Subjective image quality of solid-state and photostimulable phosphor systems for digital intra-oral radiography

OBJECTIVES: To compare subjectively the image quality of intra-oral radiographs from six digital systems. METHODS: Two generations of two different solid-state detectors; Visualix-1 and -2 (Gendex Dental Systems, Milan, Italy), Computed Dental Radiography (CDR) and CDR Active Pixel Sensor (APS) (Schick Technologies Inc., Long Island City, NY, USA), and two photostimulable phosphor (PSP) systems; Digora (Soredex, Orion Corporation, Helsinki, Finland) and DenOptix (Gendex Dental Systems, Milan, Italy) were compared. Tooth-containing specimens from different areas of dried mandibles were radiographed at exposures between 91-9400 microGy. Images were transferred to a personal computer, displayed in random order and evaluated in their original form and after applying a histogram equalisation algorithm. Eight observers graded subjective image quality using a 5-point scale. RESULTS: Both CDR systems scored highest for image quality but within the narrowest exposure range. The Visualix images received the lowest scores. The PSP systems produced acceptable image quality at both lower and higher exposures than the solid-state systems. Enhanced images were generally considered to be inferior to the original images, except for those produced by the four solid-state systems at very low exposures. CONCLUSIONS: (i) the PSP systems provided a clinically acceptable image quality over a wide exposure range; (ii) the CDR systems had the best image quality but over the narrowest exposure ranges; (iii) the Visualix systems had the lowest image quality; and (iv) histogram equalisation did not generally improve image quality.     

Accuracy of scanography using storage phosphor plate systems and film for assessment of mandibular third molars

Objectives

The aim of this study was to compare the diagnostic accuracy of two digital photostimulable storage phosphor (PSP) systems and film for assessment of mandibular third molars before surgery.

Methods

110 patients were referred to have both their mandibular third molars removed. Each patient underwent a radiographic examination with scanography using either Digora (Soredex, Helsinki, Finland) and film or VistaScan (Dürr Dental, Beitigheim-Bissingen, Germany) and film in a randomized paired design. Two observers examined the following variables on the scanograms: bone coverage, angulation of the tooth in the bone, number of roots, root morphology and the relationship to the mandibular canal. In 75 of the pairs (Digora/film pair = 38 and Vista/film pair = 37) both third molars were eventually removed. During and after surgery the same variables were assessed, which served as reference standard for the radiographic assessments. The Wilcoxon signed-rank test tested differences in accuracy (radiographic compared with surgical findings) between Digora/film and between Vista/film.

Results

There was no statistically significant difference between the diagnostic accuracy of film and either of the two digital receptors for assessment of mandibular third molars before surgery (P > 0.05), although Digora obtained a higher accuracy than film.

Conclusions

Scanography is a valuable method for examination of mandibular third molars before removal and the PSP digital receptors in this study were equal to film for this purpose.     

Image and surgery-related costs comparing cone beam CT and panoramic imaging before removal of impacted mandibular third molars

Objectives:

The aim of this prospective clinical study was to derive the absolute and relative costs of cone beam CT (CBCT) and panoramic imaging before removal of an impacted mandibular third molar. Furthermore, the study aimed to analyse the influence of different cost-setting scenarios on the outcome of the absolute and relative costs and the incremental costs related to surgery.

Methods:

A randomized clinical trial compared complications following surgical removal of a mandibular third molar, where the pre-operative diagnostic method had been panoramic imaging or CBCT. The resources implied in the two methods were measured with health economic tools. The primary outcome was total costs defined as the sum of absolute imaging costs and incremental surgery-related costs. The basic variables were capital costs, operational costs, radiological costs, radiographic costs, overheads and patient resource utilization. Differences in resources used for surgical and post-surgical management were calculated for each patient.

Results:

Converted to monetary units, the total costs for panoramic imaging equalized €49.29 and for CBCT examination €184.44. Modifying effects on this outcome such as differences in surgery time, treatment time for complications, pre- and post-surgical medication, sickness absence, specialist treatment and hospitalization were not statistically significant between the two diagnostic method groups.

Conclusions:

Costs for a CBCT examination were approximately four times the costs for panoramic imaging when used prior to removal of a mandibular third molar. The use of CBCT did not change the resources used for surgery, post-surgical treatment and patient complication management.     

Time and motion study: a comparison of two photostimulable phosphor imaging systems used in dentistry

OBJECTIVES: To compare two photostimulable phosphor (PSP) dental radiographic systems in terms of time efficiency in making full mouth intraoral X-ray surveys (FMS). METHODS: PSP systems compared were (1) DenOptix) (Kavo/Gendex, Des Plaines, IL) and (2) ScanX) (Air Techniques, Hicksville, NY). Twenty one FMS of a DXTRR) Manikin (Dentsply, Des Plaines, IL) were made with each of the systems. Time for each procedural step was determined using a stopwatch. Steps studied were: (1) plate erasure; (2) packaging; (3) positioning/exposure; (4) unpacking, loading processor, scanning; and (5) image transfer to virtual FMS mount. The first six test runs for each system were excluded to eliminate the learning curve period influencing results. An independent groups t-test was employed for statistical analysis. The a priori was set at P< or =0.05. RESULTS: The total time involved in producing a FMS was not proven to be statistically significant comparing DenOptix) and ScanX). The mean procedure time for DenOptix) was 31.2 min; for ScanX) it was 27.1 min. While the processing time with ScanX) (mean time: 3.9 min) was shorter than for DenOptix) (mean time =7.8 min), the opposite was true for the image transfer to FMS format with the time much shorter with DenOptix) using VixWin) software (mean time =2.0 min) compared with ScanX) using Vipersoft) (mean time =3.9 min). The differences between the systems for these two steps did prove to be statistically significant (P< or =0.05). CONCLUSIONS: Although the mean time to make a FMS was slightly shorter on average with ScanX) than DenOptix), this difference was not proven to be statistically significant (P>0.05) in terms of time efficiency in producing a FMS.     

左旋布比卡因在下颌阻生智齿拔除术中麻醉效果及术后镇痛作用研究

 目的 观察左旋布比卡因在下颌阻生智齿拔除术中的麻醉效果及术后镇痛作用.方法 选择需拔除双侧下颌阻生智齿34例,采用交叉试验方法,分别使用0.5%左旋布比卡因及2%利多卡因进行下齿槽神经麻醉,观察麻醉药起效时间.采用VAS评分法对两组麻醉效果进行评定,并对术后患者服用镇痛药(芬必得胶囊)情况进行记录.结果 0.5%左旋布比卡因及2%利多卡因麻醉药起效时间分别为(6.59±2.20)min和(4.40±1.43)min,两组差异具有统计学意义(P<0.05);左旋布比卡因组术中VAS评分低于利多卡因组,两组差异具有统计学意义(P<0.05);左旋布比卡因组术后服用镇痛药人数为3人,明显少于利多卡因组16人,差异具有统计学意义(P<0.01).结论 采用左旋布比卡因行下齿槽神经阻滞麻醉拔除下颌阻生智齿,术中麻醉有效,术后镇痛作用较好.     

Image quality, lesion detection, and diagnostic efficacy in digital mammography: full-field digital mammography versus computed radiography-based mammography using digital storage phosphor plates

OBJECTIVE: To compare image quality, the lesion detection, and the diagnostic efficacy of full-field digital mammography (FFDM) and computed radiography-based mammography using digital storage phosphor plates (DSPM) in the evaluation of breast lesions. MATERIALS AND METHODS: In this prospective study, 150 patients with suspicious breast lesions underwent FFDM and DSPM. Nine aspects of image quality (brightness, contrast, sharpness, noise, artifacts, and the detection of anatomic structures, i.e., skin, retromamillary space, glandular tissue, and calcifications) were evaluated by five radiologists. In addition, the detection of breast lesions and the diagnostic efficacy, based on the BI-RADS classification, were evaluated with histologic and follow-up correlation. RESULTS: For contrast, sharpness, and the detection of all anatomic structures, FFDM was rated significantly better (p<0.05). Mass lesions were equally detected, whereas FFDM detected more lesions consisting of calcifications (85 versus 75). DSPM yielded two false-negative results. Both lesions were rated BI-RADS 4 with FFDM, but BI-RADS 2 with DSPM. Both were invasive carcinoma at histology. The sensitivity, specificity, PPV, NPV, and accuracy of FFDM were 1.0, 0.397, 0.636, 1.0, and 0.707, compared to 0.974, 0.397, 0.630, 0.935, and 0.693 of DSPM. CONCLUSION: Based on image quality parameters, FFDM is, in part, significantly better than DSPM. Furthermore, the detection of breast lesions with calcifications is favorable with FFDM. However, the diagnostic efficacy of FFDM and DSPM was equal. The interpretation of the false-negative results suggests that the perception and characterization of breast lesions is not defined solely by the digital mammography system but is strongly influenced by the radiologist, who is one of the determinants in the interpretation of breast imaging.     

Economic and health implications of routine CBCT examination before surgical removal of the mandibular third molar in the Danish population

Objectives:

This epidemiological study aimed to analyse economical and societal consequences in Denmark if CBCT is used routinely as a diagnostic method before removal of the mandibular third molar. Furthermore, the aim was to calculate the excess cancer incidence from this practice.

Methods:

17 representative dental clinics in the regions of Denmark were visited by two observers, who registered the total number of patients in each clinic, the number of removed mandibular third molars from patients'' files together with the age and gender of these patients. The data were collected from 2008 to 2014. The total number of removed mandibular third molars in Denmark each year was derived from the collected data and information on patients'' contacts with dentists from Statistics Denmark as a sum of contributions from each region. The contribution of a region was obtained as the number of removed mandibular third molars in the selected clinics in the region times the ratio of the number of patients in the selected clinics in the region to the total number of patients with contact to a general practitioner in the region in 2011. Existing knowledge on the costs for panoramic and CBCT imaging was used to calculate total costs. The cancer incidence was calculated from lifetime attributable risk curves based on linear risk assumptions.

Results:

The selected clinics included 109,686 patients, and 1369 mandibular third molars had been surgically removed. Using data from Statistics Denmark gave an estimated annual number of removed mandibular third molars of 36,882 at a total cost of €6,633,400. The additional cancer incidence was estimated to be approximately 0.46 per year.

Conclusions:

The data should be used in a cost-effectiveness analysis of the clinical efficacy of CBCT imaging before removal of mandibular third molars.     

Accuracy of digital and film panoramic radiographs for assessment of position and morphology of mandibular third molars and prevalence of dental anomalies and pathologies

OBJECTIVES: To compare the accuracy of digital and film panoramic radiographs for determining (1) the position and morphology of mandibular third molars before surgical removal and (2) the prevalence of dental anomalies and pathologies. METHODS: Three hundred and eighty-eight third mandibular molars were available for examination. Position and morphology of third molars observed on film radiographs and on digital panoramic images from five systems (DenOptix, DigiDent, Digora, Dimax2 and Orthophos Plus) were recorded by two observers and were compared with surgeons' findings at the time of the operation (gold standard). One observer further recorded the prevalence of dental anomalies and pathologies on both imaging modalities. RESULTS: Few differences were found between the digital and film-based panoramic systems in the assessment of accuracy of position and morphology of mandibular third molars. The prevalence of dental anomalies and pathologies determined with the two modalities was roughly similar. CONCLUSION: The five digital panoramic systems evaluated in this study were equally as useful for third molar treatment planning and diagnosis of dental anomalies and pathologies as conventional film-based panoramic radiographs.     

Image quality of digital mammography images produced using wet and dry laser imaging systems

IntroductionA study was carried out to compare the quality of digital mammographic images printed or processed by a wet laser imaging system and a dedicated mammographic dry laser imaging system.Material and methodsDigital images of a tissue equivalent breast phantom were obtained using a GE Senographe 2000D digital mammography system and different target/filter combinations of the X-ray tube. These images were printed on films using the Fuji FL-IM D wet laser imaging system and the Kodak DryView 8600 dry laser imaging system. The quality of images was assessed in terms of detectability of microcalcifications and simulated tumour masses by five radiologists. In addition, the contrast index and speed index of the two systems were measured using the step wedge in the phantom. The unpaired, unequal variance t-test was used to test any statistically significant differences.ResultsThere were no significant (p < 0.05) differences between the images printed using the two systems in terms of microcalcification and tumour mass detectability. The wet system resulted in slightly higher contrast index while the dry system showed significantly higher speed index.ConclusionBoth wet and dry laser imaging systems can produce mammography images of good quality on which 0.2 mm microcalcifications and 2 mm tumour masses can be detected. Dry systems are preferable due to the absence of wet chemical processing and solid or liquid chemical waste. The wet laser imaging systems, however, still represent a useful alternative to dry laser imaging systems for mammography studies.     

Ability of two radiographic methods to identify the closeness between the mandibular third molar root and the inferior alveolar canal: a pilot study

Objectives

The aim was to compare the ability of two radiographic methods: the panoramic radiograph (PR) in combination with a 20-degree negative angle periapical radiograph (−20°Pa) vs two periapical radiographs Pa + (−20°Pa), in evaluating the closeness of the lower third molar root and the inferior alveolar canal.

Methods

2 radiographic methods of 32 impacted third molars were used. Two untrained dental students evaluated the closeness of the association between the root tip of the lower third molar and the inferior alveolar canal, both when in contact and separated, using dental cone beam CT as the gold standard. The position of the inferior alveolar canal relative to the third molar root was also recorded. The sensitivities and specificities of these findings were evaluated. Kappa values were used to assess the intra- and interobserver reliability.

Results

Of the 32 teeth, 23 (68.6%) showed contact between the root tip of the third molar and the inferior alveolar canal on dental cone beam CT, and 9 (31.4%) showed separation. The respective mean sensitivities of PR + (−20°Pa) and Pa + (−20°Pa) in detecting contact were 97.9% and 84.8% and the respective mean specificities in detecting separation were 16.7% and 44.4%. Intraobserver agreement in both techniques ranged from 0.69 to 0.94. The respective interobserver reliability was 0.88 in PR + (−20°Pa) and 0.75 in Pa + (−20°Pa).

Conclusions

Both the PR + (−20°Pa) and the periapical vertical tube-shift technique Pa + (−20°Pa) have high potential for detecting the closeness between the third molar root and the inferior alveolar canal.     

Image quality, diagnostic certainty, and accuracy: comparison of conventional and digital urograms

Our previous research showed that radiologists could interpret digital urograms with sensitivity, specificity, and receiver operating characteristic (ROC) curve performance similar to their interpretations of conventional urograms. To evaluate further the suitability of digital radiology for performing excretory urography, we investigated relationships among image quality, radiologists' certainty of diagnostic decisions, and diagnostic accuracy for digital and conventional urograms. We examined data from a study of 100 excretory urograms performed using matched film-screen and digital exposures. Three radiologists rated the quality of digital urographic images compared to film-screen images. Image quality did not correlate well with diagnostic accuracy for either modality, perhaps because of the overall high level of quality of the exposures. Radiologists' level of certainty in their diagnostic decisions decreased with poorer image quality for both modalities. The similarities of the tested relationships provides further evidence that digital technology is suitable for use in urography.     

Image quality,diagnostic certainty,and accuracy: Comparison of conventional and digital urograms

Our previous research showed that radiologists could interpret digital urograms with sensitivity, specificity, and receiver operating characteristic (ROC) curve performance similar to their interpretations of conventional urograms. To evaluate further the suitability of digital radiology for performing excretory urography, we investigated relationships among image quality, radiologists’ certainty of diagnostic decisions, and diagnostic accuracy for digital and conventional urograms. We examined data from a study of 100 excretory urograms performed using matched film-screen and digital exposures. Three radiologists rated the quality of digital urographic images compared to film-screen images. Image quality did not correlate well with diagnostic accuracy for either modality, perhaps because of the overall high level of quality of the exposures. Radiologists’ level of certainty in their diagnostic decisions decreased with poorer image quality for both modalities. The similarities of the tested relationships provides further evidence that digital technology is suitable for use in urography.     

Experimental investigations of image quality in X-ray mammography with conventional screen film system (SFS), digital phosphor storage plate in/without magnification technique (CR) and digital CCD-technique (CCD)

Comparison of image quality in X-ray mammography between conventional film screen film system (SFS), digital phosphor storage plate in and without magnification technique (CR) and digital CCD-technique (CCD). Radiograms of an RMI-mammography phantom were acquired using a conventional screen film system, three digital storage plate systems and two digital systems in CCD-technique. Additionally, the radiograms of one digital phosphor storage plate system were post-processed regarding contrast and included in the comparison. The detectability of details was best with the digital mammography in CCD-technique. After confirming these promising results in clinical studies, digital mammography should be able to replace conventional screen film technique.     

Radiation dose and image quality of X-ray volume imaging systems: cone-beam computed tomography, digital subtraction angiography and digital fluoroscopy

Objective

Radiation dose and image quality estimation of three X-ray volume imaging (XVI) systems.

Methods

A total of 126 patients were examined using three XVI systems (groups 1–3) and their data were retrospectively analysed from 2007 to 2012. Each group consisted of 42 patients and each patient was examined using cone-beam computed tomography (CBCT), digital subtraction angiography (DSA) and digital fluoroscopy (DF). Dose parameters such as dose–area product (DAP), skin entry dose (SED) and image quality parameters such as Hounsfield unit (HU), noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were estimated and compared using appropriate statistical tests.

Results

Mean DAP and SED were lower in recent XVI than its previous counterparts in CBCT, DSA and DF. HU of all measured locations was non-significant between the groups except the hepatic artery. Noise showed significant difference among groups (P?<?0.05). Regarding CNR and SNR, the recent XVI showed a higher and significant difference compared to its previous versions. Qualitatively, CBCT showed significance between versions unlike the DSA and DF which showed non-significance.

Conclusion

A reduction of radiation dose was obtained for the recent-generation XVI system in CBCT, DSA and DF. Image noise was significantly lower; SNR and CNR were higher than in previous versions. The technological advancements and the reduction in the number of frames led to a significant dose reduction and improved image quality with the recent-generation XVI system.

Key Points

? X-ray volume imaging (XVI) systems are increasingly used for interventional radiological procedures. ? More modern XVI systems use lower radiation doses compared with earlier counterparts. ? Furthermore more modern XVI systems provide higher image quality. ? Technological advances reduce radiation dose and improve image quality.     

Influence of cone beam CT on treatment plan before surgical intervention of mandibular third molars and impact of radiographic factors on deciding on coronectomy vs surgical removal

Objectives

To assess the influence of cone beam CT (CBCT) on treatment plan before surgical intervention of mandibular third molars and to identify radiographic factors with an impact on deciding on coronectomy.

Methods

186 mandibular third molars with an indication for surgical intervention underwent a radiographic examination with two methods: (1) panoramic imaging in combination with stereo-scanography and (2) CBCT. After the radiographic examination a treatment plan (TP) was established: either surgical removal (Sr) or coronectomy (Co). The first TP was based on the panoramic image and stereo-scanogram, while the second TP was established after CBCT was available. Logistic regression analyses were used to identify factors predisposing for Co after CBCT.

Results

Treatment was performed according to the second TP. Agreement between the first and second TP was seen in 164 cases (88%), while the TP changed for 22 teeth (12%) after CBCT. Direct contact between the third molar and the mandibular canal had the highest impact on deciding on Co [odds ratio (OR) = 101.8, p < 0.001]. Direct contact was not a sufficient factor, however; thus, lumen narrowing of the canal (OR = 38.9–147.2, p < 0.001) and canal positioned in a bending or a groove in the root complex (OR = 32.8, p = 0.016) were additional canal-related factors for deciding on Co.

Conclusion

CBCT influenced the treatment plan for 12%. Direct contact in combination with narrowing of the canal lumen and canal positioned in a bending or a groove in the root complex observed in CBCT images were significant factors for deciding on coronectomy.     

Paresthesia of the inferior alveolar nerve following the extraction of the mandibular third molars: a literature review of its causes, treatment, and prognosis.

Mandibular paresthesia is an unfortunate complication after the extraction of mandibular third molars. Damage to the inferior alveolar nerve may occur via direct or indirect injury. Careful evaluation of pre-operative panoramic radiographs with regard to root configuration and intimacy to the mandibular canal are most important. Various surgical techniques may be dictated by the radiographic presentation. When paresthesia does occur, a simple yet thorough mechanism for documentation is required. This article reviews paresthesia of the inferior alveolar nerve as a result of the extraction of the mandibular third molars.     

乳腺数字化X线射影术、计算机X线射影术和屏-胶片系统影像质量和放射剂量的比较

目的 比较增感屏-胶片乳腺X线摄影、数字乳腺摄影(DR)和计算机乳腺摄影(CR)3种系统的模体影像质量、辐射剂量和临床对疾病诊断的准确率.方法 选择3台临床使用中的屏-胶片、DR和CR乳腺摄影设备,进行性能测试,确保质量符合规定,具有可比性.以屏-胶片系统的辐射剂量为标准,使用DR和CR分别对Manuno-152模体和美国放射学院(ACR)模体摄影.再使用DR和CR的最优模式对模体摄影并记录辐射剂量.所获图像照片按模拟病变结构编号,由8名专业乳腺放射学医师在相同条件下分别进行ACR评分.3种方法的评分结果采用随机区组设计的方差分析进行统计学处理.连续收集一段时期内采用3种检查方法检查,并且有病理诊断结果的患者的影像资料,应用Kappa检验方法进行2种诊断结果一致性检验,并以病理结果为金标准,比较3种影像检查结果诊断的准确率.结果 对于Mammo-152模体,无论DR、CR的辐射剂量是否超过屏一胶片乳腺X线摄影的2.25 mGy乳腺平均剂量,屏-胶片摄影的空间分辨率都最高(7.0～8.0 Lp/mm),DR次之(4.7～5.2 Lp/mm),CR最差(2.5 Lp/mm).增加辐射剂量(27.0%～30.0%),DR的空间分辨率略有改善(上升11.0%),而CR几乎没有改变(上升1.5%).对ACR模体摄影时,DR的辐射剂量没有超过屏-胶片乳腺X线摄影的2.22 mGy乳腺平均剂量,且模拟结构显示度最好.屏-胶片乳腺x线摄影的团块显示优于CR,但CR的纤维和点阵显像优于屏-胶片乳腺X线摄影.CR检查时辐射剂量提高25.0%,纤维和点阵显像接近DR,团块显像接近屏-胶片乳腺x线摄影.3台设备的X线诊断和病理诊断结果的一致性极好(屏-胶片系统的一致率50/56,DR系统83/90,CR系统61/69,P值均<0.01且Kappa值均>0.75),在疾病诊断准确率上差异没有统计学意义[屏-胶片系统的准确率为89.3%(50/56),DR系统为92.2%(83/90),CR系统为88.4%(61/69),PearsonX2值为0.722,P=0.697].结论 屏-胶片乳腺X线摄影分辨率最高,DR的模拟病变显像最好且辐射剂量最低.当CR的辐射剂量与屏-胶片乳腺X线摄影相当时,两者对模拟病变的显像各有优劣;当增加CR的摄影剂量时,其模拟结构显像质量高于屏-胶片乳腺X线摄影,低于DR.在临床对疾病的诊断准确率方面,三者无明显差别.