents used automatic processors, 19.00% manual proceSsors, and 2% both (Fig. 2). Darkroom conditions were reported as light-tight in 79% of the practices; 21% of darkrooms had light leaks around the door flames. Seventy-one percent of practices reported using visual inspections to assess processing conditions, 1.32% reported using sensitometry, 2.64% reported using film strips, and 25.04% reported using no assessment method. With regard to the replenishment of chemical solutions, 63.24% of practices used manual techniques, 23.93% automatic techniques, and 1.7% no techniques; 11.13% did not respond. The largest proportion of the respondents (30.57%) changed their processing solutions monthly, 28.85% biweekly, 27.14% weekly, and 13.44% only "when needed" There were no significant differences in the processing quality assurance practices among the age-of-practice groups except with respect to the use of manual processing by dentists who reported having been in practice for more than 20 years (p = 0.001).
Intraoral equipment X-ray equipment was checked annually by 40.15% of respondents (Fig. 3) and every 3 years by 37.42%; the remaining 22.43% reported using other time intervals.
118 Platin,Janhom, and Tyndall
ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY
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The tube potentials used by the respondents in this study ranged from 45 to 100 kVp; only 6.8% of the machines were operated below 60 kVp. The most common operating potential was 70 kVp (57.8%), followed by 65 kVp (14.10%), and 90 kVp (7.4%). The operating tube currents ranged from 5 to 20 mA, with the most common current being 10 mA (29.71%), followed by 7 mA (26.85%) and 15 mA (21.72%). Exposure timer precision was reported to be within the limits of 15% accuracy in 88% of the machines tested. The most common (95.54%) position-indicatingdevice (PID) used in this survey was the round, open-ended variety (>8 inches). Only 4.46% of the respondents used PIDs less than 8 inches long, and only a few (1.8%) reported using rectangular PIDs. Most (97.04%) of the machines had beam diameters no greater than 2.75 inches, with a small percentage falling outside of the allowablelimit. Ninety-fivepercent of the machines were found to have acceptable HVL measurements. The average ESE for bitewing radiographs was calculated to be 267 mR, and most (80%) of the machines tested produced acceptable ESE values. No significant differences associated with the age of the practice were found in quality assurance practices for intraoral equipment (p > 0.05).
DISCUSSION
The number of practices using E-speed film exclusively was only 9%; this compared with 11% to 25% reported in previous surveys. This suggests that E-speed film continues to be unpopular among practicing dentists. 3,4,6,7 The introduction of the more advanced formula found in Ektaspeed Plus film (Eastman Kodak Co., Rochester, N.Y.) should increase the acceptance of E-speed film, because research has shown this film to be not only equivalent to D-speed film in diagnostic quality but also in some cases more tolerant to lessthan-ideal processing conditions.2°-24 Although most participants reported using film holders, only 7.33% used rectangular collimation; 5.53% used Precision Instruments and 1.8% rectangular P1Ds. This finding indicates that practitioners are not taking advantage of the rectangular collimation method to improve image contrast and minimize patient dose. The use of rectangular collimators has been recommended since 1972 by the ADA Council on Dental Materials. The intervals used for cleaning intensifying screens varied. Only 22% of the respondents cleaned intensifying screens according to the recommendations,When these results were compared with those of a previous study, the percentage of respondents who cleaned intensifying screens according to the recommendations was seen to have apparently increased from 10% to 22%.7
ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY Volume 86, Number 1
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Platin, Janhom, and Tyndall 119
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Fig. 3. Percentage of compliance with AAOMR recommendations. The A A O M R recommends the use of kilovoltages between 60 and 100. Our study found a high percentage (93.2%) of compliance with this recommendation, as well as a high degree of exposure timer accuracy. HVL measurements coincided with the recommended values. Overall, the average mean ESE from dental bitewing films was relatively low (267 mR) in comparison with that reported in the Nationwide Evaluation of X-ray Trends (334 mR).25 This figure could be reduced further with the universal use of E-speed film. The results of our study showed that dentists in the state of North Carolina perform some level of quality assurance in their radiographic practices, although not always in agreement with the A A O M R recommendations (Fig. 3). These results, when compared with other findings, are encouraging; however, promotion of the use of E-speed film will result in a reduction of radiation exposure to patients, and promotion of the use of rectangular collimation will result in both an overall reduction of patient dose and an increase in the quality of the images produced. CONCLUSIONS From the results of the study we drew the following conclusions: 1. Inasmuch as only a small percentage of practitioners reported using E-speed film, the benefits of using faster film that provides the same diagnostic information needs to be reemphasized. 2. Only a small number of practitioners used rectangular collimation. The use of rectangular collimators should be recommended; emphasis needs to be
placed on overall improvement in image quality and reduction in patient dose. 3. There were no significant differences in quality assurance practices associated with the age of the practice except with respect to the type of processing used; the use of manual processing was reported to be more common in the group of dentists who had been in practice for more than 20 years. 4. Respondents demonstrated an effort to maintain some level of quality assurance, especially in areas dealing with kilovoltage, milliamperage, timer accuracy, HVL, use of some type of quality control for processing assessment, use of rare-earth intensifying screens for extraoral techniques, and use of a beam of the recommended diameter. 5. There were approximately three intraoral units per facility, and the ESE averaged 267 mR per bitewing radiograph. This figure could be decreased with the universal use of faster film. REFERENCES 1. Kantor ML, Hunt RJ, Morris AL. An evaluation of radiographic equipment and procedures in 300 dental offices in the United States. J Am Dent Assoc 1990;120:547-50. 2. Farman AG, Hines VG. Radiation safety and quality assurance in North American dental schools. J Dent Educ 1986;50:304-8. 3. Bohay RN, Kogon SL, Stephen RG. A survey of radiographic techniques and equipment used by a sample of general dental practitioners. Oral Surg Oral Med Oral Pathol 1994;78:806-10. 4. Nakfoor CA, Brooks SL. Complianceof Michigan dentists with radiographic safety recommendations. Oral Surg Oral Med Oral Pathol 1992;73:510-3. 5. Brezden NA, Brooks SL. Evaluation of panoramic dental radiographs taken in private practice. Oral Surg Oral Med Oral Pathol 1987;63:617-21.
120 Platin, Janhom, and Tyndall
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July 1998 6. Ooren AD, Sciubba JJ, Friedman R, Malamud H. Survey of radiologic practices among dental practitioners. Oral Surg Oral Med Oral Pathol 1989;67:464-8. 7. Platin E, Ludlow JB. Knowledge and adoption of radiographic quality assurance guidelines by general dentists in North Carolina. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1995;79:122-6. 8. US Food and Drug Administration. Quality assurance programs for diagnostic radiology facilities. Final recommendation (FDA 80-8110). Federal Register 1979;44:71728-40. 9. Jensen OE, Handelman SL, Iker HE Use and quality of bitewing films in private dental offices. Oral Surg Oral Med Oral Pathol 1987;63:249-53. 10. Collett WK. Intraoral radiographic errors in films submitted for orthodontic consultation. Oral Surg Oral Med Oral Pathol 1980; 49:370-2. 11. Svenson B, Eriksson T, Kronstrrm M, Palmqvist A. Image quality of intraoral radiograptas used by general practitioners in prosthodontic treatment planning. Dentomaxillofacial Radiology 1994;23:46-8. 12. Horner K. Review article: radiation protection in dental radiology. Br J Radinl 1994;67:1041-9. 13. Gibbs SJ, Pujol A, Chen T-S, Malcom AW, James AE. Patient risk from interproximal radiography. Oral Surg Oral Med Oral Pathol 1984;58:347-54. 14. Beideman RW, Johnson ON, Alcox RW. A study to develop a rating system and evaluate dental radiographs submitted to a third party carrier. J Am Dent Assoc 1976;93:1010-13. 15. US Department of Health, Education, and Welfare, Bureau of Radiologicai Health. Nationwide evaluation of x-ray trends (publication no. FDA 76-8003). Rockville, Md.: HEW; June 1975. 16. Crabtree CL. DENT program (dental exposure normalization technique). Medicine Hygiene. No. 1440. October 1981. 17. Kaugers GE, Broga DW, Collett WK. Dental radiologic survey of Virginia and Florida. Oral Surg Oral Med Oral Pathol 1985;60: 225-9.
18. American Academy of Dental Radiology. Recommendations for quality assurance in dental radiography. Oral Surg Oral Med Oral Pathol 1983;55:421-6. 19. Council on Dental Materials, Instruments and Equipment. Recommendations in radiographic practices. J Am Dent Assoc 1981;103:103-4. 20. Grondahl K, Grondahl H-G, Olving A. A comparison of Kodak Ektaspeed and Ultraspeed films for the detection of periodontal bone lesions. Dentomaxillofac Radiol 1983;12:43-6. 21. Thunthy KH, Weinberg R. Sensitometric comparison of dental films of group D and E. Oral Surg Oral Med Oral Pathol 1982;54:250-2. 22. Ludlow JB, Platin E. Densitometric comparison of Ultra-speed, Ektaspeed, and Ektaspeed Plus intraoral films for two processing conditions. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1995;79:105-13. 23. Ludlow JB, Platin E. Delano EO, Clifton L. The efficacy of caries detection using three intraoral films under different processing conditions. J Am Dent Assoc 1997;128:1401-8. 24. Frommer HH, Jaln RK. A comparative clinical study of group D & E dental film. Oral Surg Oral Med Oral Pathol 1987;63:73842. 25. National Council on Radiation Protection and Measurements. Exposure of the US population from diagnostic medical radiation: report no. 100. Bethesda, Md.: National Council on Radiation Protection and Measurements; 1989. p. 34.
Reprint requests: Enrique Platin, RT(RT),(QM), MS, EdD Clinical Assistant Professor Diagnostic Sciences Department University of North Carolina School of Dentistry Chapel Hill, NC 27599-7450
Objective. The purpose of this study was to assess the level of compliance with dental radiography quality assurance recommendations on the part of dental practitioners in the state of North Carolina and to determine whether the age of the practice was an influential factor affecting compliance. Study Design. On-site survey inspections by state officials using measurement devices and questionnaires were used to assess x-ray machine parameters and gather information about quality assurance practices in private offices in the state of North Carolina. Results. There were approximately three intraoral units per facility, with an average entrance skin exposure of 267 mR per bitewing radiograph. There were no significant differences associated with the age of the practice in quality assurance practices except with respect to the type of processor used: dentists who had been in practice for more than 20 years used manual processing more frequently than those who had been in practice for less than 20 years (p = 0.001). Conclusions. Most practices showed a high level of compliance with equipment function requirements. North Carolina dentists are making an effort to comply with the American Academy of Oral and Maxillofacial Radiology recommendations. However, the use of faster film and rectangular collimation was much less than expected. Only 9% of the participants reported using E-speed film exclusively, and only 7.33% reported using rectangular collimation. (Oral Surg Oral Med Oral Pathel Oral Radiol Ended 1998;86:115-20)
Dental radiology quality assurance practices have been investigated for quite some time. 1-7 Since 1979 the Food and Drug Administration has strongly advocated the implementation of quality assurance programs in diagnostic radiology facilities, including private dental clinics, s The primary goals of quality assurance have been to decrease unnecessary radiation exposure to patients and to increase the quality of the images produced. However, several studies have indicated that many diagnostic radiology facilities produce images of poor quality, which necessitates retakes and results in unnecessary radiation exposure to patients. 9 -13 Results from a broad range of dental practices have revealed that optimum radiographic quality assurance practices are not being implemented universally in dental clinics. Beideman et al. 14 evaluated preapproved radiographs submitted to a third party and found that more than 50% of the radiographs were substandard in quality; they reported that with respect to density errors more films were found to be dark than light. It has also been suggested that dentists may increase radiation exposure aClinical Assistant Professor, Diagnostic Sciences Department, University of North Carolina School of Dentistry. bGraduate student in Oral and Maxillofacial Radiology, Academic Center for Dentistry Amsterdam, Department of Oral Radiology, Louwesweg I Amsterdam. CAssociateProfessor, Diagnostic Sciences Department, University of North Carolina School of Dentistry. Received for publication July 28, 1997; returned for revision Sept. 22, 1997; accepted for publication Jan. 12, 1998. Copyright © 1998 by Mosby, Inc. 1079-2104/98/$5.00 + 0 7/16/89765
to compensate for improper processing. 15,16 Other data from dental radiology practices in Virginia and Florida have shown that offices that use manual processing tend to underdevelop, underfix, and not change solutions as frequently as required. 17 The same survey also found many film processing facilities to have excessive light and poor light seals between the door and the floor. Kantor et a1.1 reported that many of the radiographs in their study were not of diagnostic quality and that 28% to 55% of all nondiagnostic radiographs resulted from technical errors. These results parallel those of previous studies by Jensen et at.9 and Collett. 1° One of the most efficient ways to increase image quality and reduce unnecessary radiation exposure to patients is to decrease the number of retakes and pitfalls caused by equipment failure. This effort can be easily accomplished through proper maintenance of equipment function, as recommended by the American Dental Association (ADA) and the American Academy of Oral and Maxillofacial Radiology (AAOMR).18 Also recommended is the use of film holders, faster films, intensifying screens with a high x-ray conversion efficiency, and rectangular collimators. The ADA, through the Council on Dental Materials, Instruments, and Equipment, recommends the use of optimal techniques to promote safety and effectiveness in radiographic practices. 19 The recommendations have been periodically updated and the guidelines made available to dental practitioners. In 1983 the A A O M R proposed specific recommendations for quality assurance in dental radiology. 18 These recommendations
115
116 Platin, Janhom, and Tyndall
ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY
July 1998 Table I. Quality assurance recommendations (adapted from the AAOMR Recommendations for Quality Assurance in Dental Radiology 18) Yearly
Semiannually
Monthly Dally
Check reproducibility of x-ray output Check representative entrance skin exposure Check reproducibility and accuracy of kil0voltage Check reproducibility and accuracy of timer stations Check linearity and accuracy of milliamperage Check assessment of half value layer Check stability of tube head Perform determination of beam alignment and beam size diameter Check cassettes Clean intensifying screens Check safe-lighting conditions Check darkroom conditions (light tightness) Check viewing conditions and viewboxes Clean darkroom Perform processor quality control test Use retake logs Use leaded aprons on all patients Use selection criteria Use the fastest image receptor systems
classified dental facilities into three stages according to the level of skill and radiographic procedures performed. The recommendations include a baseline quality assurance program that should be implemented in all dental clinics regardless of the level of radiographic activity (Table I). The basic program consists of reference films, a retake log, a monthly check of viewboxes, a yearly test of x-ray generators, a monthly assessment of darkroom conditions, and daily monitoring of processing. The role of quality assurance has been well established in medical radiology for quite some time. Quality assurance has been proved to be an effective means of monitoring and improving image quality. As mentioned earlier, however, studies in dentistry consistently suggest that the use of quality assurance and dose-reducing techniques and the incorporation of the AAOMR and ADA recommendations for quality assurance practices have not been fully implemented by dental professionals. In view of these findings, this study set out to assess the degree of compliance with the AAOMR dental radiography quality assurance recommendations by dentists in the state of North Carolina. The authors also investigated whether the age of the practice was a significant variable influencing adoption of the recommendations; a previous study had found the age of the practice to be a predictive variable in the adoption of quality assurance practices. 7 The null hypothesis for this study was that there was no significant difference in quality assurance practices among dental practitioners associated with the age of the practice.
Table II. Percentage of practitioners by age of practice Age of practice (yr) Practitioners (%)
1-5 13.63
5-10 16.32
10-15 18.92
15-20 15.93
20+ 35.20
MATERIAL A N D METHODS There were 355 private dental offices surveyed in this study. The sample was randomly selected from a list of dental offices that were scheduled to be inspected by the North Carolina Department of Environment, Health, and Natural Resources, Division of Radiation Protection, during calendar years 1994 and 1995. The data collection instrument consisted of two parts: an official survey form developed and used by the North Carolina Division of Radiation Protection to collect data on radiation safety compliance, and a questionnaire developed by the investigators. The first part of the survey collected information regarding the overall conditions of x-ray machines, safety procedures used, and the conditions of darkroom facilities. In addition, actual measurements of x-ray machine parameters in each facility were recorded. The parameters evaluated were exposure linearity, accuracy of exposure timer, kilovoltage, halfvalue layer measurement (HVL), entrance skin exposure (ESE), beam size, and source-to-image distance measurements. The second part of the instrument was developed by a panel of experts consisting of two oral and maxillofacial radiologists, a radiologic science educator, and three radiation safety inspectors. It collected information on demographic characteristics, such as age and type of practice, and information on general quality assurance methods used, including frequency of machine inspections, frequency of processing-solution changes, replenishment procedures, and types of processors, film, and film holders used. The data were collected by seven radiation safety inspectors who were calibrated on the use of the survey instruments. The data were entered and analyzed by means of SYSTAT (version 5.2) software for Macintosh (SYSTAT, Inc., Evanston, Ill.). Chi-square tests were used to evaluate the significance of age of practice, and descriptive statistics were used to depict patterns and describe the common radiographic practices of those surveyed. RESULTS Of the 355 dental practices included in this survey, 86% were general practices and 14% were specialty practices representing different disciplines. In total, 937 intraoral x-ray machines were inspected, for an average of nearly 3 machines per office. Sixty-seven percent of the respondents owned panoramic machines. Approximately one third had been in practice for 20 years or more, another one third from
ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY
Platin, Janhom, and Tyndall 117
Volume 86, Number 1
90-
D Speed
are Earth 807060"
~
50"
Stabe
40" 30-
iiXCP
Once Pe
Month
20100
La~m,ed..~ !ii!i
a-/~ i
iliiL
Film Type
Image Holders
i
i ''
iii!li!~"0nce Per Year
~
Intensifying Screens
!!iii,,liiii Screen Cleaning
Fig. 1. Image holders and receptors. 11 to 20 years, and the remainder for 10 years or less (Table II).
Film speed and film holders As depicted in Fig. 1, most practices (89.92%) reported using D-speed film, with 9.06% using Espeed film and 1.02% using both. Ninety-three percent used film holders; two practices reported using the patient's fingers to hold the films, and less than 7% did not answer the question about film holding. The Stabe disposable bite block (Rinn Corporation, Elgin, Ill.) was the most commonly used film holder, accounting for 51% of the total; this was followed by the XCP (Rinn Corporation), which accounted for 21.28%. The Precision Instrument (Masel Orthodontics, Bristol, Pa.) was used by 5.53% of the respondents and. the Snap-A-Ray (Rinn Corporation) by 11.28%; other holders were used by 10.91%. Chi-square tests demonstrated no significant difference in the use of E-speed film or film holders associated with the age of the practice (p > 0.5).
Intensifying screens Eighty-four percent of the respondents indicated using rare-earth intensifying screens for extraoral techniques; 16% reported using calcium tungstate intensifying screens (Fig. 1). Twenty-two percent reported cleaning intensifying screens monthly, 22% every 6 months, and 12.38% once per year; the remainder of the respondents cleaned their screens at other intervals. A
chi-square test demonstrated no significant difference associated with the age of the practice with respect to either the use of rare-earth intensifying screens or their maintenance (p > 0.5).
Processing Seventy-nine percent of the respondents used automatic processors, 19.00% manual proceSsors, and 2% both (Fig. 2). Darkroom conditions were reported as light-tight in 79% of the practices; 21% of darkrooms had light leaks around the door flames. Seventy-one percent of practices reported using visual inspections to assess processing conditions, 1.32% reported using sensitometry, 2.64% reported using film strips, and 25.04% reported using no assessment method. With regard to the replenishment of chemical solutions, 63.24% of practices used manual techniques, 23.93% automatic techniques, and 1.7% no techniques; 11.13% did not respond. The largest proportion of the respondents (30.57%) changed their processing solutions monthly, 28.85% biweekly, 27.14% weekly, and 13.44% only "when needed" There were no significant differences in the processing quality assurance practices among the age-of-practice groups except with respect to the use of manual processing by dentists who reported having been in practice for more than 20 years (p = 0.001).
Intraoral equipment X-ray equipment was checked annually by 40.15% of respondents (Fig. 3) and every 3 years by 37.42%; the remaining 22.43% reported using other time intervals.
118 Platin,Janhom, and Tyndall
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The tube potentials used by the respondents in this study ranged from 45 to 100 kVp; only 6.8% of the machines were operated below 60 kVp. The most common operating potential was 70 kVp (57.8%), followed by 65 kVp (14.10%), and 90 kVp (7.4%). The operating tube currents ranged from 5 to 20 mA, with the most common current being 10 mA (29.71%), followed by 7 mA (26.85%) and 15 mA (21.72%). Exposure timer precision was reported to be within the limits of 15% accuracy in 88% of the machines tested. The most common (95.54%) position-indicatingdevice (PID) used in this survey was the round, open-ended variety (>8 inches). Only 4.46% of the respondents used PIDs less than 8 inches long, and only a few (1.8%) reported using rectangular PIDs. Most (97.04%) of the machines had beam diameters no greater than 2.75 inches, with a small percentage falling outside of the allowablelimit. Ninety-fivepercent of the machines were found to have acceptable HVL measurements. The average ESE for bitewing radiographs was calculated to be 267 mR, and most (80%) of the machines tested produced acceptable ESE values. No significant differences associated with the age of the practice were found in quality assurance practices for intraoral equipment (p > 0.05).
DISCUSSION
The number of practices using E-speed film exclusively was only 9%; this compared with 11% to 25% reported in previous surveys. This suggests that E-speed film continues to be unpopular among practicing dentists. 3,4,6,7 The introduction of the more advanced formula found in Ektaspeed Plus film (Eastman Kodak Co., Rochester, N.Y.) should increase the acceptance of E-speed film, because research has shown this film to be not only equivalent to D-speed film in diagnostic quality but also in some cases more tolerant to lessthan-ideal processing conditions.2°-24 Although most participants reported using film holders, only 7.33% used rectangular collimation; 5.53% used Precision Instruments and 1.8% rectangular P1Ds. This finding indicates that practitioners are not taking advantage of the rectangular collimation method to improve image contrast and minimize patient dose. The use of rectangular collimators has been recommended since 1972 by the ADA Council on Dental Materials. The intervals used for cleaning intensifying screens varied. Only 22% of the respondents cleaned intensifying screens according to the recommendations,When these results were compared with those of a previous study, the percentage of respondents who cleaned intensifying screens according to the recommendations was seen to have apparently increased from 10% to 22%.7
ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY Volume 86, Number 1
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Fig. 3. Percentage of compliance with AAOMR recommendations. The A A O M R recommends the use of kilovoltages between 60 and 100. Our study found a high percentage (93.2%) of compliance with this recommendation, as well as a high degree of exposure timer accuracy. HVL measurements coincided with the recommended values. Overall, the average mean ESE from dental bitewing films was relatively low (267 mR) in comparison with that reported in the Nationwide Evaluation of X-ray Trends (334 mR).25 This figure could be reduced further with the universal use of E-speed film. The results of our study showed that dentists in the state of North Carolina perform some level of quality assurance in their radiographic practices, although not always in agreement with the A A O M R recommendations (Fig. 3). These results, when compared with other findings, are encouraging; however, promotion of the use of E-speed film will result in a reduction of radiation exposure to patients, and promotion of the use of rectangular collimation will result in both an overall reduction of patient dose and an increase in the quality of the images produced. CONCLUSIONS From the results of the study we drew the following conclusions: 1. Inasmuch as only a small percentage of practitioners reported using E-speed film, the benefits of using faster film that provides the same diagnostic information needs to be reemphasized. 2. Only a small number of practitioners used rectangular collimation. The use of rectangular collimators should be recommended; emphasis needs to be
placed on overall improvement in image quality and reduction in patient dose. 3. There were no significant differences in quality assurance practices associated with the age of the practice except with respect to the type of processing used; the use of manual processing was reported to be more common in the group of dentists who had been in practice for more than 20 years. 4. Respondents demonstrated an effort to maintain some level of quality assurance, especially in areas dealing with kilovoltage, milliamperage, timer accuracy, HVL, use of some type of quality control for processing assessment, use of rare-earth intensifying screens for extraoral techniques, and use of a beam of the recommended diameter. 5. There were approximately three intraoral units per facility, and the ESE averaged 267 mR per bitewing radiograph. This figure could be decreased with the universal use of faster film. REFERENCES 1. Kantor ML, Hunt RJ, Morris AL. An evaluation of radiographic equipment and procedures in 300 dental offices in the United States. J Am Dent Assoc 1990;120:547-50. 2. Farman AG, Hines VG. Radiation safety and quality assurance in North American dental schools. J Dent Educ 1986;50:304-8. 3. Bohay RN, Kogon SL, Stephen RG. A survey of radiographic techniques and equipment used by a sample of general dental practitioners. Oral Surg Oral Med Oral Pathol 1994;78:806-10. 4. Nakfoor CA, Brooks SL. Complianceof Michigan dentists with radiographic safety recommendations. Oral Surg Oral Med Oral Pathol 1992;73:510-3. 5. Brezden NA, Brooks SL. Evaluation of panoramic dental radiographs taken in private practice. Oral Surg Oral Med Oral Pathol 1987;63:617-21.
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July 1998 6. Ooren AD, Sciubba JJ, Friedman R, Malamud H. Survey of radiologic practices among dental practitioners. Oral Surg Oral Med Oral Pathol 1989;67:464-8. 7. Platin E, Ludlow JB. Knowledge and adoption of radiographic quality assurance guidelines by general dentists in North Carolina. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1995;79:122-6. 8. US Food and Drug Administration. Quality assurance programs for diagnostic radiology facilities. Final recommendation (FDA 80-8110). Federal Register 1979;44:71728-40. 9. Jensen OE, Handelman SL, Iker HE Use and quality of bitewing films in private dental offices. Oral Surg Oral Med Oral Pathol 1987;63:249-53. 10. Collett WK. Intraoral radiographic errors in films submitted for orthodontic consultation. Oral Surg Oral Med Oral Pathol 1980; 49:370-2. 11. Svenson B, Eriksson T, Kronstrrm M, Palmqvist A. Image quality of intraoral radiograptas used by general practitioners in prosthodontic treatment planning. Dentomaxillofacial Radiology 1994;23:46-8. 12. Horner K. Review article: radiation protection in dental radiology. Br J Radinl 1994;67:1041-9. 13. Gibbs SJ, Pujol A, Chen T-S, Malcom AW, James AE. Patient risk from interproximal radiography. Oral Surg Oral Med Oral Pathol 1984;58:347-54. 14. Beideman RW, Johnson ON, Alcox RW. A study to develop a rating system and evaluate dental radiographs submitted to a third party carrier. J Am Dent Assoc 1976;93:1010-13. 15. US Department of Health, Education, and Welfare, Bureau of Radiologicai Health. Nationwide evaluation of x-ray trends (publication no. FDA 76-8003). Rockville, Md.: HEW; June 1975. 16. Crabtree CL. DENT program (dental exposure normalization technique). Medicine Hygiene. No. 1440. October 1981. 17. Kaugers GE, Broga DW, Collett WK. Dental radiologic survey of Virginia and Florida. Oral Surg Oral Med Oral Pathol 1985;60: 225-9.
18. American Academy of Dental Radiology. Recommendations for quality assurance in dental radiography. Oral Surg Oral Med Oral Pathol 1983;55:421-6. 19. Council on Dental Materials, Instruments and Equipment. Recommendations in radiographic practices. J Am Dent Assoc 1981;103:103-4. 20. Grondahl K, Grondahl H-G, Olving A. A comparison of Kodak Ektaspeed and Ultraspeed films for the detection of periodontal bone lesions. Dentomaxillofac Radiol 1983;12:43-6. 21. Thunthy KH, Weinberg R. Sensitometric comparison of dental films of group D and E. Oral Surg Oral Med Oral Pathol 1982;54:250-2. 22. Ludlow JB, Platin E. Densitometric comparison of Ultra-speed, Ektaspeed, and Ektaspeed Plus intraoral films for two processing conditions. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1995;79:105-13. 23. Ludlow JB, Platin E. Delano EO, Clifton L. The efficacy of caries detection using three intraoral films under different processing conditions. J Am Dent Assoc 1997;128:1401-8. 24. Frommer HH, Jaln RK. A comparative clinical study of group D & E dental film. Oral Surg Oral Med Oral Pathol 1987;63:73842. 25. National Council on Radiation Protection and Measurements. Exposure of the US population from diagnostic medical radiation: report no. 100. Bethesda, Md.: National Council on Radiation Protection and Measurements; 1989. p. 34.
Reprint requests: Enrique Platin, RT(RT),(QM), MS, EdD Clinical Assistant Professor Diagnostic Sciences Department University of North Carolina School of Dentistry Chapel Hill, NC 27599-7450