Adaptive High Precision Research Articles

Development and Commercial Application of Glue-Free Adaptive High Precision X-Ray Mirror

Development and Commercial Application of Glue-Free Adaptive High Precision X-Ray Mirror

Acute Toxicity Patterns in Adaptive High Precision Radiotherapy for Head and Neck Cancer - a Randomised Controlled Trial

Adaptive Radiation therapy (ART) aims to take into account the changes in target volume and organs at risk during the course of fractionated radiation therapy & this has possible advantage in terms of improved local control, reduced toxicities and improved the QOL. This study aims to assess the clinical impact of ART in terms of toxicities in primary SCC of HNC undergoing radical/adjuvant concurrent chemo-radiotherapy treatment. The study enrolled 100 patients of histopathologically proven primary head-and-neck cancer and were randomized into ART and non-ART arms. Target/OAR delineation was done after CT simulation following rigid immobilization. All patients were started treatment with VMAT & image guidance. After treatment start, the patients were re-simulated using CT imaging again at 3rd, 5th and 7th week. Predefined adaptive re-contouring workflow using deformable image registration was applied to generate adaptive plan. For patients in ART Arm, the new plan was executed for the remaining fractions. In Non ART Arm treatment was continued as per the original plan. All the patients were observed for total volume of Parotid glands at week 1, 3, 5 and 7. RTOG Criteria was used for documenting acute reactions in form of acute xerostomia, mucositis and dysphagia in both arms at week 3, 5 and 7. Median follow-up was 6mo. The percentage volume change in parotid glands was observed to be 6.25%, 16.37% and 28.39% in adaptive arm and 11.53%, 23.54% and 32.56% at 3, 5 and 7 weeks (P-value 0.009 and 0.0123rd and 5th wk respectively). On clinical examination Grade 2 Xerostomia at 3, 5 and 7 wk was seen in 10%, 36% and 70% patients in adaptive arm whereas in 16%, 46% and 88% in non-adaptive arm (P-value 0.006 at 7th wk). The significant difference in mucosal reactions between both arms was observed throughout the course of study in favour of adaptive arm. None of the patients in adaptive arm had Grade 3 mucosal reactions as compared to 26% in non adaptive arm. The difference in mucosal reaction was most significant at 7th week of treatment (p value 0.004). At week 3 and 5, patients having grade 2 or higher reactions were 14% and 46% in adaptive arm as compared to 26% and 70% in non-adaptive arm. (p values 0.029, 0.023). Dryness of mouth has a significant impact on swallowing. In our study we observed grade 2 or higher dysphagia to be 6%, 38% and 80% in adaptive arm whereas 2%, 48% and 84% in non-adaptive arm at 3, 5 and 7 weeks. Though absolute number of patients having adverse dysphagia reaction was lower in adaptive arm, this difference was not statistically significant (p value 0.15, 0.59, 0.09). Volume changes in parotid glands and gross tumour is observed throughout the course of radiation treatment and ART can aid in better sparing of parotid glands with an advantage over non-ART in terms of reduced acute toxicity reactions. Present study is first RCT reported in literature where an attempt is made to correlate dosimetric and toxicity criteria.

Adaptive high-precision superpixel segmentation

Superpixel as a fundamental processing unit can significantly reduce the computational complexity of subsequent computer vision tasks. In this paper, an Adaptive High-Precision (AHP) superpixel segmentation algorithm is proposed. Three major schemes are proposed in this algorithm. First, a scheme of generating the initial number of superpixels adaptively is proposed by calculating the histogram peak value of L-component corresponding to the smallest salient region. In addition, we show that the isolated pixels are not only existent but also abundant. Instead of using distance-measurement of color and position space, we reclassify each isolated pixel just relying on the LAB color space. Furthermore, the detection and re-segmentation scheme of the under-segmentation superpixels is adopted according to the standard deviation and mean value of the L-component, which can re-segment each under-segmentation superpixel directly without measuring the distance between each under-segmentation pixel and new centroid. The proposed algorithm has linear computational complexity and the merits of adaptivity and high precision. Experiments on the Berkeley segmentation dataset demonstrate the effectiveness and feasibility of the proposed schemes, and they also prove AHP can achieve high-precision superpixel segmentation results in comparison with the state-of-the-art algorithms on standard metrics.

An Adaptive High-Precision Tracking Controller for the Coupled Switched Reluctance Two-Finger Gripper

An adaptive high-precision position control algorithm with online system identification is implemented onto the switched reluctance, two-finger gripper with coupled magnetic paths. Theoretical investigation proves that the magnetic paths from the two fingers are highly coupled. Without the introduction of any decoupling scheme, the position control performance under the proportional integral differential controller and the adaptive controller is inspected and the control results are compared. Experimental results verify that, without introducing any decoupling mechanism, the adaptive controller is capable of independent control of each finger with a high-precision and uniform position control performance.

LQG approach for the high-precision track control of ships

Design ideas and experiences gained during the development of an adaptive high precision track controller for ships are summarised. The controller is installed on a number of different ships, using a variety of position measurement systems. The design follows the spirit of the LQG paradigm combined with a model following feedforward strategy. The ship is kept to a manoeuvring trajectory through a combination of feedforward and LQG feedback control. The variances and weighting coefficients for the LQG controller are chosen systematically. The large number of design parameters is reduced by appropriate model scaling. In addition, a decomposition structure of the Kalman filter is exploited to reveal the important tuning parameters.