Journal of X-Ray Science and Technology - Volume 28, issue 4

Authors: Niu, Shanzhou | Lu, Shaohui | Zhang, You | Huang, Xiaokun | Zhong, Yuncheng | Yu, Gaohang | Wang, Jing

Article Type: Research Article

Abstract: BACKGROUND: Triple-energy computed tomography (TECT) can obtain x-ray attenuation measurements at three energy spectra, thereby allowing identification of different material compositions with same or very similar attenuation coefficients. This ability is known as material decomposition, which can decompose TECT images into different basis material image. However, the basis material image would be severely degraded when material decomposition is directly performed on the noisy TECT measurements using a matrix inversion method. OBJECTIVE: To achieve high quality basis material image, we present a statistical image-based material decomposition method for TECT, which uses the penalized weighted least-squares (PWLS) criteria with total …variation (TV) regularization (PWLS-TV). METHODS: The weighted least-squares term involves the noise statistical properties of the material decomposition process, and the TV regularization penalizes differences between local neighboring pixels in a decomposed image, thereby contributing to improving the quality of the basis material image. Subsequently, an alternating optimization method is used to minimize the objective function. RESULTS: The performance of PWLS-TV is quantitatively evaluated using digital and mouse thorax phantoms. The experimental results show that PWLS-TV material decomposition method can greatly improve the quality of decomposed basis material image compared to the quality of images obtained using the competing methods in terms of suppressing noise and preserving edge and fine structure details. CONCLUSIONS: The PWLS-TV method can simultaneously perform noise reduction and material decomposition in one iterative step, and it results in a considerable improvement of basis material image quality. Show more

Keywords: Triple-energy CT, image-based material decomposition, penalized weighted least-squares, total variation

DOI: 10.3233/XST-200672

Citation: Journal of X-Ray Science and Technology, vol. 28, no. 4, pp. 751-771, 2020

Authors: Li, Kuei-Liang | Lin, Jao-Perng | Chen, Yi-Ching | Lu, Chia-Chun

Article Type: Research Article

Abstract: During radiotherapy for head and neck tumours, the oral cavity and cheek area would be inevitably exposed to high energy radiation; thus, the material surface of the teeth, dental restorations with high atomic number, or alloy prosthodontics would generate backscatter electrons that cause the buccal mucosa adjacent to these materials to receive localized high dose enhancement, which primarily leads to side effects or oral mucositis. Based on the size of the adult oral cavity, this study aimed to use acrylic resin to create an oral phantom with two grooves on the left and right sides for placement of three molars. …Moreover, the distance between the inner cheek and the side surface of the teeth could be accurately adjusted every 1 mm from 0 to 5 mm. This enhanced the dose in the buccal mucosa during head and neck radiotherapy and made the distribution measurement of the radiation dose simple and feasible at different depths (0–5 mm). Meanwhile, the study employed the film type optically stimulated luminescent dosimeter with a thickness of 0.3 mm to measure the absorbed dose inside the buccal mucosa to reduce the dose interference from radiotherapy. The study fixed three real molars in a row located at the left side of the phantom and employed 6 MV photons and intensity-modulated radiotherapy (IMRT) to treat and simulate oral cancer and measure the attenuation of the molar’s backscatter dose from 0 to 5 mm in an up beam direction. The result showed that, in every 3 mm, the phantom had attenuated the enhancement of backscatter dose <3%. The irradiation dose enhancement in a single direction was twice higher than that through IMRT 7 field treatment. These measurement results were consistent with the results of previous studies. Show more

Keywords: Oral cavity, backscatter dose, dental restoration, mucositis, optically stimulated luminescent dosimeter

DOI: 10.3233/XST-200664

Citation: Journal of X-Ray Science and Technology, vol. 28, no. 4, pp. 773-782, 2020

Authors: Ming, Ye | Hu, Yun | Wang, Tao | Zhang, Jiangtao | Li, Yuyue | Xu, Wenjie | Tan, Hao | Ye, Huayu | Zheng, Leilei

Article Type: Research Article

Abstract: OBJECTIVE: To evaluate skeletal and dental changes in patients with skeletal Class III malocclusion and facial asymmetry after surgical-orthodontic treatment using cone-beam computerized tomography (CBCT). METHODS: This study included forty adult patients diagnosed with skeletal Class III malocclusion and asymmetry who underwent either isolated mandibular surgery or bimaxillary surgery. CBCT scans were taken before treatment (T0), at the completion of presurgical orthodontic treatment (T1) and after treatment (T2). Mimics 17.0 and 3-Matics 7.0 were used to measure skeletal and dental parameters. Skeletal and dental changes within each group from pretreatment to posttreatment were assessed, and Pearson correlation analysis …was used to analyze the correlations among skeletal changes. RESULTS: The three-dimensional changes in condylar position were insignificant after surgical-orthodontic treatment in either group (P  > 0.05). However, in the one-jaw surgery group, there were significant backward rotations of the condyle and ramus on the nondeviated side (P  < 0.05), and the condyle on the deviated side rotated inward and forward significantly in the two-jaw surgery group (P  < 0.05) at T2. There were no significant differences in the changes in the total alveolar bone thickness of bilateral first molars during dental decompensation (P  > 0.05). The ratio between the buccal and the total bone thickness around the maxillary first molar on the deviated side decreased significantly at T1, as did those around the mandibular first molar on the nondeviated side (P  < 0.05). CONCLUSIONS: Condylar angulations were less stable after treatment (7 to 9 months after surgery) in both the one-jaw and the two-jaw surgery groups, while condylar displacements were insignificant. In addition, orthodontists should keep a watchful eye to the relative position of the root in the alveolar bone during tooth decompensation. Show more

Keywords: Skeletal class III patients with facial asymmetry, cone-beam computerized tomography (CBCT), surgical-orthodontic treatment

DOI: 10.3233/XST-190628

Citation: Journal of X-Ray Science and Technology, vol. 28, no. 4, pp. 783-798, 2020

Authors: Shao, Shuo | Mao, Ning | Liu, Wenjuan | Cui, Jingjing | Xue, Xiaoli | Cheng, Jingfeng | Zheng, Ning | Wang, Bin

Article Type: Research Article

Abstract: OBJECTIVE: To evaluate the utility of radiomics analysis for differentiating benign and malignant epithelial salivary gland tumors on diffusion-weighted imaging (DWI). METHODS: A retrospective dataset involving 218 and 51 patients with histology-confirmed benign and malignant epithelial salivary gland tumors was used in this study. A total of 396 radiomic features were extracted from the DW images. Analysis of variance (ANOVA) and least-absolute shrinkage and selection operator regression (LASSO) were used to select optimal radiomic features. The selected features were used to build three classification models namely, logistic regression method (LR), support vector machine (SVM), and K-nearest neighbor (KNN) …by using a five-fold cross validation strategy on the training dataset. The diagnostic performance of each classification model was quantified by receiver operating characteristic (ROC) curve and area under the ROC curve (AUC) in the training and validation datasets. RESULTS: Eight most valuable features were selected by LASSO. LR and SVM models yielded optimally diagnostic performance. In the training dataset, LR and SVM yielded AUC values of 0.886 and 0.893 via five-fold cross validation, respectively, while KNN model showed relatively lower AUC (0.796). In the testing dataset, a similar result was found, where AUC values for LR, SVM, and KNN were 0.876, 0.870, and 0.791, respectively. CONCLUSIONS: Classification models based on optimally selected radiomics features computed from DW images present a promising predictive value in distinguishing benign and malignant epithelial salivary gland tumors and thus have potential to be used for preoperative auxiliary diagnosis. Show more

Keywords: Benign salivary gland tumor, malignant salivary gland tumor, diffusion-weighted imaging, radiomics, machine-learning model

DOI: 10.3233/XST-190632

Citation: Journal of X-Ray Science and Technology, vol. 28, no. 4, pp. 799-808, 2020

Authors: Wang, Xisheng | Zhang, Zejian | Fang, Lie kui | Chen, Dong | Peng, Naixiong | Thakker, Parth Udayan | Schwartz, Marshall Zane | Zhang, Yuanyuan

Article Type: Research Article

Abstract: INTRODUCTION: Testicular infarction is a rare complication of prolonged epididymitis and may be misdiagnosed as testicular torsion. In this study, we present three cases of testicular infarction and discuss their clinical characteristics, imaging features and clinical management. PATIENTS AND METHODS: Three adult males with prolonged epididymitis presented with chronic unilateral testicular pain, tenderness, and palpable swelling, including left varicocele in one case and hydrocele in the other two cases. Patient’s symptoms were not relieved after antibiotic therapy. We analyzed the diagnosis, management, and outcome of these three cases of testicular infarction resulting from prolonged epididymitis. This includes the …clinical characteristics, features of color doppler ultrasound imaging for diagnosis, and treatment strategy for testicular infarction from prolonged epididymitis. RESULTS: Complete blood count (CBC) indicated a small leukocytosis (10.6±0.4×109 /L; normal arrange 3.5–9.5 WBC×109 /L). Color doppler images demonstrated appropriate blood flow to areas of interest at patient’s initial visit. At follow up visit several months later, the increased blood flow was detected at the edges of the involved testes with no blood flow to the center. The sizes of the involved testis (27±4 ml) was significantly larger compared to the non affected side (17±2 ml) (p  < 0.05 ). Unilateral simple orchiectomy was performed on the involved testis in all three cases. Grossly, abscess cavities with caseous necrosis were found at the center of the testicle and epididymis in two patients. Histopathologic examination showed chronic inflammation with lymphocytic and macrophage infiltration of the involved testicle in two cases. The third case stained positive for acid fast bacteria. Left varicocele disappeared postoperatively in one patient. No pain, wound infection or other discomfort were noted 12 months after surgery. COMMENTS: This series revealed that testicular infarction may result from inappropriately treated prolonged epididymitis. Epididymal tuberculosis should be considered in cases with epididymitis not responding to broad spectrum antibiotics. Testicular infarction induced by prolonged epididymitis is easily missed due to a lack of symptom changes. Color doppler images are helpful in the diagnosis. This usually presents as a decrease in blood flow at the center of the testis with the increased flow at the periphery differentiating this from testicular torsion. Show more

Keywords: Epididymitis, infarction, testicular, orchiectomy, tuberculosis

DOI: 10.3233/XST-200671

Citation: Journal of X-Ray Science and Technology, vol. 28, no. 4, pp. 809-819, 2020