Sarah Gray DDS, MS
When using digital radiography, dentists may notice improvements over film-based radiography in working time, radiation dose, dynamic range, storage and image viewing.
This review of mostly observational studies provides extremely limited evidence for some advantages of digital radiography over film-based radiography.
How does film-based radiography compare with digital radiography?
The authors searched the PubMed database with no limits to August 2009. A hand search of task-specific journals supplemented the search. The authors included original research studies, review articles and user surveys comparing film-based radiography to digital radiography. They assessed the following outcomes in separate searches: working time, radiation dose, retakes and errors, dynamic range, access to patient information, image storage, patient comfort, potential for damage, cross-contamination and image viewing.
For working time, the initial search yielded 39 studies and three surveys, few of which compared film with digital receptors. One survey reported a half-hour/day time savings with digital radiography. No studies evaluated the effect of time spent on post-processing and image enhancing. Twenty-seven studies and three surveys reviewed radiographic dose. At least two studies for digital radiography noted dose reduction for "acceptable" single exposures, however smaller sensors may require more images. Fifteen studies found frequent retakes and positioning errors with digital radiography; but no comparisons to film were reported. Similarly, studies comparing dynamic range cited no direct comparison with conventional films, although some digital radiographs may display a "blooming" phenomenon with overexposure. The authors were not able to find any evidence in 27 studies that patient satisfaction is improved with digital radiographs. Thirty-two studies commented on image storage, yet no direct comparison with film was made.
The authors found that working time, radiation dose, dynamic range, storage and image viewing may be enhanced with digital radiography.
Source of Funding:
Importance and Context:
As a part of converting to electronic patient records, practices will have to adopt digital radiography necessitating changes in working routines such image capture, viewing, and archiving. Quality assessment may include audit programs registering accurate numbers of exposures, and programs may be redefined by health authorities. As the use of film-based radiography is phased out, it is important for practitioners to be aware of the risks and benefits of this replacement technology.
Strengths and Weaknesses of the Systematic Review:
The authors used only one database to search for, select and analyze evidence with no identifiable inclusion or exclusion criteria. Incomplete searches, some using a single criterion, resulted in an indiscriminate acceptance of all reports. The absence of a focused clinical question made it difficult to evaluate the evidence. The authors did not evaluate studies for bias or heterogeneity, nor did they report assessments of the validity of the findings. Evidence was not presented in a tabular format, and consisted largely of non-comparative studies and opinion. Although the authors observed some consistent outcomes, the strength of the evidence was poor. This review could have been strengthened by limiting the number of variables and focusing on articles that included a direct comparison between analog and digital radiography.
Strengths and Weaknesses of the Evidence:
The authors evaluated studies that were largely observational, with few experimental studies that permitted unbiased direct comparisons of outcomes for film and digital technologies. The quantity and quality of evidence were not adequate to form any definitive conclusions.
Implications for Dental Practice:
The authors cited several challenges with digital radiography including JPEG rate, image compression, and potential for fraud. Additional challenges reported include patient discomfort, image degradation and cross-contamination among patients when reusing sensors. Regardless, it is likely that digital radiography will ultimately replace film-based radiography and dental practitioners must be knowledgeable and prepared to cope with the advantages and disadvantages of digital radiography.