Effectiveness of a low-intensity static magnetic field in accelerating upper canine retraction: a randomized controlled clinical trial.

INTRODUCTION: Neodymium-iron-boron magnets have been suggested as a contemporary method for accelerating the process of orthodontic tooth movement (OTM). A limited number of clinical trials evaluated their effectiveness in accelerating OTM which is desirable for both orthodontists and patients. The present study aimed to investigate the effectiveness of a low-intensity static magnetic field (SMF) in accelerating upper canine retraction movement. MATERIALS AND METHODS: Seventeen patients (mean age 20.76 ± 2.9 years) with their orthodontic treatment decision to extract the upper and lower first premolars due to bimaxillary protrusion malocclusion were included in this split-mouth study. Canine retraction was performed using Nickel-titanium (Ni-Ti) closed-coil springs (150 g of force on each side). The experimental side received SMF via an auxiliary wire that carried 4-neodymium iron-born magnets with an air gap of 2 mm between the magnets to produce a magnetic field density of 414 mT in the region corresponding to the lateral ligament of the upper canine. To determine the rate of upper canine retraction and upper molar drift, alginate impressions were taken once a month to create plaster casts, which were analyzed digitally via a three-dimensional method. RESULTS: The rate of upper canine retraction was significantly greater (P < 0.05) on the SMF side than that on the control side during the first and second months, with an overall duration (19.16%) that was greater than that on the control side. The peak acceleration occurred during the second month (38.09%). No significant differences in upper molar drift were detected between the experimental and control sides (P > 0.05). CONCLUSION: A low-intensity static magnetic field was effective at accelerating upper canine retraction. The difference between the two sides was statistically significant but may not be clinically significant. The SMF did not affect upper molar drift during the upper canine retraction phase. TRIAL REGISTRATION: The trial was retrospectively registered at the ISRCTN registry ( ISRCTN59092624 ) (31/05/2022).

Optimized Cylindrical Diffuser Powers for Interstitial PDT Breast Cancer Treatment Planning: A Simulation Study.

PURPOSE: It is well known that interstitial photodynamic therapy (iPDT) of large tumors requires effective planning to ensure efficient delivery of therapeutic dose to the target tumors. This should be achieved in parallel with minimal damage to the nearby intact tissues. To that end, clinical iPDT can be attained using cylindrical diffusing optical fibers (CDFs) as light sources. In this work, we optimize output CDF powers in order to deliver a prescribed light dose to a spherical volume such as a tumor node. METHODS: Four CDFs are placed vertically inside the tumor node. The fluence rate is calculated using the diffusion equation. Therapeutic target dose is (20-50) J·cm-2. The optical properties (µ a = 0.085 cm-1, µ s' = 16 cm-1) of a breast tumor and the treatment time of 150 sec are used to calculate the fluence rate. RESULTS: For four CDFs, the therapeutic target dose (20-50) J·cm-2 is delivered to more than 90%. This is the ratio of the total points that receive the target dose in proportion to the total points in the volume of the node of 3 cm in diameter, whereas, in larger nodes, the ratio is decreased to approximately 67%. Five CDFs are required to improve this ratio by more than 10%. CONCLUSION: Optimizing delivered powers enables the distribution of the therapeutic dose uniformly in the medium. In addition, this simulation study represents an essential part of a development dosimetry system for measuring and controlling the optical dose in the breast tumors.

Statistical approach for brain cancer classification using a region growing threshold.

In brain cancer, a biopsy as an invasive procedure is needed in order to differentiate between malignant and benign brain tumor. However, in some cases, it is difficult or harmful to perform such a procedure, to the brain. The aim of this study is to investigate a new method in maximizing the probability of brain cancer type detection without actual biopsy procedure. The proposed method combines both image and statistical analysis for tumor type detection. It employed image filtration and segmentation of the target region of interest with MRI to assure an accurate statistical interpretation of the results. Statistical analysis was based on utilizing the mean, range, box plot, and testing of hypothesis techniques to reach acceptable and accurate results in differentiating between those two types. This method was performed, examined and compared on actual patients with brain tumors. The results showed that the proposed method was quite successful in distinguishing between malignant and benign brain tumor with 95% confident that the results are correct based on statistical testing of hypothesis.

Utilizing wavelet transform and support vector machine for detection of the paradoxical splitting in the second heart sound.

Paradoxical splitting occurs when pulmonic valve (P2) closes before the aortic valve (A2). This causes second heart sound (S2) to be a single sound during inspiration and split during exhalation. Etiology delay in aortic closure: aortic stenosis, volume overload of left ventricle (LV), conduction defects in LV, and left bundle branch block (LBBB). In this article, a method was proposed in early detection of a reverse in the appearance of A2 and P2 within S2. This method is based on the time-frequency maps obtained with the continuous wavelet transform (CWT), namely, the Meyer wavelet. A number of patients with LBBB and others with fitted pacemakers were studied. The above method is combined with the support vector machine (SVM) and performance of this method is evaluated using classification accuracy (Ca), sensitivity (Se), specificity, positive, and negative predicted values. Results show that it is relatively easy to detect the reverse in A2 and P2 and the Ca and Se is 90.97 and 94.44%, respectively, for the sample of 42 patients whose data were collected from the Cardiology Department at Brighton and Sussex University Hospital in England.