A feasibility study on the development and use of a deep learning model to automate real-time monitoring of tumor position and assessment of interfraction fiducial marker migration in prostate radiotherapy patients

Purpose The aim of this study was to assess the feasibility of the development and training of a deep learning object detection model for automating the assessment of fiducial marker migration and tracking of the prostate in radiotherapy patients. Methods and Materials A fiducial marker detection model was trained on the YOLO v2 detection framework using approximately 20,000 pelvis kV projection images with fiducial markers labelled. The ability of the trained model to detect marker positions was validated by tracking the motion of markers in a respiratory phantom and comparing detection data with the expected displacement from a reference position. Marker migration was then assessed in 14 prostate radiotherapy patients using the detector for comparison with previously conducted studies. This was done by determining variations in intermarker distance between the first and subsequent fractions in each patient. Results On completion of training, a detection model was developed that operated at a 96% detection efficacy and with a root mean square error of 0.3 pixels. By determining the displacement from a reference position in a respiratory phantom, experimentally and with the detector it was found that the detector was able to compute displacements with a mean accuracy of 97.8% when compared to the actual values. Interfraction marker migration was measured in 14 patients and the average and maximum ± standard deviation marker migration were found to be 2.0±0.9 mm and 2.3±0.9 mm, respectively. Conclusion This study demonstrates the benefits of pairing deep learning object detection, and image-guided radiotherapy and how a workflow to automate the assessment of organ motion and seed migration during prostate radiotherapy can be developed. The high detection efficacy and low error make the advantages of using a pre-trained model to automate the assessment of the target volume positional variation and the migration of fiducial markers between fractions.

A Novel Application of Wiegand Effect for Generating a Reference Signal in Linear Positioning System

With the development of industry, the application of linear positioning system has become more and more extensive, ranging from machine tools to optical inspection, laser processing, and robots. With the increase in applications of linear positioning system, linear positioning system has higher and higher requirements for accuracy and environment. Because of errors in assembly and processing of the linear motor stage, degradation of precision accuracy is commonly observed. The common used method for improving the accuracy is with laser interferometer to measure positioning errors, from which errors the corresponding error map can be built. The error map is then stored in motion controller to real-time compensate the positioning error. Since this method requires a reference position as the starting point of for error compensation with the pre-built error map, the reference position inevitably requires high repeatability so that the error map can effectively compensate the positioning error. Although reference signal generated by optical sensors has high repeatability and narrow pulse width, but it cannot maintain performance under severe ambient conditions caused by oil, water or dust. Hall-effect sensor can be used under severe ambient conditions; however, its signal has low repeatability and wide pulse width. It is then inappropriate for high precision requirements. This research presented in this paper is on the novel application of Wiegand effect for generating a reference signal. Wiegand effect can generate sharp pulse and the triggering of the pulse is independent of drive frequency. In this research, we use experiments and simulations to examine the relationship between different designs of magnetic circuit and repeatability of Wiegand pulse, which are later used to optimize the magnetic design of the system to improve the repeatability of Wiegand pulse.

Physiologic Long Head Biceps Tendon Excursion Throughout Shoulder Range of Motion: A Cadaveric Study

Background: Restoration of the long head of the biceps tendon (LHBT) length-tension relationship is critical in preserving muscle strength and efficiency when performing biceps tenodesis. While static anatomic landmarks such as the inferior border of the pectoralis major may be used intraoperatively to achieve this, shoulder position may affect the excursion of the biceps tendon and represents another variable to consider. Purpose/Hypothesis: The purpose of this study was to quantitatively evaluate the normal excursion of LHBT that occurs through a glenohumeral range of motion. We also sought to determine whether elbow position affects LHBT excursion. We hypothesized that LHBT excursion will be affected by glenohumeral flexion and extension, and elbow extension will result in increased excursion at each glenohumeral position compared with a neutral position. Study Design: Controlled laboratory study. Methods: A total of 10 fresh-frozen specimens underwent a standard approach for subpectoral biceps tenodesis. The LHBT was identified and tagged with a radiopaque marker within zone 3 of the bicipital tunnel. A total of 3 K-wires were then drilled into the osseous floor: one at the level of the marker in the LHBT, one at 1 cm proximal, and a third 1 cm distal. All 3 K-wires were then cut flush with the anterior humeral cortex. The specimens were next placed into 8 different positions, and the excursion of the LHBT was measured by referencing the K-wires using static fluoroscopic imaging. The results were analyzed using 1-way analysis of variance testing followed by Tukey honestly significant difference testing for pairwise comparison between each individual position and the reference position. Results: The average total LHBT excursion was 24.4 ± 5.2 mm between the neutral shoulder position and the other shoulder positions tested. The position of the LHBT was significantly different in the reference position compared with each of the other 7 shoulder positions ( P < .001). Additionally, the 2 positions of shoulder extension had different LHBT excursions when compared with each position of shoulder flexion ( P < .0001). For each shoulder position tested, the position of the LHBT was not significantly different in elbow flexion compared with extension. Conclusion: There is approximately 24 mm of LHBT excursion throughout the glenohumeral range of motion, with significantly different amounts of excursion in glenohumeral flexion and extension. Elbow position does not significantly affect LHBT excursion. Positioning the shoulder in extension during biceps tenodesis may overtension the biceps, while positioning the shoulder in flexion may undertension the biceps relative to the neutral position. Further research is needed to identify the optimal shoulder position for biceps tenodesis. Clinical Relevance: Shoulder positioning is an important consideration in establishing a normal length-tension relationship during biceps tenodesis. When compared with flexed shoulder positions, LHBT excursion significantly differs in positions of extension and in a neutral position.

Bend-Direction and Rotation Plastic Optical Fiber Sensor

A plastic filament of poly (methyl methacrylate) (PMMA) was fabricated by extrusion. The mode confinement was simulated using numerical software. The idea is to study how the light intensity changes inside the plastic optical fiber (POF) when a bending in multiple directions is applied. The results obtained from the simulation were compared to the experimental observations. The non-circular shape of the POF allows sensing a rotation applied as well. The angle of rotation was obtained processing two images of the end facet of the fiber (one with the fiber in a reference position and one with the rotated fiber), using an intensity-based automatic image registration. The accuracy in the rotation calculation was of 0.01°.

Positional repeatability and variation in internal and external markers during volumetric-modulated arc therapy under end-exhalation breath-hold conditions for pancreatic cancer patients

The purpose of this study was to assess the positional repeatability of internal and external markers among multiple breath-hold (BH) sessions and evaluate the positional variation of these markers within BH sessions for volumetric-modulated arc therapy (VMAT) for pancreatic cancer patients. A total of 13 consecutive pancreatic cancer patients with an internal marker were enrolled. Single full-arc coplanar VMAT was delivered under end-exhalation BH conditions while monitoring the internal marker with kilovoltage (kV) X-ray fluoroscopy. Positional repeatability of the internal and external markers was determined by the difference between the reference and zero position in all BH sessions, and positional variation was defined by the displacement from the reference position in each BH session during megavolt beam delivery. The overall positional repeatability was 0.6 ± 1.5 mm in the X-axis for the centroid of the internal marker (CoIM), −0.1 ± 2.2 mm in the Y-axis for the CoIM, and 0.8 ± 2.2 mm for the external marker. The frequency of an internal marker position appearing &gt; 2 mm from the reference position in the Y-axis, despite the external marker position being ≤2 mm from the reference position, ranged from 0.0 to 39.9% for each patient. Meanwhile, the proportion of sessions with positional variation ≤2 mm was 93.2 and 98.7% for the CoIM and external marker, respectively. External marker motion can be used as a surrogate for pancreatic tumor motion during BH-VMAT delivery; however, margins of ~5 mm were required to ensure positional repeatability.

Positional repeatability and variation in internal and external markers during volumetric-modulated arc therapy under end-exhalation breath-hold conditions for pancreatic cancer patients

Background: To assess the positional repeatability of internal and external markers among multiple breath-hold (BH) sessions and assess the positional variation of these markers within BH sessions for volumetric-modulated arc therapy (VMAT) for pancreatic cancer patients. Methods: A total of 13 consecutive pancreatic cancer patients with an internal marker were enrolled. Single full-arc coplanar VMAT was delivered under end-exhalation (EE) BH conditions, while monitoring the internal marker with kilovoltage (kV) X-ray fluoroscopy. Positional repeatability of internal and external markers was indicated by the difference between the reference marker position and the marker position at the beginning of each BH session, and positional variation was indicated by the maximum displacement of the marker during each BH session. Results: The overall positional repeatability was 0.6 ± 1.5 mm in the X-axis for the centroid of the internal marker (CoIM), -0.1 ± 2.2 mm in the Y-axis for the CoIM, and 0.8 ± 2.2 mm for the external marker. An internal marker position > 2 mm from the reference position in the Y-axis was observed in 19.1% of all BH sessions, despite the external marker position being ≤ 2 mm from the reference position. Meanwhile, the proportion of sessions with positional variation ≤ 2 mm was 93.2% and 98.7% for the CoIM and external marker, respectively. Conclusions: External marker motion can be used as a surrogate for pancreatic tumor motion during BH-VMAT; however, an optimal internal margin is required to ensure positional repeatability.

Fourier-based contour descriptors to relax positional standardization of the otolith images in AFORO queries

The otolith digital catalogue AFORO allows unknown otoliths to be classified automatically by using a comparison with its classified records. To do this, the otolith’s contour, which is extracted from an image, is used. In AFORO, otolith images follow a strict positional normalization. Only the left sagitta is considered, and the images must show the internal side of the whole otolith, with the sulcus acusticus visible, the dorsal side (D) placed in the dorsal position and the rostral side (R) placed on the right. The otolith in the incoming image to be classified must also follow the same positional normalization. Variations from the reference position worsen the classification results. In this article, robust contour descriptors are proposed to extend this functionality of AFORO to the images of otoliths that are poorly normalized, contain rotations, are entirely inverted or came from the right rather than the left sagitta. These descriptors are based on the discrete Fourier transform and could extend the classification functionality to incoming images that are taken and sent, for instance, from smartphones in a wide range of working conditions.

Mecanismo Diseñado y Simulado Virtualmente

Objectives: To show a process to synthesize and analyze a crank mechanism oscillator function generator. Simulate it in a virtual reality environment, without losing its physical characteristic. Evaluate deviations between analytically desired and virtually obtained. Methodology: Using the analytical method described by Hartenberg and Denavit, a graphic package and an electronic spreadsheet; knowing the angle of rotation of the crank, the angular reference position of the crank, the displacement of the oscillator, the extreme values of the independent variable and the function; precision positions, link lengths, eccentricity and oscillator reference position were determined. The links were generated, the mechanism was assembled, analyzing fifteen of its positions. Of the infinite number of existing solutions, five were synthesized. For each solution that justify it, the deviation of the generated function was evaluated with respect to the desired one. Contribution: The friendly, fast, safe, accurate and parametric process was demonstrated; modifying the inputs and checking the update of the outputs, therefore it is a contribution to the scientific progress of the area.

Investigating the Link between Unemployment and Disability

Informed by an overview of job advertisement research published during the past two decades, the purpose of this study is to address disability and employment in library and information science by investigating job ads for academic library reference positions for their written language comprehension qualities. With concerns for rising unemployment rates of qualified, college educated individuals with disabilities including Autism Spectrum Disorders (ASD) and the need to increase diversity in the workforce, we conducted a multi-step content analysis of all academic library reference position advertisements (43) published by libraries in the 12 member states of a Midwestern United States regional library association. The theoretical lens for our study draws on the field of linguistics and particularly two important components of discourse, the reading of 1) words and sentences containing lexically ambiguous words and 2) fixed formulaic sequences. From the identified reference position job ads (148 pages, 16,724 words), 79 passages were coded as problematic in the announcement areas of 1) general position information (23), 2) duty and/or responsibility (34), and 3) qualifications (22). Passages were organized into 32 categorical examples of lexically ambiguous words and 15 examples of formulaic sequences that do not in our view have universal meaning and can lead to uncertainty and misunderstandings among potential applicants with and without intellectual disabilities. Examples of clear, accurate language to replace problematic language are presented. While this study focuses on job ads in the United States, it has international implications and relevance as ASD and related disabilities exist worldwide.