Bulletin of the American Physical Society
APS March Meeting 2020
Volume 65, Number 1
Monday–Friday, March 2–6, 2020; Denver, Colorado
Session A06: Physics of Medical DevicesFocus
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Sponsoring Units: GMED FIAP Chair: Stephen Russek, National Institute of Standards and Technology Boulder Room: 113 |
Monday, March 2, 2020 8:00AM - 8:36AM |
A06.00001: The Physics of System Integration: Merging Radiotherapy and Magnetic Resonance Imaging to Improve Patient Outcomes Invited Speaker: Michael Thompson The integration of imaging into radiotherapy presents an opportunity to improve the precision and accuracy of radiation delivery to the therapy target. More precise delivery is expected, and has been shown in some cases, to reduce treatment times, radiation toxicity, and improve outcomes. However, to achieve these goals two systems that rely on very accurate electromagnetic fields must be integrated without compromising the performance of either system. In this talk the advantages of integrating low field MRI with radiotherapy will be briefly reviewed. The challenges involved with integrating an MRI system and a linear accelerator to effect superior image guided, and intensity modulated, radiotherapy will be covered in some detail with specific examples. |
Monday, March 2, 2020 8:36AM - 9:12AM |
A06.00002: Proteomic Assay to Predict Health, Wellness, and Disease Invited Speaker: Jason Cleveland The ever-changing state of the proteins in your body is arguably one of the most important indicators of health and disease, but, to date, measurements have only been possible on individual proteins or small multiplexes. SomaLogic has commercialized a rapid proteomic scanning platform (SOMAScan) that quantifies over 5000 proteins in blood or urine spanning 7 orders of magnitude in concentration, with sub-pM limits of detection. The assay relies on SOMAmers (Slow-Offrate-Modified AptaMERs), short pieces of DNA with additional chemical diversity that are selected to bind tightly to a specific protein. Rather than directly measure the proteins themselves, the fundamental principle underlying the assay is to turn a protein counting problem into a DNA counting problem. DNA has a few important differences relative to proteins that make the DNA counting problem much more tractable, including that a chemical complement exists, and that DNA can be amplified and sequenced inexpensively. To date, we have measured over 100,000 human samples. Applying machine learning to the large resulting databases has led to a rapidly growing number of heath measures, including diabetes and cardiovascular risk, with the ultimate goal of providing hundreds of results from a single liquid sample. I will briefly review the physics underlying the current assay and highlight a few of the health measurements. I will also briefly address some thoughts on future device physics to move the assay from the lab to the home. |
Monday, March 2, 2020 9:12AM - 9:24AM |
A06.00003: Light-induced pathogenic bacterial deactivation by using graphene quantum dot and methylene blue Ermek Belekov, Lauren Cooper, Khomidkhodza Kholikov, Ali O Er Graphene quantum dots (GQD) is one of the most promising antimicrobial agents with promising potential in photodynamic therapy. GQD was obtained from benzene by focusing high power nanosecond laser pulses. Detailed characterization was performed with transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier-transform infrared (FTIR), UV-Visible (UV-Vis), and photoluminescence (PL) spectra. Later, we have attached Methylene Blue (MB), a standard photosensitizer, to graphene quantum dots. The effectiveness of the MB/GQD compound was evaluated on different strains of bacteria such as Escherichia coli and Micrococcus luteus. In addition, MTT assay was used to study human cellular side-effects, cancer and noncancer cellular viability under dark conditions. Combining MB with GQDs caused enhanced singlet oxygen generation and a higher deactivation rate compared to MB and GQD only. These results suggest that the MB/GQD combination is a promising form of photodynamic therapy. Further, ongoing experiments on the germicidal effects of different nanoparticles such as silver (Ag), and aluminum (Al) with MB will be presented. |
Monday, March 2, 2020 9:24AM - 9:36AM |
A06.00004: Analysis of experimental acoustic waves induced by high energy pulsed X-ray beams Farnoush Forghani, Adam Mahl, Bernard Jones, Mark Borden, Moyed Miften, David Thomas X-ray induced acoustic tomography has recently gained attention for its potential use for 3D dose distribution imaging in radiation therapy and for low dose high resolution 3D imaging in diagnostic therapy. X-ray acoustic waves are produced by the temperature rise following the energy absorption from a pulsed photon beam. While the theory for X-ray acoustics is well established, there is little known about how the X-ray source properties affect the acoustic signal strength and frequency. Here, we present current experimental results of the X-ray acoustic signals obtained by two types of X-ray sources; megavoltage energy with a long pulse width (4 us) and kilovoltage energy with short pulse width (10 ns). The effect of the pulse length and the X-ray source energy on the acoustic signals are investigated. Experimental acoustic signals with high signal to noise ratio are generated when the X-rays strike thin sheets (between 0.1-3 mm) of a high Z material in a water tank. The experimental signals are compared to simulated acoustic waves using Monte Carlo modeling combined with a numerical solver for time domain acoustic wave propagation (kWave). |
Monday, March 2, 2020 9:36AM - 9:48AM |
A06.00005: Optimizing coded aperture imaging techniques to allow for online tracking of fiducial markers using high energy scattered radiation from clinical treatment beam. Adam Mahl, Brian Miller, Moyed Miften, Bernard Jones Real time visualization of fiducial markers and their movement as surrogates for tumor motion during radiotherapy treatment allows for more accurate dose delivery. This project aims to optimize techniques for online tracking by detecting the scattered radiation from clinical treatment beams through a coded aperture (CA). |
Monday, March 2, 2020 9:48AM - 10:00AM |
A06.00006: Imaging Surgical Devices with Reduced Metal Artifact Pengwei Wu, Niral Sheth, Alejandro Sisniega, Ali Uneri, Runze Han, Rohan Vijayan, Prasad Vagdargi, Bjoern Kreher, Holger Kunze, Gerhard Kleinszig, Sebastian Vogt, Jeffrey H Siewerdsen Imaging in OR is essential to high-precision, minimally invasive spine surgery, but artifacts arising from surgical devices (e.g., implanted screws) present a major challenge to image quality. Such metal objects cause spectral shift (beam-hardening), photon starvation, and scatter, which confound visualization in regions near surgical devices – e.g. to assess the accuracy of screw placement. We present a method to predict patient and device specific orbits of C-arm cone-beam CT system that avoid metal artifacts by acquiring projection data with minimal influence from metal-related polyenergetic bias (spectral shift). The method localizes devices via neural network segmentation in a few low-dose scout views (commonly acquired for patient positioning), and all C-arm rotation and tilt angles are analyzed to identify the orbit with minimal polyenergetic bias. The method was evaluated in simulation, phantoms, and a cadaver with multiple pedicle screws, demonstrating accurate prediction of orbits that optimally avoided metal artifacts. The results yielded ~200-500 HU reduction of shading artifacts, and ~30-45% reduction in blooming artifacts about the screw shaft. Such method can improve the safety and precision of spine surgery. |
Monday, March 2, 2020 10:00AM - 10:12AM |
A06.00007: Personalized radiation attenuating materials for mucosal protection James Donald Byrne, Jennifer Pursley, Kyla Remillard, Samantha Edgington, Jonathan D Schoenfeld, Giovanni Traverso Patients receiving radiation therapy will develop normal tissue injury as a result of treatment. If a radiation attenuating material is placed in normal tissues, it may reduce the radiation received by that tissue. In this study, we measured the radiation attenuating properties of different materials. We investigated the dosimetric impact of three patient-specific radioprotective devices: a 3D-printed intra-oral device for oral cavity cancer patients, and balloon catheters with radioprotective liquids in the esophagus and rectum for lung and prostate cancer patients respectively. The oral cavity and rectum devices demonstrated protective properties in retrospective treatment plans, so in vivo application of these devices was tested in a rat model. Rats treated with the protective devices in place showed decreased ulcerations and erythema of the oral and rectal mucosa compared to control animals. Use of radioprotective devices in patients has the potential to reduce the morbidity of radiation treatments for cancer. |
Monday, March 2, 2020 10:12AM - 10:24AM |
A06.00008: Fast, Small Volume Blood Diagnostics using Homogeneous Thin Solid Films of µL-sized Drops on Super-Hydrophilic Coatings - Impact of Film Properties on Test Accuracy Nikhil Suresh, Shaurya Khanna, Amber A. Chow, Aashi R Gurijala, Mohammed Sahal, Sukesh Ram, Saaketh R Narayan, Nicole Herbots, Thilina Balasooriya, Wesley Peng, Eric J. Culbertson, Robert J Culbertson Blood diagnostic tests require ~7 mL of blood, taking hours for results. Repeated testing can cause Hospital-Acquired Anemia. Accurate blood testing methods with smaller blood volumes and shorter analysis time are needed. |
Monday, March 2, 2020 10:24AM - 10:36AM |
A06.00009: Selection of High Quality Sperm with Lower DNA Fragmentation Afrouz Ataei, Andy W.C. Lau, Theodora Leventouri, Waseem Asghar The first step of in-vitro fertilization is to sort out the motile sperm from the non-motile. Centrifugation based sperm swim-up and density gradient separation are common methods to sort sperm. However, these methods reduce sperm quality during the repetitive centrifugation steps and isolate sperm with high DNA fragmentation. In this work, we construct a microfluidic device based on the observation that motile sperm can swim against the flow within a specific range of flow rates. This sperm-sorting device consists of two chambers, top and bottom separated by a filter. After 45 minutes the sorted motile sperm is collected from the top retrieval chamber and placed on a glass slide for visual inspection with a light microscopy and data collection. The process is repeated for various flow rates. We find that 1) the most motile and functional sperm pass selectively through the micropores against the flow; 2) the optimum flow rate is the one that gives the highest concentration of motile sperm, the lowest DNA fragmentation and higher percentage of morphologically normal sperm. Our device provides an efficient, inexpensive way to sort sperm-out without the disadvantages of centrifugation. |
Monday, March 2, 2020 10:36AM - 10:48AM |
A06.00010: Characterization of neuroblastoma SH-SY5Y cell lines using dielectrophoresis Samaneh Rikhtehgaran, Luc T Wille, Theodora Leventouri, Jianning Wei, E Du Dielectrophoresis (DEP) is a frequency-selective translation of polarized particles under the spatially nonuniform electric field. Particles can move toward the high-field region by positive DEP (pDEP) or away from high-field region by negative DEP (nDEP). This method is label-free, fast and noninvasive characterizing the electrical properties of neuroblastoma SH-SY5Y cell lines. This cell line has been used as an in vitro cell model for the study of Parkinson’s disease or neuronal function and differentiation. We constructed a microdevice that consists of two parts: the interdigitated ITO electrodes to generate AC electric field and a Polydimethylsiloxane (PDMS) with two wells to inject the cells and the media. Then the measured DEP frequency spectra fitted using the spherical shell model to compute electrical properties of the cells. |
Monday, March 2, 2020 10:48AM - 11:00AM |
A06.00011: Optimize The Blood Flow In Blood Vessels By Magnet Field To Cure Hypertension Rongjia Tao Sever hypertension comes with headaches, chest pain, shortness of breath, flushing, and visual changes etc. Without timely medical treatment, sever hypertension will lead to heart attack and strokes. Here we report our discovery: the blood flow in blood vessels can be optimized by application of a strong magnetic field along its flow direction. The red blood cells are polarized and aggregated into short chains. The blood viscosity along the flow direction is significantly reduced, turbulence is suppressed, and the flow becomes stable laminar. Hence the blood pressure is lowered down to the normal range. Our clinical trials have more than 250 people tested. The technology is effective for everyone. On average, in 15 minutes the magnetic treatment lowers the blood pressure by 21.4%. The effect lasts more than 24 hours and can be kept continuously if the magnetic treatment is repearted everyday. Our placebo tests have also confirmed that without application of magnetic field, the blood pressure cannot be lowered. The effect is truly produced by improvement of blood flow with magnetic field. We expect that this technology will help people to cure hypertension, preventing cardiovascular diseases. |
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