A comparative study of methods for surface area and three-dimensional shape measurement of coral skeletons

The three-dimensional morphology and surface area of organisms such as reef-building corals is central to their biology. Consequently, being able to detect and measure this aspect of corals is critical to understanding their interactions with the surrounding environment. This study explores six different methods of three-dimensional shape and surface area measurements using the range of morphology associated with the Scleractinian corals: Goniopora tenuidens, Acropora intermedia, and Porites cylindrica. Wax dipping; foil wrapping; multi-station convergent photogrammetry that used the naturally occurring optical texture for conjugate point matching; stereo photogrammetry that used projected light to provide optical texture; a handheld laser scanner that employed two cameras and a structured light source; and X-ray computer tomography (CT) scanning were applied to each coral skeleton to determine the spatial resolution of surface detection as well as the accuracy of surface area estimate of each method. Compared with X-ray CT wax dipping provided the best estimate of the surface area of coral skeletons that had external corallites, regardless of morphological complexity. Foil wrapping consistently showed a large degree of error on all coral morphologies. The photogrammetry and laser-scanning solutions were effective only on corals with simple morphologies. The two techniques that used projected lighting were both subject to skeletal light scattering, caused by both gross morphology and meso-coral architecture and which degraded signal triangulation, but otherwise provided solutions with good spatial resolution. X-ray CT scanning provided the highest resolution surface area estimates, detecting surface features smaller than 1000 mu m(2)

Next generation of growth-sparing techniques: preliminary clinical results of a magnetically controlled growing rod in 14 patients

Session 3A - Early Onset Scoliosis: Paper no. 33SUMMARY: Growth-sparing techniques are commonly used for the treatment of progressive EOS. The standard growing rod (GR) technique requires multiple surgeries for lengthening. The preliminary results of MCGR has shown the comparable outcomes to standard GR without the need for repeated surgery which can be expected to reduce the overall complication rate in GR surgery. INTRODUCTION: The growing rod (GR) technique for management of progressive Early-Onset Scoliosis (EOS) is a viable alternative but with a high complication rate attributed to frequent surgical lengthenings. The safety and efficacy of a non-invasive Magnetically Controlled Growing Rod (MCGR) has been previously reported in a porcine model. We are reporting the preliminary results of this technique in EOS. METHODS: Retrospective review of prospectively collected multi-center data. Only patients who underwent MCGR surgery and at least 3 subsequent spinal distractions were included in this preliminary review. Distractions were performed in clinic without anesthesia or analgesics. T1-T12 and T1-S1 height and the distraction distance inside the actuator were analyzed in addition to conventional clinical and radiographic data. RESULTS: Patients (N=14; 7 F and 7 M) had a mean age of 8y+10m (3y+6m to 12y+7m) and underwent a total of 14 index surgeries (SR: index single rod in 5 and DR: dual rod in 9) and 91 distractions. There were 5 idiopathic, 4 neuromuscular, 2 congenital, 2 syndromic and one NF. Mean follow-up (FU) was 10 months (5.8-18.2). Mean Cobb changed from 57° pre-op to 35° post-op and correction was maintained (35°) at latest FU. T1-T12 increased by 4 mm for SR and 10 mm for DR with mean monthly gain of 0.5 and 1.39, respectively. T1-S1 gain was 4 mm for SR and 17 mm for DR with mean monthly gain of 0.5 mm for SR and 2.35 mm for DR. The mean interval between index surgery and the first distraction was 66 days and thereafter was 43 days. Complications included one superficial infection in (SR), one prominent implant (DR) and minimal loss of initial distraction in three after index MCGR (all SR). Overall, partial loss of distraction was observed following 14 of the 91 distractions (one DR and 13 SR). This loss was regained in subsequent distractions. There was no neurologic deficit or implant failure. CONCLUSION: MCGR appears to be safe and provided adequate distraction similar to the standard GR technique without the need for repeated surgeries. DR patients had better initial curve correction and greater spinal height. No major complications were observed during the short follow-up period. The FDA has not cleared the drug and/or medical device for the use described in this presentation (i.e., the drug or medical device is being discussed for an ‘off label’ use).postprin

Publications of the Jet Propulsion Laboratory, 1985

This bibliography describes and indexes by primary author the externally distributed technical reporting, released during calender year 1985, that resulted from scientific and engineering work performed, or managed, by the Jet Propulsion Laboratory. Three classes of publications are included: JPL publications in which the information is complete for a specific accomplisment; Articles from the quarterly Telecommunications and Data Acquisition (TDA) Progress Report; and article published in the open literature

Methods of assessing structural integrity for space shuttle vehicles

A detailed description and evaluation of nondestructive evaluation (NDE) methods are given which have application to space shuttle vehicles. Appropriate NDE design data is presented in twelve specifications in an appendix. Recommendations for NDE development work for the space shuttle program are presented

NASA SBIR abstracts of 1991 phase 1 projects

The objectives of 301 projects placed under contract by the Small Business Innovation Research (SBIR) program of the National Aeronautics and Space Administration (NASA) are described. These projects were selected competitively from among proposals submitted to NASA in response to the 1991 SBIR Program Solicitation. The basic document consists of edited, non-proprietary abstracts of the winning proposals submitted by small businesses. The abstracts are presented under the 15 technical topics within which Phase 1 proposals were solicited. Each project was assigned a sequential identifying number from 001 to 301, in order of its appearance in the body of the report. Appendixes to provide additional information about the SBIR program and permit cross-reference of the 1991 Phase 1 projects by company name, location by state, principal investigator, NASA Field Center responsible for management of each project, and NASA contract number are included

Investigation of image quality and radiation exposure to the patients of the low dose 2D/3D slot scan x-ray imaging system compared to conventional digital radiography x-ray imaging systems

Introduktion: Røntgen billeddannelse anvender ioniserende stråling, som kan påvirke biologiske celler og dermed potentielt medføre en risiko for celle skader. Derfor er der en potentiel risiko for genetiske skader og for stråleinduceret cancer, som er eksponentielt stigende med stigende røntgenstråledosis. Selvom risikoen ved diagnostiske røntgenundersøgelser ikke er stor, vil der altid være en teoretisk risiko og derfor skal stråledosis til patienter holdes laveste muligt, for at opfylde ”Aslow As Reasonible Achievebe (ALARA)” princippet. Røntgenudstyrs producenterne forsøger hele tiden at forbedre deres produkter med henblik på at minimere stråledosis til patienterne samtidig med at bevare eller forbedre billedkvaliteten. På trods af at røntgenteknologien teoretisk medfører en risiko for strålingsinducerede skader, er der stadigvæk en fordel ved brug af røntgen til diagnostiske formål, som overvejer denne risiko. Røntgenteknologierne er uundværlige, idet ikke-ioniserende teknologier som ultralyd- og MR undersøgelser ikke har vist sig at kunne erstattealle røntgenundersøgelser. Desuden har det vist sig at klinisk brug af røntgenteknologier steget igennem de seneste årtier, idet røntgenteknologier giver diagnostiske resultater, som ofte redder liv ved at diagnosticere livstruende sygdomme f.eks. af akut eller malign karakter. Der er nødvendigt at foretage optimering af røntgensystemer for at reducere stråledosis til patienterne og dermed minimere strålingsdosis. 2D/3D lavdosis slot scanner (LDSS) er et relativt nyt røntgen system, som udsætter patienterne for lavere stråledosis med samtidig bevaret uændret tilstrækkelig diagnostisk information sammenlignet med konventionel digital radiografi (DR). LDSS har ikke været optimeret og anvendt til udbredte kliniske undersøgelser for diagnostiske formål, men overvejende kun brugt til oversigtsbilleder af patienter med skoliose og måling af længden af underekstremiteter. I denne afhandling er foretaget en omfattende evaluering af billedkvalitet og strålingsbesparelse ved LDSS sammenlignet med konventionelle DR systemer. Der er desuden foretaget en optimering og evaluering af billedkvalitet samt strålingsbesparelse på LDSS ved thorax- og knæundersøgelser. Stråledosis og billedkvalitet ved LDSS er desuden sammenlignet med to forskellige konventionelle DR røntgensystemer. Denne Ph.d. afhandling består af tre studier med tre forskellige billedkvalitets evaluerings metoder.Formål var: 1) at evaluere billedkvaliteten samt undersøger om LDSS kan bruges til mere udbredte diagnostisk formål sammenlignet konventionelle DR røntgensystemer ved brug af tre forskellige billedkvalitets vurderingsteknikker. 2) At undersøge stråledosis besparelse ved LDSS i forhold til de konventionelle DR systemer, samt 3) At optimere kliniske protokoller på LDSS således at billedkvalitet ved LDSS var sammenligneligt med de konventionelle DR systemer. Hypotesen var, at LDSS kan give samme diagnostisk billedkvalitet som konventionelle DR-systemer ved anvendelse af lavere stråledosis til patienten.Materialer og metoder: For at kunne sammenligne billedkvaliteten og stråledosis ved LDSS med konventionelle røntgen systemer, blev der brugt to DR røntgensystemer fra to forskellige leverandører. I studie I af afhandlingen blevet antropomorft (alderson) fantombrugt til organdosis måling af thorax alle systemer. I knæ undersøgeler blev brugt et polymethylmethacrylat (PMMA) fantom på 20 cm i tykkelsen svarende til en gennemsnitlig voksen patientstørrelse også brugt til at evaluere kontrast-detalje opløsningen af systemerne i thorax. Et kontrast-detalje test objekt (CDRAD) 2.0 phantom og CDRAD v2.1.9 softwareanalyse blev brugt til at evaluere kontrast-detalje opløsningen af alle systemer i både thorax og knæ. I studie II af afhandlingen blev et thorax fantom med hybrid PMMA og aluminiumsfolier brugt til at evaluere den kvantitative billedkvalitet af thorax i alle systemer. I knæ undersøgelserne blev 15 cm PMMA brugt til at evaluere den kvantitative billedkvalitet i alle systemer. I studie III af afhandlingen, blev et antropomorft thorax (LungMan, Kyoto Kagaku Co., Ltd., Kyoto, Japan) med et ekstra fedtlag brugt til at producere et thorax billede til evaluering af visuel billedkvalitet af thorax for alle røntgen systemer. Et knæfantom medindsat naturlig knogle blev brugt til at evaluere den visuelle billedkvalitet af knæ protokoller i alle tre systemer. Monte Carlo-simuleringssoftwaren PCXMC blev brugt til at beregne den effektive dosis og organdosis for både knæ og thorax alle systemer. IQworks software blev brugt til at beregner de kvantitative parametre, herunder effektiv modulation transfer funktion og effektiv normalised noise power spektrum. Statistical Package for the Social Sciences, Release 26.0.0.0 software blev brugt til al statistisk analyse af afhandlingen. Det  statistiske signifikansniveau brugt i alle statistiske analyser var 5 %. Thermoluminescerende dosimetre (TLD) var brugt til at måleorgandoserne direkte i lungerne og skjoldbruskkirtlen i thorax.Den effektive dosis til patienter for både Thorax og knæblev estimeret ved hjælp af verificerede dosis arealprodukt værdier (DAP) fra alle systemer. En halvlede dosimeter blev brugt til måling af air kerma (AK) for at verificere systemernes DAP-målere. Den beregnede (simulerede) og den direkte målte organdosis for lungerne, skjoldbruskkirtlen og ekstremitetsknogler for både thorax og knæ blev sammenlignet på tværs af systemerne. Default dosis opsætningen af LDSS, som blev brugt til skoliose oversigtsbilleder og benlængde målinger, var signifikant lavere end ved DR-systemerne. Derfor blev stråledosis ved LDSS for både thorax og knæ optimeret. I forbindelse med denne undersøgelse. Dosisniveauet af LDSS blev øget for at give omtrent den samme diagnostiske information som i de konventionelle DR-systemer. I modsætning hertil blev den optimale rutinemæssigt anvendte dosisindstilling af konventionelle DR røntgensystemer anvendt uændret. Tre forskellige og væsentlige billedkvalitetsevalueringsteknikker blev brugt til at vurdere billedkvaliteten af LDSS sammenlignet med konventionelle DR røntgensystemer. Billedkvalitets-evalueringsmetoderne var baseret på både subjektive og objektive teknikker. Der blev optaget og indsamlet 470 røntgenbilleder til både billedkvalitets-evaluering og stråledosisberegning/måling i alle systemer og protokoller.Resultater: De optimerede scanningshastigheder for LDSS var speed 6 og 8 for henholdsvis thorax- og knæundersøgelser, med billedkvalitet sammenlignelig med DRsystemer. Default indstillet scan hastighed for LDSS var speed 4 og 6 for henholdsvis thorax- og knæundersøgelser. Effektiv dosis sammenlignings resultater har vist, at optimeret protokoller på LDSS udsætter patienterne for (41,7-42,6 % og 29,5-35,0 %) lavere effektive doser end konventionelle DR-røntgensystemer til henholdsvis thorax- og knæundersøgelser. LDSS gav også en signifikant (20-40%) lavere organdosis til patienterne end DRsystemerne. Billedkvalitetsresultater fra alle tre forskellige billedkvalitetsteknikker har vist, at de optimerede thorax- og knæ undersøgelser for LDSS har enten højere eller samme billedkvalitet end de konventionelle DR-systemer. Visual grading analysis (VGA)-analyseresultaterne har også vist god inter- og intra-observer enigheden for alle VGA-billedkvalitetskriterier for både thorax- og knæ undersøgelser.Konklusion: De overordnede resultater af disse tre forskellige billedkvalitetsevalueringsstudier viser, at LDSS har samme billedkvalitet som DR røntgensystemerne til både knæ- og thorax undersøgelser. LDSS har den fordel at den udsætter patienterne for en signifikant lavere stråledosis end DR røntgensystemerne. Derfor har LDSS demonstreret potentiale til at opnå billedkvalitet til diagnostisk brug i både thorax- og knæ undersøgelser under anvendelse af øget stråledosis.X-ray imaging technology uses ionising radiation and thus exposes the patients to radiation. X-ray vendors are constantly trying to improve their products with the intention of minimising radiation exposure to patients while at the same time, maintaining or improving image quality. Radiation exposure from the X-ray imaging modalities has the potential to damage the biological cells and is followed by the risk of radiation-induced cancers, and this should not be ignored. However, the diagnostic use of X-rays has great benefits that outweigh the potential risks. X-ray technology is highly clinically relevant and can save many patients’ lives by enabling the diagnosis of life-threatening diseases and is therefore indispensable for patient examinations. The use of X-ray technology in clinical settings has increased in recent decades, and optimising X-ray systems by reducing the radiation dose is still an essential task. The 2D/3D low-dose slot scanner (LDSS) imaging system is a relatively new X-ray imaging technology that exposes patients to lower radiation doses and at the same time provides sufficient diagnostic information compared to conventional X-ray imaging systems. The LDSS system has not been generally approved as a diagnostic tool for radiological diagnosis in several clinical settings, as the system is not optimised for these diagnostic purposes. So far, the LDSS systems has mainly been used to obtain overview images of patients with scoliosis and to measure the length of lower extremities, especially in children. In this thesis, a comprehensive investigation of image quality and radiation dose saving in the LDSS imaging system was conducted and the system was compared with conventional digital radiography (DR) X-ray systems. This thesis is a collection of three different studies using three different methods to evaluate image quality and to estimate the imaging system's radiation dose to patients. For each of these three studies, a scientific article was published in the field of medical imaging and in radiology journals. Aims: The aim of the thesis was to investigate the image quality and suitability of the LDSS imaging system for diagnostic purposes using three different image quality assessment techniques. The image quality achieved in the LDSS imaging system was compared with the image quality of two conventional DR X-ray systems through different image quality evaluation techniques. In addition, the radiation exposure to patients from the LDSS imaging system was optimised and compared to the conventional DR systems.The objective of this thesis was to investigate whether the LDSS imaging system could provide diagnostic images of the same quality as conventional DR systems without compromising image quality. Two DR X-ray systems from two different vendors were used to evaluate the image quality and radiation dose and to compare these with the LDSS imaging system. In Study I, an anthropomorphic phantom was used for organ dose measurement for the chest protocol in all systems. In Study I, a Polymethyl Methacrylate (PMMA) plate phantom of 20 cm equivalent to a typical average patient size was also used to evaluate contrast detail resolution of the systems in the chest protocol. A contrast-detail for radiography (CDRAD) 2.0 phantom and CDRAD v2.1.9 software analysis were used to evaluate the contrast detail resolution of the imaging system. In Study II, an in-house chest phantom with hybrid Polymethyl Methacrylate (PMMA) and aluminium foils was used to evaluate the quantitative image quality of the imaging systems and 15 cm PMMA was used to assess the contrast detail resolution of the systems in knee protocol. In Study III, an anthropomorphic chest phantom and a native-bone knee phantom were used to evaluate the visual image quality of the system. Monte Carlo simulation software PCXMC was used to calculate the effective dose and organ dose for both knee and chest protocols in all imaging systems. Statistical Package for the Social Sciences (SPSS), Release 26.0.0.0 software was used for all statistical analysis of thesis. The statistical significance level used in all analyses was 5%. Thermo-luminescent dosimeters (TLD) were used to measure the organ doses of the lungs and thyroid directly in the chest protocol. The effective dose of systems in both chest and knee protocols was estimated using verified dose area product (DAP) values from all of the imaging systems. However, a solid-state dosimeter was used to verify the DAP meters of the systems.A calculated (simulated) and a directly measured organ dose for the lungs, thyroids, and lower leg bones in both chest and knee protocols were compared across systems. The default dose setup of the LDSS imaging system, which was used for scoliosis overview images and leg length measurements, was significantly lower than in the DR systems. Therefore, the radiation exposure of the LDSS imaging systems for both chest and knee protocols were optimized. The dose level of the LDSS imaging system has been increased to provide approximately the same diagnostic information as in the conventional DR systems. In contrast, the optimal routinely used dose setting of conventional DR X-ray systems was used. Three different and essential image quality evaluations were used to assess the image quality of the LDSS imaging system compared with conventional DR imaging systems. These three image quality evaluation methods were performed in three separate studies: the technical (contrast detail resolution), quantitative, and visual grading analysis (VGA) image quality evaluation. The image quality evaluations methods were based on both subjective and objective techniques. In all three studies in this thesis, 468 images were acquired for both image quality assessment and radiation dose calculation/measurement in all imaging systems and protocols. For the visual image quality assessment, three experienced radiologists practising thoracic radiology who are specialised in the reporting of thoracic images visually scored 60 chest PA and LAT projection images for all imaging systems. However, two experienced diagnostic radiographers with postgraduate degrees in appendicular skeletal reporting and one research radiographer scored the 60 images of knee PA and LAT for all three imaging systems. The optimised scan speeds of the LDSS imaging system were speeds 6 and 8 for chest and knee protocols, respectively, with image quality comparable to that of DR systems. The default setting scan speeds of the LDSS imaging system were speed 4 and speed 6 for the chest and knee protocols, respectively. The dose comparison results obtained showed that LDSS imaging system exposed patients to significantly (41.–42.6% and 29.5–35.0%) lower effective dose than conventional DR X-ray systems for the chest and knee protocols, respectively. The LDSS imaging system also obtained a significantly (20- 40%) lower organ dose to the patients than with DR systems. The evaluated image quality results of all three different image quality studies have shown that the optimised chest and knee protocols for the LDSS imaging system have equal image quality to that of the conventional DR systems. The VGA analysis results have shown good inter-observer and intra-observer agreement for all VGA image quality criteria for both chest and knee protocols. The overall results of these three different image quality assessment studies show that the LDSS imaging system has equal image quality to the DR imaging system for both extremity and chest radiography. The LDSS imaging has the advantage of exposing patients to a lower radiation dose than do the DR systems. Thus, the LDSS imaging system has demonstrated the potential to obtain image quality for diagnosis in chest and knee protocols

Interlandmark measurements from lodox statscan images with application to femoral neck anteversion assessment

Includes abstract.Includes bibliographical references.Clinicians often take measurements between anatomical landmarks on X-ray radiographs for diagnosis and treatment planning, for example in orthopaedics and orthodontics. X-ray images, however, overlap three-dimensional internal structures onto a two-dimensional plane during image formation. Depth information is therefore lost and measurements do not truly reflect spatial relationships. The main aim of this study was to develop an inter-landmark measurement tool for the Lodox Statscan digital radiography system. X-ray stereophotogrammetry was applied to Statscan images to enable three-dimensional point localization for inter-landmark measurement using two-dimensional radiographs. This technique requires images of the anatomical region of interest to be acquired from different perspectives as well as a suitable calibration tool to map image coordinates to real world coordinates. The Statscan is suited to the technique because it is capable of axial rotations for multiview imaging. Three-dimensional coordinate reconstruction and inter-landmark measurements were taken using a planar object and a dry pelvis specimen in order to assess the intra-observer measurement accuracy, reliability and precision. The system yielded average (X, Y, Z) coordinate reconstruction accuracy of (0.08 0.12 0.34) mm and resultant coordinate reconstruction accuracy within 0.4mm (range 0.3mm – 0.6mm). Inter-landmark measurements within 2mm for lengths and 1.80 for angles were obtained, with average accuracies of 0.4mm (range 0.0mm – 2.0 mm) and 0.30 (range 0.0 – 1.8)0 respectively. The results also showed excellent overall precision of (0.5mm, 0.10) and were highly reliable when all landmarks were completely visible in both images. Femoral neck anteversion measurement on Statscan images was also explored using 30 dry right adult femurs. This was done in order to assess the feasibility of the algorithm for a clinical application. For this investigation, four methods were tested to determine the optimal landmarks for measurement and the measurement process involved calculation of virtual landmarks. The method that yielded the best results produced all measurements within 10 of reference values and the measurements were highly reliable with very good precision within 0.10. The average accuracy was within 0.40 (range 0.10 –0.80).In conclusion, X-ray stereophotogrammetry enables accurate, reliable and precise inter-landmark measurements for the Lodox Statscan X-ray imaging system. The machine may therefore be used as an inter-landmark measurement tool for routine clinical applications

Validity of a Quantitative Clinical Measurement Tool of Trunk Posture in Idiopathic Scoliosis

STUDY DESIGN: Concurrent validity between postural indices obtained from digital photographs (two-dimensional [2D]), surface topography imaging (three-dimensional [3D]), and radiographs. OBJECTIVE: To assess the validity of a quantitative clinical postural assessment tool of the trunk based on photographs (2D) as compared to a surface topography system (3D) as well as indices calculated from radiographs. SUMMARY OF BACKGROUND DATA: To monitor progression of scoliosis or change in posture over time in young persons with idiopathic scoliosis (IS), noninvasive and nonionizing methods are recommended. In a clinical setting, posture can be quite easily assessed by calculating key postural indices from photographs. METHODS: Quantitative postural indices of 70 subjects aged 10 to 20 years old with IS (Cobb angle, 15 degrees -60 degrees) were measured from photographs and from 3D trunk surface images taken in the standing position. Shoulder, scapula, trunk list, pelvis, scoliosis, and waist angles indices were calculated with specially designed software. Frontal and sagittal Cobb angles and trunk list were also calculated on radiographs. The Pearson correlation coefficients (r) was used to estimate concurrent validity of the 2D clinical postural tool of the trunk with indices extracted from the 3D system and with those obtained from radiographs. RESULTS: The correlation between 2D and 3D indices was good to excellent for shoulder, pelvis, trunk list, and thoracic scoliosis (0.81>rr<0.56; P<0.05). The correlation between 2D and radiograph spinal indices was fair to good (-0.33 to -0.80 with Cobb angles and 0.76 for trunk list; P<0.05). CONCLUSION: This tool will facilitate clinical practice by monitoring trunk posture among persons with IS. Further, it may contribute to a reduction in the use of radiographs to monitor scoliosis progression.CIHR / IRS