Measurement accuracy and perceived quality of imaging systems for the evaluation of periodontal structures

Optimizing the reconstruction filter in cone-beam CT to improve periodontal ligament space visualization: An in vitro study

Purpose

Evaluation of alveolar bone is important in the diagnosis of dental diseases. The periodontal ligament space is difficult to clearly depict in cone-beam computed tomography images because the reconstruction filter conditions during image processing cause image blurring, resulting in decreased spatial resolution. We examined different reconstruction filters to assess their ability to improve spatial resolution and allow for a clearer visualization of the periodontal ligament space.

Materials and Methods

Cone-beam computed tomography projections of 2 skull phantoms were reconstructed using 6 reconstruction conditions and then compared using the Thurstone paired comparison method. Physical evaluations, including the modulation transfer function and the Wiener spectrum, as well as an assessment of space visibility, were undertaken using experimental phantoms.

Results

Image reconstruction using a modified Shepp-Logan filter resulted in better sensory, physical, and quantitative evaluations. The reconstruction conditions substantially improved the spatial resolution and visualization of the periodontal ligament space. The difference in sensitivity was obtained by altering the reconstruction filter.

Conclusion

Modifying the characteristics of a reconstruction filter can generate significant improvement in assessments of the periodontal ligament space. A high-frequency enhancement filter improves the visualization of thin structures and will be useful when accurate assessment of the periodontal ligament space is necessary.

Quality assurance in digital dental imaging: a systematic review

OBJECTIVES

Doses induced by individual dental examinations are low. However, dental radiography accounts for nearly one third of the total number of radiological examinations in the European Union. Therefore, special attention is needed with regard to radiation protection. In order to lower patient doses, the staff performing dental examinations must have competence in imaging as well as in radiation protection issues. This paper presents a systematic review about the core competencies needed by the healthcare staff in performing digital dental radiological imaging quality assurance.

MATERIALS AND METHODS

The following databases were searched: Pubmed, Cinahl, Pro Quest and IEEXplore digital library. Also volumes of some dental imaging journals and doctoral theses of the Finnish universities educating dentists were searched. The search was performed using both MeSH terms and keywords using the option 'search all text'. The original keywords were: dental imaging, digital, x-ray, panoramic, quality, assurance, competence, competency, skills, knowledge, radiographer, radiologist technician, dentist, oral hygienist, radiation protection and their Finnish synonyms.

RESULTS

Core competencies needed by the healthcare staff performing digital dental radiological imaging quality assurance described in the selected studies were: management of dental imaging equipment, competence in image quality and factors associated with it, dose optimization and quality assurance.

CONCLUSIONS

In the future there will be higher doses in dental imaging due to increasing use of CBCT and digital imaging. The staff performing dental imaging must have competence in dental imaging quality assurance issues found in this review. They also have to practice ethical radiation safety culture in clinical practice.

Comparison of cone-beam computerized tomography and intraoral radiographs for determination of the periodontal ligament in a variable phantom

OBJECTIVES

This in vitro study assessed the visualization quality of the periodontal ligament space in cone-beam computerized tomography (CBCT) compared with intraoral radiographs (CR).

STUDY DESIGN

A phantom mimicking variable periodontal ligament spaces (0-0.42 mm) was radiographed using CBCT and CR. Fifteen datasets of each modality were randomly mixed and presented twice to 19 experienced examiners and once to 19 inexperienced examiners.

RESULTS

Zero-millimeter gaps were recognized in 84.4% of CBCT and in 81.6% of CR images. On CBCT scans, gaps of 0.19 mm were identified with an accuracy of 93%-100% compared with 70.2%-81.7% using CR. Experienced examiners recognized gaps of >or=0.19 mm on CBCT repeatedly with nearly 100% accuracy.

CONCLUSION

Compared with CR, CBCT provides better visualization of simulated periodontal ligament space in this phantom.