Conventional Panoramic Imaging Research Articles

Factors influencing submandibular fossa visibility on panoramic images: a comparative CBCT study

ObjectiveThis study aimed to investigate the variables affecting the visibility of the submandibular fossa (SF) on panoramic images, including SF depth and types, age, gender, presence or absence of tooth, location of mandibular canal, and alveolar bone thicknesses.MethodsCone beam computed tomography (CBCT) images and conventional panoramic images of 150 patients were analyzed retrospectively. The visibility of the SF on panoramic images was compared with its depth and adjacent alveolar bone thicknesses on CBCT. Predictive variables affecting the SF visibility were identified, and binary logistic regression analysis was performed.ResultsBased on CBCT measurements, the SF depth was ≥ 2 mm in 65% of the hemi-mandibles with radiolucent area (26.7%). A significant difference was observed between the SF visibility on panoramic images and its depth, and the lingual cortical bone thickness as measured on CBCT. When the SF was visible and not, the mean SF depth was 2.24 ± 0.97 mm and 1.6 ± 0.8 mm, and lingual cortical bone thickness was 1.27 ± 0.47 mm and 1.53 ± 0.49, respectively. Regression analysis revealed significant associations between SF visibility and gender (Odds ratio (OR) = 3.28, 95% confidence interval (CI): 1.77–6.09), age (OR = 0.96, 95% CI: 0.94–0.98), SF depth (OR = 2.01, 95% CI: 1.43–2.81), and lingual cortical bone thickness (OR = 2.02, 95% CI: 1.30–3.16).ConclusionsA prominent radiolucent SF on panoramic images indicates a deeper fossa and thinner lingual cortical bone, necessitating caution by clinicians during surgical planning.

Detection of C-shaped mandibular second molars on panoramic radiographs using deep convolutional neural networks.

The C-shaped mandibular second molars (MSMs) may pose an endodontic challenge. The aim of this study was to develop a convolutional neural network (CNN)-based deep learning system for the diagnosis of C-shaped MSMs on panoramic radiographs. Panoramic radiographs and cone beam computed tomographic (CBCT) images were collected from a hospital in China and subsequently divided into two groups. In Group A, conventional panoramic images and CBCT images were derived from the same patients (n = 730 individuals), and the dataset consisted of conventional panoramic image patches of 1453 MSMs. In Group B (n = 610 individuals), the patients underwent CBCT examinations in the absence of available panoramic images; CBCT images were acquired and utilized to generate simulated panoramic images, and the dataset consisted of image patches of 1211 MSMs. Five pretrained CNN networks (ResNet-101 and - 50, DenseNet-121 and - 161, and Inception-V3) were utilized for the classification of C-shaped and non-C-shaped MSMs. Finally, the networks trained on the Group B dataset were tested on the Group A dataset. The diagnostic performance of each model was evaluated using receiver operating characteristic (ROC) curve analysis, and the CBCT images were taken as the gold standard. The results were compared with those achieved by three dental professionals. In Group A, all five networks exhibited satisfactory diagnostic performance, with AUC values ranging from 0.875 to 0.916 and accuracies ranging from 81.8 to 86.7%. No statistical differences were detected among the five CNNs. Notably, the models trained with Group B dataset (CBCT-generated panoramic images) achieved enhanced performance as tested on Group A dataset. The AUC values reached 0.984-0.996, and the accuracies ranged between 94.5% and 98.1%. CNNs outperformed dental professionals in classification performance, and the AUC values achieved by dental specialist, novice dentist, and dental graduate student were only 0.806, 0.767 and 0.730, respectively. CNN-based deep learning system demonstrated higher accuracy in the detection of C-shaped MSMs on panoramic radiographs compared to dental professionals. CBCT-generated panoramic images can serve as a substitute for conventional panoramic images in the training of CNN models when the quantity and quality of conventional panoramic image dataset is insufficient. CNN-based deep learning models have demonstrated significant potential in assisting dentists with the identification of C-shaped MSMs on panoramic radiographs, which facilitating more effective, efficient and safer dental treatment.

Spectral photon counting for panoramic dental imaging

Panoramic x-ray imaging is a versatile, low-dose imaging tool, which is routinely used for dental applications. In this work, we explore a further improvement of the concept by introducing recently developed spectral photon-counting detector technology into a conventional panoramic imaging unit. In addition we adapt spectral material decomposition algorithms to panoramic imaging needs. Finally, we provide first experimental results, demonstrating decomposition of an anthropomorphic head phantom into soft tissue and dentin basis material panoramic images, while keeping the noise level acceptable using regularization approaches. The obtained results reveal a potential benefit of spectral photon-counting technology also for dental imaging applications.

Comparison of Mesiodistal Root Angulation Measured from Conventional and CBCT Derived Panoramic Radiographs in Orthodontic Patients.

Introduction:Use of cone beam computed tomography (CBCT) in orthodontics is increasing; however, some patients started treatment with conventional images. The objective of this study is to manipulate CBCT panoramic reconstruction to make it comparable to conventional panoramic image and to compare mesiodistal root angulations on both images.Materials and Methods:Concurrent conventional panoramics and CBCT volumes were obtained from 40 subjects. CBCT volumes were manipulated to generate pan-like images that mimic the occlusal plane angle of the corresponding panoramic, allowing comparison of mesiodistal root angulations and determination of the head-tilt required to produce the reconstruction.Results:Clinically meaningful differences (p < .05) in the mesiodistal root angulations between standard panoramics and CBCT reconstructions emerged for 13 out of 24 teeth (54%). Greatest variations were seen in the maxillary and mandibular sextants and in first molar regions. Ideal axial head-tilt for image acquisition was determined to be with Frankfort horizontal plane 3.3o nose down.Conclusion:CBCT pan images must be used with caution due to variation between methods in specific areas of arches. The images can be useful for the assessment of mesiodistal root angulations if the volume is properly manipulated to create a pan-like image.

영상의 방향성을 이용한 ROI 기반 실시간 파노라마 영상 정합

본 논문은 임베디드 환경에서 실시간으로 동작하기 위해 입력 영상의 방향성을 판단하여 ROI를 지정하고 SURF, PROSAC 알고리즘을 적용하는 파노라마 영상 정합 방법을 제안한다. 기존의 파노라마 정합 알고리즘은 SURF 알고리즘이나 SIFT 알고리즘과 같이 많은 연산 데이터가 사용되는 알고리즘을 영상 전체에 적용하여 연산하기 때문에 불필요한 연산 영역을 포함하고 있다. 따라서 본 논문은 입력되는 영상의 방향을 판단한 결과로 영상의 ROI를 지정하여 불필요한 연산을 줄이는 방법을 제안한다. 영상의 방향을 판단하는데 사용하는 센서는 자이로 센서와 가속도 센서를 사용한다. 임베디드 환경에서 자이로 센서와 가속도 센서의 상보 필터를 통한 값 보정은 영상 정합 알고리즘의 처리 시간에 영향을 주지 않기 때문에 실시간 동작이 가능하다. In this paper, we proposed an implementation of panoramic image stitching that operates in real time at the embedded environment by applying ROI based PROSAC algorithm using the directionality of the image. The conventional panoramic image stitching applies SURF or SIFT algorithm which contains unnecessary computation and a lots of data to detect feature points. In this paper, we use the direction of the input image and we proposed the method of reducing the unnecessary computation by using ROI. We use a gyro sensor and an acceleration sensor. Output data from gyro and acceleration sensors can be calibrated by complementary filter. The calibration does not affect the operating time of the proposed image stitching algorithm in embedded environment. Therefore, it is possible to operate in real-time.

ROI 기반 실시간 이미지 정합 알고리즘 구현

본 논문은 임베디드 환경에서 실시간으로 동작하기 위해 이미지에 ROI를 지정하고 PROSAC 알고리즘을 적용하여 구현한 파노라마 영상 정합을 제안한다. 기존의 방식은 SURF 알고리즘이나 SIFT 알고리즘과 같이 복잡한 연산과 많은 연산 데이터의 알고리즘을 화면 전체에 적용하여 탐색한다. 또한 outlier 제거 알고리즘으로 RANSAC을 적용하여 알고리즘이 가진 무작위성으로 추가적인 검증 시간을 필요로 한다. 본 논문은 파노라마 영상의 특성을 고려하여 ROI를 설정함으로써 불필요한 연산량을 줄이고 outlier 제거 알고리즘을 검증 시간을 줄인 PROSAC 알고리즘으로 채택하여 처리 속도를 개선하였다. 비교 실험은 ARM Cortex-A15가 내장된 ODROID-XU 환경에서 진행 하였다. 제안하는 방식은 기존의 방식보다 처리 시간이 약 54% 개선되었다. This paper proposes a panoramic image stitching that operates in real time at the embedded environment by applying ROI and PROSAC algorithm. The conventional panoramic image stitching applies SURF or SIFT algorithm which contains complicated operations and a lots of data, at the overall image to detect feature points. Also it applies RANSAC algorithm to remove outliers, so that an additional verification time is required due to its randomness. In this paper, unnecessary data are eliminated by setting ROI based on the characteristics of panorama images, and PROSAC algorithm is applied for removing outliers to reduce verification time. The proposed method was implemented on the ORDROID-XU board with ARM Cortex-A15. The result shows an improvement of about 54% in the processing time compared to the conventional method.

Virtual Viewpoint Three-Dimensional Panorama

Conventional panoramic images are known to provide for an enhanced field of view in which the scene always has a fixed appearance. The idea presented i n this paper focuses on the use of the concept of v irtual viewpoint creation to generate different panoramic images of the same scene with three-dimensional component. Three-dimensional effect in a resultant panorama is realized by superimposing a stereo-pair of panoramic images.

Evaluation of panoramic image quality in three images system.

In vitro study to evaluate the diagnostic image quality of dental panoramic radiography by comparing between conventional and digital systems. Aim of the Study: The aim of this study was to compare and evaluate the image quality of panoramic radiograph. Material and Method: Study comparing the image quality of dental Panoramic between conventional and digital in three dental institutions diagnostic imaging department. Forty five panoramic image were collected and divided in to three groups consisting of conventional images obtained with STRATO 2000, CE by VILLA SISTEMI MEDICALI–ITALY (screen based film) Dimax3digital system pan/ceph, PLANMECA, Helsinki, Finland, and Kodak 8000 carestream health, France (CCD X–ray image sensor). Image quality was assessed by rating the visibility of three evaluation aspect commonly found on panoramic radiographs for each image Depending on three evaluation aspect which is include the anatomy coverage, contrast and density of the teeth and anatomical structure, high score representing better image quality and the lower score indicating poor image quality. Results: the data collected from the evaluation of digital and film based image by two examiner were analyzed by chi square and the difference was statistically significant. Conclusion: The highest quality scores were obtained with carestream health digital system whereas images from Dimax3 digital system and conventional panoramic image type by VILLA SISTEMI were ranked significantly lower.

A Comparison of Panoramic Image Quality between a Digital Radiography Storage Phosphor System and a Film-Based System

To compare digital panoramic images acquired for the presurgical assessment of third molars captured with a storage phosphor-based system with conventional film panoramic radiographs. A total of 51 pairs of digital and conventional panoramic images, made simultaneously, were included in this study. The images were evaluated for diagnostic quality prior to third molar surgery by two experienced oral surgeons and rated with a four-point grading scale. Despite the fact that conventional panoramic images were rated higher than the digital images, the difference was not statistically significant. Conventional and digital panoramic images were found to be of comparable image quality with regard to their diagnostic contribution to third molar surgery. This study is contributory to understanding differences in image quality between digital and conventional panoramic radiography for certain diagnostic tasks. The lack of significant differences in image quality may be an endorsement for digital panoramic radiography.

Quasi-Feature based Panoramic Video Creation for Multiview Object Tracking System

In this paper we present an efficient approach to building a panoramic video from mutiview cameras and to tracking objects. The proposed panoramic video creation module consists of two functions: (i) selecting four quasi-feature points in two adjacent frames acquired by corresponding multiple cameras and (ii) mosaicing the two images. Four pairs of selected quasi-feature points play a role of similarity reference in registering two adjacent frames. The mosaicing step uses the direct linear transformation (DLT) algorithm. The proposed tracking algorithm uses the active contour model (ASM), which is robust against partial occlusion. The proposed tracking module consists of four functions: (i) landmark point assignment, (ii) principal component analysis (PCA), (iii) modeling of local structure, and (iv) model fitting. While most conventional panoramic image creation methods are pixel-based, the proposed feature-based method provides more accurate tracking result. In the experiment, the created panoramic images exhibit high quality, which enables robust, real-time video tracking.

Panoramic radiographic findings as predictors of mandibular nerve exposure following third molar extraction: Digital versus conventional radiographic techniques

The aim was to compare digital and conventional panoramic imaging techniques for identifying high-risk radiographic markers associated with mandibular nerve (MN) injury after mandibular third molar (M3) removal. The study used a retrospective cohort model. The predictor variable was the presence or absence of radiographic signs associated with MN exposure during M3 removal. The outcome variable was MN exposure. Intraexaminer variability was estimated using a kappa statistic. Logistic regression modeling was used to measure the association between radiographic signs and MN exposure and determine if imaging technique modified that association. The level of statistical significance was set at P < .05. The sample was composed of 571 patients having 1,017 mandibular M3s removed. The MN was visualized in 66 extraction sites (6.5%). In the adjusted logistic model, radiographic signs were statistically associated with MN exposure (P < .001) and imaging technique was a statistically insignificant effect modifying variable (P = .4). The results of this study suggest that imaging technique does not modify the relationship between high-risk panoramic radiographic signs and MN exposure.

Dosimetry of 3 CBCT devices for oral and maxillofacial radiology: CB Mercuray, NewTom 3G and i-CAT

Cone beam computed tomography (CBCT), which provides a lower dose, lower cost alternative to conventional CT, is being used with increasing frequency in the practice of oral and maxillofacial radiology. This study provides comparative measurements of effective dose for three commercially available, large (12'') field-of-view (FOV), CBCT units: CB Mercuray, NewTom 3G and i-CAT. Thermoluminescent dosemeters (TLDs) were placed at 24 sites throughout the layers of the head and neck of a tissue-equivalent human skull RANDO phantom. Depending on availability, the 12'' FOV and smaller FOV scanning modes were used with similar phantom positioning geometry for each CBCT unit. Radiation weighted doses to individual organs were summed using 1990 (E(1990)) and proposed 2005 (E(2005 draft)) ICRP tissue weighting factors to calculate two measures of whole-body effective dose. Dose as a multiple of a representative panoramic radiography dose was also calculated. For repeated runs dosimetry was generally reproducible within 2.5%. Calculated doses in microSv [corrected] (E(1990), E(2005 draft)) were NewTom3G (45, 59), i-CAT (135, 193) and CB Mercuray (477, 558). These are 4 to 42 times greater than comparable panoramic examination doses (6.3 microSv [corrected] 13.3 mSv). Reductions in dose were seen with reduction in field size and mA and kV technique factors. CBCT dose varies substantially depending on the device, FOV and selected technique factors. Effective dose detriment is several to many times higher than conventional panoramic imaging and an order of magnitude or more less than reported doses for conventional CT.

A comparison of conventional panoramic radiographs with volumetric computed tomography images in the preoperative assessment of impacted mandibular third molars

Purpose: In the present study, we evaluated the geometric, topographic, and anatomic reliability of volumetric computed tomography (VCT) images by comparing conventional panoramic radiographs with reconstructed VCT panoramic and paraxial images before performing third molar surgery. Patients and Methods: A total of 6 anatomic sites on 10 patients who showed a topographic relationship between the apices of the third molar root and the mandibular canal were preoperatively assessed by 5 oral surgeons using conventional panoramic radiographs; these were complemented and compared with secondary reconstructed paraxial and panoramic VCT images. Results: The position of the apices in relation to the mandibular canal could be revealed on 94% of VCT reconstructed paraxial images. Assessment of VCT paraxial images could be facilitated by using a toolbar marker in 70% of the paraxial images. In 90% of the paraxial images, it was possible to assess the relationship of the mandibular canal and its adjacent anatomy. The visual grading scores for conventional panoramic images were significantly better on all 7 assessed anatomic sites compared with the reconstructed VCT panoramic images. Conclusion: The results showed that the VCT paraxial images gave a significantly clearer perception of the mandibular nerve than conventional panoramic radiographs. However, conventional panoramic radiographs were shown to be better than the VCT reconstructed panoramic images and were therefore an invaluable tool in the “expert-derived” assessment and posed the potential for identifying the need for further VCT diagnostic procedures. © 2002 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg 60:979-984, 2002