Temperature Changes in Oral All-Ceramic Materials with Different Optical Properties under Er:YAG Laser Irradiation.

Objectives: This in vitro study is aimed at assessing the oral all-ceramic materials energy transmission and temperature changes after Er:YAG laser irradiation of monolithic zirconia all-ceramic materials with varying optical properties. Materials and Methods: Two monolithic zirconia materials, Zenostar T and X-CERA TT (monolithic Zirconia), were studied. Specimens were divided into four groups, with a thickness of 1.0, 1.5, 2.0, and 2.5 mm, respectively. The chemical elemental composition of the two materials was determined using X-ray spectroscopy and Fourier transform infrared spectroscopy. The light transmittance of specimens with different thicknesses was measured using a spectrophotometer at three wavelength ranges: 200-380, 380-780, and 780-2500 nm. Irradiation with Er:YAG laser was performed, and the resultant temperature changes were measured using a thermocouple thermometer. Results: Compositional analysis indicated that Si content in X-CERA TT was higher than that in Zenostar T. The light transmittance of both materials decreased as specimen thickness increased. Er:YAG laser irradiation led to temperature increase at both Zenostar T (26.4°C-81.7°C) and X-CERA TT (23.9°C-53.5°C) specimens. Both optical transmittance and temperature changes after Er:YAG laser irradiation were consistent with exponential distribution against different thickness levels. Conclusion: Er:YAG laser penetration energy and resultant temperature changes were mainly determined by the thickness and composition of the examined monolithic zirconia materials.

[Development of a New-type Nail-fold Microcirculation Imaging Device].

At present, there are many problems in the nail-fold microcirculation detection devices, such as huge structure, inconvenience to carry. In addition, due to the patient's body shaking, the video is difficult to keep stable in collecting with the device, which brings great difficulties to the doctor's observation. We develop a small image acquisition device for nail-fold microcirculation based on the principle of SDF imaging principle and liquid lenses technology. An annular lighting device is fixed in front of the optical system, and the overall design of the system is based on the characteristics of human fingers. The device is small, easy to carry and conform to the fingertips. It can focus quickly through a controller. It can also achieve high quality images of the nail-fold microcirculation. This study can promote the usage of nail-fold microcirculation device at the bedside. It's an efficient tool for medical workers to observe the microcirculation of patients.

Automatic reconstruction method for high-contrast panoramic image from dental cone-beam CT data.

BACKGROUND AND OBJECTIVE: Panoramic images reconstructed from dental cone beam CT (CBCT) data have been effectively used in dental clinics for disease diagnosis. Panoramic images generally have low contrast because excessive non-interest tissues participate in the reconstruction, which may affect the diagnosis. In this study, we developed a fully automatic reconstruction method to improve the global and detail contrast of panoramic images. METHODS: The proposed method consists of dental arch thickness detection, image synthesis, and image enhancement. First, the dental arch thickness is detected from an axial maximum intensity projection (MIP) image generated from the axial slices containing the teeth to reduce non-interest tissues in panoramic image reconstruction. Then, a new synthesis algorithm is proposed at image synthesis stage to reduce the effect of non-interest tissues on image contrast. Finally, an image enhancement algorithm is applied to the synthesized image to improve the detail contrast of the final panoramic image. RESULTS: A total of 129 real clinical dental CBCT data sets were used to test the proposed method. The panoramic images generated by three methods were subjectively scored by three experienced dentists who were blinded to the generated method. The evaluation of image contrast included the maxillary, mandible, teeth, and particular region (root canal, crown reconstruction, implants, and metal brackets). The overall image contrast score revealed that the proposed method scored the highest of 11.03 ±â€¯2.46, followed by the ray sum and x-ray methods with corresponding scores of 6.4 ±â€¯1.65 and 5.35 ±â€¯1.56. The results of expert subjective scoring indicated that the image contrast of the panoramic image generated by the proposed method is higher than those of existing methods. CONCLUSIONS: The proposed method provides a quick, effective and robust solution to improve the global and detail contrast of the panoramic image generated from dental CBCT data.

Volumetric Modulated Arc Therapy versus Fixed-Field Intensity-Modulated Radiotherapy in Radical Irradiation for Cervical Cancer without Lymphadenectasis: Dosimetric and Clinical Results.

BACKGROUND: The aim of this study was to compare the dosimetric parameters, clinical complications, and efficacy of volumetric modulated arc therapy (VMAT) and fixed-field intensity-modulated radiotherapy (f-IMRT) in radical radiotherapy for cervical cancer without lymphadenectasis. METHODS: 84 cervical cancer patients undergoing treatment with VMAT and f-IMRT were selected. Dose-volume histograms were used to evaluate the dose distribution in the planning target volume (PTV) and organs at risk. The clinical complications and efficacy were observed. RESULTS: The homogeneity index (HI) and the conformity index (CI) of VMAT plans were both superior to the HI and CI of f-IMRT plans (p = 0.043, 0.025). VMAT plans resulted in a reduction in the V30 of the rectum and V40 of the bladder (p = 0.002). Furthermore, the monitor units (MUs) for VMAT were less than a quarter of those for f-IMRT. The treatment time for VMAT was less than a half of that for f-IMRT. Both clinical complications and efficacy showed no significant differences. CONCLUSION: VMAT plans showed superior dose coverage of the PTV, better protection of the rectum and bladder in dosimetry, and significantly reduced MUs and treatment time compared with f-IMRT. Clinical results were similar for both plans.

Dosimetric comparison of helical tomotherapy, VMAT, fixed-field IMRT and 3D-conformal radiotherapy for stage I-II nasal natural killer T-cell lymphoma.

BACKGROUND: The aim of this study was to compare radiotherapy plans for Stage I-II nasal natural killer/T-cell lymphoma (NNKTL) using helical tomotherapy (HT), volumetric-modulated arc therapy (VMAT), Fixed-Field intensity-modulated radiotherapy (IMRT), and three-dimensional conformal radiotherapy (3D-CRT). METHODS: Eight patents with Stage I-II NNKTL treated with IMRT were re-planned for HT, VMAT (two full arcs), and 3D-CRT. The quality of target coverage, the exposure of normal tissue and the efficiency of radiation delivery were analyzed. RESULTS: HT showed significant improvement over IMRT in terms of D98%, cold spot volume and homogeneity index (HI) of planning target volume (PTV). VMAT provided best dose uniformity (p = 0.000) to PTV, while HT had best dose homogeneity among the four radiotherapy techniques (p = 0.000) to PTV. VMAT obviously reduced treatment time (p = 0.010; 0.000) compared to HT and IMRT. Mean dose of left and right optic nerve was significantly reduced by IMRT compared to HT (19.86%, p = 0.000; 21.40%, p = 0.002) and VMAT (8.97%, p = 0.002; 9.35%, p = 0.001), and maximum dose of left lens of VMAT increased over the HT (36.25%, p = 0.043) and IMRT (40.65%, p = 0.001). CONCLUSION: The unexpected results show that both HT and VMAT can achieve higher conformal treatment plans while getting worse organs at risk (OARs) sparing than IMRT for patients with Stage I-II NNKTL. VMAT requires the shortest delivery time, and IMRT delivers the lowest dose to most OARs. The results could provide guidance for selecting proper radiation technologies for different cases.