Solid rocket motor certification to meet space shuttle requirements from challenge to achievement

NASA Technical Reports Server (NTRS)

Miller, J. Q.; Kilminster, J. C.

1985-01-01

Three solid rocket motor (SRM) design requirements for the Space Shuttle were discussed. No existing solid rocket motor experience was available for the requirement for a thrust-time trace, twenty uses for the principle hardware, and a moveable nozzle with an 8 deg. omnivaxial vectoring capability. The solutions to these problems are presented.

78 FR 48608 - Drawbridge Operation Regulation; Atlantic Intracoastal Waterway (AIWW), Chesapeake, VA

Federal Register 2010, 2011, 2012, 2013, 2014

2013-08-09

... maintenance of the moveable spans on the structure. The current operating schedule for the bridge is set out... deviation from the operating schedule that governs the operation of the I64 Bridge across the Atlantic... necessary to facilitate maintenance work on the moveable spans. This temporary deviation allows the...

Design and realization of the real-time spectrograph controller for LAMOST based on FPGA

NASA Astrophysics Data System (ADS)

Wang, Jianing; Wu, Liyan; Zeng, Yizhong; Dai, Songxin; Hu, Zhongwen; Zhu, Yongtian; Wang, Lei; Wu, Zhen; Chen, Yi

2008-08-01

A large Schmitt reflector telescope, Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST), is being built in China, which has effective aperture of 4 meters and can observe the spectra of as many as 4000 objects simultaneously. To fit such a large amount of observational objects, the dispersion part is composed of a set of 16 multipurpose fiber-fed double-beam Schmidt spectrographs, of which each has about ten of moveable components realtimely accommodated and manipulated by a controller. An industrial Ethernet network connects those 16 spectrograph controllers. The light from stars is fed to the entrance slits of the spectrographs with optical fibers. In this paper, we mainly introduce the design and realization of our real-time controller for the spectrograph, our design using the technique of System On Programmable Chip (SOPC) based on Field Programmable Gate Array (FPGA) and then realizing the control of the spectrographs through NIOSII Soft Core Embedded Processor. We seal the stepper motor controller as intellectual property (IP) cores and reuse it, greatly simplifying the design process and then shortening the development time. Under the embedded operating system μC/OS-II, a multi-tasks control program has been well written to realize the real-time control of the moveable parts of the spectrographs. At present, a number of such controllers have been applied in the spectrograph of LAMOST.

Mobile lighting apparatus

DOEpatents

Roe, George Michael; Klebanoff, Leonard Elliott; Rea, Gerald W; Drake, Robert A; Johnson, Terry A; Wingert, Steven John; Damberger, Thomas A; Skradski, Thomas J; Radley, Christopher James; Oros, James M; Schuttinger, Paul G; Grupp, David J; Prey, Stephen Carl

2013-05-14

A mobile lighting apparatus includes a portable frame such as a moveable trailer or skid having a light tower thereon. The light tower is moveable from a stowed position to a deployed position. A hydrogen-powered fuel cell is located on the portable frame to provide electrical power to an array of the energy efficient lights located on the light tower.

Compact electrostatic comb actuator

DOEpatents

Rodgers, M. Steven; Burg, Michael S.; Jensen, Brian D.; Miller, Samuel L.; Barnes, Stephen M.

2000-01-01

A compact electrostatic comb actuator is disclosed for microelectromechanical (MEM) applications. The actuator is based upon a plurality of meshed electrostatic combs, some of which are stationary and others of which are moveable. One or more restoring springs are fabricated within an outline of the electrostatic combs (i.e. superposed with the moveable electrostatic combs) to considerably reduce the space required for the actuator. Additionally, a truss structure is provided to support the moveable electrostatic combs and prevent bending or distortion of these combs due to unbalanced electrostatic forces or external loading. The truss structure formed about the moveable electrostatic combs allows the spacing between the interdigitated fingers of the combs to be reduced to about one micron or less, thereby substantially increasing the number of active fingers which can be provided in a given area. Finally, electrostatic shields can be used in the actuator to substantially reduce unwanted electrostatic fields to further improve performance of the device. As a result, the compact electrostatic comb actuator of the present invention occupies only a fraction of the space required for conventional electrostatic comb actuators, while providing a substantial increase in the available drive force (up to one-hundred times).

Innovative anisotropic phantoms for calibration of diffusion tensor imaging sequences.

PubMed

Kłodowski, Krzysztof; Krzyżak, Artur Tadeusz

2016-05-01

The paper describes a novel type of anisotropic phantoms designed for b-matrix spatial distribution diffusion tensor imaging (BSD-DTI). Cubic plate anisotropic phantom, cylinder capillary phantom and water reference phantom are described as a complete set necessary for calibration, validation and normalization of BSD-DTI. An innovative design of the phantoms basing on enclosing the anisotropic cores in glass balls filled with liquid made for the first time possible BSD calibration with usage of echo planar imaging (EPI) sequence. Susceptibility artifacts prone to occur in EPI sequences were visibly reduced in the central region of the phantoms. The phantoms were designed for usage in a clinical scanner's head coil, but can be scaled for other coil or scanner types. The phantoms can be also used for a pre-calibration of imaging of other types of phantoms having more specific applications. Copyright © 2015 Elsevier Inc. All rights reserved.

COMPARTMENTALIZED PHANTOMS FOR THE STANDARD MAN, ADOLESCENT AND CHILD

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hayes, R.L.; Brucer, M.

A compartmentalized phantom for the standard man was designed and built of readily available and inexpensive materials. Similar phantoms were also designed for an adolescent and a child. The basic emphasis in the designs is on general utility so that a variety of different dosemeasurement techniques could be used on the same phantom. The designs are, however, in reasonable agreement with authropometric data reported in the literature. The phantoms proved to be extremely useful in depth-dose and energy-absorption measurements for total-body irradiation therapy. Dose measurements with beam teletherapy, brachytherapy devices, and internally distributed radioisotopes were also made. (auth)

Design and evaluation of corn starch-bonded Rhizophora spp. particleboard phantoms for SPECT/CT imaging

NASA Astrophysics Data System (ADS)

Hamid, Puteri Nor Khatijah Abd; Yusof, Mohd Fahmi Mohd; Aziz Tajuddin, Abd; Hashim, Rokiah; Zainon, Rafidah

2018-01-01

The aim of this study was to design and evaluate of corn starch-bonded Rhizophora spp. particleboards as phantom for SPECT/CT imaging. The phantom was designed according to the Jaszczak phantom commonly used in SPECT imaging with dimension of 22 cm diameter and 18 cm length. Six inserts with different diameter were made for insertion of vials filled with 1.6 µCi/ml of 99mTc unsealed source. The particleboard phantom was scanned using SPECT/CT imaging protocol. The contrast of each vial for particleboards phantom were calculated based on the ratio of counts in radionuclide volume and phantom background and compared to Perspex® and water phantom. The results showed that contrast values for each vial in particleboard phantomis near to 1.0 and in good agreement with Perspex® and water phantoms as common phantom materials for SPECT/CT. The paired sample t-test result showed no significant difference of contrast values between images in particleboard phantoms and that in water. The overall results showed the potential of corn starch-bonded Rhizophora spp. as phantom for quality control and dosimetry works in SPECT/CT imaging.

Compound semiconductor optical waveguide switch

DOEpatents

Spahn, Olga B.; Sullivan, Charles T.; Garcia, Ernest J.

2003-06-10

An optical waveguide switch is disclosed which is formed from III-V compound semiconductors and which has a moveable optical waveguide with a cantilevered portion that can be bent laterally by an integral electrostatic actuator to route an optical signal (i.e. light) between the moveable optical waveguide and one of a plurality of fixed optical waveguides. A plurality of optical waveguide switches can be formed on a common substrate and interconnected to form an optical switching network.

Apparatus and method for sensing motion in a microelectro-mechanical system

DOEpatents

Dickey, Fred M.; Holswade, Scott C.

1999-01-01

An apparatus and method are disclosed for optically sensing motion in a microelectromechanical system (also termed a MEMS device) formed by surface micromachining or LIGA. The apparatus operates by reflecting or scattering a light beam off a corrugated surface (e.g. gear teeth or a reference feature) of a moveable member (e.g. a gear, rack or linkage) within the MEMS device and detecting the reflected or scattered light. The apparatus can be used to characterize a MEMS device, measuring one or more performance characteristic such as spring and damping coefficients, torque and friction, or uniformity of motion of the moveable member. The apparatus can also be used to determine the direction and extent of motion of the moveable member; or to determine a particular mechanical state that a MEMS device is in. Finally, the apparatus and method can be used for providing feedback to the MEMS device to improve performance and reliability.

Solid anthropomorphic infant whole body DXA phantom: Design, evaluation, and multisite testing

USDA-ARS?s Scientific Manuscript database

Dual energy X-ray absorptiometry (DXA) requires phantoms for quality control and cross-calibration. No commercially available phantoms are designed specifically for infant whole-body scanning. We fabricated a phantom closely matching a 7-kg human infant in body habitus using PVC, nylon-mix, and poly...

Poster - Thur Eve - 48: An inexpensive and convenient phantom for quality assurance in image guidance based radiosurgery.

PubMed

Soisson, E

2012-07-01

This work describes the design and use of an inexpensive phantom designed for precision measurements in radiosurgery quality assurance. The main features of this simple phantom include its solid water construction, interchangeable ion chamber holders and film registration system, thus allowing for measurement of small fields with several detectors using the same phantom. The entire phantom was constructed using one 30cm × 30cm × 3cm slab of solid water. The phantom contains a slot that allows for the placement of two small volume ion chambers (liquid and A1SL) via custom inserts near the center of the phantom. In addition, the plug can be filled for film measurements. The phantom can be split down the center to allow for the placement of a film. As opposed to registering film to room based markers, such as lasers, the phantom contains radio-opaque fiducials that puncture the film while also providing a method to register the film images to exported dose planes. In addition to the markers used for film registration, the phantom contains several external beebees that can be used to avoid ambiguity in image registration when using image guidance for setup. This simple phantom contains many features of other much more expensive phantoms designed for this purpose and has been found to be very useful clinically and in departmental research. The key elements of this phantom could be included in several other designs allowing it to be reproduced in other centers. © 2012 American Association of Physicists in Medicine.

Common Aperture Techniques for Imaging Electro-Optical Sensors (CATIES).

DTIC Science & Technology

1980-02-01

milliradians ) at the 5.33:1 zoom point. The zoom optics contain five elements with two moveable air -spaced doublets for accomplishing the zoom function...included in the electrical and optical design but due to funding limitations, system safety requirements during the testing phase and lack of long-term...determined during the system testing phase to be conducted by the Air Force. Limited electronic signal processing (split screen and video mix) was

The design and fabrication of two portal vein flow phantoms by different methods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yunker, Bryan E., E-mail: bryan.yunker@ucdenver.edu; Lanning, Craig J.; Shandas, Robin

2014-02-15

Purpose: This study outlines the design and fabrication techniques for two portal vein flow phantoms. Methods: A materials study was performed as a precursor to this phantom fabrication effort and the desired material properties are restated for continuity. A three-dimensional portal vein pattern was created from the Visual Human database. The portal vein pattern was used to fabricate two flow phantoms by different methods with identical interior surface geometry using computer aided design software tools and rapid prototyping techniques. One portal flow phantom was fabricated within a solid block of clear silicone for use on a table with Ultrasound ormore » within medical imaging systems such as MRI, CT, PET, or SPECT. The other portal flow phantom was fabricated as a thin walled tubular latex structure for use in water tanks with Ultrasound imaging. Both phantoms were evaluated for usability and durability. Results: Both phantoms were fabricated successfully and passed durability criteria for flow testing in the next project phase. Conclusions: The fabrication methods and materials employed for the study yielded durable portal vein phantoms.« less

Technical note: A 3D-printed phantom for routine accuracy check of Gamma Knife Icon HDMM system.

PubMed

Wu, Chuan; Radevic, Marlyn B; Glass, Jennifer S; Skubic, Stan E

2018-05-23

To report a novel 3D-printed device ("SH phantom") that is designed for routine accuracy check of the Gamma Knife Icon High Definition Motion Management (HDMM) system. SH phantom was designed using tinkerCAD software and printed on a commercial 3D printer. We evaluated the SH phantom on our Gamma Knife Icon unit regarding its usability and accuracy for routine HDMM QA. Single-axis and multiple-axis measurements validated the SH phantom design and implementation. An HDMM QA accuracy of 0.22 mm or better along single axis was found using SH phantom. The SH phantom proved to be a quick and simple tool to use to perform the HDMM system QA. The SH phantom was tested successfully and adopted by us as part of monthly QA for the Gamma Knife Icon. © 2018 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

Design and fabrication of a realistic anthropomorphic heterogeneous head phantom for MR purposes

PubMed Central

Wood, Sossena; Krishnamurthy, Narayanan; Santini, Tales; Raval, Shailesh; Farhat, Nadim; Holmes, John Andy; Ibrahim, Tamer S.

2017-01-01

Objective The purpose of this study is to design an anthropomorphic heterogeneous head phantom that can be used for MRI and other electromagnetic applications. Materials and methods An eight compartment, physical anthropomorphic head phantom was developed from a 3T MRI dataset of a healthy male. The designed phantom was successfully built and preliminarily evaluated through an application that involves electromagnetic-tissue interactions: MRI (due to it being an available resource). The developed phantom was filled with media possessing electromagnetic constitutive parameters that correspond to biological tissues at ~297 MHz. A preliminary comparison between an in-vivo human volunteer (based on whom the anthropomorphic head phantom was created) and various phantoms types, one being the anthropomorphic heterogeneous head phantom, were performed using a 7 Tesla human MRI scanner. Results Echo planar imaging was performed and minimal ghosting and fluctuations were observed using the proposed anthropomorphic phantom. The magnetic field distributions (during MRI experiments at 7 Tesla) and the scattering parameter (measured using a network analyzer) were most comparable between the anthropomorphic heterogeneous head phantom and an in-vivo human volunteer. Conclusion The developed anthropomorphic heterogeneous head phantom can be used as a resource to various researchers in applications that involve electromagnetic-biological tissue interactions such as MRI. PMID:28806768

The Human Powered Submarine Team of Virginia Tech Propulsion System Design Final Report

NASA Technical Reports Server (NTRS)

An, Eric; Bennett, Matt; Callis, Ron; Chen, Chester; Lee, John; Milan-Williams, Kristy

1999-01-01

The Human Powered Submarine Team has been in existence at Virginia Tech since its conception in 1993. Since then, it has served as a way for engineering students from many different disciplines to implement design conception and realization. The first submarine built was Phantom 1, a two-man submarine made of fiberglass. After construction was complete, Phantom 1 was ready for racing, but, unfortunately, suffered fatal problems come race time. The submarine team slowed down a bit after experiencing racing problems, but was revived in 1995 when design efforts for a new two-man submarine, the Phantom 2 commence. The propulsion system consisted of a chain and gear drive system using an ultra-light helicopter tail rotor for a propeller. Although the team learned valuable lessons as a result of Phantom 1's problems, Phantom 2 still experiences problems at races. After various parts of Phantom 2 are redesigned, it is once again ready for racing and proves that the redesign was well worth the time and effort. In 1997, Phantom 2 not only finishes its first race, held in San Diego, California, but comes in third. This success sparks yet another revival of the submarine team and design for the team's current project, the Phantom 3, a one-man submarine, is started. In 1998, the plug for Phantom 3 is built and the hull is constructed. With so many past problems from which to learn, Phantom 3 promises to be the fastest and best-designed submarine the team has developed thus far. The current speed world-record is 7 knots.

Technical Note: A new phantom design for routine testing of Doppler ultrasound.

PubMed

Grice, J V; Pickens, D R; Price, R R

2016-07-01

The objective of this project is to demonstrate the principle and operation for a simple, inexpensive, and highly portable Doppler ultrasound quality assurance (QA) phantom intended for routine QA testing. A prototype phantom has been designed, fabricated, and evaluated. The phantom described here is powered by gravity alone, requires no external equipment for operation, and produces a stable fluid velocity useful for quality assurance. Many commercially available Doppler ultrasound testing systems can suffer from issues such as a lengthy setup, prohibitive cost, nonportable size, or difficulty in use. This new phantom design aims to address some of these problems and create a phantom appropriate for assessing Doppler ultrasound stability. The phantom was fabricated using a 3D printer. The basic design of the phantom is to provide gravity-powered flow of a Doppler fluid between two reservoirs. The printed components were connected with latex tubing and then seated in a tissue mimicking gel. Spectral Doppler waveforms were sampled to evaluate variations in the data, and the phantom was evaluated using high frame rate video to find an alternate measure of mean fluid velocity flowing in the phantom. The current system design maintains stable flow from one reservoir to the other for approximately 7 s. Color Doppler imaging of the phantom was found to be qualitatively consistent with laminar flow. Using pulsed spectral Doppler, the average fluid velocity from a sample volume approximately centered in the synthetic vessel was measured to be 56 cm/s with a standard deviation of 3.2 cm/s across 118 measurements. An independent measure of the average fluid velocity was measured to be 51.9 cm/s with a standard deviation of 0.7 cm/s over 4 measurements. The developed phantom provides stable fluid flow useful for frequent clinical Doppler ultrasound testing and attempts to address several obstacles facing Doppler phantom testing. Such an ultrasound phantom can make routine testing more approachable for institutions that wish to initiate a Doppler QA program or complement a previously existing QA program.

Control System for Prosthetic Devices

NASA Technical Reports Server (NTRS)

Bozeman, Richard J. (Inventor)

1996-01-01

A control system and method for prosthetic devices is provided. The control system comprises a transducer for receiving movement from a body part for generating a sensing signal associated with that of movement. The sensing signal is processed by a linearizer for linearizing the sensing signal to be a linear function of the magnitude of the distance moved by the body part. The linearized sensing signal is normalized to be a function of the entire range of body part movement from the no-shrug position of the moveable body part through the full-shrg position of the moveable body part. The normalized signal is divided into a plurality of discrete command signals. The discrete command signals are used by typical converter devices which are in operational association with the prosthetic device. The converter device uses the discrete command signals for driving the moveable portions of the prosthetic device and its sub-prosthesis. The method for controlling a prosthetic device associated with the present invention comprises the steps of receiving the movement from the body part, generating a sensing signal in association with the movement of the body part, linearizing the sensing signal to be a linear function of the magnitude of the distance moved by the body part, normalizing the linear signal to be a function of the entire range of the body part movement, dividing the normalized signal into a plurality of discrete command signals, and implementing the plurality of discrete command signals for driving the respective moveable prosthesis device and its sub-prosthesis.

A novel breast software phantom for biomechanical modeling of elastography.

PubMed

Bhatti, Syeda Naema; Sridhar-Keralapura, Mallika

2012-04-01

In developing breast imaging technologies, testing is done with phantoms. Physical phantoms are normally used but their size, shape, composition, and detail cannot be modified readily. These difficulties can be avoided by creating a software breast phantom. Researchers have created software breast phantoms using geometric and/or mathematical methods for applications like image fusion. The authors report a 3D software breast phantom that was built using a mechanical design tool, to investigate the biomechanics of elastography using finite element modeling (FEM). The authors propose this phantom as an intermediate assessment tool for elastography simulation; for use after testing with commonly used phantoms and before clinical testing. The authors design the phantom to be flexible in both, the breast geometry and biomechanical parameters, to make it a useful tool for elastography simulation. The authors develop the 3D software phantom using a mechanical design tool based on illustrations of normal breast anatomy. The software phantom does not use geometric primitives or imaging data. The authors discuss how to create this phantom and how to modify it. The authors demonstrate a typical elastography experiment of applying a static stress to the top surface of the breast just above a simulated tumor and calculate normal strains in 3D and in 2D with plane strain approximations with linear solvers. In particular, they investigate contrast transfer efficiency (CTE) by designing a parametric study based on location, shape, and stiffness of simulated tumors. The authors also compare their findings to a commonly used elastography phantom. The 3D breast software phantom is flexible in shape, size, and location of tumors, glandular to fatty content, and the ductal structure. Residual modulus, maps, and profiles, served as a guide to optimize meshing of this geometrically nonlinear phantom for biomechanical modeling of elastography. At best, low residues (around 1-5 KPa) were found within the phantom while errors were elevated (around 10-30 KPa) at tumor and lobule boundaries. From our FEM analysis, the breast phantom generated a superior CTE in both 2D and in 3D over the block phantom. It also showed differences in CTE values and strain contrast for deep and shallow tumors and showed significant change in CTE when 3D modeling was used. These changes were not significant in the block phantom. Both phantoms, however, showed worsened CTE values for increased input tumor-background modulus contrast. Block phantoms serve as a starting tool but a next level phantom, like the proposed breast phantom, will serve as a valuable intermediate for elastography simulation before clinical testing. Further, given the CTE metrics for the breast phantom are superior to the block phantom, and vary for tumor shape, location, and stiffness, these phantoms would enhance the study of elastography contrast. Further, the use of 2D phantoms with plane strain approximations overestimates the CTE value when compared to the true CTE achieved with 3D models. Thus, the use of 3D phantoms, like the breast phantom, with no approximations, will assist in more accurate estimation of modulus, especially valuable for 3D elastography systems.

Gas Turbine Engine Having Fan Rotor Driven by Turbine Exhaust and with a Bypass

NASA Technical Reports Server (NTRS)

Suciu, Gabriel L. (Inventor); Chandler, Jesse M. (Inventor)

2016-01-01

A gas turbine engine has a core engine incorporating a core engine turbine. A fan rotor is driven by a fan rotor turbine. The fan rotor turbine is in the path of gases downstream from the core engine turbine. A bypass door is moveable from a closed position at which the gases from the core engine turbine pass over the fan rotor turbine, and moveable to a bypass position at which the gases are directed away from the fan rotor turbine. An aircraft is also disclosed.

Rub tolerant shroud

NASA Technical Reports Server (NTRS)

Lenahan, Dean T. (Inventor); Gay, Jr., Charles H. (Inventor)

1985-01-01

A seal structure between first and second relatively moveable members for preventing gas flow in the space between the members and transverse to their general direction of motion is disclosed. The seal structure includes a plurality of substantially parallel strips within 30.degree. of normal to the radial plane generally containing these first and second relatively moveable members. The strips are thin and closely spaced and arranged so that one strip edge is attached to the first member and another edge is free to resiliently deflect when in rubbing contact with the second member.

SU-E-I-24: Design and Fabrication of a Multi-Functional Neck and Thyroid Phantom for Medical Dosimetry and Calibration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mehdizadeh, S; Sina, S; Karimipourfard, M

Purpose: The purpose of this study is the design and fabrication of a multipurpose anthropomorphic neck and thyroid phantom for use in medical applications (i.e. quality control of images in nuclear medicine, and dosimetry). Methods: The designed neck phantom is composed of seven elliptic cylindrical slices with semi-major axis of 14 and semi-minor axis of 12.5 cm, each having the thickness of 2cm. Thyroid gland, bony part of the neck, and the wind pipe were also built inside the neck phantom. Results: The phantom contains some removable plugs,inside and at its surface to accommodate the TLD chips with different shapesmore » and dimensions, (i.e. rod, cylindrical and cubical TLD chips)for the purpose of medical dosimetry (i.e. in radiology, radiotherapy, and nuclear medicine). For the purpose of quality control of images in nuclear medicine, the removable thyroid gland was built to accommodate the radioactive iodine. The female and male thyroid glands were built in two sizes separately. Conclusion: The designed phantom is a multi-functional phantom which is applicable for dosimetry in diagnostic radiology, radiotherapy, and quality control of images in nuclear medicine.« less

A suite of phantom-based test methods for assessing image quality of photoacoustic tomography systems

NASA Astrophysics Data System (ADS)

Vogt, William C.; Jia, Congxian; Wear, Keith A.; Garra, Brian S.; Pfefer, T. Joshua

2017-03-01

As Photoacoustic Tomography (PAT) matures and undergoes clinical translation, objective performance test methods are needed to facilitate device development, regulatory clearance and clinical quality assurance. For mature medical imaging modalities such as CT, MRI, and ultrasound, tissue-mimicking phantoms are frequently incorporated into consensus standards for performance testing. A well-validated set of phantom-based test methods is needed for evaluating performance characteristics of PAT systems. To this end, we have constructed phantoms using a custom tissue-mimicking material based on PVC plastisol with tunable, biologically-relevant optical and acoustic properties. Each phantom is designed to enable quantitative assessment of one or more image quality characteristics including 3D spatial resolution, spatial measurement accuracy, ultrasound/PAT co-registration, uniformity, penetration depth, geometric distortion, sensitivity, and linearity. Phantoms contained targets including high-intensity point source targets and dye-filled tubes. This suite of phantoms was used to measure the dependence of performance of a custom PAT system (equipped with four interchangeable linear array transducers of varying design) on design parameters (e.g., center frequency, bandwidth, element geometry). Phantoms also allowed comparison of image artifacts, including surface-generated clutter and bandlimited sensing artifacts. Results showed that transducer design parameters create strong variations in performance including a trade-off between resolution and penetration depth, which could be quantified with our method. This study demonstrates the utility of phantom-based image quality testing in device performance assessment, which may guide development of consensus standards for PAT systems.

Spatial and rotational quality assurance of 6DOF patient tracking systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Belcher, Andrew H.; Liu, Xinmin; Grelewicz, Zachary

Purpose: External tracking systems used for patient positioning and motion monitoring during radiotherapy are now capable of detecting both translations and rotations. In this work, the authors develop a novel technique to evaluate the 6 degree of freedom 6(DOF) (translations and rotations) performance of external motion tracking systems. The authors apply this methodology to an infrared marker tracking system and two 3D optical surface mapping systems in a common tumor 6DOF workspace. Methods: An in-house designed and built 6DOF parallel kinematics robotic motion phantom was used to perform motions with sub-millimeter and subdegree accuracy in a 6DOF workspace. An infraredmore » marker tracking system was first used to validate a calibration algorithm which associates the motion phantom coordinate frame to the camera frame. The 6DOF positions of the mobile robotic system in this space were then tracked and recorded independently by an optical surface tracking system after a cranial phantom was rigidly fixed to the moveable platform of the robotic stage. The calibration methodology was first employed, followed by a comprehensive 6DOF trajectory evaluation, which spanned a full range of positions and orientations in a 20 × 20 × 16 mm and 5° × 5° × 5° workspace. The intended input motions were compared to the calibrated 6DOF measured points. Results: The technique found the accuracy of the infrared (IR) marker tracking system to have maximal root-mean square error (RMSE) values of 0.18, 0.25, 0.07 mm, 0.05°, 0.05°, and 0.09° in left–right (LR), superior–inferior (SI), anterior–posterior (AP), pitch, roll, and yaw, respectively, comparing the intended 6DOF position and the measured position by the IR camera. Similarly, the 6DOF RSME discrepancy for the HD optical surface tracker yielded maximal values of 0.46, 0.60, 0.54 mm, 0.06°, 0.11°, and 0.08° in LR, SI, AP, pitch, roll, and yaw, respectively, over the same 6DOF evaluative workspace. An earlier generation 3D optical surface tracking unit was observed to have worse tracking capabilities than both the IR camera unit and the newer 3D surface tracking system with maximal RMSE of 0.69, 0.74, 0.47 mm, 0.28°, 0.19°, and 0.18°, in LR, SI, AP, pitch, roll, and yaw, respectively, in the same 6DOF evaluation space. Conclusions: The proposed technique was found to be effective at evaluating the performance of 6DOF patient tracking systems. All observed optical tracking systems were found to exhibit tracking capabilities at the sub-millimeter and subdegree level within a 6DOF workspace.« less

Building and assessing anatomically relevant phantoms for neonatal transcranial ultrasound

NASA Astrophysics Data System (ADS)

Memoli, G.; Gatto, M.; Sadhoo, N.; Gélat, P.; Harris, R. A.; Shaw, A.

2011-02-01

This study describes the design and construction of a clinically relevant phantom to survey the temperature increase caused by ultrasound equipment, as currently used in neonatal head-scanning in the UK. The phantom is an ellipsoid of bone-mimic material, filled with brain-mimic; a circular hole in the external surface mimicks the fontanel, through which most clinically relevant scans are made. Finite-element simulations were used to identify possible hot spots and decide the most effective thermocouple positions within the phantom to investigate temperature rise during a typical scan. Novel materials were purposively designed to simulate key acoustic and thermal properties. Three Dimensional Printing (3DP) was employed for the fabrication of the skull phantom, and a specific strategy was successfully pursued to embed a thermocouple within the 3DP skull phantom during the manufacturing process. An in-process Non-Destructive Analysis (NDA) was used to assess the correct position of the deposited thermocouple inside the fabricated skull phantom. The temperature increase in the phantom for a typical trans-fontanellar scan is also presented here. The current phantom will be used in a hospital survey in the UK and, in its final design, will allow for a more reliable evaluation of ultrasound heating than is currently possible.

SU-E-J-49: Design and Fabrication of Custom 3D Printed Phantoms for Radiation Therapy Research and Quality Assurance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jenkins, C; Xing, L

2015-06-15

Purpose The rapid proliferation of affordable 3D printing techniques has enabled the custom fabrication of items ranging from paper weights to medical implants. This study investigates the feasibility of utilizing the technology for developing novel phantoms for use in radiation therapy quality assurance (QA) procedures. Methods A phantom for measuring the geometric parameters of linear accelerator (LINAC) on-board imaging (OBI) systems was designed using SolidWorks. The design was transferred to a 3D printer and fabricated using a fused deposition modeling (FDM) technique. Fiducials were embedded in the phantom by placing 1.6 mm diameter steel balls in predefined holes and securingmore » them with silicone. Several MV and kV images of the phantom were collected and the visibility and geometric accuracy were evaluated. A second phantom, for use in the experimental evaluation of a high dose rate (HDR) brachytherapy dosimeter, was designed to secure several applicator needles in water. The applicator was fabricated in the same 3D printer and used for experiments. Results The general accuracy of printed parts was determined to be 0.1 mm. The cost of materials for the imaging and QA phantoms were $22 and $5 respectively. Both the plastic structure and fiducial markers of the imaging phantom were visible in MV and kV images. Fiducial marker locations were determined to be within 1mm of desired locations, with the discrepancy being attributed to the fiducial attachment process. The HDR phantom secured the applicators within 0.5 mm of the desired locations. Conclusion 3D printing offers an inexpensive method for fabricating custom phantoms for use in radiation therapy quality assurance. While the geometric accuracy of such parts is limited compared to more expensive methods, the phantoms are still highly functional and provide a unique opportunity for rapid fabrication of custom phantoms for use in radiation therapy QA and research.« less

Comprehensive quality assurance phantom for cardiovascular imaging systems

NASA Astrophysics Data System (ADS)

Lin, Pei-Jan P.

1998-07-01

With the advent of high heat loading capacity x-ray tubes, high frequency inverter type generators, and the use of spectral shaping filters, the automatic brightness/exposure control (ABC) circuit logic employed in the new generation of angiographic imaging equipment has been significantly reprogrammed. These new angiographic imaging systems are designed to take advantage of the power train capabilities to yield higher contrast images while maintaining, or lower, the patient exposure. Since the emphasis of the imaging system design has been significantly altered, the system performance parameters one is interested and the phantoms employed for the quality assurance must also change in order to properly evaluate the imaging capability of the cardiovascular imaging systems. A quality assurance (QA) phantom has been under development in this institution and was submitted to various interested organizations such as American Association of Physicists in Medicine (AAPM), Society for Cardiac Angiography & Interventions (SCA&I), and National Electrical Manufacturers Association (NEMA) for their review and input. At the same time, in an effort to establish a unified standard phantom design for the cardiac catheterization laboratories (CCL), SCA&I and NEMA have formed a joint work group in early 1997 to develop a suitable phantom. The initial QA phantom design has since been accepted to serve as the base phantom by the SCA&I- NEMA Joint Work Group (JWG) from which a comprehensive QA Phantom is being developed.

An open source, 3D printed preclinical MRI phantom for repeated measures of contrast agents and reference standards.

PubMed

Cox, B L; Ludwig, K D; Adamson, E B; Eliceiri, K W; Fain, S B

2018-03-01

In medical imaging, clinicians, researchers and technicians have begun to use 3D printing to create specialized phantoms to replace commercial ones due to their customizable and iterative nature. Presented here is the design of a 3D printed open source, reusable magnetic resonance imaging (MRI) phantom, capable of flood-filling, with removable samples for measurements of contrast agent solutions and reference standards, and for use in evaluating acquisition techniques and image reconstruction performance. The phantom was designed using SolidWorks, a computer-aided design software package. The phantom consists of custom and off-the-shelf parts and incorporates an air hole and Luer Lock system to aid in flood filling, a marker for orientation of samples in the filled mode and bolt and tube holes for assembly. The cost of construction for all materials is under $90. All design files are open-source and available for download. To demonstrate utility, B 0 field mapping was performed using a series of gadolinium concentrations in both the unfilled and flood-filled mode. An excellent linear agreement (R 2 >0.998) was observed between measured relaxation rates (R 1 /R 2 ) and gadolinium concentration. The phantom provides a reliable setup to test data acquisition and reconstruction methods and verify physical alignment in alternative nuclei MRI techniques (e.g. carbon-13 and fluorine-19 MRI). A cost-effective, open-source MRI phantom design for repeated quantitative measurement of contrast agents and reference standards in preclinical research is presented. Specifically, the work is an example of how the emerging technology of 3D printing improves flexibility and access for custom phantom design.

Double acting bit holder

DOEpatents

Morrell, Roger J.; Larson, David A.; Ruzzi, Peter L.

1994-01-01

A double acting bit holder that permits bits held in it to be resharpened during cutting action to increase energy efficiency by reducing the amount of small chips produced. The holder consist of: a stationary base portion capable of being fixed to a cutter head of an excavation machine and having an integral extension therefrom with a bore hole therethrough to accommodate a pin shaft; a movable portion coextensive with the base having a pin shaft integrally extending therefrom that is insertable in the bore hole of the base member to permit the moveable portion to rotate about the axis of the pin shaft; a recess in the movable portion of the holder to accommodate a shank of a bit; and a biased spring disposed in adjoining openings in the base and moveable portions of the holder to permit the moveable portion to pivot around the pin shaft during cutting action of a bit fixed in a turret to allow front, mid and back positions of the bit during cutting to lessen creation of small chip amounts and resharpen the bit during excavation use.

TU-H-206-02: Novel Linearly-Filled Derenzo PET Phantom Design

DOE Office of Scientific and Technical Information (OSTI.GOV)

Graves, S; Cox, B; Valdovinos, H

Purpose: To design a linearly-filled Derenzo positron emission tomography (PET) phantom, eliminating the extraneous radioisotope volumes in a conventional reservoir-type design. This activity reduction combined with the elimination of bubbles in smaller phantom channels would significantly reduce personnel dose, radioisotope cost, and would improve image quality by reducing out-of-slice activity scatter. Methods: A computer-aided design (CAD) was created of a modular Derenzo phantom consisting of three phantom layers with gaskets between the layers. The central piece contains the active pattern volume and channels connecting adjacent rods in a serpentine pattern. The two end-pieces contained an inlet and an outlet formore » filling purposes. Phantom prototypes were 3D printed on a Viper Si2 stereolithography machine. The two gaskets were fabricated from silicon sheets using a PLS 6.75 laser cutter. Phantoms were held together by pass-through glass-filled nylon bolts and nuts. Phantoms were filled with {sup 52}Mn, {sup 64}Cu, {sup 74}Br, and {sup 124}I for testing, and were imaged on a Siemens Inveon MicroPET scanner. Results: Four phantom prototypes were constructed using male Leur Lock fittings for inlet/outlet ports. 3D printed layers were sanded to ensure proper coupling to the silicon gaskets. The filling volume for each prototype was approximately 2.4 mL. The filling process was found to be rapid, leak-tight, and with minimal back-pressure. PET images were reconstructed by OSEM3D, and axial slices along the phantom pattern length were averaged to provide final images. Image distortion was isotope dependent with {sup 52}Mn and {sup 64}Cu having the least distortion and {sup 124}I having the most distortion. Conclusion: These results indicate that the linearlyfilled Derenzo design improves on conventional reservoir-type designs by eliminating potential bubbles in small channels and by reducing activity level, radioisotope volume, radioisotope cost, personnel dose, filling time, and out-of-slice activity scatter The method described in this abstract has been filed as a patent application to the US Patent and Trade Office by the Wisconsin Alumni Research Foundation (WARF).« less

Floating air riding seal for a turbine

DOEpatents

Ebert, Todd A

2016-08-16

A floating air riding seal for a gas turbine engine with a rotor and a stator, an annular piston chamber with an axial moveable annular piston assembly within the annular piston chamber formed in the stator, an annular cavity formed on the annular piston assembly that faces a seal surface on the rotor, where the axial moveable annular piston includes an inlet scoop on a side opposite to the annular cavity that scoops up the swirling cooling air and directs the cooling air to the annular cavity to form an air cushion with the seal surface of the rotor.

Characterization of a phantom setup for breast conserving cancer surgery

NASA Astrophysics Data System (ADS)

Chadwell, Jacob T.; Conley, Rebekah H.; Collins, Jarrod A.; Meszoely, Ingrid M.; Miga, Michael I.

2016-03-01

The purpose of this work is to develop an anatomically and mechanically representative breast phantom for the validation of breast conserving surgical therapies, specifically, in this case, image guided surgeries. Using three patients scheduled for lumpectomy and four healthy volunteers in mock surgical presentations, the magnitude, direction, and location of breast deformations was analyzed. A phantom setup was then designed to approximate such deformations in a mock surgical environment. Specifically, commercially available and custom-built polyvinyl alcohol (PVA) phantoms were used to mimic breast tissue during surgery. A custom designed deformation apparatus was then created to reproduce deformations seen in typical clinical setups of the pre- and intra-operative breast geometry. Quantitative analysis of the human subjects yielded a positive correlation between breast volume and amount of breast deformation. Phantom results reflected similar behavior with the custom-built PVA phantom outperforming the commercial phantom.

Testing the quality of images for permanent magnet desktop MRI systems using specially designed phantoms.

PubMed

Qiu, Jianfeng; Wang, Guozhu; Min, Jiao; Wang, Xiaoyan; Wang, Pengcheng

2013-12-21

Our aim was to measure the performance of desktop magnetic resonance imaging (MRI) systems using specially designed phantoms, by testing imaging parameters and analysing the imaging quality. We designed multifunction phantoms with diameters of 18 and 60 mm for desktop MRI scanners in accordance with the American Association of Physicists in Medicine (AAPM) report no. 28. We scanned the phantoms with three permanent magnet 0.5 T desktop MRI systems, measured the MRI image parameters, and analysed imaging quality by comparing the data with the AAPM criteria and Chinese national standards. Image parameters included: resonance frequency, high contrast spatial resolution, low contrast object detectability, slice thickness, geometrical distortion, signal-to-noise ratio (SNR), and image uniformity. The image parameters of three desktop MRI machines could be measured using our specially designed phantoms, and most parameters were in line with MRI quality control criterion, including: resonance frequency, high contrast spatial resolution, low contrast object detectability, slice thickness, geometrical distortion, image uniformity and slice position accuracy. However, SNR was significantly lower than in some references. The imaging test and quality control are necessary for desktop MRI systems, and should be performed with the applicable phantom and corresponding standards.

Evaluation of the novel algorithm of flexible ligand docking with moveable target-protein atoms.

PubMed

Sulimov, Alexey V; Zheltkov, Dmitry A; Oferkin, Igor V; Kutov, Danil C; Katkova, Ekaterina V; Tyrtyshnikov, Eugene E; Sulimov, Vladimir B

2017-01-01

We present the novel docking algorithm based on the Tensor Train decomposition and the TT-Cross global optimization. The algorithm is applied to the docking problem with flexible ligand and moveable protein atoms. The energy of the protein-ligand complex is calculated in the frame of the MMFF94 force field in vacuum. The grid of precalculated energy potentials of probe ligand atoms in the field of the target protein atoms is not used. The energy of the protein-ligand complex for any given configuration is computed directly with the MMFF94 force field without any fitting parameters. The conformation space of the system coordinates is formed by translations and rotations of the ligand as a whole, by the ligand torsions and also by Cartesian coordinates of the selected target protein atoms. Mobility of protein and ligand atoms is taken into account in the docking process simultaneously and equally. The algorithm is realized in the novel parallel docking SOL-P program and results of its performance for a set of 30 protein-ligand complexes are presented. Dependence of the docking positioning accuracy is investigated as a function of parameters of the docking algorithm and the number of protein moveable atoms. It is shown that mobility of the protein atoms improves docking positioning accuracy. The SOL-P program is able to perform docking of a flexible ligand into the active site of the target protein with several dozens of protein moveable atoms: the native crystallized ligand pose is correctly found as the global energy minimum in the search space with 157 dimensions using 4700 CPU ∗ h at the Lomonosov supercomputer.

Development of an organ-specific insert phantom generated using a 3D printer for investigations of cardiac computed tomography protocols.

PubMed

Abdullah, Kamarul A; McEntee, Mark F; Reed, Warren; Kench, Peter L

2018-04-30

An ideal organ-specific insert phantom should be able to simulate the anatomical features with appropriate appearances in the resultant computed tomography (CT) images. This study investigated a 3D printing technology to develop a novel and cost-effective cardiac insert phantom derived from volumetric CT image datasets of anthropomorphic chest phantom. Cardiac insert volumes were segmented from CT image datasets, derived from an anthropomorphic chest phantom of Lungman N-01 (Kyoto Kagaku, Japan). These segmented datasets were converted to a virtual 3D-isosurface of heart-shaped shell, while two other removable inserts were included using computer-aided design (CAD) software program. This newly designed cardiac insert phantom was later printed by using a fused deposition modelling (FDM) process via a Creatbot DM Plus 3D printer. Then, several selected filling materials, such as contrast media, oil, water and jelly, were loaded into designated spaces in the 3D-printed phantom. The 3D-printed cardiac insert phantom was positioned within the anthropomorphic chest phantom and 30 repeated CT acquisitions performed using a multi-detector scanner at 120-kVp tube potential. Attenuation (Hounsfield Unit, HU) values were measured and compared to the image datasets of real-patient and Catphan ® 500 phantom. The output of the 3D-printed cardiac insert phantom was a solid acrylic plastic material, which was strong, light in weight and cost-effective. HU values of the filling materials were comparable to the image datasets of real-patient and Catphan ® 500 phantom. A novel and cost-effective cardiac insert phantom for anthropomorphic chest phantom was developed using volumetric CT image datasets with a 3D printer. Hence, this suggested the printing methodology could be applied to generate other phantoms for CT imaging studies. © 2018 The Authors. Journal of Medical Radiation Sciences published by John Wiley & Sons Australia, Ltd on behalf of Australian Society of Medical Imaging and Radiation Therapy and New Zealand Institute of Medical Radiation Technology.

[Development of a software for 3D virtual phantom design].

PubMed

Zou, Lian; Xie, Zhao; Wu, Qi

2014-02-01

In this paper, we present a 3D virtual phantom design software, which was developed based on object-oriented programming methodology and dedicated to medical physics research. This software was named Magical Phan tom (MPhantom), which is composed of 3D visual builder module and virtual CT scanner. The users can conveniently construct any complex 3D phantom, and then export the phantom as DICOM 3.0 CT images. MPhantom is a user-friendly and powerful software for 3D phantom configuration, and has passed the real scene's application test. MPhantom will accelerate the Monte Carlo simulation for dose calculation in radiation therapy and X ray imaging reconstruction algorithm research.

Comparison of different phantoms used in digital diagnostic imaging

NASA Astrophysics Data System (ADS)

Bor, Dogan; Unal, Elif; Uslu, Anil

2015-09-01

The organs of extremity, chest, skull and lumbar were physically simulated using uniform PMMA slabs with different thicknesses alone and using these slabs together with aluminum plates and air gaps (ANSI Phantoms). The variation of entrance surface air kerma and scatter fraction with X-ray beam qualities was investigated for these phantoms and the results were compared with those measured from anthropomorphic phantoms. A flat panel digital radiographic system was used for all the experiments. Considerable variations of entrance surface air kermas were found for the same organs of different designs, and highest doses were measured for the PMMA slabs. A low contrast test tool and a contrast detail test object (CDRAD) were used together with each organ simulation of PMMA slabs and ANSI phantoms in order to test the clinical image qualities. Digital images of these phantom combinations and anthropomorphic phantoms were acquired in raw and clinically processed formats. Variation of image quality with kVp and post processing was evaluated using the numerical metrics of these test tools and measured contrast values from the anthropomorphic phantoms. Our results indicated that design of some phantoms may not be efficient enough to reveal the expected performance of the post processing algorithms.

A Novel Simple Phantom for Verifying the Dose of Radiation Therapy

PubMed Central

Lee, J. H.; Chang, L. T.; Shiau, A. C.; Chen, C. W.; Liao, Y. J.; Li, W. J.; Lee, M. S.; Hsu, S. M.

2015-01-01

A standard protocol of dosimetric measurements is used by the organizations responsible for verifying that the doses delivered in radiation-therapy institutions are within authorized limits. This study evaluated a self-designed simple auditing phantom for use in verifying the dose of radiation therapy; the phantom design, dose audit system, and clinical tests are described. Thermoluminescent dosimeters (TLDs) were used as postal dosimeters, and mailable phantoms were produced for use in postal audits. Correction factors are important for converting TLD readout values from phantoms into the absorbed dose in water. The phantom scatter correction factor was used to quantify the difference in the scattered dose between a solid water phantom and homemade phantoms; its value ranged from 1.084 to 1.031. The energy-dependence correction factor was used to compare the TLD readout of the unit dose irradiated by audit beam energies with 60Co in the solid water phantom; its value was 0.99 to 1.01. The setup-condition factor was used to correct for differences in dose-output calibration conditions. Clinical tests of the device calibrating the dose output revealed that the dose deviation was within 3%. Therefore, our homemade phantoms and dosimetric system can be applied for accurately verifying the doses applied in radiation-therapy institutions. PMID:25883980

A phantom design and assessment of lesion detectability in PET imaging

NASA Astrophysics Data System (ADS)

Wollenweber, Scott D.; Kinahan, Paul E.; Alessio, Adam M.

2017-03-01

The early detection of abnormal regions with increased tracer uptake in positron emission tomography (PET) is a key driver of imaging system design and optimization as well as choice of imaging protocols. Detectability, however, remains difficult to assess due to the need for realistic objects mimicking the clinical scene, multiple lesion-present and lesion-absent images and multiple observers. Fillable phantoms, with tradeoffs between complexity and utility, provide a means to quantitatively test and compare imaging systems under truth-known conditions. These phantoms, however, often focus on quantification rather than detectability. This work presents extensions to a novel phantom design and analysis techniques to evaluate detectability in the context of realistic, non-piecewise constant backgrounds. The design consists of a phantom filled with small solid plastic balls and a radionuclide solution to mimic heterogeneous background uptake. A set of 3D-printed regular dodecahedral `features' were included at user-defined locations within the phantom to create `holes' within the matrix of chaotically-packed balls. These features fill at approximately 3:1 contrast to the lumpy background. A series of signal-known-present (SP) and signal-known-absent (SA) sub-images were generated and used as input for observer studies. This design was imaged in a head-like 20 cm diameter, 20 cm long cylinder and in a body-like 36 cm wide by 21 cm tall by 40 cm long tank. A series of model observer detectability indices were compared across scan conditions (count levels, number of scan replicates), PET image reconstruction methods (with/without TOF and PSF) and between PET/CT scanner system designs using the same phantom imaged on multiple systems. The detectability index was further compared to the noise-equivalent count (NEC) level to characterize the relationship between NEC and observer SNR.

Low noise wing slat system with rigid cove-filled slat

NASA Technical Reports Server (NTRS)

Shmilovich, Arvin (Inventor); Yadlin, Yoram (Inventor)

2013-01-01

Concepts and technologies described herein provide for a low noise aircraft wing slat system. According to one aspect of the disclosure provided herein, a cove-filled wing slat is used in conjunction with a moveable panel rotatably attached to the wing slat to provide a high lift system. The moveable panel rotates upward against the rear surface of the slat during deployment of the slat, and rotates downward to bridge a gap width between the stowed slat and the lower wing surface, completing the continuous outer mold line shape of the wing, when the cove-filled slat is retracted to the stowed position.

Very compact, high-stability electrostatic actuator featuring contact-free self-limiting displacement

DOEpatents

Rodgers, M. Steven; Miller, Samuel L.

2003-01-01

A compact electrostatic actuator is disclosed for microelectromechanical (MEM) applications. The actuator utilizes stationary and moveable electrodes, with the stationary electrodes being formed on a substrate and the moveable electrodes being supported above the substrate on a frame. The frame provides a rigid structure which allows the electrostatic actuator to be operated at high voltages (up to 190 Volts) to provide a relatively large actuation force compared to conventional electrostatic comb actuators which are much larger in size. For operation at its maximum displacement, the electrostatic actuator is relatively insensitive to the exact value of the applied voltage and provides a self-limiting displacement.

Design and experimental evaluation of a high temperature radial turbine with a moveable sidewall nozzle

NASA Technical Reports Server (NTRS)

Rogo, Casimir; Roelke, Richard J.

1987-01-01

The uncooled, 2.27 kg/sec mass flow radial turbine designed to operate at 1477 K in the gas generator of an advanced, variable-capacity 683 kW turboshaft engine was configured with a cooled, movable sidewall nozzle capable of changing the stage flow capacity from 50 to 100 percent of maximum. Overall performance test data were obtained in a turbine test rig that duplicated engine Reynolds numbers; attention is given to the changing of flow capacity by moving the hub or shroud sidewall, vane sidewall leakage, vaneless space sidewall geometry, and nozzle-cooling injection. Data are presented in the form of turbine flow, efficiency, work parameter, and performance mappings.

The subresolution DaTSCAN phantom: a cost-effective, flexible alternative to traditional phantom technology.

PubMed

Taylor, Jonathan C; Vennart, Nicholas; Negus, Ian; Holmes, Robin; Bandmann, Oliver; Lo, Christine; Fenner, John

2018-03-01

The Alderson striatal phantom is frequently used to assess I-FP-CIT (Ioflupane) image quality and to test semi-quantification software. However, its design is associated with a number of limitations, in particular: unrealistic image appearances and inflexibility. A new physical phantom approach is proposed on the basis of subresolution phantom technology. The design incorporates thin slabs of attenuating material generated through additive manufacturing, and paper sheets with radioactive ink patterns printed on their surface, created with a conventional inkjet printer. The paper sheets and attenuating slabs are interleaved before scanning. Use of thin layers ensures that they cannot be individually resolved on reconstructed images. An investigation was carried out to demonstrate the performance of such a phantom in producing simplified I-FP-CIT uptake patterns. Single photon emission computed tomography imaging was carried out on an assembled phantom designed to mimic a healthy patient. Striatal binding ratio results and linear striatal dimensions were calculated from the reconstructed data and compared with that of 22 clinical patients without evidence of Parkinsonian syndrome, determined from clinical follow-up. Striatal binding ratio results for the fully assembled phantom were: 3.1, 3.3, 2.9 and 2.6 for the right caudate, left caudate, right putamen and right caudate, respectively. All were within two SDs of results derived from a cohort of clinical patients. Medial-lateral and anterior-posterior dimensions of the simulated striata were also within the range of values seen in clinical data. This work provides the foundation for the generation of a range of more clinically realistic, physical phantoms.

Development of a universal medical X-ray imaging phantom prototype.

PubMed

Groenewald, Annemari; Groenewald, Willem A

2016-11-08

Diagnostic X-ray imaging depends on the maintenance of image quality that allows for proper diagnosis of medical conditions. Maintenance of image quality requires quality assurance programs on the various X-ray modalities, which consist of pro-jection radiography (including mobile X-ray units), fluoroscopy, mammography, and computed tomography (CT) scanning. Currently a variety of modality-specific phantoms are used to perform quality assurance (QA) tests. These phantoms are not only expensive, but suitably trained personnel are needed to successfully use them and interpret the results. The question arose as to whether a single universal phantom could be designed and applied to all of the X-ray imaging modalities. A universal phantom would reduce initial procurement cost, possibly reduce the time spent on QA procedures and simplify training of staff on the single device. The aim of the study was to design and manufacture a prototype of a universal phantom, suitable for image quality assurance in general X-rays, fluoroscopy, mammography, and CT scanning. The universal phantom should be easy to use and would enable automatic data analysis, pass/fail reporting, and corrective action recommendation. In addition, a universal phantom would especially be of value in low-income countries where finances and human resources are limited. The design process included a thorough investigation of commercially available phantoms. Image quality parameters necessary for image quality assurance in the different X-ray imaging modalities were determined. Based on information obtained from the above-mentioned investigations, a prototype of a universal phantom was developed, keeping ease of use and reduced cost in mind. A variety of possible phantom housing and insert materials were investigated, considering physical properties, machinability, and cost. A three-dimensional computer model of the first phantom prototype was used to manufacture the prototype housing and inserts. Some of the inserts were 3D-printed, others were machined from different materials. The different components were assembled to form the first prototype of the universal X-ray imaging phantom. The resulting prototype of the universal phantom conformed to the aims of a single phantom for multiple imag-ing modalities, which would be easy to use and manufacture at a reduced cost. A PCT International Patent Application No. PCT/IB2016/051165 has been filed for this technology. © 2016 The Authors.

Quantum noise properties of CT images with anatomical textured backgrounds across reconstruction algorithms: FBP and SAFIRE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Solomon, Justin, E-mail: justin.solomon@duke.edu; Samei, Ehsan

2014-09-15

Purpose: Quantum noise properties of CT images are generally assessed using simple geometric phantoms with uniform backgrounds. Such phantoms may be inadequate when assessing nonlinear reconstruction or postprocessing algorithms. The purpose of this study was to design anatomically informed textured phantoms and use the phantoms to assess quantum noise properties across two clinically available reconstruction algorithms, filtered back projection (FBP) and sinogram affirmed iterative reconstruction (SAFIRE). Methods: Two phantoms were designed to represent lung and soft-tissue textures. The lung phantom included intricate vessel-like structures along with embedded nodules (spherical, lobulated, and spiculated). The soft tissue phantom was designed based onmore » a three-dimensional clustered lumpy background with included low-contrast lesions (spherical and anthropomorphic). The phantoms were built using rapid prototyping (3D printing) technology and, along with a uniform phantom of similar size, were imaged on a Siemens SOMATOM Definition Flash CT scanner and reconstructed with FBP and SAFIRE. Fifty repeated acquisitions were acquired for each background type and noise was assessed by estimating pixel-value statistics, such as standard deviation (i.e., noise magnitude), autocorrelation, and noise power spectrum. Noise stationarity was also assessed by examining the spatial distribution of noise magnitude. The noise properties were compared across background types and between the two reconstruction algorithms. Results: In FBP and SAFIRE images, noise was globally nonstationary for all phantoms. In FBP images of all phantoms, and in SAFIRE images of the uniform phantom, noise appeared to be locally stationary (within a reasonably small region of interest). Noise was locally nonstationary in SAFIRE images of the textured phantoms with edge pixels showing higher noise magnitude compared to pixels in more homogenous regions. For pixels in uniform regions, noise magnitude was reduced by an average of 60% in SAFIRE images compared to FBP. However, for edge pixels, noise magnitude ranged from 20% higher to 40% lower in SAFIRE images compared to FBP. SAFIRE images of the lung phantom exhibited distinct regions with varying noise texture (i.e., noise autocorrelation/power spectra). Conclusions: Quantum noise properties observed in uniform phantoms may not be representative of those in actual patients for nonlinear reconstruction algorithms. Anatomical texture should be considered when evaluating the performance of CT systems that use such nonlinear algorithms.« less

Measuring radiation dose in computed tomography using elliptic phantom and free-in-air, and evaluating iterative metal artifact reduction algorithm

NASA Astrophysics Data System (ADS)

Morgan, Ashraf

The need for an accurate and reliable way for measuring patient dose in multi-row detector computed tomography (MDCT) has increased significantly. This research was focusing on the possibility of measuring CT dose in air to estimate Computed Tomography Dose Index (CTDI) for routine quality control purposes. New elliptic CTDI phantom that better represent human geometry was manufactured for investigating the effect of the subject shape on measured CTDI. Monte Carlo simulation was utilized in order to determine the dose distribution in comparison to the traditional cylindrical CTDI phantom. This research also investigated the effect of Siemens health care newly developed iMAR (iterative metal artifact reduction) algorithm, arthroplasty phantom was designed and manufactured that purpose. The design of new phantoms was part of the research as they mimic the human geometry more than the existing CTDI phantom. The standard CTDI phantom is a right cylinder that does not adequately represent the geometry of the majority of the patient population. Any dose reduction algorithm that is used during patient scan will not be utilized when scanning the CTDI phantom, so a better-designed phantom will allow the use of dose reduction algorithms when measuring dose, which leads to better dose estimation and/or better understanding of dose delivery. Doses from a standard CTDI phantom and the newly-designed phantoms were compared to doses measured in air. Iterative reconstruction is a promising technique in MDCT dose reduction and artifacts correction. Iterative reconstruction algorithms have been developed to address specific imaging tasks as is the case with Iterative Metal Artifact Reduction or iMAR which was developed by Siemens and is to be in use with the companys future computed tomography platform. The goal of iMAR is to reduce metal artifact when imaging patients with metal implants and recover CT number of tissues adjacent to the implant. This research evaluated iMAR capability of recovering CT numbers and reducing noise. Also, the use of iMAR should allow using lower tube voltage instead of 140 KVp which is used frequently to image patients with shoulder implants. The evaluations of image quality and dose reduction were carried out using an arthroplasty phantom.

NOTE: An innovative phantom for quantitative and qualitative investigation of advanced x-ray imaging technologies

NASA Astrophysics Data System (ADS)

Chiarot, C. B.; Siewerdsen, J. H.; Haycocks, T.; Moseley, D. J.; Jaffray, D. A.

2005-11-01

Development, characterization, and quality assurance of advanced x-ray imaging technologies require phantoms that are quantitative and well suited to such modalities. This note reports on the design, construction, and use of an innovative phantom developed for advanced imaging technologies (e.g., multi-detector CT and the numerous applications of flat-panel detectors in dual-energy imaging, tomosynthesis, and cone-beam CT) in diagnostic and image-guided procedures. The design addresses shortcomings of existing phantoms by incorporating criteria satisfied by no other single phantom: (1) inserts are fully 3D—spherically symmetric rather than cylindrical; (2) modules are quantitative, presenting objects of known size and contrast for quality assurance and image quality investigation; (3) features are incorporated in ideal and semi-realistic (anthropomorphic) contexts; and (4) the phantom allows devices to be inserted and manipulated in an accessible module (right lung). The phantom consists of five primary modules: (1) head, featuring contrast-detail spheres approximate to brain lesions; (2) left lung, featuring contrast-detail spheres approximate to lung modules; (3) right lung, an accessible hull in which devices may be placed and manipulated; (4) liver, featuring conrast-detail spheres approximate to metastases; and (5) abdomen/pelvis, featuring simulated kidneys, colon, rectum, bladder, and prostate. The phantom represents a two-fold evolution in design philosophy—from 2D (cylindrically symmetric) to fully 3D, and from exclusively qualitative or quantitative to a design accommodating quantitative study within an anatomical context. It has proven a valuable tool in investigations throughout our institution, including low-dose CT, dual-energy radiography, and cone-beam CT for image-guided radiation therapy and surgery.

Design of a tracked ultrasound calibration phantom made of LEGO bricks

NASA Astrophysics Data System (ADS)

Walsh, Ryan; Soehl, Marie; Rankin, Adam; Lasso, Andras; Fichtinger, Gabor

2014-03-01

PURPOSE: Spatial calibration of tracked ultrasound systems is commonly performed using precisely fabricated phantoms. Machining or 3D printing has relatively high cost and not easily available. Moreover, the possibilities for modifying the phantoms are very limited. Our goal was to find a method to construct a calibration phantom from affordable, widely available components, which can be built in short time, can be easily modified, and provides comparable accuracy to the existing solutions. METHODS: We designed an N-wire calibration phantom made of LEGO® bricks. To affirm the phantom's reproducibility and build time, ten builds were done by first-time users. The phantoms were used for a tracked ultrasound calibration by an experienced user. The success of each user's build was determined by the lowest root mean square (RMS) wire reprojection error of three calibrations. The accuracy and variance of calibrations were evaluated for the calibrations produced for various tracked ultrasound probes. The proposed model was compared to two of the currently available phantom models for both electromagnetic and optical tracking. RESULTS: The phantom was successfully built by all ten first-time users in an average time of 18.8 minutes. It cost approximately $10 CAD for the required LEGO® bricks and averaged a 0.69mm of error in the calibration reproducibility for ultrasound calibrations. It is one third the cost of similar 3D printed phantoms and takes much less time to build. The proposed phantom's image reprojections were 0.13mm more erroneous than those of the highest performing current phantom model The average standard deviation of multiple 3D image reprojections differed by 0.05mm between the phantoms CONCLUSION: It was found that the phantom could be built in less time, was one third the cost, compared to similar 3D printed models. The proposed phantom was found to be capable of producing equivalent calibrations to 3D printed phantoms.

A novel composite material specifically developed for ultrasound bone phantoms: cortical, trabecular and skull

NASA Astrophysics Data System (ADS)

Wydra, A.; Maev, R. Gr

2013-11-01

In the various stages of developing diagnostic and therapeutic equipment, the use of phantoms can play a very important role in improving the process, help in implementation, testing and calibrations. Phantoms are especially useful in developing new applications and training new doctors in medical schools. However, devices that use different physical factors, such as MRI, Ultrasound, CT Scan, etc will require the phantom to be made of different physical properties. In this paper we introduce the properties of recently designed new materials for developing phantoms for ultrasonic human body investigation, which in today's market make up more than 30% in the world of phantoms. We developed a novel composite material which allows fabrication of various kinds of ultrasound bone phantoms to mimic most of the acoustical properties of human bones. In contrast to the ex vivo tissues, the proposed material can maintain the physical and acoustical properties unchanged for long periods of time; moreover, these properties can be custom designed and created to suit specific needs. As a result, we introduce three examples of ultrasound phantoms that we manufactured in our laboratory: cortical, trabecular and skull bone phantoms. The paper also presents the results of a comparison study between the acoustical and physical properties of actual human bones (reported in the referenced literatures) and the phantoms manufactured by us.

A novel composite material specifically developed for ultrasound bone phantoms: cortical, trabecular and skull.

PubMed

Wydra, A; Maev, R Gr

2013-11-21

In the various stages of developing diagnostic and therapeutic equipment, the use of phantoms can play a very important role in improving the process, help in implementation, testing and calibrations. Phantoms are especially useful in developing new applications and training new doctors in medical schools. However, devices that use different physical factors, such as MRI, Ultrasound, CT Scan, etc will require the phantom to be made of different physical properties. In this paper we introduce the properties of recently designed new materials for developing phantoms for ultrasonic human body investigation, which in today's market make up more than 30% in the world of phantoms. We developed a novel composite material which allows fabrication of various kinds of ultrasound bone phantoms to mimic most of the acoustical properties of human bones. In contrast to the ex vivo tissues, the proposed material can maintain the physical and acoustical properties unchanged for long periods of time; moreover, these properties can be custom designed and created to suit specific needs. As a result, we introduce three examples of ultrasound phantoms that we manufactured in our laboratory: cortical, trabecular and skull bone phantoms. The paper also presents the results of a comparison study between the acoustical and physical properties of actual human bones (reported in the referenced literatures) and the phantoms manufactured by us.

SU-C-209-07: Phantoms for Digital Breast Tomosynthesis Imaging System Evaluation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jacobson, D; Liu, Y

2016-06-15

Purpose: Digital Breast Tomosynthesis (DBT) is gaining importance in breast imaging. There is a need for phantoms that can be used for image evaluation and comparison. Existing commercially available phantoms for DBT are expensive and may lack clinically relevant test objects. The purpose of this study is to develop phantoms for DBT evaluation. Methods Four phantoms have been designed and constructed to assess the image quality (IQ) of two DBT systems. The first contains a spiral of 0.3 mm SiC beads in gelatin to measure the tomographic slice thickness profile and uniformity of coverage in a series of tomographic planes.more » The second contains simulated tumors inclined with respect to the phantom base to assess tomographic image quality. The third has a tilted array of discs with varying contrast and diameter. This phantom was imaged alone and in a stack of TE slabs giving 2 to 10 cm thickness. The fourth has a dual wedge of glandular and adipose simulating materials. One wedge contains discs with varying diameter and thickness; the other supports a mass with six simulated spicules of varying size and a cluster of simulated calcifications. The simulated glandular tissue material varies between 35 and 100% of the total thickness (5.5 cm). Results: All phantoms were scanned successfully. The best IQ comparison was achieved with the dual wedge phantom as demonstrated by the spiculated mass and calcifications. Images were evaluated by two radiologists and one physicist. The projection images and corresponding set of tomographic planes were comparable and the synthesized projection images were inferior to the projection images for both systems. Conclusion: Four phantoms were designed, constructed and imaged on two DBT systems. They successfully demonstrated performance differences between two systems, and between true and synthesized projection images. Future work will incorporate these designs into a single phantom.« less

Framework for quantitative evaluation of 3D vessel segmentation approaches using vascular phantoms in conjunction with 3D landmark localization and registration

NASA Astrophysics Data System (ADS)

Wörz, Stefan; Hoegen, Philipp; Liao, Wei; Müller-Eschner, Matthias; Kauczor, Hans-Ulrich; von Tengg-Kobligk, Hendrik; Rohr, Karl

2016-03-01

We introduce a framework for quantitative evaluation of 3D vessel segmentation approaches using vascular phantoms. Phantoms are designed using a CAD system and created with a 3D printer, and comprise realistic shapes including branches and pathologies such as abdominal aortic aneurysms (AAA). To transfer ground truth information to the 3D image coordinate system, we use a landmark-based registration scheme utilizing fiducial markers integrated in the phantom design. For accurate 3D localization of the markers we developed a novel 3D parametric intensity model that is directly fitted to the markers in the images. We also performed a quantitative evaluation of different vessel segmentation approaches for a phantom of an AAA.

Design and characterization of a phantom that simultaneously simulates tissue optical properties between 400 and 650 nm

NASA Astrophysics Data System (ADS)

Wagnieres, Georges A.; Cheng, Shangguan; Zellweger, Matthieu; Doegnitz-Utke, Nora; Braichotte, Daniel; Ballini, Jean-Pierre; van den Bergh, Hubert

1996-12-01

The design and characterization of optical phantoms which have the same absorption and scattering characteristics as biological tissues in a broad spectral window (between 400 and 650 nm) are presented. These low cost phantoms use agarose dissolved in water as the transparent matrix. The latter is loaded with various amounts of silicon dioxide, intralipid, ink, bovine serum, blood, azide, penicillin and fluorochromes. The silicon dioxide and intralipid particles are responsible for the light scattering whereas the ink and blood are the absorbers. The penicillin and the azide are used to insure the conservation of such phantoms when stored at 4 degrees Celsius. The serum and fluorochromes, such as Coumarin 30, produce an autofluorescence similar to human tissues. Various fluorochromes or photosensitizers can be added to these phantoms to simulate a photodetection procedure. The absorption and fluorescence spectroscopy of the dyes tested was not different in these phantoms than in live tissues. The mechanical properties of these gelatinous phantoms are also of interest as they can easily be molded and reshaped with a conventional cutter, so that for instance layered structures, with different optical properties in each layer, can be designed. The optical properties of these phantoms were determined between 400 and 650 nm by measuring their effective attenuation coefficient ((mu) eff) and total reflectance (Rd). The microscopic absorption and reduced scattering coefficients ((mu) a, (mu) s') were deduced from (mu) eff and Rd using a Monte-Carlo simulation.

Development and clinical application of a length-adjustable water phantom for total body irradiation.

PubMed

Chen, Zhi-Wei; Yao, Sheng-Yu; Zhang, Tie-Ning; Zhu, Zhen-Hua; Hu, Zhe-Kai; Lu, Xun

2012-08-01

A new type of water phantom which would be specialised for the absorbed dose measurement in total body irradiation (TBI) treatment is developed. Ten millimetres of thick Plexiglas plates were arranged to form a square cube with 300 mm of edge length. An appropriate sleeve-type piston was installed on the side wall, and a tabular Plexiglas piston was positioned inside the sleeve. By pushing and pulling the piston, the length of the self-made water phantom could be varied to meet the required patients' physical sizes. To compare the international standard water phantom with the length-adjustable and the Plexiglas phantoms, absorbed dose for 6-MV X ray was measured by an ionisation chamber at different depths in three kinds of phantoms. In 70 cases with TBI, midplane doses were metered using the length-adjustable and the Plexiglas phantoms for simulating human dimensions, and dose validation was synchronously carried out. There were no significant statistical differences, p > 0.05, through statistical processing of data from the international standard water phantom and the self-designed one. There were significant statistical differences, p < 0.05, between the two sets of data from the standard and the Plexiglas one. In addition, the absolute difference had a positive correlation with the varied depth of the detector in the Plexiglas phantom. Comparing the data of clinical treatment, the differences were all <1 % among the prescription doses and the validation data collected from the self-design water phantom. However, the differences collected from the Plexiglas phantom were increasing gradually from +0.77 to +2.30 % along with increasing body width. Obviously, the difference had a positive correlation with the body width. The results proved that the new length-adjustable water phantom is more accurate for simulating human dimensions than Plexiglas phantom.

Use of maxillofacial laboratory materials to construct a tissue-equivalent head phantom with removable titanium implantable devices for use in verification of the dose of intensity-modulated radiotherapy.

PubMed

Morris, K

2017-06-01

The dose of radiotherapy is often verified by measuring the dose of radiation at specific points within a phantom. The presence of high-density implant materials such as titanium, however, may cause complications both during calculation and delivery of the dose. Numerous studies have reported photon/electron backscatter and alteration of the dose by high-density implants, but we know of no evidence of a dosimetry phantom that incorporates high density implants or fixtures. The aim of the study was to design and manufacture a tissue-equivalent head phantom for use in verification of the dose in radiotherapy using a combination of traditional laboratory materials and techniques and 3-dimensional technology that can incorporate titanium maxillofacial devices. Digital designs were used together with Mimics® 18.0 (Materialise NV) and FreeForm® software. DICOM data were downloaded and manipulated into the final pieces of the phantom mould. Three-dimensional digital objects were converted into STL files and exported for additional stereolithography. Phantoms were constructed in four stages: material testing and selection, design of a 3-dimensional mould, manufacture of implants, and final fabrication of the phantom using traditional laboratory techniques. Three tissue-equivalent materials were found and used to successfully manufacture a suitable phantom with interchangeable sections that contained three versions of titanium maxillofacial implants. Maxillofacial and other materials can be used to successfully construct a head phantom with interchangeable titanium implant sections for use in verification of doses of radiotherapy. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

Estimating organic maturity from well logs, Upper Cretaceous Austin Chalk, Texas Gulf coast

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hines, G.A.; Berg, R.R.

1990-09-01

The Austin Chalk is both a source rock for oil and a fractured reservoir, and the evaluation of its organic maturity from well logs could be an aid to exploration and production. Geochemical measurements have shown three zones of organic maturity for source materials: (1) an immature zone to depths of 6,000 ft, (2) a peak-generation and accumulation zone from 6,000 to 6,500 ft, and (3) a mature, expulsion and migration zone below 6,500 ft. The response of common well logs identifies these zones. True resistivity (R{sub t}) is low in the immature zone, increases to a maximum in themore » peak-generation zone, and decreases to intermediate values in the expulsion zone. Density and neutron porosities are different in the immature zone but are nearly equal in the peak generation and expulsion zones. Correlations with conventional core analyses indicate that R{sub t} values between 9 and 40 ohm-m in the expulsion zone reflect a moveable oil saturation of 10 to 20% in the rock matrix. The moveable saturation provides oil from the matrix to fractures and is essential for sustained oil production. Therefore, the evaluation of moveable oil from well logs could be important in exploration.« less

A physical breast phantom for 2D and 3D x-ray imaging made through inkjet printing

NASA Astrophysics Data System (ADS)

Ikejimba, Lynda C.; Graff, Christian G.; Rosenthal, Shani; Badal, Andreu; Ghammraoui, Bahaa; Lo, Joseph Y.; Glick, Stephen J.

2017-03-01

Physical breast phantoms are used for imaging evaluation studies with 2D and 3D breast x-ray systems, serving as surrogates for human patients. However, there is a presently a limited selection of available phantoms that are realistic, in terms of containing the complex tissue architecture of the human breast. In addition, not all phantoms can be successfully utilized for both 2D and 3D breast imaging. Additionally, many of the phantoms are uniform or unrealistic in appearance, expensive, or difficult to obtain. The purpose of this work was to develop a new method to generate realistic physical breast phantoms using easy to obtain and inexpensive materials. First, analytical modeling was used to design a virtual model, which was then compressed using finite element modeling. Next, the physical phantom was realized through inkjet printing with a standard inkjet printer using parchment paper and specialized inks, formulated using silver nanoparticles and a bismuth salt. The printed phantom sheets were then aligned and held together using a custom designed support plate made of PMMA, and imaged on clinical FFDM and DBT systems. Objects of interest were also placed within the phantom to simulate microcalcifications, pathologies that often occur in the breast. The linear attenuation coefficients of the inks and parchment were compared against tissue equivalent samples and found to be similar to breast tissue. The phantom is promising for use in imaging studies and developing QC protocols.

Optical phantoms with variable properties and geometries for diffuse and fluorescence optical spectroscopy

NASA Astrophysics Data System (ADS)

Leh, Barbara; Siebert, Rainer; Hamzeh, Hussein; Menard, Laurent; Duval, Marie-Alix; Charon, Yves; Abi Haidar, Darine

2012-10-01

Growing interest in optical instruments for biomedical applications has increased the use of optically calibrated phantoms. Often associated with tissue modeling, phantoms allow the characterization of optical devices for clinical purposes. Fluorescent gel phantoms have been developed, mimicking optical properties of healthy and tumorous brain tissues. Specific geometries of dedicated molds offer multiple-layer phantoms with variable thicknesses and monolayer phantoms with cylindrical inclusions at various depths and diameters. Organic chromophores are added to allow fluorescence spectroscopy. These phantoms are designed to be used with 405 nm as the excitation wavelength. This wavelength is then adapted to excite large endogenous molecules. The benefits of these phantoms in understanding fluorescence tissue analysis are then demonstrated. In particular, detectability aspects as a function of geometrical and optical parameters are presented and discussed.

Design and construction of prototype radio antenna for shortest radio wavelengths

NASA Technical Reports Server (NTRS)

Leighton, R. B.

1975-01-01

A paraboloid radio antenna of 10.4 meters diameter, 0.41 meter focal length was constructed and its successful completion is described. The surface accuracy of the antenna is at least four times better than any existing antenna in its class size (50 micrometers rms). Antenna design specifications (i.e., for mounting, drive motors, honeycomb structures) are discussed and engineering drawings and photographs of antenna components are shown. The antenna will be used for millimeter-wave interferometry and sub-millimeter wave radiometry over a full frequency range (up to approximately 860 GHz). The antenna will also be moveable (for interferometric use) between reinforced concrete pads by rail. The effects of the weather and gravity on antenna performance are briefly discussed.

Design of a head phantom produced on a 3D rapid prototyping printer and comparison with a RANDO and 3M lucite head phantom in eye dosimetry applications

NASA Astrophysics Data System (ADS)

Homolka, Peter; Figl, Michael; Wartak, Andreas; Glanzer, Mathias; Dünkelmeyer, Martina; Hojreh, Azadeh; Hummel, Johann

2017-04-01

An anthropomorphic head phantom including eye inserts allowing placement of TLDs 3 mm below the cornea has been produced on a 3D printer using a photo-cured acrylic resin to best allow tissue equivalence. Thus Hp(3) can be determined in radiological and interventional photon radiation fields. Eye doses and doses to the forehead have been compared to an Alderson RANDO head and a 3M Lucite skull phantom in terms of surface dose per incident air kerma for frontal irradiation since the commercial phantoms do not allow placement of TLDs 3 mm below the corneal surface. A comparison of dose reduction factors (DRFs) of a common lead glasses model has also been performed. Eye dose per incident air kerma were comparable between all three phantoms (printed phantom: 1.40, standard error (SE) 0.04; RANDO: 1.36, SE 0.03; 3M: 1.37, SE 0.03). Doses to the forehead were identical to eye surface doses for the printed phantom and the RANDO head (ratio 1.00 SE 0.04, and 0.99 SE 0.03, respectively). In the 3M Lucite skull phantom dose on the forehead was 15% lower than dose to the eyes attributable to phantom properties. DRF of a sport frame style leaded glasses model with 0.75 mm lead equivalence measured were 6.8 SE 0.5, 9.3 SE 0.4 and 10.5 SE 0.5 for the RANDO head, the printed phantom, and the 3M Lucite head phantom, respectively, for frontal irradiation. A comparison of doses measured in 3 mm depth and on the surface of the eyes in the printed phantom revealed no difference larger than standard errors from TLD dosimetry. 3D printing offers an interesting opportunity for phantom design with increasing potential as printers allowing combinations of tissue substitutes will become available. Variations between phantoms may provide a useful indication of uncertainty budgets when using phantom measurements to estimate individual personnel doses.

Design of a head phantom produced on a 3D rapid prototyping printer and comparison with a RANDO and 3M lucite head phantom in eye dosimetry applications.

PubMed

Homolka, Peter; Figl, Michael; Wartak, Andreas; Glanzer, Mathias; Dünkelmeyer, Martina; Hojreh, Azadeh; Hummel, Johann

2017-04-21

An anthropomorphic head phantom including eye inserts allowing placement of TLDs 3 mm below the cornea has been produced on a 3D printer using a photo-cured acrylic resin to best allow tissue equivalence. Thus H p (3) can be determined in radiological and interventional photon radiation fields. Eye doses and doses to the forehead have been compared to an Alderson RANDO head and a 3M Lucite skull phantom in terms of surface dose per incident air kerma for frontal irradiation since the commercial phantoms do not allow placement of TLDs 3 mm below the corneal surface. A comparison of dose reduction factors (DRFs) of a common lead glasses model has also been performed. Eye dose per incident air kerma were comparable between all three phantoms (printed phantom: 1.40, standard error (SE) 0.04; RANDO: 1.36, SE 0.03; 3M: 1.37, SE 0.03). Doses to the forehead were identical to eye surface doses for the printed phantom and the RANDO head (ratio 1.00 SE 0.04, and 0.99 SE 0.03, respectively). In the 3M Lucite skull phantom dose on the forehead was 15% lower than dose to the eyes attributable to phantom properties. DRF of a sport frame style leaded glasses model with 0.75 mm lead equivalence measured were 6.8 SE 0.5, 9.3 SE 0.4 and 10.5 SE 0.5 for the RANDO head, the printed phantom, and the 3M Lucite head phantom, respectively, for frontal irradiation. A comparison of doses measured in 3 mm depth and on the surface of the eyes in the printed phantom revealed no difference larger than standard errors from TLD dosimetry. 3D printing offers an interesting opportunity for phantom design with increasing potential as printers allowing combinations of tissue substitutes will become available. Variations between phantoms may provide a useful indication of uncertainty budgets when using phantom measurements to estimate individual personnel doses.

Locomotion of Amorphous Surface Robots

NASA Technical Reports Server (NTRS)

Bradley, Arthur T. (Inventor)

2018-01-01

An amorphous robot includes a compartmented bladder containing fluid, a valve assembly, and an outer layer encapsulating the bladder and valve assembly. The valve assembly draws fluid from a compartment(s) and discharges the drawn fluid into a designated compartment to displace the designated compartment with respect to the surface. Another embodiment includes elements each having a variable property, an outer layer that encapsulates the elements, and a control unit. The control unit energizes a designated element to change its variable property, thereby moving the designated element. The elements may be electromagnetic spheres with a variable polarity or shape memory polymers with changing shape and/or size. Yet another embodiment includes an elongated flexible tube filled with ferrofluid, a moveable electromagnet, an actuator, and a control unit. The control unit energizes the electromagnet and moves the electromagnet via the actuator to magnetize the ferrofluid and lengthen the flexible tube.

Locomotion of Amorphous Surface Robots

NASA Technical Reports Server (NTRS)

Bradley, Arthur T. (Inventor)

2016-01-01

An amorphous robot includes a compartmented bladder containing fluid, a valve assembly, and an outer layer encapsulating the bladder and valve assembly. The valve assembly draws fluid from a compartment(s) and discharges the drawn fluid into a designated compartment to displace the designated compartment with respect to the surface. Another embodiment includes elements each having a variable property, an outer layer that encapsulates the elements, and a control unit. The control unit energizes a designated element to change its variable property, thereby moving the designated element. The elements may be electromagnetic spheres with a variable polarity or shape memory polymers with changing shape and/or size. Yet another embodiment includes an elongated flexible tube filled with ferrofluid, a moveable electromagnet, an actuator, and a control unit. The control unit energizes the electromagnet and moves the electromagnet via the actuator to magnetize the ferrofluid and lengthen the flexible tube.

Locomotion of Amorphous Surface Robots

NASA Technical Reports Server (NTRS)

Bradley, Arthur T. (Inventor)

2014-01-01

An amorphous robot includes a compartmented bladder containing fluid, a valve assembly, and an outer layer encapsulating the bladder and valve assembly. The valve assembly draws fluid from a compartment(s) and discharges the drawn fluid into a designated compartment to displace the designated compartment with respect to the surface. Another embodiment includes elements each having a variable property, an outer layer that encapsulates the elements, and a control unit. The control unit energizes a designated element to change its variable property, thereby moving the designated element. The elements may be electromagnetic spheres with a variable polarity or shape memory polymers with changing shape and/or size. Yet another embodiment includes an elongated flexible tube filled with ferrofluid, a moveable electromagnet, an actuator, and a control unit. The control unit energizes the electromagnet and moves the electromagnet via the actuator to magnetize the ferrofluid and lengthen the flexible tube.

Organosilicon phantom for photoacoustic imaging

NASA Astrophysics Data System (ADS)

Avigo, Cinzia; Di Lascio, Nicole; Armanetti, Paolo; Kusmic, Claudia; Cavigli, Lucia; Ratto, Fulvio; Meucci, Sandro; Masciullo, Cecilia; Cecchini, Marco; Pini, Roberto; Faita, Francesco; Menichetti, Luca

2015-04-01

Photoacoustic imaging is an emerging technique. Although commercially available photoacoustic imaging systems currently exist, the technology is still in its infancy. Therefore, the design of stable phantoms is essential to achieve semiquantitative evaluation of the performance of a photoacoustic system and can help optimize the properties of contrast agents. We designed and developed a polydimethylsiloxane (PDMS) phantom with exceptionally fine geometry; the phantom was tested using photoacoustic experiments loaded with the standard indocyanine green dye and compared to an agar phantom pattern through polyethylene glycol-gold nanorods. The linearity of the photoacoustic signal with the nanoparticle number was assessed. The signal-to-noise ratio and contrast were employed as image quality parameters, and enhancements of up to 50 and up to 300%, respectively, were measured with the PDMS phantom with respect to the agar one. A tissue-mimicking (TM)-PDMS was prepared by adding TiO2 and India ink; photoacoustic tests were performed in order to compare the signal generated by the TM-PDMS and the biological tissue. The PDMS phantom can become a particularly promising tool in the field of photoacoustics for the evaluation of the performance of a PA system and as a model of the structure of vascularized soft tissues.

Application of the 4-D XCAT Phantoms in Biomedical Imaging and Beyond.

PubMed

Segars, W Paul; Tsui, B M W; Cai, Jing; Yin, Fang-Fang; Fung, George S K; Samei, Ehsan

2018-03-01

The four-dimensional (4-D) eXtended CArdiac-Torso (XCAT) series of phantoms was developed to provide accurate computerized models of the human anatomy and physiology. The XCAT series encompasses a vast population of phantoms of varying ages from newborn to adult, each including parameterized models for the cardiac and respiratory motions. With great flexibility in the XCAT's design, any number of body sizes, different anatomies, cardiac or respiratory motions or patterns, patient positions and orientations, and spatial resolutions can be simulated. As such, the XCAT phantoms are gaining a wide use in biomedical imaging research. There they can provide a virtual patient base from which to quantitatively evaluate and improve imaging instrumentation, data acquisition, techniques, and image reconstruction and processing methods which can lead to improved image quality and more accurate clinical diagnoses. The phantoms have also found great use in radiation dosimetry, radiation therapy, medical device design, and even the security and defense industry. This review paper highlights some specific areas in which the XCAT phantoms have found use within biomedical imaging and other fields. From these examples, we illustrate the increasingly important role that computerized phantoms and computer simulation are playing in the research community.

Daylighting and shuttering: RIB system mechanical design and preliminary performance data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kinney, L.; Reynolds, D.

1983-12-01

The Reflective, Insulating Blind (RIB) system is a flexible, user-controlled daylighting device which also has direct thermal advantages: it can reject a considerable portion of summer sun while still retaining an adequate daylighting function; and it functions as moveable insulation to significantly decrease thermal losses through fenestration during evening hours. The conceptual design of the RIB system was accomplished by Barnes and Shapira at the Oak Ridge National Laboratory (ORNL). Mechanical design and prototype fabrication was accomplished by the authors and 29 systems were installed immediately inside existing south-facing windows of an energy-efficient office and dormitory at ORNL. The buildingmore » is a heavily-instrumented, passively-solar-heated structure for which reliable performance data was gathered and analyzed before the addition of RIB systems, thus facilitating the interpretation of ''after RIB'' performance data.« less

The Advanced Light Source Elliptically Polarizing Undulator

NASA Astrophysics Data System (ADS)

Marks, Steve; Cortopassi, Christopher; Devries, Jan; Hoyer, Egon; Leinbach, Robert; Minamihara, Yoshi; Padmore, Howard; Pipersky, Paul; Plate, Dave; Schlueter, Ross; Young, Anthony

1997-05-01

An elliptically polarizing undulator for the Advanced Light Source has been designed and is currently under construction. The magnetic design is a four quadrant pure permanent magnet structure featuring moveable magnets to correct phase errors and on axis field integrals. The device is designed with a 5.0 cm period and will produce variably polarized light of any ellipticity, including pure circular and linear. The spectral range at 1.9 GeV for typical elliptical polarization with a degree of circular polarization greater than 0.8 will be from 100 eV to 1500 eV, using the third and fifth spectral harmonics. The device will be switchabe between left and right circular modes at a frequency of up to 0.1 Hz. The 1.95 m long overall length will allow two such devices in a single ALS straight sector.

Preparation and fabrication of a full-scale, sagittal-sliced, 3D-printed, patient-specific radiotherapy phantom.

PubMed

Craft, Daniel F; Howell, Rebecca M

2017-09-01

Patient-specific 3D-printed phantoms have many potential applications, both research and clinical. However, they have been limited in size and complexity because of the small size of most commercially available 3D printers as well as material warping concerns. We aimed to overcome these limitations by developing and testing an effective 3D printing workflow to fabricate a large patient-specific radiotherapy phantom with minimal warping errors. In doing so, we produced a full-scale phantom of a real postmastectomy patient. We converted a patient's clinical CT DICOM data into a 3D model and then sliced the model into eleven 2.5-cm-thick sagittal slices. The slices were printed with a readily available thermoplastic material representing all body tissues at 100% infill, but with air cavities left open. Each slice was printed on an inexpensive and commercially available 3D printer. Once the printing was completed, the slices were placed together for imaging and verification. The original patient CT scan and the assembled phantom CT scan were registered together to assess overall accuracy. The materials for the completed phantom cost $524. The printed phantom agreed well with both its design and the actual patient. Individual slices differed from their designs by approximately 2%. Registered CT images of the assembled phantom and original patient showed excellent agreement. Three-dimensional printing the patient-specific phantom in sagittal slices allowed a large phantom to be fabricated with high accuracy. Our results demonstrate that our 3D printing workflow can be used to make large, accurate, patient-specific phantoms at 100% infill with minimal material warping error. © 2017 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

Tissue-mimicking gel phantoms for thermal therapy studies.

PubMed

Dabbagh, Ali; Abdullah, Basri Johan Jeet; Ramasindarum, Chanthiriga; Abu Kasim, Noor Hayaty

2014-10-01

Tissue-mimicking phantoms that are currently available for routine biomedical applications may not be suitable for high-temperature experiments or calibration of thermal modalities. Therefore, design and fabrication of customized thermal phantoms with tailored properties are necessary for thermal therapy studies. A multitude of thermal phantoms have been developed in liquid, solid, and gel forms to simulate biological tissues in thermal therapy experiments. This article is an attempt to outline the various materials and techniques used to prepare thermal phantoms in the gel state. The relevant thermal, electrical, acoustic, and optical properties of these phantoms are presented in detail and the benefits and shortcomings of each type are discussed. This review could assist the researchers in the selection of appropriate phantom recipes for their in vitro study of thermal modalities and highlight the limitations of current phantom recipes that remain to be addressed in further studies. © The Author(s) 2014.

A phantom design for assessment of detectability in PET imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wollenweber, Scott D., E-mail: scott.wollenweber@g

2016-09-15

Purpose: The primary clinical role of positron emission tomography (PET) imaging is the detection of anomalous regions of {sup 18}F-FDG uptake, which are often indicative of malignant lesions. The goal of this work was to create a task-configurable fillable phantom for realistic measurements of detectability in PET imaging. Design goals included simplicity, adjustable feature size, realistic size and contrast levels, and inclusion of a lumpy (i.e., heterogeneous) background. Methods: The detection targets were hollow 3D-printed dodecahedral nylon features. The exostructure sphere-like features created voids in a background of small, solid non-porous plastic (acrylic) spheres inside a fillable tank. The featuresmore » filled at full concentration while the background concentration was reduced due to filling only between the solid spheres. Results: Multiple iterations of feature size and phantom construction were used to determine a configuration at the limit of detectability for a PET/CT system. A full-scale design used a 20 cm uniform cylinder (head-size) filled with a fixed pattern of features at a contrast of approximately 3:1. Known signal-present and signal-absent PET sub-images were extracted from multiple scans of the same phantom and with detectability in a challenging (i.e., useful) range. These images enabled calculation and comparison of the quantitative observer detectability metrics between scanner designs and image reconstruction methods. The phantom design has several advantages including filling simplicity, wall-less contrast features, the control of the detectability range via feature size, and a clinically realistic lumpy background. Conclusions: This phantom provides a practical method for testing and comparison of lesion detectability as a function of imaging system, acquisition parameters, and image reconstruction methods and parameters.« less

Comparative imaging study in ultrasound, MRI, CT, and DSA using a multimodality renal artery phantom

DOE Office of Scientific and Technical Information (OSTI.GOV)

King, Deirdre M.; Fagan, Andrew J.; Moran, Carmel M.

2011-02-15

Purpose: A range of anatomically realistic multimodality renal artery phantoms consisting of vessels with varying degrees of stenosis was developed and evaluated using four imaging techniques currently used to detect renal artery stenosis (RAS). The spatial resolution required to visualize vascular geometry and the velocity detection performance required to adequately characterize blood flow in patients suffering from RAS are currently ill-defined, with the result that no one imaging modality has emerged as a gold standard technique for screening for this disease. Methods: The phantoms, which contained a range of stenosis values (0%, 30%, 50%, 70%, and 85%), were designed formore » use with ultrasound, magnetic resonance imaging, x-ray computed tomography, and x-ray digital subtraction angiography. The construction materials used were optimized with respect to their ultrasonic speed of sound and attenuation coefficient, MR relaxometry (T{sub 1},T{sub 2}) properties, and Hounsfield number/x-ray attenuation coefficient, with a design capable of tolerating high-pressure pulsatile flow. Fiducial targets, incorporated into the phantoms to allow for registration of images among modalities, were chosen to minimize geometric distortions. Results: High quality distortion-free images of the phantoms with good contrast between vessel lumen, fiducial markers, and background tissue to visualize all stenoses were obtained with each modality. Quantitative assessments of the grade of stenosis revealed significant discrepancies between modalities, with each underestimating the stenosis severity for the higher-stenosed phantoms (70% and 85%) by up to 14%, with the greatest discrepancy attributable to DSA. Conclusions: The design and construction of a range of anatomically realistic renal artery phantoms containing varying degrees of stenosis is described. Images obtained using the main four diagnostic techniques used to detect RAS were free from artifacts and exhibited adequate contrast to allow for quantitative measurements of the degree of stenosis in each phantom. Such multimodality phantoms may prove useful in evaluating current and emerging US, MRI, CT, and DSA technology.« less

Dual photon absorptiometry using a gadolinium-153 source applied to measure equine bone mineral content

NASA Astrophysics Data System (ADS)

Moure, Alessandro; Reichmann, Peter; Remigio Gamba, Humberto

2003-12-01

The application of the dual photon absorptiometry (DPA) technique, using gadolinium-153 as the photon source, to evaluate the bone mineral density (BMD) of the third metacarpal bone of horses is presented. The radiation detector was implemented with a NaI(TI) scintillator coupled to a 14 stage photomultiplier. A modular mechanical system allows the position of the prototype to be adjusted in relation to the animal. A moveable carrier makes it possible to scan the third metacarpal with a velocity adjustable between 1 and 12 mm s-1, in steps of 1 mm s-1, for a total distance of 250 mm. The prototype was evaluated with a phantom of the third metacarpal bone made of perspex and aluminium, and in vitro with a transverse slice of the third metacarpal bone of a horse. The tests showed that the prototype has an accuracy and precision of, approximately, 10% and 6%, respectively, for a 6 s acquisition time. Preliminary studies carried out in three foals from birth to one year of age indicated that the prototype is well suited to in vivo and in situ analysis of the BMD of the third metacarpal bones of horses, making it possible to evaluate the changes of BMD levels on a monthly basis. Also, results indicated an exponential behaviour of the BMD curve during the first year of life of the studied horses.

Comparison of the ANSI, RSD, KKH, and BRMD thyroid-neck phantoms for 125I thyroid monitoring.

PubMed

Kramer, G H; Olender, G; Vlahovich, S; Hauck, B M; Meyerhof, D P

1996-03-01

The Human Monitoring Laboratory, which acts as the Canadian National Calibration Reference Centre for In Vivo Monitoring, has determined the performance characteristics of four thyroid phantoms for 125I thyroid monitoring. The phantoms were a phantom built to the specifications of the American National Standards Institute Standard N44.3; the phantom available from Radiology Support Devices; the phantom available from Kyoto Kagaku Hyohon; the phantom manufactured by the Human Monitoring Laboratory and known as the BRMD phantom. The counting efficiencies of the phantoms for 125I were measured at different phantom-to-detector distances. The anthropomorphic characteristics of the phantoms have been compared with the average man parameters. It was concluded that the BRMD, American National Standards Institute, and Radiology Support Devices phantoms have the same performance characteristics when the neck-to-detector distances are greater than 12 cm and all phantoms are essentially equivalent at 30 cm or more. The Kyoto Kagaku Hyohon phantom showed lower counting efficiencies at phantom-to-detector distances less than 30 cm. This was attributed to the design of the phantom. This study has also shown that the phantom need not be highly anthropomorphic provided the calibration is not performed at short neck-detector distances. Indeed, it might be possible to use t simple point source of 125I placed behind a 1.5 cm block of lucite at neck detector distances of 12 cm or more.

Generation of anatomically realistic numerical phantoms for photoacoustic and ultrasonic breast imaging

NASA Astrophysics Data System (ADS)

Lou, Yang; Zhou, Weimin; Matthews, Thomas P.; Appleton, Catherine M.; Anastasio, Mark A.

2017-04-01

Photoacoustic computed tomography (PACT) and ultrasound computed tomography (USCT) are emerging modalities for breast imaging. As in all emerging imaging technologies, computer-simulation studies play a critically important role in developing and optimizing the designs of hardware and image reconstruction methods for PACT and USCT. Using computer-simulations, the parameters of an imaging system can be systematically and comprehensively explored in a way that is generally not possible through experimentation. When conducting such studies, numerical phantoms are employed to represent the physical properties of the patient or object to-be-imaged that influence the measured image data. It is highly desirable to utilize numerical phantoms that are realistic, especially when task-based measures of image quality are to be utilized to guide system design. However, most reported computer-simulation studies of PACT and USCT breast imaging employ simple numerical phantoms that oversimplify the complex anatomical structures in the human female breast. We develop and implement a methodology for generating anatomically realistic numerical breast phantoms from clinical contrast-enhanced magnetic resonance imaging data. The phantoms will depict vascular structures and the volumetric distribution of different tissue types in the breast. By assigning optical and acoustic parameters to different tissue structures, both optical and acoustic breast phantoms will be established for use in PACT and USCT studies.

Design and development of an ultrasound calibration phantom and system

NASA Astrophysics Data System (ADS)

Cheng, Alexis; Ackerman, Martin K.; Chirikjian, Gregory S.; Boctor, Emad M.

2014-03-01

Image-guided surgery systems are often used to provide surgeons with informational support. Due to several unique advantages such as ease of use, real-time image acquisition, and no ionizing radiation, ultrasound is a common medical imaging modality used in image-guided surgery systems. To perform advanced forms of guidance with ultrasound, such as virtual image overlays or automated robotic actuation, an ultrasound calibration process must be performed. This process recovers the rigid body transformation between a tracked marker attached to the ultrasound transducer and the ultrasound image. A phantom or model with known geometry is also required. In this work, we design and test an ultrasound calibration phantom and software. The two main considerations in this work are utilizing our knowledge of ultrasound physics to design the phantom and delivering an easy to use calibration process to the user. We explore the use of a three-dimensional printer to create the phantom in its entirety without need for user assembly. We have also developed software to automatically segment the three-dimensional printed rods from the ultrasound image by leveraging knowledge about the shape and scale of the phantom. In this work, we present preliminary results from using this phantom to perform ultrasound calibration. To test the efficacy of our method, we match the projection of the points segmented from the image to the known model and calculate a sum squared difference between each point for several combinations of motion generation and filtering methods. The best performing combination of motion and filtering techniques had an error of 1.56 mm and a standard deviation of 1.02 mm.

New ANSI standard for thyroid phantom

DOE PAGES

Mallett, Michael W.; Bolch, Wesley E.; Fulmer, Philip C.; ...

2015-08-01

Here, a new ANSI standard titled “Thyroid Phantom Used in Occupational Monitoring” (Health Physics Society 2014) has been published. The standard establishes the criteria for acceptable design, fabrication, or modeling of a phantom suitable for calibrating in vivo monitoring systems to measure photon-emitting radionuclides deposited in the thyroid. The current thyroid phantom standard was drafted in 1973 (ANSI N44.3-1973), last reviewed in 1984, and a revision of the standard to cover a more modern approach was deemed warranted.

Microwave Interferometric Density Measurements of a Pulsed Helicon Source

NASA Astrophysics Data System (ADS)

Scime, Ethan; Scime, Earl; Thompson, Derek

2017-10-01

The intense rf environment of a helicon plasma source is problematic for electrostatic probe measurements of plasma density, particularly at low neutral pressures. Here we present measurements of the line-integrated plasma density in a helicon plasma source using a multi-frequency (20-40 GHz) microwave interferometer. The design of the diagnostic and the data acquisition system are presented, as well as a comparison to density profiles obtained with a moveable electrostatic probe. A parametric fit to the probe profile measurements is used to determine the peak density from the microwave density measurements. This work supported by U.S. National Science Foundation Grant No. PHY-1360278.

Fabricating optical phantoms to simulate skin tissue properties and microvasculatures

NASA Astrophysics Data System (ADS)

Sheng, Shuwei; Wu, Qiang; Han, Yilin; Dong, Erbao; Xu, Ronald

2015-03-01

This paper introduces novel methods to fabricate optical phantoms that simulate the morphologic, optical, and microvascular characteristics of skin tissue. The multi-layer skin-simulating phantom was fabricated by a light-cured 3D printer that mixed and printed the colorless light-curable ink with the absorption and the scattering ingredients for the designated optical properties. The simulated microvascular network was fabricated by a soft lithography process to embed microchannels in polydimethylsiloxane (PDMS) phantoms. The phantoms also simulated vascular anomalies and hypoxia commonly observed in cancer. A dual-modal multispectral and laser speckle imaging system was used for oxygen and perfusion imaging of the tissue-simulating phantoms. The light-cured 3D printing technique and the soft lithography process may enable freeform fabrication of skin-simulating phantoms that embed microvessels for image and drug delivery applications.

MO-B-BRD-01: Creation of 3D Printed Phantoms for Clinical Radiation Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ehler, E.

This session is designed so that the learning objectives are practical. The intent is that the attendee may take home an understanding of not just the technology, but also the logistical steps necessary to execute these 3D printing techniques in the clinic. Four practical 3D printing topics will be discussed: (i) Creating bolus and compensators for photon machines; (ii) tools for proton therapy; (iii) clinical applications in imaging; (iv) custom phantom design for clinic and research use. The use of 3D printers within the radiation oncology setting is proving to be a useful tool for creating patient specific bolus andmore » compensators with the added benefit of cost savings. Creating the proper protocol is essential to ensuring that the desired effect is achieved and modeled in the treatment planning system. The critical choice of printer material (since it determines the interaction with the radiation) will be discussed. Selection of 3D printer type, design methods, verification of dose calculation, and the printing process will be detailed to give the basis for establishing your own protocol for electron and photon fields. A practical discussion of likely obstacles that may be encountered will be included. The diversity of systems and techniques in proton facilities leads to different facilities having very different requirements for beam modifying hardware and quality assurance devices. Many departments find the need to design and fabricate facility-specific equipment, making 3D printing an attractive technology. 3D printer applications in proton therapy will be discussed, including beam filters and compensators, and the design of proton therapy specific quality assurance tools. Quality control specific to 3D printing in proton therapy will be addressed. Advantages and disadvantages of different printing technology for these applications will also be discussed. 3D printing applications using high-resolution radiology-based imaging data will be presented. This data is used to 3D print individualized physical models of patient’s unique anatomy for aid in planning complex and challenging surgical procedures. Methods, techniques and imaging requirements for 3D printing anatomic models from imaging data will be discussed. Specific applications currently being used in the radiology clinic will be detailed. Standardized phantoms for radiation therapy are abundant. However, custom phantom designs can be advantageous for both clinical tasks and research. 3D printing is a useful method of custom fabrication that allows one to construct custom objects relatively quickly. Possibilities for custom radiotherapy phantoms range from 3D printing a hollow shell and filling the shell with tissue equivalent materials to fully printing the entire phantom with materials that are tissue equivalent as well as suitable for 3D printing. A range of materials available for use in radiotherapy phantoms and in the case of phantoms for dosimetric measurements, this choice is critical. The necessary steps required will be discussed including: modalities of 3D model generation, 3D model requirements for 3D printing, generation of machine instructions from the 3D model, and 3D printing techniques, choice of phantoms material, and troubleshooting techniques for each step in the process. Case examples of 3D printed phantoms will be shown. Learning Objectives: Understand the types of 3D modeling software required to design your device, the file formats required for data transfer from design software to 3D printer, and general troubleshooting techniques for each step of the process. Learn the differences between materials and design for photons vs. electrons vs. protons. Understand the importance of material choice and design geometries for your custom phantoms. Learn specific steps of quality assurance and quality control for 3D printed beam filters and compensators for proton therapy. Learn of special 3D printing applications for imaging. Cunha: Research support from Phillips Healthcare.« less

Neutrino-4 experiment on search for sterile neutrino with multi-section model of detector

NASA Astrophysics Data System (ADS)

Serebrov, A.; Ivochkin, V.; Samoilov, R.; Fomin, A.; Polyushkin, A.; Zinoviev, V.; Neustroev, P.; Golovtsov, V.; Chernyj, A.; Zherebtsov, O.; Martemyanov, V.; Tarasenkov, V.; Aleshin, V.; Petelin, A.; Izhutov, A.; Tuzov, A.; Sazontov, S.; Ryazanov, D.; Gromov, M.; Afanasiev, V.; Zaytsev, M.; Chaikovskii, M.

2017-09-01

In order to carry out research in the field of possible existence of a sterile neutrino the laboratory based on SM-3 reactor (Dimitrovgrad, Russia) was created to search for oscillations of reactor antineutrino. The prototype of a multi-section neutrino detector with liquid scintillator volume of 350 l was installed in the middle of 2015. It is a moveable inside the passive shielding detector, which can be set at distance range from 6 to 11 meters from the reactor core. Measurements of antineutrino flux at such small distances from the reactor core are carried out with moveable detector for the first time. The measurements carried out with detector prototype demonstrated a possibility of measuring a reactor antineutrino flux in difficult conditions of cosmic background at Earth surface.

Conical Seat Shut-Off Valve

NASA Technical Reports Server (NTRS)

Farner, Bruce

2013-01-01

A moveable valve for controlling flow of a pressurized working fluid was designed. This valve consists of a hollow, moveable floating piston pressed against a stationary solid seat, and can use the working fluid to seal the valve. This open/closed, novel valve is able to use metal-to-metal seats, without requiring seat sliding action; therefore there are no associated damaging effects. During use, existing standard high-pressure ball valve seats tend to become damaged during rotation of the ball. Additionally, forces acting on the ball and stem create large amounts of friction. The combination of these effects can lead to system failure. In an attempt to reduce damaging effects and seat failures, soft seats in the ball valve have been eliminated; however, the sliding action of the ball across the highly loaded seat still tends to scratch the seat, causing failure. Also, in order to operate, ball valves require the use of large actuators. Positioning the metal-to-metal seats requires more loading, which tends to increase the size of the required actuator, and can also lead to other failures in other areas such as the stem and bearing mechanisms, thus increasing cost and maintenance. This novel non-sliding seat surface valve allows metal-to-metal seats without the damaging effects that can lead to failure, and enables large seating forces without damaging the valve. Additionally, this valve design, even when used with large, high-pressure applications, does not require large conventional valve actuators and the valve stem itself is eliminated. Actuation is achieved with the use of a small, simple solenoid valve. This design also eliminates the need for many seals used with existing ball valve and globe valve designs, which commonly cause failure, too. This, coupled with the elimination of the valve stem and conventional valve actuator, improves valve reliability and seat life. Other mechanical liftoff seats have been designed; however, they have only resulted in increased cost, and incurred other reliability issues. With this novel design, the seat is lifted by simply removing the working fluid pressure that presses it against the seat and no external force is required. By eliminating variables associated with existing ball and globe configurations that can have damaging effects upon a valve, this novel design reduces downtime in rocket engine test schedules and maintenance costs.

Temperature field simulation and phantom validation of a Two-armed Spiral Antenna for microwave thermotherapy.

PubMed

Du, Yongxing; Zhang, Lingze; Sang, Lulu; Wu, Daocheng

2016-04-29

In this paper, an Archimedean planar spiral antenna for the application of thermotherapy was designed. This type of antenna was chosen for its compact structure, flexible application and wide heating area. The temperature field generated by the use of this Two-armed Spiral Antenna in a muscle-equivalent phantom was simulated and subsequently validated by experimentation. First, the specific absorption rate (SAR) of the field was calculated using the Finite Element Method (FEM) by Ansoft's High Frequency Structure Simulation (HFSS). Then, the temperature elevation in the phantom was simulated by an explicit finite difference approximation of the bioheat equation (BHE). The temperature distribution was then validated by a phantom heating experiment. The results showed that this antenna had a good heating ability and a wide heating area. A comparison between the calculation and the measurement showed a fair agreement in the temperature elevation. The validated model could be applied for the analysis of electromagnetic-temperature distribution in phantoms during the process of antenna design or thermotherapy experimentation.

Design, fabrication, and implementation of voxel-based 3D printed textured phantoms for task-based image quality assessment in CT

NASA Astrophysics Data System (ADS)

Solomon, Justin; Ba, Alexandre; Diao, Andrew; Lo, Joseph; Bier, Elianna; Bochud, François; Gehm, Michael; Samei, Ehsan

2016-03-01

In x-ray computed tomography (CT), task-based image quality studies are typically performed using uniform background phantoms with low-contrast signals. Such studies may have limited clinical relevancy for modern non-linear CT systems due to possible influence of background texture on image quality. The purpose of this study was to design and implement anatomically informed textured phantoms for task-based assessment of low-contrast detection. Liver volumes were segmented from 23 abdominal CT cases. The volumes were characterized in terms of texture features from gray-level co-occurrence and run-length matrices. Using a 3D clustered lumpy background (CLB) model, a fitting technique based on a genetic optimization algorithm was used to find the CLB parameters that were most reflective of the liver textures, accounting for CT system factors of spatial blurring and noise. With the modeled background texture as a guide, a cylinder phantom (165 mm in diameter and 30 mm height) was designed, containing 20 low-contrast spherical signals (6 mm in diameter at targeted contrast levels of ~3.2, 5.2, 7.2, 10, and 14 HU, 4 repeats per signal). The phantom was voxelized and input into a commercial multi-material 3D printer (Object Connex 350), with custom software for voxel-based printing. Using principles of digital half-toning and dithering, the 3D printer was programmed to distribute two base materials (VeroWhite and TangoPlus, nominal voxel size of 42x84x30 microns) to achieve the targeted spatial distribution of x-ray attenuation properties. The phantom was used for task-based image quality assessment of a clinically available iterative reconstruction algorithm (Sinogram Affirmed Iterative Reconstruction, SAFIRE) using a channelized Hotelling observer paradigm. Images of the textured phantom and a corresponding uniform phantom were acquired at six dose levels and observer model performance was estimated for each condition (5 contrasts x 6 doses x 2 reconstructions x 2 backgrounds = 120 total conditions). Based on the observer model results, the dose reduction potential of SAFIRE was computed and compared between the uniform and textured phantom. The dose reduction potential of SAFIRE was found to be 23% based on the uniform phantom and 17% based on the textured phantom. This discrepancy demonstrates the need to consider background texture when assessing non-linear reconstruction algorithms.

TomoPhantom, a software package to generate 2D-4D analytical phantoms for CT image reconstruction algorithm benchmarks

NASA Astrophysics Data System (ADS)

Kazantsev, Daniil; Pickalov, Valery; Nagella, Srikanth; Pasca, Edoardo; Withers, Philip J.

2018-01-01

In the field of computerized tomographic imaging, many novel reconstruction techniques are routinely tested using simplistic numerical phantoms, e.g. the well-known Shepp-Logan phantom. These phantoms cannot sufficiently cover the broad spectrum of applications in CT imaging where, for instance, smooth or piecewise-smooth 3D objects are common. TomoPhantom provides quick access to an external library of modular analytical 2D/3D phantoms with temporal extensions. In TomoPhantom, quite complex phantoms can be built using additive combinations of geometrical objects, such as, Gaussians, parabolas, cones, ellipses, rectangles and volumetric extensions of them. Newly designed phantoms are better suited for benchmarking and testing of different image processing techniques. Specifically, tomographic reconstruction algorithms which employ 2D and 3D scanning geometries, can be rigorously analyzed using the software. TomoPhantom also provides a capability of obtaining analytical tomographic projections which further extends the applicability of software towards more realistic, free from the "inverse crime" testing. All core modules of the package are written in the C-OpenMP language and wrappers for Python and MATLAB are provided to enable easy access. Due to C-based multi-threaded implementation, volumetric phantoms of high spatial resolution can be obtained with computational efficiency.

Directly detected 55Mn MRI: Application to phantoms for human hyperpolarized 13C MRI development

PubMed Central

von Morze, Cornelius; Carvajal, Lucas; Reed, Galen D.; Swisher, Christine Leon; Tropp, James; Vigneron, Daniel B.

2014-01-01

In this work we demonstrate for the first time directly detected manganese-55 (55Mn) MRI using a clinical 3T MRI scanner designed for human hyperpolarized 13C clinical studies with no additional hardware modifications. Due to the similar frequency of the 55Mn and 13C resonances, the use of aqueous permanganate for large, signal-dense, and cost-effective “13C” MRI phantoms was investigated, addressing the clear need for new phantoms for these studies. Due to 100% natural abundance, higher intrinsic sensitivity, and favorable relaxation properties, 55Mn MRI of aqueous permanganate demonstrates dramatically increased sensitivity over typical 13C phantom MRI, at greatly reduced cost as compared with large 13C-enriched phantoms. A large sensitivity advantage (22-fold) was demonstrated. A cylindrical phantom (d= 8 cm) containing concentrated aqueous sodium permanganate (2.7M) was scanned rapidly by 55Mn MRI in a human head coil tuned for 13C, using a balanced SSFP acquisition. The requisite penetration of RF magnetic fields into concentrated permanganate was investigated by experiments and high frequency electromagnetic simulations, and found to be sufficient for 55Mn MRI with reasonably sized phantoms. A sub-second slice-selective acquisition yielded mean image SNR of ~60 at 0.5cm3 spatial resolution, distributed with minimum central signal ~40% of the maximum edge signal. We anticipate that permanganate phantoms will be very useful for testing HP 13C coils and methods designed for human studies. PMID:25179135

A proto-type design of a real-tissue phantom for the validation of deformation algorithms and 4D dose calculations

NASA Astrophysics Data System (ADS)

Szegedi, M.; Rassiah-Szegedi, P.; Fullerton, G.; Wang, B.; Salter, B.

2010-07-01

The purpose of this study is to design a real-tissue phantom for use in the validation of deformation algorithms. A phantom motion controller that runs sinusoidal and non-regular patient-based breathing pattern, via a piston, was applied to porcine liver tissue. It was regulated to simulate movement ranges similar to recorded implanted liver markers from patients. 4D CT was applied to analyze deformation. The suitability of various markers in the liver and the position reproducibility of markers and of reference points were studied. The similarity of marker motion pattern in the liver phantom and in real patients was evaluated. The viability of the phantom over time and its use with electro-magnetic tracking devices were also assessed. High contrast markers, such as carbon markers, implanted in the porcine liver produced less image artifacts on CT and were well visualized compared to metallic ones. The repositionability of markers was within a measurement accuracy of ±2 mm. Similar anatomical patient motions were reproducible up to elongations of 3 cm for a time period of at least 90 min. The phantom is compatible with electro-magnetic tracking devices and 4D CT. The phantom motion is reproducible and simulates realistic patient motion and deformation. The ability to carry out voxel-based tracking allows for the evaluation of deformation algorithms in a controlled environment with recorded patient traces. The phantom is compatible with all therapy devices clinically encountered in our department.

Adjustable fetal phantom for pulse oximetry

NASA Astrophysics Data System (ADS)

Stubán, Norbert; Niwayama, Masatsugu

2009-05-01

As the measuring head of a fetal pulse oximeter must be attached to the head of the fetus inside the mother's uterus during labor, testing, and developing of fetal pulse oximeters in real environment have several difficulties. A fetal phantom could enable evaluation of pulse oximeters in a simulated environment without the restrictions and difficultness of medical experiments in the labor room. Based on anatomic data we developed an adjustable fetal head phantom with three different tissue layers and artificial arteries. The phantom consisted of two arteries with an inner diameter of 0.2 and 0.4 mm. An electronically controlled pump produced pulse waves in the arteries. With the phantom we investigated the sensitivity of a custom-designed wireless pulse oximeter at different pulsation intensity and artery diameters. The results showed that the oximeter was capable of identifying 4% and 2% changes in diameter between the diastolic and systolic point in arteries of over 0.2 and 0.4 mm inner diameter, respectively. As the structure of the phantom is based on reported anatomic values, the results predict that the investigated custom-designed wireless pulse oximeter has sufficient sensitivity to detect the pulse waves and to calculate the R rate on the fetal head.

Technical Note: Development of a 3D printed subresolution sandwich phantom for validation of brain SPECT analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Negus, Ian S.; Holmes, Robin B.; Thorne, Gareth C.

Purpose: To make an adaptable, head shaped radionuclide phantom to simulate molecular imaging of the brain using clinical acquisition and reconstruction protocols. This will allow the characterization and correction of scanner characteristics, and improve the accuracy of clinical image analysis, including the application of databases of normal subjects. Methods: A fused deposition modeling 3D printer was used to create a head shaped phantom made up of transaxial slabs, derived from a simulated MRI dataset. The attenuation of the printed polylactide (PLA), measured by means of the Hounsfield unit on CT scanning, was set to match that of the brain bymore » adjusting the proportion of plastic filament and air (fill ratio). Transmission measurements were made to verify the attenuation of the printed slabs. The radionuclide distribution within the phantom was created by adding {sup 99m}Tc pertechnetate to the ink cartridge of a paper printer and printing images of gray and white matter anatomy, segmented from the same MRI data. The complete subresolution sandwich phantom was assembled from alternate 3D printed slabs and radioactive paper sheets, and then imaged on a dual headed gamma camera to simulate an HMPAO SPECT scan. Results: Reconstructions of phantom scans successfully used automated ellipse fitting to apply attenuation correction. This removed the variability inherent in manual application of attenuation correction and registration inherent in existing cylindrical phantom designs. The resulting images were assessed visually and by count profiles and found to be similar to those from an existing elliptical PMMA phantom. Conclusions: The authors have demonstrated the ability to create physically realistic HMPAO SPECT simulations using a novel head-shaped 3D printed subresolution sandwich method phantom. The phantom can be used to validate all neurological SPECT imaging applications. A simple modification of the phantom design to use thinner slabs would make it suitable for use in PET.« less

DEVELOPMENT OF A SET OF MESH-BASED AND AGE-DEPENDENT CHINESE PHANTOMS AND APPLICATION FOR CT DOSE CALCULATIONS.

PubMed

Pi, Yifei; Liu, Tianyu; Xu, X George

2018-06-01

Phantoms for organ dose calculations are essential in radiation protection dosimetry. This article describes the development of a set of mesh-based and age-dependent phantoms for Chinese populations using reference data recommended by the Chinese government and by the International Atomic Energy Agency (IAEA). Existing mesh-based RPI adult male (RPI-AM) and RPI adult female (RPI-AF) phantoms were deformed to form new phantoms according to anatomical data for the height and weight of Chinese individuals of 5 years old male, 5 years old female, 10 years old male, 10 years old female,15 years old male, 15 years old female, adult male and adult female-named USTC-5 M, USTC-5F, USTC-10M, USTC-10F, USTC-15M, USTC-15F, USTC-AM and USTC-AF, respectively. Following procedures to ensure the accuracy, more than 120 organs/tissues in each model were adjusted to match the Chinese reference parameters and the mass errors were within 0.5%. To demonstrate the usefulness, these new set of phantoms were combined with a fully validated model of the GE LightSpeed Pro 16 multi-detector computed tomography (MDCT) scanner and the GPU-based ARCHER Monte Carlo code to compute organ doses from CT examinations. Organ doses for adult models were then compared with the data of RPI-AM and RPI-AF under the same conditions. The absorbed doses and the effective doses of RPI phantoms are found to be lower than these of the USTC adult phantoms whose body sizes are smaller. Comparisons for the doses among different ages and genders were also made. It was found that teenagers receive more radiation doses than adults do. Such Chinese-specific phantoms are clearly better suited in organ dose studies for the Chinese individuals than phantoms designed for western populations. As already demonstrated, data derived from age-specific Chinese phantoms can help CT operators and designers to optimize image quality and doses.

SU-F-T-168: Development and Implementation of An Anthropomorphic Head & Neck Phantom for the Assessment of Proton Therapy Treatment Procedures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Branco, D; Taylor, P; Frank, S

2016-06-15

Purpose: To design a Head and Neck (H&N) anthropomorphic QA phantom that the Imaging and Radiation Oncology Core Houston (IROC-H) can use to verify the quality of intensity modulated proton therapy (IMPT) H&N treatments for institutions participating in NCI clinical trials. Methods: The phantom was created to serve as a remote auditing tool for IROC-H to evaluate an institution’s IMPT planning and delivery abilities. The design was based on the composition, size, and geometry of a generalized oropharyngeal tumor and contains critical structures (parotids and spinal cord). Radiochromic film in the axial and sagittal planes and thermoluminescent dosimeters (TLD)-100 capsulesmore » were embedded in the phantom and used to perform the dose delivery evaluation. A CT simulation was used to create a passive scatter and a spot scanning treatment plan with typical clinical constraints for H&N cancer. The IMPT plan was approved by a radiation oncologist and the phantom was irradiated multiple times. The measured dose distribution using a 7%/4mm gamma analysis (85% of pixels passing) and point doses were compared with the treatment planning system calculations. Results: The designed phantom could not achieve the target dose prescription and organ at risk dose constraints with the passive scatter treatment plan. The target prescription dose could be met but not the parotid dose constraint. The average TLD point dose ratio in the target was 0.975, well within the 5% acceptance criterion. The dose distribution analysis using various acceptance criteria, 5%/4mm, 5%/3mm, 7%/4mm and 7%/5mm, had average pixel passing rates of 85.9%, 81.8%, 89.6% and 91.6%, and respectively. Conclusion: An anthropomorphic IMPT H&N phantom was designed that can assess the dose delivery of proton sites wishing to participate in clinical trials using a 5% TLD dose and 7%/4mm gamma analysis acceptance criteria.« less

A Moveable Med School.

ERIC Educational Resources Information Center

Lawrence, Susan V.

1979-01-01

This is a report on the American University of the Caribbean School of Medicine, which is operating in Cincinnati despite more than six months of legal and administrative battles with Ohio educational authorities. (BB)

Design of an Image Fusion Phantom for a Small Animal microPET/CT Scanner Prototype

NASA Astrophysics Data System (ADS)

Nava-García, Dante; Alva-Sánchez, Héctor; Murrieta-Rodríguez, Tirso; Martínez-Dávalos, Arnulfo; Rodríguez-Villafuerte, Mercedes

2010-12-01

Two separate microtomography systems recently developed at Instituto de Física, UNAM, produce anatomical (microCT) and physiological images (microPET) of small animals. In this work, the development and initial tests of an image fusion method based on fiducial markers for image registration between the two modalities are presented. A modular Helix/Line-Sources phantom was designed and constructed; this phantom contains fiducial markers that can be visualized in both imaging systems. The registration was carried out by solving the rigid body alignment problem of Procrustes to obtain rotation and translation matrices required to align the two sets of images. The microCT/microPET image fusion of the Helix/Line-Sources phantom shows excellent visual coincidence between different structures, showing a calculated target-registration-error of 0.32 mm.

Performance assessment of an opto-fluidic phantom mimicking porcine liver parenchyma

NASA Astrophysics Data System (ADS)

Akl, Tony J.; King, Travis J.; Long, Ruiqi; McShane, Michael J.; Nance Ericson, M.; Wilson, Mark A.; Coté, Gerard L.

2012-07-01

An implantable, optical oxygenation and perfusion sensor to monitor liver transplants during the two-week period following the transplant procedure is currently being developed. In order to minimize the number of animal experiments required for this research, a phantom that mimics the optical, anatomical, and physiologic flow properties of liver parenchyma is being developed as well. In this work, the suitability of this phantom for liver parenchyma perfusion research was evaluated by direct comparison of phantom perfusion data with data collected from in vivo porcine studies, both using the same prototype perfusion sensor. In vitro perfusion and occlusion experiments were performed on a single-layer and on a three-layer phantom perfused with a dye solution possessing the absorption properties of oxygenated hemoglobin. While both phantoms exhibited response patterns similar to the liver parenchyma, the signal measured from the multilayer phantom was three times higher than the single layer phantom and approximately 21 percent more sensitive to in vitro changes in perfusion. Although the multilayer phantom replicated the in vivo flow patterns more closely, the data suggests that both phantoms can be used in vitro to facilitate sensor design.

Extension of DQE to include scatter, grid, magnification, and focal spot blur: a new experimental technique and metric

NASA Astrophysics Data System (ADS)

Ranger, N. T.; Mackenzie, A.; Honey, I. D.; Dobbins, J. T., III; Ravin, C. E.; Samei, E.

2009-02-01

In digital radiography, conventional DQE evaluations are performed under idealized conditions that do not reflect typical clinical operating conditions. For this reason, we have developed and evaluated an experimental methodology for measuring theeffective detective quantum efficiency (eDQE) of digital radiographic systems and its utility in chest imaging applications.To emulate the attenuation and scatter properties of the human thorax across a range of sizes, the study employed pediatric and adult geometric chest imaging phantoms designed for use in the FDA/CDRH Nationwide Evaluation of X-Ray Trends (NEXT) program and a third phantom configuration designed to represent the bariatric population. The MTF for each phantom configuration was measured using images of an opaque edge device placed at the nominal surface of each phantom and at a common reference point. For each phantom, the NNPS was measured in a uniform region within the phantom image acquired at an exposure level determined from a prior phototimed acquisition. Scatter measurements were made using a beam-stop technique. These quantities were used along with measures of phantom attenuation and estimates of x-ray flux, to compute the eDQE at the beam-entrance surface of the phantoms, reflecting the presence of scatter, grid, magnification, and focal spot blur. The MTF results showed notable degradation due to focal spot blurring enhanced by geometric magnification, with increasing phantom size. Measured scatter fractions were 33%, 34% and 46% for the pediatric, adult, and bariatric phantoms, respectively. Correspondingly, the measured narrow beam transmission fractions were 16%, 9%, and 3%. The eDQE results for the pediatric and adult phantoms correlate well at low spatial frequencies but show degradation in the eDQE at increasing spatial frequencies for the adult phantom in comparison to the pediatric phantom. The results for the bariatric configuration showed a marked decrease in eDQE in comparison to the adult phantom results, across all spatial frequencies, attributable to the combined differences in geometric magnification, and scatter. The eDQE metric has been demonstrated to be sensitive to body habitus suggesting its usefulness in assessing system response across a range of chest sizes and potentially making it a useful factor in protocol assessment and optimization.

SU-E-T-563: Multi-Fraction Stereotactic Radiosurgery with Extend System of Gamma Knife: Treatment Verification Using Indigenously Designed Patient Simulating Multipurpose Phantom

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bisht, R; Kale, S; Gopishankar, N

2015-06-15

Purpose: Aim of the study is to evaluate mechanical and radiological accuracy of multi-fraction regimen and validate Gamma knife based fractionation using newly developed patient simulating multipurpose phantom. Methods: A patient simulating phantom was designed to verify fractionated treatments with extend system (ES) of Gamma Knife however it could be used to validate other radiotherapy procedures as well. The phantom has options to insert various density material plugs and mini CT/MR distortion phantoms to analyze the quality of stereotactic imaging. An additional thorax part designed to predict surface doses at various organ sites. The phantom was positioned using vacuum headmore » cushion and patient control unit for imaging and treatment. The repositioning check tool (RCT) was used to predict phantom positioning under ES assembly. The phantom with special inserts for film in axial, coronal and sagittal plane were scanned with X-Ray CT and the acquired images were transferred to treatment planning system (LGP 10.1). The focal precession test was performed with 4mm collimator and an experimental plan of four 16mm collimator shots was prepared for treatment verification of multi-fraction regimen. The prescription dose of 5Gy per fraction was delivered in four fractions. Each fraction was analyzed using EBT3 films scanned with EPSON 10000XL Scanner. Results: The measurement of 38 RCT points showed an overall positional accuracy of 0.28mm. The mean deviation of 0.28% and 0.31 % were calculated as CT and MR image distortion respectively. The radiological focus accuracy test showed its deviation from mechanical center point of 0.22mm. The profile measurement showed close agreement between TPS planned and film measured dose. At tolerance criteria of 1%/1mm gamma index analysis showed a pass rate of > 95%. Conclusion: Our results show that the newly developed multipurpose patient simulating phantom is highly suitable for the verification of fractionated stereotactic radiosurgery using ES of Gamma knife. The study is a part of intramural research project of Research Section, All India Institute of Medical Sciences New Delhi India (A 247)« less

An anthropomorphic abdominal phantom for deformable image registration accuracy validation in adaptive radiation therapy.

PubMed

Liao, Yuliang; Wang, Linjing; Xu, Xiangdong; Chen, Haibin; Chen, Jiawei; Zhang, Guoqian; Lei, Huaiyu; Wang, Ruihao; Zhang, Shuxu; Gu, Xuejun; Zhen, Xin; Zhou, Linghong

2017-06-01

To design and construct a three-dimensional (3D) anthropomorphic abdominal phantom for geometric accuracy and dose summation accuracy evaluations of deformable image registration (DIR) algorithms for adaptive radiation therapy (ART). Organ molds, including liver, kidney, spleen, stomach, vertebra, and two metastasis tumors, were 3D printed using contours from an ovarian cancer patient. The organ molds were molded with deformable gels made of different mixtures of polyvinyl chloride (PVC) and the softener dioctyl terephthalate. Gels with different densities were obtained by a polynomial fitting curve that described the relation between the Hounsfield unit (HU) and PVC-softener blending ratio. The rigid vertebras were constructed by molding of white cement and cellulose pulp. The final abdominal phantom was assembled by arranging all the fabricated organs inside a hollow dummy according to their anatomies, and sealed by deformable gel with averaged HU of muscle and fat. Fiducial landmarks were embedded inside the phantom for spatial accuracy and dose accumulation accuracy studies. Two channels were excavated to facilitate ionization chamber insertion for dosimetric measurements. Phantom properties such as deformable gel elasticity and HU stability were studied. The dosimetric measurement accuracy in the phantom was performed, and the DIR accuracies of three DIR algorithms available in the open source DIR toolkit-DIRART were also validated. The constructed deformable gel showed elastic behavior and was stable in HU values over times, proving to be a practical material for the deformable phantom. The constructed abdominal phantom consisted of realistic anatomies in terms of both anatomical shapes and densities when compared with its reference patient. The dosimetric measurements showed a good agreement with the calculated doses from the treatment planning system. Fiducial-based accuracy analysis conducted on the constructed phantom demonstrated the feasibility of applying the phantom for organ-wise DIR accuracy assessment. We have designed and constructed an anthropomorphic abdominal deformable phantom with satisfactory elastic property, realistic organ density, and anatomy. This physical phantom can be used for routine validations of DIR geometric accuracy and dose accumulation accuracy in ART. © 2017 American Association of Physicists in Medicine.

MO-F-CAMPUS-I-02: Accuracy in Converting the Average Breast Dose Into the Mean Glandular Dose (MGD) Using the F-Factor in Cone Beam Breast CT- a Monte Carlo Study Using Homogeneous and Quasi-Homogeneous Phantoms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lai, C; Zhong, Y; Wang, T

2015-06-15

Purpose: To investigate the accuracy in estimating the mean glandular dose (MGD) for homogeneous breast phantoms by converting from the average breast dose using the F-factor in cone beam breast CT. Methods: EGSnrc-based Monte Carlo codes were used to estimate the MGDs. 13-cm in diameter, 10-cm high hemi-ellipsoids were used to simulate pendant-geometry breasts. Two different types of hemi-ellipsoidal models were employed: voxels in quasi-homogeneous phantoms were designed as either adipose or glandular tissue while voxels in homogeneous phantoms were designed as the mixture of adipose and glandular tissues. Breast compositions of 25% and 50% volume glandular fractions (VGFs), definedmore » as the ratio of glandular tissue voxels to entire breast voxels in the quasi-homogeneous phantoms, were studied. These VGFs were converted into glandular fractions by weight and used to construct the corresponding homogeneous phantoms. 80 kVp x-rays with a mean energy of 47 keV was used in the simulation. A total of 109 photons were used to image the phantoms and the energies deposited in the phantom voxels were tallied. Breast doses in homogeneous phantoms were averaged over all voxels and then used to calculate the MGDs using the F-factors evaluated at the mean energy of the x-rays. The MGDs for quasi-homogeneous phantoms were computed directly by averaging the doses over all glandular tissue voxels. The MGDs estimated for the two types of phantoms were normalized to the free-in-air dose at the iso-center and compared. Results: The normalized MGDs were 0.756 and 0.732 mGy/mGy for the 25% and 50% VGF homogeneous breasts and 0.761 and 0.733 mGy/mGy for the corresponding quasi-homogeneous breasts, respectively. The MGDs estimated for the two types of phantoms were similar within 1% in this study. Conclusion: MGDs for homogeneous breast models may be adequately estimated by converting from the average breast dose using the F-factor.« less

A custom-built PET phantom design for quantitative imaging of printed distributions.

PubMed

Markiewicz, P J; Angelis, G I; Kotasidis, F; Green, M; Lionheart, W R; Reader, A J; Matthews, J C

2011-11-07

This note presents a practical approach to a custom-made design of PET phantoms enabling the use of digital radioactive distributions with high quantitative accuracy and spatial resolution. The phantom design allows planar sources of any radioactivity distribution to be imaged in transaxial and axial (sagittal or coronal) planes. Although the design presented here is specially adapted to the high-resolution research tomograph (HRRT), the presented methods can be adapted to almost any PET scanner. Although the presented phantom design has many advantages, a number of practical issues had to be overcome such as positioning of the printed source, calibration, uniformity and reproducibility of printing. A well counter (WC) was used in the calibration procedure to find the nonlinear relationship between digital voxel intensities and the actual measured radioactive concentrations. Repeated printing together with WC measurements and computed radiography (CR) using phosphor imaging plates (IP) were used to evaluate the reproducibility and uniformity of such printing. Results show satisfactory printing uniformity and reproducibility; however, calibration is dependent on the printing mode and the physical state of the cartridge. As a demonstration of the utility of using printed phantoms, the image resolution and quantitative accuracy of reconstructed HRRT images are assessed. There is very good quantitative agreement in the calibration procedure between HRRT, CR and WC measurements. However, the high resolution of CR and its quantitative accuracy supported by WC measurements made it possible to show the degraded resolution of HRRT brain images caused by the partial-volume effect and the limits of iterative image reconstruction.

Status of Experiment NEUTRINO-4 Search for Sterile Neutrino

NASA Astrophysics Data System (ADS)

Serebrov, A.; Ivochkin, V.; Samoilov, R.; Fomin, A.; Polyushkin, A.; Zinoviev, V.; Neustroev, P.; Golovtsov, V.; Chernyj, A.; Zherebtsov, O.; Martemyanov, V.; Tarasenkov, V.; Aleshin, V.; Petelin, A.; Izhutov, A.; Tuzov, A.; Sazontov, S.; Ryazanov, D.; Gromov, M.; Afanasiev, V.; Zaytsev, M.; Chaikovskii, M.

2017-01-01

In order to carry out research in the field of possible existence of a sterile neutrino the laboratory based on SM-3 reactor (Dimitrovgrad, Russia) was created to search for oscillations of reactor antineutrino. The prototype of a multi-section neutrino detector with liquid scintillator volume of 350 l was installed in the middle of 2015. It is a moveable inside the passive shielding detector, which can be set at distance range from 6 to 11 meters from the reactor core. Measurements of antineutrino flux at such short distances from the reactor core are carried out with moveable detector for the first time. The measurements with full-scale detector with liquid scintillator volume of 3m3 (5x10 sections) was started only in June, 2016. The today available data is presented in the article.

Control method for prosthetic devices

NASA Technical Reports Server (NTRS)

Bozeman, Richard J., Jr. (Inventor)

1995-01-01

A control system and method for prosthetic devices is provided. The control system comprises a transducer for receiving movement from a body part for generating a sensing signal associated with that movement. The sensing signal is processed by a linearizer for linearizing the sensing signal to be a linear function of the magnitude of the distance moved by the body part. The linearized sensing signal is normalized to be a function of the entire range of body part movement from the no-shrug position of the moveable body part. The normalized signal is divided into a plurality of discrete command signals. The discrete command signals are used by typical converter devices which are in operational association with the prosthetic device. The converter device uses the discrete command signals for driving the moveable portions of the prosthetic device and its sub-prosthesis. The method for controlling a prosthetic device associated with the present invention comprises the steps of receiving the movement from the body part, generating a sensing signal in association with the movement of the body part, linearizing the sensing signal to be a linear function of the magnitude of the distance moved by the body part, normalizing the linear signal to be a function of the entire range of the body part movement, dividing the normalized signal into a plurality of discrete command signals, and implementing the plurality of discrete command signals for driving the respective moveable prosthesis device and its sub-prosthesis.

Measurement of body joint angles for physical therapy based on mean shift tracking using two low cost Kinect images.

PubMed

Chen, Y C; Lee, H J; Lin, K H

2015-08-01

Range of motion (ROM) is commonly used to assess a patient's joint function in physical therapy. Because motion capture systems are generally very expensive, physical therapists mostly use simple rulers to measure patients' joint angles in clinical diagnosis, which will suffer from low accuracy, low reliability, and subjective. In this study we used color and depth image feature from two sets of low-cost Microsoft Kinect to reconstruct 3D joint positions, and then calculate moveable joint angles to assess the ROM. A Gaussian background model is first used to segment the human body from the depth images. The 3D coordinates of the joints are reconstructed from both color and depth images. To track the location of joints throughout the sequence more precisely, we adopt the mean shift algorithm to find out the center of voxels upon the joints. The two sets of Kinect are placed three meters away from each other and facing to the subject. The joint moveable angles and the motion data are calculated from the position of joints frame by frame. To verify the results of our system, we take the results from a motion capture system called VICON as golden standard. Our 150 test results showed that the deviation of joint moveable angles between those obtained by VICON and our system is about 4 to 8 degree in six different upper limb exercises, which are acceptable in clinical environment.

EFFECTS OF MOVEABLE PLATFORM TRAINING IN PREVENTING SLIP-INDUCED FALLS IN OLDER ADULTS

PubMed Central

Parijat, Prakriti; Lockhart, Thurmon E

2011-01-01

Identifying effective interventions is vitalin preventing slip-induced fall accidents in older adults. The purpose of the current study was to evaluate the efficacy of moveable platform training in improving recovery reactions and reducing fall frequency in older adults. Twenty-four older adults were recruited and randomly assigned to two groups (training and control). Both groups underwent three sessions including baseline slip, training, and transfer of training on a slippery surface. Both groups experienced two slips on a slippery surface, one during the baseline and the other (after two weeks) during the transfer of training session. In the training session, the training group underwent twelve simulated slips using a moveable platform while the control group performed normal walking trials. Kinematic, kinetic, and EMG data were collected during all the sessions. Results indicated a reduced incidence of falls in the training group during the transfer of training trial as compared to the control group. The training group was able to transfer proactive and reactive control strategies learned during training to the second slip trial. The proactive adjustments include increased center-of-mass velocity and transitional acceleration after training. Reactive adjustments include reduction in muscle onset and time to peak activations of knee flexors and ankle plantarflexors, reduced ankle and knee coactivation, reduced slip displacement, and reduced time to peak knee flexion, trunk flexion, and hip flexion velocities. In general, the results indicated a beneficial effect of perturbation training in reducing slip severity and recovery kinematics in healthy older adults. PMID:22134467

Fat ViP MRI: Virtual Phantom Magnetic Resonance Imaging of water-fat systems.

PubMed

Salvati, Roberto; Hitti, Eric; Bellanger, Jean-Jacques; Saint-Jalmes, Hervé; Gambarota, Giulio

2016-06-01

Virtual Phantom Magnetic Resonance Imaging (ViP MRI) is a method to generate reference signals on MR images, using external radiofrequency (RF) signals. The aim of this study was to assess the feasibility of ViP MRI to generate complex-data images of phantoms mimicking water-fat systems. Various numerical phantoms with a given fat fraction, T2* and field map were designed. The k-space of numerical phantoms was converted into RF signals to generate virtual phantoms. MRI experiments were performed at 4.7T using a multi-gradient-echo sequence on virtual and physical phantoms. The data acquisition of virtual and physical phantoms was simultaneous. Decomposition of the water and fat signals was performed using a complex-based water-fat separation algorithm. Overall, a good agreement was observed between the fat fraction, T2* and phase map values of the virtual and numerical phantoms. In particular, fat fractions of 10.5±0.1 (vs 10% of the numerical phantom), 20.3±0.1 (vs 20%) and 30.4±0.1 (vs 30%) were obtained in virtual phantoms. The ViP MRI method allows for generating imaging phantoms that i) mimic water-fat systems and ii) can be analyzed with water-fat separation algorithms based on complex data. Copyright © 2016 Elsevier Inc. All rights reserved.

Design of a fused phantom for quantitative evaluation of brain metabolites and enhanced quality assurance testing for magnetic resonance imaging and spectroscopy.

PubMed

Song, Kyu-Ho; Kim, Sang-Young; Lee, Do-Wan; Jung, Jin-Young; Lee, Jung-Hoon; Baek, Hyeon-Man; Choe, Bo-Young

2015-11-30

Magnetic resonance imaging and spectroscopy (MRI-MRS) is a useful tool for the identification and evaluation of chemical changes in anatomical regions. Quality assurance (QA) is performed in either images or spectra using QA phantom. Therefore, consistent and uniform technical MRI-MRS QA is crucial. Here we developed an MRI-MRS fused phantom along with the inserts for metabolite quantification to simultaneously optimize QA parameters for both MRI and MRS. T1- and T2-weighted images were obtained and MRS was performed with point-resolved spectroscopy. Using the fused phantom, the results of measuring MRI factors were: geometric distortion, <2% and ± 2 mm; image intensity uniformity, 83.09 ± 1.33%; percent-signal ghosting, 0.025 ± 0.004; low-contrast object detectability, 27.85 ± 0.80. In addition, the signal-to-noise ratio of N-acetyl-aspartate was consistently high (42.00 ± 5.66). In previous studies, MR phantoms could not obtain information from both images and spectra in the MR scanner simultaneously. Here we designed and developed a phantom for accurate and consistent QA within the acceptance range. It is important to take into account variations in the QA value using the MRI-MRS phantom, when comparing to other clinical or research MR scanners. The MRI-MRS QA factors obtained simultaneously using the phantom can facilitate evaluation of both images and spectra, and provide guidelines for obtaining MRI and MRS QA factors simultaneously. Copyright © 2015 Elsevier B.V. All rights reserved.

Fabrication and characterization of a 3-D non-homogeneous tissue-like mouse phantom for optical imaging

NASA Astrophysics Data System (ADS)

Avtzi, Stella; Zacharopoulos, Athanasios; Psycharakis, Stylianos; Zacharakis, Giannis

2013-11-01

In vivo optical imaging of biological tissue not only requires the development of new theoretical models and experimental procedures, but also the design and construction of realistic tissue-mimicking phantoms. However, most of the phantoms available currently in literature or the market, have either simple geometrical shapes (cubes, slabs, cylinders) or when realistic in shape they use homogeneous approximations of the tissue or animal under investigation. The goal of this study is to develop a non-homogeneous realistic phantom that matches the anatomical geometry and optical characteristics of the mouse head in the visible and near-infrared spectral range. The fabrication of the phantom consisted of three stages. Initially, anatomical information extracted from either mouse head atlases or structural imaging modalities (MRI, XCT) was used to design a digital phantom comprising of the three main layers of the mouse head; the brain, skull and skin. Based on that, initial prototypes were manufactured by using accurate 3D printing, allowing complex objects to be built layer by layer with sub-millimeter resolution. During the second stage the fabrication of individual molds was performed by embedding the prototypes into a rubber-like silicone mixture. In the final stage the detailed phantom was constructed by loading the molds with epoxy resin of controlled optical properties. The optical properties of the resin were regulated by using appropriate quantities of India ink and intralipid. The final phantom consisted of 3 layers, each one with different absorption and scattering coefficient (μa,μs) to simulate the region of the mouse brain, skull and skin.

Operating characteristics of tube-current-modulation techniques when scanning simple-shaped phantoms

NASA Astrophysics Data System (ADS)

Matsubara, Kosuke; Koshida, Kichiro; Lin, Pei-Jan Paul; Fukuda, Atsushi

2015-07-01

Our objective was to investigate the operating characteristics of tube current modulation (TCM) in computed tomography (CT) when scanning two types of simple-shaped phantoms. A tissueequivalent elliptical phantom and a homogeneous cylindrical step phantom comprising 16-, 24-, and 32-cm-diameter polymethyl methacrylate (PMMA) phantoms were scanned by using an automatic exposure control system with longitudinal (z-) and angular-longitudinal (xyz-) TCM and with a fixed tube current. The axial dose distribution throughout the elliptical phantom and the longitudinal dose distribution at the center of the cylindrical step phantom were measured by using a solid-state detector. Image noise was quantitatively measured at eight regions in the elliptical phantom and at 90 central regions in contiguous images over the full z extent of the cylindrical step phantom. The mean absorbed doses and the standard deviations in the elliptical phantom with z- and xyz-TCM were 12.3' 3.7 and 11.3' 3.5 mGy, respectively. When TCM was activated, some differences were observed in the absorbed doses of the left and the right measurement points. The average image noises in Hounsfield units (HU) and the standard deviations were 15.2' 2.4 and 15.9' 2.4 HU when using z- and xyz-TCM, respectively. With respect to the cylindrical step phantom under z-TCM, there were sudden decreases followed by increases in image noise at the interfaces with the 24- and 16-cm-diameter phantoms. The image noise of the 24-cm-diameter phantom was, relatively speaking, higher than those of the 16- and 32-cm-diameter phantoms. The simple-shaped phantoms used in this study can be employed to investigate the operating characteristics of automatic exposure control systems when specialized phantoms designed for that purpose are not available.

MO-B-BRD-03: Principles, Pitfalls and Techniques of 3D Printing for Bolus and Compensators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baker, J.

This session is designed so that the learning objectives are practical. The intent is that the attendee may take home an understanding of not just the technology, but also the logistical steps necessary to execute these 3D printing techniques in the clinic. Four practical 3D printing topics will be discussed: (i) Creating bolus and compensators for photon machines; (ii) tools for proton therapy; (iii) clinical applications in imaging; (iv) custom phantom design for clinic and research use. The use of 3D printers within the radiation oncology setting is proving to be a useful tool for creating patient specific bolus andmore » compensators with the added benefit of cost savings. Creating the proper protocol is essential to ensuring that the desired effect is achieved and modeled in the treatment planning system. The critical choice of printer material (since it determines the interaction with the radiation) will be discussed. Selection of 3D printer type, design methods, verification of dose calculation, and the printing process will be detailed to give the basis for establishing your own protocol for electron and photon fields. A practical discussion of likely obstacles that may be encountered will be included. The diversity of systems and techniques in proton facilities leads to different facilities having very different requirements for beam modifying hardware and quality assurance devices. Many departments find the need to design and fabricate facility-specific equipment, making 3D printing an attractive technology. 3D printer applications in proton therapy will be discussed, including beam filters and compensators, and the design of proton therapy specific quality assurance tools. Quality control specific to 3D printing in proton therapy will be addressed. Advantages and disadvantages of different printing technology for these applications will also be discussed. 3D printing applications using high-resolution radiology-based imaging data will be presented. This data is used to 3D print individualized physical models of patient’s unique anatomy for aid in planning complex and challenging surgical procedures. Methods, techniques and imaging requirements for 3D printing anatomic models from imaging data will be discussed. Specific applications currently being used in the radiology clinic will be detailed. Standardized phantoms for radiation therapy are abundant. However, custom phantom designs can be advantageous for both clinical tasks and research. 3D printing is a useful method of custom fabrication that allows one to construct custom objects relatively quickly. Possibilities for custom radiotherapy phantoms range from 3D printing a hollow shell and filling the shell with tissue equivalent materials to fully printing the entire phantom with materials that are tissue equivalent as well as suitable for 3D printing. A range of materials available for use in radiotherapy phantoms and in the case of phantoms for dosimetric measurements, this choice is critical. The necessary steps required will be discussed including: modalities of 3D model generation, 3D model requirements for 3D printing, generation of machine instructions from the 3D model, and 3D printing techniques, choice of phantoms material, and troubleshooting techniques for each step in the process. Case examples of 3D printed phantoms will be shown. Learning Objectives: Understand the types of 3D modeling software required to design your device, the file formats required for data transfer from design software to 3D printer, and general troubleshooting techniques for each step of the process. Learn the differences between materials and design for photons vs. electrons vs. protons. Understand the importance of material choice and design geometries for your custom phantoms. Learn specific steps of quality assurance and quality control for 3D printed beam filters and compensators for proton therapy. Learn of special 3D printing applications for imaging. Cunha: Research support from Phillips Healthcare.« less

MO-B-BRD-00: Clinical Applications of 3D Printing

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

This session is designed so that the learning objectives are practical. The intent is that the attendee may take home an understanding of not just the technology, but also the logistical steps necessary to execute these 3D printing techniques in the clinic. Four practical 3D printing topics will be discussed: (i) Creating bolus and compensators for photon machines; (ii) tools for proton therapy; (iii) clinical applications in imaging; (iv) custom phantom design for clinic and research use. The use of 3D printers within the radiation oncology setting is proving to be a useful tool for creating patient specific bolus andmore » compensators with the added benefit of cost savings. Creating the proper protocol is essential to ensuring that the desired effect is achieved and modeled in the treatment planning system. The critical choice of printer material (since it determines the interaction with the radiation) will be discussed. Selection of 3D printer type, design methods, verification of dose calculation, and the printing process will be detailed to give the basis for establishing your own protocol for electron and photon fields. A practical discussion of likely obstacles that may be encountered will be included. The diversity of systems and techniques in proton facilities leads to different facilities having very different requirements for beam modifying hardware and quality assurance devices. Many departments find the need to design and fabricate facility-specific equipment, making 3D printing an attractive technology. 3D printer applications in proton therapy will be discussed, including beam filters and compensators, and the design of proton therapy specific quality assurance tools. Quality control specific to 3D printing in proton therapy will be addressed. Advantages and disadvantages of different printing technology for these applications will also be discussed. 3D printing applications using high-resolution radiology-based imaging data will be presented. This data is used to 3D print individualized physical models of patient’s unique anatomy for aid in planning complex and challenging surgical procedures. Methods, techniques and imaging requirements for 3D printing anatomic models from imaging data will be discussed. Specific applications currently being used in the radiology clinic will be detailed. Standardized phantoms for radiation therapy are abundant. However, custom phantom designs can be advantageous for both clinical tasks and research. 3D printing is a useful method of custom fabrication that allows one to construct custom objects relatively quickly. Possibilities for custom radiotherapy phantoms range from 3D printing a hollow shell and filling the shell with tissue equivalent materials to fully printing the entire phantom with materials that are tissue equivalent as well as suitable for 3D printing. A range of materials available for use in radiotherapy phantoms and in the case of phantoms for dosimetric measurements, this choice is critical. The necessary steps required will be discussed including: modalities of 3D model generation, 3D model requirements for 3D printing, generation of machine instructions from the 3D model, and 3D printing techniques, choice of phantoms material, and troubleshooting techniques for each step in the process. Case examples of 3D printed phantoms will be shown. Learning Objectives: Understand the types of 3D modeling software required to design your device, the file formats required for data transfer from design software to 3D printer, and general troubleshooting techniques for each step of the process. Learn the differences between materials and design for photons vs. electrons vs. protons. Understand the importance of material choice and design geometries for your custom phantoms. Learn specific steps of quality assurance and quality control for 3D printed beam filters and compensators for proton therapy. Learn of special 3D printing applications for imaging. Cunha: Research support from Phillips Healthcare.« less

MO-B-BRD-04: Sterilization for 3D Printed Brachytherapy Applicators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cunha, J.

This session is designed so that the learning objectives are practical. The intent is that the attendee may take home an understanding of not just the technology, but also the logistical steps necessary to execute these 3D printing techniques in the clinic. Four practical 3D printing topics will be discussed: (i) Creating bolus and compensators for photon machines; (ii) tools for proton therapy; (iii) clinical applications in imaging; (iv) custom phantom design for clinic and research use. The use of 3D printers within the radiation oncology setting is proving to be a useful tool for creating patient specific bolus andmore » compensators with the added benefit of cost savings. Creating the proper protocol is essential to ensuring that the desired effect is achieved and modeled in the treatment planning system. The critical choice of printer material (since it determines the interaction with the radiation) will be discussed. Selection of 3D printer type, design methods, verification of dose calculation, and the printing process will be detailed to give the basis for establishing your own protocol for electron and photon fields. A practical discussion of likely obstacles that may be encountered will be included. The diversity of systems and techniques in proton facilities leads to different facilities having very different requirements for beam modifying hardware and quality assurance devices. Many departments find the need to design and fabricate facility-specific equipment, making 3D printing an attractive technology. 3D printer applications in proton therapy will be discussed, including beam filters and compensators, and the design of proton therapy specific quality assurance tools. Quality control specific to 3D printing in proton therapy will be addressed. Advantages and disadvantages of different printing technology for these applications will also be discussed. 3D printing applications using high-resolution radiology-based imaging data will be presented. This data is used to 3D print individualized physical models of patient’s unique anatomy for aid in planning complex and challenging surgical procedures. Methods, techniques and imaging requirements for 3D printing anatomic models from imaging data will be discussed. Specific applications currently being used in the radiology clinic will be detailed. Standardized phantoms for radiation therapy are abundant. However, custom phantom designs can be advantageous for both clinical tasks and research. 3D printing is a useful method of custom fabrication that allows one to construct custom objects relatively quickly. Possibilities for custom radiotherapy phantoms range from 3D printing a hollow shell and filling the shell with tissue equivalent materials to fully printing the entire phantom with materials that are tissue equivalent as well as suitable for 3D printing. A range of materials available for use in radiotherapy phantoms and in the case of phantoms for dosimetric measurements, this choice is critical. The necessary steps required will be discussed including: modalities of 3D model generation, 3D model requirements for 3D printing, generation of machine instructions from the 3D model, and 3D printing techniques, choice of phantoms material, and troubleshooting techniques for each step in the process. Case examples of 3D printed phantoms will be shown. Learning Objectives: Understand the types of 3D modeling software required to design your device, the file formats required for data transfer from design software to 3D printer, and general troubleshooting techniques for each step of the process. Learn the differences between materials and design for photons vs. electrons vs. protons. Understand the importance of material choice and design geometries for your custom phantoms. Learn specific steps of quality assurance and quality control for 3D printed beam filters and compensators for proton therapy. Learn of special 3D printing applications for imaging. Cunha: Research support from Phillips Healthcare.« less

MO-B-BRD-02: 3D Printing in the Clinic

DOE Office of Scientific and Technical Information (OSTI.GOV)

Remmes, N.

This session is designed so that the learning objectives are practical. The intent is that the attendee may take home an understanding of not just the technology, but also the logistical steps necessary to execute these 3D printing techniques in the clinic. Four practical 3D printing topics will be discussed: (i) Creating bolus and compensators for photon machines; (ii) tools for proton therapy; (iii) clinical applications in imaging; (iv) custom phantom design for clinic and research use. The use of 3D printers within the radiation oncology setting is proving to be a useful tool for creating patient specific bolus andmore » compensators with the added benefit of cost savings. Creating the proper protocol is essential to ensuring that the desired effect is achieved and modeled in the treatment planning system. The critical choice of printer material (since it determines the interaction with the radiation) will be discussed. Selection of 3D printer type, design methods, verification of dose calculation, and the printing process will be detailed to give the basis for establishing your own protocol for electron and photon fields. A practical discussion of likely obstacles that may be encountered will be included. The diversity of systems and techniques in proton facilities leads to different facilities having very different requirements for beam modifying hardware and quality assurance devices. Many departments find the need to design and fabricate facility-specific equipment, making 3D printing an attractive technology. 3D printer applications in proton therapy will be discussed, including beam filters and compensators, and the design of proton therapy specific quality assurance tools. Quality control specific to 3D printing in proton therapy will be addressed. Advantages and disadvantages of different printing technology for these applications will also be discussed. 3D printing applications using high-resolution radiology-based imaging data will be presented. This data is used to 3D print individualized physical models of patient’s unique anatomy for aid in planning complex and challenging surgical procedures. Methods, techniques and imaging requirements for 3D printing anatomic models from imaging data will be discussed. Specific applications currently being used in the radiology clinic will be detailed. Standardized phantoms for radiation therapy are abundant. However, custom phantom designs can be advantageous for both clinical tasks and research. 3D printing is a useful method of custom fabrication that allows one to construct custom objects relatively quickly. Possibilities for custom radiotherapy phantoms range from 3D printing a hollow shell and filling the shell with tissue equivalent materials to fully printing the entire phantom with materials that are tissue equivalent as well as suitable for 3D printing. A range of materials available for use in radiotherapy phantoms and in the case of phantoms for dosimetric measurements, this choice is critical. The necessary steps required will be discussed including: modalities of 3D model generation, 3D model requirements for 3D printing, generation of machine instructions from the 3D model, and 3D printing techniques, choice of phantoms material, and troubleshooting techniques for each step in the process. Case examples of 3D printed phantoms will be shown. Learning Objectives: Understand the types of 3D modeling software required to design your device, the file formats required for data transfer from design software to 3D printer, and general troubleshooting techniques for each step of the process. Learn the differences between materials and design for photons vs. electrons vs. protons. Understand the importance of material choice and design geometries for your custom phantoms. Learn specific steps of quality assurance and quality control for 3D printed beam filters and compensators for proton therapy. Learn of special 3D printing applications for imaging. Cunha: Research support from Phillips Healthcare.« less

SU-E-T-234: Daily Quality Assurance for a Six Degrees of Freedom Couch Using a Novel Phantom

DOE Office of Scientific and Technical Information (OSTI.GOV)

Woods, K; Woollard, J; Ayan, A

2015-06-15

Purpose: To test the accuracy and reproducibility of both translational and rotational movements for a couch with six degrees of freedom (6DoF) using a novel phantom design Methods: An end-to-end test was carried out using two different phantoms. A 6 cm3 cube with a central fiducial BB (WL-QA Sun Nuclear) and a custom fabricated rectangular prism (31 cm x 8 cm x 8 cm), placed on a baseplate with known angular offsets for pitch, roll and yaw with a central fiducial BB and unique surface structures for registration purposes, were used. The end-to-end test included an initial CT simulation formore » a reference study, setup to an offset mark on each phantom, registration of the reference CT to the acquired cone-beam CT, and final Winston-Lutz delivery at four cardinal gantry angles. Results for both translational and rotational movements were recorded and compared for both phantoms. Results: Translational and rotational measurements were performed with a PerfectPitch (Varian) couch for 10 trials for both phantoms. Distinct translational shifts were [−5.372±0.384mm, −10.183±0.137mm, 14.028±0.155mm] for the cube and [7.520±0.159mm, −9.117±0.101mm, 16.273±0.115mm] for the prototype phantom for lateral, longitudinal, and vertical shifts, respectively. Distinct rotational adjustments were [1.121±0.102o, −1.067±0.235o, −2.662±0.380o] for the cube and [2.534±0.059o, 1.994±0.025o, 2.094±0.076o] for the prototype for pitch, roll, and yaw, respectively. Winston-Lutz test results performed after 6DoF couch correction from each cardinal gantry angle ranged from 0.26–0.72mm for the cube and 0.55–0.86mm for the prototype. Conclusion: The prototype phantom is more precise for both translational and rotational adjustments compared to a commercial phantom. The design of the prototype phantom allows for a more discernible visual confirmation of correct translational and rotational adjustments with the prototype phantom. Winston-Lutz results are more accurate for the commercial phantom but are still within tolerance for the prototype phantom.« less

Tissue Equivalent Phantom Design for Characterization of a Coherent Scatter X-ray Imaging System

NASA Astrophysics Data System (ADS)

Albanese, Kathryn Elizabeth

Scatter in medical imaging is typically cast off as image-related noise that detracts from meaningful diagnosis. It is therefore typically rejected or removed from medical images. However, it has been found that every material, including cancerous tissue, has a unique X-ray coherent scatter signature that can be used to identify the material or tissue. Such scatter-based tissue-identification provides the advantage of locating and identifying particular materials over conventional anatomical imaging through X-ray radiography. A coded aperture X-ray coherent scatter spectral imaging system has been developed in our group to classify different tissue types based on their unique scatter signatures. Previous experiments using our prototype have demonstrated that the depth-resolved coherent scatter spectral imaging system (CACSSI) can discriminate healthy and cancerous tissue present in the path of a non-destructive x-ray beam. A key to the successful optimization of CACSSI as a clinical imaging method is to obtain anatomically accurate phantoms of the human body. This thesis describes the development and fabrication of 3D printed anatomical scatter phantoms of the breast and lung. The purpose of this work is to accurately model different breast geometries using a tissue equivalent phantom, and to classify these tissues in a coherent x-ray scatter imaging system. Tissue-equivalent anatomical phantoms were designed to assess the capability of the CACSSI system to classify different types of breast tissue (adipose, fibroglandular, malignant). These phantoms were 3D printed based on DICOM data obtained from CT scans of prone breasts. The phantoms were tested through comparison of measured scatter signatures with those of adipose and fibroglandular tissue from literature. Tumors in the phantom were modeled using a variety of biological tissue including actual surgically excised benign and malignant tissue specimens. Lung based phantoms have also been printed for future testing. Our imaging system has been able to define the location and composition of the various materials in the phantom. These phantoms were used to characterize the CACSSI system in terms of beam width and imaging technique. The result of this work showed accurate modeling and characterization of the phantoms through comparison of the tissue-equivalent form factors to those from literature. The physical construction of the phantoms, based on actual patient anatomy, was validated using mammography and computed tomography to visually compare the clinical images to those of actual patient anatomy.

Astronaut David Wolf participates in training for contingency EVA in WETF

NASA Image and Video Library

1993-04-03

S93-31706 (3 April 1993) --- With the aid of technicians and training staffers astronaut David A. Wolf prepares to participate in training for contingency Extravehicular Activity (EVA) for the STS-58 mission. Sharing a moveable platform with Wolf was astronaut Shannon W. Lucid (out of frame). For simulation purposes, the two mission specialists were about to be submerged to a point of neutral buoyancy in the Johnson Space Center's (JSC) Weightless Environment Training Facility (WET-F). Though the Spacelab Life Sciences (SLS-2) mission does not include a planned EVA, all crews designate members to learn proper procedures to perform outside the spacecraft in the event of failure of remote means to accomplish those tasks.

Astronaut Shannon Lucid in training for contingency EVA for STS-58 in WETF

NASA Image and Video Library

1993-04-03

S93-31697 (3 April 1993) --- Astronaut Shannon W. Lucid participates in training for contingency Extravehicular Activity (EVA) for the STS-58 mission. Behind Lucid, sharing a moveable platform with her, is astronaut David A. Wolf (out of frame). For simulation purposes, the two mission specialists were about to be submerged to a point of neutral buoyancy in the Johnson Space Center's (JSC) Weightless Environment Training Facility (WET-F). Though the Spacelab Life Sciences (SLS-2) mission does not include a planned EVA, all crews designate members to learn proper procedures to perform outside the spacecraft in the event of failure of remote means to accomplish those tasks.

KSC-07pd2868

NASA Image and Video Library

2007-10-01

KENNEDY SPACE CENTER, FLA. -- In the Space Station Processing Facility at NASA's Kennedy Space Center, the starboard arm of the Special Purpose Dexterous Manipulator, known as Dextre, is lowered toward the base for installation. Dextre is a sophisticated dual-armed robot, which is part of Canada's contribution to the International Space Station (ISS). Along with Canadarm2, whose technical name is the Space Station Remote Manipulator System, and a moveable work platform called the Mobile Base System, these three elements form a robotic system called the Mobile Servicing System, or MSS. The three components have been designed to work together or independently. Dextre is part of the payload scheduled on mission STS-123, targeted to launch Feb. 14. Photo credit: NASA/George Shelton

Aerodynamic flight control to increase payload capability of future launch vehicles

NASA Technical Reports Server (NTRS)

Cochran, John E., Jr.

1995-01-01

The development of new launch vehicles will require that designers use innovative approaches to achieve greater performance in terms of pay load capability. The objective of the work performed under this delivery order was to provide technical assistance to the Contract Officer's Technical Representative (COTR) in the development of ideas and concepts for increasing the payload capability of launch vehicles by incorporating aerodynamic controls. Although aerodynamic controls, such as moveable fins, are currently used on relatively small missiles, the evolution of large launch vehicles has been moving away from aerodynamic control. The COTR reasoned that a closer investigation of the use of aerodynamic controls on large vehicles was warranted.

Simulation tools for two-dimensional experiments in x-ray computed tomography using the FORBILD head phantom

PubMed Central

Yu, Zhicong; Noo, Frédéric; Dennerlein, Frank; Wunderlich, Adam; Lauritsch, Günter; Hornegger, Joachim

2012-01-01

Mathematical phantoms are essential for the development and early-stage evaluation of image reconstruction algorithms in x-ray computed tomography (CT). This note offers tools for computer simulations using a two-dimensional (2D) phantom that models the central axial slice through the FORBILD head phantom. Introduced in 1999, in response to a need for a more robust test, the FORBILD head phantom is now seen by many as the gold standard. However, the simple Shepp-Logan phantom is still heavily used by researchers working on 2D image reconstruction. Universal acceptance of the FORBILD head phantom may have been prevented by its significantly-higher complexity: software that allows computer simulations with the Shepp-Logan phantom is not readily applicable to the FORBILD head phantom. The tools offered here address this problem. They are designed for use with Matlab®, as well as open-source variants, such as FreeMat and Octave, which are all widely used in both academia and industry. To get started, the interested user can simply copy and paste the codes from this PDF document into Matlab® M-files. PMID:22713335

Simulation tools for two-dimensional experiments in x-ray computed tomography using the FORBILD head phantom.

PubMed

Yu, Zhicong; Noo, Frédéric; Dennerlein, Frank; Wunderlich, Adam; Lauritsch, Günter; Hornegger, Joachim

2012-07-07

Mathematical phantoms are essential for the development and early stage evaluation of image reconstruction algorithms in x-ray computed tomography (CT). This note offers tools for computer simulations using a two-dimensional (2D) phantom that models the central axial slice through the FORBILD head phantom. Introduced in 1999, in response to a need for a more robust test, the FORBILD head phantom is now seen by many as the gold standard. However, the simple Shepp-Logan phantom is still heavily used by researchers working on 2D image reconstruction. Universal acceptance of the FORBILD head phantom may have been prevented by its significantly higher complexity: software that allows computer simulations with the Shepp-Logan phantom is not readily applicable to the FORBILD head phantom. The tools offered here address this problem. They are designed for use with Matlab®, as well as open-source variants, such as FreeMat and Octave, which are all widely used in both academia and industry. To get started, the interested user can simply copy and paste the codes from this PDF document into Matlab® M-files.

Regulatory perspectives and research activities at the FDA on the use of phantoms with in vivo diagnostic devices

NASA Astrophysics Data System (ADS)

Agrawal, Anant; Gavrielides, Marios A.; Weininger, Sandy; Chakrabarti, Kish; Pfefer, Joshua

2008-02-01

For a number of years, phantoms have been used to optimize device parameters and validate performance in the primary medical imaging modalities (CT, MRI, PET/SPECT, ultrasound). Furthermore, the FDA under the Mammography Quality Standards Act (MQSA) requires image quality evaluation of mammography systems using FDA-approved phantoms. The oldest quantitative optical diagnostic technology, pulse oximetry, also benefits from the use of active phantoms known as patient simulators to validate certain performance characteristics under different clinically-relevant conditions. As such, guidance provided by the FDA to its staff and to industry on the contents of pre-market notification and approval submissions includes suggestions on how to incorporate the appropriate phantoms in establishing device effectiveness. Research at the FDA supports regulatory statements on the use of phantoms by investigating how phantoms can be designed, characterized, and utilized to determine critical device performance characteristics. These examples provide a model for how novel techniques in the rapidly growing field of optical diagnostics can use phantoms during pre- and post-market regulatory testing.

Evaluation of a pointwise microcirculation assessment method using liquid and multilayered tissue simulating phantoms

NASA Astrophysics Data System (ADS)

Fredriksson, Ingemar; Saager, Rolf B.; Durkin, Anthony J.; Strömberg, Tomas

2017-11-01

A fiber-optic probe-based instrument, designed for assessment of parameters related to microcirculation, red blood cell tissue fraction (fRBC), oxygen saturation (S), and speed resolved perfusion, has been evaluated using state-of-the-art tissue phantoms. The probe integrates diffuse reflectance spectroscopy (DRS) at two source-detector separations and laser Doppler flowmetry, using an inverse Monte Carlo method for identifying the parameters of a multilayered tissue model. Here, we characterize the accuracy of the DRS aspect of the instrument using (1) liquid blood phantoms containing yeast and (2) epidermis-dermis mimicking solid-layered phantoms fabricated from polydimethylsiloxane, titanium oxide, hemoglobin, and coffee. The root-mean-square (RMS) deviations for fRBC for the two liquid phantoms were 11% and 5.3%, respectively, and 11% for the solid phantoms with highest hemoglobin signatures. The RMS deviation for S was 5.2% and 2.9%, respectively, for the liquid phantoms, and 2.9% for the solid phantoms. RMS deviation for the reduced scattering coefficient (μs‧), for the solid phantoms was 15% (475 to 850 nm). For the liquid phantoms, the RMS deviation in average vessel diameter (D) was 1 μm. In conclusion, the skin microcirculation parameters fRBC and S, as well as, μs‧ and D are estimated with reasonable accuracy.

Advanced 3D mesh manipulation in stereolithographic files and post-print processing for the manufacturing of patient-specific vascular flow phantoms

NASA Astrophysics Data System (ADS)

O'Hara, Ryan P.; Chand, Arpita; Vidiyala, Sowmya; Arechavala, Stacie M.; Mitsouras, Dimitrios; Rudin, Stephen; Ionita, Ciprian N.

2016-03-01

Complex vascular anatomies can cause the failure of image-guided endovascular procedures. 3D printed patient-specific vascular phantoms provide clinicians and medical device companies the ability to preemptively plan surgical treatments, test the likelihood of device success, and determine potential operative setbacks. This research aims to present advanced mesh manipulation techniques of stereolithographic (STL) files segmented from medical imaging and post-print surface optimization to match physiological vascular flow resistance. For phantom design, we developed three mesh manipulation techniques. The first method allows outlet 3D mesh manipulations to merge superfluous vessels into a single junction, decreasing the number of flow outlets and making it feasible to include smaller vessels. Next we introduced Boolean operations to eliminate the need to manually merge mesh layers and eliminate errors of mesh self-intersections that previously occurred. Finally we optimize support addition to preserve the patient anatomical geometry. For post-print surface optimization, we investigated various solutions and methods to remove support material and smooth the inner vessel surface. Solutions of chloroform, alcohol and sodium hydroxide were used to process various phantoms and hydraulic resistance was measured and compared with values reported in literature. The newly mesh manipulation methods decrease the phantom design time by 30 - 80% and allow for rapid development of accurate vascular models. We have created 3D printed vascular models with vessel diameters less than 0.5 mm. The methods presented in this work could lead to shorter design time for patient specific phantoms and better physiological simulations.

Design and clinical use of a rotational phantom for dosimetric verification of IMRT/VMAT treatments.

PubMed

Grams, Michael P; de Los Santos, Luis E Fong

2018-06-01

To describe the design and clinical use of a rotational phantom for dosimetric verification of IMRT/VMAT treatment plans using radiochromic film. A solid water cylindrical phantom was designed with separable upper and lower halves and rests on plastic bearings allowing for 360° rotation about its central axis. The phantom accommodates a half sheet of radiochromic film, and by rotating the cylinder, the film can be placed in any plane between coronal and sagittal. Calculated dose planes coinciding with rotated film measurements are exported by rotating the CT image and dose distribution within the treatment planning system. The process is illustrated with 2 rotated film measurements of an SRS treatment plan involving 4 separate targets. Additionally, 276 patient specific QA measurements were obtained with the phantom and analyzed with a 2%/2 mm gamma criterion. The average 2%/2 mm gamma passing rate for all 276 plans was 99.3%. Seventy-two of the 276 plans were measured with the plane of the film rotated between the coronal and sagittal planes and had an average passing rate of 99.4%. The rotational phantom allows for accurate film measurements in any plane. With this technique, regions of a dose distribution which might otherwise require multiple sagittal or coronal measurements can be verified with as few as a single measurement. This increases efficiency and, in combination with the high spatial resolution inherent to film dosimetry, makes the rotational technique an attractive option for patient-specific QA. Copyright © 2018 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Advanced 3D Mesh Manipulation in Stereolithographic Files and Post-Print Processing for the Manufacturing of Patient-Specific Vascular Flow Phantoms.

PubMed

O'Hara, Ryan P; Chand, Arpita; Vidiyala, Sowmya; Arechavala, Stacie M; Mitsouras, Dimitrios; Rudin, Stephen; Ionita, Ciprian N

2016-02-27

Complex vascular anatomies can cause the failure of image-guided endovascular procedures. 3D printed patient-specific vascular phantoms provide clinicians and medical device companies the ability to preemptively plan surgical treatments, test the likelihood of device success, and determine potential operative setbacks. This research aims to present advanced mesh manipulation techniques of stereolithographic (STL) files segmented from medical imaging and post-print surface optimization to match physiological vascular flow resistance. For phantom design, we developed three mesh manipulation techniques. The first method allows outlet 3D mesh manipulations to merge superfluous vessels into a single junction, decreasing the number of flow outlets and making it feasible to include smaller vessels. Next we introduced Boolean operations to eliminate the need to manually merge mesh layers and eliminate errors of mesh self-intersections that previously occurred. Finally we optimize support addition to preserve the patient anatomical geometry. For post-print surface optimization, we investigated various solutions and methods to remove support material and smooth the inner vessel surface. Solutions of chloroform, alcohol and sodium hydroxide were used to process various phantoms and hydraulic resistance was measured and compared with values reported in literature. The newly mesh manipulation methods decrease the phantom design time by 30 - 80% and allow for rapid development of accurate vascular models. We have created 3D printed vascular models with vessel diameters less than 0.5 mm. The methods presented in this work could lead to shorter design time for patient specific phantoms and better physiological simulations.

Advanced 3D Mesh Manipulation in Stereolithographic Files and Post-Print Processing for the Manufacturing of Patient-Specific Vascular Flow Phantoms

PubMed Central

O’Hara, Ryan P.; Chand, Arpita; Vidiyala, Sowmya; Arechavala, Stacie M.; Mitsouras, Dimitrios; Rudin, Stephen; Ionita, Ciprian N.

2017-01-01

Complex vascular anatomies can cause the failure of image-guided endovascular procedures. 3D printed patient-specific vascular phantoms provide clinicians and medical device companies the ability to preemptively plan surgical treatments, test the likelihood of device success, and determine potential operative setbacks. This research aims to present advanced mesh manipulation techniques of stereolithographic (STL) files segmented from medical imaging and post-print surface optimization to match physiological vascular flow resistance. For phantom design, we developed three mesh manipulation techniques. The first method allows outlet 3D mesh manipulations to merge superfluous vessels into a single junction, decreasing the number of flow outlets and making it feasible to include smaller vessels. Next we introduced Boolean operations to eliminate the need to manually merge mesh layers and eliminate errors of mesh self-intersections that previously occurred. Finally we optimize support addition to preserve the patient anatomical geometry. For post-print surface optimization, we investigated various solutions and methods to remove support material and smooth the inner vessel surface. Solutions of chloroform, alcohol and sodium hydroxide were used to process various phantoms and hydraulic resistance was measured and compared with values reported in literature. The newly mesh manipulation methods decrease the phantom design time by 30 – 80% and allow for rapid development of accurate vascular models. We have created 3D printed vascular models with vessel diameters less than 0.5 mm. The methods presented in this work could lead to shorter design time for patient specific phantoms and better physiological simulations. PMID:28649165

Saturation measurement accuracy in clinical near-infrared cerebral oximeters with a 3D-printed channel array phantom

NASA Astrophysics Data System (ADS)

Afshari, Ali; Ghassemi, Pejhman; Halprin, Molly; Lin, Jonathan; Weininger, Sandy; Gandjbakhche, Amir H.; Wang, Jianting; Pfefer, Joshua

2018-02-01

Clinical cerebral oximeters based on near-infrared spectroscopy (NIRS) are a commonly used, non-invasive tool for intraoperative monitoring of hemoglobin saturation. Research to verify performance of cerebral oximeters in human subject trials has shown differences between commercially available devices. Test methods based on tissue-simulating phantoms have been proposed to augment clinical findings. While prior studies have focused on liquid phantoms, this work is aimed at developing methods based on solid polymer phantoms that are stable. Specifically, we have designed and fabricated a neonatal/pediatric head mimicking layered phantoms based on a 3D-printed cerebral matrix incorporating an array of vessel-simulating linear channels. Superficial layers incorporating homogeneous molded polydimethylsiloxane (PDMS) slabs were fabricated to represent CSF, scalp and skull regions. The cerebral matrix was filled with bovine blood desaturated with sodium dithionite to achieve oxygenation levels across the 40-90% range. Measurements were performed with a commercially available cerebral oximeter using two probes with different illumination-collection geometries, as designed for neonatal and pediatric patients. Reference measurements of samples were performed with a CO-oximeter before injection and after extraction. Results from applied cerebral oximeters indicate a strong sensitivity to the thickness of the superficial layer of the phantom. Better correlation with the reference CO-oximeter results were obtained in the superficial layer thickness of 0.8-2.5 mm range. Channel array phantoms with modular superficial layers represent a promising approach for performance testing of NIRS-based cerebral oximeters.

An alternate design for the Defrise phantom to quantify resolution in digital breast tomosynthesis

NASA Astrophysics Data System (ADS)

Acciavatti, Raymond J.; Mannherz, William; Nolan, Margaret; Maidment, Andrew D. A.

2017-03-01

Our previous work analyzed the Defrise phantom as a test object for evaluating image quality in digital breast tomosynthesis (DBT). The phantom is assembled from multiple plastic plates, which are arranged to form a square wave. In our previous work, there was no explicit analysis of how image quality varies with the thickness of the plates. To investigate this concept, a modified design of the phantom is now considered. For this purpose, each rectangular plate was laser-cut at an angle, creating a slope along which thickness varies continuously. The phantom was imaged using a clinical DBT system, and the relative modulation of the plastic-air separations was calculated in the reconstruction. In addition, a theoretical model was developed to determine whether modulation can be optimized by modifying the x-ray tube trajectory. It is demonstrated that modulation is dependent on the orientation of the frequency. Modulation is within detectable limits over a broad range of phantom thicknesses if frequency is parallel with the tube travel direction. Conversely, there is marked loss of modulation if frequency is oriented along the posteroanterior direction. In particular, as distance from the chest wall increases, there is a smaller range of thicknesses over which modulation is within detectable limits. Theoretical modeling suggests that this anisotropy is minimized by introducing tube motion along the posteroanterior direction. In conclusion, this paper demonstrates that the Defrise phantom is a tool for analyzing the limits of resolution in DBT systems.

SU-F-BRE-08: Feasibility of 3D Printed Patient Specific Phantoms for IMRT/IGRT QA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ehler, E; Higgins, P; Dusenbery, K

Purpose: Test the feasibility of 3D printed, per-patient phantoms for IMRT QA to analyze the treatment delivery quality within the patient geometry. Methods: Using the head and neck region of an anthropomorphic phantom as a substitute for an actual patient, a soft-tissue equivalent model was constructed with the use of a 3D printer. A nine-field IMRT plan was constructed and dose verification measurements were performed for the 3D printed phantom. During the delivery of the IMRT QA on to the 3D printed phantom, the same patient positioning indexing system was used on the phantom and image guidance (cone beam CT)more » was used to localize the phantom, serving as a test of the IGRT system as well. The 3D printed phantom was designed to accommodate four radiochromic film planes (two axial, one coronal and one sagittal) and an ionization chamber measurement. As a frame of comparison, the IMRT QA was also performed on traditional phantoms. Dosimetric tolerance levels such as 3mm / 3% Gamma Index as well as 3% and 5% dose difference were considered. All detector systems were calibrated against a NIST traceable ionization chamber. Results: Comparison of results 3D printed patient phantom with the standard IMRT QA systems showed similar passing rates for the 3D printed phantom and the standard phantoms. However, the locations of the failing regions did not necessarily correlate. The 3D printed phantom was localized within 1 mm and 1° using on-board cone beam CT. Conclusion: A custom phantom was created using a 3D printer. It was determined that the use of patient specific phantoms to perform dosimetric verification and estimate the dose in the patient is feasible. In addition, end-to-end testing on a per-patient basis was possible with the 3D printed phantom. Further refinement of the phantom construction process is needed for routine clinical use.« less

Hillsboro Canal bridge monitoring : [summary].

DOT National Transportation Integrated Search

2011-01-01

Floridas inventory of 148 moveable bridges is : the largest in the nation. Most employ open grid : steel decks, which have important advantages : over solid bridge decks: they can be assembled in : the factory, are lightweight and easy to install;...

Apparatus for Teaching Physics.

ERIC Educational Resources Information Center

Gottlieb, Herbert H., Ed.

1981-01-01

Describes: (1) a variable inductor suitable for an inductance-capacitance bridge consisting of a fixed cylindrical solenoid and a moveable solenoid; (2) long-range apparatus for demonstrating falling bodies; and (3) an apparatus using two lasers to demonstrate ray optics. (SK)

9. DETAIL OF FIXED SUPPORT (A RECENT ADDITION THE ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

9. DETAIL OF FIXED SUPPORT (A RECENT ADDITION -- THE BRIDGE IS NO LONGER MOVEABLE) AND LOWER CHORD OF THROUGH TRUSS, LOOKING SOUTH - Romeo Road, Sanitary & Ship Canal Bridge, Spanning Sanitary & Ship Canal, Romeoville, Will County, IL

Search | Galaxy of Images

Science.gov Websites

; Carriages and Sleighs > Centipedes and Millipedes > Chemical Apparatus > Corals and other Zoophytes > Costume and Dress > Crustaceans > Domestic Life > Electrical Apparatus > Explorers ; Plants - Line Drawings > Plumbing and Bath Equipment > Pop-up and Moveable Books > Postal

SU-E-CAMPUS-T-03: Development and Implementation of An Anthropomorphic Pediatric Spine Phantom for the Assessment of Craniospinal Irradiation Procedures in Proton Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lewis, D; Summers, P; Followill, D

Purpose: To design an anthropomorphic pediatric spine phantom for use in the evaluation of proton therapy facilities for clinical trial participation by the Imaging and Radiation Oncology Core (IROC) Houston QA Center (formerly RPC). Methods: This phantom was designed to perform an end-to-end audit of the proton spine treatment process, including simulation, dose calculation by the treatment planning system (TPS), and proton treatment delivery. The design incorporated materials simulating the thoracic spinal column of a pediatric patient, along with two thermoluminescent dosimeter (TLD)-100 capsules and radiochromic film embedded in the phantom for dose evaluation. Fourteen potential materials were tested tomore » determine relative proton stopping power (RSP) and Hounsfield unit (HU) values. Each material was CT scanned at 120kVp, and the RSP was obtained from depth ionization scans using the Zebra multilayer ion chamber (MLIC) at two energies: 160 MeV and 250 MeV. To determine tissue equivalency, the measured RSP for each material was compared to the RSP calculated by the Eclipse TPS for a given HU. Results: The materials selected as bone, tissue, and cartilage substitutes were Techron HPV Bearing Grade (Boedeker Plastics, Inc.), solid water, and blue water, respectively. The RSP values did not differ by more than 1.8% between the two energies. The measured RSP for each selected material agreed with the RSP calculated by the Eclipse TPS within 1.2%. Conclusion: An anthropomorphic pediatric proton spine phantom was designed to evaluate proton therapy delivery. The inclusion of multiple tissue substitutes increases heterogeneity and the level of difficulty for institutions to successfully treat the phantom. The following attributes will be evaluated: absolute dose agreement, distal range, field width, junction match and right/left dose profile alignment. The phantom will be tested at several institutions using a 5% dose agreement criterion, and a 5%/3mm gamma analysis criterion for the film planes. Work supported by grants CA10953, CA059267, and CA81647 (NCI, DHHS)« less

Low-Stroke Actuation for a Serial Robot

NASA Technical Reports Server (NTRS)

Ihrke, Chris A. (Inventor); Gao, Dalong (Inventor)

2014-01-01

A serial robot includes a base, first and second segments, a proximal joint joining the base to the first segment, and a distal joint. The distal joint that joins the segments is serially arranged and distal with respect to the proximal joint. The robot includes first and second actuators. A first tendon extends from the first actuator to the proximal joint and is selectively moveable via the first actuator. A second tendon extends from the second actuator to the distal joint and is selectively moveable via the second actuator. The robot includes a transmission having at least one gear element which assists rotation of the distal joint when an input force is applied to the proximal and/or distal joints by the first and/or second actuators. A robotic hand having the above robot is also disclosed, as is a robotic system having a torso, arm, and the above-described hand.

Design optimization for accurate flow simulations in 3D printed vascular phantoms derived from computed tomography angiography

NASA Astrophysics Data System (ADS)

Sommer, Kelsey; Izzo, Rick L.; Shepard, Lauren; Podgorsak, Alexander R.; Rudin, Stephen; Siddiqui, Adnan H.; Wilson, Michael F.; Angel, Erin; Said, Zaid; Springer, Michael; Ionita, Ciprian N.

2017-03-01

3D printing has been used to create complex arterial phantoms to advance device testing and physiological condition evaluation. Stereolithographic (STL) files of patient-specific cardiovascular anatomy are acquired to build cardiac vasculature through advanced mesh-manipulation techniques. Management of distal branches in the arterial tree is important to make such phantoms practicable. We investigated methods to manage the distal arterial flow resistance and pressure thus creating physiologically and geometrically accurate phantoms that can be used for simulations of image-guided interventional procedures with new devices. Patient specific CT data were imported into a Vital Imaging workstation, segmented, and exported as STL files. Using a mesh-manipulation program (Meshmixer) we created flow models of the coronary tree. Distal arteries were connected to a compliance chamber. The phantom was then printed using a Stratasys Connex3 multimaterial printer: the vessel in TangoPlus and the fluid flow simulation chamber in Vero. The model was connected to a programmable pump and pressure sensors measured flow characteristics through the phantoms. Physiological flow simulations for patient-specific vasculature were done for six cardiac models (three different vasculatures comparing two new designs). For the coronary phantom we obtained physiologically relevant waves which oscillated between 80 and 120 mmHg and a flow rate of 125 ml/min, within the literature reported values. The pressure wave was similar with those acquired in human patients. Thus we demonstrated that 3D printed phantoms can be used not only to reproduce the correct patient anatomy for device testing in image-guided interventions, but also for physiological simulations. This has great potential to advance treatment assessment and diagnosis.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Myronakis, M; Cai, W; Dhou, S

Purpose: To design a comprehensive open-source, publicly available, graphical user interface (GUI) to facilitate the configuration, generation, processing and use of the 4D Extended Cardiac-Torso (XCAT) phantom. Methods: The XCAT phantom includes over 9000 anatomical objects as well as respiratory, cardiac and tumor motion. It is widely used for research studies in medical imaging and radiotherapy. The phantom generation process involves the configuration of a text script to parameterize the geometry, motion, and composition of the whole body and objects within it, and to generate simulated PET or CT images. To avoid the need for manual editing or script writing,more » our MATLAB-based GUI uses slider controls, drop-down lists, buttons and graphical text input to parameterize and process the phantom. Results: Our GUI can be used to: a) generate parameter files; b) generate the voxelized phantom; c) combine the phantom with a lesion; d) display the phantom; e) produce average and maximum intensity images from the phantom output files; f) incorporate irregular patient breathing patterns; and f) generate DICOM files containing phantom images. The GUI provides local help information using tool-tip strings on the currently selected phantom, minimizing the need for external documentation. The DICOM generation feature is intended to simplify the process of importing the phantom images into radiotherapy treatment planning systems or other clinical software. Conclusion: The GUI simplifies and automates the use of the XCAT phantom for imaging-based research projects in medical imaging or radiotherapy. This has the potential to accelerate research conducted with the XCAT phantom, or to ease the learning curve for new users. This tool does not include the XCAT phantom software itself. We would like to acknowledge funding from MRA, Varian Medical Systems Inc.« less

Deformable adult human phantoms for radiation protection dosimetry: anthropometric data representing size distributions of adult worker populations and software algorithms

NASA Astrophysics Data System (ADS)

Hum Na, Yong; Zhang, Binquan; Zhang, Juying; Caracappa, Peter F.; Xu, X. George

2010-07-01

Computational phantoms representing workers and patients are essential in estimating organ doses from various occupational radiation exposures and medical procedures. Nearly all existing phantoms, however, were purposely designed to match internal and external anatomical features of the Reference Man as defined by the International Commission on Radiological Protection (ICRP). To reduce uncertainty in dose calculations caused by anatomical variations, a new generation of phantoms of varying organ and body sizes is needed. This paper presents detailed anatomical data in tables and graphs that are used to design such size-adjustable phantoms representing a range of adult individuals in terms of the body height, body weight and internal organ volume/mass. Two different sets of information are used to derive the phantom sets: (1) individual internal organ size and volume/mass distribution data derived from the recommendations of the ICRP in Publications 23 and 89 and (2) whole-body height and weight percentile data from the National Health and Nutrition Examination Survey (NHANES 1999-2002). The NHANES height and weight data for 19 year old males and females are used to estimate the distributions of individuals' size, which is unknown, that corresponds to the ICRP organ and tissue distributions. This paper then demonstrates the usage of these anthropometric data in the development of deformable anatomical phantoms. A pair of phantoms—modeled entirely in mesh surfaces—of the adult male and female, RPI-adult male (AM) and RPI-adult female (AF) are used as the base for size-adjustable phantoms. To create percentile-specific phantoms from these two base phantoms, organ surface boundaries are carefully altered according to the tabulated anthropometric data. Software algorithms are developed to automatically match the organ volumes and masses with desired values. Finally, these mesh-based, percentile-specific phantoms are converted into voxel-based phantoms for Monte Carlo radiation transport simulations. This paper also compares absorbed organ doses for the RPI-AM-5th-height and -weight percentile phantom (165 cm in height and 56 kg in weight) and the RPI-AM-95th-height and -weight percentile phantom (188 cm in height and 110 kg in weight) with those for the RPI-AM-50th-height and -weight percentile phantom (176 cm in height and 73 kg in weight) from exposures to 0.5 MeV external photon beams. The results suggest a general finding that the phantoms representing a slimmer and shorter individual male received higher absorbed organ doses because of lesser degree of photon attenuation due to smaller amount of body fat. In particular, doses to the prostate and adrenal in the RPI-AM-5th-height and -weight percentile phantom is about 10% greater than those in the RPI-AM-50th-height and -weight percentile phantom approximating the ICRP Reference Man. On the other hand, the doses to the prostate and adrenal in the RPI-AM-95th-height and -weight percentile phantom are approximately 20% greater than those in the RPI-AM-50th-height and -weight percentile phantom. Although this study only considered the photon radiation of limited energies and irradiation geometries, the potential to improve the organ dose accuracy using the deformable phantom technology is clearly demonstrated.

Deformable adult human phantoms for radiation protection dosimetry: anthropometric data representing size distributions of adult worker populations and software algorithms

PubMed Central

Na, Yong Hum; Zhang, Binquan; Zhang, Juying; Caracappa, Peter F; Xu, X George

2012-01-01

Computational phantoms representing workers and patients are essential in estimating organ doses from various occupational radiation exposures and medical procedures. Nearly all existing phantoms, however, were purposely designed to match internal and external anatomical features of the Reference Man as defined by the International Commission on Radiological Protection (ICRP). To reduce uncertainty in dose calculations caused by anatomical variations, a new generation of phantoms of varying organ and body sizes is needed. This paper presents detailed anatomical data in tables and graphs that are used to design such size-adjustable phantoms representing a range of adult individuals in terms of the body height, body weight and internal organ volume/mass. Two different sets of information are used to derive the phantom sets: (1) individual internal organ size and volume/mass distribution data derived from the recommendations of the ICRP in Publications 23 and 89 and (2) whole-body height and weight percentile data from the National Health and Nutrition Examination Survey (NHANES 1999–2002). The NHANES height and weight data for 19 year old males and females are used to estimate the distributions of individuals’ size, which is unknown, that corresponds to the ICRP organ and tissue distributions. This paper then demonstrates the usage of these anthropometric data in the development of deformable anatomical phantoms. A pair of phantoms—modeled entirely in mesh surfaces—of the adult male and female, RPI-adult male (AM) and RPI-adult female (AF) are used as the base for size-adjustable phantoms. To create percentile-specific phantoms from these two base phantoms, organ surface boundaries are carefully altered according to the tabulated anthropometric data. Software algorithms are developed to automatically match the organ volumes and masses with desired values. Finally, these mesh-based, percentile-specific phantoms are converted into voxel-based phantoms for Monte Carlo radiation transport simulations. This paper also compares absorbed organ doses for the RPI-AM-5th-height and -weight percentile phantom (165 cm in height and 56 kg in weight) and the RPI-AM-95th-height and -weight percentile phantom (188 cm in height and 110 kg in weight)with those for theRPI-AM-50th-height and -weight percentile phantom (176 cm in height and 73 kg in weight) from exposures to 0.5 MeV external photon beams. The results suggest a general finding that the phantoms representing a slimmer and shorter individual male received higher absorbed organ doses because of lesser degree of photon attenuation due to smaller amount of body fat. In particular, doses to the prostate and adrenal in the RPI-AM-5th-height and -weight percentile phantom is about 10% greater than those in the RPI-AM-50th-height and -weight percentile phantom approximating the ICRP Reference Man. On the other hand, the doses to the prostate and adrenal in the RPI-AM-95th-height and -weight percentile phantom are approximately 20% greater than those in the RPI-AM-50th-height and -weight percentile phantom. Although this study only considered the photon radiation of limited energies and irradiation geometries, the potential to improve the organ dose accuracy using the deformable phantom technology is clearly demonstrated. PMID:20551505

SU-F-E-10: Student-Driven Exploration of Radiographic Material Properties, Phantom Construction, and Clinical Workflows Or: The Extraordinary Life of CANDY MAN

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mahon, RN; Riblett, MJ; Hugo, GD

Purpose: To develop a hands-on learning experience that explores the radiological and structural properties of everyday items and applies this knowledge to design a simple phantom for radiotherapy exercises. Methods: Students were asked to compile a list of readily available materials thought to have radiation attenuation properties similar to tissues within the human torso. Participants scanned samples of suggested materials and regions of interest (ROIs) were used to characterize bulk attenuation properties. Properties of each material were assessed via comparison to a Gammex Tissue characterization phantom and used to construct a list of inexpensive near-tissue-equivalent materials. Critical discussions focusing onmore » samples found to differ from student expectations were used to revise and narrow the comprehensive list. From their newly acquired knowledge, students designed and constructed a simple thoracic phantom for use in a simulated clinical workflow. Students were tasked with setting up the phantom and acquiring planning CT images for use in treatment planning and dose delivery. Results: Under engineer and physicist supervision, students were trained to use a CT simulator and acquired images for approximately 60 different foodstuffs, candies, and household items. Through peer discussion, students gained valuable insights and were made to review preconceptions about radiographic material properties. From a subset of imaged materials, a simple phantom was successfully designed and constructed to represent a human thorax. Students received hands-on experience with clinical treatment workflows by learning how to perform CT simulation, create a treatment plan for an embedded tumor, align the phantom for treatment, and deliver a treatment fraction. Conclusion: In this activity, students demonstrated their ability to reason through the radiographic material selection process, construct a simple phantom to specifications, and exercise their knowledge of clinical workflows. Furthermore, the enjoyable and inexpensive nature of this project proved to attract participant interest and drive creative exploration. Mahon and Riblett have nothing to disclose; Hugo has a research agreement with Phillips Medical systems, a license agreement with Varian Medical Systems, research grants from the National Institute of Health. Authors do not have any potential conflicts of interest to disclose.« less

WE-AB-204-03: A Novel 3D Printed Phantom for 4D PET/CT Imaging and SIB Radiotherapy Verification

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soultan, D; Murphy, J; Moiseenko, V

Purpose: To construct and test a 3D printed phantom designed to mimic variable PET tracer uptake seen in lung tumor volumes. To assess segmentation accuracy of sub-volumes of the phantom following 4D PET/CT scanning with ideal and patient-specific respiratory motion. To plan, deliver and verify delivery of PET-driven, gated, simultaneous integrated boost (SIB) radiotherapy plans. Methods: A set of phantoms and inserts were designed and manufactured for a realistic representation of lung cancer gated radiotherapy steps from 4D PET/CT scanning to dose delivery. A cylindrical phantom (40x 120 mm) holds inserts for PET/CT scanning. The novel 3D printed insert dedicatedmore » to 4D PET/CT mimics high PET tracer uptake in the core and lower uptake in the periphery. This insert is a variable density porous cylinder (22.12×70 mm), ABS-P430 thermoplastic, 3D printed by uPrint SE Plus with inner void volume (5.5×42 mm). The square pores (1.8×1.8 mm2 each) fill 50% of outer volume, resulting in a 2:1 SUV ratio of PET-tracer in the void volume with respect to porous volume. A matching in size cylindrical phantom is dedicated to validate gated radiotherapy. It contains eight peripheral holes matching the location of the porous part of the 3D printed insert, and one central hole. These holes accommodate adaptors for Farmer-type ion chamber and cells vials. Results: End-to-end test were performed from 4D PET/CT scanning to transferring data to the planning system and target volume delineation. 4D PET/CT scans were acquired of the phantom with different respiratory motion patterns and gating windows. A measured 2:1 18F-FDG SUV ratio between inner void and outer volume matched the 3D printed design. Conclusion: The novel 3D printed phantom mimics variable PET tracer uptake typical of tumors. Obtained 4D PET/CT scans are suitable for segmentation, treatment planning and delivery in SIB gated treatments of NSCLC.« less

Intravenous volume tomographic pulmonary angiography imaging

NASA Astrophysics Data System (ADS)

Ning, Ruola; Strang, John G.; Chen, Biao; Conover, David L.; Yu, Rongfeng

1999-05-01

This study presents a new intravenous (IV) tomographic angiography imaging technique, called intravenous volume tomographic digital angiography (VTDA) for cross sectional pulmonary angiography. While the advantages of IV-VTDA over spiral CT in terms of volume scanning time and resolution have been validated and reported in our previous papers for head and neck vascular imaging, the superiority of IV-VTDA over spiral CT for cross sectional pulmonary angiography has not been explored yet. The purpose of this study is to demonstrate the advantage of isotropic resolution of IV-VTDA in the x, y and z directions through phantom and animal studies, and to explore its clinical application for detecting clots in pulmonary angiography. A prototype image intensifier-based VTDA imaging system has been designed and constructed by modifying a GE 8800 CT scanner. This system was used for a series of phantom and dog studies. A pulmonary vascular phantom was designed and constructed. The phantom was scanned using the prototype VTDA system for direct 3D reconstruction. Then the same phantom was scanned using a GE CT/i spiral CT scanner using the routine pulmonary CT angiography protocols. IV contrast injection and volume scanning protocols were developed during the dog studies. Both VTDA reconstructed images and spiral CT images of the specially designed phantom were analyzed and compared. The detectability of simulated vessels and clots was assessed as the function of iodine concentration levels, oriented angles, and diameters of the vessels and clots. A set of 3D VTDA reconstruction images of dog pulmonary arteries was obtained with different IV injection rates and isotropic resolution in the x, y and z directions. The results of clot detection studies in dog pulmonary arteries have also been shown. This study presents a new tomographic IV angiography imaging technique for cross sectional pulmonary angiography. The results of phantom and animal studies indicate that IV-VTDA is superior to spiral CT for cross sectional pulmonary angiography.

Design of a digital phantom population for myocardial perfusion SPECT imaging research.

PubMed

Ghaly, Michael; Du, Yong; Fung, George S K; Tsui, Benjamin M W; Links, Jonathan M; Frey, Eric

2014-06-21

Digital phantoms and Monte Carlo (MC) simulations have become important tools for optimizing and evaluating instrumentation, acquisition and processing methods for myocardial perfusion SPECT (MPS). In this work, we designed a new adult digital phantom population and generated corresponding Tc-99m and Tl-201 projections for use in MPS research. The population is based on the three-dimensional XCAT phantom with organ parameters sampled from the Emory PET Torso Model Database. Phantoms included three variations each in body size, heart size, and subcutaneous adipose tissue level, for a total of 27 phantoms of each gender. The SimSET MC code and angular response functions were used to model interactions in the body and the collimator-detector system, respectively. We divided each phantom into seven organs, each simulated separately, allowing use of post-simulation summing to efficiently model uptake variations. Also, we adapted and used a criterion based on the relative Poisson effective count level to determine the required number of simulated photons for each simulated organ. This technique provided a quantitative estimate of the true noise in the simulated projection data, including residual MC simulation noise. Projections were generated in 1 keV wide energy windows from 48-184 keV assuming perfect energy resolution to permit study of the effects of window width, energy resolution, and crosstalk in the context of dual isotope MPS. We have developed a comprehensive method for efficiently simulating realistic projections for a realistic population of phantoms in the context of MPS imaging. The new phantom population and realistic database of simulated projections will be useful in performing mathematical and human observer studies to evaluate various acquisition and processing methods such as optimizing the energy window width, investigating the effect of energy resolution on image quality and evaluating compensation methods for degrading factors such as crosstalk in the context of single and dual isotope MPS.

Design of a digital phantom population for myocardial perfusion SPECT imaging research

NASA Astrophysics Data System (ADS)

Ghaly, Michael; Du, Yong; Fung, George S. K.; Tsui, Benjamin M. W.; Links, Jonathan M.; Frey, Eric

2014-06-01

Digital phantoms and Monte Carlo (MC) simulations have become important tools for optimizing and evaluating instrumentation, acquisition and processing methods for myocardial perfusion SPECT (MPS). In this work, we designed a new adult digital phantom population and generated corresponding Tc-99m and Tl-201 projections for use in MPS research. The population is based on the three-dimensional XCAT phantom with organ parameters sampled from the Emory PET Torso Model Database. Phantoms included three variations each in body size, heart size, and subcutaneous adipose tissue level, for a total of 27 phantoms of each gender. The SimSET MC code and angular response functions were used to model interactions in the body and the collimator-detector system, respectively. We divided each phantom into seven organs, each simulated separately, allowing use of post-simulation summing to efficiently model uptake variations. Also, we adapted and used a criterion based on the relative Poisson effective count level to determine the required number of simulated photons for each simulated organ. This technique provided a quantitative estimate of the true noise in the simulated projection data, including residual MC simulation noise. Projections were generated in 1 keV wide energy windows from 48-184 keV assuming perfect energy resolution to permit study of the effects of window width, energy resolution, and crosstalk in the context of dual isotope MPS. We have developed a comprehensive method for efficiently simulating realistic projections for a realistic population of phantoms in the context of MPS imaging. The new phantom population and realistic database of simulated projections will be useful in performing mathematical and human observer studies to evaluate various acquisition and processing methods such as optimizing the energy window width, investigating the effect of energy resolution on image quality and evaluating compensation methods for degrading factors such as crosstalk in the context of single and dual isotope MPS.

Two-dimensional multi-frequency imaging of a tumor inclusion in a homogeneous breast phantom using the harmonic motion Doppler imaging method.

PubMed

Tafreshi, Azadeh Kamali; Top, Can Barış; Gençer, Nevzat Güneri

2017-06-21

Harmonic motion microwave Doppler imaging (HMMDI) is a novel imaging modality for imaging the coupled electrical and mechanical properties of body tissues. In this paper, we used two experimental systems with different receiver configurations to obtain HMMDI images from tissue-mimicking phantoms at multiple vibration frequencies between 15 Hz and 35 Hz. In the first system, we used a spectrum analyzer to obtain the Doppler data in the frequency domain, while in the second one, we used a homodyne receiver that was designed to acquire time-domain data. The developed phantoms mimicked the elastic and dielectric properties of breast fat tissue, and included a [Formula: see text] mm cylindrical inclusion representing the tumor. A focused ultrasound probe was mechanically scanned in two lateral dimensions to obtain two-dimensional HMMDI images of the phantoms. The inclusions were resolved inside the fat phantom using both experimental setups. The image resolution increased with increasing vibration frequency. The designed receiver showed higher sensitivity than the spectrum analyzer measurements. The results also showed that time-domain data acquisition should be used to fully exploit the potential of the HMMDI method.

Two-dimensional multi-frequency imaging of a tumor inclusion in a homogeneous breast phantom using the harmonic motion Doppler imaging method

NASA Astrophysics Data System (ADS)

Kamali Tafreshi, Azadeh; Barış Top, Can; Güneri Gençer, Nevzat

2017-06-01

Harmonic motion microwave Doppler imaging (HMMDI) is a novel imaging modality for imaging the coupled electrical and mechanical properties of body tissues. In this paper, we used two experimental systems with different receiver configurations to obtain HMMDI images from tissue-mimicking phantoms at multiple vibration frequencies between 15 Hz and 35 Hz. In the first system, we used a spectrum analyzer to obtain the Doppler data in the frequency domain, while in the second one, we used a homodyne receiver that was designed to acquire time-domain data. The developed phantoms mimicked the elastic and dielectric properties of breast fat tissue, and included a 14~\\text{mm}× 9 mm cylindrical inclusion representing the tumor. A focused ultrasound probe was mechanically scanned in two lateral dimensions to obtain two-dimensional HMMDI images of the phantoms. The inclusions were resolved inside the fat phantom using both experimental setups. The image resolution increased with increasing vibration frequency. The designed receiver showed higher sensitivity than the spectrum analyzer measurements. The results also showed that time-domain data acquisition should be used to fully exploit the potential of the HMMDI method.

GMT/local-time conversion chart

NASA Technical Reports Server (NTRS)

Creveling, C. J.

1968-01-01

GMT/local-time conversion is made by a longitude pocket instrument that automatically indicates desired information by simply manipulating the moveable portion of the instrument in accordance with a set of simple instructions imprinted on the reverse side of the instrument.

Technical Note: Rod phantom analysis for comparison of PET detector sampling and reconstruction methods.

PubMed

Wollenweber, Scott D; Kemp, Brad J

2016-11-01

This investigation aimed to develop a scanner quantification performance methodology and compare multiple metrics between two scanners under different imaging conditions. Most PET scanners are designed to work over a wide dynamic range of patient imaging conditions. Clinical constraints, however, often impact the realization of the entitlement performance for a particular scanner design. Using less injected dose and imaging for a shorter time are often key considerations, all while maintaining "acceptable" image quality and quantitative capability. A dual phantom measurement including resolution inserts was used to measure the effects of in-plane (x, y) and axial (z) system resolution between two PET/CT systems with different block detector crystal dimensions. One of the scanners had significantly thinner slices. Several quantitative measures, including feature contrast recovery, max/min value, and feature profile accuracy were derived from the resulting data and compared between the two scanners and multiple phantoms and alignments. At the clinically relevant count levels used, the scanner with thinner slices had improved performance of approximately 2%, averaged over phantom alignments, measures, and reconstruction methods, for the head-sized phantom, mainly demonstrated with the rods aligned perpendicular to the scanner axis. That same scanner had a slightly decreased performance of -1% for the larger body-size phantom, mostly due to an apparent noise increase in the images. Most of the differences in the metrics between the two scanners were less than 10%. Using the proposed scanner performance methodology, it was shown that smaller detector elements and a larger number of image voxels require higher count density in order to demonstrate improved image quality and quantitation. In a body imaging scenario under typical clinical conditions, the potential advantages of the design must overcome increases in noise due to lower count density.

SU-E-I-24: Method for CT Automatic Exposure Control Verification

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gracia, M; Olasolo, J; Martin, M

Purpose: Design of a phantom and a simple method for the automatic exposure control (AEC) verification in CT. This verification is included in the computed tomography (CT) Spanish Quality Assurance Protocol. Methods: The phantom design is made from the head and the body phantom used for the CTDI measurement and PMMA plates (35×35 cm2) of 10 cm thickness. Thereby, three different thicknesses along the longitudinal axis are obtained which permit to evaluate the longitudinal AEC performance. Otherwise, the existent asymmetry in the PMMA layers helps to assess angular and 3D AEC operation.Recent acquisition in our hospital (August 2014) of Nomexmore » electrometer (PTW), together with the 10 cm pencil ionization chamber, led to register dose rate as a function of time. Measurements with this chamber fixed at 0° and 90° on the gantry where made on five multidetector-CTs from principal manufacturers. Results: Individual analysis of measurements shows dose rate variation as a function of phantom thickness. The comparative analysis shows that dose rate is kept constant in the head and neck phantom while the PMMA phantom exhibits an abrupt variation between both results, being greater results at 90° as the thickness of the phantom is 3.5 times larger than in the perpendicular direction. Conclusion: Proposed method is simple, quick and reproducible. Results obtained let a qualitative evaluation of the AEC and they are consistent with the expected behavior. A line of future development is to quantitatively study the intensity modulation and parameters of image quality, and a possible comparative study between different manufacturers.« less

Characterization of 3D printing techniques: Toward patient specific quality assurance spine-shaped phantom for stereotactic body radiation therapy.

PubMed

Kim, Min-Joo; Lee, Seu-Ran; Lee, Min-Young; Sohn, Jason W; Yun, Hyong Geon; Choi, Joon Yong; Jeon, Sang Won; Suh, Tae Suk

2017-01-01

Development and comparison of spine-shaped phantoms generated by two different 3D-printing technologies, digital light processing (DLP) and Polyjet has been purposed to utilize in patient-specific quality assurance (QA) of stereotactic body radiation treatment. The developed 3D-printed spine QA phantom consisted of an acrylic body phantom and a 3D-printed spine shaped object. DLP and Polyjet 3D printers using a high-density acrylic polymer were employed to produce spine-shaped phantoms based on CT images. Image fusion was performed to evaluate the reproducibility of our phantom, and the Hounsfield units (HUs) were measured based on each CT image. Two different intensity-modulated radiotherapy plans based on both CT phantom image sets from the two printed spine-shaped phantoms with acrylic body phantoms were designed to deliver 16 Gy dose to the planning target volume (PTV) and were compared for target coverage and normal organ-sparing. Image fusion demonstrated good reproducibility of the developed phantom. The HU values of the DLP- and Polyjet-printed spine vertebrae differed by 54.3 on average. The PTV Dmax dose for the DLP-generated phantom was about 1.488 Gy higher than that for the Polyjet-generated phantom. The organs at risk received a lower dose for the 3D printed spine-shaped phantom image using the DLP technique than for the phantom image using the Polyjet technique. Despite using the same material for printing the spine-shaped phantom, these phantoms generated by different 3D printing techniques, DLP and Polyjet, showed different HU values and these differently appearing HU values according to the printing technique could be an extra consideration for developing the 3D printed spine-shaped phantom depending on the patient's age and the density of the spinal bone. Therefore, the 3D printing technique and materials should be carefully chosen by taking into account the condition of the patient in order to accurately produce 3D printed patient-specific QA phantom.

Characterization of 3D printing techniques: Toward patient specific quality assurance spine-shaped phantom for stereotactic body radiation therapy

PubMed Central

Lee, Min-Young; Sohn, Jason W.; Yun, Hyong Geon; Choi, Joon Yong; Jeon, Sang Won

2017-01-01

Development and comparison of spine-shaped phantoms generated by two different 3D-printing technologies, digital light processing (DLP) and Polyjet has been purposed to utilize in patient-specific quality assurance (QA) of stereotactic body radiation treatment. The developed 3D-printed spine QA phantom consisted of an acrylic body phantom and a 3D-printed spine shaped object. DLP and Polyjet 3D printers using a high-density acrylic polymer were employed to produce spine-shaped phantoms based on CT images. Image fusion was performed to evaluate the reproducibility of our phantom, and the Hounsfield units (HUs) were measured based on each CT image. Two different intensity-modulated radiotherapy plans based on both CT phantom image sets from the two printed spine-shaped phantoms with acrylic body phantoms were designed to deliver 16 Gy dose to the planning target volume (PTV) and were compared for target coverage and normal organ-sparing. Image fusion demonstrated good reproducibility of the developed phantom. The HU values of the DLP- and Polyjet-printed spine vertebrae differed by 54.3 on average. The PTV Dmax dose for the DLP-generated phantom was about 1.488 Gy higher than that for the Polyjet-generated phantom. The organs at risk received a lower dose for the 3D printed spine-shaped phantom image using the DLP technique than for the phantom image using the Polyjet technique. Despite using the same material for printing the spine-shaped phantom, these phantoms generated by different 3D printing techniques, DLP and Polyjet, showed different HU values and these differently appearing HU values according to the printing technique could be an extra consideration for developing the 3D printed spine-shaped phantom depending on the patient’s age and the density of the spinal bone. Therefore, the 3D printing technique and materials should be carefully chosen by taking into account the condition of the patient in order to accurately produce 3D printed patient-specific QA phantom. PMID:28472175

TU-H-CAMPUS-IeP2-05: Breast and Soft Tissue-Equivalent 3D Printed Phantoms for Imaging and Dosimetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hintenlang, D; Terracino, B

Purpose: The study has the goal to demonstrate that breast and soft tissue-equivalent phantoms for dosimetry applications in the diagnostic energy range can be fabricated using common 3D printing methods. Methods: 3D printing provides the opportunity to rapidly prototype uniquely designed objects from a variety of materials. Common 3D printers are usually limited to printing objects based on thermoplastic materials such as PLA, or ABS. The most commonly available plastic is PLA, which has a density significantly greater than soft tissue. We utilized a popular 3D printer to demonstrate that tissue specific phantom materials can be generated through the carefulmore » selection of 3D printing parameters. A series of stepwedges were designed and printed using a Makerbot Replicator2 3D printing system. The print file provides custom adjustment of the infill density, orientation and position of the object on the printer stage, selection of infill patterns, and other control parameters. The x-ray attenuation and uniformity of fabricated phantoms were evaluated and compared to common tissue-equivalent phantom materials, acrylic and BR12. X-ray exposure measurements were made using narrow beam geometry on a clinical mammography unit at 28 kVp on the series of phantoms. The 3D printed phantoms were imaged at 28 kVp to visualize the internal structure and uniformity in different planes of the phantoms. Results: By utilizing specific in-fill density and patterns we are able to produce a phantom closely matching the attenuation characteristics of BR12 at 28 kVp. The in-fill patterns used are heterogeneous, so a judicious selection of fill pattern and the orientation of the fill pattern must be made in order to obtain homogenous attenuation along the intended direction of beam propagation. Conclusions: By careful manipulation of the printing parameters, breast and soft tissue-equivalent phantoms appropriate for use at imaging energies can be fabricated using 3D printing techniques.« less

Improving the realism of white matter numerical phantoms: a step towards a better understanding of the influence of structural disorders in diffusion MRI

NASA Astrophysics Data System (ADS)

Ginsburger, Kévin; Poupon, Fabrice; Beaujoin, Justine; Estournet, Delphine; Matuschke, Felix; Mangin, Jean-François; Axer, Markus; Poupon, Cyril

2018-02-01

White matter is composed of irregularly packed axons leading to a structural disorder in the extra-axonal space. Diffusion MRI experiments using oscillating gradient spin echo sequences have shown that the diffusivity transverse to axons in this extra-axonal space is dependent on the frequency of the employed sequence. In this study, we observe the same frequency-dependence using 3D simulations of the diffusion process in disordered media. We design a novel white matter numerical phantom generation algorithm which constructs biomimicking geometric configurations with few design parameters, and enables to control the level of disorder of the generated phantoms. The influence of various geometrical parameters present in white matter, such as global angular dispersion, tortuosity, presence of Ranvier nodes, beading, on the extra-cellular perpendicular diffusivity frequency dependence was investigated by simulating the diffusion process in numerical phantoms of increasing complexity and fitting the resulting simulated diffusion MR signal attenuation with an adequate analytical model designed for trapezoidal OGSE sequences. This work suggests that angular dispersion and especially beading have non-negligible effects on this extracellular diffusion metrics that may be measured using standard OGSE DW-MRI clinical protocols.

Dual-resolution dose assessments for proton beamlet using MCNPX 2.6.0

NASA Astrophysics Data System (ADS)

Chao, T. C.; Wei, S. C.; Wu, S. W.; Tung, C. J.; Tu, S. J.; Cheng, H. W.; Lee, C. C.

2015-11-01

The purpose of this study is to access proton dose distribution in dual resolution phantoms using MCNPX 2.6.0. The dual resolution phantom uses higher resolution in Bragg peak, area near large dose gradient, or heterogeneous interface and lower resolution in the rest. MCNPX 2.6.0 was installed in Ubuntu 10.04 with MPI for parallel computing. FMesh1 tallies were utilized to record the energy deposition which is a special designed tally for voxel phantoms that converts dose deposition from fluence. 60 and 120 MeV narrow proton beam were incident into Coarse, Dual and Fine resolution phantoms with pure water, water-bone-water and water-air-water setups. The doses in coarse resolution phantoms are underestimated owing to partial volume effect. The dose distributions in dual or high resolution phantoms agreed well with each other and dual resolution phantoms were at least 10 times more efficient than fine resolution one. Because the secondary particle range is much longer in air than in water, the dose of low density region may be under-estimated if the resolution or calculation grid is not small enough.

A comprehensive dose assessment of irradiated hand by iridium-192 source in industrial radiography.

PubMed

Hosseini Pooya, S M; Dashtipour, M R; Paydar, R; Mianji, F; Pourshahab, B

2017-09-01

Among the various incidents in industrial radiography, inadvertent handling of sources by hands is one of the most frequent incidents in which some parts of the hands may be locally exposed to high doses. An accurate assessment of extremity dose assists medical doctors in selecting appropriate treatments, preventing the injury expansion in the region. In this study, a phantom was designed to simulate a fisted hand of a radiographer when the worker holds a radioactive source in their hands. The local doses were measured using implanted TLDs in the phantom at different distances from a source. Furthermore, skin dose distribution was measured by Gaf-chromic films in the palm region of the phantom. The reliability of the measurements has been studied via analytical as well as Monte-Carlo simulation methods. The results showed that the new phantom design can be used reliably in extremity dose assessments, particularly at the points next to the source.

Precision zero-home locator

DOEpatents

Stone, William J.

1986-01-01

A zero-home locator includes a fixed phototransistor switch and a moveable actuator including two symmetrical, opposed wedges, each wedge defining a point at which switching occurs. The zero-home location is the average of the positions of the points defined by the wedges.

Precision zero-home locator

DOEpatents

Stone, W.J.

1983-10-31

A zero-home locator includes a fixed phototransistor switch and a moveable actuator including two symmetrical, opposed wedges, each wedge defining a point at which switching occurs. The zero-home location is the average of the positions of the points defined by the wedges.

Variable reluctance switch avoids contact corrosion and contact bounce

NASA Technical Reports Server (NTRS)

Watson, P. C.

1967-01-01

Variable reluctance switch avoids contact corrosion and bounce in a hostile environment. It consists of a wire-wound magnetic core and moveable bridge piece that alters the core flux pattern to produce an electrical output useful for switching control media.

Design of a dynamic optical tissue phantom to model extravasation pharmacokinetics

NASA Astrophysics Data System (ADS)

Zhang, Jane Y.; Ergin, Aysegul; Andken, Kerry Lee; Sheng, Chao; Bigio, Irving J.

2010-02-01

We describe an optical tissue phantom that enables the simulation of drug extravasation from microvessels and validates computational compartmental models of drug delivery. The phantom consists of a microdialysis tubing bundle to simulate the permeable blood vessels, immersed in either an aqueous suspension of titanium dioxide (TiO2) or a TiO2 mixed agarose scattering medium. Drug administration is represented by a dye circulated through this porous microdialysis tubing bundle. Optical pharmacokinetic (OP) methods are used to measure changes in the absorption coefficient of the scattering medium due to the arrival and diffusion of the dye. We have established particle sizedependent concentration profiles over time of phantom drug delivery by intravenous (IV) and intra-arterial (IA) routes. Additionally, pharmacokinetic compartmental models are implemented in computer simulations for the conditions studied within the phantom. The simulated concentration-time profiles agree well with measurements from the phantom. The results are encouraging for future optical pharmacokinetic method development, both physical and computational, to understand drug extravasation under various physiological conditions.

KSC-08pd0606

NASA Image and Video Library

2008-02-11

KENNEDY SPACE CENTER, FLA. -- In the Space Station Processing Facility at NASA's Kennedy Space Center, an overhead crane moves the Special Purpose Dexterous Manipulator, known as Dextre, to the payload canister for transfer to Launch Pad 39A. Dextre is a sophisticated dual-armed robot, which is part of Canada's contribution to the International Space Station. Along with Canadarm2, which is called the Space Station Remote Manipulator System, and a moveable work platform called the Mobile Base System, these three elements form a robotic system called the Mobile Servicing System. The three components have been designed to work together or independently. Dextre is part of the payload on space shuttle Endeavour's STS-123 mission, targeted for launch March 11. Photo courtesy of The Boeing Company

KSC-08pd0608

NASA Image and Video Library

2008-02-11

KENNEDY SPACE CENTER, FLA. -- In the Space Station Processing Facility at NASA's Kennedy Space Center, the Special Purpose Dexterous Manipulator, known as Dextre, moves nearer to the payload canister where it will be installed for transfer to Launch Pad 39A. Dextre is a sophisticated dual-armed robot, which is part of Canada's contribution to the International Space Station. Along with Canadarm2, which is called the Space Station Remote Manipulator System, and a moveable work platform called the Mobile Base System, these three elements form a robotic system called the Mobile Servicing System. The three components have been designed to work together or independently. Dextre is part of the payload on space shuttle Endeavour's STS-123 mission, targeted for launch March 11. Photo courtesy of The Boeing Company

KSC-08pd0604

NASA Image and Video Library

2008-02-11

KENNEDY SPACE CENTER, FLA. -- In the Space Station Processing Facility at NASA's Kennedy Space Center, the Special Purpose Dexterous Manipulator, known as Dextre, moves across the facility via an overhead crane to the payload canister for transfer to Launch Pad 39A. Dextre is a sophisticated dual-armed robot, which is part of Canada's contribution to the International Space Station. Along with Canadarm2, which is called the Space Station Remote Manipulator System, and a moveable work platform called the Mobile Base System, these three elements form a robotic system called the Mobile Servicing System. The three components have been designed to work together or independently. Dextre is part of the payload on space shuttle Endeavour's STS-123 mission, targeted for launch March 11. Photo courtesy of The Boeing Company

KSC-08pd0607

NASA Image and Video Library

2008-02-11

KENNEDY SPACE CENTER, FLA. -- In the Space Station Processing Facility at NASA's Kennedy Space Center, the Special Purpose Dexterous Manipulator, known as Dextre, moves closer to the payload canister where it will be installed for transfer to Launch Pad 39A. Dextre is a sophisticated dual-armed robot, which is part of Canada's contribution to the International Space Station. Along with Canadarm2, which is called the Space Station Remote Manipulator System, and a moveable work platform called the Mobile Base System, these three elements form a robotic system called the Mobile Servicing System. The three components have been designed to work together or independently. Dextre is part of the payload on space shuttle Endeavour's STS-123 mission, targeted for launch March 11. Photo courtesy of The Boeing Company

KSC-07pd2871

NASA Image and Video Library

2007-10-01

KENNEDY SPACE CENTER, FLA. -- In the Space Station Processing Facility at NASA's Kennedy Space Center, technicians help guide the starboard arm of the Special Purpose Dexterous Manipulator, known as Dextre, into place for installation on the base. Dextre is a sophisticated dual-armed robot, which is part of Canada's contribution to the International Space Station (ISS). Along with Canadarm2, whose technical name is the Space Station Remote Manipulator System, and a moveable work platform called the Mobile Base System, these three elements form a robotic system called the Mobile Servicing System, or MSS. The three components have been designed to work together or independently. Dextre is part of the payload scheduled on mission STS-123, targeted to launch Feb. 14. Photo credit: NASA/George Shelton

KSC-07pd2863

NASA Image and Video Library

2007-10-01

KENNEDY SPACE CENTER, FLA. -- In the Space Station Processing Facility at NASA's Kennedy Space Center, the starboard arm of the Special Purpose Dexterous Manipulator, known as Dextre, is ready to be installed on the base. Dextre is a sophisticated dual-armed robot, which is part of Canada's contribution to the International Space Station ISS. Along with Canadarm2, whose technical name is the Space Station Remote Manipulator System, and a moveable work platform called the Mobile Base System, these three elements form a robotic system called the Mobile Servicing System, or MSS. The three components have been designed to work together or independently. Dextre is part of the payload scheduled on mission STS-123, targeted to launch Feb. 14. Photo credit: NASA/George Shelton

KSC-07pd2870

NASA Image and Video Library

2007-10-01

KENNEDY SPACE CENTER, FLA. -- In the Space Station Processing Facility at NASA's Kennedy Space Center, technicians help guide the starboard arm of the Special Purpose Dexterous Manipulator, known as Dextre, into place for installation on the base. Dextre is a sophisticated dual-armed robot, which is part of Canada's contribution to the International Space Station (ISS). Along with Canadarm2, whose technical name is the Space Station Remote Manipulator System, and a moveable work platform called the Mobile Base System, these three elements form a robotic system called the Mobile Servicing System, or MSS. The three components have been designed to work together or independently. Dextre is part of the payload scheduled on mission STS-123, targeted to launch Feb. 14. Photo credit: NASA/George Shelton

KSC-07pd2866

NASA Image and Video Library

2007-10-01

KENNEDY SPACE CENTER, FLA. -- In the Space Station Processing Facility at NASA's Kennedy Space Center, the starboard arm of the Special Purpose Dexterous Manipulator, known as Dextre, is moved across the facility. The arm will be installed on the base. Dextre is a sophisticated dual-armed robot, which is part of Canada's contribution to the International Space Station (ISS). Along with Canadarm2, whose technical name is the Space Station Remote Manipulator System, and a moveable work platform called the Mobile Base System, these three elements form a robotic system called the Mobile Servicing System, or MSS. The three components have been designed to work together or independently. Dextre is part of the payload scheduled on mission STS-123, targeted to launch Feb. 14. Photo credit: NASA/George Shelton

Development of Raman-Mie lidar system for aerosol and water vapor profiling

NASA Astrophysics Data System (ADS)

Deng, Qian; Wang, Zhenzhu; Xu, Jiwei; Tan, Min; Wu, Decheng; Xie, Chenbo; Liu, Dong; Wang, Yingjian

2018-03-01

Aerosol and water vapor are two important atmospheric parameters. The accurate quantification of diurnal variation of these parameters are very useful for environment assessment and climate change studies. A moveable, compact and unattended lidar system based on modular design is developed for aerosol extinction coefficients and water vapor mixing ratios measurements. In the southern suburbs of Beijing, the continuous observation was carried out by this lidar since the middle of the year of 2017. The lidar equipment is presented and the case study is also described in this paper. The observational results show that the lidar kept a very good status from the long-time continuous measurements which is suitable for networking especially in meteorological research field.

Measurement of in-phantom neutron flux and gamma dose in Tehran research reactor boron neutron capture therapy beam line.

PubMed

Bavarnegin, Elham; Sadremomtaz, Alireza; Khalafi, Hossein; Kasesaz, Yaser

2016-01-01

Determination of in-phantom quality factors of Tehran research reactor (TRR) boron neutron capture therapy (BNCT) beam. The doses from thermal neutron reactions with 14N and 10B are calculated by kinetic energy released per unit mass approach, after measuring thermal neutron flux using neutron activation technique. Gamma dose is measured using TLD-700 dosimeter. Different dose components have been measured in a head phantom which has been designed and constructed for BNCT purpose in TRR. Different in-phantom beam quality factors have also been determined. This study demonstrates that the TRR BNCT beam line has potential for treatment of superficial tumors.

Development of digital rectangular phantoms for quality controls of medical primary monitors in RIS-PACS systems

NASA Astrophysics Data System (ADS)

Mattacchioni, A.; Cristianini, M.; Lo Bosco, A.

2013-03-01

The purpose of this paper is to project digital rectangular phantoms, Di.Recta Multipurpose Phantoms (Di.Recta MP) for quality controls of primary high resolution medical monitors. The first approach for the monitors quality evaluation is represented by AAPM tests using multipurpose TG-18- CQ phantoms. The TG18-QC patterns are available in two sizes: 1024x1024 and 2048x2048 and the use of these phantoms requires a correct monitor setup. The study demonstrates that this type of phantoms is suitable for CRT monitors with adequate settings procedures. In the second step LCD monitors are analysed. Different types of primary monitors are included in a range between 2 and 5 Mp. The difference between the resolution of monitors and phantoms does not allow a complete analysis of the entire system, just moving phantoms in different positions. Of course, the analysis of images in the peripheral regions of medical monitors can not be neglected, especially because of the possible legal implications. A simpler analysis of these areas can be done through the use of rectangular phantoms in place of square ones. Furthermore, because of different technology, also different analysis patches are necessary for these types of monitors. Therefore, there are proposed digital rectangular phantoms, Di.Recta MP, compatible with the spatial resolution of most of commercial monitors. These phantoms are designed to simulate typical radiological conditions to determine the presence of significant defects using appropriate patches such as luminance, contrast, noise patterns. Finally a preliminary study of dedicate Di.Recta MP are proposed for LED monitors.

Model Development and Model-Based Control Design for High Performance Nonlinear Smart Systems

DTIC Science & Technology

2007-11-20

potentially impact a broad range of flow control problems of interest to the Air Force and Boeing. Point of contact: James Mabe , Boeing Phantom Works...rotorcraft blades. In both cases, models and control designs will be validated using data from Boeing experiments and flight tests. Point of contact: James ... Mabe , Boeing Phantom Works, Seattle, WA, 206-655-0091. 3. PZT Unimorphs – Boeing: Nonlinear structural models developed through AFOSR support are being

Design and Evaluation of a Cochlear Implant Strategy Based on a “Phantom” Channel

PubMed Central

Nogueira, Waldo; Litvak, Leonid M.; Saoji, Aniket A.; Büchner, Andreas

2015-01-01

Unbalanced bipolar stimulation, delivered using charge balanced pulses, was used to produce “Phantom stimulation”, stimulation beyond the most apical contact of a cochlear implant’s electrode array. The Phantom channel was allocated audio frequencies below 300Hz in a speech coding strategy, conveying energy some two octaves lower than the clinical strategy and hence delivering the fundamental frequency of speech and of many musical tones. A group of 12 Advanced Bionics cochlear implant recipients took part in a chronic study investigating the fitting of the Phantom strategy and speech and music perception when using Phantom. The evaluation of speech in noise was performed immediately after fitting Phantom for the first time (Session 1) and after one month of take-home experience (Session 2). A repeated measures of analysis of variance (ANOVA) within factors strategy (Clinical, Phantom) and interaction time (Session 1, Session 2) revealed a significant effect for the interaction time and strategy. Phantom obtained a significant improvement in speech intelligibility after one month of use. Furthermore, a trend towards a better performance with Phantom (48%) with respect to F120 (37%) after 1 month of use failed to reach significance after type 1 error correction. Questionnaire results show a preference for Phantom when listening to music, likely driven by an improved balance between high and low frequencies. PMID:25806818

Daily quality assurance phantom for ultrasound image guided radiation therapy

PubMed Central

Drever, Laura

2007-01-01

A simple phantom was designed, constructed, tested, and clinically implemented for daily quality assurance (QA) of an ultrasound‐image‐guided radiation therapy (US‐IGRT) system, the Restitu Ultrasound system (Resonant Medical, Montreal, QC). The phantom consists of a high signal echogenic background gel surrounding a low signal hypoechoic egg‐shaped target. Daily QA checks involve ultrasound imaging of the phantom and segmenting of the embedded target using the automated tools available on the US‐IGRT system. This process serves to confirm system hardware and software functions and, in particular, accurate determination of the target position. Experiments were conducted to test the stability of the phantom at room temperature, its tissue‐mimicking properties, the reproducibility of target position measurements, and the usefulness of the phantom as a daily QA device. The phantom proved stable at room temperature, exhibited no evidence of bacterial or fungal invasion in 9 months, and showed limited desiccation (resulting in a monthly reduction in ultrasound‐measured volume of approximately 0.2 cm3). Furthermore, the phantom was shown to be nearly tissue‐mimicking, with speed of sound in the phantom estimated to be 0.8% higher than that assumed by the scanner calibration. The phantom performs well in a clinical setting, owing to its light weight and ease of operation. It provides reproducible measures of target position even with multiple users. At our center, the phantom is being used for daily QA of the US‐IGRT system with clinically acceptable tolerances of ±1 cm3 on target volume and ±2 mm on target position. For routine daily QA, this phantom is a good alternative to the manufacturer‐supplied calibration phantom, and we recommended that that larger phantom be reserved for less frequent, more detailed QA checks and system calibration. PACS numbers: 87.66.Xa, 87.63.Df

Matroshka-R Phantom experiment

NASA Image and Video Library

2006-12-01

ISS014-E-09091 (December 2006) --- The European Matroshka-R Phantom experiment was photographed by an Expedition 14 crewmember in the Zvezda Service Module of the International Space Station. Matroshka, the name for the traditional Russian set of nestling dolls, is an antroph-amorphous model of a human torso designed for radiation studies.

Viscosity measuring using microcantilevers

DOEpatents

Oden, Patrick Ian

2001-01-01

A method for the measurement of the viscosity of a fluid uses a micromachined cantilever mounted on a moveable base. As the base is rastered while in contact with the fluid, the deflection of the cantilever is measured and the viscosity determined by comparison with standards.

Thyroid Scan and Uptake

MedlinePlus

... minutes prior to the test. When it is time for the imaging to begin, you will lie down on a moveable examination table with your head tipped backward and neck extended. The gamma camera will then take a series of images, capturing images of the thyroid gland ...

Dose verification to cochlea during gamma knife radiosurgery of acoustic schwannoma using MOSFET dosimeter.

PubMed

Sharma, Sunil D; Kumar, Rajesh; Akhilesh, Philomina; Pendse, Anil M; Deshpande, Sudesh; Misra, Basant K

2012-01-01

Dose verification to cochlea using metal oxide semiconductor field effect transistor (MOSFET) dosimeter using a specially designed multi slice head and neck phantom during the treatment of acoustic schwannoma by Gamma Knife radiosurgery unit. A multi slice polystyrene head phantom was designed and fabricated for measurement of dose to cochlea during the treatment of the acoustic schwannoma. The phantom has provision to position the MOSFET dosimeters at the desired location precisely. MOSFET dosimeters of 0.2 mm x 0.2 mm x 0.5 μm were used to measure the dose to the cochlea. CT scans of the phantom with MOSFETs in situ were taken along with Leksell frame. The treatment plans of five patients treated earlier for acoustic schwannoma were transferred to the phantom. Dose and coordinates of maximum dose point inside the cochlea were derived. The phantom along with the MOSFET dosimeters was irradiated to deliver the planned treatment and dose received by cochlea were measured. The treatment planning system (TPS) estimated and measured dose to the cochlea were in the range of 7.4 - 8.4 Gy and 7.1 - 8 Gy, respectively. The maximum variation between TPS calculated and measured dose to cochlea was 5%. The measured dose values were found in good agreement with the dose values calculated using the TPS. The MOSFET dosimeter can be a suitable choice for routine dose verification in the Gamma Knife radiosurgery.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kiarashi, Nooshin; Nolte, Adam C.; Sturgeon, Gregory M.

Purpose: Physical phantoms are essential for the development, optimization, and evaluation of x-ray breast imaging systems. Recognizing the major effect of anatomy on image quality and clinical performance, such phantoms should ideally reflect the three-dimensional structure of the human breast. Currently, there is no commercially available three-dimensional physical breast phantom that is anthropomorphic. The authors present the development of a new suite of physical breast phantoms based on human data. Methods: The phantoms were designed to match the extended cardiac-torso virtual breast phantoms that were based on dedicated breast computed tomography images of human subjects. The phantoms were fabricated bymore » high-resolution multimaterial additive manufacturing (3D printing) technology. The glandular equivalency of the photopolymer materials was measured relative to breast tissue-equivalent plastic materials. Based on the current state-of-the-art in the technology and available materials, two variations were fabricated. The first was a dual-material phantom, the Doublet. Fibroglandular tissue and skin were represented by the most radiographically dense material available; adipose tissue was represented by the least radiographically dense material. The second variation, the Singlet, was fabricated with a single material to represent fibroglandular tissue and skin. It was subsequently filled with adipose-equivalent materials including oil, beeswax, and permanent urethane-based polymer. Simulated microcalcification clusters were further included in the phantoms via crushed eggshells. The phantoms were imaged and characterized visually and quantitatively. Results: The mammographic projections and tomosynthesis reconstructed images of the fabricated phantoms yielded realistic breast background. The mammograms of the phantoms demonstrated close correlation with simulated mammographic projection images of the corresponding virtual phantoms. Furthermore, power-law descriptions of the phantom images were in general agreement with real human images. The Singlet approach offered more realistic contrast as compared to the Doublet approach, but at the expense of air bubbles and air pockets that formed during the filling process. Conclusions: The presented physical breast phantoms and their matching virtual breast phantoms offer realistic breast anatomy, patient variability, and ease of use, making them a potential candidate for performing both system quality control testing and virtual clinical trials.« less

Development and Application of Stable Phantoms for the Evaluation of Photoacoustic Imaging Instruments

PubMed Central

Bohndiek, Sarah E.; Bodapati, Sandhya; Van De Sompel, Dominique; Kothapalli, Sri-Rajasekhar; Gambhir, Sanjiv S.

2013-01-01

Photoacoustic imaging combines the high contrast of optical imaging with the spatial resolution and penetration depth of ultrasound. This technique holds tremendous potential for imaging in small animals and importantly, is clinically translatable. At present, there is no accepted standard physical phantom that can be used to provide routine quality control and performance evaluation of photoacoustic imaging instruments. With the growing popularity of the technique and the advent of several commercial small animal imaging systems, it is important to develop a strategy for assessment of such instruments. Here, we developed a protocol for fabrication of physical phantoms for photoacoustic imaging from polyvinyl chloride plastisol (PVCP). Using this material, we designed and constructed a range of phantoms by tuning the optical properties of the background matrix and embedding spherical absorbing targets of the same material at different depths. We created specific designs to enable: routine quality control; the testing of robustness of photoacoustic signals as a function of background; and the evaluation of the maximum imaging depth available. Furthermore, we demonstrated that we could, for the first time, evaluate two small animal photoacoustic imaging systems with distinctly different light delivery, ultrasound imaging geometries and center frequencies, using stable physical phantoms and directly compare the results from both systems. PMID:24086557

Modeling in vivo fluorescence of small animals using TracePro software

NASA Astrophysics Data System (ADS)

Leavesley, Silas; Rajwa, Bartek; Freniere, Edward R.; Smith, Linda; Hassler, Richard; Robinson, J. Paul

2007-02-01

The theoretical modeling of fluorescence excitation, emission, and propagation within living tissue has been a limiting factor in the development and calibration of in vivo small animal fluorescence imagers. To date, no definitive calibration standard, or phantom, has been developed for use with small animal fluorescence imagers. Our work in the theoretical modeling of fluorescence in small animals using solid modeling software is useful in optimizing the design of small animal imaging systems, and in predicting their response to a theoretical model. In this respect, it is also valuable in the design of a fluorescence phantom for use in in vivo small animal imaging. The use of phantoms is a critical step in the testing and calibration of most diagnostic medical imaging systems. Despite this, a realistic, reproducible, and informative phantom has yet to be produced for use in small animal fluorescence imaging. By modeling the theoretical response of various types of phantoms, it is possible to determine which parameters are necessary for accurately modeling fluorescence within inhomogenous scattering media such as tissue. Here, we present the model that has been developed, the challenges and limitations associated with developing such a model, and the applicability of this model to experimental results obtained in a commercial small animal fluorescence imager.

Abdo-Man: a 3D-printed anthropomorphic phantom for validating quantitative SIRT.

PubMed

Gear, Jonathan I; Cummings, Craig; Craig, Allison J; Divoli, Antigoni; Long, Clive D C; Tapner, Michael; Flux, Glenn D

2016-12-01

The use of selective internal radiation therapy (SIRT) is rapidly increasing, and the need for quantification and dosimetry is becoming more widespread to facilitate treatment planning and verification. The aim of this project was to develop an anthropomorphic phantom that can be used as a validation tool for post-SIRT imaging and its application to dosimetry. The phantom design was based on anatomical data obtained from a T1-weighted volume-interpolated breath-hold examination (VIBE) on a Siemens Aera 1.5 T MRI scanner. The liver, lungs and abdominal trunk were segmented using the Hermes image processing workstation. Organ volumes were then uploaded to the Delft Visualization and Image processing Development Environment for smoothing and surface rendering. Triangular meshes defining the iso-surfaces were saved as stereo lithography (STL) files and imported into the Autodesk® Meshmixer software. Organ volumes were subtracted from the abdomen and a removable base designed to allow access to the liver cavity. Connection points for placing lesion inserts and filling holes were also included. The phantom was manufactured using a Stratasys Connex3 PolyJet 3D printer. The printer uses stereolithography technology combined with ink jet printing. Print material is a solid acrylic plastic, with similar properties to polymethylmethacrylate (PMMA). Measured Hounsfield units and calculated attenuation coefficients of the material were shown to also be similar to PMMA. Total print time for the phantom was approximately 5 days. Initial scans of the phantom have been performed with Y-90 bremsstrahlung SPECT/CT, Y-90 PET/CT and Tc-99m SPECT/CT. The CT component of these images compared well with the original anatomical reference, and measurements of volume agreed to within 9 %. Quantitative analysis of the phantom was performed using all three imaging techniques. Lesion and normal liver absorbed doses were calculated from the quantitative images in three dimensions using the local deposition method. 3D printing is a flexible and cost-efficient technology for manufacture of anthropomorphic phantom. Application of such phantoms will enable quantitative imaging and dosimetry methodologies to be evaluated, which with optimisation could help improve outcome for patients.

Portable work zone barrier-"mobile barriers" mobile barrier trailer : final report, December 2009.

DOT National Transportation Integrated Search

2009-12-01

This work has focused on the fabrication and implementation of the MBT-1 Beam which is a : truck mounted, moveable, expandable beam that provides positive work zone protection : comparable to a fixed concrete barrier. It is specifically intended to e...

Methods for multi-material stereolithography

DOEpatents

Wicker, Ryan [El Paso, TX; Medina, Francisco [El Paso, TX; Elkins, Christopher [Redwood City, CA

2011-06-14

Methods and systems of stereolithography for building cost-efficient and time-saving multi-material, multi-functional and multi-colored prototypes, models and devices configured for intermediate washing and curing/drying is disclosed including: laser(s), liquid and/or platform level sensing system(s), controllable optical system(s), moveable platform(s), elevator platform(s), recoating system(s) and at least one polymer retaining receptacle. Multiple polymer retaining receptacles may be arranged in a moveable apparatus, wherein each receptacle is adapted to actively/passively maintain a uniform, desired level of polymer by including a recoating device and a material fill/remove system. The platform is movably accessible to the polymer retaining receptacle(s), elevator mechanism(s) and washing and curing/drying area(s) which may be housed in a shielded enclosure(s). The elevator mechanism is configured to vertically traverse and rotate the platform, thus providing angled building, washing and curing/drying capabilities. A horizontal traversing mechanism may be included to facilitate manufacturing between components of SL cabinet(s) and/or alternative manufacturing technologies.

SU-G-BRB-01: A Novel 3D Printed Patient-Specific Phantom for Spine SBRT Quality Assurance: Comparison of 3D Printing Techniques

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, S; Kim, M; Lee, M

Purpose: The novel 3 dimensional (3D)-printed spine quality assurance (QA) phantoms generated by two different 3D-printing technologies, digital light processing (DLP) and Polyjet, were developed and evaluated for spine stereotactic body radiation treatment (SBRT). Methods: The developed 3D-printed spine QA phantom consisted of an acrylic body and a 3D-printed spine phantom. DLP and Polyjet 3D printers using the high-density acrylic polymer were employed to produce spine-shaped phantoms based on CT images. To verify dosimetric effects, the novel phantom was made it enable to insert films between each slabs of acrylic body phantom. Also, for measuring internal dose of spine, 3D-printedmore » spine phantom was designed as divided laterally exactly in half. Image fusion was performed to evaluate the reproducibility of our phantom, and the Hounsfield unit (HU) was measured based on each CT image. Intensity-modulated radiotherapy plans to deliver a fraction of a 16 Gy dose to a planning target volume (PTV) based on the two 3D-printing techniques were compared for target coverage and normal organ-sparing. Results: Image fusion demonstrated good reproducibility of the fabricated spine QA phantom. The HU values of the DLP- and Polyjet-printed spine vertebrae differed by 54.3 on average. The PTV Dmax dose for the DLP-generated phantom was about 1.488 Gy higher than for the Polyjet-generated phantom. The organs at risk received a lower dose when the DLP technique was used than when the Polyjet technique was used. Conclusion: This study confirmed that a novel 3D-printed phantom mimicking a high-density organ can be created based on CT images, and that a developed 3D-printed spine phantom could be utilized in patient-specific QA for SBRT. Despite using the same main material, DLP and Polyjet yielded different HU values. Therefore, the printing technique and materials must be carefully chosen in order to accurately produce a patient-specific QA phantom.« less

Scattering and Diffraction of Elastodynamic Waves in a Concentric Cylindrical Phantom for MR Elastography

PubMed Central

Schwartz, Benjamin L.; Yin, Ziying; Yaşar, Temel K.; Liu, Yifei; Khan, Altaf A.; Ye, Allen Q.; Royston, Thomas J.; Magin, Richard L.

2016-01-01

Aim The focus of this paper is to report on the design and construction of a multiply connected phantom for use in magnetic resonance elasography (MRE)–an imaging technique that allows for the non-invasive visualization of the displacement field throughout an object from externally driven harmonic motion–as well as its inverse modeling with a closed-form analytic solution which is derived herein from first principles. Methods Mathematically, the phantom is described as two infinite concentric circular cylinders with unequal complex shear moduli, harmonically vibrated at the exterior surface in a direction along their common axis. Each concentric cylinder is made of a hydrocolloid with its own specific solute concentration. They are assembled in a multi-step process for which custom scaffolding was designed and built. A customized spin-echo based MR elastography sequence with a sinusoidal motion-sensitizing gradient was used for data acquisition on a 9.4 T Agilent small-animal MR scanner. Complex moduli obtained from the inverse model are used to solve the forward problem with a finite element method. Results Both complex shear moduli show a significant frequency dependence (p < 0.001) in keeping with previous work. Conclusion The novel multiply connected phantom and mathematical model are validated as a viable tool for MRE studies. Significance On a small enough scale much of physiology can be mathematically modeled with basic geometric shapes, e.g. a cylinder representing a blood vessel. This work demonstrates the possibility of elegant mathematical analysis of phantoms specifically designed and carefully constructed for biomedical MRE studies. PMID:26886963

SU-E-QI-06: Design and Initial Validation of a Precise Capillary Phantom to Test Perfusion Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wood, R; Iacobucci, G; Khobragade, P

2014-06-15

Purpose: To design a precise perfusion phantom mimicking capillaries of the brain vasculature which could be used to test various perfusion protocols and algorithms which generate perfusion maps. Methods: A perfusion phantom was designed in Solidworks and built using additive manufacturing. The phantom was an overall cylindrical shape of diameter and height 20mm and containing capillaries of 200μm or 300μm which were parallel and in contact making up the inside volume where flow was allowed. We created a flow loop using a peristaltic pump and contrast agent was injected manually. Digital Subtraction Angiographic images and low contrast images with conemore » beam CT were acquired after the contrast was injected. These images were analyzed by our own code in LabVIEW software and Time-Density Curve, MTT and TTP was calculated. Results: Perfused area was visible in the cone beam CT images; however, individual capillaries were not distinguishable. The Time-Density Curve acquired was accurate, sensitive and repeatable. The parameters MTT, and TTP offered by the phantom were very sensitive to slight changes in the TDC shape. Conclusion: We have created a robust calibrating model for evaluation of existing perfusion data analysis systems. This approach is extremely sensitive to changes in the flow due to the high temporal resolution and could be used as a golden standard to assist developers in calibrating and testing of imaging perfusion systems and software algorithms. Supported by NIH Grant: 2R01EB002873 and an equipment grant from Toshiba Medical Systems Corporation.« less

TH-CD-206-08: An Anthropopathic Deformable Phantom for Geometric and Dose Accumulation Accuracy Validation of Deformable Image Registration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liao, Y; Chen, H; Chen, J

2016-06-15

Purpose: To design and construct a three-dimensional (3D) anthropopathic abdominal phantom for evaluating deformable image registration (DIR) accuracy on images and dose deformation in adaptive radiation therapy (ART). Method: Organ moulds, including liver, kidney, spleen, stomach, vertebra and two metastasis tumors, are 3D printed using the contours from an ovarian cancer patient. The organ moulds are molded with deformable gels that made of different mixtures of polyvinyl chloride (PVC) and the softener dioctyl terephthalate. Gels with different densities are obtained by a polynomial fitting curve which describes the relation between the CT number and PVC-softener blending ratio. The rigid vertebrasmore » are constructed by moulding with white cement. The final abdominal phantom is assembled by arranging all the fabricated organs inside a hollow dummy according to their anatomies and sealed with deformable gel with averaged CT number of muscle and fat. Geometric and dosimetric landmarks are embedded inside the phantom for spatial accuracy and dose accumulation accuracy studies. Three DIR algorithms available in the open source DIR toolkit-DIRART, including the Demons, the Horn-Schunck and Lucas-Kanade method and the Level-Set Motion method, are tested using the constructed phantom. Results: Viscoelastic behavior is observed in the constructed deformable gel, which serves as an ideal material for the deformable phantom. The constructed abdominal phantom consists of highly realistic anatomy and the fabricated organs inside have close CT number to its reference patient. DIR accuracy studies conducted on the constructed phantom using three DIR approaches indicate that geometric accuracy of a DIR algorithm has achieved does not guarantee accuracy in dose accumulation. Conclusions: We have designed and constructed an anthropopathic abdominal deformable phantom with satisfactory elastic property, realistic organ density and anatomy. This physical phantom is recyclable and can be used for routine validations of DIR geometric accuracy and dose accumulation accuracy in ART. This work is supported in part by grant from VARIAN MEDICAL SYSTEMS INC, the National Natural Science Foundation of China (no 81428019 and no 81301940), the Guangdong Natural Science Foundation (2015A030313302) and the 2015 Pearl River S&T Nova Program of Guangzhou (201506010096).« less

Design and implementation of a head-and-neck phantom for system audit and verification of intensity-modulated radiation therapy.

PubMed

Webster, Gareth J; Hardy, Mark J; Rowbottom, Carl G; Mackay, Ranald I

2008-04-16

The head and neck is a challenging anatomic site for intensity-modulated radiation therapy (IMRT), requiring thorough testing of planning and treatment delivery systems. Ideally, the phantoms used should be anatomically realistic, have radiologic properties identical to those of the tissues concerned, and allow for the use of a variety of devices to verify dose and dose distribution in any target or normaltissue structure. A phantom that approaches the foregoing characteristics has been designed and built; its specific purpose is verification for IMRT treatments in the head-andneck region. This semi-anatomic phantom, HANK, is constructed of Perspex (Imperial Chemical Industries, London, U.K.) and provides for the insertion of heterogeneities simulating air cavities in a range of fixed positions. Chamber inserts are manufactured to incorporate either a standard thimble ionization chamber (0.125 cm3: PTW, Freiburg, Germany) or a smaller PinPoint chamber (0.015 cm3: PTW), and measurements can be made with either chamber in a range of positions throughout the phantom. Coronal films can also be acquired within the phantom, and additional solid blocks of Perspex allow for transverse films to be acquired within the head region. Initial studies using simple conventional head-and-neck plans established the reproducibility of the phantom and the measurement devices to within the setup uncertainty of +/- 0.5 mm. Subsequent verification of 9 clinical head-and-neck IMRT plans demonstrated the efficacy of the phantom in making a range of patient-specific dose measurements in regions of dosimetric and clinical interest. Agreement between measured values and those predicted by the Pinnacle3 treatment planning system (Philips Medical Systems, Andover, MA) was found to be generally good, with a mean error on the calculated dose to each point of +0.2% (range: -4.3% to +2.2%; n = 9) for the primary planning target volume (PTV), -0.1% (range: -1.5% to +2.0%; n = 8) for the nodal PTV, and +0.0% (range: -1.8% to +4.3%, n = 9) for the spinal cord. The suitability of the phantom for measuring combined dose distributions using radiographic film was also evaluated. The phantom has proved to be a valuable tool in the development and implementation of clinical head-and-neck IMRT, allowing for accurate verification of absolute dose and dose distributions in regions of clinical and dosimetric interest.

Development and evaluation of an end‐to‐end test for head and neck IMRT with a novel multiple‐dosimetric modality phantom

PubMed Central

Zakjevskii, Viatcheslav V.; Knill, Cory S.; Rakowski, Joseph. T.

2016-01-01

A comprehensive end‐to‐end test for head and neck IMRT treatments was developed using a custom phantom designed to utilize multiple dosimetry devices. Initial end‐to‐end test and custom H&N phantom were designed to yield maximum information in anatomical regions significant to H&N plans with respect to: (i) geometric accuracy, (ii) dosimetric accuracy, and (iii) treatment reproducibility. The phantom was designed in collaboration with Integrated Medical Technologies. The phantom was imaged on a CT simulator and the CT was reconstructed with 1 mm slice thickness and imported into Varian's Eclipse treatment planning system. OARs and the PTV were contoured with the aid of Smart Segmentation. A clinical template was used to create an eight‐field IMRT plan and dose was calculated with heterogeneity correction on. Plans were delivered with a TrueBeam equipped with a high definition MLC. Preliminary end‐to‐end results were measured using film, ion chambers, and optically stimulated luminescent dosimeters (OSLDs). Ion chamber dose measurements were compared to the treatment planning system. Films were analyzed with FilmQA Pro using composite gamma index. OSLDs were read with a MicroStar reader using a custom calibration curve. Final phantom design incorporated two axial and one coronal film planes with 18 OSLD locations adjacent to those planes as well as four locations for IMRT ionization chambers below inferior film plane. The end‐to‐end test was consistently reproducible, resulting in average gamma pass rate greater than 99% using 3%/3 mm analysis criteria, and average OSLD and ion chamber measurements within 1% of planned dose. After initial calibration of OSLD and film systems, the end‐to‐end test provides next‐day results, allowing for integration in routine clinical QA. Preliminary trials have demonstrated that our end‐to‐end is a reproducible QA tool that enables the ongoing evaluation of dosimetric and geometric accuracy of clinical head and neck treatments. PACS number(s): 87.55.Qr PMID:27074453

Area-variable capacitive microaccelerometer with force-balancing electrodes

NASA Astrophysics Data System (ADS)

Ha, Byeoungju; Lee, Byeungleul; Sung, Sangkyung; Choi, Sangon; Shinn, Meenam; Oh, Yong-Soo; Song, Ci M.

1997-11-01

A surface micromachined accelerometer which senses an inertial motion with an area variation and a force balancing electrodes is developed. The grid-type planar mass of a 7 micrometers thick polysilicon is supported by four thin beams and suspended above a silicon substrate with a 1.5 micrometers air gap. The motion sensing electrodes are formed on the substrate. The sensor is designed as an interdigital rib structure that has a differential capacitor arrangement. The moveable electrodes are mounted on the mass and the pairs of the stationary electrodes are patterned on the substrate. In the accelerometer that has comb-type movable electrodes, the mechanical stress and the electrical pulling effects between a moveable electrodes and the fixed electrodes occur. However this grid-type structure can have a large area variation in a small area relatively without stress and pulling, high sensitivity can be achieved. In order to improve the dynamic rang and a linearity, a pair of comb shape force-balancing electrodes are implemented on both sides of the mass. The force-balancing electrodes are made of the same layer as the mass and anchored on a silicon substrate. When acceleration is applied in the lateral direction, the difference of capacitance results from the area variation between the two capacitors and is measured using a charge amplifier. As AC coupled complimentary pick- off signals are applied in paris of stationary electrodes, the undesirable effects due to temperature and electrical noise are reduced effectively. The accelerometer has a sensitivity of 28mV/g and a bandwidth of DC-120Hz. A resolution of 3mg and a non-linearity of 1.3 percent is achieved for a measurement range of +/- 9 g.

CT dose equilibration and energy absorption in polyethylene cylinders with diameters from 6 to 55 cm

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Xinhua; Zhang, Da; Liu, Bob, E-mail: bliu7@mgh.harvard.edu

2015-06-15

Purpose: ICRU Report No. 87 Committee and AAPM Task Group 200 designed a three-sectional polyethylene phantom of 30 cm in diameter and 60 cm in length for evaluating the midpoint dose D{sub L}(0) and its rise-to-the-equilibrium curve H(L) = D{sub L}(0)/D{sub eq} from computed tomography (CT) scanning, where D{sub eq} is the equilibrium dose. To aid the use of the phantom in radiation dose assessment and to gain an understanding of dose equilibration and energy absorption in polyethylene, the authors evaluated the short (20 cm) to long (60 cm) phantom dose ratio with a polyethylene diameter of 30 cm, assessedmore » H(L) in polyethylene cylinders of 6–55 cm in diameters, and examined energy absorption in these cylinders. Methods: A GEANT4-based Monte Carlo program was used to simulate the single axial scans of polyethylene cylinders (diameters 6–55 cm and length 90 cm, as well as diameter 30 cm and lengths 20 and 60 cm) on a clinical CT scanner (Somatom Definition dual source CT, Siemens Healthcare). Axial dose distributions were computed on the phantom central and peripheral axes. An average dose over the central 23 or 100 mm region was evaluated for modeling dose measurement using a 0.6 cm{sup 3} thimble chamber or a 10 cm long pencil ion chamber, respectively. The short (20 cm) to long (90 cm) phantom dose ratios were calculated for the 30 cm diameter polyethylene phantoms scanned at four tube voltages (80–140 kV) and a range of beam apertures (1–25 cm). H(L) was evaluated using the dose integrals computed with the 90 cm long phantoms. The resultant H(L) data were subsequently used to compute the fraction of the total energy absorbed inside or outside the scan range (E{sub in}/E or E{sub out}/E) on the phantom central and peripheral axes, where E = LD{sub eq} was the total energy absorbed along the z axis. Results: The midpoint dose in the 60 cm long polyethylene phantom was equal to that in the 90 cm long polyethylene phantom. The short-to-long phantom dose ratios changed with beam aperture and phantom axis but were insensitive to tube voltage. H(L) was insensitive to tube voltage and CT scanner model. As phantom diameter increased from 6 to 55 cm, E{sub in}/E generally decreased but asymptotically approached constant levels on the peripheral axes of large phantoms. The curve of E{sub in}/E versus scan length was almost identical to that of H(L). Similarly, E{sub out}/E increased with scan length and asymptotically approached the equilibrium for large scan lengths. E{sub out}/D{sub eq} was much less than the equilibrium length L{sub eq} where H(L) = 0.98, even with scan lengths much larger than L{sub eq}. Conclusions: The polyethylene phantom designed by ICRU Report No. 87 Committee and AAPM Task Group 200 is adequately long for assessing the midpoint dose and its equilibration in CT scanning. The short-to-long phantom dose ratios and the H(L) data provided in this paper allow easy evaluations of the midpoint dose, longitudinal dose distribution, and energy absorption in polyethylene phantoms. The results of dose equilibration and energy absorption presented herein may be insightful for the clinical CT scans with various subject sizes and scan lengths.« less

Fluid Dynamics of the Generation and Transmission of Heart Sounds: (1) A Cardiothoracic Phantom Based Study of Aortic Stenosis Murmurs

NASA Astrophysics Data System (ADS)

Bakhshaee, Hani; Seo, Jung-Hee; Zhu, Chi; Welsh, Nathaniel; Garreau, Guillaume; Tognetti, Gaspar; Andreou, Andreas; Mittal, Rajat

2015-11-01

A novel and versatile cardiothoracic phantom has been designed to study the biophysics of heart murmurs associated with aortic stenosis. The key features of the cardiothoracic phantom include the use of tissue-mimetic gel to model the sound transmission through the thorax and the embedded fluid circuit that is designed to mimic the heart sound mechanisms in large vessels with obstructions. The effect of the lungs on heart murmur propagation can also be studied through the insertion of lung-mimicking material into gel. Sounds on the surface of the phantom are measured using a variety of sensors and the spectrum of the recorded signal and the streamwise variation in total signal strength is recorded. Based on these results, we provide insights into the biophysics of heart murmurs and the effect of lungs on sound propagation through the thorax. Data from these experiments is also used to validate the results of a companion computational study. Authors want to acknowledge the financial supports for this study by SCH grant (IIS 1344772) from National Science Foundation.

Concept design and simulation study on a "phantom" anvil for circular stapler.

PubMed

Rulli, Francesco; Kartheuser, Alex; Amirhassankhani, Sasan; Mourad, Michel; Stefani, Mario; de Ferrá Aureli, Andrés; Sileri, Pierpaolo; Valentini, Pier Paolo

2015-04-01

Complications and challenges arising from the intraoperative double-stapling technique are seldom reported in colorectal surgery literature. Partial or full-thickness rectal injuries can occur during the introduction and the advancement of the circular stapler along the upper rectum. The aim of this study is to address some of these issues by designing and optimizing a "phantom" anvil manufactured to overcome difficulties throughout the rectal introduction and advancement of the circular stapler for the treatment of benign and malignant colon disease. The design of the "phantom" anvil has been performed using computer-aided modeling techniques, finite element investigations, and 2 essential keynotes in mind. The first one is the internal shape of the anvil, which is used for the connection to the gun. The second is the shape of the cap, which makes possible the insertion of the gun through the rectum. The "phantom" anvil has 2 functional requirements, which have been taken into account. The design has been optimized to avoid colorectal injuries, neoplastic dissemination (ie, mechanical seeding) and to reduce the fecal contamination. Numerical simulations show that a right combination of both top and bottom fillet radii of the shape of the anvil can reduce the stress for the considered anatomic configuration of >90%. Both the fillet radii at the top and the bottom of the device influence the local stress of the colon rectum. A dismountable device, which is used only for the insertion and advancement of the stapler, allows a dedicated design of its shape, keeping the remainder of the stapler unmodified. Computer-aided simulations are useful to perform numerical investigations to optimize the design of this auxiliary part for both the safety of the patient and the ease of the stapler advancement through the rectum.

Virtual phantom magnetic resonance imaging (ViP MRI) on a clinical MRI platform.

PubMed

Saint-Jalmes, Hervé; Bordelois, Alejandro; Gambarota, Giulio

2018-01-01

The purpose of this study was to implement Virtual Phantom Magnetic Resonance Imaging (ViP MRI), a technique that allows for generating reference signals in MR images using radiofrequency (RF) signals, on a clinical MR system and to test newly designed virtual phantoms. MRI experiments were conducted on a 1.5 T MRI scanner. Electromagnetic modelling of the ViP system was done using the principle of reciprocity. The ViP RF signals were generated using a compact waveform generator (dimensions of 26 cm × 18 cm × 16 cm), connected to a homebuilt 25 mm-diameter RF coil. The ViP RF signals were transmitted to the MRI scanner bore, simultaneously with the acquisition of the signal from the object of interest. Different types of MRI data acquisition (2D and 3D gradient-echo) as well as different phantoms, including the Shepp-Logan phantom, were tested. Furthermore, a uniquely designed virtual phantom - in the shape of a grid - was generated; this newly proposed phantom allows for the investigations of the vendor distortion correction field. High quality MR images of virtual phantoms were obtained. An excellent agreement was found between the experimental data and the inverse cube law, which was the expected functional dependence obtained from the electromagnetic modelling of the ViP system. Short-term time stability measurements yielded a coefficient of variation in the signal intensity over time equal to 0.23% and 0.13% for virtual and physical phantom, respectively. MR images of the virtual grid-shaped phantom were reconstructed with the vendor distortion correction; this allowed for a direct visualization of the vendor distortion correction field. Furthermore, as expected from the electromagnetic modelling of the ViP system, a very compact coil (diameter ~ cm) and very small currents (intensity ~ mA) were sufficient to generate a signal comparable to that of physical phantoms in MRI experiments. The ViP MRI technique was successfully implemented on a clinical MR system. One of the major advantages of ViP MRI over previous approaches is that the generation and transmission of RF signals can be achieved with a self-contained apparatus. As such, the ViP MRI technique is transposable to different platforms (preclinical and clinical) of different vendors. It is also shown here that ViP MRI could be used to generate signals whose characteristics cannot be reproduced by physical objects. This could be exploited to assess MRI system properties, such as the vendor distortion correction field. © 2017 American Association of Physicists in Medicine.

SU-E-T-52: A New Device for Quality Assurance of a Single Isocenter Technique for the Simultaneous Treatment of Multiple Brain Metastases

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maurer, J; Sintay, B; Varchena, V

2015-06-15

Purpose: Comprehensive quality assurance (QA) of a single isocenter technique for the simultaneous treatment of multiple brain metastases is presently impractical due to the time consuming nature of measuring each lesion’s dose on film or with a micro-chamber. Three dimensional diode array and full field film measurements are sometimes used to evaluate these plans, but gamma analysis may not reveal local errors that have significant effects on one or a few of several targets. This work aimed to design, build and test a phantom to simplify comprehensive measurement and evaluation. Methods: A phantom was designed with 28 stackable slabs. Themore » top and bottom slabs are 1.5 centimeters (cm) in thickness, and central 26 slabs are 0.5 cm thick. When assembled with radiochromic film in all 27 gaps, the phantom measures 16.5 x 15 x 19 cm. Etchings were designed to aide in identification of specific film planes on computed tomography (CT) images and correlation of individual PTVs with closest bisecting planes. Patient verification plans with a total of 16 PTVs were calculated on the phantom CT, and test deliveries both with and without couch kicks were performed to test the ability to identify correct film placements and subsequent PTV specific dose distributions on the films. Results: Bisecting planes corresponding to PTV locations were easily identified, and PTV specific dose distributions were clear for all 16 targets. For deliveries with couch kicks, the phantom PTV dose distributions closely approximated those calculated on the patient’s CT. For deliveries without couch kicks, PTV specific dosimetry was also possible, although the distributions had ‘ghosts’ equaling the number of couch kicks, with distance between ghosts increasing with distance from the isocenter. Conclusion: A new phantom facilitates fast comprehensive commissioning validation and PTV specific dosimetry for a single isocenter technique for treating multiple brain metastases. This work was partially funded by CIRS, Inc.« less

Scott Fitzgerald: famous writer, alcoholism and probable epilepsy.

PubMed

Wolski, Mariana M; Paola, Luciano de; Teive, Hélio A G

2017-01-01

Scott Fitzgerald, a world-renowned American writer, suffered from various health problems, particularly alcohol dependence, and died suddenly at the age of 44. According to descriptions in A Moveable Feast, by Ernest Hemingway, Fitzgerald had episodes resembling complex partial seizures, raising the possibility of temporal lobe epilepsy.

Marketing Books in the School Library.

ERIC Educational Resources Information Center

Langhorne, Mary Jo

1987-01-01

Circulation increased and student attitudes toward paperback books in a junior high school library media center collection improved when chain bookstore marketing techniques were used, i.e., topical arrangement; high visibility; clear, colorful labels; books shelved face out; and moveable display racks. These techniques are recommended with some…

The design and dosimetric evaluation of tannin-based Rhizophora spp. particleboards as phantoms for high energy photons and electrons

NASA Astrophysics Data System (ADS)

Yusof, M. F. Mohd; Abdullah, R.; Tajuddin, A. A.; Hashim, R.; Bauk, S.; Hamid, P. N. K. Abd

2018-01-01

A set of phantom with an external dimension of 30 cm x 30 cm was constructed from tannin-based Rhizophora spp. particleboards similar to the solid water phantoms. The dosimetric characteristics of the particleboard phantoms were evaluated at high energy photons and electrons by measuring the beam output at 6 MV photons and 6 MeV electrons based on the IAEA TRS 398:2000 protocol. The tissue-phantom ratio (TPR20,10) was measured at 6 and 10 MV photons. The beam output calibration of the particleboards was in good agreement to water and solid water phantoms at 6 MV photons with percentage difference of 1.7 and 6.2% respectively. The beam output calibration of the tannin-based Rhizophora spp. particleboards at 6 MeV electrons on the other hand were in excellent agreement to water with percentage difference of 0.3. The percentage depth dose of tannin-based Rhizophora spp. particleboards were in agreement to water and solid water within 4.5% when measured using ionization chamber and EBT2 film. The electron beam parameters of R50, R80 and R90 at 6 MeV electrons also were in good agreement to water and solid water phantoms. The overall results had indicated the suitability of tannin-based Rhizophora spp. particleboards as water substitute phantom materials for high energy photons and electrons.

Spiral Flow Phantom for Ultrasound Flow Imaging Experimentation.

PubMed

Yiu, Billy Y S; Yu, Alfred C H

2017-12-01

As new ultrasound flow imaging methods are being developed, there is a growing need to devise appropriate flow phantoms that can holistically assess the accuracy of the derived flow estimates. In this paper, we present a novel spiral flow phantom design whose Archimedean spiral lumen naturally gives rise to multi-directional flow over all possible angles (i.e., from 0° to 360°). Developed using lost-core casting principles, the phantom geometry comprised a three-loop spiral (4-mm diameter and 5-mm pitch), and it was set to operate in steady flow mode (3 mL/s flow rate). After characterizing the flow pattern within the spiral vessel using computational fluid dynamics (CFD) simulations, the phantom was applied to evaluate the performance of color flow imaging (CFI) and high-frame-rate vector flow imaging. Significant spurious coloring artifacts were found when using CFI to visualize flow in the spiral phantom. In contrast, using vector flow imaging (least-squares multi-angle Doppler based on a three-transmit and three-receive configuration), we observed consistent depiction of flow velocity magnitude and direction within the spiral vessel lumen. The spiral flow phantom was also found to be a useful tool in facilitating demonstration of dynamic flow visualization based on vector projectile imaging. Overall, these results demonstrate the spiral flow phantom's practical value in analyzing the efficacy of ultrasound flow estimation methods.

KSC-07pd2867

NASA Image and Video Library

2007-10-01

KENNEDY SPACE CENTER, FLA. -- In the Space Station Processing Facility at NASA's Kennedy Space Center, the starboard arm of the Special Purpose Dexterous Manipulator, known as Dextre, is moved toward the base, in the background. The arm will be installed on the base. Dextre is a sophisticated dual-armed robot, which is part of Canada's contribution to the International Space Station (ISS). Along with Canadarm2, whose technical name is the Space Station Remote Manipulator System, and a moveable work platform called the Mobile Base System, these three elements form a robotic system called the Mobile Servicing System, or MSS. The three components have been designed to work together or independently. Dextre is part of the payload scheduled on mission STS-123, targeted to launch Feb. 14. Photo credit: NASA/George Shelton

KSC-07pd2869

NASA Image and Video Library

2007-10-01

KENNEDY SPACE CENTER, FLA. -- In the Space Station Processing Facility at NASA's Kennedy Space Center, technicians aid with the lowering of the starboard arm of the Special Purpose Dexterous Manipulator, known as Dextre, toward the base. The arm will be installed on the base. Dextre is a sophisticated dual-armed robot, which is part of Canada's contribution to the International Space Station (ISS). Along with Canadarm2, whose technical name is the Space Station Remote Manipulator System, and a moveable work platform called the Mobile Base System, these three elements form a robotic system called the Mobile Servicing System, or MSS. The three components have been designed to work together or independently. Dextre is part of the payload scheduled on mission STS-123, targeted to launch Feb. 14. Photo credit: NASA/George Shelton

KSC-07pd2864

NASA Image and Video Library

2007-10-01

KENNEDY SPACE CENTER, FLA. -- In the Space Station Processing Facility at NASA's Kennedy Space Center, technicians adjust the cables of an overhead crane on the starboard arm of the Special Purpose Dexterous Manipulator, known as Dextre. The arm will be moved to and installed on the base. Dextre is a sophisticated dual-armed robot, which is part of Canada's contribution to the International Space Station ISS. Along with Canadarm2, whose technical name is the Space Station Remote Manipulator System, and a moveable work platform called the Mobile Base System, these three elements form a robotic system called the Mobile Servicing System, or MSS. The three components have been designed to work together or independently. Dextre is part of the payload scheduled on mission STS-123, targeted to launch Feb. 14. Photo credit: NASA/George Shelton

KSC-07pd2865

NASA Image and Video Library

2007-10-01

KENNEDY SPACE CENTER, FLA. -- In the Space Station Processing Facility at NASA's Kennedy Space Center, technicians begin raising the starboard arm of the Special Purpose Dexterous Manipulator, known as Dextre, for its move across the facility. The arm will be installed on the base. Dextre is a sophisticated dual-armed robot, which is part of Canada's contribution to the International Space Station ISS. Along with Canadarm2, whose technical name is the Space Station Remote Manipulator System, and a moveable work platform called the Mobile Base System, these three elements form a robotic system called the Mobile Servicing System, or MSS. The three components have been designed to work together or independently. Dextre is part of the payload scheduled on mission STS-123, targeted to launch Feb. 14. Photo credit: NASA/George Shelton

KSC-08pd0605

NASA Image and Video Library

2008-02-11

KENNEDY SPACE CENTER, FLA. -- In the Space Station Processing Facility at NASA's Kennedy Space Center, the Special Purpose Dexterous Manipulator, known as Dextre, moves across the facility via an overhead crane to the payload canister at right for transfer to Launch Pad 39A. Dextre is a sophisticated dual-armed robot, which is part of Canada's contribution to the International Space Station. Along with Canadarm2, which is called the Space Station Remote Manipulator System, and a moveable work platform called the Mobile Base System, these three elements form a robotic system called the Mobile Servicing System. The three components have been designed to work together or independently. Dextre is part of the payload on space shuttle Endeavour's STS-123 mission, targeted for launch March 11. Photo courtesy of The Boeing Company

Hybrid computational phantoms of the 15-year male and female adolescent: Applications to CT organ dosimetry for patients of variable morphometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Choonsik; Lodwick, Daniel; Williams, Jonathan L.

Currently, two classes of the computational phantoms have been developed for dosimetry calculation: (1) stylized (or mathematical) and (2) voxel (or tomographic) phantoms describing human anatomy through mathematical surface equations and three-dimensional labeled voxel matrices, respectively. Mathematical surface equations in stylized phantoms provide flexibility in phantom design and alteration, but the resulting anatomical description is, in many cases, not very realistic. Voxel phantoms display far better anatomical realism, but they are limited in terms of their ability to alter organ shape, position, and depth, as well as body posture. A new class of computational phantoms - called hybrid phantoms -more » takes advantage of the best features of stylized and voxel phantoms - flexibility and anatomical realism, respectively. In the current study, hybrid computational phantoms representing reference 15-year male and female body anatomy and anthropometry are presented. For the male phantom, organ contours were extracted from the University of Florida (UF) 14-year series B male voxel phantom, while for the female phantom, original computed tomography (CT) data from two 14-year female patients were used. Polygon mesh models for the major organs and tissues were reconstructed for nonuniform rational B-spline (NURBS) surface modeling. The resulting NURBS/polygon mesh models representing body contour and internal anatomy were matched to anthropometric data and reference organ mass data provided by the Centers for Disease Control and Prevention (CDC) and the International Commission on Radiation Protection (ICRP), respectively. Finally, two hybrid 15-year male and female phantoms were completed where a total of eight anthropometric data categories were matched to standard values within 4% and organ masses matched to ICRP data within 1% with the exception of total skin. To highlight the flexibility of the hybrid phantoms, 10th and 90th weight percentile 15-year male and female phantoms were further developed from the 50th percentile phantoms through adjustments in the body contour to match the total body masses given in CDC pediatric growth curves. The resulting six NURBS phantoms, male and female phantoms representing their 10th, 50th, and 90th weight percentiles, were used to investigate the influence of body fat distributions on internal organ doses following CT imaging. The phantoms were exposed to multislice chest and abdomen helical CT scans, and in-field organ absorbed doses were calculated. The results demonstrated that the use of traditional stylized phantoms yielded organ dose estimates that deviate from those given by the UF reference hybrid phantoms by up to a factor of 2. The study also showed that use of reference, or 50th percentile, phantoms to assess organ doses in underweight 15-year-old children would not lead to significant organ dose errors (typically less than 10%). However, more significant errors were noted (up to {approx}30%) when reference phantoms are used to represent overweight children in CT imaging dosimetry. These errors are expected to only further increase as one considers CT organ doses in overweight and obese individuals of the adult patient population, thus emphasizing the advantages of patient-sculptable phantom technology.« less

A phantom for quantitation of partial volume effects in ECT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mullani, N.A.

1989-02-01

A special phantom has been designed, built and tested to measure the quantitative recovery of ECT data from the heart as a function of the size of the object and the angulation of a 1 cm thick simulated myocardium inclined with respect to the image plane. The phantom consists of five objects of 0.5, 1.0, 1.5. 2.0, and 3.0 cm width and six 1 cm thick strips inclined at 0, 30, 45, 60, 90, and -90 degrees with respect to the axial direction. Recovery coefficients for different object sizes and simulated 1 cm thick myocardium inclined at different angles canmore » be obtained from a single scan. Adequacy of axial sampling can be observed visually by creating the long axis view of the phantom.« less

Three-dimensional printing (3DP) of neonatal head phantom for ultrasound: thermocouple embedding and simulation of bone.

PubMed

Gatto, Matteo; Memoli, Gianluca; Shaw, Adam; Sadhoo, Neelaksh; Gelat, Pierre; Harris, Russell A

2012-09-01

A neonatal head phantom, comprising of an ellipsoidal geometry and including a circular aperture for simulating the fontanel was designed and fabricated, in order to allow an objective assessment of thermal rise in tissues during trans-cranial ultrasonic scanning of pre-term neonates. The precise position of a series of thermocouples was determined on the basis of finite-element analysis, which identified crucial target points for the thermal monitoring within the phantom geometry. Three-Dimensional Printing (3DP) was employed for the manufacture of the skull phantom, which was subsequently filled with dedicated brain-mimic material. A novel 3DP material combination was found to be able to mimic the acoustic properties of neonatal skull bone. Similarly, variations of a standard recipe for tissue mimic were examined, until one was found to mimic the brain of an infant. A specific strategy was successfully pursued to embed a thermocouple within the 3DP skull phantom during the manufacturing process. An in-process machine vision system was used to assess the correct position of the deposited thermocouple inside the fabricated skull phantom. An external silicone-made skin-like covering completed the phantom and was manufactured through a Direct Rapid Tooling (DRT) technique. Copyright © 2011 IPEM. Published by Elsevier Ltd. All rights reserved.

Biologically relevant photoacoustic imaging phantoms with tunable optical and acoustic properties

PubMed Central

Vogt, William C.; Jia, Congxian; Wear, Keith A.; Garra, Brian S.; Joshua Pfefer, T.

2016-01-01

Abstract. Established medical imaging technologies such as magnetic resonance imaging and computed tomography rely on well-validated tissue-simulating phantoms for standardized testing of device image quality. The availability of high-quality phantoms for optical-acoustic diagnostics such as photoacoustic tomography (PAT) will facilitate standardization and clinical translation of these emerging approaches. Materials used in prior PAT phantoms do not provide a suitable combination of long-term stability and realistic acoustic and optical properties. Therefore, we have investigated the use of custom polyvinyl chloride plastisol (PVCP) formulations for imaging phantoms and identified a dual-plasticizer approach that provides biologically relevant ranges of relevant properties. Speed of sound and acoustic attenuation were determined over a frequency range of 4 to 9 MHz and optical absorption and scattering over a wavelength range of 400 to 1100 nm. We present characterization of several PVCP formulations, including one designed to mimic breast tissue. This material is used to construct a phantom comprised of an array of cylindrical, hemoglobin-filled inclusions for evaluation of penetration depth. Measurements with a custom near-infrared PAT imager provide quantitative and qualitative comparisons of phantom and tissue images. Results indicate that our PVCP material is uniquely suitable for PAT system image quality evaluation and may provide a practical tool for device validation and intercomparison. PMID:26886681

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lujano, C; Hernandez, N; Keith, T

Purpose: To describe the proton phantoms that IROC Houston uses to approve and credential proton institutions to participate in NCI-sponsored clinical trials. Methods: Photon phantoms cannot necessarily be used for proton measurements because protons react differently than photons in some plastics. As such plastics that are tissue equivalent for protons were identified. Another required alteration is to ensure that the film dosimeters are housed in the phantom with no air gap to avoid proton streaming. Proton-equivalent plastics/materials used include RMI Solid Water, Techron HPV, blue water, RANDO soft tissue material, balsa wood, compressed cork and polyethylene. Institutions wishing to bemore » approved or credentialed request a phantom and are prioritized for delivery. At the institution, the phantom is imaged, a treatment plan is developed, positioned on the treatment couch and the treatment is delivered. The phantom is returned and the measured dose distributions are compared to the institution’s electronically submitted treatment plan dosimetry data. Results: IROC Houston has developed an extensive proton phantom approval/credentialing program consisting of five different phantoms designs: head, prostate, lung, liver and spine. The phantoms are made with proton equivalent plastics that have HU and relative stopping powers similar (within 5%) of human tissues. They also have imageable targets, avoidance structures, and heterogeneities. TLD and radiochromic film are contained in the target structures. There have been 13 head, 33 prostate, 18 lung, 2 liver and 16 spine irradiations with either passive scatter, or scanned proton beams. The pass rates have been: 100%, 69.7%, 72.2%, 50%, and 81.3%, respectively. Conclusion: IROC Houston has responded to the recent surge in proton facilities by developing a family of anthropomorphic phantoms that are able to be used for remote audits of proton beams. Work supported by PHS grant CA10953 and CA081647.« less

Ecosystem Food Web Lift-The-Flap Pages

ERIC Educational Resources Information Center

Atwood-Blaine, Dana; Rule, Audrey C.; Morgan, Hannah

2016-01-01

In the lesson on which this practical article is based, third grade students constructed a "lift-the-flap" page to explore food webs on the prairie. The moveable papercraft focused student attention on prairie animals' external structures and how the inferred functions of those structures could support further inferences about the…

People Who Study Higher Education

ERIC Educational Resources Information Center

Harland, Tony

2009-01-01

The study of higher education can seem extraordinarily complex because what counts as knowledge is contestable and the higher education research community is, like Hemingway's Paris, a moveable feast. A lack of epistemological precision and field uncertainty is partly due to the fact that those who study higher education tend to work in higher…

78 FR 66266 - Drawbridge Operation Regulation; Atlantic Intracoastal Waterway (AIWW), Chesapeake, VA

Federal Register 2010, 2011, 2012, 2013, 2014

2013-11-05

... deviation from the operating schedule that governs the I64 Bridge across the Atlantic Intracoastal Waterway... deviation, call or email Mrs. Kashanda Booker, Bridge Administration Branch Fifth District, Coast Guard... maintenance of the moveable spans on the structure. The current operating schedule for the drawbridge is set...

76 FR 63840 - Drawbridge Operation Regulation; Corson Inlet, Strathmere, NJ

Federal Register 2010, 2011, 2012, 2013, 2014

2011-10-14

... during the project while the railings on the moveable span portion of the bridge are replaced. DATES... deviation from the regulations governing the operation of the Corson Inlet Bridge (County Route 619), at.... SUPPLEMENTARY INFORMATION: The Cape May County Bridge Commission, who owns and operates this bascule drawbridge...

77 FR 420 - Drawbridge Operation Regulation; Corson Inlet, Stathmere, NJ

Federal Register 2010, 2011, 2012, 2013, 2014

2012-01-05

... the course of the project, while the railings on the moveable span portion of the bridge are replaced... deviation from the regulations governing the operation of the Corson Inlet Bridge (County Route 619), across... INFORMATION: The Cape May County Bridge Commission, who owns and operates this bascule drawbridge, has...

Next Generation Enterprise Network: Navy Implementing Revised Approach, but Improvement Needed in Mitigating Risks

DTIC Science & Technology

2012-09-01

Hewlett Packard Enterprise Services) that ended in September 2010.2 To bridge the time between the end of the NMCI contract and the full transition to...some leasehold improvements; and moveable infrastructure associated with local network operations. Award contract for transport services and

75 FR 38712 - Drawbridge Operation Regulation; Shrewsbury River, NJ

Federal Register 2010, 2011, 2012, 2013, 2014

2010-07-06

...) with respect to this rule because we are removing the operation regulations for a moveable draw bridge.... Protection of Children We have analyzed this rule under Executive Order 13045, Protection of Children from... create an environmental risk to health or risk to safety that might disproportionately affect children...

Pushability and frictional characteristics of medical instruments.

PubMed

Wünsche, P; Werner, C; Bloss, P

2002-01-01

A tensile testing equipment is combined with a torque module and a 3D force tranducer to characterize the pushability of catheter systems inside modular vessel phantoms. The modular construction of the phantom allows using two dimensional vessel shapes with different contours. Inside the phantom we put a tube or a guide catheter in which the instruments are pushed or redrawn in the presence of a liquid (water, blood, etc.) at body temperature. During pushing or redrawing we measure axial and rotational values. Additionally, friction forces and coefficients are separately determined by using a special designed friction module. First results are presented and discussed.

XDesign: an open-source software package for designing X-ray imaging phantoms and experiments.

PubMed

Ching, Daniel J; Gürsoy, Dogˇa

2017-03-01

The development of new methods or utilization of current X-ray computed tomography methods is impeded by the substantial amount of expertise required to design an X-ray computed tomography experiment from beginning to end. In an attempt to make material models, data acquisition schemes and reconstruction algorithms more accessible to researchers lacking expertise in some of these areas, a software package is described here which can generate complex simulated phantoms and quantitatively evaluate new or existing data acquisition schemes and image reconstruction algorithms for targeted applications.

XDesign: An open-source software package for designing X-ray imaging phantoms and experiments

DOE PAGES

Ching, Daniel J.; Gursoy, Dogˇa

2017-02-21

Here, the development of new methods or utilization of current X-ray computed tomography methods is impeded by the substantial amount of expertise required to design an X-ray computed tomography experiment from beginning to end. In an attempt to make material models, data acquisition schemes and reconstruction algorithms more accessible to researchers lacking expertise in some of these areas, a software package is described here which can generate complex simulated phantoms and quantitatively evaluate new or existing data acquisition schemes and image reconstruction algorithms for targeted applications.

Cerebral NIRS performance testing with molded and 3D-printed phantoms (Conference Presentation)

NASA Astrophysics Data System (ADS)

Wang, Jianting; Huang, Stanley; Chen, Yu; Welle, Cristin G.; Pfefer, T. Joshua

2017-03-01

Near-infrared spectroscopy (NIRS) has emerged as a low-cost, portable approach for rapid, point-of-care detection of hematomas caused by traumatic brain injury. As a new technology, there is a need to develop standardized test methods for objective, quantitative performance evaluation of these devices. Towards this goal, we have developed and studied two types of phantom-based testing approaches. The first involves 3D-printed phantoms incorporating hemoglobin-filled inclusions. Phantom layers representing specific cerebral tissues were printed using photopolymers doped with varying levels of titanium oxide and black resin. The accuracy, precision and spectral dependence of printed phantom optical properties were validated using spectrophotometry. The phantom also includes a hematoma inclusion insert which was filled with a hemoglobin solution. Oxygen saturation levels were modified by adding sodium dithionite at calibrated concentrations. The second phantom approach involves molded silicone layers with a superficial region - simulating the scalp and skull - comprised of removable layers to vary hematoma size and depth, and a bottom layer representing brain matter. These phantoms were tested with both a commercial hematoma detector and a custom NIRS system to optimize their designs and validate their utility in performing inter-device comparisons. The effects of hematoma depth, diameter, and height, as well as tissue optical properties and biological variables including hemoglobin saturation level and scalp/skull thickness were studied. Results demonstrate the ability to quantitatively compare NIRS device performance and indicate the promise of using 3D printing to achieve phantoms with realistic variations in tissue optical properties for evaluating biophotonic device performance.

Poly(vinyl alcohol) cryogel phantoms for use in ultrasound and MR imaging

NASA Astrophysics Data System (ADS)

Surry, K. J. M.; Austin, H. J. B.; Fenster, A.; Peters, T. M.

2004-12-01

Poly(vinyl alcohol) cryogel, PVA-C, is presented as a tissue-mimicking material, suitable for application in magnetic resonance (MR) imaging and ultrasound imaging. A 10% by weight poly(vinyl alcohol) in water solution was used to form PVA-C, which is solidified through a freeze-thaw process. The number of freeze-thaw cycles affects the properties of the material. The ultrasound and MR imaging characteristics were investigated using cylindrical samples of PVA-C. The speed of sound was found to range from 1520 to 1540 m s-1, and the attenuation coefficients were in the range of 0.075-0.28 dB (cm MHz)-1. T1 and T2 relaxation values were found to be 718-1034 ms and 108-175 ms, respectively. We also present applications of this material in an anthropomorphic brain phantom, a multi-volume stenosed vessel phantom and breast biopsy phantoms. Some suggestions are made for how best to handle this material in the phantom design and development process.

Results from a Prototype Proton-CT Head Scanner

NASA Astrophysics Data System (ADS)

Johnson, R. P.; Bashkirov, V. A.; Coutrakon, G.; Giacometti, V.; Karbasi, P.; Karonis, N. T.; Ordoñez, C. E.; Pankuch, M.; Sadrozinski, H. F.-W.; Schubert, K. E.; Schulte, R. W.

We are exploring low-dose proton radiography and computed tomography (pCT) as techniques to improve the accuracy of proton treatment planning and to provide artifact-free images for verification and adaptive therapy at the time of treatment. Here we report on comprehensive beam test results with our prototype pCT head scanner. The detector system and data acquisition attain a sustained rate of more than a million protons individually measured per second, allowing a full CT scan to be completed in six minutes or less of beam time. In order to assess the performance of the scanner for proton radiography as well as computed tomography, we have performed numerous scans of phantoms at the Northwestern Medicine Chicago Proton Center including a custom phantom designed to assess the spatial resolution, a phantom to assess the measurement of relative stopping power, and a dosimetry phantom. Some images, performance, and dosimetry results from those phantom scans are presented together with a description of the instrument, the data acquisition system, and the calibration methods.

Hybrid computational phantoms of the male and female newborn patient: NURBS-based whole-body models

NASA Astrophysics Data System (ADS)

Lee, Choonsik; Lodwick, Daniel; Hasenauer, Deanna; Williams, Jonathan L.; Lee, Choonik; Bolch, Wesley E.

2007-07-01

Anthropomorphic computational phantoms are computer models of the human body for use in the evaluation of dose distributions resulting from either internal or external radiation sources. Currently, two classes of computational phantoms have been developed and widely utilized for organ dose assessment: (1) stylized phantoms and (2) voxel phantoms which describe the human anatomy via mathematical surface equations or 3D voxel matrices, respectively. Although stylized phantoms based on mathematical equations can be very flexible in regard to making changes in organ position and geometrical shape, they are limited in their ability to fully capture the anatomic complexities of human internal anatomy. In turn, voxel phantoms have been developed through image-based segmentation and correspondingly provide much better anatomical realism in comparison to simpler stylized phantoms. However, they themselves are limited in defining organs presented in low contrast within either magnetic resonance or computed tomography images—the two major sources in voxel phantom construction. By definition, voxel phantoms are typically constructed via segmentation of transaxial images, and thus while fine anatomic features are seen in this viewing plane, slice-to-slice discontinuities become apparent in viewing the anatomy of voxel phantoms in the sagittal or coronal planes. This study introduces the concept of a hybrid computational newborn phantom that takes full advantage of the best features of both its stylized and voxel counterparts: flexibility in phantom alterations and anatomic realism. Non-uniform rational B-spline (NURBS) surfaces, a mathematical modeling tool traditionally applied to graphical animation studies, was adopted to replace the limited mathematical surface equations of stylized phantoms. A previously developed whole-body voxel phantom of the newborn female was utilized as a realistic anatomical framework for hybrid phantom construction. The construction of a hybrid phantom is performed in three steps: polygonization of the voxel phantom, organ modeling via NURBS surfaces and phantom voxelization. Two 3D graphic tools, 3D-DOCTOR™ and Rhinoceros™, were utilized to polygonize the newborn voxel phantom and generate NURBS surfaces, while an in-house MATLAB™ code was used to voxelize the resulting NURBS model into a final computational phantom ready for use in Monte Carlo radiation transport calculations. A total of 126 anatomical organ and tissue models, including 38 skeletal sites and 31 cartilage sites, were described within the hybrid phantom using either NURBS or polygon surfaces. A male hybrid newborn phantom was constructed following the development of the female phantom through the replacement of female-specific organs with male-specific organs. The outer body contour and internal anatomy of the NURBS-based phantoms were adjusted to match anthropometric and reference newborn data reported by the International Commission on Radiological Protection in their Publication 89. The voxelization process was designed to accurately convert NURBS models to a voxel phantom with minimum volumetric change. A sensitivity study was additionally performed to better understand how the meshing tolerance and voxel resolution would affect volumetric changes between the hybrid-NURBS and hybrid-voxel phantoms. The male and female hybrid-NURBS phantoms were constructed in a manner so that all internal organs approached their ICRP reference masses to within 1%, with the exception of the skin (-6.5% relative error) and brain (-15.4% relative error). Both hybrid-voxel phantoms were constructed with an isotropic voxel resolution of 0.663 mm—equivalent to the ICRP 89 reference thickness of the newborn skin (dermis and epidermis). Hybrid-NURBS phantoms used to create their voxel counterpart retain the non-uniform scalability of stylized phantoms, while maintaining the anatomic realism of segmented voxel phantoms with respect to organ shape, depth and inter-organ positioning. This work was supported by the National Cancer Institute.

Design and Development of a Telerehabilitation Platform for Patients With Phantom Limb Pain: A User-Centered Approach

PubMed Central

2017-01-01

Background Phantom limb pain is a frequent and persistent problem following amputation. Achieving sustainable favorable effects on phantom limb pain requires therapeutic interventions such as mirror therapy that target maladaptive neuroplastic changes in the central nervous system. Unfortunately, patients’ adherence to unsupervised exercises is generally poor and there is a need for effective strategies such as telerehabilitation to support long-term self-management of patients with phantom limb pain. Objective The main aim of this study was to describe the user-centered approach that guided the design and development of a telerehabilitation platform for patients with phantom limb pain. We addressed 3 research questions: (1) Which requirements are defined by patients and therapists for the content and functions of a telerehabilitation platform and how can these requirements be prioritized to develop a first prototype of the platform? (2) How can the user interface of the telerehabilitation platform be designed so as to match the predefined critical user requirements and how can this interface be translated into a medium-fidelity prototype of the platform? (3) How do patients with phantom limb pain and their treating therapists judge the usability of the medium-fidelity prototype of the telerehabilitation platform in routine care and how can the platform be redesigned based on their feedback to achieve a high-fidelity prototype? Methods The telerehabilitation platform was developed using an iterative user-centered design process. In the first phase, a questionnaire followed by a semistructured interview was used to identify the user requirements of both the patients and their physical and occupational therapists, which were then prioritized using a decision matrix. The second phase involved designing the interface of the telerehabilitation platform using design sketches, wireframes, and interface mock-ups to develop a low-fidelity prototype. Heuristic evaluation resulted in a medium-fidelity prototype whose usability was tested in routine care in the final phase, leading to the development of a high-fidelity prototype. Results A total of 7 categories of patient requirements were identified: monitoring, exercise programs, communication, settings, background information, log-in, and general requirements. One additional category emerged for therapists: patient management. Based on these requirements, patient and therapist interfaces for the telerehabilitation platform were developed and redesigned by the software development team in an iterative process, addressing the usability problems that were reported by the users during 4 weeks of field testing in routine care. Conclusions Our findings underline the importance of involving the users and other stakeholders early and continuously in an iterative design process, as well as the need for clear criteria to identify critical user requirements. A decision matrix is presented that incorporates the views of various stakeholders in systematically rating and prioritizing user requirements. The findings and lessons learned might help health care providers, researchers, software designers, and other stakeholders in designing and evaluating new teletreatments, and hopefully increase the likelihood of user acceptance. PMID:28582249

Comparative power law analysis of structured breast phantom and patient images in digital mammography and breast tomosynthesis.

PubMed

Cockmartin, L; Bosmans, H; Marshall, N W

2013-08-01

This work characterizes three candidate mammography phantoms with structured background in terms of power law analysis in the low frequency region of the power spectrum for 2D (planar) mammography and digital breast tomosynthesis (DBT). The study was performed using three phantoms (spheres in water, Voxmam, and BR3D CIRS phantoms) on two DBT systems from two different vendors (Siemens Inspiration and Hologic Selenia Dimensions). Power spectra (PS) were calculated for planar projection, DBT projection, and reconstructed images and curve fitted in the low frequency region from 0.2 to 0.7 mm(-1) with a power law function characterized by an exponent β and magnitude κ. The influence of acquisition dose and tube voltage on the power law parameters was first explored. Then power law parameters were calculated from images acquired with the same anode∕filter combination and tube voltage for the three test objects, and compared with each other. Finally, PS curves for automatic exposure controlled acquisitions (anode∕filter combination and tube voltages selected by the systems based on the breast equivalent thickness of the test objects) were compared against PS analysis performed on patient data (for Siemens 80 and for Hologic 48 mammograms and DBT series). Dosimetric aspects of the three test objects were also examined. The power law exponent (β) was found to be independent of acquisition dose for planar mammography but varied more for DBT projections of the sphere-phantom. Systematic increase of tube voltage did not affect β but decreased κ, both in planar and DBT projection phantom images. Power spectra of the BR3D phantom were closer to those of the patients than these of the Voxmam phantom; the Voxmam phantom gave high values of κ compared to the other phantoms and the patient series. The magnitude of the PS curves of the BR3D phantom was within the patient range but β was lower than the average patient value. Finally, PS magnitude for the sphere-phantom coincided with the patient curves for Siemens but was lower for the Hologic system. Close agreement of doses for all three phantoms with patient doses was found. Power law parameters of the phantoms were close to those of the patients but no single phantom matched in terms of both magnitude (κ) and texture (β) for the x-ray systems in this work. PS analysis of structured phantoms is feasible and this methodology can be used to suggest improvements in phantom design.

A methodology for image quality evaluation of advanced CT systems.

PubMed

Wilson, Joshua M; Christianson, Olav I; Richard, Samuel; Samei, Ehsan

2013-03-01

This work involved the development of a phantom-based method to quantify the performance of tube current modulation and iterative reconstruction in modern computed tomography (CT) systems. The quantification included resolution, HU accuracy, noise, and noise texture accounting for the impact of contrast, prescribed dose, reconstruction algorithm, and body size. A 42-cm-long, 22.5-kg polyethylene phantom was designed to model four body sizes. Each size was represented by a uniform section, for the measurement of the noise-power spectrum (NPS), and a feature section containing various rods, for the measurement of HU and the task-based modulation transfer function (TTF). The phantom was scanned on a clinical CT system (GE, 750HD) using a range of tube current modulation settings (NI levels) and reconstruction methods (FBP and ASIR30). An image quality analysis program was developed to process the phantom data to calculate the targeted image quality metrics as a function of contrast, prescribed dose, and body size. The phantom fabrication closely followed the design specifications. In terms of tube current modulation, the tube current and resulting image noise varied as a function of phantom size as expected based on the manufacturer specification: From the 16- to 37-cm section, the HU contrast for each rod was inversely related to phantom size, and noise was relatively constant (<5% change). With iterative reconstruction, the TTF exhibited a contrast dependency with better performance for higher contrast objects. At low noise levels, TTFs of iterative reconstruction were better than those of FBP, but at higher noise, that superiority was not maintained at all contrast levels. Relative to FBP, the NPS of iterative reconstruction exhibited an ~30% decrease in magnitude and a 0.1 mm(-1) shift in the peak frequency. Phantom and image quality analysis software were created for assessing CT image quality over a range of contrasts, doses, and body sizes. The testing platform enabled robust NPS, TTF, HU, and pixel noise measurements as a function of body size capable of characterizing the performance of reconstruction algorithms and tube current modulation techniques.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jermoumi, M; Ngwa, W; Dana-Farber Cancer Institute, Brigham and Women's Hospital, Harvard Medical School, Boston, MA

Purpose: Use of Small Animal Radiation Research Platform (SARRP) systems for conducting state-of-the-art image guided radiotherapy (IGRT) research on small animals has become more common over the past years. The purpose of this work is to develop and test the suitability and performance of a comprehensive quality assurance (QA) phantom for the SARRP. Methods: A QA phantom was developed for carrying out daily, monthly and annual QA tasks including imaging, dosimetry and treatment planning system (TPS) performance evaluation of the SARRP. The QA phantom consists of nine (60×60×5 mm3) KV-energy tissue equivalent solid water slabs that can be employed formore » annual dosimetry QA with film. Three of the top slabs are replaceable with ones incorporating Mosfets or OSLDs arranged in a quincunx pattern, or a slab drilled to accommodate an ion chamber insert. These top slabs are designed to facilitate routine daily and monthly QA tasks such as output constancy, isocenter congruency test, treatment planning system (TPS) QA, etc. One slab is designed with inserts for image QA. A prototype of the phantom was applied to test the performance of the imaging, planning and treatment delivery systems. Results: Output constancy test results showed daily variations within 3%. For isocenter congruency test, the phantom could be used to detect 0.3 mm deviations of the CBCT isocenter from the radiation isocenter. Using the Mosfet in phantom as target, the difference between TPS calculations and measurements was within 5%. Image-quality parameters could also be assessed in terms of geometric accuracy, CT number accuracy, linearity, noise and image uniformity, etc. Conclusion: The developed phantom can be employed as a simple tool for comprehensive performance evaluation of the SARRP. The study provides a reference for development of a comprehensive quality assurance program for the SARRP, with proposed tolerances and frequency of required tests.« less

SU-F-T-580: New Tumor Modeling Using 3D Gel Dosimeter for Brain Stereoctactic Radiotherpy (SRT)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chang, K; Kim, M; Kwak, J

Purpose: The purpose of this study is to develop new tumor model using 3D printing with 3D dosimeter for brain stereoctactic radiotherpy (SRT). Methods: BANG{sup 3} polymer gel was prepared and the gel-filled glass vials were irradiated with a 6 MV photon beam to acquire the calibration curve that present the change of R2 (1/T{sub 2}) value with dose. Graded doses from 0 to 12 Gy with an interval of 2 Gy were delivered. A kit for calibration of gel dosimeter and an 2 tumor model phantoms with a spherical shape were produced using a 3D printer with a polylacticmore » acid after its 3D images were created using Autodesk software. 3D printed tumor phantoms and EBT3 films were irradiated to compare with treatment plan. After irradiation, vials for calibration and tumor model phantoms were scanned at 9.4T MRI. The spin-spin relaxation times (T{sub 2}) according to the each dose were calculated to evaluate the dose response. Acquired images were analyzed using an ImageJ. Scanned MRI images of tumor models were transferred treatment planning system and these were registered to the CT images. In all treatment plans, two arc plans (CW and CCW) were designed to deliver 50 Gy for 10 fractions. For first PTV, treatment plan was accurately designed that 95% of dose to cover 100% of PTV. But 2nd PTV was not intentionally cover 100% of PTV to evaluate the intensity of delivered tumor phantom with polymer gel. We compared the 3D dose distributions obtained from measurements with the 3D printed phantom and calculated with the TPS. Results: 3D printed phantom with a polymer gel was successfully produced. The dose distributions showed qualitatively good agreement among gel, film, and RTP data. Conclusion: A hybrid phantom represents a useful to validate the 3D dose distributions for patient-specific QA.« less

Design of a liquid membrane target for high repetition rate neutron generation

NASA Astrophysics Data System (ADS)

Poole, Patrick; Andereck, C. David; Storm, Mike; Schumacher, Douglass

2013-10-01

Ultra-bright, pulsed, spatially-small sources of energetic neutrons have applications in radiography and non-destructive remote sensing. Neutrons can be generated by a process wherein ions accelerated from a laser-irradiated primary target subsequently bombard a converter material, causing neutron-producing nuclear reactions, such as 7Li(d,n)8Be. Deuterons from this process are suppressed by contamination that builds up on the rear of the solid primary target. To eliminate this issue we propose a self-replenishing liquid membrane target consisting of heavy water and deuterated surfactant, formed in-vacuum within a moveable wire frame. In addition to removing issues associated with solid target positioning and collateral damage, this apparatus provides flow rate and target thickness control, and allows for the high repetition rates required to generate desired neutron fluxes with a portable laser-based system. The apparatus design will be presented, as well as a novel interferometric method that measures the membrane thickness using tightly-focused light. This work was performed with support from DARPA.

Design and development of a non-rigid phantom for the quantitative evaluation of DIR-based mapping of simulated pulmonary ventilation.

PubMed

Miyakawa, Shin; Tachibana, Hidenobu; Moriya, Shunsuke; Kurosawa, Tomoyuki; Nishio, Teiji; Sato, Masanori

2018-05-28

The validation of deformable image registration (DIR)-based pulmonary ventilation mapping is time-consuming and prone to inaccuracies and is also affected by deformation parameters. In this study, we developed a non-rigid phantom as a quality assurance (QA) tool that simulates ventilation to evaluate DIR-based images quantitatively. The phantom consists of an acrylic cylinder filled with polyurethane foam designed to simulate pulmonic alveoli. A polyurethane membrane is attached to the inferior end of the phantom to simulate the diaphragm. In addition, tracheobronchial-tree-shaped polyurethane tubes are inserted through the foam and converge outside the phantom to simulate the trachea. Solid polyurethane is also used to model arteries, which closely follow the model airways. Two three-dimensional CT scans were performed during exhalation and inhalation phases using xenon (Xe) gas as the inhaled contrast agent. The exhalation 3D-CT image is deformed to an inhalation 3D-CT image using our in-house program based on the NiftyReg open-source package. The target registration error (TRE) between the two images was calculated for 16 landmarks located in the simulated lung volume. The DIR-based ventilation image was generated using Jacobian determinant (JD) metrics. Subsequently, differences in the Hounsfield unit (HU) values between the two images were measured. The correlation coefficient between the JD and HU differences was calculated. In addition, three 4D-CT scans are performed to evaluate the reproducibility of the phantom motion and Xe gas distribution. The phantom exhibited a variety of displacements for each landmark (range: 1-20 mm). The reproducibility analysis indicated that the location differences were < 1 mm for all landmarks, and the HU variation in the Xe gas distribution was close to zero. The mean TRE in the evaluation of spatial accuracy according to the DIR software was 1.47 ± 0.71 mm (maximum: 2.6 mm). The relationship between the JD and HU differences had a large correlation (R = -0.71) for the DIR software. The phantom implemented new features, namely, deformation and simulated ventilation. To assess the accuracy of the DIR-based mapping of the simulated pulmonary ventilation, the phantom allows for simulation of Xe gas wash-in and wash-out. The phantom may be an effective QA tool, because the DIR algorithm can be quickly changed and its accuracy evaluated with a high degree of precision. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Integro-differential equation analysis and radioisotope imaging systems. Research proposal. [Testing of radioisotope imaging system in phantoms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hart, H.

1976-03-09

Design modifications of a five-probe focusing collimator coincidence radioisotope scanning system are described. Clinical applications of the system were tested in phantoms using radioisotopes with short biological half-lives, including /sup 75/Se, /sup 192/Ir, /sup 43/K, /sup 130/I, and /sup 82/Br. Data processing methods are also described. (CH)

A deformable head and neck phantom with in-vivo dosimetry for adaptive radiotherapy quality assurance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Graves, Yan Jiang; Smith, Arthur-Allen; Mcilvena, David

Purpose: Patients’ interfractional anatomic changes can compromise the initial treatment plan quality. To overcome this issue, adaptive radiotherapy (ART) has been introduced. Deformable image registration (DIR) is an important tool for ART and several deformable phantoms have been built to evaluate the algorithms’ accuracy. However, there is a lack of deformable phantoms that can also provide dosimetric information to verify the accuracy of the whole ART process. The goal of this work is to design and construct a deformable head and neck (HN) ART quality assurance (QA) phantom with in vivo dosimetry. Methods: An axial slice of a HN patientmore » is taken as a model for the phantom construction. Six anatomic materials are considered, with HU numbers similar to a real patient. A filled balloon inside the phantom tissue is inserted to simulate tumor. Deflation of the balloon simulates tumor shrinkage. Nonradiopaque surface markers, which do not influence DIR algorithms, provide the deformation ground truth. Fixed and movable holders are built in the phantom to hold a diode for dosimetric measurements. Results: The measured deformations at the surface marker positions can be compared with deformations calculated by a DIR algorithm to evaluate its accuracy. In this study, the authors selected a Demons algorithm as a DIR algorithm example for demonstration purposes. The average error magnitude is 2.1 mm. The point dose measurements from the in vivo diode dosimeters show a good agreement with the calculated doses from the treatment planning system with a maximum difference of 3.1% of prescription dose, when the treatment plans are delivered to the phantom with original or deformed geometry. Conclusions: In this study, the authors have presented the functionality of this deformable HN phantom for testing the accuracy of DIR algorithms and verifying the ART dosimetric accuracy. The authors’ experiments demonstrate the feasibility of this phantom serving as an end-to-end ART QA phantom.« less

Finite-element modeling of compression and gravity on a population of breast phantoms for multimodality imaging simulation.

PubMed

Sturgeon, Gregory M; Kiarashi, Nooshin; Lo, Joseph Y; Samei, E; Segars, W P

2016-05-01

The authors are developing a series of computational breast phantoms based on breast CT data for imaging research. In this work, the authors develop a program that will allow a user to alter the phantoms to simulate the effect of gravity and compression of the breast (craniocaudal or mediolateral oblique) making the phantoms applicable to multimodality imaging. This application utilizes a template finite-element (FE) breast model that can be applied to their presegmented voxelized breast phantoms. The FE model is automatically fit to the geometry of a given breast phantom, and the material properties of each element are set based on the segmented voxels contained within the element. The loading and boundary conditions, which include gravity, are then assigned based on a user-defined position and compression. The effect of applying these loads to the breast is computed using a multistage contact analysis in FEBio, a freely available and well-validated FE software package specifically designed for biomedical applications. The resulting deformation of the breast is then applied to a boundary mesh representation of the phantom that can be used for simulating medical images. An efficient script performs the above actions seamlessly. The user only needs to specify which voxelized breast phantom to use, the compressed thickness, and orientation of the breast. The authors utilized their FE application to simulate compressed states of the breast indicative of mammography and tomosynthesis. Gravity and compression were simulated on example phantoms and used to generate mammograms in the craniocaudal or mediolateral oblique views. The simulated mammograms show a high degree of realism illustrating the utility of the FE method in simulating imaging data of repositioned and compressed breasts. The breast phantoms and the compression software can become a useful resource to the breast imaging research community. These phantoms can then be used to evaluate and compare imaging modalities that involve different positioning and compression of the breast.

Dosimetric evaluation of Plastic Water Diagnostic-Therapy.

PubMed

Ramaseshan, Ramani; Kohli, Kirpal; Cao, Fred; Heaton, Robert K

2008-04-29

High-precision radiotherapy planning and quality assurance require accurate dosimetric and geometric phantom measurements. Phantom design requires materials with mechanical strength and resilience, and dosimetric properties close to those of water over diagnostic and therapeutic ranges. Plastic Water Diagnostic Therapy (PWDT: CIRS, Norfolk, VA) is a phantom material designed for water equivalence in photon beams from 0.04 MeV to 100 MeV; the material has also good mechanical properties. The present article reports the results of computed tomography (CT) imaging and dosimetric studies of PWDT to evaluate the suitability of the material in CT and therapy energy ranges. We characterized the water equivalence of PWDT in a series of experiments in which the basic dosimetric properties of the material were determined for photon energies of 80 kVp, 100 kVp, 250 kVp, 4 MV, 6 MV, 10 MV, and 18 MV. Measured properties included the buildup and percentage depth dose curves for several field sizes, and relative dose factors as a function of field size. In addition, the PWDT phantom underwent CT imaging at beam qualities ranging from 80 kVp to 140 kVp to determine the water equivalence of the phantom in the diagnostic energy range. The dosimetric quantities measured with PWDT agreed within 1.5% of those determined in water and Solid Water (Gammex rmi, Middleton, WI). Computed tomography imaging of the phantom was found to generate Hounsfield numbers within 0.8% of those generated using water. The results suggest that PWDT material is suitable both for regular radiotherapy quality assurance measurements and for intensity-modulated radiation therapy (IMRT) verification work. Sample IMRT verification results are presented.

Molecular imaging using light-absorbing imaging agents and a clinical optical breast imaging system--a phantom study.

PubMed

van de Ven, Stephanie M W Y; Mincu, Niculae; Brunette, Jean; Ma, Guobin; Khayat, Mario; Ikeda, Debra M; Gambhir, Sanjiv S

2011-04-01

The aim of the study was to determine the feasibility of using a clinical optical breast scanner with molecular imaging strategies based on modulating light transmission. Different concentrations of single-walled carbon nanotubes (SWNT; 0.8-20.0 nM) and black hole quencher-3 (BHQ-3; 2.0-32.0 µM) were studied in specifically designed phantoms (200-1,570 mm(3)) with a clinical optical breast scanner using four wavelengths. Each phantom was placed in the scanner tank filled with optical matching medium. Background scans were compared to absorption scans, and reproducibility was assessed. All SWNT phantoms were detected at four wavelengths, with best results at 684 nm. Higher concentrations (≥8.0 µM) were needed for BHQ-3 detection, with the largest contrast at 684 nm. The optical absorption signal was dependent on phantom size and concentration. Reproducibility was excellent (intraclass correlation 0.93-0.98). Nanomolar concentrations of SWNT and micromolar concentrations of BHQ-3 in phantoms were reproducibly detected, showing the potential of light absorbers, with appropriate targeting ligands, as molecular imaging agents for clinical optical breast imaging.

Multimodal 3D cancer-mimicking optical phantom

PubMed Central

Smith, Gennifer T.; Lurie, Kristen L.; Zlatev, Dimitar V.; Liao, Joseph C.; Ellerbee Bowden, Audrey K.

2016-01-01

Three-dimensional (3D) organ-mimicking phantoms provide realistic imaging environments for testing various aspects of optical systems, including for evaluating new probe designs, characterizing the diagnostic potential of new technologies, and assessing novel image processing algorithms prior to validation in real tissue. We introduce and characterize the use of a new material, Dragon Skin (Smooth-On Inc.), and fabrication technique, air-brushing, for fabrication of a 3D phantom that mimics the appearance of a real organ under multiple imaging modalities. We demonstrate the utility of the material and technique by fabricating the first 3D, hollow bladder phantom with realistic normal and multi-stage pathology features suitable for endoscopic detection using the gold standard imaging technique, white light cystoscopy (WLC), as well as the complementary imaging modalities of optical coherence tomography and blue light cystoscopy, which are aimed at improving the sensitivity and specificity of WLC to bladder cancer detection. The flexibility of the material and technique used for phantom construction allowed for the representation of a wide range of diseased tissue states, ranging from inflammation (benign) to high-grade cancerous lesions. Such phantoms can serve as important tools for trainee education and evaluation of new endoscopic instrumentation. PMID:26977369

A review of consensus test methods for established medical imaging modalities and their implications for optical coherence tomography

NASA Astrophysics Data System (ADS)

Pfefer, Joshua; Agrawal, Anant

2012-03-01

In recent years there has been increasing interest in development of consensus, tissue-phantom-based approaches for assessment of biophotonic imaging systems, with the primary goal of facilitating clinical translation of novel optical technologies. Well-characterized test methods based on tissue phantoms can provide useful tools for performance assessment, thus enabling standardization and device inter-comparison during preclinical development as well as quality assurance and re-calibration in the clinical setting. In this review, we study the role of phantom-based test methods as described in consensus documents such as international standards for established imaging modalities including X-ray CT, MRI and ultrasound. Specifically, we focus on three image quality characteristics - spatial resolution, spatial measurement accuracy and image uniformity - and summarize the terminology, metrics, phantom design/construction approaches and measurement/analysis procedures used to assess these characteristics. Phantom approaches described are those in routine clinical use and tend to have simplified morphology and biologically-relevant physical parameters. Finally, we discuss the potential for applying knowledge gained from existing consensus documents in the development of standardized, phantom-based test methods for optical coherence tomography.

WE-DE-207B-11: Implementation of Size-Specific 3D Beam Modulation Filters On a Dedicated Breast CT Platform Using Breast Immobilization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hernandez, A; Boone, J

Purpose: To implement a 3D beam modulation filter (3D-BMF) in dedicated breast CT (bCT) and develop a method for conforming the patient’s breast to a pre-defined shape, optimizing the effects of the filter. This work expands on previous work reporting the methodology for designing a 3D-BMF that can spare unnecessary dose and improve signal equalization at the detector by preferentially filtering the beam in the thinner anterior and peripheral breast regions. Methods: Effective diameter profiles were measured for 219 segmented bCT images, grouped into volume quintiles, and averaged within each group to represent the range of breast sizes found clinically.more » These profiles were then used to generate five size-specific computational phantoms and fabricate five size-specific UHMW phantoms. Each computational phantom was utilized for designing a size-specific 3D-BMF using previously reported methods. Glandular dose values and projection images were simulated in MCNP6 with and without the 3DBMF using the system specifications of our prototype bCT scanner “Doheny”. Lastly, thermoplastic was molded around each of the five phantom sizes and used to produce a series of breast immobilizers for use in conforming the patient’s breast during bCT acquisition. Results: After incorporating the 3D-BMF, MC simulations estimated an 80% average reduction in the detector dynamic range requirements across all phantom sizes. The glandular dose was reduced on average 57% after normalizing by the number of quanta reaching the detector under the thickest region of the breast. Conclusion: A series of bCT-derived breast phantoms were used to design size-specific 3D-BMFs and breast immobilizers that can be used on the bCT platform to conform the patient’s breast and therefore optimally exploit the benefits of the 3D-BMF. Current efforts are focused on fabricating several prototype 3D-BMFs and performing phantom scans on Doheny for MC simulation validation and image quality analysis. Research reported in this paper was supported in part by the National Cancer Institute of the National Institutes of Health under award R01CA181081. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institue of Health.« less

A 20-Channel Receive-Only Mouse Array Coil for a 3T Clinical MRI System

PubMed Central

Keil, Boris; Wiggins, Graham C.; Triantafyllou, Christina; Wald, Lawrence L.; Meise, Florian M.; Schreiber, Laura M.; Klose, Klaus J.; Heverhagen, Johannes T.

2010-01-01

A 20-channel phased-array coil for Magnetic Resonance Imaging (MRI) of mice has been designed, constructed and validated with bench measurements and high resolution accelerated imaging. The technical challenges of designing a small, high density array have been overcome using individual small-diameter coil elements arranged on a cylinder in a hexagonal overlapping design with adjacent low impedance preamplifiers to further decouple the array elements. Signal-to-noise ratio (SNR) and noise amplification in accelerated imaging were simulated and quantitatively evaluated in phantoms and in vivo mouse images. Comparison between the 20-channel mouse array and a length-matched quadrature driven small animal birdcage coil showed an SNR increase at the periphery and in the center of the phantom of 3-fold and 1.3-fold, respectively. Comparison to a shorter but SNR-optimized birdcage coil (aspect ratio 1:1 and only half mouse coverage) showed an SNR gain of 2-fold at the edge of the phantom and similar SNR in the center. G-factor measurements indicate that the coil is well suited to acquire highly accelerated images. PMID:21433066

[Design of magneto-acoustic-electrical detection system and verification of its linear sweep theory].

PubMed

Dai, Ming; Chen, Siping; Li, Fangfang; Chen, Mian; Lin, Haoming; Chen, Xin

2018-02-01

Clinical studies had demonstrated that early diagnosis of lesion could significantly reduce the risk of cancer. Magneto-acoustic-electrical tomography (MAET) is expected to become a new detection method due to its advantages of high resolution and high contrast. Based on thinking of modular design, a low-cost, digital magneto-acoustic conductivity detection system was designed and implemented in this study. The theory of MAET using chirp continuous wave excitation was introduced. The results of homogeneous phantom experiment with 0.5% NaCl clearly showed that the conductivity curve of homogeneous phantom was highly consistent with the actual physical size, which indicated that the chirp excitation theory in our proposed system was correct and feasible. Besides, the resolution obtained by 1 000 μs sweep time was better than that obtained by 500 μs and 1 500 μs, which means that sweep time is an important factor affecting the detection resolution of the conductivity. The same result was obtained in the experiments carried out on homogeneous phantoms with different concentrations of NaCl, which demonstrated the repeatability of our proposed MAET system.

Multi-orifice deposition nozzle for additive manufacturing

DOEpatents

Lind, Randall F.; Post, Brian K.; Cini, Colin L.

2017-11-21

An additive manufacturing extrusion head includes a nozzle for accepting and depositing a heated material onto a work surface and/or part. The nozzle includes a valve body and an internal poppet body moveable between positions to permit deposition of at least two bead sizes of heated material onto a work surface and/or part.

19. EMPTY SEDIMENTATION TANKS. TOP LAYER OF WATER FLOWS OVER ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

19. EMPTY SEDIMENTATION TANKS. TOP LAYER OF WATER FLOWS OVER TRIANGULATED CHANNELS AND OUT THE RAISED DUCTS TO FILTRATION PLANT. MOVEABLE BOARDS ON BOTTOM ASSIST IN REMOVING SLUDGE. VIEW LOOKING NORTHEAST. FILTER CONTROL BUILDING AT REAR. - F. E. Weymouth Filtration Plant, 700 North Moreno Avenue, La Verne, Los Angeles County, CA

Ground Vehicle Power and Mobility Overview - Germany Visit

DTIC Science & Technology

2011-11-10

the current and future force Survivability Robotics – Intelligent Systems Vehicle Electronics & Architecture Fuel, Water, Bridging ...Test Cell • Engine Generator Test Lab • Full Vehicle Environmental Test Cell • Hybrid Electric Reconfigurable Moveable Integration Testbed (HERMIT...Converter Conducted competitive runoff evaluations on Bridging Boat engine candidates Completed independent durability assessment of OEM

Information Technology: Better Informed Decision Making Needed on Navy’s Next Generation Enterprise Network Acquisition

DTIC Science & Technology

2011-03-01

million. To bridge the time frame between the end of the NMCI contract and the full transition to NGEN, DON awarded a $3.7 billion continuity of...leasehold improvements; and moveable infrastructure associated with local network operations. End-User Hardware December 2011 Provide end-user

78 FR 44881 - Drawbridge Operation Regulation; York River, Between Yorktown and Gloucester Point, VA

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-25

... deviation from the operating schedule that governs the operation of the Coleman Memorial Bridge (US 17/George P. Coleman Memorial Swing Bridge) across the York River, mile 7.0, between Gloucester Point and Yorktown, VA. This deviation is necessary to facilitate maintenance work on the moveable spans on the...

Planning Guide for Fish Passage at Pittsburgh District Dams

DTIC Science & Technology

2013-08-01

attracted to a downstream flow at the entrance gate of the lift. 2) Immigrants pass around a moveable crowder that, when engaged, forces fish into the...might influence fish passage over a large number of sites. REFERENCES Bailey, M. M., J. J. Isely, and W. C. Bridges , Jr. 2004. Movement and

49 CFR 571.118 - Standard No. 118; Power-operated window, partition, and roof panel systems.

Code of Federal Regulations, 2011 CFR

2011-10-01

...-operated window, partition, and roof panel systems. S1. Purpose and scope. This standard specifies requirements for power operated window, partition, and roof panel systems to minimize the likelihood of death... Figure 2. Power operated roof panel systems mean moveable panels in the vehicle roof which close by...

49 CFR 571.118 - Standard No. 118; Power-operated window, partition, and roof panel systems.

Code of Federal Regulations, 2014 CFR

2014-10-01

...-operated window, partition, and roof panel systems. S1. Purpose and scope. This standard specifies requirements for power operated window, partition, and roof panel systems to minimize the likelihood of death... Figure 2. Power operated roof panel systems mean moveable panels in the vehicle roof which close by...

49 CFR 571.118 - Standard No. 118; Power-operated window, partition, and roof panel systems.

Code of Federal Regulations, 2012 CFR

2012-10-01

...-operated window, partition, and roof panel systems. S1. Purpose and scope. This standard specifies requirements for power operated window, partition, and roof panel systems to minimize the likelihood of death... Figure 2. Power operated roof panel systems mean moveable panels in the vehicle roof which close by...

49 CFR 571.118 - Standard No. 118; Power-operated window, partition, and roof panel systems.

Code of Federal Regulations, 2013 CFR

2013-10-01

...-operated window, partition, and roof panel systems. S1. Purpose and scope. This standard specifies requirements for power operated window, partition, and roof panel systems to minimize the likelihood of death... Figure 2. Power operated roof panel systems mean moveable panels in the vehicle roof which close by...

49 CFR 571.118 - Standard No. 118; Power-operated window, partition, and roof panel systems.

Code of Federal Regulations, 2010 CFR

2010-10-01

...-operated window, partition, and roof panel systems. S1. Purpose and scope. This standard specifies requirements for power operated window, partition, and roof panel systems to minimize the likelihood of death... Figure 2. Power operated roof panel systems mean moveable panels in the vehicle roof which close by...

A biological phantom for evaluation of CT image reconstruction algorithms

NASA Astrophysics Data System (ADS)

Cammin, J.; Fung, G. S. K.; Fishman, E. K.; Siewerdsen, J. H.; Stayman, J. W.; Taguchi, K.

2014-03-01

In recent years, iterative algorithms have become popular in diagnostic CT imaging to reduce noise or radiation dose to the patient. The non-linear nature of these algorithms leads to non-linearities in the imaging chain. However, the methods to assess the performance of CT imaging systems were developed assuming the linear process of filtered backprojection (FBP). Those methods may not be suitable any longer when applied to non-linear systems. In order to evaluate the imaging performance, a phantom is typically scanned and the image quality is measured using various indices. For reasons of practicality, cost, and durability, those phantoms often consist of simple water containers with uniform cylinder inserts. However, these phantoms do not represent the rich structure and patterns of real tissue accurately. As a result, the measured image quality or detectability performance for lesions may not reflect the performance on clinical images. The discrepancy between estimated and real performance may be even larger for iterative methods which sometimes produce "plastic-like", patchy images with homogeneous patterns. Consequently, more realistic phantoms should be used to assess the performance of iterative algorithms. We designed and constructed a biological phantom consisting of porcine organs and tissue that models a human abdomen, including liver lesions. We scanned the phantom on a clinical CT scanner and compared basic image quality indices between filtered backprojection and an iterative reconstruction algorithm.

Assessment of Geometrical Accuracy of Multimodal Images Used for Treatment Planning in Stereotactic Radiotherapy and Radiosurgery: CT, MRI and PET

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garcia-Garduno, O. A.; Larraga-Gutierrez, J. M.; Celis, M. A.

2006-09-08

An acrylic phantom was designed and constructed to assess the geometrical accuracy of CT, MRI and PET images for stereotactic radiotherapy (SRT) and radiosurgery (SRS) applications. The phantom was suited for each image modality with a specific tracer and compared with CT images to measure the radial deviation between the reference marks in the phantom. It was found that for MRI the maximum mean deviation is 1.9 {+-} 0.2 mm compared to 2.4 {+-} 0.3 mm reported for PET. These results will be used for margin outlining in SRS and SRT treatment planning.

Fan-beam scanning laser optical computed tomography for large volume dosimetry

NASA Astrophysics Data System (ADS)

Dekker, K. H.; Battista, J. J.; Jordan, K. J.

2017-05-01

A prototype scanning-laser fan beam optical CT scanner is reported which is capable of high resolution, large volume dosimetry with reasonable scan time. An acylindrical, asymmetric aquarium design is presented which serves to 1) generate parallel-beam scan geometry, 2) focus light towards a small acceptance angle detector, and 3) avoid interference fringe-related artifacts. Preliminary experiments with uniform solution phantoms (11 and 15 cm diameter) and finger phantoms (13.5 mm diameter FEP tubing) demonstrate that the design allows accurate optical CT imaging, with optical CT measurements agreeing within 3% of independent Beer-Lambert law calculations.

Automated model-based quantitative analysis of phantoms with spherical inserts in FDG PET scans.

PubMed

Ulrich, Ethan J; Sunderland, John J; Smith, Brian J; Mohiuddin, Imran; Parkhurst, Jessica; Plichta, Kristin A; Buatti, John M; Beichel, Reinhard R

2018-01-01

Quality control plays an increasingly important role in quantitative PET imaging and is typically performed using phantoms. The purpose of this work was to develop and validate a fully automated analysis method for two common PET/CT quality assurance phantoms: the NEMA NU-2 IQ and SNMMI/CTN oncology phantom. The algorithm was designed to only utilize the PET scan to enable the analysis of phantoms with thin-walled inserts. We introduce a model-based method for automated analysis of phantoms with spherical inserts. Models are first constructed for each type of phantom to be analyzed. A robust insert detection algorithm uses the model to locate all inserts inside the phantom. First, candidates for inserts are detected using a scale-space detection approach. Second, candidates are given an initial label using a score-based optimization algorithm. Third, a robust model fitting step aligns the phantom model to the initial labeling and fixes incorrect labels. Finally, the detected insert locations are refined and measurements are taken for each insert and several background regions. In addition, an approach for automated selection of NEMA and CTN phantom models is presented. The method was evaluated on a diverse set of 15 NEMA and 20 CTN phantom PET/CT scans. NEMA phantoms were filled with radioactive tracer solution at 9.7:1 activity ratio over background, and CTN phantoms were filled with 4:1 and 2:1 activity ratio over background. For quantitative evaluation, an independent reference standard was generated by two experts using PET/CT scans of the phantoms. In addition, the automated approach was compared against manual analysis, which represents the current clinical standard approach, of the PET phantom scans by four experts. The automated analysis method successfully detected and measured all inserts in all test phantom scans. It is a deterministic algorithm (zero variability), and the insert detection RMS error (i.e., bias) was 0.97, 1.12, and 1.48 mm for phantom activity ratios 9.7:1, 4:1, and 2:1, respectively. For all phantoms and at all contrast ratios, the average RMS error was found to be significantly lower for the proposed automated method compared to the manual analysis of the phantom scans. The uptake measurements produced by the automated method showed high correlation with the independent reference standard (R 2 ≥ 0.9987). In addition, the average computing time for the automated method was 30.6 s and was found to be significantly lower (P ≪ 0.001) compared to manual analysis (mean: 247.8 s). The proposed automated approach was found to have less error when measured against the independent reference than the manual approach. It can be easily adapted to other phantoms with spherical inserts. In addition, it eliminates inter- and intraoperator variability in PET phantom analysis and is significantly more time efficient, and therefore, represents a promising approach to facilitate and simplify PET standardization and harmonization efforts. © 2017 American Association of Physicists in Medicine.

Variable stator radial turbine

NASA Technical Reports Server (NTRS)

Rogo, C.; Hajek, T.; Chen, A. G.

1984-01-01

A radial turbine stage with a variable area nozzle was investigated. A high work capacity turbine design with a known high performance base was modified to accept a fixed vane stagger angle moveable sidewall nozzle. The nozzle area was varied by moving the forward and rearward sidewalls. Diffusing and accelerating rotor inlet ramps were evaluated in combinations with hub and shroud rotor exit rings. Performance of contoured sidewalls and the location of the sidewall split line with respect to the rotor inlet was compared to the baseline. Performance and rotor exit survey data are presented for 31 different geometries. Detail survey data at the nozzle exit are given in contour plot format for five configurations. A data base is provided for a variable geometry concept that is a viable alternative to the more common pivoted vane variable geometry radial turbine.

Variable area radial turbine fabrication and test program

NASA Technical Reports Server (NTRS)

Rogo, C.

1986-01-01

A variable area radial turbine with a moveable nozzle sidewall was experimentally evaluated. The turbine was designed for an advanced variable capacity gas turbine rotorcraft engine. The turbine has a mass flow rate of 2.27 kg/sec (5.0 lbs/sec), and a rotor inlet temperature of 1477K (2200 F). Testing was conducted at a reduced inlet temperature, but the aerodynamic parameters and Reynolds numbers were duplicated. Overall performance was obtained for a range of nozzle areas from 50% to 100% of the maximum area. The test program determined the effect on performance of: (1) Moving the hub or shroud sidewall; (2) Sidewall-vane clearance leakage; (3) Vaneless space geometry change; and (4) Nozzle cooling flows. Data were obtained for a range of pressure ratios and speeds and are presented in a number of performance maps.

Three-dimensional printed ultrasound and photoacoustic training phantoms for vasculature access (Conference Presentation)

NASA Astrophysics Data System (ADS)

Nikitichev, Daniil I.; Xia, Wenfeng; West, Simeon J.; Desjardins, Adrien E.; Ourselin, Sebastien; Vercauteren, Tom

2017-03-01

Ultrasound (US) imaging is widely used to guide vascular access procedures such as arterial and venous cannulation. As needle visualisation with US imaging can be very challenging, it is easy to misplace the needle in the patient and it can be life threating. Photoacoustic (PA) imaging is well suited to image medical needles and catheters that are commonly used for vascular access. To improve the success rate, a certain level of proficiency is required that can be gained through extensive practice on phantoms. Unfortunately, commercial training phantoms are expensive and custom-made phantoms usually do not replicate the anatomy very well. Thus, there is a great demand for more realistic and affordable ultrasound and photoacoustic imaging phantoms for vasculature access procedures training. Three-dimensional (3D) printing can help create models that replicate complex anatomical geometries. However, the available 3D printed materials do not possess realistic tissue properties. Alternatively, tissue-mimicking materials can be employed using casting and 3D printed moulds but this approach is limited to the creation of realistic outer shapes with no replication of complex internal structures. In this study, we developed a realistic vasculature access phantom using a combination of mineral oil based materials as background tissue and a non-toxic, water dissolvable filament material to create complex vascular structure using 3D printing. US and PA images of the phantoms comprising the complex vasculature network were acquired. The results show that 3D printing can facilitate the fabrication of anatomically realistic training phantoms, with designs that can be customized and shared electronically.

SU-E-T-124: Anthropomorphic Phantoms for Confirmation of Linear Accelerator Based Small Animal Irradiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Perks, J; Benedict, S; Lucero, S

Purpose: To document the support of radiobiological small animal research by a modern radiation oncology facility. This study confirms that a standard, human use linear accelerator can cover the range of experiments called for by researchers performing animal irradiation. A number of representative, anthropomorphic murine phantoms were made. The phantoms confirmed the small field photon and electron beams dosimetry validated the use of the linear accelerator for rodents. Methods: Laser scanning a model, CAD design and 3D printing produced the phantoms. The phantoms were weighed and CT scanned to judge their compatibility to real animals. Phantoms were produced to specificallymore » mimic lung, gut, brain, and othotopic lesion irradiations. Each phantom was irradiated with the same protocol as prescribed to the live animals. Delivered dose was measured with small field ion chambers, MOS/FETs or TLDs. Results: The density of the phantom material compared to density range across the real mice showed that the printed material would yield sufficiently accurate measurements when irradiated. The whole body, lung and gut irradiations were measured within 2% of prescribed doses with A1SL ion chamber. MOSFET measurements of electron irradiations for the orthotopic lesions allowed refinement of the measured small field output factor to better than 2% and validated the immunology experiment of irradiating one lesion and sparing another. Conclusion: Linacs are still useful tools in small animal bio-radiation research. This work demonstrated a strong role for the clinical accelerator in small animal research, facilitating standard whole body dosing as well as conformal treatments down to 1cm field. The accuracy of measured dose, was always within 5%. The electron irradiations of the phantom brain and flank tumors needed adjustment; the anthropomorphic phantoms allowed refinement of the initial output factor measurements for these fields which were made in a large block of solid water.« less

Characterization of a high-energy in-line phase contrast tomosynthesis prototype.

PubMed

Wu, Di; Yan, Aimin; Li, Yuhua; Wong, Molly D; Zheng, Bin; Wu, Xizeng; Liu, Hong

2015-05-01

In this research, a high-energy in-line phase contrast tomosynthesis prototype was developed and characterized through quantitative investigations and phantom studies. The prototype system consists of an x-ray source, a motorized rotation stage, and a CMOS detector with a pixel pitch of 0.05 mm. The x-ray source was operated at 120 kVp for this study, and the objects were mounted on the rotation stage 76.2 cm (R1) from the source and 114.3 cm (R2) from the detector. The large air gap between the object and detector guarantees sufficient phase-shift effects. The quantitative evaluation of this prototype included modulation transfer function and noise power spectrum measurements conducted under both projection mode and tomosynthesis mode. Phantom studies were performed including three custom designed phantoms with complex structures: a five-layer bubble wrap phantom, a fishbone phantom, and a chicken breast phantom with embedded fibrils and mass structures extracted from an ACR phantom. In-plane images of the phantoms were acquired to investigate their image qualities through observation, intensity profile plots, edge enhancement evaluations, and/or contrast-to-noise ratio calculations. In addition, the robust phase-attenuation duality (PAD)-based phase retrieval method was applied to tomosynthesis for the first time in this research. It was utilized as a preprocessing method to fully exhibit phase contrast on the angular projection before reconstruction. The resolution and noise characteristics of this high-energy in-line phase contrast tomosynthesis prototype were successfully investigated and demonstrated. The phantom studies demonstrated that this imaging prototype can successfully remove the structure overlapping in phantom projections, obtain delineate interfaces, and achieve better contrast-to-noise ratio after applying phase retrieval to the angular projections. This research successfully demonstrated a high-energy in-line phase contrast tomosynthesis prototype. In addition, the PAD-based method of phase retrieval was combined with tomosynthesis imaging for the first time, which demonstrated its capability in significantly improving the contrast-to-noise ratios in the images.

TU-F-CAMPUS-I-04: A Novel Phantom to Evaluate Longitudinal and Angular Automatic Tube Current Modulation (ATCM) in CT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Merzan, D; Bujila, R; Nowik, P

Purpose: To manufacture a phantom specifically designed for the purpose of evaluating the performance of the longitudinal and angular automatic tube current modulation (ATCM) on modern CT scanners. Methods: In order to evaluate angular ATCM, the phantom has an elliptical cross section (aspect ratio 3:2). To evaluate longitudinal ATCM, the phantom consists of 3 sections, with different major axes (25 cm, 30 cm and 35 cm). Each section is 15 cm long in the longitudinal direction. Between each section is a smooth transition. The phantom was milled from a solid block of PMMA. ATCM performance is evaluated by 1) analyzingmore » the applied tube current for each slice of the phantom and 2) analyzing the distribution of image noise (σ) along the scan direction at different positions in the phantom. A demonstration of the ATCM performance evaluation is given by investigating the effects of miscentering during a CT scan. Results: The developed phantom has proven useful for evaluating both the longitudinal and angular ATCM on modern CT scanners (spiral collimations ≥ 4 cm). Further benefits are the smooth transitions between the sections that prevent abnormal responses in the ATCM and the invariant sections that provide a means for investigating the stability of image noise. The homogeneity of the phantom makes image noise at different positions along the scan direction easy to quantify, which is crucial to understand how well the applied ATCM can produce a desired image quality. Conclusion: It is important to understand how the ATCM functions on CT scanners as it can directly affect dose and image quality. The phantom that has been developed is a most valuable tool to understand how different variables during a scan can affect the outcome of the longitudinal and angular ATCM.« less

Cardiovascular Computed Tomography Phantom Fabrication and Characterization through the Tailored Properties of Polymeric Composites and Cellular Foams

NASA Astrophysics Data System (ADS)

Hoy, Carlton F. O.

The overall objective of this thesis was to control the fabrication technique and relevant material properties for phantom devices designated for computed tomography (CT) scanning. Fabrication techniques using polymeric composites and foams were detailed together with parametric studies outlining the fundamentals behind the changes in material properties which affect the characteristic CT number. The composites fabricated used polyvinylidene fluoride (PVDF), thermoplastic polyurethane (TPU) and polyethylene (PE) with hydroxylapatite (hA) as additive with different composites made by means of different weight percentages of additive. Polymeric foams were fabricated through a batch foaming technique with the heating time controlled to create different levels of foams. Finally, the effect of fabricated phantoms under varied scanning media was assessed to determine whether self-made phantoms can be scanned accurately under non-water or rigid environments allowing for the future development of complex shaped or fragile material types.

Induced sensorimotor brain plasticity controls pain in phantom limb patients

PubMed Central

Yanagisawa, Takufumi; Fukuma, Ryohei; Seymour, Ben; Hosomi, Koichi; Kishima, Haruhiko; Shimizu, Takeshi; Yokoi, Hiroshi; Hirata, Masayuki; Yoshimine, Toshiki; Kamitani, Yukiyasu; Saitoh, Youichi

2016-01-01

The cause of pain in a phantom limb after partial or complete deafferentation is an important problem. A popular but increasingly controversial theory is that it results from maladaptive reorganization of the sensorimotor cortex, suggesting that experimental induction of further reorganization should affect the pain, especially if it results in functional restoration. Here we use a brain–machine interface (BMI) based on real-time magnetoencephalography signals to reconstruct affected hand movements with a robotic hand. BMI training induces significant plasticity in the sensorimotor cortex, manifested as improved discriminability of movement information and enhanced prosthetic control. Contrary to our expectation that functional restoration would reduce pain, the BMI training with the phantom hand intensifies the pain. In contrast, BMI training designed to dissociate the prosthetic and phantom hands actually reduces pain. These results reveal a functional relevance between sensorimotor cortical plasticity and pain, and may provide a novel treatment with BMI neurofeedback. PMID:27807349

Design and Development of a Telerehabilitation Platform for Patients With Phantom Limb Pain: A User-Centered Approach.

PubMed

Rothgangel, Andreas; Braun, Susy; Smeets, Rob; Beurskens, Anna

2017-02-15

Phantom limb pain is a frequent and persistent problem following amputation. Achieving sustainable favorable effects on phantom limb pain requires therapeutic interventions such as mirror therapy that target maladaptive neuroplastic changes in the central nervous system. Unfortunately, patients' adherence to unsupervised exercises is generally poor and there is a need for effective strategies such as telerehabilitation to support long-term self-management of patients with phantom limb pain. The main aim of this study was to describe the user-centered approach that guided the design and development of a telerehabilitation platform for patients with phantom limb pain. We addressed 3 research questions: (1) Which requirements are defined by patients and therapists for the content and functions of a telerehabilitation platform and how can these requirements be prioritized to develop a first prototype of the platform? (2) How can the user interface of the telerehabilitation platform be designed so as to match the predefined critical user requirements and how can this interface be translated into a medium-fidelity prototype of the platform? (3) How do patients with phantom limb pain and their treating therapists judge the usability of the medium-fidelity prototype of the telerehabilitation platform in routine care and how can the platform be redesigned based on their feedback to achieve a high-fidelity prototype? The telerehabilitation platform was developed using an iterative user-centered design process. In the first phase, a questionnaire followed by a semistructured interview was used to identify the user requirements of both the patients and their physical and occupational therapists, which were then prioritized using a decision matrix. The second phase involved designing the interface of the telerehabilitation platform using design sketches, wireframes, and interface mock-ups to develop a low-fidelity prototype. Heuristic evaluation resulted in a medium-fidelity prototype whose usability was tested in routine care in the final phase, leading to the development of a high-fidelity prototype. A total of 7 categories of patient requirements were identified: monitoring, exercise programs, communication, settings, background information, log-in, and general requirements. One additional category emerged for therapists: patient management. Based on these requirements, patient and therapist interfaces for the telerehabilitation platform were developed and redesigned by the software development team in an iterative process, addressing the usability problems that were reported by the users during 4 weeks of field testing in routine care. Our findings underline the importance of involving the users and other stakeholders early and continuously in an iterative design process, as well as the need for clear criteria to identify critical user requirements. A decision matrix is presented that incorporates the views of various stakeholders in systematically rating and prioritizing user requirements. The findings and lessons learned might help health care providers, researchers, software designers, and other stakeholders in designing and evaluating new teletreatments, and hopefully increase the likelihood of user acceptance. ©Andreas Rothgangel, Susy Braun, Rob Smeets, Anna Beurskens. Originally published in JMIR Rehabilitation and Assistive Technology (http://rehab.jmir.org), 15.02.2017.

Integrated PET/MR breast cancer imaging: Attenuation correction and implementation of a 16-channel RF coil

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oehmigen, Mark, E-mail: mark.oehmigen@uni-due.de

Purpose: This study aims to develop, implement, and evaluate a 16-channel radiofrequency (RF) coil for integrated positron emission tomography/magnetic resonance (PET/MR) imaging of breast cancer. The RF coil is designed for optimized MR imaging performance and PET transparency and attenuation correction (AC) is applied for accurate PET quantification. Methods: A 16-channel breast array RF coil was designed for integrated PET/MR hybrid imaging of breast cancer lesions. The RF coil features a lightweight rigid design and is positioned with a spacer at a defined position on the patient table of an integrated PET/MR system. Attenuation correction is performed by generating andmore » applying a dedicated 3D CT-based template attenuation map. Reposition accuracy of the RF coil on the system patient table while using the positioning frame was tested in repeated measurements using MR-visible markers. The MR, PET, and PET/MR imaging performances were systematically evaluated using modular breast phantoms. Attenuation correction of the RF coil was evaluated with difference measurements of the active breast phantoms filled with radiotracer in the PET detector with and without the RF coil in place, serving as a standard of reference measurement. The overall PET/MR imaging performance and PET quantification accuracy of the new 16-channel RF coil and its AC were then evaluated in first clinical examinations on ten patients with local breast cancer. Results: The RF breast array coil provides excellent signal-to-noise ratio and signal homogeneity across the volume of the breast phantoms in MR imaging and visualizes small structures in the phantoms down to 0.4 mm in plane. Difference measurements with PET revealed a global loss and thus attenuation of counts by 13% (mean value across the whole phantom volume) when the RF coil is placed in the PET detector. Local attenuation ranging from 0% in the middle of the phantoms up to 24% was detected in the peripheral regions of the phantoms at positions closer to attenuating hardware structures of the RF coil. The position accuracy of the RF coil on the patient table when using the positioning frame was determined well below 1 mm for all three spatial dimensions. This ensures perfect position match between the RF coil and its three-dimensional attenuation template during the PET data reconstruction process. When applying the CT-based AC of the RF coil, the global attenuation bias was mostly compensated to ±0.5% across the entire breast imaging volume. The patient study revealed high quality MR, PET, and combined PET/MR imaging of breast cancer. Quantitative activity measurements in all 11 breast cancer lesions of the ten patients resulted in increased mean difference values of SUV{sub max} 11.8% (minimum 3.2%; maximum 23.2%) between nonAC images and images when AC of the RF breast coil was applied. This supports the quantitative results of the phantom study as well as successful attenuation correction of the RF coil. Conclusions: A 16-channel breast RF coil was designed for optimized MR imaging performance and PET transparency and was successfully integrated with its dedicated attenuation correction template into a whole-body PET/MR system. Systematic PET/MR imaging evaluation with phantoms and an initial study on patients with breast cancer provided excellent MR and PET image quality and accurate PET quantification.« less

Design and testing of a phantom and instrumented gynecological applicator based on GaN dosimeter for use in high dose rate brachytherapy quality assurance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guiral, P.; Ribouton, J.; Jalade, P.

Purpose: High dose rate brachytherapy (HDR-BT) is widely used to treat gynecologic, anal, prostate, head, neck, and breast cancers. These treatments are typically administered in large dose per fraction (>5 Gy) and with high-gradient-dose-distributions, with serious consequences in case of a treatment delivery error (e.g., on dwell position and dwell time). Thus, quality assurance (QA) or quality control (QC) should be systematically and independently implemented. This paper describes the design and testing of a phantom and an instrumented gynecological applicator for pretreatment QA and in vivo QC, respectively. Methods: The authors have designed a HDR-BT phantom equipped with four GaN-basedmore » dosimeters. The authors have also instrumented a commercial multichannel HDR-BT gynecological applicator by rigid incorporation of four GaN-based dosimeters in four channels. Specific methods based on the four GaN dosimeter responses are proposed for accurate determination of dwell time and dwell position inside phantom or applicator. The phantom and the applicator have been tested for HDR-BT QA in routine over two different periods: 29 and 15 days, respectively. Measurements in dwell position and time are compared to the treatment plan. A modified position–time gamma index is used to monitor the quality of treatment delivery. Results: The HDR-BT phantom and the instrumented applicator have been used to determine more than 900 dwell positions over the different testing periods. The errors between the planned and measured dwell positions are 0.11 ± 0.70 mm (1σ) and 0.01 ± 0.42 mm (1σ), with the phantom and the applicator, respectively. The dwell time errors for these positions do not exhibit significant bias, with a standard deviation of less than 100 ms for both systems. The modified position–time gamma index sets a threshold, determining whether the treatment run passes or fails. The error detectability of their systems has been evaluated through tests on intentionally introduced error protocols. With a detection threshold of 0.7 mm, the error detection rate on dwell position is 22% at 0.5 mm, 96% at 1 mm, and 100% at and beyond 1.5 mm. On dwell time with a dwell time threshold of 0.1 s, it is 90% at 0.2 s and 100% at and beyond 0.3 s. Conclusions: The proposed HDR-BT phantom and instrumented applicator have been tested and their main characteristics have been evaluated. These systems perform unsupervised measurements and analysis without prior treatment plan information. They allow independent verification of dwell position and time with accuracy of measurements comparable with other similar systems reported in the literature.« less

Development of a QDots 800 based fluorescent solid phantom for validation of NIRF imaging platforms

NASA Astrophysics Data System (ADS)

Zhu, Banghe; Sevick-Muraca, Eva M.

2013-02-01

Over the past decade, we developed near-infrared fluorescence (NIRF) devices for non-invasive lymphatic imaging using microdosages of ICG in humans and for detection of lymph node metastasis in animal models mimicking metastatic human prostate cancer. To validate imaging, a NIST traceable phantom is needed so that developed "first-inhumans" drugs may be used with different luorescent imaging platforms. In this work, we developed a QDots 800 based fluorescent solid phantom for installation and operational qualification of clinical and preclinical, NIRF imaging devices. Due to its optical clearance, polyurethane was chosen as the base material. Titanium dioxide was used as the scattering agent because of its miscibility in polyurethane. QDots 800 was chosen owing to its stability and NIR emission spectra. A first phantom was constructed for evaluation of the noise floor arising from excitation light leakage, a phenomenon that can be minimized during engineering and design of fluorescent imaging systems. A second set of phantoms were constructed to enable quantification of device sensitivity associated with our preclinical and clinical devices. The phantoms have been successfully applied for installation and operational qualification of our preclinical and clinical devices. Assessment of excitation light leakage provides a figure of merit for "noise floor" and imaging sensitivity can be used to benchmark devices for specific imaging agents.

MAX meets ADAM: a dosimetric comparison between a voxel-based and a mathematical model for external exposure to photons

NASA Astrophysics Data System (ADS)

Kramer, R.; Vieira, J. W.; Khoury, H. J.; Lima, F. de Andrade

2004-03-01

The International Commission on Radiological Protection intends to revise the organ and tissue equivalent dose conversion coefficients published in various reports. For this purpose the mathematical human medical internal radiation dose (MIRD) phantoms, actually in use, have to be replaced by recently developed voxel-based phantoms. This study investigates the dosimetric consequences, especially with respect to the effective male dose, if not only a MIRD phantom is replaced by a voxel phantom, but also if the tissue compositions and the radiation transport codes are changed. This task will be resolved by systematically replacing in the mathematical ADAM/GSF exposure model, first the radiation transport code, then the tissue composition and finally the phantom anatomy, in order to arrive at the voxel-based MAX/EGS4 exposure model. The results show that the combined effect of these replacements can decrease the effective male dose by up to 25% for external exposures to photons for incident energies above 30 keV for different field geometries, mainly because of increased shielding by a heterogeneous skeleton and by the overlying adipose and muscle tissue, and also because of the positions internal organs have in a realistically designed human body compared to their positions in the mathematically constructed phantom.

Dependence of calculus retropulsion dynamics on fiber size and radiant exposure during Ho:YAG lithotripsy.

PubMed

Lee, Ho; Ryan, Robert T; Kim, Jeehyun; Choi, Bernard; Arakeri, Navanit V; Teichman, Joel M H; Welch, A J

2004-08-01

During pulsed laser lithotripsy, the calculus is subject to a strong recoil momentum which moves the calculus away from laser delivery and prolongs the operation. This study was designed to quantify the recoil momentum during Ho:YAG laser lithotripsy. The correlation among crater shape, debris trajectory, laser-induced bubble and recoil momentum was investigated. Calculus phantoms made from plaster of Paris were ablated with free running Ho:YAG lasers. The dynamics of recoil action of a calculus phantom was monitored by a high-speed video camera and the laser ablation craters were examined with Optical Coherent Tomography (OCT). Higher radiant exposure resulted in larger ablation volume (mass) which increased the recoil momentum. Smaller fibers produced narrow craters with a steep contoured geometry and decreased recoil momentum compared to larger fibers. In the presence of water, recoil motion of the phantom deviated from that of phantom in air. Under certain conditions, we observed the phantom rocking towards the fiber after the laser pulse. The shape of the crater is one of the major contributing factors to the diminished recoil momentum of smaller fibers. The re-entrance flow of water induced by the bubble collapse is considered to be the cause of the rocking of the phantom.

Design and optimization of an ultra wideband and compact microwave antenna for radiometric monitoring of brain temperature.

PubMed

Rodrigues, Dario B; Maccarini, Paolo F; Salahi, Sara; Oliveira, Tiago R; Pereira, Pedro J S; Limao-Vieira, Paulo; Snow, Brent W; Reudink, Doug; Stauffer, Paul R

2014-07-01

We present the modeling efforts on antenna design and frequency selection to monitor brain temperature during prolonged surgery using noninvasive microwave radiometry. A tapered log-spiral antenna design is chosen for its wideband characteristics that allow higher power collection from deep brain. Parametric analysis with the software HFSS is used to optimize antenna performance for deep brain temperature sensing. Radiometric antenna efficiency (η) is evaluated in terms of the ratio of power collected from brain to total power received by the antenna. Anatomical information extracted from several adult computed tomography scans is used to establish design parameters for constructing an accurate layered 3-D tissue phantom. This head phantom includes separate brain and scalp regions, with tissue equivalent liquids circulating at independent temperatures on either side of an intact skull. The optimized frequency band is 1.1-1.6 GHz producing an average antenna efficiency of 50.3% from a two turn log-spiral antenna. The entire sensor package is contained in a lightweight and low-profile 2.8 cm diameter by 1.5 cm high assembly that can be held in place over the skin with an electromagnetic interference shielding adhesive patch. The calculated radiometric equivalent brain temperature tracks within 0.4 °C of the measured brain phantom temperature when the brain phantom is lowered 10 °C and then returned to the original temperature (37 °C) over a 4.6-h experiment. The numerical and experimental results demonstrate that the optimized 2.5-cm log-spiral antenna is well suited for the noninvasive radiometric sensing of deep brain temperature.

RPI-AM and RPI-AF, a pair of mesh-based, size-adjustable adult male and female computational phantoms using ICRP-89 parameters and their calculations for organ doses from monoenergetic photon beams

NASA Astrophysics Data System (ADS)

Zhang, Juying; Hum Na, Yong; Caracappa, Peter F.; Xu, X. George

2009-10-01

This paper describes the development of a pair of adult male and adult female computational phantoms that are compatible with anatomical parameters for the 50th percentile population as specified by the International Commission on Radiological Protection (ICRP). The phantoms were designed entirely using polygonal mesh surfaces—a Boundary REPresentation (BREP) geometry that affords the ability to efficiently deform the shape and size of individual organs, as well as the body posture. A set of surface mesh models, from Anatomium™ 3D P1 V2.0, including 140 organs (out of 500 available) was adopted to supply the basic anatomical representation at the organ level. The organ masses were carefully adjusted to agree within 0.5% relative error with the reference values provided in the ICRP Publication 89. The finalized phantoms have been designated the RPI adult male (RPI-AM) and adult female (RPI-AF) phantoms. For the purposes of organ dose calculations using the MCNPX Monte Carlo code, these phantoms were subsequently converted to voxel formats. Monoenergetic photons between 10 keV and 10 MeV in six standard external photon source geometries were considered in this study: four parallel beams (anterior-posterior, posterior-anterior, left lateral and right lateral), one rotational and one isotropic. The results are tabulated as fluence-to-organ-absorbed-dose conversion coefficients and fluence-to-effective-dose conversion coefficients and compared against those derived from the ICRP computational phantoms, REX and REGINA. A general agreement was found for the effective dose from these two sets of phantoms for photon energies greater than about 300 keV. However, for low-energy photons and certain individual organs, the absorbed doses exhibit profound differences due to specific anatomical features. For example, the position of the arms affects the dose to the lung by more than 20% below 300 keV in the lateral source directions, and the vertical position of the testes affects the dose by more than 80% below 150 keV in the PA source direction. The deformability and adjustability of organs and posture in the RPI adult phantoms may prove useful not only for average workers or patients for radiation protection purposes, but also in studies involving anatomical and posture variability that is important in future radiation protection dosimetry.

A medical device-grade T1 and ECV phantom for global T1 mapping quality assurance-the T1 Mapping and ECV Standardization in cardiovascular magnetic resonance (T1MES) program.

PubMed

Captur, Gabriella; Gatehouse, Peter; Keenan, Kathryn E; Heslinga, Friso G; Bruehl, Ruediger; Prothmann, Marcel; Graves, Martin J; Eames, Richard J; Torlasco, Camilla; Benedetti, Giulia; Donovan, Jacqueline; Ittermann, Bernd; Boubertakh, Redha; Bathgate, Andrew; Royet, Celine; Pang, Wenjie; Nezafat, Reza; Salerno, Michael; Kellman, Peter; Moon, James C

2016-09-22

T 1 mapping and extracellular volume (ECV) have the potential to guide patient care and serve as surrogate end-points in clinical trials, but measurements differ between cardiovascular magnetic resonance (CMR) scanners and pulse sequences. To help deliver T 1 mapping to global clinical care, we developed a phantom-based quality assurance (QA) system for verification of measurement stability over time at individual sites, with further aims of generalization of results across sites, vendor systems, software versions and imaging sequences. We thus created T1MES: The T1 Mapping and ECV Standardization Program. A design collaboration consisting of a specialist MRI small-medium enterprise, clinicians, physicists and national metrology institutes was formed. A phantom was designed covering clinically relevant ranges of T 1 and T 2 in blood and myocardium, pre and post-contrast, for 1.5 T and 3 T. Reproducible mass manufacture was established. The device received regulatory clearance by the Food and Drug Administration (FDA) and Conformité Européene (CE) marking. The T1MES phantom is an agarose gel-based phantom using nickel chloride as the paramagnetic relaxation modifier. It was reproducibly specified and mass-produced with a rigorously repeatable process. Each phantom contains nine differently-doped agarose gel tubes embedded in a gel/beads matrix. Phantoms were free of air bubbles and susceptibility artifacts at both field strengths and T 1 maps were free from off-resonance artifacts. The incorporation of high-density polyethylene beads in the main gel fill was effective at flattening the B 1 field. T 1 and T 2 values measured in T1MES showed coefficients of variation of 1 % or less between repeat scans indicating good short-term reproducibility. Temperature dependency experiments confirmed that over the range 15-30 °C the short-T 1 tubes were more stable with temperature than the long-T 1 tubes. A batch of 69 phantoms was mass-produced with random sampling of ten of these showing coefficients of variations for T 1 of 0.64 ± 0.45 % and 0.49 ± 0.34 % at 1.5 T and 3 T respectively. The T1MES program has developed a T 1 mapping phantom to CE/FDA manufacturing standards. An initial 69 phantoms with a multi-vendor user manual are now being scanned fortnightly in centers worldwide. Future results will explore T 1 mapping sequences, platform performance, stability and the potential for standardization.

Hood River Passive House, Hood River, Oregon (Fact Sheet)

DOE Office of Scientific and Technical Information (OSTI.GOV)

None, None

2014-02-01

The Hood River Passive Project was developed by Root Design Build of Hood River Oregon using the Passive House Planning Package (PHPP) to meet all of the requirements for certification under the European Passive House standards. The Passive House design approach has been gaining momentum among residential designers for custom homes and BEopt modeling indicates that these designs may actually exceed the goal of the U.S. Department of Energy's (DOE) Building America program to "reduce home energy use by 30%-50%" (compared to 2009 energy codes for new homes). This report documents the short term test results of the Shift Housemore » and compares the results of PHPP and BEopt modeling of the project. The design includes high R-Value assemblies, extremely tight construction, high performance doors and windows, solar thermal DHW, heat recovery ventilation, moveable external shutters and a high performance ductless mini-split heat pump. Cost analysis indicates that many of the measures implemented in this project did not meet the BA standard for cost neutrality. The ductless mini-split heat pump, lighting and advanced air leakage control were the most cost effective measures. The future challenge will be to value engineer the performance levels indicated here in modeling using production based practices at a significantly lower cost.« less

New Whole-House Solutions Case Study: Hood River Passive House

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

2014-02-01

The Hood River Passive Project was developed by Root Design Build of Hood River Oregon using the Passive House Planning Package (PHPP) to meet all of the requirements for certification under the European Passive House standards. The Passive House design approach has been gaining momentum among residential designers for custom homes and BEopt modeling indicates that these designs may actually exceed the goal of the U.S. Department of Energy's (DOE) Building America program to "reduce home energy use by 30%-50%" (compared to 2009 energy codes for new homes). This report documents the short term test results of the Shift Housemore » and compares the results of PHPP and BEopt modeling of the project. The design includes high R-Value assemblies, extremely tight construction, high performance doors and windows, solar thermal DHW, heat recovery ventilation, moveable external shutters and a high performance ductless mini-split heat pump. Cost analysis indicates that many of the measures implemented in this project did not meet the BA standard for cost neutrality. The ductless mini-split heat pump, lighting and advanced air leakage control were the most cost effective measures. The future challenge will be to value engineer the performance levels indicated here in modeling using production based practices at a significantly lower cost.« less

Multilayered tissue mimicking skin and vessel phantoms with tunable mechanical, optical, and acoustic properties

PubMed Central

Chen, Alvin I.; Balter, Max L.; Chen, Melanie I.; Gross, Daniel; Alam, Sheikh K.; Maguire, Timothy J.; Yarmush, Martin L.

2016-01-01

Purpose: This paper describes the design, fabrication, and characterization of multilayered tissue mimicking skin and vessel phantoms with tunable mechanical, optical, and acoustic properties. The phantoms comprise epidermis, dermis, and hypodermis skin layers, blood vessels, and blood mimicking fluid. Each tissue component may be individually tailored to a range of physiological and demographic conditions. Methods: The skin layers were constructed from varying concentrations of gelatin and agar. Synthetic melanin, India ink, absorbing dyes, and Intralipid were added to provide optical absorption and scattering in the skin layers. Bovine serum albumin was used to increase acoustic attenuation, and 40 μm diameter silica microspheres were used to induce acoustic backscatter. Phantom vessels consisting of thin-walled polydimethylsiloxane tubing were embedded at depths of 2–6 mm beneath the skin, and blood mimicking fluid was passed through the vessels. The phantoms were characterized through uniaxial compression and tension experiments, rheological frequency sweep studies, diffuse reflectance spectroscopy, and ultrasonic pulse-echo measurements. Results were then compared to in vivo and ex vivo literature data. Results: The elastic and dynamic shear behavior of the phantom skin layers and vessel wall closely approximated the behavior of porcine skin tissues and human vessels. Similarly, the optical properties of the phantom tissue components in the wavelength range of 400–1100 nm, as well as the acoustic properties in the frequency range of 2–9 MHz, were comparable to human tissue data. Normalized root mean square percent errors between the phantom results and the literature reference values ranged from 1.06% to 9.82%, which for many measurements were less than the sample variability. Finally, the mechanical and imaging characteristics of the phantoms were found to remain stable after 30 days of storage at 21 °C. Conclusions: The phantoms described in this work simulate the mechanical, optical, and acoustic properties of human skin tissues, vessel tissue, and blood. In this way, the phantoms are uniquely suited to serve as test models for multimodal imaging techniques and image-guided interventions. PMID:27277058

Electrode Arrangement As Substitute Bottom For An Electrothermic Slag Smelting Furnace.

DOEpatents

Aune, Jan Arthur; Brinch, Jon Christian; Johansen, Kai

2005-12-27

The electrode arrangement uses vertically oriented electrodes with side wall contacts for an electrothermic smelting furnace for aluminum production. The side wall contacts are radially moveable into the furnace to compensate for wear on the contacts. The side wall contacts can be hollow to allow a slag forming charge to be fed to the furnace.

Reaching a Moveable Visual Target: Dissociations in Brain Tumour Patients

ERIC Educational Resources Information Center

Buiatti, Tania; Skrap, Miran; Shallice, Tim

2013-01-01

Damage to the posterior parietal cortex (PPC) can lead to Optic Ataxia (OA), in which patients misreach to peripheral targets. Recent research suggested that the PPC might be involved not only in simple reaching tasks toward peripheral targets, but also in changing the hand movement trajectory in real time if the target moves. The present study…

49 CFR 213.235 - Inspection of switches, track crossings, and lift rail assemblies or other transition devices on...

Code of Federal Regulations, 2013 CFR

2013-10-01

... 49 Transportation 4 2013-10-01 2013-10-01 false Inspection of switches, track crossings, and lift... TRANSPORTATION TRACK SAFETY STANDARDS Inspection § 213.235 Inspection of switches, track crossings, and lift rail... section, each switch, turnout, track crossing, and moveable bridge lift rail assembly or other transition...

49 CFR 213.235 - Inspection of switches, track crossings, and lift rail assemblies or other transition devices on...

Code of Federal Regulations, 2014 CFR

2014-10-01

... 49 Transportation 4 2014-10-01 2014-10-01 false Inspection of switches, track crossings, and lift... TRANSPORTATION TRACK SAFETY STANDARDS Inspection § 213.235 Inspection of switches, track crossings, and lift rail... section, each switch, turnout, track crossing, and moveable bridge lift rail assembly or other transition...

49 CFR 213.235 - Inspection of switches, track crossings, and lift rail assemblies or other transition devices on...

Code of Federal Regulations, 2012 CFR

2012-10-01

... 49 Transportation 4 2012-10-01 2012-10-01 false Inspection of switches, track crossings, and lift... TRANSPORTATION TRACK SAFETY STANDARDS Inspection § 213.235 Inspection of switches, track crossings, and lift rail... section, each switch, turnout, track crossing, and moveable bridge lift rail assembly or other transition...

49 CFR 213.235 - Inspection of switches, track crossings, and lift rail assemblies or other transition devices on...

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 4 2010-10-01 2010-10-01 false Inspection of switches, track crossings, and lift... TRANSPORTATION TRACK SAFETY STANDARDS Inspection § 213.235 Inspection of switches, track crossings, and lift rail... section, each switch, turnout, track crossing, and moveable bridge lift rail assembly or other transition...

49 CFR 213.235 - Inspection of switches, track crossings, and lift rail assemblies or other transition devices on...

Code of Federal Regulations, 2011 CFR

2011-10-01

... 49 Transportation 4 2011-10-01 2011-10-01 false Inspection of switches, track crossings, and lift... TRANSPORTATION TRACK SAFETY STANDARDS Inspection § 213.235 Inspection of switches, track crossings, and lift rail... section, each switch, turnout, track crossing, and moveable bridge lift rail assembly or other transition...

Electrostatic MEMS devices with high reliability

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goldsmith, Charles L; Auciello, Orlando H; Sumant, Anirudha V

The present invention provides for an electrostatic microelectromechanical (MEMS) device comprising a dielectric layer separating a first conductor and a second conductor. The first conductor is moveable towards the second conductor, when a voltage is applied to the MEMS device. The dielectric layer recovers from dielectric charging failure almost immediately upon removal of the voltage from the MEMS device.

A Moveable Feast--A Progressive Approach to the Unit Operations Laboratory

ERIC Educational Resources Information Center

Conner, Wm. Curtis, Jr.; Hammond, Karl D.; Laurence, Robert L.

2011-01-01

The authors describe an alternative format for the senior laboratory in which students are allowed--indeed, expected--to communicate with previous groups and build on their results. The effect is a unit operations laboratory in which students are empowered to propose the experiments they wish to do and in which the cumulative experience of the…

Ignition behavior of live California chaparral leaves

Treesearch

J.D. Engstrom; J.K Butler; S.G. Smith; L.L. Baxter; T.H. Fletcher; D.R. Weise

2004-01-01

Current forest fire models are largely empirical correlations based on data from beds of dead vegetation Improvement in model capabilities is sought by developing models of the combustion of live fuels. A facility was developed to determine the combustion behavior of small samples of live fuels, consisting of a flat-flame burner on a moveable platform Qualitative and...

Deformable torso phantoms of Chinese adults for personalized anatomy modelling.

PubMed

Wang, Hongkai; Sun, Xiaobang; Wu, Tongning; Li, Congsheng; Chen, Zhonghua; Liao, Meiying; Li, Mengci; Yan, Wen; Huang, Hui; Yang, Jia; Tan, Ziyu; Hui, Libo; Liu, Yue; Pan, Hang; Qu, Yue; Chen, Zhaofeng; Tan, Liwen; Yu, Lijuan; Shi, Hongcheng; Huo, Li; Zhang, Yanjun; Tang, Xin; Zhang, Shaoxiang; Liu, Changjian

2018-04-16

In recent years, there has been increasing demand for personalized anatomy modelling for medical and industrial applications, such as ergonomics device development, clinical radiological exposure simulation, biomechanics analysis, and 3D animation character design. In this study, we constructed deformable torso phantoms that can be deformed to match the personal anatomy of Chinese male and female adults. The phantoms were created based on a training set of 79 trunk computed tomography (CT) images (41 males and 38 females) from normal Chinese subjects. Major torso organs were segmented from the CT images, and the statistical shape model (SSM) approach was used to learn the inter-subject anatomical variations. To match the personal anatomy, the phantoms were registered to individual body surface scans or medical images using the active shape model method. The constructed SSM demonstrated anatomical variations in body height, fat quantity, respiratory status, organ geometry, male muscle size, and female breast size. The masses of the deformed phantom organs were consistent with Chinese population organ mass ranges. To validate the performance of personal anatomy modelling, the phantoms were registered to the body surface scan and CT images. The registration accuracy measured from 22 test CT images showed a median Dice coefficient over 0.85, a median volume recovery coefficient (RC vlm ) between 0.85 and 1.1, and a median averaged surface distance (ASD) < 1.5 mm. We hope these phantoms can serve as computational tools for personalized anatomy modelling for the research community. © 2018 Anatomical Society.

Semipermeable Hollow Fiber Phantoms for Development and Validation of Perfusion-Sensitive MR Methods and Signal Models

PubMed Central

Anderson, J.R.; Ackerman, J.J.H.; Garbow, J.R.

2015-01-01

Two semipermeable, hollow fiber phantoms for the validation of perfusion-sensitive magnetic resonance methods and signal models are described. Semipermeable hollow fibers harvested from a standard commercial hemodialysis cartridge serve to mimic tissue capillary function. Flow of aqueous media through the fiber lumen is achieved with a laboratory-grade peristaltic pump. Diffusion of water and solute species (e.g., Gd-based contrast agent) occurs across the fiber wall, allowing exchange between the lumen and the extralumenal space. Phantom design attributes include: i) small physical size, ii) easy and low-cost construction, iii) definable compartment volumes, and iv) experimental control over media content and flow rate. PMID:26167136

Experimental platform for intra-uterine needle placement procedures

NASA Astrophysics Data System (ADS)

Madjidi, Yashar; Haidegger, Tamás.; Ptacek, Wolfgang; Berger, Daniel; Kirisits, Christian; Kronreif, Gernot; Fichtinger, Gabor

2013-03-01

A framework has been investigated to enable a variety of comparative studies in the context of needle-based gynaecological brachytherapy. Our aim was to create an anthropomorphic phantom-based platform. The three main elements of the platform are the organ model, needle guide, and needle drive. These have been studied and designed to replicate the close environment of brachytherapy treatment for cervical cancer. Key features were created with the help of collaborating interventional radio-oncologists and the observations made in the operating room. A phantom box, representing the uterus model, has been developed considering available surgical analogies and operational limitations, such as organs at risk. A modular phantom-based platform has been designed and prototyped with the capability of providing various boundary conditions for the target organ. By mimicking the female pelvic floor, this framework has been used to compare a variety of needle insertion techniques and configurations for cervical and uterine interventions. The results showed that the proposed methodology is useful for the investigation of quantifiable experiments in the intraabdominal and pelvic regions.

Evaluation of a simulation procedure designed to recognize shape and contour of suspicious masses in mammography

NASA Astrophysics Data System (ADS)

Sousa, Maria A. Z.; Siqueira, Paula N.; Schiabel, Homero

2015-03-01

A large number of breast phantoms have been developed for conducting quality tests, characterization of imaging systems and computer aided diagnosis schemes, dosimetry and image perception. The realism of these phantoms is important for ensuring the accuracy of results and a greater range of applications. In this work, a developed phantom is considered proposing the use of PVC films for simulation of nodules inserted in the breast parenchyma designed for classification between malignant and benign signals according to the BI-RADS® standard. The investigation includes analysis of radiographic density, mass shape and its corresponding contour outlined by experienced radiologists. The material was cut based on lesions margins found in 44 clinical cases, which were divided between circumscribed and spiculated structures. Tests were performed to check the ability of the specialists in distinguishing the contour compared to actual cases while the shapes accuracy was determined quantitatively by evaluation metrics. Results showed the applicability of the chosen material creating image radiological patterns very similar to the actual ones.

Design and implementation of a 3D-MR/CT geometric image distortion phantom/analysis system for stereotactic radiosurgery.

PubMed

Damyanovich, A Z; Rieker, M; Zhang, B; Bissonnette, J-P; Jaffray, D A

2018-03-27

The design, construction and application of a multimodality, 3D magnetic resonance/computed tomography (MR/CT) image distortion phantom and analysis system for stereotactic radiosurgery (SRS) is presented. The phantom is characterized by (1) a 1 × 1 × 1 (cm) 3 MRI/CT-visible 3D-Cartesian grid; (2) 2002 grid vertices that are 3D-intersections of MR-/CT-visible 'lines' in all three orthogonal planes; (3) a 3D-grid that is MR-signal positive/CT-signal negative; (4) a vertex distribution sufficiently 'dense' to characterize geometrical parameters properly, and (5) a grid/vertex resolution consistent with SRS localization accuracy. When positioned correctly, successive 3D-vertex planes along any orthogonal axis of the phantom appear as 1 × 1 (cm) 2 -2D grids, whereas between vertex planes, images are defined by 1 × 1 (cm) 2 -2D arrays of signal points. Image distortion is evaluated using a centroid algorithm that automatically identifies the center of each 3D-intersection and then calculates the deviations dx, dy, dz and dr for each vertex point; the results are presented as a color-coded 2D or 3D distribution of deviations. The phantom components and 3D-grid are machined to sub-millimeter accuracy, making the device uniquely suited to SRS applications; as such, we present it here in a form adapted for use with a Leksell stereotactic frame. Imaging reproducibility was assessed via repeated phantom imaging across ten back-to-back scans; 80%-90% of the differences in vertex deviations dx, dy, dz and dr between successive 3 T MRI scans were found to be  ⩽0.05 mm for both axial and coronal acquisitions, and over  >95% of the differences were observed to be  ⩽0.05 mm for repeated CT scans, clearly demonstrating excellent reproducibility. Applications of the 3D-phantom/analysis system are presented, using a 32-month time-course assessment of image distortion/gradient stability and statistical control chart for 1.5 T and 3 T GE TwinSpeed MRI systems.

Effect of elemental compositions on Monte Carlo dose calculations in proton therapy of eye tumors

NASA Astrophysics Data System (ADS)

Rasouli, Fatemeh S.; Farhad Masoudi, S.; Keshazare, Shiva; Jette, David

2015-12-01

Recent studies in eye plaque brachytherapy have found considerable differences between the dosimetric results by using a water phantom, and a complete human eye model. Since the eye continues to be simulated as water-equivalent tissue in the proton therapy literature, a similar study for investigating such a difference in treating eye tumors by protons is indispensable. The present study inquires into this effect in proton therapy utilizing Monte Carlo simulations. A three-dimensional eye model with elemental compositions is simulated and used to examine the dose deposition to the phantom. The beam is planned to pass through a designed beam line to moderate the protons to the desired energies for ocular treatments. The results are compared with similar irradiation to a water phantom, as well as to a material with uniform density throughout the whole volume. Spread-out Bragg peaks (SOBPs) are created by adding pristine peaks to cover a typical tumor volume. Moreover, the corresponding beam parameters recommended by the ICRU are calculated, and the isodose curves are computed. The results show that the maximum dose deposited in ocular media is approximately 5-7% more than in the water phantom, and about 1-1.5% less than in the homogenized material of density 1.05 g cm-3. Furthermore, there is about a 0.2 mm shift in the Bragg peak due to the tissue composition difference between the models. It is found that using the weighted dose profiles optimized in a water phantom for the realistic eye model leads to a small disturbance of the SOBP plateau dose. In spite of the plaque brachytherapy results for treatment of eye tumors, it is found that the differences between the simplified models presented in this work, especially the phantom containing the homogenized material, are not clinically significant in proton therapy. Taking into account the intrinsic uncertainty of the patient dose calculation for protons, and practical problems corresponding to applying patient-specific eye modeling, we found that the results of using a generic phantom containing homogenized material for proton therapy of eye tumors can be satisfactory for designing the beam.

Design and implementation of a 3D-MR/CT geometric image distortion phantom/analysis system for stereotactic radiosurgery

NASA Astrophysics Data System (ADS)

Damyanovich, A. Z.; Rieker, M.; Zhang, B.; Bissonnette, J.-P.; Jaffray, D. A.

2018-04-01

The design, construction and application of a multimodality, 3D magnetic resonance/computed tomography (MR/CT) image distortion phantom and analysis system for stereotactic radiosurgery (SRS) is presented. The phantom is characterized by (1) a 1 × 1 × 1 (cm)3 MRI/CT-visible 3D-Cartesian grid; (2) 2002 grid vertices that are 3D-intersections of MR-/CT-visible ‘lines’ in all three orthogonal planes; (3) a 3D-grid that is MR-signal positive/CT-signal negative; (4) a vertex distribution sufficiently ‘dense’ to characterize geometrical parameters properly, and (5) a grid/vertex resolution consistent with SRS localization accuracy. When positioned correctly, successive 3D-vertex planes along any orthogonal axis of the phantom appear as 1 × 1 (cm)2-2D grids, whereas between vertex planes, images are defined by 1 × 1 (cm)2-2D arrays of signal points. Image distortion is evaluated using a centroid algorithm that automatically identifies the center of each 3D-intersection and then calculates the deviations dx, dy, dz and dr for each vertex point; the results are presented as a color-coded 2D or 3D distribution of deviations. The phantom components and 3D-grid are machined to sub-millimeter accuracy, making the device uniquely suited to SRS applications; as such, we present it here in a form adapted for use with a Leksell stereotactic frame. Imaging reproducibility was assessed via repeated phantom imaging across ten back-to-back scans; 80%–90% of the differences in vertex deviations dx, dy, dz and dr between successive 3 T MRI scans were found to be  ⩽0.05 mm for both axial and coronal acquisitions, and over  >95% of the differences were observed to be  ⩽0.05 mm for repeated CT scans, clearly demonstrating excellent reproducibility. Applications of the 3D-phantom/analysis system are presented, using a 32-month time-course assessment of image distortion/gradient stability and statistical control chart for 1.5 T and 3 T GE TwinSpeed MRI systems.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gaballa, H; O’Brien, M; Riegel, A

Purpose: To develop a daily quality assurance (QA) device that can test the 6DoF (degrees of freedom) couch repositioning accuracy, prior to SBRT treatment deliveries, with an accuracy of ±0.3 degrees and ±0.3 mm. Methods: A daily QA phantom is designed with a focus on the derived center of projections of its markers, rather than tracking its individual markers one at a time. This approach can be the most favorable to address the intended machining accuracy of the QA phantom and the CBCT spatial resolution limitations, primarily 1 mm min slice thickness, simultaneously. With the current design, ±0.1 mm congruencemore » of the resultant center of gravity of the markers with reference CT (0.6 mm minimum slice thickness) vs CBCT (1.0 mm minimum slice thickness) can be achieved. If successful, the QA device should be qualified to test 6DoF couch performance with a gauged accuracy of ±0.3 degrees/±0.3 mm. Testing is performed for the Varian True Beam 2.0 6DoF system. Results: Once the QA phantom is constructed and tested, agreement of the center of gravity of the reference CT scan and the CBCT scan of ±0.1 mm is achieved. This has translated into a consistent 3D-3D match on the treatment machine, CT vs CBCT, with a repetitive ±0.1 mm variation, thus exceeding our expectations. We have deployed the phantom for daily QA on one of our accelerators, and found that the QA time has increased by only 10 minutes. Conclusion: A 6DoF phantom has been designed (patent pending) and built with a realistic work flow in mind where the daily couch accuracy QA checks taking less than 10 minutes. Current developments include integration with the Varian’s Machine Performance Check consistency module.« less

Dosimetric study of the protection level of the bone marrow in patients with cervical or endometrial cancer for three radiotherapy techniques - 3D CRT, IMRT and VMAT. Study protocol.

NASA Astrophysics Data System (ADS)

Jodda, Agata; Urbański, Bartosz; Piotrowski, Tomasz; Malicki, Julian

2016-03-01

Background: The paper shows the methodology of an in-phantom study of the protection level of the bone marrow in patients with cervical or endometrial cancer for three radiotherapy techniques: three-dimensional conformal radiotherapy, intensity modulated radiotherapy, and volumetric modulated arc therapy, preceded by the procedures of image guidance. Methods/Design: The dosimetric evaluation of the doses will be performed in an in-house multi-element anthropomorphic phantom of the female pelvic area created by three-dimensional printing technology. The volume and position of the structures will be regulated according to the guidelines from the Bayesian network. The input data for the learning procedure of the model will be obtained from the retrospective analysis of imaging data obtained for 96 patients with endometrial cancer or cervical cancer treated with radiotherapy in our centre in 2008-2013. Three anatomical representations of the phantom simulating three independent clinical cases will be chosen. Five alternative treatment plans (1 × three-dimensional conformal radiotherapy, 2 × intensity modulated radiotherapy and 2 × volumetric modulated arc therapy) will be created for each representation. To simulate image-guided radiotherapy, ten specific recombinations will be designated, for each anatomical representation separately, reflecting possible changes in the volume and position of the phantom components. Discussion: The comparative analysis of planned measurements will identify discrepancies between calculated doses and doses that were measured in the phantom. Finally, differences between the doses cumulated in the hip plates performed by different techniques simulating the gynaecological patients' irradiation of dose delivery will be established. The results of this study will form the basis of the prospective clinical trial that will be designed for the assessment of hematologic toxicity and its correlation with the doses cumulated in the hip plates, for gynaecologic patients undergoing radiation therapy.

MR-CBCT image-guided system for radiotherapy of orthotopic rat prostate tumors.

PubMed

Chiu, Tsuicheng D; Arai, Tatsuya J; Campbell Iii, James; Jiang, Steve B; Mason, Ralph P; Stojadinovic, Strahinja

2018-01-01

Multi-modality image-guided radiotherapy is the standard of care in contemporary cancer management; however, it is not common in preclinical settings due to both hardware and software limitations. Soft tissue lesions, such as orthotopic prostate tumors, are difficult to identify using cone beam computed tomography (CBCT) imaging alone. In this study, we characterized a research magnetic resonance (MR) scanner for preclinical studies and created a protocol for combined MR-CBCT image-guided small animal radiotherapy. Two in-house dual-modality, MR and CBCT compatible, phantoms were designed and manufactured using 3D printing technology. The phantoms were used for quality assurance tests and to facilitate end-to-end testing for combined preclinical MR and CBCT based treatment planning. MR and CBCT images of the phantoms were acquired utilizing a Varian 4.7 T scanner and XRad-225Cx irradiator, respectively. The geometry distortion was assessed by comparing MR images to phantom blueprints and CBCT. The corrected MR scans were co-registered with CBCT and subsequently used for treatment planning. The fidelity of 3D printed phantoms compared to the blueprint design yielded favorable agreement as verified with the CBCT measurements. The geometric distortion, which varied between -5% and 11% throughout the scanning volume, was substantially reduced to within 0.4% after correction. The distortion free MR images were co-registered with the corresponding CBCT images and imported into a commercial treatment planning software SmART Plan. The planning target volume (PTV) was on average 19% smaller when contoured on the corrected MR-CBCT images relative to raw images without distortion correction. An MR-CBCT based preclinical workflow was successfully designed and implemented for small animal radiotherapy. Combined MR-CBCT image-guided radiotherapy for preclinical research potentially delivers enhanced relevance to human radiotherapy for various disease sites. This novel protocol is wide-ranging and not limited to the orthotopic prostate tumor study presented in the study.

Experimental assessment of the Advanced Collapsed-cone Engine for scalp brachytherapy treatments.

PubMed

Cawston-Grant, Brie; Morrison, Hali; Sloboda, Ron S; Menon, Geetha

To experimentally assess the performance of the Advanced Collapsed-cone Engine (ACE) for 192 Ir high-dose-rate brachytherapy treatment planning of nonmelanoma skin cancers of the scalp. A layered slab phantom was designed to model the head (skin, skull, and brain) and surface treatment mold using tissue equivalent materials. Six variations of the phantom were created by varying skin thickness, skull thickness, and size of air gap between the mold and skin. Treatment planning was initially performed using the Task Group 43 (TG-43) formalism with CT images of each phantom variation. Doses were recalculated using standard and high accuracy modes of ACE. The plans were delivered to Gafchromic EBT3 film placed between different layers of the phantom. Doses calculated by TG-43 and ACE and those measured by film agreed with each other at most locations within the phantoms. For a given phantom variation, average TG-43- and ACE-calculated doses were similar, with a maximum difference of (3 ± 12)% (k = 2). Compared to the film measurements, TG-43 and ACE overestimated the film-measured dose by (13 ± 12)% (k = 2) for one phantom variation below the skull layer. TG-43- and ACE-calculated and film-measured doses were found to agree above the skull layer of the phantom, which is where the tumor would be located in a clinical case. ACE appears to underestimate the attenuation through bone relative to that measured by film; however, the dose to bone is below tolerance levels for this treatment. Copyright © 2017 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

SU-F-207-16: CT Protocols Optimization Using Model Observer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tseng, H; Fan, J; Kupinski, M

2015-06-15

Purpose: To quantitatively evaluate the performance of different CT protocols using task-based measures of image quality. This work studies the task of size and the contrast estimation of different iodine concentration rods inserted in head- and body-sized phantoms using different imaging protocols. These protocols are designed to have the same dose level (CTDIvol) but using different X-ray tube voltage settings (kVp). Methods: Different concentrations of iodine objects inserted in a head size phantom and a body size phantom are imaged on a 64-slice commercial CT scanner. Scanning protocols with various tube voltages (80, 100, and 120 kVp) and current settingsmore » are selected, which output the same absorbed dose level (CTDIvol). Because the phantom design (size of the iodine objects, the air gap between the inserted objects and the phantom) is not ideal for a model observer study, the acquired CT images are used to generate simulation images with four different sizes and five different contracts iodine objects. For each type of the objects, 500 images (100 x 100 pixels) are generated for the observer study. The observer selected in this study is the channelized scanning linear observer which could be applied to estimate the size and the contrast. The figure of merit used is the correct estimation ratio. The mean and the variance are estimated by the shuffle method. Results: The results indicate that the protocols with 100 kVp tube voltage setting provides the best performance for iodine insert size and contrast estimation for both head and body phantom cases. Conclusion: This work presents a practical and robust quantitative approach using channelized scanning linear observer to study contrast and size estimation performance from different CT protocols. Different protocols at same CTDIvol setting could Result in different image quality performance. The relationship between the absorbed dose and the diagnostic image quality is not linear.« less

TH-AB-209-12: Tissue Equivalent Phantom with Excised Human Tissue for Assessing Clinical Capabilities of Coherent Scatter Imaging Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Albanese, K; Morris, R; Spencer, J

Purpose: Previously we reported the development of anthropomorphic tissue-equivalent scatter phantoms of the human breast. Here we present the first results from the scatter imaging of the tissue equivalent breast phantoms for breast cancer diagnosis. Methods: A breast phantom was designed to assess the capability of coded aperture coherent x-ray scatter imaging to classify different types of breast tissue (adipose, fibroglandular, tumor). The phantom geometry was obtained from a prone breast geometry scanned on a dedicated breast CT system. The phantom was 3D printed using the segmented DICOM breast CT data. The 3D breast phantom was filled with lard (asmore » a surrogate for adipose tissue) and scanned in different geometries alongside excised human breast tissues (obtained from lumpectomy and mastectomy procedures). The raw data were reconstructed using a model-based reconstruction algorithm and yielded the location and form factor (i.e., momentum transfer (q) spectrum) of the materials that were imaged. The measured material form factors were then compared to the ground truth measurements acquired by x-ray diffraction (XRD) imaging. Results: Our scatter imaging system was able to define the location and composition of the various materials and tissues within the phantom. Cancerous breast tissue was detected and classified through automated spectral matching and an 86% correlation threshold. The total scan time for the sample was approximately 10 minutes and approaches workflow times for clinical use in intra-operative or other diagnostic tasks. Conclusion: This work demonstrates the first results from an anthropomorphic tissue equivalent scatter phantom to characterize a coherent scatter imaging system. The functionality of the system shows promise in applications such as intra-operative margin detection or virtual biopsy in the diagnosis of breast cancer. Future work includes using additional patient-derived tissues (e.g., human fat), and modeling additional organs (e.g., lung).« less

SU-E-T-282: Dose Measurements with An End-To-End Audit Phantom for Stereotactic Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jones, R; Artschan, R; Thwaites, D

Purpose: Report on dose measurements as part of an end-to-end test for stereotactic radiotherapy, using a new audit tool, which allows audits to be performed efficiently either by an onsite team or as a postal audit. Methods: Film measurements have been performed with a new Stereotactic Cube Phantom. The phantom has been designed to perform Winston Lutz type position verification measurements and dose measurements in one setup. It comprises a plastic cube with a high density ball in its centre (used for MV imaging with film or EPID) and low density markers in the periphery (used for Cone Beam Computedmore » Tomography, CBCT imaging). It also features strategically placed gold markers near the posterior and right surfaces, which can be used to calculate phantom rotations on MV images. Slit-like openings allow insertion of film or other detectors.The phantom was scanned and small field treatment plans were created. The fields do not traverse any inhomogeneities of the phantom on their paths to the measurement location. The phantom was setup at the delivery system using CBCT imaging. The calculated treatment fields were delivered, each with a piece of radiochromic film (EBT3) placed in the anterior film holder of the phantom. MU had been selected in planning to achieve similar exposures on all films. Calibration films were exposed in solid water for dose levels around the expected doses. Films were scanned and analysed following established procedures. Results: Setup of the cube showed excellent suitability for CBCT 3D alignment. MV imaging with EPID allowed for clear identification of all markers. Film based dose measurements showed good agreement for MLC created fields down to 0.5 mm × 0.5 mm. Conclusion: An end-to-end audit phantom for stereotactic radiotherapy has been developed and tested.« less

SU-F-I-37: How Fat Distribution and Table Height Affect Estimates of Patient Size in CT Scanning: A Phantom Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Silosky, M; Marsh, R

Purpose: Localizer projection radiographs acquired prior to CT scans are used to estimate patient size, affecting the function of Automatic Tube Current Modulation (ATCM) and hence CTDIvol and SSDE. Due to geometric effects, the projected patient size varies with scanner table height and with the orientation of the localizer (AP versus PA). This study sought to determine if patient size estimates made from localizer scans is affected by variations in fat distribution, specifically when the widest part of the patient is not at the geometric center of the patient. Methods: Lipid gel bolus material was wrapped around an anthropomorphic phantommore » to simulate two different body mass distributions. The first represented a patient with fairly rigid fat and had a generally oval shape. The second was bell-shaped, representing corpulent patients more susceptible to gravity’s lustful tug. Each phantom configuration was imaged using an AP localizer and then a PA localizer. This was repeated at various scanner table heights. The width of the phantom was measured from the localizer and diagnostic images using in-house software. Results: 1) The projected phantom width varied up to 39% as table height changed.2) At some table heights, the width of the phantom, designed to represent larger patients, exceeded the localizer field of view, resulting in an underestimation of the phantom width.3) The oval-shaped phantom approached a normalized phantom width of 1 at a table height several centimeters lower (AP localizer) or higher (PA localizer) than did the bell-shaped phantom. Conclusion: Accurate estimation of patient size from localizer scans is dependent on patient positioning with respect to scanner isocenter and is limited in large patients. Further, patient size is more accurately measured on projection images if the widest part of the patient, rather than the geometric center of the patient, is positioned at scanner isocenter.« less

3D Rapid Prototyping for Otolaryngology-Head and Neck Surgery: Applications in Image-Guidance, Surgical Simulation and Patient-Specific Modeling.

PubMed

Chan, Harley H L; Siewerdsen, Jeffrey H; Vescan, Allan; Daly, Michael J; Prisman, Eitan; Irish, Jonathan C

2015-01-01

The aim of this study was to demonstrate the role of advanced fabrication technology across a broad spectrum of head and neck surgical procedures, including applications in endoscopic sinus surgery, skull base surgery, and maxillofacial reconstruction. The initial case studies demonstrated three applications of rapid prototyping technology are in head and neck surgery: i) a mono-material paranasal sinus phantom for endoscopy training ii) a multi-material skull base simulator and iii) 3D patient-specific mandible templates. Digital processing of these phantoms is based on real patient or cadaveric 3D images such as CT or MRI data. Three endoscopic sinus surgeons examined the realism of the endoscopist training phantom. One experienced endoscopic skull base surgeon conducted advanced sinus procedures on the high-fidelity multi-material skull base simulator. Ten patients participated in a prospective clinical study examining patient-specific modeling for mandibular reconstructive surgery. Qualitative feedback to assess the realism of the endoscopy training phantom and high-fidelity multi-material phantom was acquired. Conformance comparisons using assessments from the blinded reconstructive surgeons measured the geometric performance between intra-operative and pre-operative reconstruction mandible plates. Both the endoscopy training phantom and the high-fidelity multi-material phantom received positive feedback on the realistic structure of the phantom models. Results suggested further improvement on the soft tissue structure of the phantom models is necessary. In the patient-specific mandible template study, the pre-operative plates were judged by two blinded surgeons as providing optimal conformance in 7 out of 10 cases. No statistical differences were found in plate fabrication time and conformance, with pre-operative plating providing the advantage of reducing time spent in the operation room. The applicability of common model design and fabrication techniques across a variety of otolaryngological sub-specialties suggests an emerging role for rapid prototyping technology in surgical education, procedure simulation, and clinical practice.

3D Rapid Prototyping for Otolaryngology—Head and Neck Surgery: Applications in Image-Guidance, Surgical Simulation and Patient-Specific Modeling

PubMed Central

Chan, Harley H. L.; Siewerdsen, Jeffrey H.; Vescan, Allan; Daly, Michael J.; Prisman, Eitan; Irish, Jonathan C.

2015-01-01

The aim of this study was to demonstrate the role of advanced fabrication technology across a broad spectrum of head and neck surgical procedures, including applications in endoscopic sinus surgery, skull base surgery, and maxillofacial reconstruction. The initial case studies demonstrated three applications of rapid prototyping technology are in head and neck surgery: i) a mono-material paranasal sinus phantom for endoscopy training ii) a multi-material skull base simulator and iii) 3D patient-specific mandible templates. Digital processing of these phantoms is based on real patient or cadaveric 3D images such as CT or MRI data. Three endoscopic sinus surgeons examined the realism of the endoscopist training phantom. One experienced endoscopic skull base surgeon conducted advanced sinus procedures on the high-fidelity multi-material skull base simulator. Ten patients participated in a prospective clinical study examining patient-specific modeling for mandibular reconstructive surgery. Qualitative feedback to assess the realism of the endoscopy training phantom and high-fidelity multi-material phantom was acquired. Conformance comparisons using assessments from the blinded reconstructive surgeons measured the geometric performance between intra-operative and pre-operative reconstruction mandible plates. Both the endoscopy training phantom and the high-fidelity multi-material phantom received positive feedback on the realistic structure of the phantom models. Results suggested further improvement on the soft tissue structure of the phantom models is necessary. In the patient-specific mandible template study, the pre-operative plates were judged by two blinded surgeons as providing optimal conformance in 7 out of 10 cases. No statistical differences were found in plate fabrication time and conformance, with pre-operative plating providing the advantage of reducing time spent in the operation room. The applicability of common model design and fabrication techniques across a variety of otolaryngological sub-specialties suggests an emerging role for rapid prototyping technology in surgical education, procedure simulation, and clinical practice. PMID:26331717

Fabrication of anatomically tapered foveal pits for retinal phantoms for optical coherence tomography

NASA Astrophysics Data System (ADS)

Lee, Gary C. F.; Smith, Gennifer T.; Agrawal, Monica; Ellerbee, Audrey K.

2015-03-01

Optical Coherence Tomography (OCT) has become a standard tool for diagnosing retinal disease in many ophthalmology clinics. Nonetheless, the technical and clinical research communities still lack a standardized phantom that could aid in evaluating and normalizing the various scan protocols and OCT machines employed at different institutions. Existing retinal phantoms designed for OCT imaging mimic some important features of the retina, such as the thickness and scattering properties of its many layers. However, the morphology of the foveal pit and the visible tapering of the retinal layers underlying the surface surrounding the pit remains a challenge to replicate in current phantoms. Recent attempts at creating a realistic foveal pit include molding, ablation and laser etching but have not proved sufficient to replicate this particular anatomical feature. In this work, we demonstrate a new fabrication procedure that is capable of replicating the tapered appearance of the retinal layers near the foveal pit using a combination of spin-coating and replica molding. The ability to create an anatomically correct foveal pit will allow for a new phantom better suited for intra- and inter-system evaluation and for improved testing of retinal segmentation algorithms.

New eye phantom for ophthalmic surgery

NASA Astrophysics Data System (ADS)

Fogli, Gessica; Orsi, Gianni; De Maria, Carmelo; Montemurro, Francesca; Palla, Michele; Rizzo, Stanislao; Vozzi, Giovanni

2014-06-01

In this work, we designed and realized a new phantom able to mimic the principal mechanical, rheological, and physical cues of the human eye and that can be used as a common benchmark to validate new surgical procedures, innovative vitrectomes, and as a training system for surgeons. This phantom, in particular its synthetic humor vitreous, had the aim of reproducing diffusion properties of the natural eye and can be used as a system to evaluate the pharmacokinetics of drugs and optimization of their dose, limiting animal experiments. The eye phantom was built layer-by-layer starting from the sclera up to the retina, using low cost and easy to process polymers. The validation of the phantom was carried out by mechanical characterization of each layer, by diffusion test with commercial drugs into a purposely developed apparatus, and finally by a team of ophthalmic surgeons. Experiments demonstrated that polycaprolactone, polydimethylsiloxane, and gelatin, properly prepared, are the best materials to mimic the mechanical properties of sclera, choroid, and retina, respectively. A polyvinyl alcohol-gelatin polymeric system is the best for mimicking the viscosity of the human humor vitreous, even if the bevacizumab half-life is lower than in the human eye.

A new, open-source, multi-modality digital breast phantom

NASA Astrophysics Data System (ADS)

Graff, Christian G.

2016-03-01

An anthropomorphic digital breast phantom has been developed with the goal of generating random voxelized breast models that capture the anatomic variability observed in vivo. This is a new phantom and is not based on existing digital breast phantoms or segmentation of patient images. It has been designed at the outset to be modality agnostic (i.e., suitable for use in modeling x-ray based imaging systems, magnetic resonance imaging, and potentially other imaging systems) and open source so that users may freely modify the phantom to suit a particular study. In this work we describe the modeling techniques that have been developed, the capabilities and novel features of this phantom, and study simulated images produced from it. Starting from a base quadric, a series of deformations are performed to create a breast with a particular volume and shape. Initial glandular compartments are generated using a Voronoi technique and a ductal tree structure with terminal duct lobular units is grown from the nipple into each compartment. An additional step involving the creation of fat and glandular lobules using a Perlin noise function is performed to create more realistic glandular/fat tissue interfaces and generate a Cooper's ligament network. A vascular tree is grown from the chest muscle into the breast tissue. Breast compression is performed using a neo-Hookean elasticity model. We show simulated mammographic and T1-weighted MRI images and study properties of these images.

High resolution, MRI-based, segmented, computerized head phantom

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zubal, I.G.; Harrell, C.R.; Smith, E.O.

1999-01-01

The authors have created a high-resolution software phantom of the human brain which is applicable to voxel-based radiation transport calculations yielding nuclear medicine simulated images and/or internal dose estimates. A software head phantom was created from 124 transverse MRI images of a healthy normal individual. The transverse T2 slices, recorded in a 256x256 matrix from a GE Signa 2 scanner, have isotropic voxel dimensions of 1.5 mm and were manually segmented by the clinical staff. Each voxel of the phantom contains one of 62 index numbers designating anatomical, neurological, and taxonomical structures. The result is stored as a 256x256x128 bytemore » array. Internal volumes compare favorably to those described in the ICRP Reference Man. The computerized array represents a high resolution model of a typical human brain and serves as a voxel-based anthropomorphic head phantom suitable for computer-based modeling and simulation calculations. It offers an improved realism over previous mathematically described software brain phantoms, and creates a reference standard for comparing results of newly emerging voxel-based computations. Such voxel-based computations lead the way to developing diagnostic and dosimetry calculations which can utilize patient-specific diagnostic images. However, such individualized approaches lack fast, automatic segmentation schemes for routine use; therefore, the high resolution, typical head geometry gives the most realistic patient model currently available.« less

Soft 3D-Printed Phantom of the Human Kidney with Collecting System.

PubMed

Adams, Fabian; Qiu, Tian; Mark, Andrew; Fritz, Benjamin; Kramer, Lena; Schlager, Daniel; Wetterauer, Ulrich; Miernik, Arkadiusz; Fischer, Peer

2017-04-01

Organ models are used for planning and simulation of operations, developing new surgical instruments, and training purposes. There is a substantial demand for in vitro organ phantoms, especially in urological surgery. Animal models and existing simulator systems poorly mimic the detailed morphology and the physical properties of human organs. In this paper, we report a novel fabrication process to make a human kidney phantom with realistic anatomical structures and physical properties. The detailed anatomical structure was directly acquired from high resolution CT data sets of human cadaveric kidneys. The soft phantoms were constructed using a novel technique that combines 3D wax printing and polymer molding. Anatomical details and material properties of the phantoms were validated in detail by CT scan, ultrasound, and endoscopy. CT reconstruction, ultrasound examination, and endoscopy showed that the designed phantom mimics a real kidney's detailed anatomy and correctly corresponds to the targeted human cadaver's upper urinary tract. Soft materials with a tensile modulus of 0.8-1.5 MPa as well as biocompatible hydrogels were used to mimic human kidney tissues. We developed a method of constructing 3D organ models from medical imaging data using a 3D wax printing and molding process. This method is cost-effective means for obtaining a reproducible and robust model suitable for surgical simulation and training purposes.

Aeroacoustic Measurements of a Wing/Slat Model

NASA Astrophysics Data System (ADS)

Mendoza, Jeff M.; Brooks, Thomas F.; Humphreys, William M.

2002-01-01

Aeroacoustic evaluations of high-lift devices have been carried out in the Quiet Flow Facility of the NASA Langley Research Center. The present paper deals with detailed flow and acoustic measurements that have been made to understand, and to possibly predict and reduce, the noise from a wing leading edge slat configuration. The acoustic database is obtained by a moveable Small Aperture Directional Array (SADA) of microphones designed to electronically steer to different portions of models under study. The slat is shown to be a uniform distributed noise source. The data was processed such that spectra and directivity were determined with respect to a one-foot span of slat. The spectra are normalized in various fashions to demonstrate slat noise character. In order to equate portions of the spectra to different slat noise components, trailing edge noise predictions using measured slat boundary layer parameters as inputs are compared to the measured slat noise spectra.

A cargo inspection system based on pulsed fast neutron analysis (PFNA).

PubMed

Ipe, N E; Olsher, R; Ryge, P; Mrozack, J; Thieu, J

2005-01-01

A cargo inspection system based on pulsed fast neutron analysis (PFNA) is to be used at a border crossing to detect explosives and contraband hidden in trucks and cargo containers. Neutrons are produced by the interaction of deuterons in a deuterium target mounted on a moveable scan arm. The collimated pulsed fast neutron beam is used to determine the location and composition of objects in a cargo container. The neutrons produce secondary gamma rays that are characteristic of the object's elemental composition. The cargo inspection system building consists of an accelerator room and an inspection tunnel. The accelerator room is shielded and houses the injector, accelerator and the neutron production gas target. The inspection tunnel is partially shielded. The truck or container to be inspected will be moved through the inspection tunnel by a conveyor system. The facility and radiation source terms considered in the shielding design are described.

Mass analysis of neutral particles and ions released during electrical breakdowns on spacecraft surfaces

NASA Technical Reports Server (NTRS)

Kendall, B. R. F.

1983-01-01

A specialized spectrometer was designed and developed to measure the mass and velocity distributions of neutral particles (molecules and molecular clusters) released from metal-backed Teflon and Kapton films. Promising results were obtained with an insulation breakdown initiation system based on a moveable contact touching the insulated surfaces. A variable energy, high voltage pulse is applied to the contact. The resulting surface damage sites can be made similar in size and shape to those produced by a high voltage electron beam system operating at similar discharge energies. The point discharge apparatus was used for final development of several high speed recording systems and for measurements of the composition of the materials given off by the discharge. Results with this apparatus show evolution of large amounts of fluorocarbon fragments from discharge through Teflon FEP, while discharges through Kapton produce mainly very light hydrocarbon fragments at masses below about 80 a.m.u.

KSC-07pd0689

NASA Image and Video Library

2007-03-15

VANDENBERG AIR FORCE BASE, CALIF. -- In Building 1555 at North Vandenberg Air Force Base, workers lower the AIM spacecraft onto a moveable base. AIM will be moved into an area where a partial deployment of the solar arrays on the spacecraft will take place.The AIM spacecraft will fly three instruments designed to study polar mesospheric clouds located at the edge of space, 50 miles above the Earth's surface in the coldest part of the planet's atmosphere. The mission's primary goal is to explain why these clouds form and what has caused them to become brighter and more numerous and appear at lower latitudes in recent years. AIM's results will provide the basis for the study of long-term variability in the mesospheric climate and its relationship to global climate change. AIM is scheduled to be mated to the Pegasus XL during the second week of April, after which final inspections will be conducted. Launch is scheduled for April 25.

Orbital Sciences Pegasus XL AIM Processing

NASA Image and Video Library

2007-03-16

In Building 1555 at North Vandenberg Air Force Base, workers lower the AIM spacecraft onto a moveable base. AIM will be moved into an area where a partial deployment of the solar arrays on the spacecraft will take place.The AIM spacecraft will fly three instruments designed to study polar mesospheric clouds located at the edge of space, 50 miles above the Earth's surface in the coldest part of the planet's atmosphere. The mission's primary goal is to explain why these clouds form and what has caused them to become brighter and more numerous and appear at lower latitudes in recent years. AIM's results will provide the basis for the study of long-term variability in the mesospheric climate and its relationship to global climate change. AIM is scheduled to be mated to the Pegasus XL during the second week of April, after which final inspections will be conducted. Launch is scheduled for April 25.

Injuries on British climbing walls.

PubMed Central

Limb, D

1995-01-01

A postal survey was carried out of the 90 most accessible climbing walls in England, Scotland and Wales to determine the incidence and nature of injuries requiring emergency treatment associated with their use. Over a two year period, representing 1.021 million visits to the 56 walls used by more than 30 climbers per week, 55 significant injuries were recorded. The rate of injury was not related to any identified design or safety feature of the walls, although upper limb injuries were proportionally more common in walls which provided thinner fixed landing mats rather than thicker, moveable crash mats. The overall rate of injury was very low and climbers seem to modify risk taking behaviour and thus compensate for the level of safety equipment available. It may be possible to reduce the injury rate further by providing seamless ground cover with matting of adequate energy absorbency. Images Figure 1 PMID:8800849

Wind tunnel balance system for determination of wind-induced vibrations of a rigid shuttle model in the launch configuration

NASA Technical Reports Server (NTRS)

1971-01-01

A wind tunnel balance system was designed to determine the wind-induced vibrations of a space shuttle model. The balance utilizes a flexible sting mounting in conjunction with a geometrically scaled rigid model. Bending and torsional displacements are determined through strain-gauge-instrumented spring bar mechanisms. The natural frequency of the string-model system can be varied continuously throughout the expected scaled frequency range of the shuttle vehicle while a test is in progress by the use of moveable riders on the spring bar mechanism. Through the use of a frequency analyzer, the output can be used to determine troublesome vibrational frequencies. A dimensional analysis of the wind-induced vibration problem is also presented which suggests a test procedure. In addition a computer program for analytical studies of the forced vibration problem is presented.

Adaptive Rules In Emergent Logistics (ARIEL) An Agent-Based Analysis Environment to Study Adaptive Route-Finding Constantly Changing Road-Networks

DTIC Science & Technology

2003-06-01

my wife Karin, my daughter Jasmin and my son Jan for their support and huge patience. Without the security and support of a loving home, none of...contains the trucks, which are the only moveable objects in the system. In essence they provide functionality and cannot act themselves. The layer

Recirculating electric air filter

DOEpatents

Bergman, Werner

1986-01-01

An electric air filter cartridge has a cylindrical inner high voltage eleode, a layer of filter material, and an outer ground electrode formed of a plurality of segments moveably connected together. The outer electrode can be easily opened to remove or insert filter material. Air flows through the two electrodes and the filter material and is exhausted from the center of the inner electrode.

29 CFR 570.65 - Occupations involving the operation of circular saws, band saws, guillotine shears, chain saws...

Code of Federal Regulations, 2013 CFR

2013-07-01

... notches or teeth, running over wheels or pulleys, and used for sawing materials. Chain saw shall mean a... machine equipped with a moveable blade operated vertically and used to shear materials. The term shall not... moving blade that alternately changes direction on a linear cutting axis used for sawing materials. Wood...

29 CFR 570.65 - Occupations involving the operation of circular saws, band saws, guillotine shears, chain saws...

Code of Federal Regulations, 2012 CFR

2012-07-01

... notches or teeth, running over wheels or pulleys, and used for sawing materials. Chain saw shall mean a... machine equipped with a moveable blade operated vertically and used to shear materials. The term shall not... moving blade that alternately changes direction on a linear cutting axis used for sawing materials. Wood...

29 CFR 570.65 - Occupations involved in the operations of circular saws, band saws, guillotine shears, chain saws...

Code of Federal Regulations, 2011 CFR

2011-07-01

... notches or teeth, running over wheels or pulleys, and used for sawing materials. Chain saw shall mean a... machine equipped with a moveable blade operated vertically and used to shear materials. The term shall not... moving blade that alternately changes direction on a linear cutting axis used for sawing materials. Wood...

29 CFR 570.65 - Occupations involving the operation of circular saws, band saws, guillotine shears, chain saws...

Code of Federal Regulations, 2014 CFR

2014-07-01

... notches or teeth, running over wheels or pulleys, and used for sawing materials. Chain saw shall mean a... machine equipped with a moveable blade operated vertically and used to shear materials. The term shall not... moving blade that alternately changes direction on a linear cutting axis used for sawing materials. Wood...

49 CFR 213.353 - Turnouts, crossovers, and lift rail assemblies or other transition devices on moveable bridges.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 49 Transportation 4 2011-10-01 2011-10-01 false Turnouts, crossovers, and lift rail assemblies or... SAFETY STANDARDS Train Operations at Track Classes 6 and Higher § 213.353 Turnouts, crossovers, and lift... shall be at least 11/2 inches wide. (d) For all turnouts and crossovers, and lift rail assemblies or...

49 CFR 213.353 - Turnouts, crossovers, and lift rail assemblies or other transition devices on moveable bridges.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 4 2010-10-01 2010-10-01 false Turnouts, crossovers, and lift rail assemblies or... SAFETY STANDARDS Train Operations at Track Classes 6 and Higher § 213.353 Turnouts, crossovers, and lift... shall be at least 11/2 inches wide. (d) For all turnouts and crossovers, and lift rail assemblies or...

TARDEC Overview: Ground Vehicle Power and Mobility

DTIC Science & Technology

2011-02-04

Fuel & Water Distribution • Force Sustainment • Construction Equipment • Bridging • Assured Mobility Systems Robotics • TALON • PackBot • MARCbot...Equipment • Mechanical Countermine Equipment • Tactical Bridging Intelligent Ground Systems • Autonomous Robotics Systems • Safe Operations...Test Cell • Hybrid Electric Reconfigurable Moveable Integration Testbed (HERMIT) • Electro-chemical Analysis and Research Lab (EARL) • Battery Lab • Air

Recirculating electric air filter

DOEpatents

Bergman, W.

1985-01-09

An electric air filter cartridge has a cylindrical inner high voltage electrode, a layer of filter material, and an outer ground electrode formed of a plurality of segments moveably connected together. The outer electrode can be easily opened to remove or insert filter material. Air flows through the two electrodes and the filter material and is exhausted from the center of the inner electrode.

Au@Y 2O 3:Eu 3+ rare earth oxide hollow sub-microspheres with encapsulated gold nanoparticles and their optical properties

NASA Astrophysics Data System (ADS)

Min, Yu-Lin; Wan, Yong; Yu, Shu-Hong

2009-01-01

A facile method to synthesize novel Au@Y 2O 3:Eu 3+ hollow sub-microspheres encapsulated with moveable gold nanoparticle core and Y 2O 3:Eu 3+ as shell via two-step coating processes and a succeeding calcination process has been developed. Silica coating on citrate-stabilized gold nanoparticles with a size of 25 nm can be obtained through a slightly modified Stöber process. Gold particles coated with double shell silica and Eu doped Y(OH) 3 can be obtained by coating on the Au@SiO 2 spheres through simply adding Y(NO 3) 3, Eu(NO 3) 3 and an appropriate quantity of NH 3·H 2O. Au@Y 2O 3:Eu 3+ hollow sub-microspheres with moveable individual Au nanoparticle as core can be obtained after calcination of Au@Y 2O 3:Eu 3+ particles at 600 °C for 2 h. These new core-shell structures with encapsulated gold nanoparticles have combined optical properties of both the Au nanoparticles and the Y 2O 3:Eu 3+ phosphor materials which might have potential applications.

Characterization of a high-energy in-line phase contrast tomosynthesis prototype

PubMed Central

Wu, Di; Yan, Aimin; Li, Yuhua; Wong, Molly D.; Zheng, Bin; Wu, Xizeng; Liu, Hong

2015-01-01

Purpose: In this research, a high-energy in-line phase contrast tomosynthesis prototype was developed and characterized through quantitative investigations and phantom studies. Methods: The prototype system consists of an x-ray source, a motorized rotation stage, and a CMOS detector with a pixel pitch of 0.05 mm. The x-ray source was operated at 120 kVp for this study, and the objects were mounted on the rotation stage 76.2 cm (R1) from the source and 114.3 cm (R2) from the detector. The large air gap between the object and detector guarantees sufficient phase-shift effects. The quantitative evaluation of this prototype included modulation transfer function and noise power spectrum measurements conducted under both projection mode and tomosynthesis mode. Phantom studies were performed including three custom designed phantoms with complex structures: a five-layer bubble wrap phantom, a fishbone phantom, and a chicken breast phantom with embedded fibrils and mass structures extracted from an ACR phantom. In-plane images of the phantoms were acquired to investigate their image qualities through observation, intensity profile plots, edge enhancement evaluations, and/or contrast-to-noise ratio calculations. In addition, the robust phase-attenuation duality (PAD)-based phase retrieval method was applied to tomosynthesis for the first time in this research. It was utilized as a preprocessing method to fully exhibit phase contrast on the angular projection before reconstruction. Results: The resolution and noise characteristics of this high-energy in-line phase contrast tomosynthesis prototype were successfully investigated and demonstrated. The phantom studies demonstrated that this imaging prototype can successfully remove the structure overlapping in phantom projections, obtain delineate interfaces, and achieve better contrast-to-noise ratio after applying phase retrieval to the angular projections. Conclusions: This research successfully demonstrated a high-energy in-line phase contrast tomosynthesis prototype. In addition, the PAD-based method of phase retrieval was combined with tomosynthesis imaging for the first time, which demonstrated its capability in significantly improving the contrast-to-noise ratios in the images. PMID:25979035

Technical Note: Construction of heterogeneous head phantom for quality control in stereotactic radiosurgery.

PubMed

Najafi, Mohsen; Teimouri, Javad; Shirazi, Alireza; Geraily, Ghazale; Esfahani, Mahbod; Shafaei, Mostafa

2017-10-01

Stereotactic radiosurgery is a high precision modality for conformally delivering high doses of radiation to the brain lesion with a large dose volume. Several studies for the quality control of this technique were performed to measure the dose delivered to the target with a homogenous head phantom and some dosimeters. Some studies were also performed with one or two instances of heterogeneity in the head phantom to measure the dose delivered to the target. But these studies assumed the head as a sphere and simple shape heterogeneity. The construction of an adult human head phantom with the same size, shape, and real inhomogeneity as an adult human head is needed. Only then is measuring the accurate dose delivered to the area of interest and comparison with the calculated dose possible. According to the ICRU Report 44, polytetrafluoroethylene (PTFE) and methyl methacrylate were selected as a bone and soft tissue, respectively. A set of computed tomography (CT) scans from a standard human head were taken, and simplification of the CT images was used to design the layers of the phantom. The parts of each slice were cut and attached together. Tests of density and CT number were done to compare the material of the phantom with tissues of the head. The dose delivered to the target was measured with an EBT3 film. The density of the PTFE and Plexiglas that were inserted in the phantom are in good agreement with bone and soft tissue. Also, the CT numbers of these materials have a low difference. The dose distribution from the EBT3 film and the treatment planning system is similar. The constructed phantom with a size and inhomogeneity like an adult human head is suitable to measure the dose delivered to the area of interest. It also helps make an accurate comparison with the calculated dose by the treatment planning system. By using this phantom, the actual dose delivered to the target was obtained. This anthropomorphic head phantom can be used in other modalities of radiosurgery as well. © 2017 American Association of Physicists in Medicine.

Multimodal, 3D pathology-mimicking bladder phantom for evaluation of cystoscopic technologies (Conference Presentation)

NASA Astrophysics Data System (ADS)

Smith, Gennifer T.; Lurie, Kristen L.; Zlatev, Dimitar V.; Liao, Joseph C.; Ellerbee, Audrey K.

2016-02-01

Optical coherence tomography (OCT) and blue light cystoscopy (BLC) have shown significant potential as complementary technologies to traditional white light cystoscopy (WLC) for early bladder cancer detection. Three-dimensional (3D) organ-mimicking phantoms provide realistic imaging environments for testing new technology designs, the diagnostic potential of systems, and novel image processing algorithms prior to validation in real tissue. Importantly, the phantom should mimic features of healthy and diseased tissue as they appear under WLC, BLC, and OCT, which are sensitive to tissue color and structure, fluorescent contrast, and optical scattering of subsurface layers, respectively. We present a phantom posing the hollow shape of the bladder and fabricated using a combination of 3D-printing and spray-coating with Dragon Skin (DS) (Smooth-On Inc.), a highly elastic polymer to mimic the layered structure of the bladder. Optical scattering of DS was tuned by addition of titanium dioxide, resulting in scattering coefficients sufficient to cover the human bladder range (0.49 to 2.0 mm^-1). Mucosal vasculature and tissue coloration were mimicked with elastic cord and red dye, respectively. Urethral access was provided through a small hole excised from the base of the phantom. Inserted features of bladder pathology included altered tissue color (WLC), fluorescence emission (BLC), and variations in layered structure (OCT). The phantom surface and underlying material were assessed on the basis of elasticity, optical scattering, layer thicknesses, and qualitative image appearance. WLC, BLC, and OCT images of normal and cancerous features in the phantom qualitatively matched corresponding images from human bladders.

Poster - Thurs Eve-43: Verification of dose calculation with tissue inhomogeneity using MapCHECK.

PubMed

Korol, R; Chen, J; Mosalaei, H; Karnas, S

2008-07-01

MapCHECK (Sun Nuclear, Melbourne, FL) with 445 diode detectors has been used widely for routine IMRT quality assurance (QA) 1 . However, routine IMRT QA has not included the verification of inhomogeneity effects. The objective of this study is to use MapCHECK and a phantom to verify dose calculation and IMRT delivery with tissue inhomogeneity. A phantom with tissue inhomogeneities was placed on top of MapCHECK to measure the planar dose for an anterior beam with photon energy 6 MV or 18 MV. The phantom was composed of a 3.5 cm thick block of lung equivalent material and solid water arranged side by side with a 0.5 cm slab of solid water on the top of the phantom. The phantom setup including MapCHECK was CT scanned and imported into Pinnacle 8.0d for dose calculation. Absolute dose distributions were compared with gamma criteria 3% for dose difference and 3 mm for distance-to-agreement. The results are in good agreement between the measured and calculated planar dose with 88% pass rate based on the gamma analysis. The major dose difference was at the lung-water interface. Further investigation will be performed on a custom designed inhomogeneity phantom with inserts of varying densities and effective depth to create various dose gradients at the interface for dose calculation and delivery verification. In conclusion, a phantom with tissue inhomogeneities can be used with MapCHECK for verification of dose calculation and delivery with tissue inhomogeneity. © 2008 American Association of Physicists in Medicine.

Comprehensive quality assurance phantom for the small animal radiation research platform (SARRP)

PubMed Central

Jermoumi, M.; Korideck, H.; Bhagwat, M.; Zygmanski, P.; Makrigiogos, G.M.; Berbeco, R.I.; Cormack, R.C.; Ngwa, W.

2016-01-01

Purpose To develop and test the suitability and performance of a comprehensive quality assurance (QA) phantom for the Small Animal Radiation Research Platform (SARRP). Methods and materials A QA phantom was developed for carrying out daily, monthly and annual QA tasks including: imaging, dosimetry and treatment planning system (TPS) performance evaluation of the SARRP. The QA phantom consists of 15 (60 × 60 × 5 mm3) kV-energy tissue equivalent solid water slabs. The phantom can incorporate optically stimulated luminescence dosimeters (OSLD), Mosfet or film. One slab, with inserts and another slab with hole patterns are particularly designed for image QA. Results Output constancy measurement results showed daily variations within 3%. Using the Mosfet in phantom as target, results showed that the difference between TPS calculations and measurements was within 5%. Annual QA results for the Percentage depth dose (PDD) curves, lateral beam profiles, beam flatness and beam profile symmetry were found consistent with results obtained at commissioning. PDD curves obtained using film and OSLDs showed good agreement. Image QA was performed monthly, with image-quality parameters assessed in terms of CBCT image geometric accuracy, CT number accuracy, image spatial resolution, noise and image uniformity. Conclusions The results show that the developed QA phantom can be employed as a tool for comprehensive performance evaluation of the SARRP. The study provides a useful reference for development of a comprehensive quality assurance program for the SARRP and other similar small animal irradiators, with proposed tolerances and frequency of required tests. PMID:25964129

Comprehensive quality assurance phantom for the small animal radiation research platform (SARRP).

PubMed

Jermoumi, M; Korideck, H; Bhagwat, M; Zygmanski, P; Makrigiogos, G M; Berbeco, R I; Cormack, R C; Ngwa, W

2015-07-01

To develop and test the suitability and performance of a comprehensive quality assurance (QA) phantom for the Small Animal Radiation Research Platform (SARRP). A QA phantom was developed for carrying out daily, monthly and annual QA tasks including: imaging, dosimetry and treatment planning system (TPS) performance evaluation of the SARRP. The QA phantom consists of 15 (60 × 60 × 5 mm(3)) kV-energy tissue equivalent solid water slabs. The phantom can incorporate optically stimulated luminescence dosimeters (OSLD), Mosfet or film. One slab, with inserts and another slab with hole patterns are particularly designed for image QA. Output constancy measurement results showed daily variations within 3%. Using the Mosfet in phantom as target, results showed that the difference between TPS calculations and measurements was within 5%. Annual QA results for the Percentage depth dose (PDD) curves, lateral beam profiles, beam flatness and beam profile symmetry were found consistent with results obtained at commissioning. PDD curves obtained using film and OSLDs showed good agreement. Image QA was performed monthly, with image-quality parameters assessed in terms of CBCT image geometric accuracy, CT number accuracy, image spatial resolution, noise and image uniformity. The results show that the developed QA phantom can be employed as a tool for comprehensive performance evaluation of the SARRP. The study provides a useful reference for development of a comprehensive quality assurance program for the SARRP and other similar small animal irradiators, with proposed tolerances and frequency of required tests. Copyright © 2015 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Effectiveness of mirror therapy, motor imagery, and virtual feedback on phantom limb pain following amputation: A systematic review.

PubMed

Herrador Colmenero, Laura; Perez Marmol, Jose Manuel; Martí-García, Celia; Querol Zaldivar, María de Los Ángeles; Tapia Haro, Rosa María; Castro Sánchez, Adelaida María; Aguilar-Ferrándiz, María Encarnación

2018-06-01

Phantom limb pain is reported in 50%-85% of people with amputation. Clinical interventions in treating central pain, such as mirror therapy, motor imagery, or virtual visual feedback, could redound in benefits to amputee patients with phantom limb pain. To provide an overview of the effectiveness of different techniques for treating phantom limb pain in amputee patients. Systematic review. A computerized literature search up to April 2017 was performed using the following databases: PubMed, Scopus, CINAHL, MEDLINE, ProQuest, PEDro, EBSCOhost, and Cochrane Plus. Methodological quality and internal validity score of each study were assessed using PEDro scale. For data synthesis, qualitative methods from the Cochrane Back Review Group were applied. In all, 12 studies met our inclusion criteria, where 9 were rated as low methodological quality and 3 rated moderate quality. All studies showed a significant reduction in pain, but there was heterogeneity among subjects and methodologies and any high-quality clinical trial (PEDro score ≤8; internal validity score ≤5) was not found. Mirror therapy, motor imaginary, and virtual visual feedback reduce phantom limb pain; however, there is limited scientific evidence supporting their effectiveness. Future studies should include designs with more solid research methods, exploring short- and long-term benefits of these therapies. Clinical relevance This systematic review investigates the effectiveness of mirror therapy, motor imagery, and virtual visual feedback on phantom limb pain, summarizing the currently published trials and evaluating the research quality. Although these interventions have positive benefits in phantom limb pain, there is still a lack of evidence for supporting their effectiveness.

Assessment of Spectral Doppler in Preclinical Ultrasound Using a Small-Size Rotating Phantom

PubMed Central

Yang, Xin; Sun, Chao; Anderson, Tom; Moran, Carmel M.; Hadoke, Patrick W.F.; Gray, Gillian A.; Hoskins, Peter R.

2013-01-01

Preclinical ultrasound scanners are used to measure blood flow in small animals, but the potential errors in blood velocity measurements have not been quantified. This investigation rectifies this omission through the design and use of phantoms and evaluation of measurement errors for a preclinical ultrasound system (Vevo 770, Visualsonics, Toronto, ON, Canada). A ray model of geometric spectral broadening was used to predict velocity errors. A small-scale rotating phantom, made from tissue-mimicking material, was developed. True and Doppler-measured maximum velocities of the moving targets were compared over a range of angles from 10° to 80°. Results indicate that the maximum velocity was overestimated by up to 158% by spectral Doppler. There was good agreement (<10%) between theoretical velocity errors and measured errors for beam-target angles of 50°–80°. However, for angles of 10°–40°, the agreement was not as good (>50%). The phantom is capable of validating the performance of blood velocity measurement in preclinical ultrasound. PMID:23711503

MCAT to XCAT: The Evolution of 4-D Computerized Phantoms for Imaging Research

PubMed Central

Paul Segars, W.; Tsui, Benjamin M. W.

2012-01-01

Recent work in the development of computerized phantoms has focused on the creation of ideal “hybrid” models that seek to combine the realism of a patient-based voxelized phantom with the flexibility of a mathematical or stylized phantom. We have been leading the development of such computerized phantoms for use in medical imaging research. This paper will summarize our developments dating from the original four-dimensional (4-D) Mathematical Cardiac-Torso (MCAT) phantom, a stylized model based on geometric primitives, to the current 4-D extended Cardiac-Torso (XCAT) and Mouse Whole-Body (MOBY) phantoms, hybrid models of the human and laboratory mouse based on state-of-the-art computer graphics techniques. This paper illustrates the evolution of computerized phantoms toward more accurate models of anatomy and physiology. This evolution was catalyzed through the introduction of nonuniform rational b-spline (NURBS) and subdivision (SD) surfaces, tools widely used in computer graphics, as modeling primitives to define a more ideal hybrid phantom. With NURBS and SD surfaces as a basis, we progressed from a simple geometrically based model of the male torso (MCAT) containing only a handful of structures to detailed, whole-body models of the male and female (XCAT) anatomies (at different ages from newborn to adult), each containing more than 9000 structures. The techniques we applied for modeling the human body were similarly used in the creation of the 4-D MOBY phantom, a whole-body model for the mouse designed for small animal imaging research. From our work, we have found the NURBS and SD surface modeling techniques to be an efficient and flexible way to describe the anatomy and physiology for realistic phantoms. Based on imaging data, the surfaces can accurately model the complex organs and structures in the body, providing a level of realism comparable to that of a voxelized phantom. In addition, they are very flexible. Like stylized models, they can easily be manipulated to model anatomical variations and patient motion. With the vast improvement in realism, the phantoms developed in our lab can be combined with accurate models of the imaging process (SPECT, PET, CT, magnetic resonance imaging, and ultrasound) to generate simulated imaging data close to that from actual human or animal subjects. As such, they can provide vital tools to generate predictive imaging data from many different subjects under various scanning parameters from which to quantitatively evaluate and improve imaging devices and techniques. From the MCAT to XCAT, we will demonstrate how NURBS and SD surface modeling have resulted in a major evolutionary advance in the development of computerized phantoms for imaging research. PMID:26472880

MCAT to XCAT: The Evolution of 4-D Computerized Phantoms for Imaging Research: Computer models that take account of body movements promise to provide evaluation and improvement of medical imaging devices and technology.

PubMed

Paul Segars, W; Tsui, Benjamin M W

2009-12-01

Recent work in the development of computerized phantoms has focused on the creation of ideal "hybrid" models that seek to combine the realism of a patient-based voxelized phantom with the flexibility of a mathematical or stylized phantom. We have been leading the development of such computerized phantoms for use in medical imaging research. This paper will summarize our developments dating from the original four-dimensional (4-D) Mathematical Cardiac-Torso (MCAT) phantom, a stylized model based on geometric primitives, to the current 4-D extended Cardiac-Torso (XCAT) and Mouse Whole-Body (MOBY) phantoms, hybrid models of the human and laboratory mouse based on state-of-the-art computer graphics techniques. This paper illustrates the evolution of computerized phantoms toward more accurate models of anatomy and physiology. This evolution was catalyzed through the introduction of nonuniform rational b-spline (NURBS) and subdivision (SD) surfaces, tools widely used in computer graphics, as modeling primitives to define a more ideal hybrid phantom. With NURBS and SD surfaces as a basis, we progressed from a simple geometrically based model of the male torso (MCAT) containing only a handful of structures to detailed, whole-body models of the male and female (XCAT) anatomies (at different ages from newborn to adult), each containing more than 9000 structures. The techniques we applied for modeling the human body were similarly used in the creation of the 4-D MOBY phantom, a whole-body model for the mouse designed for small animal imaging research. From our work, we have found the NURBS and SD surface modeling techniques to be an efficient and flexible way to describe the anatomy and physiology for realistic phantoms. Based on imaging data, the surfaces can accurately model the complex organs and structures in the body, providing a level of realism comparable to that of a voxelized phantom. In addition, they are very flexible. Like stylized models, they can easily be manipulated to model anatomical variations and patient motion. With the vast improvement in realism, the phantoms developed in our lab can be combined with accurate models of the imaging process (SPECT, PET, CT, magnetic resonance imaging, and ultrasound) to generate simulated imaging data close to that from actual human or animal subjects. As such, they can provide vital tools to generate predictive imaging data from many different subjects under various scanning parameters from which to quantitatively evaluate and improve imaging devices and techniques. From the MCAT to XCAT, we will demonstrate how NURBS and SD surface modeling have resulted in a major evolutionary advance in the development of computerized phantoms for imaging research.

Post-Mastectomy and Phantom Breast Pain: Risk Factors, Natural History, and Impact on Quality of Life

DTIC Science & Technology

1999-07-01

be significantly disabled by their chronic pain and can suffer from substantial reductions in quality of life . The primary aims of this research...and examine their impact on quality of life using a prospective research design. To date, 40 women scheduled for surgical procedures for breast cancer...with periodic assessments of pain, health-related quality of life , and psychosocial variables. This allows risk factors for PMPS and phantom breast

Calibration and evaluation of a magnetically tracked ICE probe for guidance of left atrial ablation therapy

NASA Astrophysics Data System (ADS)

Linte, Cristian A.; Rettmann, Maryam E.; Dilger, Ben; Gunawan, Mia S.; Arunachalam, Shivaram P.; Holmes, David R., III; Packer, Douglas L.; Robb, Richard A.

2012-02-01

The novel prototype system for advanced visualization for image-guided left atrial ablation therapy developed in our laboratory permits ready integration of multiple imaging modalities, surgical instrument tracking, interventional devices and electro-physiologic data. This technology allows subject-specific procedure planning and guidance using 3D dynamic, patient-specific models of the patient's heart, augmented with real-time intracardiac echocardiography (ICE). In order for the 2D ICE images to provide intuitive visualization for accurate catheter to surgical target navigation, the transducer must be tracked, so that the acquired images can be appropriately presented with respect to the patient-specific anatomy. Here we present the implementation of a previously developed ultrasound calibration technique for a magnetically tracked ICE transducer, along with a series of evaluation methods to ensure accurate imaging and faithful representation of the imaged structures. Using an engineering-designed phantom, target localization accuracy is assessed by comparing known target locations with their transformed locations inferred from the tracked US images. In addition, the 3D volume reconstruction accuracy is also estimated by comparing a truth volume to that reconstructed from sequential 2D US images. Clinically emulating validation studies are conducted using a patient-specific left atrial phantom. Target localization error of clinically-relevant surgical targets represented by nylon fiducials implanted within the endocardial wall of the phantom was assessed. Our studies have demonstrated 2.4 +/- 0.8 mm target localization error in the engineering-designed evaluation phantoms, 94.8 +/- 4.6 % volume reconstruction accuracy, and 3.1 +/- 1.2 mm target localization error in the left atrial-mimicking phantom. These results are consistent with those disseminated in the literature and also with the accuracy constraints imposed by the employed technology and the clinical application.

Precision measurements of the RSA method using a phantom model of hip prosthesis.

PubMed

Mäkinen, Tatu J; Koort, Jyri K; Mattila, Kimmo T; Aro, Hannu T

2004-04-01

Radiostereometric analysis (RSA) has become one of the recommended techniques for pre-market evaluation of new joint implant designs. In this study we evaluated the effect of repositioning of X-ray tubes and phantom model on the precision of the RSA method. In precision measurements, we utilized mean error of rigid body fitting (ME) values as an internal control for examinations. ME value characterizes relative motion among the markers within each rigid body and is conventionally used to detect loosening of a bone marker. Three experiments, each consisting of 10 double examinations, were performed. In the first experiment, the X-ray tubes and the phantom model were not repositioned between one double examination. In experiments two and three, the X-ray tubes were repositioned between one double examination. In addition, the position of the phantom model was changed in experiment three. Results showed that significant differences could be found in 2 of 12 comparisons when evaluating the translation and rotation of the prosthetic components. Repositioning procedures increased ME values mimicking deformation of rigid body segments. Thus, ME value seemed to be a more sensitive parameter than migration values in this study design. These results confirmed the importance of standardized radiographic technique and accurate patient positioning for RSA measurements. Standardization and calibration procedures should be performed with phantom models in order to avoid unnecessary radiation dose of the patients. The present model gives the means to establish and to follow the intra-laboratory precision of the RSA method. The model is easily applicable in any research unit and allows the comparison of the precision values in different laboratories of multi-center trials.

SU-C-213-04: Application of Depth Sensing and 3D-Printing Technique for Total Body Irradiation (TBI) Patient Measurement and Treatment Planning

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, M; Suh, T; Research Institute of Biomedical Engineering, College of Medicine, The Catholic University of Korea, Seoul

2015-06-15

Purpose: To develop and validate an innovative method of using depth sensing cameras and 3D printing techniques for Total Body Irradiation (TBI) treatment planning and compensator fabrication. Methods: A tablet with motion tracking cameras and integrated depth sensing was used to scan a RANDOTM phantom arranged in a TBI treatment booth to detect and store the 3D surface in a point cloud (PC) format. The accuracy of the detected surface was evaluated by comparison to extracted measurements from CT scan images. The thickness, source to surface distance and off-axis distance of the phantom at different body section was measured formore » TBI treatment planning. A 2D map containing a detailed compensator design was calculated to achieve uniform dose distribution throughout the phantom. The compensator was fabricated using a 3D printer, silicone molding and tungsten powder. In vivo dosimetry measurements were performed using optically stimulated luminescent detectors (OSLDs). Results: The whole scan of the anthropomorphic phantom took approximately 30 seconds. The mean error for thickness measurements at each section of phantom compare to CT was 0.44 ± 0.268 cm. These errors resulted in approximately 2% dose error calculation and 0.4 mm tungsten thickness deviation for the compensator design. The accuracy of 3D compensator printing was within 0.2 mm. In vivo measurements for an end-to-end test showed the overall dose difference was within 3%. Conclusion: Motion cameras and depth sensing techniques proved to be an accurate and efficient tool for TBI patient measurement and treatment planning. 3D printing technique improved the efficiency and accuracy of the compensator production and ensured a more accurate treatment delivery.« less

A method to acquire CT organ dose map using OSL dosimeters and ATOM anthropomorphic phantoms

PubMed Central

Zhang, Da; Li, Xinhua; Gao, Yiming; Xu, X. George; Liu, Bob

2013-01-01

Purpose: To present the design and procedure of an experimental method for acquiring densely sampled organ dose map for CT applications, based on optically stimulated luminescence (OSL) dosimeters “nanoDots” and standard ATOM anthropomorphic phantoms; and to provide the results of applying the method—a dose data set with good statistics for the comparison with Monte Carlo simulation result in the future. Methods: A standard ATOM phantom has densely located holes (in 3 × 3 cm or 1.5 × 1.5 cm grids), which are too small (5 mm in diameter) to host many types of dosimeters, including the nanoDots. The authors modified the conventional way in which nanoDots are used, by removing the OSL disks from the holders before inserting them inside a standard ATOM phantom for dose measurements. The authors solved three technical difficulties introduced by this modification: (1) energy dependent dose calibration for raw OSL readings; (2) influence of the brief background exposure of OSL disks to dimmed room light; (3) correct pairing between the dose readings and measurement locations. The authors acquired 100 dose measurements at various positions in the phantom, which was scanned using a clinical chest protocol with both angular and z-axis tube current modulations. Results: Dose calibration was performed according to the beam qualities inside the phantom as determined from an established Monte Carlo model of the scanner. The influence of the brief exposure to dimmed room light was evaluated and deemed negligible. Pairing between the OSL readings and measurement locations was ensured by the experimental design. The organ doses measured for a routine adult chest scan protocol ranged from 9.4 to 18.8 mGy, depending on the composition, location, and surrounding anatomy of the organs. The dose distribution across different slices of the phantom strongly depended on the z-axis mA modulation. In the same slice, doses to the soft tissues other than the spinal cord demonstrated relatively small variations, with the maximum COV around 11.4%. This might be attributed to the angular mA modulation, the placement of the dosimeters, the chest cavity of the scanned region, and the size of the phantom. Doses to the spinal cord were consistently lower than those to other soft tissues. Conclusions: The method is suited for acquiring densely sampled organ dose maps, and can be used for studying dose distributions relevant to subject size, organ location, and clinical CT protocols. PMID:23927332

A method to acquire CT organ dose map using OSL dosimeters and ATOM anthropomorphic phantoms.

PubMed

Zhang, Da; Li, Xinhua; Gao, Yiming; Xu, X George; Liu, Bob

2013-08-01

To present the design and procedure of an experimental method for acquiring densely sampled organ dose map for CT applications, based on optically stimulated luminescence (OSL) dosimeters "nanoDots" and standard ATOM anthropomorphic phantoms; and to provide the results of applying the method--a dose data set with good statistics for the comparison with Monte Carlo simulation result in the future. A standard ATOM phantom has densely located holes (in 3×3 cm or 1.5×1.5 cm grids), which are too small (5 mm in diameter) to host many types of dosimeters, including the nanoDots. The authors modified the conventional way in which nanoDots are used, by removing the OSL disks from the holders before inserting them inside a standard ATOM phantom for dose measurements. The authors solved three technical difficulties introduced by this modification: (1) energy dependent dose calibration for raw OSL readings; (2) influence of the brief background exposure of OSL disks to dimmed room light; (3) correct pairing between the dose readings and measurement locations. The authors acquired 100 dose measurements at various positions in the phantom, which was scanned using a clinical chest protocol with both angular and z-axis tube current modulations. Dose calibration was performed according to the beam qualities inside the phantom as determined from an established Monte Carlo model of the scanner. The influence of the brief exposure to dimmed room light was evaluated and deemed negligible. Pairing between the OSL readings and measurement locations was ensured by the experimental design. The organ doses measured for a routine adult chest scan protocol ranged from 9.4 to 18.8 mGy, depending on the composition, location, and surrounding anatomy of the organs. The dose distribution across different slices of the phantom strongly depended on the z-axis mA modulation. In the same slice, doses to the soft tissues other than the spinal cord demonstrated relatively small variations, with the maximum COV around 11.4%. This might be attributed to the angular mA modulation, the placement of the dosimeters, the chest cavity of the scanned region, and the size of the phantom. Doses to the spinal cord were consistently lower than those to other soft tissues. The method is suited for acquiring densely sampled organ dose maps, and can be used for studying dose distributions relevant to subject size, organ location, and clinical CT protocols.

A method to acquire CT organ dose map using OSL dosimeters and ATOM anthropomorphic phantoms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Da; Li, Xinhua; Liu, Bob

Purpose: To present the design and procedure of an experimental method for acquiring densely sampled organ dose map for CT applications, based on optically stimulated luminescence (OSL) dosimeters “nanoDots” and standard ATOM anthropomorphic phantoms; and to provide the results of applying the method—a dose data set with good statistics for the comparison with Monte Carlo simulation result in the future.Methods: A standard ATOM phantom has densely located holes (in 3 × 3 cm or 1.5 × 1.5 cm grids), which are too small (5 mm in diameter) to host many types of dosimeters, including the nanoDots. The authors modified themore » conventional way in which nanoDots are used, by removing the OSL disks from the holders before inserting them inside a standard ATOM phantom for dose measurements. The authors solved three technical difficulties introduced by this modification: (1) energy dependent dose calibration for raw OSL readings; (2) influence of the brief background exposure of OSL disks to dimmed room light; (3) correct pairing between the dose readings and measurement locations. The authors acquired 100 dose measurements at various positions in the phantom, which was scanned using a clinical chest protocol with both angular and z-axis tube current modulations.Results: Dose calibration was performed according to the beam qualities inside the phantom as determined from an established Monte Carlo model of the scanner. The influence of the brief exposure to dimmed room light was evaluated and deemed negligible. Pairing between the OSL readings and measurement locations was ensured by the experimental design. The organ doses measured for a routine adult chest scan protocol ranged from 9.4 to 18.8 mGy, depending on the composition, location, and surrounding anatomy of the organs. The dose distribution across different slices of the phantom strongly depended on the z-axis mA modulation. In the same slice, doses to the soft tissues other than the spinal cord demonstrated relatively small variations, with the maximum COV around 11.4%. This might be attributed to the angular mA modulation, the placement of the dosimeters, the chest cavity of the scanned region, and the size of the phantom. Doses to the spinal cord were consistently lower than those to other soft tissues.Conclusions: The method is suited for acquiring densely sampled organ dose maps, and can be used for studying dose distributions relevant to subject size, organ location, and clinical CT protocols.« less

Application of a wide-field phantom eye for optical coherence tomography and reflectance imaging.

PubMed

Corcoran, Anthony; Muyo, Gonzalo; van Hemert, Jano; Gorman, Alistair; Harvey, Andrew R

2015-12-15

Optical coherence tomography (OCT) and reflectance imaging are used in clinical practice to measure the thickness and transverse dimensions of retinal features. The recent trend towards increasing the field of view (FOV) of these devices has led to an increasing significance of the optical aberrations of both the human eye and the device. We report the design, manufacture and application of the first phantom eye that reproduces the off-axis optical characteristics of the human eye, and allows the performance assessment of wide-field ophthalmic devices. We base our design and manufacture on the wide-field schematic eye, [Navarro, R. J. Opt. Soc. Am. A , 1985, 2 .] as an accurate proxy to the human eye and enable assessment of ophthalmic imaging performance for a [Formula: see text] external FOV. We used multi-material 3D-printed retinal targets to assess imaging performance of the following ophthalmic instruments: the Optos 200Tx, Heidelberg Spectralis, Zeiss FF4 fundus camera and Optos OCT SLO and use the phantom to provide an insight into some of the challenges of wide-field OCT.

Carotid artery phantom designment and simulation using field II

NASA Astrophysics Data System (ADS)

Lin, Yuan; Yang, Xin; Ding, Mingyue

2013-10-01

Carotid atherosclerosis is the major cause of ischemic stroke, a leading cause of mortality and disability. Morphology and structure features of carotid plaques are the keys to identify plaques and monitoring the disease. Manually segmentation on the ultrasonic images to get the best-fitted actual size of the carotid plaques based on physicians personal experience, namely "gold standard", is a important step in the study of plaque size. However, it is difficult to qualitatively measure the segmentation error caused by the operator's subjective factors. In order to reduce the subjective factors, and the uncertainty factors of quantification, the experiments in this paper were carried out. In this study, we firstly designed a carotid artery phantom, and then use three different beam-forming algorithms of medical ultrasound to simulate the phantom. Finally obtained plaques areas were analyzed through manual segmentation on simulation images. We could (1) directly evaluate the different beam-forming algorithms for the ultrasound imaging simulation on the effect of carotid artery; (2) also analyze the sensitivity of detection on different size of plaques; (3) indirectly reflect the accuracy of the manual segmentation base on segmentation results the evaluation.

High-Fidelity Computational Aerodynamics of Multi-Rotor Unmanned Aerial Vehicles

NASA Technical Reports Server (NTRS)

Ventura Diaz, Patricia; Yoon, Seokkwan

2018-01-01

High-fidelity Computational Fluid Dynamics (CFD) simulations have been carried out for several multi-rotor Unmanned Aerial Vehicles (UAVs). Three vehicles have been studied: the classic quadcopter DJI Phantom 3, an unconventional quadcopter specialized for forward flight, the SUI Endurance, and an innovative concept for Urban Air Mobility (UAM), the Elytron 4S UAV. The three-dimensional unsteady Navier-Stokes equations are solved on overset grids using high-order accurate schemes, dual-time stepping, and a hybrid turbulence model. The DJI Phantom 3 is simulated with different rotors and with both a simplified airframe and the real airframe including landing gear and a camera. The effects of weather are studied for the DJI Phantom 3 quadcopter in hover. The SUI En- durance original design is compared in forward flight to a new configuration conceived by the authors, the hybrid configuration, which gives a large improvement in forward thrust. The Elytron 4S UAV is simulated in helicopter mode and in airplane mode. Understanding the complex flows in multi-rotor vehicles will help design quieter, safer, and more efficient future drones and UAM vehicles.

Application of a wide-field phantom eye for optical coherence tomography and reflectance imaging

NASA Astrophysics Data System (ADS)

Corcoran, Anthony; Muyo, Gonzalo; van Hemert, Jano; Gorman, Alistair; Harvey, Andrew R.

2015-12-01

Optical coherence tomography (OCT) and reflectance imaging are used in clinical practice to measure the thickness and transverse dimensions of retinal features. The recent trend towards increasing the field of view (FOV) of these devices has led to an increasing significance of the optical aberrations of both the human eye and the device. We report the design, manufacture and application of the first phantom eye that reproduces the off-axis optical characteristics of the human eye, and allows the performance assessment of wide-field ophthalmic devices. We base our design and manufacture on the wide-field schematic eye, [Navarro, R. J. Opt. Soc. Am. A, 1985, 2.] as an accurate proxy to the human eye and enable assessment of ophthalmic imaging performance for a ? external FOV. We used multi-material 3D-printed retinal targets to assess imaging performance of the following ophthalmic instruments: the Optos 200Tx, Heidelberg Spectralis, Zeiss FF4 fundus camera and Optos OCT SLO and use the phantom to provide an insight into some of the challenges of wide-field OCT.

A wideband spiral antenna for ingestible capsule endoscope systems: experimental results in a human phantom and a pig.

PubMed

Lee, Sang Heun; Lee, Jaebok; Yoon, Young Joong; Park, Sangbok; Cheon, Changyul; Kim, Kihyun; Nam, Sangwook

2011-06-01

This paper presents the design of a wideband spiral antenna for ingestible capsule endoscope systems and a comparison between the experimental results in a human phantom and a pig under general anesthesia. As wireless capsule endoscope systems transmit real-time internal biological image data at a high resolution to external receivers and because they operate in the human body, a small wideband antenna is required. To incorporate these properties, a thick-arm spiral structure is applied to the designed antenna. To make practical and efficient use of antennas inside the human body, which is composed of a high dielectric and lossy material, the resonance characteristics and radiation patterns were evaluated through a measurement setup using a liquid human phantom. The total height of the designed antenna is 5 mm and the diameter is 10 mm. The fractional bandwidth of the fabricated antenna is about 21% with a voltage standing-wave ratio of less than 2, and it has an isotropic radiation pattern. These characteristics are suitable for wideband capsule endoscope systems. Moreover, the received power level was measured using the proposed antenna, a circular polarized receiver antenna, and a pig under general anesthesia. Finally, endoscopic capsule images in the stomach and large intestine were captured using an on-off keying transceiver system.

SU-E-T-109: Development of An End-To-End Test for the Varian TrueBeamtm with a Novel Multiple-Dosimetric Modality H and N Phantom

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zakjevskii, V; Knill, C; Rakowski, J

2014-06-01

Purpose: To develop a comprehensive end-to-end test for Varian's TrueBeam linear accelerator for head and neck IMRT using a custom phantom designed to utilize multiple dosimetry devices. Methods: The initial end-to-end test and custom H and N phantom were designed to yield maximum information in anatomical regions significant to H and N plans with respect to: i) geometric accuracy, ii) dosimetric accuracy, and iii) treatment reproducibility. The phantom was designed in collaboration with Integrated Medical Technologies. A CT image was taken with a 1mm slice thickness. The CT was imported into Varian's Eclipse treatment planning system, where OARs and themore » PTV were contoured. A clinical template was used to create an eight field static gantry angle IMRT plan. After optimization, dose was calculated using the Analytic Anisotropic Algorithm with inhomogeneity correction. Plans were delivered with a TrueBeam equipped with a high definition MLC. Preliminary end-to-end results were measured using film and ion chambers. Ion chamber dose measurements were compared to the TPS. Films were analyzed with FilmQAPro using composite gamma index. Results: Film analysis for the initial end-to-end plan with a geometrically simple PTV showed average gamma pass rates >99% with a passing criterion of 3% / 3mm. Film analysis of a plan with a more realistic, ie. complex, PTV yielded pass rates >99% in clinically important regions containing the PTV, spinal cord and parotid glands. Ion chamber measurements were on average within 1.21% of calculated dose for both plans. Conclusion: trials have demonstrated that our end-to-end testing methods provide baseline values for the dosimetric and geometric accuracy of Varian's TrueBeam system.« less

A multi-purpose electromagnetic actuator for magnetic resonance elastography.

PubMed

Feng, Yuan; Zhu, Mo; Qiu, Suhao; Shen, Ping; Ma, Shengyuan; Zhao, Xuefeng; Hu, Chun-Hong; Guo, Liang

2018-04-19

An electromagnetic actuator was designed for magnetic resonance elastography (MRE). The actuator is unique in that it is simple, portable, and capable of brain, abdomen, and phantom imagings. A custom-built control unit was used for controlling the vibration frequency and synchronizing the trigger signals. An actuation unit was built and mounted on the specifically designed clamp and holders for different imaging applications. MRE experiments with respect to gel phantoms, brain, and liver showed that the actuator could produce stable and consistent mechanical waves. Estimated shear modulus using local frequency estimate method demonstrated that the measurement results were in line with that from MRE studies using different actuation systems. The relatively easy setup procedure and simple design indicated that the actuator system had the potential to be applied in many different clinical studies. Copyright © 2018 Elsevier Inc. All rights reserved.

Expedition 26 Crewmembers pose with European Matroshka-R Phantom Experiment

NASA Image and Video Library

2011-03-11

ISS026-E-033131 (11 March 2011) --- Russian cosmonauts Alexander Kaleri (left foreground), Oleg Skripochka (right foreground), Dmitry Kondratyev (left background) and European Space Agency astronaut Paolo Nespoli, all Expedition 26 flight engineers, pose for a photo with the European Matroshka-R Phantom experiment in the Zarya Functional Cargo Block (FGB) of the International Space Station. Matroshka, the name for the traditional Russian set of nestling dolls, is an antroph-amorphous model of a human torso designed for radiation studies.

Comparison of Fixed-Stabilizer, Adjustable-Stabilizer and All-Moveable Horizontal Tails

DTIC Science & Technology

1945-10-01

the thrust axis and wind direction at Infinity, degrees; primed to indicate that a is corrected for ground interference effects 5 angular ...deflection of control surface, degrees i+- maximum angular deflection of stabilizer measured with reference to thrust axis, degrees hnax...5e maximum negative angular deflection of elevator, degrees E downwash angle at teil, degrees; primed to indicate that e Is

Studying Hooke's Law by Using a Pogo Stick

ERIC Educational Resources Information Center

Silva, Nicolas

2011-01-01

Perhaps the pogo stick was little Robert Hooke's favorite childhood toy, consisting of a stiff spring inserted in a tube fixed at the upper end and connected to a moveable rod at the other. Hand grips and a foot rest are connected to the tube. The idea is to jump on it taking advantage of the force provided by the spring when it is compressed.…

Pressure transducer

DOEpatents

Anderson, T.T.; Roop, C.J.; Schmidt, K.J.; Gunchin, E.R.

1987-02-13

A pressure transducer suitable for use in high temperature environments includes two pairs of induction coils, each pair being bifilarly wound together, and each pair of coils connected as opposite arms of a four arm circuit; an electrically conductive target moveably positioned between the coil pairs and connected to a diaphragm such that deflection of the diaphragm causes axial movement of the target and an unbalance in the bridge output. 7 figs.

Vacuum pump apparatus

DOEpatents

Batzer, Thomas H.; Call, Wayne R.

1985-01-01

An improved cryopumping apparatus which comprises a cryopumping space which may be alternately opened and closed from the surrounding area by moveable panels, trubular cryopanels within said cryopumping space through which a coolant such as liquid helium may be passed, and an apparatus for spraying liquid argon onto said cylindrical cryopanels in order to enhance the cryogenic entrapment of such low-z ions, atoms, and molecules as hydrogen and helium.

Positioning, Splinting, and Contracture Management

DTIC Science & Technology

2011-01-01

IP) joints in extension, thumb in palmar abduction, hip extension and abducted 20 (no external rotation), knee extension, and neutral ankle ...to skin breakdown are the heels,55 sacrum, ankles , wrists, elbows, and occipital area.8 Some options for splinting and positioning devices can be...children.70 In addition, moveable parts are difficult to anchor to small levers and the cognition and responsibilities needed for proper fit of dynamic

Pressure transducer

DOEpatents

Anderson, Thomas T.; Roop, Conard J.; Schmidt, Kenneth J.; Gunchin, Elmer R.

1989-01-01

A pressure transducer suitable for use in high temperature environments includes two pairs of induction coils, each pair being bifilarly wound together, and each pair of coils connected as opposite arms of a four arm circuit; an electrically conductive target moveably positioned between the coil pairs and connected to a diaphragm such that deflection of the diaphragm causes axial movement of the target and an unbalance in the bridge output.

Comparison of Head Scatter Factor for 6MV and 10MV flattened (FB) and Unflattened (FFF) Photon Beam using indigenously Designed Columnar Mini Phantom.

PubMed

Ashokkumar, Sigamani; Nambi Raj, N Arunai; Sinha, Sujit Nath; Yadav, Girigesh; Thiyagarajan, Rajesh; Raman, Kothanda; Mishra, Manindra Bhushan

2014-07-01

To measure and compare the head scatter factor for flattened (FB) and unflattened (FFF) of 6MV and 10MV photon beam using indigenously designed mini phantom. A columnar mini phantom was designed as recommended by AAPM Task Group 74 with low and high atomic number materials at 10 cm (mini phantom) and at approximately twice the depth of maximum dose water equivalent thickness (brass build-up cap). Scatter in the accelerator (Sc) values of 6MV-FFF photon beams are lesser than that of the 6MV-FB photon beams (0.66-2.8%; Clinac iX, 2300CD) and (0.47-1.74%; True beam) for field sizes ranging from 10 × 10 cm(2) to 40 × 40 cm(2). Sc values of 10MV-FFF photon beams are lesser (0.61-2.19%; True beam) than that of the 10MV-FB photons beams for field sizes ranging from 10 × 10 cm(2) to 40 × 40 cm(2). The SSD had no influence on head scatter for both flattened and unflattened beams and irrespective of head design of the different linear accelerators. The presence of field shaping device influences the Sc values. The collimator exchange effect reveals that the opening of the upper jaw increases Sc irrespective of FB or FFF photon beams and different linear accelerators, and it is less significant in FFF beams. Sc values of 6MV-FB square field were in good agreement with that of AAPM, TG-74 published data for Varian (Clinac iX, 2300CD) accelerator. Our results confirm that the removal of flattening filter decreases in the head scatter factor compared to flattened beam. This could reduce the out-of-field dose in advanced treatment delivery techniques.

Comparison of Head Scatter Factor for 6MV and 10MV flattened (FB) and Unflattened (FFF) Photon Beam using indigenously Designed Columnar Mini Phantom

PubMed Central

Ashokkumar, Sigamani; Nambi Raj, N Arunai; Sinha, Sujit Nath; Yadav, Girigesh; Thiyagarajan, Rajesh; Raman, Kothanda; Mishra, Manindra Bhushan

2014-01-01

To measure and compare the head scatter factor for flattened (FB) and unflattened (FFF) of 6MV and 10MV photon beam using indigenously designed mini phantom. A columnar mini phantom was designed as recommended by AAPM Task Group 74 with low and high atomic number materials at 10 cm (mini phantom) and at approximately twice the depth of maximum dose water equivalent thickness (brass build-up cap). Scatter in the accelerator (Sc) values of 6MV-FFF photon beams are lesser than that of the 6MV-FB photon beams (0.66-2.8%; Clinac iX, 2300CD) and (0.47-1.74%; True beam) for field sizes ranging from 10 × 10 cm2 to 40 × 40 cm2. Sc values of 10MV-FFF photon beams are lesser (0.61-2.19%; True beam) than that of the 10MV-FB photons beams for field sizes ranging from 10 × 10 cm2 to 40 × 40 cm2. The SSD had no influence on head scatter for both flattened and unflattened beams and irrespective of head design of the different linear accelerators. The presence of field shaping device influences the Sc values. The collimator exchange effect reveals that the opening of the upper jaw increases Sc irrespective of FB or FFF photon beams and different linear accelerators, and it is less significant in FFF beams. Sc values of 6MV-FB square field were in good agreement with that of AAPM, TG-74 published data for Varian (Clinac iX, 2300CD) accelerator. Our results confirm that the removal of flattening filter decreases in the head scatter factor compared to flattened beam. This could reduce the out-of-field dose in advanced treatment delivery techniques. PMID:25190997

Visualizing Motion Patterns in Acupuncture Manipulation.

PubMed

Lee, Ye-Seul; Jung, Won-Mo; Lee, In-Seon; Lee, Hyangsook; Park, Hi-Joon; Chae, Younbyoung

2016-07-16

Acupuncture manipulation varies widely among practitioners in clinical settings, and it is difficult to teach novice students how to perform acupuncture manipulation techniques skillfully. The Acupuncture Manipulation Education System (AMES) is an open source software system designed to enhance acupuncture manipulation skills using visual feedback. Using a phantom acupoint and motion sensor, our method for acupuncture manipulation training provides visual feedback regarding the actual movement of the student's acupuncture manipulation in addition to the optimal or intended movement, regardless of whether the manipulation skill is lifting, thrusting, or rotating. Our results show that students could enhance their manipulation skills by training using this method. This video shows the process of manufacturing phantom acupoints and discusses several issues that may require the attention of individuals interested in creating phantom acupoints or operating this system.

Design and validation of a mathematical breast phantom for contrast-enhanced digital mammography

NASA Astrophysics Data System (ADS)

Hill, Melissa L.; Mainprize, James G.; Jong, Roberta A.; Yaffe, Martin J.

2011-03-01

In contrast-enhanced digital mammography (CEDM) an iodinated contrast agent is employed to increase lesion contrast and to provide tissue functional information. Here, we present the details of a software phantom that can be used as a tool for the simulation of CEDM images, and compare the degree of anatomic noise present in images simulated using the phantom to that associated with breast parenchyma in clinical CEDM images. Such a phantom could be useful for multiparametric investigations including characterization of CEDM imaging performance and system optimization. The phantom has a realistic mammographic appearance based on a clustered lumpy background and models contrast agent uptake according to breast tissue physiology. Fifty unique phantoms were generated and used to simulate regions of interest (ROI) of pre-contrast images and logarithmically subtracted CEDM images using monoenergetic ray tracing. Power law exponents, β, were used as a measure of anatomic noise and were determined using a linear least-squares fit to log-log plots of the square of the modulus of radially averaged image power spectra versus spatial frequency. The power spectra for ROI selected from regions of normal parenchyma in 10 pairs of clinical CEDM pre-contrast and subtracted images were also measured for comparison with the simulated images. There was good agreement between the measured β in the simulated CEDM images and the clinical images. The values of β were consistently lower for the logarithmically subtracted CEDM images compared to the pre-contrast images, indicating that the subtraction process reduced anatomical noise.

Prevention of hypothyroidism related to mantle irradiation for Hodgkin's disease: Preparative phantom study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marcial-Vega, V.A.; Order, S.E.; Lastner, G.

1990-03-01

To decrease the incidence of hypothyroidism related to mantle irradiation for Hodgkin's disease, we initiated a study designed to protect the thyroid gland using a phantom. A thyroid phantom was filled with technetium-99m. The thyroid phantom was placed inside of its corresponding anterior neck position in a whole body phantom. An anterior scintiscan of the head and neck region demonstrated the radioactivity in the simulated thyroid. A mantle port included a focused block that would shield the thyroid from the anterior port. The phantom was exposed (4 MeV) to 180 cGy (AP-PA) at midplane with lithium fluoride dosimeters in themore » position of the thyroid. The thyroid received an average of 12 cGy from the anterior field and 48 cGy from the posterior field for a total of 60 cGy per treatment or 30% of the prescribed dose. A complete mantle field course of radiation of 4000 cGy would lead to a thyroid dose of 1200 cGy at a daily fractional dose of 60 cGy. We elected not to block the thyroid from the posterior field to prevent shielding and potential underdosage of involved nodal sites. The present study suggests a method of safe and effective thyroid shielding which needs to be tested clinically to determine whether it would reduce the incidence of chemical and clinical hypothyroidism or simply extend the period until occurrence.« less

Polyvinyl chloride plastisol breast phantoms for ultrasound imaging.

PubMed

de Carvalho, Isabela Miller; De Matheo, Lucas Lobianco; Costa Júnior, José Francisco Silva; Borba, Cecília de Melo; von Krüger, Marco Antonio; Infantosi, Antonio Fernando Catelli; Pereira, Wagner Coelho de Albuquerque

2016-08-01

Ultrasonic phantoms are objects that mimic some features of biological tissues, allowing the study of their interactions with ultrasound (US). In the diagnostic-imaging field, breast phantoms are an important tool for testing performance and optimizing US systems, as well as for training medical professionals. This paper describes the design and manufacture of breast lesions by using polyvinyl chloride plastisol (PVCP) as the base material. Among the materials available for this study, PVCP was shown to be stable, durable, and easy to handle. Furthermore, it is a nontoxic, nonpolluting, and low-cost material. The breast's glandular tissue (image background) was simulated by adding graphite powder with a concentration of 1% to the base material. Mixing PVCP and graphite powder in differing concentrations allows one to simulate lesions with different echogenicity patterns (anechoic, hypoechoic, and hyperechoic). From this mixture, phantom materials were obtained with speed of sound varying from 1379.3 to 1397.9ms(-1) and an attenuation coefficient having values between 0.29 and 0.94dBcm(-1) for a frequency of 1MHz at 24°C. A single layer of carnauba wax was added to the lesion surface in order to evaluate its applicability for imaging. The images of the phantoms were acquired using commercial ultrasound equipment; a specialist rated the images, elaborating diagnoses representative of both benign and malignant lesions. The results indicated that it was possible to easily create a phantom by using low-cost materials, readily available in the market and stable at room temperature, as the basis of ultrasonic phantoms that reproduce the image characteristics of fatty breast tissue and typical lesions of the breast. Copyright © 2016 Elsevier B.V. All rights reserved.

Development and test of sets of 3D printed age-specific thyroid phantoms for 131I measurements

NASA Astrophysics Data System (ADS)

Beaumont, Tiffany; Caldeira Ideias, Pedro; Rimlinger, Maeva; Broggio, David; Franck, Didier

2017-06-01

In the case of a nuclear reactor accident the release contains a high proportion of iodine-131 that can be inhaled or ingested by members of the public. Iodine-131 is naturally retained in the thyroid and increases the thyroid cancer risk. Since the radiation induced thyroid cancer risk is greater for children than for adults, the thyroid dose to children should be assessed as accurately as possible. For that purpose direct measurements should be carried out with age-specific calibration factors but, currently, there is no age-specific thyroid phantoms allowing a robust measurement protocol. A set of age-specific thyroid phantoms for 5, 10, 15 year old children and for the adult has been designed and 3D printed. A realistic thyroid shape has been selected and material properties taken into account to simulate the attenuation of biological tissues. The thyroid volumes follow ICRP recommendations and the phantoms also include the trachea and a spine model. Several versions, with or without spine, with our without trachea, with or without age-specific neck have been manufactured, in order to study the influence of these elements on calibration factors. The calibration factor obtained with the adult phantom and a reference phantom are in reasonable agreement. In vivo calibration experiments with germanium detectors have shown that the difference in counting efficiency, the inverse of the calibration factor, between the 5 year and adult phantoms is 25% for measurement at contact. It is also experimentally evidenced that the inverse of the calibration factor varies linearly with the thyroid volume. The influence of scattering elements like the neck or spine is not evidenced by experimental measurements.

γTools: A modular multifunction phantom for quality assurance in GammaKnife treatments.

PubMed

Calusi, Silvia; Noferini, Linhsia; Marrazzo, Livia; Casati, Marta; Arilli, Chiara; Compagnucci, Antonella; Talamonti, Cinzia; Scoccianti, Silvia; Greto, Daniela; Bordi, Lorenzo; Livi, Lorenzo; Pallotta, Stefania

2017-11-01

We present the γTools, a new phantom designed to assess geometric and dosimetric accuracy in Gamma Knife treatments, together with first tests and results of applications. The phantom is composed of two modules: the imaging module, a regular grid of 1660 control points to evaluate image distortions and image registration result and the dosimetry module for delivered dose distribution measurements. The phantom is accompanied by a MatLab routine for image distortions quantification. Dose measurement are performed with Gafchromic films fixed between two inserts and placed in various positions and orientations inside the dosimetry module thus covering a volume comparable to the full volume of a head. Tests performed to assess the accuracy and precision of the imaging module demonstrated sub-millimetric values. As an example of possible applications, the phantom was employed to measure image distortions of two MRI scanners and to perform dosimetric studies of single shots delivered to homogeneous and heterogeneous materials. Due to the phantom material, the measured absolute dose do not correspond to the planned dose; doses comparisons are thus carried out between normalized dose distributions. Finally, an end-to-end test was carried out in the treatment of a neuroma-like target which resulted in a 100% gamma passing rate (2% local, 2 mm) and a distance between the real target perimeter and the prescription isodose centroids of about 1 mm. The tests demonstrate that the proposed phantom is suitable to assess both the geometrical and relative dosimetric accuracy of Gamma Knife radiosurgery treatments. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Establishing High-Quality Prostate Brachytherapy Using a Phantom Simulator Training Program

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thaker, Nikhil G.; Kudchadker, Rajat J.; Swanson, David A.

2014-11-01

Purpose: To design and implement a unique training program that uses a phantom-based simulator to teach the process of prostate brachytherapy (PB) quality assurance and improve the quality of education. Methods and Materials: Trainees in our simulator program were practicing radiation oncologists, radiation oncology residents, and fellows of the American Brachytherapy Society. The program emphasized 6 core areas of quality assurance: patient selection, simulation, treatment planning, implant technique, treatment evaluation, and outcome assessment. Using the Iodine 125 ({sup 125}I) preoperative treatment planning technique, trainees implanted their ultrasound phantoms with dummy seeds (ie, seeds with no activity). Pre- and postimplant dosimetric parametersmore » were compared and correlated using regression analysis. Results: Thirty-one trainees successfully completed the simulator program during the period under study. The mean phantom prostate size, number of seeds used, and total activity were generally consistent between trainees. All trainees met the V100 >95% objective both before and after implantation. Regardless of the initial volume of the prostate phantom, trainees' ability to cover the target volume with at least 100% of the dose (V100) was not compromised (R=0.99 pre- and postimplant). However, the V150 had lower concordance (R=0.37) and may better reflect heterogeneity control of the implant process. Conclusions: Analysis of implants from this phantom-based simulator shows a high degree of consistency between trainees and uniformly high-quality implants with respect to parameters used in clinical practice. This training program provides a valuable educational opportunity that improves the quality of PB training and likely accelerates the learning curve inherent in PB. Prostate phantom implantation can be a valuable first step in the acquisition of the required skills to safely perform PB.« less

Electro-optically actuated liquid-lens zoom

NASA Astrophysics Data System (ADS)

Pütsch, O.; Loosen, P.

2012-06-01

Progressive miniaturization and mass market orientation denote a challenge to the design of dynamic optical systems such as zoom-lenses. Two working principles can be identified: mechanical actuation and application of active optical components. Mechanical actuation changes the focal length of a zoom-lens system by varying the axial positions of optical elements. These systems are limited in speed and often require complex coupled movements. However, well established optical design approaches can be applied. In contrast, active optical components change their optical properties by varying their physical structure by means of applying external electric signals. An example are liquidlenses which vary their curvatures to change the refractive power. Zoom-lenses benefit from active optical components in two ways: first, no moveable structures are required and second, fast response characteristics can be realized. The precommercial development of zoom-lenses demands simplified and cost-effective system designs. However the number of efficient optical designs for electro-optically actuated zoom-lenses is limited. In this paper, the systematic development of an electro-optically actuated zoom-lens will be discussed. The application of aberration polynomials enables a better comprehension of the primary monochromatic aberrations at the lens elements during a change in magnification. This enables an enhanced synthesis of the system behavior and leads to a simplified zoom-lens design with no moving elements. The change of focal length is achieved only by varying curvatures of targeted integrated electro-optically actuated lenses.

3D printing X-Ray Quality Control Phantoms. A Low Contrast Paradigm

NASA Astrophysics Data System (ADS)

Kapetanakis, I.; Fountos, G.; Michail, C.; Valais, I.; Kalyvas, N.

2017-11-01

Current 3D printing technology products may be usable in various biomedical applications. Such an application is the creation of X-ray quality control phantoms. In this work a self-assembled 3D printer (geeetech i3) was used for the design of a simple low contrast phantom. The printing material was Polylactic Acid (PLA) (100% printing density). Low contrast scheme was achieved by creating air-holes with different diameters and thicknesses, ranging from 1mm to 9mm. The phantom was irradiated at a Philips Diagnost 93 fluoroscopic installation at 40kV-70kV with the semi-automatic mode. The images were recorded with an Agfa cr30-x CR system and assessed with ImageJ software. The best contrast value observed was approximately 33%. In low contrast detectability check it was found that the 1mm diameter hole was always visible, for thickness larger or equal to 4mm. A reason for not being able to distinguish 1mm in smaller thicknesses might be the presence of printing patterns on the final image, which increased the structure noise. In conclusion the construction of a contrast resolution phantom with a 3D printer is feasible. The quality of the final product depends upon the printer accuracy and the material characteristics.

Image quality phantom and parameters for high spatial resolution small-animal SPECT

NASA Astrophysics Data System (ADS)

Visser, Eric P.; Harteveld, Anita A.; Meeuwis, Antoi P. W.; Disselhorst, Jonathan A.; Beekman, Freek J.; Oyen, Wim J. G.; Boerman, Otto C.

2011-10-01

At present, generally accepted standards to characterize small-animal single photon emission tomographs (SPECT) do not exist. Whereas for small-animal positron emission tomography (PET), the NEMA NU 4-2008 guidelines are available, such standards are still lacking for small-animal SPECT. More specifically, a dedicated image quality (IQ) phantom and corresponding IQ parameters are absent. The structures of the existing PET IQ phantom are too large to fully characterize the sub-millimeter spatial resolution of modern multi-pinhole SPECT scanners, and its diameter will not fit into all scanners when operating in high spatial resolution mode. We therefore designed and constructed an adapted IQ phantom with smaller internal structures and external diameter, and a facility to guarantee complete filling of the smallest rods. The associated IQ parameters were adapted from NEMA NU 4. An additional parameter, effective whole-body sensitivity, was defined since this was considered relevant in view of the variable size of the field of view and the use of multiple bed positions as encountered in modern small-animal SPECT scanners. The usefulness of the phantom was demonstrated for 99mTc in a USPECT-II scanner operated in whole-body scanning mode using a multi-pinhole mouse collimator with 0.6 mm pinhole diameter.

PROPERTIES OF PHANTOM TISSUE-LIKE POLYMETHYLPENTENE IN THE FREQUENCY RANGE 20–70 MHZ

PubMed Central

Madsen, Ernest L; Deaner, Meagan E; Mehi, James

2011-01-01

Quantitative ultrasound (QUS) has been employed to characterize soft tissues at ordinary abdominal ultrasound frequencies (2–15 MHz) and is beginning application at high frequencies (20–70 MHz). For example, backscatter and attenuation coefficients can be estimated in vivo using a reference phantom. At high frequencies it is crucial that reverberations do not compromise the measurements. Such reverberations can occur between the phantom's scanning window and transducer components as well as within the scanning window between its surfaces. Transducers are designed to minimize reverberations between the transducer and soft tissue. Thus, the acoustic impedance of a phantom scanning window should be tissue-like; polymethylpentene (TPX) is commonly used because of its tissue-like acoustic impedance. For QUS it is also crucial to correct for the transmission coefficient of the scanning window. Computation of the latter requires knowledge of the ultrasonic properties, viz, density, speed and attenuation coefficients. This work reports values for the ultrasonic properties of two versions of TPX over the high frequency range. One form (TPX film) is used as a scanning window on high frequency phantoms, and at 40 MHz and 22°C was found to have an attenuation coefficient of 120 dB/cm and a propagation speed of 2093 m/s. PMID:21723451

Control volume based hydrocephalus research; a phantom study

NASA Astrophysics Data System (ADS)

Cohen, Benjamin; Voorhees, Abram; Madsen, Joseph; Wei, Timothy

2009-11-01

Hydrocephalus is a complex spectrum of neurophysiological disorders involving perturbation of the intracranial contents; primarily increased intraventricular cerebrospinal fluid (CSF) volume and intracranial pressure are observed. CSF dynamics are highly coupled to the cerebral blood flows and pressures as well as the mechanical properties of the brain. Hydrocephalus, as such, is a very complex biological problem. We propose integral control volume analysis as a method of tracking these important interactions using mass and momentum conservation principles. As a first step in applying this methodology in humans, an in vitro phantom is used as a simplified model of the intracranial space. The phantom's design consists of a rigid container filled with a compressible gel. Within the gel a hollow spherical cavity represents the ventricular system and a cylindrical passage represents the spinal canal. A computer controlled piston pump supplies sinusoidal volume fluctuations into and out of the flow phantom. MRI is used to measure fluid velocity and volume change as functions of time. Independent pressure measurements and momentum flow rate measurements are used to calibrate the MRI data. These data are used as a framework for future work with live patients and normal individuals. Flow and pressure measurements on the flow phantom will be presented through the control volume framework.

MO-FG-209-05: Towards a Feature-Based Anthropomorphic Model Observer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Avanaki, A.

2016-06-15

This symposium will review recent advances in the simulation methods for evaluation of novel breast imaging systems – the subject of AAPM Task Group TG234. Our focus will be on the various approaches to development and validation of software anthropomorphic phantoms and their use in the statistical assessment of novel imaging systems using such phantoms along with computational models for the x-ray image formation process. Due to the dynamic development and complex design of modern medical imaging systems, the simulation of anatomical structures, image acquisition modalities, and the image perception and analysis offers substantial benefits of reduced cost, duration, andmore » radiation exposure, as well as the known ground-truth and wide variability in simulated anatomies. For these reasons, Virtual Clinical Trials (VCTs) have been increasingly accepted as a viable tool for preclinical assessment of x-ray and other breast imaging methods. Activities of TG234 have encompassed the optimization of protocols for simulation studies, including phantom specifications, the simulated data representation, models of the imaging process, and statistical assessment of simulated images. The symposium will discuss the state-of-the-science of VCTs for novel breast imaging systems, emphasizing recent developments and future directions. Presentations will discuss virtual phantoms for intermodality breast imaging performance comparisons, extension of the breast anatomy simulation to the cellular level, optimized integration of the simulated imaging chain, and the novel directions in the observer models design. Learning Objectives: Review novel results in developing and applying virtual phantoms for inter-modality breast imaging performance comparisons; Discuss the efforts to extend the computer simulation of breast anatomy and pathology to the cellular level; Summarize the state of the science in optimized integration of modules in the simulated imaging chain; Compare novel directions in the design of observer models for task based validation of imaging systems. PB: Research funding support from the NIH, NSF, and Komen for the Cure; NIH funded collaboration with Barco, Inc. and Hologic, Inc.; Consultant to Delaware State Univ. and NCCPM, UK. AA: Employed at Barco Healthcare.; P. Bakic, NIH: (NIGMS P20 #GM103446, NCI R01 #CA154444); M. Das, NIH Research grants.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Graff, C.

This symposium will review recent advances in the simulation methods for evaluation of novel breast imaging systems – the subject of AAPM Task Group TG234. Our focus will be on the various approaches to development and validation of software anthropomorphic phantoms and their use in the statistical assessment of novel imaging systems using such phantoms along with computational models for the x-ray image formation process. Due to the dynamic development and complex design of modern medical imaging systems, the simulation of anatomical structures, image acquisition modalities, and the image perception and analysis offers substantial benefits of reduced cost, duration, andmore » radiation exposure, as well as the known ground-truth and wide variability in simulated anatomies. For these reasons, Virtual Clinical Trials (VCTs) have been increasingly accepted as a viable tool for preclinical assessment of x-ray and other breast imaging methods. Activities of TG234 have encompassed the optimization of protocols for simulation studies, including phantom specifications, the simulated data representation, models of the imaging process, and statistical assessment of simulated images. The symposium will discuss the state-of-the-science of VCTs for novel breast imaging systems, emphasizing recent developments and future directions. Presentations will discuss virtual phantoms for intermodality breast imaging performance comparisons, extension of the breast anatomy simulation to the cellular level, optimized integration of the simulated imaging chain, and the novel directions in the observer models design. Learning Objectives: Review novel results in developing and applying virtual phantoms for inter-modality breast imaging performance comparisons; Discuss the efforts to extend the computer simulation of breast anatomy and pathology to the cellular level; Summarize the state of the science in optimized integration of modules in the simulated imaging chain; Compare novel directions in the design of observer models for task based validation of imaging systems. PB: Research funding support from the NIH, NSF, and Komen for the Cure; NIH funded collaboration with Barco, Inc. and Hologic, Inc.; Consultant to Delaware State Univ. and NCCPM, UK. AA: Employed at Barco Healthcare.; P. Bakic, NIH: (NIGMS P20 #GM103446, NCI R01 #CA154444); M. Das, NIH Research grants.« less

MO-DE-210-06: Development of a Supercompounded 3D Volumetric Ultrasound Image Guidance System for Prone Accelerated Partial Breast Irradiation (APBI)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chiu, T; Hrycushko, B; Zhao, B

2015-06-15

Purpose: For early-stage breast cancer, accelerated partial breast irradiation (APBI) is a cost-effective breast-conserving treatment. Irradiation in a prone position can mitigate respiratory induced breast movement and achieve maximal sparing of heart and lung tissues. However, accurate dose delivery is challenging due to breast deformation and lumpectomy cavity shrinkage. We propose a 3D volumetric ultrasound (US) image guidance system for accurate prone APBI Methods: The designed system, set beneath the prone breast board, consists of a water container, an US scanner, and a two-layer breast immobilization cup. The outer layer of the breast cup forms the inner wall of watermore » container while the inner layer is attached to patient breast directly to immobilization. The US transducer scans is attached to the outer-layer of breast cup at the dent of water container. Rotational US scans in a transverse plane are achieved by simultaneously rotating water container and transducer, and multiple transverse scanning forms a 3D scan. A supercompounding-technique-based volumetric US reconstruction algorithm is developed for 3D image reconstruction. The performance of the designed system is evaluated with two custom-made gelatin phantoms containing several cylindrical inserts filled in with water (11% reflection coefficient between materials). One phantom is designed for positioning evaluation while the other is for scaling assessment. Results: In the positioning evaluation phantom, the central distances between the inserts are 15, 20, 30 and 40 mm. The distances on reconstructed images differ by −0.19, −0.65, −0.11 and −1.67 mm, respectively. In the scaling evaluation phantom, inserts are 12.7, 19.05, 25.40 and 31.75 mm in diameter. Measured inserts’ sizes on images differed by 0.23, 0.19, −0.1 and 0.22 mm, respectively. Conclusion: The phantom evaluation results show that the developed 3D volumetric US system can accurately localize target position and determine target volume, and is a promising image-guidance tool for prone APBI.« less

Characterizing tissue microstructure using an ultrasound system-independent spatial autocorrelation function

NASA Astrophysics Data System (ADS)

Dong, Fang

1999-09-01

The research described in this dissertation is related to characterization of tissue microstructure using a system- independent spatial autocorrelation function (SAF). The function was determined using a reference phantom method, which employed a well-defined ``point- scatterer'' reference phantom to account for instrumental factors. The SAF's were estimated for several tissue-mimicking (TM) phantoms and fresh dog livers. Both phantom tests and in vitro dog liver measurements showed that the reference phantom method is relatively simple and fairly accurate, providing the bandwidth of the measurement system is sufficient for the size of the scatterer being involved in the scattering process. Implementation of this method in clinical scanner requires that distortions from patient's body wall be properly accounted for. The SAF's were estimated for two phantoms with body-wall-like distortions. The experimental results demonstrated that body wall distortions have little effect if echo data are acquired from a large scattering volume. One interesting application of the SAF is to form a ``scatterer size image''. The scatterer size image may help providing diagnostic tools for those diseases in which the tissue microstructure is different from the normal. Another method, the BSC method, utilizes information contained in the frequency dependence of the backscatter coefficient to estimate the scatterer size. The SAF technique produced accurate scatterer size images of homogeneous TM phantoms and the BSC method was capable of generating accurate size images for heterogeneous phantoms. In the scatterer size image of dog kidneys, the contrast-to-noise-ratio (CNR) between renal cortex and medulla was improved dramatically compared to the gray- scale image. The effect of nonlinear propagation was investigated by using a custom-designed phantom with overlaying TM fat layer. The results showed that the correlation length decreased when the transmitting power increased. The measurement results support the assumption that nonlinear propagation generates harmonic energies and causes underestimation of scatterer diameters. Nonlinear propagation can be further enhanced by those materials with high B/A value-a parameter which characterizes the degree of nonlinearity. Nine versions of TM fat and non-fat materials were measured for their B/A values using a new measurement technique, the ``simplified finite amplitude insertion substitution'' (SFAIS) method.

MO-F-CAMPUS-I-03: Tissue Equivalent Material Phantom to Test and Optimize Coherent Scatter Imaging for Tumor Classification

DOE Office of Scientific and Technical Information (OSTI.GOV)

Albanese, K; Morris, R; Lakshmanan, M

Purpose: To accurately model different breast geometries using a tissue equivalent phantom, and to classify these tissues in a coherent x-ray scatter imaging system. Methods: A breast phantom has been designed to assess the capability of coded aperture coherent x-ray scatter imaging system to classify different types of breast tissue (adipose, fibroglandular, tumor). The tissue-equivalent phantom was modeled as a hollow plastic cylinder containing multiple cylindrical and spherical inserts that can be positioned, rearranged, or removed to model different breast geometries. Each enclosure can be filled with a tissue-equivalent material and excised human tumors. In this study, beef and lard,more » placed inside 2-mm diameter plastic Nalgene containers, were used as surrogates for fibroglandular and adipose tissue, respectively. The phantom was imaged at 125 kVp, 40 mA for 10 seconds each with a 1-mm pencil beam. The raw data were reconstructed using a model-based reconstruction algorithm and yielded the location and form factor, or momentum transfer (q) spectrum of the materials that were imaged. The measured material form factors were then compared to the ground truth measurements acquired by x-ray diffraction (XRD) imaging. Results: The tissue equivalent phantom was found to accurately model different types of breast tissue by qualitatively comparing our measured form factors to those of adipose and fibroglandular tissue from literature. Our imaging system has been able to define the location and composition of the various materials in the phantom. Conclusion: This work introduces a new tissue equivalent phantom for testing and optimization of our coherent scatter imaging system for material classification. In future studies, the phantom will enable the use of a variety of materials including excised human tissue specimens in evaluating and optimizing our imaging system using pencil- and fan-beam geometries. United States Department of Homeland Security Duke University Medical Center - Department of Radiology Carl E Ravin Advanced Imaging Laboratories Duke University Medical Physics Graduate Program.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mandapaka, A; Ghebremedhin, A; Patyal, B

Purpose: To validate the treatment planning system predicted proton dose beyond a heterogeneity (n-BCA glue) by making a measurement in a custom acrylic phantom. Methods: A custom cubic acrylic phantom was designed for this experiment. A container was designed to fit in the phantom. This container was filled with TRUFILL™ n-Butyl Cyanoacrylate(n-BCA) glue. When the container was placed in the phantom, its center was at a distance of 7.4cm from the entrance. This depth allows us to make measurements around the center of modulation of a 126 MeV proton beam with a 3cm spread-out-Bragg peak. To make measurements at othermore » beam energies, additional acrylic can be added in front of the phantom, to adjust the depth of the heterogeneity. A diamond detector was cross calibrated against a standard cylindrical ion chamber in a 126MeV beam. The diamond detector was then used to make dose measurements beyond the inhomogeneity. The measurement was repeated with the container filled with water. Several measurements were made at each setup, to check reproducibility of measurements. Results: For the same number of Tic3R1 counts, the dose measured with the diamond detector beyond n-BCA glue was 1.053 times the dose measured beyond the water filled container. This result is in agreement with the measured stopping power of glue (1.06). These measurements were in agreement with the dose predicted by the treatment planning system when the electron density of the heterogeneity was replaced with 1.06 before the dose calculation. Conclusion: Our initial measurements validate the dose predicted by our treatment plan in the presence of heterogeneity in a phantom. The material tested (n-BCA glue) is commonly used in the treatment of AVM’s prior to an SRS treatment. An error in dose predicted by the treatment plan in the presence of the glue can be detrimental in a single fraction high dose SRS treatment I received the n-BCA liquid embolic system samples from Codman and Shurtleff, Inc.« less

SU-G-IeP3-09: Investigating the Interplay of Antiscatter Grids with Modern Detectors and Image Processing in Digital Radiography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sanchez, A; Little, K; Baad, M

Purpose: To use phantom and simulation experiments to relate technique factors, patient size and antiscatter grid use to image quality in portable digital radiography (DR), in light of advancements in detector design and image processing. Methods: Image contrast-to-noise ratio (CNR) on a portable DR system (MobileDaRt Evolution, Shimadzu) was measured by imaging four aluminum inserts of varying thickness, superimposed on a Lucite slab phantom using a pediatric abdominal protocol. Three thicknesses of Lucite were used: 6.1cm, 12cm, and 18.2cm, with both 55 and 65 kVp beams. The mAs was set so that detector entrance exposure (DEE) was matched between kVpmore » values. Each technique and phantom was used with and without an antiscatter grid (focused linear grid embedded in aluminum with an 8:1 ratio). The CNR-improvement-factor was then used to determine the thickness- and technique-dependent appropriateness of grid use. Finally, the same experiment was performed via Monte Carlo simulation, integrating incident energy fluence at each detector pixel, so that effects of detector design and image processing could be isolated from physical factors upstream of the detector. Results: The physical phantom experiment demonstrated a clear improvement for the lower tube voltage (55kVp), along with substantial CNR benefits with grid use for 12–18cm phantoms. Neither trend was evident with Monte Carlo, suggesting that suboptimal quantum-detection-efficiency and automated grid-removal could explain trends in kVp and grid use, respectively. Conclusion: Physical experiments demonstrate marked improvement in CNR when using a grid for phantoms of 12 and 18cm Lucite thickness (above ∼10cm soft-tissue equivalent). This benefit is likely due to image processing, as this result was not seen with Monte Carlo. The impact of image processing on image resolution should also be investigated, and the CNR benefit of low kVp and grid use should be weighed against the increased exposure time necessary to achieve adequate DEE.« less

Evaluation of 3D printing materials for fabrication of a novel multi-functional 3D thyroid phantom for medical dosimetry and image quality

NASA Astrophysics Data System (ADS)

Alssabbagh, Moayyad; Tajuddin, Abd Aziz; Abdulmanap, Mahayuddin; Zainon, Rafidah

2017-06-01

Recently, the three-dimensional printer has started to be utilized strongly in medical industries. In the human body, many parts or organs can be printed from 3D images to meet accurate organ geometries. In this study, five common 3D printing materials were evaluated in terms of their elementary composition and the mass attenuation coefficients. The online version of XCOM photon cross-section database was used to obtain the attenuation values of each material. The results were compared with the attenuation values of the thyroid listed in the International Commission on Radiation Units and Measurements - ICRU 44. Two original thyroid models (hollow-inside and solid-inside) were designed from scratch to be used in nuclear medicine, diagnostic radiology and radiotherapy for dosimetry and image quality purposes. Both designs have three holes for installation of radiation dosimeters. The hollow-inside model has more two holes in the top for injection the radioactive materials. The attenuation properties of the Polylactic Acid (PLA) material showed a very good match with the thyroid tissue, which it was selected to 3D print the phantom using open source RepRap, Prusa i3 3D printer. The scintigraphy images show that the phantom simulates a real healthy thyroid gland and thus it can be used for image quality purposes. The measured CT numbers of the PA material after the 3D printing show a close match with the human thyroid CT numbers. Furthermore, the phantom shows a good accommodation of the TLD dosimeters inside the holes. The 3D fabricated thyroid phantom simulates the real shape of the human thyroid gland with a changeable geometrical shape-size feature to fit different age groups. By using 3D printing technology, the time required to fabricate the 3D phantom was considerably shortened compared to the longer conventional methods, where it took only 30 min to print out the model. The 3D printing material used in this study is commercially available and cost-effective compared to current commercial tissue-equivalent materials.

Multiparameter double hole contrast detail phantom: Ability to detect image displacement due to off position anode stem

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pauzi, Nur Farahana; Majid, Zafri Azran Abdul; Sapuan, Abdul Halim

Contrast Detail phantom is a quality control tool to analyze the performance of imaging devices. Currently, its function is solely to evaluate the contrast detail characteristic of imaging system. It consists of drilled hole which gives effect to the penetration of x-ray beam divergence to pass through the base of each hole. This effect will lead to false appearance of image from its original location but it does not being visualized in the radiograph. In this study, a new design of Contrast Detail phantom’s hole which consists of double hole construction has been developed. It can detect the image displacementmore » which is due to off position of anode stem from its original location. The double hole differs from previous milled hole, whereby it consists of combination of different hole diameters. Small hole diameter (3 mm) is positioned on top of larger hole diameter (10 mm). The thickness of double hole acrylic blocks is 13 mm. Result revealed that Multiparameter Double Hole Contrast Detail phantom can visualize the shifted flaw image quality produced by x-ray machine due to improper position of the anode stem which is attached to rotor and stator. The effective focal spot of x-ray beam also has been shifted from the center of collimator as a result of off-position anode stem. As a conclusion, the new design of double hole Contrast Detail phantom able to measure those parameters in a well manner.« less

Endoscopic ultrasound-guided biliary drainage using a newly designed metal stent with a thin delivery system: a preclinical study in phantom and porcine models.

PubMed

Minaga, Kosuke; Kitano, Masayuki; Itonaga, Masahiro; Imai, Hajime; Miyata, Takeshi; Yamao, Kentaro; Tamura, Takashi; Nuta, Junya; Warigaya, Kenji; Kudo, Masatoshi

2017-12-08

This study was designed to evaluate the feasibility and safety of a newly designed self-expandable metal stent for endoscopic ultrasound-guided biliary drainage (EUS-BD) when it was delivered via three different stent delivery systems: a 7.5Fr delivery catheter with a bullet-shaped tip (7.5Fr-bullet), a 7Fr catheter with a bullet-shaped tip (7Fr-bullet), or a 7Fr catheter with a tee-shaped tip (7Fr-tee). This experimental study utilized a porcine model of biliary dilatation involving ten pigs. In the animal study, technical feasibility and clinical outcomes of the stent when placed with each of the delivery systems were examined. In addition, a phantom model was used to measure the resistance of these delivery systems to advancement. Phantom experiments showed that, compared with 7Fr-bullet, 7Fr-tee had less resistance force to the advancement of the stent delivery system. EUS-BD was technically successful in all ten pigs. Fistulous tract dilation was necessary in 100% (2/2), 75% (3/4), and 0% (0/4) of the pigs that underwent EUS-BD using 7.5Fr-bullet, 7Fr-bullet, and 7Fr-tee, respectively. There were no procedure-related complications. Our newly designed metal stent may be feasible and safe for EUS-BD, particularly when delivered by 7Fr-tee, because it eliminates the need for fistulous tract dilation.

Three-dimensional fuse deposition modeling of tissue-simulating phantom for biomedical optical imaging

NASA Astrophysics Data System (ADS)

Dong, Erbao; Zhao, Zuhua; Wang, Minjie; Xie, Yanjun; Li, Shidi; Shao, Pengfei; Cheng, Liuquan; Xu, Ronald X.

2015-12-01

Biomedical optical devices are widely used for clinical detection of various tissue anomalies. However, optical measurements have limited accuracy and traceability, partially owing to the lack of effective calibration methods that simulate the actual tissue conditions. To facilitate standardized calibration and performance evaluation of medical optical devices, we develop a three-dimensional fuse deposition modeling (FDM) technique for freeform fabrication of tissue-simulating phantoms. The FDM system uses transparent gel wax as the base material, titanium dioxide (TiO2) powder as the scattering ingredient, and graphite powder as the absorption ingredient. The ingredients are preheated, mixed, and deposited at the designated ratios layer-by-layer to simulate tissue structural and optical heterogeneities. By printing the sections of human brain model based on magnetic resonance images, we demonstrate the capability for simulating tissue structural heterogeneities. By measuring optical properties of multilayered phantoms and comparing with numerical simulation, we demonstrate the feasibility for simulating tissue optical properties. By creating a rat head phantom with embedded vasculature, we demonstrate the potential for mimicking physiologic processes of a living system.

Experimental verification of a Monte Carlo-based MLC simulation model for IMRT dose calculations in heterogeneous media

NASA Astrophysics Data System (ADS)

Tyagi, N.; Curran, B. H.; Roberson, P. L.; Moran, J. M.; Acosta, E.; Fraass, B. A.

2008-02-01

IMRT often requires delivering small fields which may suffer from electronic disequilibrium effects. The presence of heterogeneities, particularly low-density tissues in patients, complicates such situations. In this study, we report on verification of the DPM MC code for IMRT treatment planning in heterogeneous media, using a previously developed model of the Varian 120-leaf MLC. The purpose of this study is twofold: (a) design a comprehensive list of experiments in heterogeneous media for verification of any dose calculation algorithm and (b) verify our MLC model in these heterogeneous type geometries that mimic an actual patient geometry for IMRT treatment. The measurements have been done using an IMRT head and neck phantom (CIRS phantom) and slab phantom geometries. Verification of the MLC model has been carried out using point doses measured with an A14 slim line (SL) ion chamber inside a tissue-equivalent and a bone-equivalent material using the CIRS phantom. Planar doses using lung and bone equivalent slabs have been measured and compared using EDR films (Kodak, Rochester, NY).

Quantitative PET/CT scanner performance characterization based upon the society of nuclear medicine and molecular imaging clinical trials network oncology clinical simulator phantom.

PubMed

Sunderland, John J; Christian, Paul E

2015-01-01

The Clinical Trials Network (CTN) of the Society of Nuclear Medicine and Molecular Imaging (SNMMI) operates a PET/CT phantom imaging program using the CTN's oncology clinical simulator phantom, designed to validate scanners at sites that wish to participate in oncology clinical trials. Since its inception in 2008, the CTN has collected 406 well-characterized phantom datasets from 237 scanners at 170 imaging sites covering the spectrum of commercially available PET/CT systems. The combined and collated phantom data describe a global profile of quantitative performance and variability of PET/CT data used in both clinical practice and clinical trials. Individual sites filled and imaged the CTN oncology PET phantom according to detailed instructions. Standard clinical reconstructions were requested and submitted. The phantom itself contains uniform regions suitable for scanner calibration assessment, lung fields, and 6 hot spheric lesions with diameters ranging from 7 to 20 mm at a 4:1 contrast ratio with primary background. The CTN Phantom Imaging Core evaluated the quality of the phantom fill and imaging and measured background standardized uptake values to assess scanner calibration and maximum standardized uptake values of all 6 lesions to review quantitative performance. Scanner make-and-model-specific measurements were pooled and then subdivided by reconstruction to create scanner-specific quantitative profiles. Different makes and models of scanners predictably demonstrated different quantitative performance profiles including, in some cases, small calibration bias. Differences in site-specific reconstruction parameters increased the quantitative variability among similar scanners, with postreconstruction smoothing filters being the most influential parameter. Quantitative assessment of this intrascanner variability over this large collection of phantom data gives, for the first time, estimates of reconstruction variance introduced into trials from allowing trial sites to use their preferred reconstruction methodologies. Predictably, time-of-flight-enabled scanners exhibited less size-based partial-volume bias than non-time-of-flight scanners. The CTN scanner validation experience over the past 5 y has generated a rich, well-curated phantom dataset from which PET/CT make-and-model and reconstruction-dependent quantitative behaviors were characterized for the purposes of understanding and estimating scanner-based variances in clinical trials. These results should make it possible to identify and recommend make-and-model-specific reconstruction strategies to minimize measurement variability in cancer clinical trials. © 2015 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

Scatter correction method for x-ray CT using primary modulation: Phantom studies

PubMed Central

Gao, Hewei; Fahrig, Rebecca; Bennett, N. Robert; Sun, Mingshan; Star-Lack, Josh; Zhu, Lei

2010-01-01

Purpose: Scatter correction is a major challenge in x-ray imaging using large area detectors. Recently, the authors proposed a promising scatter correction method for x-ray computed tomography (CT) using primary modulation. Proof of concept was previously illustrated by Monte Carlo simulations and physical experiments on a small phantom with a simple geometry. In this work, the authors provide a quantitative evaluation of the primary modulation technique and demonstrate its performance in applications where scatter correction is more challenging. Methods: The authors first analyze the potential errors of the estimated scatter in the primary modulation method. On two tabletop CT systems, the method is investigated using three phantoms: A Catphan©600 phantom, an anthropomorphic chest phantom, and the Catphan©600 phantom with two annuli. Two different primary modulators are also designed to show the impact of the modulator parameters on the scatter correction efficiency. The first is an aluminum modulator with a weak modulation and a low modulation frequency, and the second is a copper modulator with a strong modulation and a high modulation frequency. Results: On the Catphan©600 phantom in the first study, the method reduces the error of the CT number in the selected regions of interest (ROIs) from 371.4 to 21.9 Hounsfield units (HU); the contrast to noise ratio also increases from 10.9 to 19.2. On the anthropomorphic chest phantom in the second study, which represents a more difficult case due to the high scatter signals and object heterogeneity, the method reduces the error of the CT number from 327 to 19 HU in the selected ROIs and from 31.4% to 5.7% on the overall average. The third study is to investigate the impact of object size on the efficiency of our method. The scatter-to-primary ratio estimation error on the Catphan©600 phantom without any annulus (20 cm in diameter) is at the level of 0.04, it rises to 0.07 and 0.1 on the phantom with an elliptical annulus (30 cm in the minor axis and 38 cm in the major axis) and with a circular annulus (38 cm in diameter). Conclusions: On the three phantom studies, good scatter correction performance of the proposed method has been demonstrated using both image comparisons and quantitative analysis. The theory and experiments demonstrate that a strong primary modulation that possesses a low transmission factor and a high modulation frequency is preferred for high scatter correction accuracy. PMID:20229902

National Dam Safety Program. Hunter Dam (MO 10029), Mississippi - Kaskaskia - St. Louis Basin, St. Louis County, Missouri. Phase I Inspection Report.

DTIC Science & Technology

1978-06-01

EDTION oF I NOV6S IS oBSOLETE EJUN I UNCLASSIFIED SECuRiITY CLASSIICATION OF THIS PAGE (Whon Datai Entered) SECURtITY CLASSIFICATION OF THIS PAO9(Whou...moveable. Since the watershed area is essentially one- third square mile with a time of concentration of flows substantially less than an hour, no

Dawn Spacecraft Processing

NASA Image and Video Library

2007-04-10

In Astrotech's Payload Processing Facility, technicians help secure the Dawn spacecraft onto a moveable stand. Dawn will be moved into clean room C for unbagging and further processing. Dawn's mission is to explore two of the asteroid belt's most intriguing and dissimilar occupants: asteroid Vesta and the dwarf planet Ceres. The Dawn mission is managed by JPL, a division of the California Institute of Technology in Pasadena, for NASA's Science Mission Directorate in Washington, D.C.

Optimizing the acquisition geometry for digital breast tomosynthesis using the Defrise phantom

NASA Astrophysics Data System (ADS)

Acciavatti, Raymond J.; Chang, Alice; Woodbridge, Laura; Maidment, Andrew D. A.

2014-03-01

In cone beam computed tomography (CT), it is common practice to use the Defrise phantom for image quality assessment. The phantom consists of a stack of plastic plates with low frequency spacing. Because the x-ray beam may traverse multiple plates, the spacing between plates can appear blurry in the reconstruction, and hence modulation provides a measure of image quality. This study considers the potential merit of using the Defrise phantom in digital breast tomosynthesis (DBT), a modality with a smaller projection range than CT. To this end, a Defrise phantom was constructed and subsequently imaged with a commercial DBT system. It was demonstrated that modulation is dependent on position and orientation in the reconstruction. Modulation is preserved over a broad range of positions along the chest wall if the input frequency is oriented in the tube travel direction. By contrast, modulation is degraded with increasing distance from the chest wall if the input frequency is oriented in the posteroanterior (PA) direction. A theoretical framework was then developed to model these results. Reconstructions were calculated in an acquisition geometry designed to improve modulation. Unlike current geometries in which the x-ray tube motion is restricted to the plane of the chest wall, we consider a geometry with an additional component of tube motion along the PA direction. In simulations, it is shown that the newly proposed geometry improves modulation at positions distal to the chest wall. In conclusion, this study demonstrates that the Defrise phantom is a tool for optimizing DBT systems.

Multilayered phantoms with tunable optical properties for a better understanding of light/tissue interactions

NASA Astrophysics Data System (ADS)

Roig, Blandine; Koenig, Anne; Perraut, François; Piot, Olivier; Vignoud, Séverine; Lavaud, Jonathan; Manfait, Michel; Dinten, Jean-Marc

2015-03-01

Light/tissue interactions, like diffuse reflectance, endogenous fluorescence and Raman scattering, are a powerful means for providing skin diagnosis. Instrument calibration is an important step. We thus developed multilayered phantoms for calibration of optical systems. These phantoms mimic the optical properties of biological tissues such as skin. Our final objective is to better understand light/tissue interactions especially in the case of confocal Raman spectroscopy. The phantom preparation procedure is described, including the employed method to obtain a stratified object. PDMS was chosen as the bulk material. TiO2 was used as light scattering agent. Dye and ink were adopted to mimic, respectively, oxy-hemoglobin and melanin absorption spectra. By varying the amount of the incorporated components, we created a material with tunable optical properties. Monolayer and multilayered phantoms were designed to allow several characterization methods. Among them, we can name: X-ray tomography for structural information; Diffuse Reflectance Spectroscopy (DRS) with a homemade fibered bundle system for optical characterization; and Raman depth profiling with a commercial confocal Raman microscope for structural information and for our final objective. For each technique, the obtained results are presented and correlated when possible. A few words are said on our final objective. Raman depth profiles of the multilayered phantoms are distorted by elastic scattering. The signal attenuation through each single layer is directly dependent on its own scattering property. Therefore, determining the optical properties, obtained here with DRS, is crucial to properly correct Raman depth profiles. Thus, it would be permitted to consider quantitative studies on skin for drug permeation follow-up or hydration assessment, for instance.

Magnetic resonance imaging properties of multimodality anthropomorphic silicone rubber phantoms for validating surgical robots and image guided therapy systems

NASA Astrophysics Data System (ADS)

Cheung, Carling L.; Looi, Thomas; Drake, James; Kim, Peter C. W.

2012-02-01

The development of image guided robotic and mechatronic platforms for medical applications requires a phantom model for initial testing. Finding an appropriate phantom becomes challenging when the targeted patient population is pediatrics, particularly infants, neonates or fetuses. Our group is currently developing a pediatricsized surgical robot that operates under fused MRI and laparoscopic video guidance. To support this work, we describe a method for designing and manufacturing silicone rubber organ phantoms for the purpose of testing the robotics and the image fusion system. A surface model of the organ is obtained and converted into a mold that is then rapid-prototyped using a 3D printer. The mold is filled with a solution containing a particular ratio of silicone rubber to slacker additive to achieve a specific set of tactile and imaging characteristics in the phantom. The expected MRI relaxation times of different ratios of silicone rubber to slacker additive are experimentally quantified so that the imaging properties of the phantom can be matched to those of the organ that it represents. Samples of silicone rubber and slacker additive mixed in ratios ranging from 1:0 to 1:1.5 were prepared and scanned using inversion recovery and spin echo sequences with varying TI and TE, respectively, in order to fit curves to calculate the expected T1 and T2 relaxation times of each ratio. A set of infantsized abdominal organs was prepared, which were successfully sutured by the robot and imaged using different modalities.

Development of anatomically and dielectrically accurate breast phantoms for microwave imaging applications

NASA Astrophysics Data System (ADS)

O'Halloran, M.; Lohfeld, S.; Ruvio, G.; Browne, J.; Krewer, F.; Ribeiro, C. O.; Inacio Pita, V. C.; Conceicao, R. C.; Jones, E.; Glavin, M.

2014-05-01

Breast cancer is one of the most common cancers in women. In the United States alone, it accounts for 31% of new cancer cases, and is second only to lung cancer as the leading cause of deaths in American women. More than 184,000 new cases of breast cancer are diagnosed each year resulting in approximately 41,000 deaths. Early detection and intervention is one of the most significant factors in improving the survival rates and quality of life experienced by breast cancer sufferers, since this is the time when treatment is most effective. One of the most promising breast imaging modalities is microwave imaging. The physical basis of active microwave imaging is the dielectric contrast between normal and malignant breast tissue that exists at microwave frequencies. The dielectric contrast is mainly due to the increased water content present in the cancerous tissue. Microwave imaging is non-ionizing, does not require breast compression, is less invasive than X-ray mammography, and is potentially low cost. While several prototype microwave breast imaging systems are currently in various stages of development, the design and fabrication of anatomically and dielectrically representative breast phantoms to evaluate these systems is often problematic. While some existing phantoms are composed of dielectrically representative materials, they rarely accurately represent the shape and size of a typical breast. Conversely, several phantoms have been developed to accurately model the shape of the human breast, but have inappropriate dielectric properties. This study will brie y review existing phantoms before describing the development of a more accurate and practical breast phantom for the evaluation of microwave breast imaging systems.

A Semi-flexible 64-channel Receive-only Phased Array for Pediatric Body MRI at 3T

PubMed Central

Zhang, Tao; Grafendorfer, Thomas; Cheng, Joseph Y.; Ning, Peigang; Rainey, Bob; Giancola, Mark; Ortman, Sarah; Robb, Fraser J.; Calderon, Paul D.; Hargreaves, Brian A.; Lustig, Michael; Scott, Greig C.; Pauly, John M.; Vasanawala, Shreyas S.

2015-01-01

Purpose To design, construct, and validate a semi-flexible 64-channel receive-only phased array for pediatric body MRI at 3T. Methods A 64-channel receive-only phased array was developed and constructed. The designed flexible coil can easily conform to different patient sizes with non-overlapping coil elements in the transverse plane. It can cover a field of view of up to 44 × 28 cm2 and removes the need for coil repositioning for body MRI patients with multiple clinical concerns. The 64-channel coil was compared with a 32-channel standard coil for signal-to-noise ratio (SNR) and parallel imaging performances on different phantoms. With IRB approval and informed consent/assent, the designed coil was validated on 21 consecutive pediatric patients. Results The pediatric coil provided higher SNR than the standard coil on different phantoms, with the averaged SNR gain at least 23% over a depth of 7 cm along the cross-section of phantoms. It also achieved better parallel imaging performance under moderate acceleration factors. Good image quality (average score 4.6 out of 5) was achieved using the developed pediatric coil in the clinical studies. Conclusion A 64-channel semi-flexible receive-only phased array has been developed and validated to facilitate high quality pediatric body MRI at 3T. PMID:26418283

Design of an optical system for interrogation of implanted luminescent sensors and verification with silicone skin phantoms.

PubMed

Long, Ruiqi; McShane, Mike

2012-09-01

Implantable luminescent sensors are being developed for on-demand monitoring of blood glucose levels. For these sensors to be deployed in vivo, a matched external hardware system is needed. In this paper, we designed a compact, low-cost optical system with highly efficient photon delivery and collection using advanced optical modeling software. Compared to interrogation with a fiber bundle, the new system was predicted to improve interrogation efficiency by a factor of 200 for native sensors; an improvement of 37 times was predicted for sensors implanted at a depth of 1 mm in a skin-simulating phantom. A physical prototype was tested using silicone-based skin phantoms developed specifically to mimic the scattering and absorbing properties of human skin. The experimental evaluations revealed that the prototype device performed in agreement with expectations from simulation results, resulting in an overall improvement of over 2000 times. This efficient system enables use of a low-cost commercial spectrometer for recording sensor emission, which was not possible using only fiber optic delivery and collection, and will be used as a tool for in vivo studies with animal models or human subjects.

Experimental evaluation of the thermal properties of two tissue equivalent phantom materials.

PubMed

Craciunescu, O I; Howle, L E; Clegg, S T

1999-01-01

Tissue equivalent radio frequency (RF) phantoms provide a means for measuring the power deposition of various hyperthermia therapy applicators. Temperature measurements made in phantoms are used to verify the accuracy of various numerical approaches for computing the power and/or temperature distributions. For the numerical simulations to be accurate, the electrical and thermal properties of the materials that form the phantom should be accurately characterized. This paper reports on the experimentally measured thermal properties of two commonly used phantom materials, i.e. a rigid material with the electrical properties of human fat, and a low concentration polymer gel with the electrical properties of human muscle. Particularities of the two samples required the design of alternative measuring techniques for the specific heat and thermal conductivity. For the specific heat, a calorimeter method is used. For the thermal diffusivity, a method derived from the standard guarded comparative-longitudinal heat flow technique was used for both materials. For the 'muscle'-like material, the thermal conductivity, density and specific heat at constant pressure were measured as: k = 0.31 +/- 0.001 W(mK)(-1), p = 1026 +/- 7 kgm(-3), and c(p) = 4584 +/- 107 J(kgK)(-1). For the 'fat'-like material, the literature reports on the density and specific heat such that only the thermal conductivity was measured as k = 0.55 W(mK)(-1).

HOME-BASED SELF-DELIVERED MIRROR THERAPY FOR PHANTOM PAIN: A PILOT STUDY*

PubMed Central

Darnall, Beth D.; Li, Hong

2014-01-01

Objective To test the feasibility and preliminary efficacy of self-delivered home-based mirror therapy for phantom pain. Design Uncontrolled prospective treatment outcome pilot study. Participants Forty community-dwelling adults with unilateral amputation and phantom pain >3 on a 0–10 numeric rating scale enrolled either during a one-time study visit (n = 30) or remotely (n = 10). Methods Participants received an explanation of mirror therapy and were asked to self-treat for 25 min daily. Participants completed and posted back sets of outcomes questionnaires at months 1 and 2 post-treatment. Main outcome was mean phantom pain intensity at post-treatment. Results A significant reduction in mean phantom pain intensity was found at month 1 (n = 31, p = 0.0002) and at month 2 (n = 26, p = 0.002). The overall median percentage reduction at month 2 was 15.4%. Subjects with high education (>16 years) compared with low education (<16 years) (37.5% vs 4.1%) had greater reduction in pain intensity (p = 0.01). Conclusion These findings support the feasibility and efficacy of home-based self-delivered mirror therapy; this low-cost treatment may defray medical costs, therapy visits, and the patient travel burden for people with motivation and a high level of education. More research is needed to determine methods of cost-effective support for people with lower levels of education. PMID:22378591

Development and validation of segmentation and interpolation techniques in sinograms for metal artifact suppression in CT.

PubMed

Veldkamp, Wouter J H; Joemai, Raoul M S; van der Molen, Aart J; Geleijns, Jacob

2010-02-01

Metal prostheses cause artifacts in computed tomography (CT) images. The purpose of this work was to design an efficient and accurate metal segmentation in raw data to achieve artifact suppression and to improve CT image quality for patients with metal hip or shoulder prostheses. The artifact suppression technique incorporates two steps: metal object segmentation in raw data and replacement of the segmented region by new values using an interpolation scheme, followed by addition of the scaled metal signal intensity. Segmentation of metal is performed directly in sinograms, making it efficient and different from current methods that perform segmentation in reconstructed images in combination with Radon transformations. Metal signal segmentation is achieved by using a Markov random field model (MRF). Three interpolation methods are applied and investigated. To provide a proof of concept, CT data of five patients with metal implants were included in the study, as well as CT data of a PMMA phantom with Teflon, PVC, and titanium inserts. Accuracy was determined quantitatively by comparing mean Hounsfield (HU) values and standard deviation (SD) as a measure of distortion in phantom images with titanium (original and suppressed) and without titanium insert. Qualitative improvement was assessed by comparing uncorrected clinical images with artifact suppressed images. Artifacts in CT data of a phantom and five patients were automatically suppressed. The general visibility of structures clearly improved. In phantom images, the technique showed reduced SD close to the SD for the case where titanium was not inserted, indicating improved image quality. HU values in corrected images were different from expected values for all interpolation methods. Subtle differences between interpolation methods were found. The new artifact suppression design is efficient, for instance, in terms of preserving spatial resolution, as it is applied directly to original raw data. It successfully reduced artifacts in CT images of five patients and in phantom images. Sophisticated interpolation methods are needed to obtain reliable HU values close to the prosthesis.

A simplified approach for exit dose in vivo measurements in radiotherapy and its clinical application.

PubMed

Banjade, D P; Shrestha, S L; Shukri, A; Tajuddin, A A; Bhat, M

2002-09-01

This is a study using LiF:Mg;Ti thermoluminescent dosimeter (TLD) rods in phantoms to investigate the effect of lack of backscatter on exit dose. Comparing the measured dose with anticipated dose calculated using tissue maximum ratio (TMR) or percentage depth dose (PDD) gives rise to a correction factor. This correction factor may be applied to in-vivo dosimetry results to derive true dose to a point within the patient. Measurements in a specially designed humanoid breast phantom as well as patients undergoing radiotherapy treatment were also been done. TLDs with reproducibility of within +/- 3% (1 SD) are irradiated in a series of measurements for 6 and 10 MV photon beams from a medical linear accelerator. The measured exit doses for the different phantom thickness for 6 MV beams are found to be lowered by 10.9 to 14.0% compared to the dose derived from theoretical estimation (normalized dose at dmax). The same measurements for 10 MV beams are lowered by 9.0 to 13.5%. The variations of measured exit dose for different field sizes are found to be within 2.5%. The exit doses with added backscatter material from 2 mm up to 15 cm, shows gradual increase and the saturated values agreed within 1.5% with the expected results for both beams. The measured exit doses in humanoid breast phantom as well as in the clinical trial on patients undergoing radiotherapy also agreed with the predicted results based on phantom measurements. The authors' viewpoint is that this technique provides sufficient information to design exit surface bolus to restore build down effect in cases where part of the exit surface is being considered as a target volume. It indicates that the technique could be translated for in vivo dose measurements, which may be a conspicuous step of quality assurance in clinical practice.

A fast and reliable method for daily quality assurance in spot scanning proton therapy with a compact and inexpensive phantom.

PubMed

Bizzocchi, Nicola; Fracchiolla, Francesco; Schwarz, Marco; Algranati, Carlo

2017-01-01

In a radiotherapy center, daily quality assurance (QA) measurements are performed to ensure that the equipment can be safely used for patient treatment on that day. In a pencil beam scanning (PBS) proton therapy center, spot positioning, spot size, range, and dose output are usually verified every day before treatments. We designed, built, and tested a new, reliable, sensitive, and inexpensive phantom, coupled with an array of ionization chambers, for daily QA that reduces the execution times while preserving the reliability of the test. The phantom is provided with 2 pairs of wedges to sample the Bragg peak at different depths to have a transposition on the transverse plane of the depth dose. Three "boxes" are used to check spot positioning and delivered dose. The box thickness helps spread the single spot and to fit a Gaussian profile on a low resolution detector. We tested whether our new QA solution could detect errors larger than our action levels: 1 mm in spot positioning, 2 mm in range, and 10% in spot size. Execution time was also investigated. Our method is able to correctly detect 98% of spots that are actually in tolerance for spot positioning and 99% of spots out of 1 mm tolerance. All range variations greater than the threshold (2 mm) were correctly detected. The analysis performed over 1 month showed a very good repeatability of spot characteristics. The time taken to perform the daily quality assurance is 20 minutes, a half of the execution time of the former multidevice procedure. This "in-house build" phantom substitutes 2 very expensive detectors (a multilayer ionization chamber [MLIC] and a strip chamber, reducing by 5 times the cost of the equipment. We designed, built, and validated a phantom that allows for accurate, sensitive, fast, and inexpensive daily QA procedures in proton therapy with PBS. Copyright © 2017 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

Collimator Design for a Brain SPECT/MRI Insert

NASA Astrophysics Data System (ADS)

Salvado, Debora; Erlandsson, Kjell; Bousse, Alexandre; Occhipinti, Michele; Busca, Paolo; Fiorini, Carlo; Hutton, Brian F.

2015-08-01

This project's goal is to design a SPECT insert for a clinical MRI system for simultaneous brain SPECT/MR imaging, with a high-sensitivity collimator and high-resolution detectors. We have compared eight collimator designs, four multi-pinhole and four multi-slit slit-slat configurations. The collimation was designed for a system with 2 rings of 25 5 × 5 cm detectors. We introduce the concept of 1/2-pinhole and 1/2-slit, which are transaxially shared between two adjacent detectors. Analytical geometric efficiency was calculated for an activity distribution corresponding to a human brain and a range of intrinsic detector resolutions Ri and target resolutions Rt at the centre of the FOV. Noise-free data were simulated with and without depth-of-interaction (DOI) information, 0.8 mm Ri and 10 mm Rt FWHM, and reconstructed for uniform, Defrise, Derenzo, and Zubal brain phantoms. Comparing the multi-pinhole and multi-slit slit-slat collimators, the former gives better reconstructed uniformity and transaxial resolution, while the latter gives better axial resolution. Although the 2 ×2-pinhole and 2-slit designs give the highest sensitivities, they result in a sub-optimal utilisation of the detector FOV. The best options are therefore the 5+ 2 1/2-pinhole and the 1 + 2 1/2-slit systems, with sensitivities of 1.8 ×10-4 and 3.2 ×10-4, respectively. Noiseless brain phantom reconstructions with the multi-pinhole collimator are slightly superior as compared to slit-slat, in terms of symmetry and accuracy of the activity distribution, but the same is not true when noise is included. DOI information reduces artefacts and improves uniformity in geometric phantoms. Further evaluation is needed with prototype collimators.

Design and characterisation of miniaturised cavity-backed patch antenna for microwave hyperthermia.

PubMed

Chakaravarthi, Geetha; Arunachalam, Kavitha

2015-01-01

The aim of this study was to describe the design and characterisation of a miniaturised 434 MHz patch antenna enclosed in a metal cavity for microwave hyperthermia treatment of cancer. Electromagnetic (EM) field distribution in the near field of a microstrip patch irradiating body tissue was studied using finite element method (FEM) simulations. Antenna miniaturisation was achieved through dielectric loading with very high permittivity, metal enclosure, patch folding and shorting post. Frequency dependent electrical properties of materials were incorporated wherever appropriate using dispersion model and measurements. Antenna return loss and specific absorption rate (SAR) at 434 MHz were measured on muscle phantoms for characterisation. The design was progressively optimised to yield a compact 434 MHz patch (22 mm × 8.8 mm × 10 mm) inside a metal cavity (40 mm × 12 mm) with integrated coupling water bolus (35 mm). The fabricated antenna with integrated water bolus was self resonant at 434 MHz without load, and has better than -10 dB return loss (S11) with 13-20 MHz bandwidth on two different phantoms. SAR at 434 MHz measured using an infrared (IR) thermal camera on split phantoms indicated penetration depth for -3 dB SAR as 8.25 mm compared to 8.87 mm for simulation. The simulated and measured SAR coverage along phantom depth was 3.09 cm(2) and 3.21 cm(2) respectively at -3 dB, and 6.42 cm(2) and 9.07 cm(2) respectively at -6 dB. SAR full width at half maximum (FWHM) at 5 mm and 20 mm depths were 54.68 mm and 51.18 mm respectively in simulation, and 49.47 mm and 43.75 mm respectively in experiments. Performance comparison of the cavity-backed patch indicates more than 89% co-polarisation and higher directivity which resulted in deeper penetration compared to the patch applicators of similar or larger size proposed for hyperthermia treatment of cancer. The fabricated cavity-backed applicator is self-resonant at 434 MHz with a negligible shift in resonance when coupled to different phantoms, Δf/f0 less than 1.16%. IR thermography-based SAR measurements indicated that the -3 dB SAR of the cavity-backed aperture antenna covered the radiating aperture surface at 5 mm and 20 mm depths. It can be concluded that the compact cavity-backed patch antenna has stable resonance, higher directivity and low cross polarisation, and is suitable for design of microwave hyperthermia array applicators with adjustable heating pattern for superficial and/or deep tissue heating.

A tritium activity monitor for the KATRIN Experiment

NASA Astrophysics Data System (ADS)

Schmitt, Udo

2008-06-01

The KArlsruhe TRItium Neutrino experiment KATRIN is designed to measure the absolute neutrino mass scale by analyzing the endpoint region of the tritium beta-decay spectrum with a sensitivity of 0.2 eV/c2 (90 % C.L.). A high-luminous windowless gaseous tritium source with an activity of 1.7 · 1011 Bq will produce the decay electrons, their energy spectrum will be analyzed by a combination of two electrostatic retarding spectrometers with magnetic adiabatic collimation (MAC-E-filter). Fluctuations of the source column density and inelastic scattering processes within the source affect the energy distribution of the decay electrons. Hence, a precise and continuous monitoring of the source activity is necessary to correct the data taken by the main detector. A prototype of the beam monitor detector, based on a silicon drift diode, has been developed to measure an expected counting rate in the range of 106/(s · mm2). The detector element shall be moveable across the complete beam in a magnetic field of 0.8 T, resulting in a beam diameter of 20 cm. A precise sensor positioning device has been designed and built to be compatible with the primary beamline vacuum of 10-11 mbar.

Four-dimensional dose reconstruction through in vivo phase matching of cine images of electronic portal imaging device

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yoon, Jihyung; Jung, Jae Won, E-mail: jungj@ecu.ed

Purpose: A method is proposed to reconstruct a four-dimensional (4D) dose distribution using phase matching of measured cine images to precalculated images of electronic portal imaging device (EPID). Methods: (1) A phantom, designed to simulate a tumor in lung (a polystyrene block with a 3 cm diameter embedded in cork), was placed on a sinusoidally moving platform with an amplitude of 1 cm and a period of 4 s. Ten-phase 4D computed tomography (CT) images of the phantom were acquired. A planning target volume (PTV) was created by adding a margin of 1 cm around the internal target volume ofmore » the tumor. (2) Three beams were designed, which included a static beam, a theoretical dynamic beam, and a planning-optimized dynamic beam (PODB). While the theoretical beam was made by manually programming a simplistic sliding leaf motion, the planning-optimized beam was obtained from treatment planning. From the three beams, three-dimensional (3D) doses on the phantom were calculated; 4D dose was calculated by means of the ten phase images (integrated over phases afterward); serving as “reference” images, phase-specific EPID dose images under the lung phantom were also calculated for each of the ten phases. (3) Cine EPID images were acquired while the beams were irradiated to the moving phantom. (4) Each cine image was phase-matched to a phase-specific CT image at which common irradiation occurred by intercomparing the cine image with the reference images. (5) Each cine image was used to reconstruct dose in the phase-matched CT image, and the reconstructed doses were summed over all phases. (6) The summation was compared with forwardly calculated 4D and 3D dose distributions. Accounting for realistic situations, intratreatment breathing irregularity was simulated by assuming an amplitude of 0.5 cm for the phantom during a portion of breathing trace in which the phase matching could not be performed. Intertreatment breathing irregularity between the time of treatment and the time of planning CT was considered by utilizing the same reduced amplitude when the phantom was irradiated. To examine the phase matching in a humanoid environment, the matching was also performed in a digital phantom (4D XCAT phantom). Results: For the static, the theoretical, and the planning-optimized dynamic beams, the 4D reconstructed doses showed agreement with the forwardly calculated 4D doses within the gamma pass rates of 92.7%, 100%, and 98.1%, respectively, at the isocenter plane given by 3%/3 mm criteria. Excellent agreement in dose volume histogram of PTV and lung-PTV was also found between the two 4D doses, while substantial differences were found between the 3D and the 4D doses. The significant breathing irregularities modeled in this study were found not to be noticeably affecting the reconstructed dose. The phase matching was performed equally well in a digital phantom. Conclusions: The method of retrospective phase determination of a moving object under irradiation provided successful 4D dose reconstruction. This method will provide accurate quality assurance and facilitate adaptive therapy when distinguishable objects such as well-defined tumors, diaphragm, and organs with markers (pancreas and liver) are covered by treatment beam apertures.« less

Four-dimensional dose reconstruction through in vivo phase matching of cine images of electronic portal imaging device.

PubMed

Yoon, Jihyung; Jung, Jae Won; Kim, Jong Oh; Yi, Byong Yong; Yeo, Inhwan

2016-07-01

A method is proposed to reconstruct a four-dimensional (4D) dose distribution using phase matching of measured cine images to precalculated images of electronic portal imaging device (EPID). (1) A phantom, designed to simulate a tumor in lung (a polystyrene block with a 3 cm diameter embedded in cork), was placed on a sinusoidally moving platform with an amplitude of 1 cm and a period of 4 s. Ten-phase 4D computed tomography (CT) images of the phantom were acquired. A planning target volume (PTV) was created by adding a margin of 1 cm around the internal target volume of the tumor. (2) Three beams were designed, which included a static beam, a theoretical dynamic beam, and a planning-optimized dynamic beam (PODB). While the theoretical beam was made by manually programming a simplistic sliding leaf motion, the planning-optimized beam was obtained from treatment planning. From the three beams, three-dimensional (3D) doses on the phantom were calculated; 4D dose was calculated by means of the ten phase images (integrated over phases afterward); serving as "reference" images, phase-specific EPID dose images under the lung phantom were also calculated for each of the ten phases. (3) Cine EPID images were acquired while the beams were irradiated to the moving phantom. (4) Each cine image was phase-matched to a phase-specific CT image at which common irradiation occurred by intercomparing the cine image with the reference images. (5) Each cine image was used to reconstruct dose in the phase-matched CT image, and the reconstructed doses were summed over all phases. (6) The summation was compared with forwardly calculated 4D and 3D dose distributions. Accounting for realistic situations, intratreatment breathing irregularity was simulated by assuming an amplitude of 0.5 cm for the phantom during a portion of breathing trace in which the phase matching could not be performed. Intertreatment breathing irregularity between the time of treatment and the time of planning CT was considered by utilizing the same reduced amplitude when the phantom was irradiated. To examine the phase matching in a humanoid environment, the matching was also performed in a digital phantom (4D XCAT phantom). For the static, the theoretical, and the planning-optimized dynamic beams, the 4D reconstructed doses showed agreement with the forwardly calculated 4D doses within the gamma pass rates of 92.7%, 100%, and 98.1%, respectively, at the isocenter plane given by 3%/3 mm criteria. Excellent agreement in dose volume histogram of PTV and lung-PTV was also found between the two 4D doses, while substantial differences were found between the 3D and the 4D doses. The significant breathing irregularities modeled in this study were found not to be noticeably affecting the reconstructed dose. The phase matching was performed equally well in a digital phantom. The method of retrospective phase determination of a moving object under irradiation provided successful 4D dose reconstruction. This method will provide accurate quality assurance and facilitate adaptive therapy when distinguishable objects such as well-defined tumors, diaphragm, and organs with markers (pancreas and liver) are covered by treatment beam apertures.

Corrosion-Mitigating, Bondable, Fluorinated Barrier Coating for Anodized Magnesium

DTIC Science & Technology

2016-05-01

transport the precursor vapor throughout the study was set at 9,500 sccm. The setup also incorporated a 38- × 54- × 0.6-cm stainless steel moveable...evaporated and that silane crosslinking had occurred, samples were allowed to sit uncovered in a fume hood for 1 h prior to electrochemical...measurement, contact-angle measurement, or plasma treatment. Samples were stored in a fume hood for approximately 24 h before applying an epoxy topcoat

Design of a Model of Forearm Bone Fractures for Educational Purposes

ERIC Educational Resources Information Center

Jastaniah, Saddig; Hamdan, Abdulrahman; Alhadrami, Abdullah; Almatrafi, Talal; Arif, Ahmed; Almalki, Hassan

2016-01-01

This work explores a new approach to demonstrate possible forearm fractures in humans as an educating means for student radiographers. The Design of abnormal bones are not normally available as phantoms; the manufacturer usually produces normal human musculoskeletal models for educational purposes. Hence fractures and abnormalities are usually…

SU-F-T-667: Development and Validation of Dose Calculation for An Open-Source KV Treatment Planning System for Small Animal Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prajapati, S; Mo, X; Bednarz, B

Purpose: An open-source, convolution/superposition based kV-treatment planning system(TPS) was developed for small animal radiotherapy from previously existed in-house MV-TPS. It is flexible and applicable to both step and shoot and helical tomotherapy treatment delivery. For initial commissioning process, the dose calculation from kV-TPS was compared with measurements and Monte Carlo(MC) simulations. Methods: High resolution, low energy kernels were simulated using EGSnrc user code EDKnrc, which was used as an input in kV-TPS together with MC-simulated x-ray beam spectrum. The Blue Water™ homogeneous phantom (with film inserts) and heterogeneous phantom (with film and TLD inserts) were fabricated. Phantom was placed atmore » 100cm SSD, and was irradiated with 250 kVp beam for 10mins with 1.1cm × 1.1cm open field (at 100cm) created by newly designed binary micro-MLC assembly positioned at 90cm SSD. Gafchromic™ EBT3 film was calibrated in-phantom following AAPM TG-61 guidelines, and were used for measurement at 5 different depths in phantom. Calibrated TLD-100s were obtained from ADCL. EGS and MNCP5 simulation were used to model experimental irradiation set up calculation of dose in phantom. Results: Using the homogeneous phantom, dose difference between film and kV-TPS was calculated: mean(x)=0.9%; maximum difference(MD)=3.1%; standard deviation(σ)=1.1%. Dose difference between MCNP5 and kV-TPS was: x=1.5%; MD=4.6%; σ=1.9%. Dose difference between EGS and kV-TPS was: x=0.8%; MD=1.9%; σ=0.8%. Using the heterogeneous phantom, dose difference between film and kV-TPS was: x=2.6%; MD=3%; σ=1.1%; and dose difference between TLD and kV-TPS was: x=2.9%; MD=6.4%; σ=2.5%. Conclusion: The inhouse, open-source kV-TPS dose calculation system was comparable within 5% of measurements and MC simulations in both homogeneous and heterogeneous phantoms. The dose calculation system of the kV-TPS is validated as a part of initial commissioning process for small animal radiotherapy. The kV-TPS has the potential for accurate dose calculation for any kV treatment or imaging modalities.« less

Development of a dual-energy computed tomography quality control program: Characterization of scanner response and definition of relevant parameters for a fast-kVp switching dual-energy computed tomography system.

PubMed

Nute, Jessica L; Jacobsen, Megan C; Stefan, Wolfgang; Wei, Wei; Cody, Dianna D

2018-04-01

A prototype QC phantom system and analysis process were developed to characterize the spectral capabilities of a fast kV-switching dual-energy computed tomography (DECT) scanner. This work addresses the current lack of quantitative oversight for this technology, with the goal of identifying relevant scan parameters and test metrics instrumental to the development of a dual-energy quality control (DEQC). A prototype elliptical phantom (effective diameter: 35 cm) was designed with multiple material inserts for DECT imaging. Inserts included tissue equivalent and material rods (including iodine and calcium at varying concentrations). The phantom was scanned on a fast kV-switching DECT system using 16 dual-energy acquisitions (CTDIvol range: 10.3-62 mGy) with varying pitch, rotation time, and tube current. The circular head phantom (22 cm diameter) was scanned using a similar protocol (12 acquisitions; CTDIvol range: 36.7-132.6 mGy). All acquisitions were reconstructed at 50, 70, 110, and 140 keV and using a water-iodine material basis pair. The images were evaluated for iodine quantification accuracy, stability of monoenergetic reconstruction CT number, noise, and positional constancy. Variance component analysis was used to identify technique parameters that drove deviations in test metrics. Variances were compared to thresholds derived from manufacturer tolerances to determine technique parameters that had a nominally significant effect on test metrics. Iodine quantification error was largely unaffected by any of the technique parameters investigated. Monoenergetic HU stability was found to be affected by mAs, with a threshold under which spectral separation was unsuccessful, diminishing the utility of DECT imaging. Noise was found to be affected by CTDIvol in the DEQC body phantom, and CTDIvol and mA in the DEQC head phantom. Positional constancy was found to be affected by mAs in the DEQC body phantom and mA in the DEQC head phantom. A streamlined scan protocol was developed to further investigate the effects of CTDIvol and rotation time while limiting data collection to the DEQC body phantom. Further data collection will be pursued to determine baseline values and statistically based failure thresholds for the validation of long-term DECT scanner performance. © 2018 American Association of Physicists in Medicine.

Engineering and performance (NEMA and animal) of a lower-cost higher-resolution animal PET/CT scanner using photomultiplier-quadrant-sharing detectors.

PubMed

Wong, Wai-Hoi; Li, Hongdi; Baghaei, Hossain; Zhang, Yuxuan; Ramirez, Rocio A; Liu, Shitao; Wang, Chao; An, Shaohui

2012-11-01

The dedicated murine PET (MuPET) scanner is a high-resolution, high-sensitivity, and low-cost preclinical PET camera designed and manufactured at our laboratory. In this article, we report its performance according to the NU 4-2008 standards of the National Electrical Manufacturers Association (NEMA). We also report the results of additional phantom and mouse studies. The MuPET scanner, which is integrated with a CT camera, is based on the photomultiplier-quadrant-sharing concept and comprises 180 blocks of 13 × 13 lutetium yttrium oxyorthosilicate crystals (1.24 × 1.4 × 9.5 mm(3)) and 210 low-cost 19-mm photomultipliers. The camera has 78 detector rings, with an 11.6-cm axial field of view and a ring diameter of 16.6 cm. We measured the energy resolution, scatter fraction, sensitivity, spatial resolution, and counting rate performance of the scanner. In addition, we scanned the NEMA image-quality phantom, Micro Deluxe and Ultra-Micro Hot Spot phantoms, and 2 healthy mice. The system average energy resolution was 14% at 511 keV. The average spatial resolution at the center of the field of view was about 1.2 mm, improving to 0.8 mm and remaining below 1.2 mm in the central 6-cm field of view when a resolution-recovery method was used. The absolute sensitivity of the camera was 6.38% for an energy window of 350-650 keV and a coincidence timing window of 3.4 ns. The system scatter fraction was 11.9% for the NEMA mouselike phantom and 28% for the ratlike phantom. The maximum noise-equivalent counting rate was 1,100 at 57 MBq for the mouselike phantom and 352 kcps at 65 MBq for the ratlike phantom. The 1-mm fillable rod was clearly observable using the NEMA image-quality phantom. The images of the Ultra-Micro Hot Spot phantom also showed the 1-mm hot rods. In the mouse studies, both the left and right ventricle walls were clearly observable, as were the Harderian glands. The MuPET camera has excellent resolution, sensitivity, counting rate, and imaging performance. The data show it is a powerful scanner for preclinical animal study and pharmaceutical development.

SU-C-BRF-05: Design and Geometric Validation of An Externally and Internally Deformable, Programmable Lung Motion Phantom

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheung, Y; Sawant, A

Purpose: Most clinically-deployed strategies for respiratory motion management in lung radiotherapy (e.g., gating, tracking) use external markers that serve as surrogates for tumor motion. However, typical lung phantoms used to validate these strategies are rigid-exterior+rigid-interior or rigid-exterior+deformable-interior. Neither class adequately represents the human anatomy, which is deformable internally as well as externally. We describe the construction and experimental validation of a more realistic, externally- and internally-deformable, programmable lung phantom. Methods: The outer shell of a commercially-available lung phantom (RS- 1500, RSD Inc.) was used. The shell consists of a chest cavity with a flexible anterior surface, and embedded vertebrae, rib-cagemore » and sternum. A 3-axis platform was programmed with sinusoidal and six patient-recorded lung tumor trajectories. The platform was used to drive a rigid foam ‘diaphragm’ that compressed/decompressed the phantom interior. Experimental characterization comprised of mapping the superior-inferior (SI) and anterior-posterior (AP) trajectories of external and internal radioopaque markers with kV x-ray fluoroscopy and correlating these with optical surface monitoring using the in-room VisionRT system. Results: The phantom correctly reproduced the programmed motion as well as realistic effects such as hysteresis. The reproducibility of marker trajectories over multiple runs for sinusoidal as well as patient traces, as characterized by fluoroscopy, was within 0.4 mm RMS error for internal as well as external markers. The motion trajectories of internal and external markers as measured by fluoroscopy were found to be highly correlated (R=0.97). Furthermore, motion trajectories of arbitrary points on the deforming phantom surface, as recorded by the VisionRT system also showed a high correlation with respect to the fluoroscopically-measured trajectories of internal markers (R=0.92). Conclusion: We have developed a realistic externally- and internally-deformable lung phantom that will serve as a valuable tool for clinical QA and motion management research. This work was supported through funding from the NIH and VisionRT Ltd. Amit Sawant has research funding from Varian Medical Systems, VisionRT and Elekta.« less

Design and application of a structured phantom for detection performance comparison between breast tomosynthesis and digital mammography

NASA Astrophysics Data System (ADS)

Cockmartin, L.; Marshall, N. W.; Zhang, G.; Lemmens, K.; Shaheen, E.; Van Ongeval, C.; Fredenberg, E.; Dance, D. R.; Salvagnini, E.; Michielsen, K.; Bosmans, H.

2017-02-01

This paper introduces and applies a structured phantom with inserted target objects for the comparison of detection performance of digital breast tomosynthesis (DBT) against 2D full field digital mammography (FFDM). The phantom consists of a 48 mm thick breast-shaped polymethyl methacrylate (PMMA) container filled with water and PMMA spheres of different diameters. Three-dimensionally (3D) printed spiculated masses (diameter range: 3.8-9.7 mm) and non-spiculated masses (1.6-6.2 mm) along with microcalcifications (90-250 µm) were inserted as targets. Reproducibility of the phantom application was studied on a single system using 30 acquisitions. Next, the phantom was evaluated on five different combined FFDM & DBT systems and target detection was compared for FFDM and DBT modes. Ten phantom images in both FFDM and DBT modes were acquired on these 5 systems using automatic exposure control. Five readers evaluated target detectability. Images were read with the four-alternative forced-choice (4-AFC) paradigm, with always one segment including a target and 3 normal background segments. The percentage of correct responses (PC) was assessed based on 10 trials of each reader for each object type, size and imaging modality. Additionally, detection threshold diameters at 62.5 PC were assessed via non-linear regression fitting of the psychometric curve. The reproducibility study showed no significant differences in PC values. Evaluation of target detection in FFDM showed that microcalcification detection thresholds ranged between 110 and 118 µm and were similar compared to the detection in DBT (range of 106-158 µm). In DBT, detection of both mass types increased significantly (p  =  0.0001 and p  =  0.0002 for non-spiculated and spiculated masses respectively) compared to FFDM, achieving almost 100% detection for all spiculated mass diameters. In conclusion, a structured phantom with inserted targets was able to show evidence for detectability differences between FFDM and DBT modes for five commercial systems. This phantom has potential for application in task-based assessment at acceptance and commissioning testing of DBT systems.

A generic high-dose rate {sup 192}Ir brachytherapy source for evaluation of model-based dose calculations beyond the TG-43 formalism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ballester, Facundo, E-mail: Facundo.Ballester@uv.es; Carlsson Tedgren, Åsa; Granero, Domingo

Purpose: In order to facilitate a smooth transition for brachytherapy dose calculations from the American Association of Physicists in Medicine (AAPM) Task Group No. 43 (TG-43) formalism to model-based dose calculation algorithms (MBDCAs), treatment planning systems (TPSs) using a MBDCA require a set of well-defined test case plans characterized by Monte Carlo (MC) methods. This also permits direct dose comparison to TG-43 reference data. Such test case plans should be made available for use in the software commissioning process performed by clinical end users. To this end, a hypothetical, generic high-dose rate (HDR) {sup 192}Ir source and a virtual watermore » phantom were designed, which can be imported into a TPS. Methods: A hypothetical, generic HDR {sup 192}Ir source was designed based on commercially available sources as well as a virtual, cubic water phantom that can be imported into any TPS in DICOM format. The dose distribution of the generic {sup 192}Ir source when placed at the center of the cubic phantom, and away from the center under altered scatter conditions, was evaluated using two commercial MBDCAs [Oncentra{sup ®} Brachy with advanced collapsed-cone engine (ACE) and BrachyVision ACUROS{sup TM}]. Dose comparisons were performed using state-of-the-art MC codes for radiation transport, including ALGEBRA, BrachyDose, GEANT4, MCNP5, MCNP6, and PENELOPE2008. The methodologies adhered to recommendations in the AAPM TG-229 report on high-energy brachytherapy source dosimetry. TG-43 dosimetry parameters, an along-away dose-rate table, and primary and scatter separated (PSS) data were obtained. The virtual water phantom of (201){sup 3} voxels (1 mm sides) was used to evaluate the calculated dose distributions. Two test case plans involving a single position of the generic HDR {sup 192}Ir source in this phantom were prepared: (i) source centered in the phantom and (ii) source displaced 7 cm laterally from the center. Datasets were independently produced by different investigators. MC results were then compared against dose calculated using TG-43 and MBDCA methods. Results: TG-43 and PSS datasets were generated for the generic source, the PSS data for use with the ACE algorithm. The dose-rate constant values obtained from seven MC simulations, performed independently using different codes, were in excellent agreement, yielding an average of 1.1109 ± 0.0004 cGy/(h U) (k = 1, Type A uncertainty). MC calculated dose-rate distributions for the two plans were also found to be in excellent agreement, with differences within type A uncertainties. Differences between commercial MBDCA and MC results were test, position, and calculation parameter dependent. On average, however, these differences were within 1% for ACUROS and 2% for ACE at clinically relevant distances. Conclusions: A hypothetical, generic HDR {sup 192}Ir source was designed and implemented in two commercially available TPSs employing different MBDCAs. Reference dose distributions for this source were benchmarked and used for the evaluation of MBDCA calculations employing a virtual, cubic water phantom in the form of a CT DICOM image series. The implementation of a generic source of identical design in all TPSs using MBDCAs is an important step toward supporting univocal commissioning procedures and direct comparisons between TPSs.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao Hewei; Fahrig, Rebecca; Bennett, N. Robert

Purpose: Scatter correction is a major challenge in x-ray imaging using large area detectors. Recently, the authors proposed a promising scatter correction method for x-ray computed tomography (CT) using primary modulation. Proof of concept was previously illustrated by Monte Carlo simulations and physical experiments on a small phantom with a simple geometry. In this work, the authors provide a quantitative evaluation of the primary modulation technique and demonstrate its performance in applications where scatter correction is more challenging. Methods: The authors first analyze the potential errors of the estimated scatter in the primary modulation method. On two tabletop CT systems,more » the method is investigated using three phantoms: A Catphan(c)600 phantom, an anthropomorphic chest phantom, and the Catphan(c)600 phantom with two annuli. Two different primary modulators are also designed to show the impact of the modulator parameters on the scatter correction efficiency. The first is an aluminum modulator with a weak modulation and a low modulation frequency, and the second is a copper modulator with a strong modulation and a high modulation frequency. Results: On the Catphan(c)600 phantom in the first study, the method reduces the error of the CT number in the selected regions of interest (ROIs) from 371.4 to 21.9 Hounsfield units (HU); the contrast to noise ratio also increases from 10.9 to 19.2. On the anthropomorphic chest phantom in the second study, which represents a more difficult case due to the high scatter signals and object heterogeneity, the method reduces the error of the CT number from 327 to 19 HU in the selected ROIs and from 31.4% to 5.7% on the overall average. The third study is to investigate the impact of object size on the efficiency of our method. The scatter-to-primary ratio estimation error on the Catphan(c)600 phantom without any annulus (20 cm in diameter) is at the level of 0.04, it rises to 0.07 and 0.1 on the phantom with an elliptical annulus (30 cm in the minor axis and 38 cm in the major axis) and with a circular annulus (38 cm in diameter). Conclusions: On the three phantom studies, good scatter correction performance of the proposed method has been demonstrated using both image comparisons and quantitative analysis. The theory and experiments demonstrate that a strong primary modulation that possesses a low transmission factor and a high modulation frequency is preferred for high scatter correction accuracy.« less

An Integrated System for Superharmonic Contrast-Enhanced Ultrasound Imaging: Design and Intravascular Phantom Imaging Study.

PubMed

Li, Yang; Ma, Jianguo; Martin, K Heath; Yu, Mingyue; Ma, Teng; Dayton, Paul A; Jiang, Xiaoning; Shung, K Kirk; Zhou, Qifa

2016-09-01

Superharmonic contrast-enhanced ultrasound imaging, also called acoustic angiography, has previously been used for the imaging of microvasculature. This approach excites microbubble contrast agents near their resonance frequency and receives echoes at nonoverlapping superharmonic bandwidths. No integrated system currently exists could fully support this application. To fulfill this need, an integrated dual-channel transmit/receive system for superharmonic imaging was designed, built, and characterized experimentally. The system was uniquely designed for superharmonic imaging and high-resolution B-mode imaging. A complete ultrasound system including a pulse generator, a data acquisition unit, and a signal processing unit were integrated into a single package. The system was controlled by a field-programmable gate array, on which multiple user-defined modes were implemented. A 6-, 35-MHz dual-frequency dual-element intravascular ultrasound transducer was designed and used for imaging. The system successfully obtained high-resolution B-mode images of coronary artery ex vivo with 45-dB dynamic range. The system was capable of acquiring in vitro superharmonic images of a vasa vasorum mimicking phantom with 30-dB contrast. It could detect a contrast agent filled tissue mimicking tube of 200 μm diameter. For the first time, high-resolution B-mode images and superharmonic images were obtained in an intravascular phantom, made possible by the dedicated integrated system proposed. The system greatly reduced the cost and complexity of the superharmonic imaging intended for preclinical study. Significant: The system showed promise for high-contrast intravascular microvascular imaging, which may have significant importance in assessment of the vasa vasorum associated with atherosclerotic plaques.

Automatic exposure control systems designed to maintain constant image noise: effects on computed tomography dose and noise relative to clinically accepted technique charts.

PubMed

Favazza, Christopher P; Yu, Lifeng; Leng, Shuai; Kofler, James M; McCollough, Cynthia H

2015-01-01

To compare computed tomography dose and noise arising from use of an automatic exposure control (AEC) system designed to maintain constant image noise as patient size varies with clinically accepted technique charts and AEC systems designed to vary image noise. A model was developed to describe tube current modulation as a function of patient thickness. Relative dose and noise values were calculated as patient width varied for AEC settings designed to yield constant or variable noise levels and were compared to empirically derived values used by our clinical practice. Phantom experiments were performed in which tube current was measured as a function of thickness using a constant-noise-based AEC system and the results were compared with clinical technique charts. For 12-, 20-, 28-, 44-, and 50-cm patient widths, the requirement of constant noise across patient size yielded relative doses of 5%, 14%, 38%, 260%, and 549% and relative noises of 435%, 267%, 163%, 61%, and 42%, respectively, as compared with our clinically used technique chart settings at each respective width. Experimental measurements showed that a constant noise-based AEC system yielded 175% relative noise for a 30-cm phantom and 206% relative dose for a 40-cm phantom compared with our clinical technique chart. Automatic exposure control systems that prescribe constant noise as patient size varies can yield excessive noise in small patients and excessive dose in obese patients compared with clinically accepted technique charts. Use of noise-level technique charts and tube current limits can mitigate these effects.

Evaluation of techniques for slice sensitivity profile measurement and analysis

PubMed Central

Greene, Travis C.

2014-01-01

The purpose of this study was to compare the resulting full width at half maximum of slice sensitivity profiles (SSP) generated by several commercially available point response phantoms, and determine an appropriate imaging technique and analysis method. Four CT phantoms containing point response objects designed to produce a delta impulse signal used in this study: a Fluke CT‐SSP phantom, a Gammex 464, a CatPhan 600, and a Kagaku Micro Disc phantom. Each phantom was imaged using 120 kVp, 325 mAs, head scan field of view, 32×0.625 mm helical scan with a 20 mm beam width and a pitch of 0.969. The acquired images were then reconstructed into all available slice thicknesses (0.625 mm−5.0 mm). A computer program was developed to analyze the images of each dataset for generating a SSP from which the full width at half maximum (FWHM) was determined. Two methods for generating SSPs were evaluated and compared by choosing the mean vs. maximum value in the ROI, along with two methods for evaluating the FWHM of the SSP, linear interpolation and Gaussian curve fitting. FWHMs were compared with the manufacturer's specifications using percent error and z‐test with a significance value of p<0.05. The FWHMs from each phantom were not significantly different (p≥0.089) with an average error of 3.5%. The FWHMs from SSPs generated from the mean value were statistically different (p≤3.99×1013). The FWHMs from the different FWHM methods were not statistically different (p≤0.499). Evaluation of the SSP is dependent on the ROI value used. The maximum value from the ROI should be used to generate the SSP whenever possible. SSP measurement is independent of the phantoms used in this study. PACS number: 87. PMID:24710429

Dosimetric impact of the AeroForm tissue expander in postmastectomy radiation therapy: an ex vivo analysis.

PubMed

Moni, Janaki; Saleeby, Jonathan; Bannon, Elizabeth; Lo, Yuan-Chyuan; Fitzgerald, Thomas J

2015-01-01

To evaluate the effect of the AeroForm (AirXpanders Inc, Palo Alto, CA) tissue expander on the dose distribution in a phantom from a simulated postmastectomy radiation treatment for breast cancer. Experiments were conducted to determine the effect on the dose distribution with the metallic reservoir irradiated independently and with the entire AeroForm tissue expander placed on a RANDO phantom (The Phantom Laboratory, Salem, NY). The metallic reservoir was irradiated on a block of solid water with film at various depths ranging from 0 to 8.2 cm from the surface. The intact 400 cc AeroForm was inflated to full capacity and irradiated while positioned on a RANDO phantom, with 12 optically stimulated luminescent dosimeters (OSLDs) placed at clinically relevant expander-tissue interface points. Film dosimetry with the reservoir perpendicular to film reveals 40% transmission at a depth of 0.7 cm, which increases to 60% at a depth of 8.2 cm. In the parallel position, the results vary depending on which area under the reservoir is examined, indicating that the reservoir is not a uniformly dense object. Testing of the intact expander on the phantom revealed that the average percent difference (measured vs expected dose) was 2.7%, σ = 6.2% with heterogeneity correction and 3.7%, σ = 2.4% without heterogeneity correction. The only position where the OSLD readings were consistently higher than the calculated dose by >5% was at position 1, just deep to the canister at the expander-phantom interface. At this position, the readings varied from 5.2% to 14.5%, regardless of heterogeneity correction. Film dosimetry demonstrated beam attenuation in the shadow of the metallic reservoir in the expander. This decrease in dose was not reproduced on the intact expander on the phantom designed to replicate a clinical setup. Copyright © 2015 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.

Technical Note: FreeCT_wFBP: A robust, efficient, open-source implementation of weighted filtered backprojection for helical, fan-beam CT.

PubMed

Hoffman, John; Young, Stefano; Noo, Frédéric; McNitt-Gray, Michael

2016-03-01

With growing interest in quantitative imaging, radiomics, and CAD using CT imaging, the need to explore the impacts of acquisition and reconstruction parameters has grown. This usually requires extensive access to the scanner on which the data were acquired and its workflow is not designed for large-scale reconstruction projects. Therefore, the authors have developed a freely available, open-source software package implementing a common reconstruction method, weighted filtered backprojection (wFBP), for helical fan-beam CT applications. FreeCT_wFBP is a low-dependency, GPU-based reconstruction program utilizing c for the host code and Nvidia CUDA C for GPU code. The software is capable of reconstructing helical scans acquired with arbitrary pitch-values, and sampling techniques such as flying focal spots and a quarter-detector offset. In this work, the software has been described and evaluated for reconstruction speed, image quality, and accuracy. Speed was evaluated based on acquisitions of the ACR CT accreditation phantom under four different flying focal spot configurations. Image quality was assessed using the same phantom by evaluating CT number accuracy, uniformity, and contrast to noise ratio (CNR). Finally, reconstructed mass-attenuation coefficient accuracy was evaluated using a simulated scan of a FORBILD thorax phantom and comparing reconstructed values to the known phantom values. The average reconstruction time evaluated under all flying focal spot configurations was found to be 17.4 ± 1.0 s for a 512 row × 512 column × 32 slice volume. Reconstructions of the ACR phantom were found to meet all CT Accreditation Program criteria including CT number, CNR, and uniformity tests. Finally, reconstructed mass-attenuation coefficient values of water within the FORBILD thorax phantom agreed with original phantom values to within 0.0001 mm(2)/g (0.01%). FreeCT_wFBP is a fast, highly configurable reconstruction package for third-generation CT available under the GNU GPL. It shows good performance with both clinical and simulated data.

Dynamics and control of escape and rescue from a tumbling spacecraft

NASA Technical Reports Server (NTRS)

Kaplan, M. H.

1972-01-01

Papers on the problem of controlling a tumbling spacecraft before crew rescue is affected are presented. Fluid jets are considered; It is concluded that a gas jet results in long tumble times and low utilization efficiencies and a liquid jet appears more attractive because it can be directed. A conceptual design of an unmanned antitumbling module for automatic dock and detumble is formulated, and analyses of its dynamics and control, synthesis of position and attitude control systems, and sequence of operations are given. The minimum time detumble operation is analyzed with respect to (1) to a constraint on the magnitude of the control moment vector and (2) to constraints on the magnitude of each of the three components of the control moment vector. Internal passive and active mechanisms of energy dissipation are also considered. Structural flexibility modelling techniques and detumbling effects of structural flexibility on free-tumbling motion, are reviewed. Mass expulsion, momentum exchange, and moveable mass techniques are described, and methods of analyzing these devices are surveyed.

Aeroacoustic Measurements of a Wing/Slat Model. [Research conducted at the Quiet Flow Facility of the NASA Langley Research Center

NASA Technical Reports Server (NTRS)

Mendoza, Jeff M.; Brooks, Thomas F.; Humphreys, William M.

2002-01-01

Aeroacoustic evaluations of high-lift devices have been carried out in the Quiet Flow Facility of the NASA Langley Research Center. The present paper deals with detailed flow and acoustic measurements that have been made to understand, and to possibly predict and reduce, the noise from a wing leading edge slat configuration. The acoustic database is obtained by a moveable Small Aperture Directional Array (SADA) of microphones designed to electronically steer to different portions of models under study. The slat is shown to be a uniform distributed noise source. The data was processed such that spectra and directivity were determined with respect to a one-foot span of slat. The spectra are normalized in various fashions to demonstrate slat noise character. In order to equate portions of the spectra to different slat noise components, trailing edge noise predictions using measured slat boundary layer parameters as inputs are compared to the measured slat noise spectra.

AIM being prepared for integrated testing and flight simulation

NASA Image and Video Library

2007-03-24

In Building 1555 on North Vandenberg Air Force Base in California, technicians lower the AIM spacecraft onto a moveable stand. AIM, which stands for Aeronomy of Ice in the Mesosphere, is being prepared for integrated testing and a flight simulation. The AIM spacecraft will fly three instruments designed to study polar mesospheric clouds located at the edge of space, 50 miles above the Earth's surface in the coldest part of the planet's atmosphere. The mission's primary goal is to explain why these clouds form and what has caused them to become brighter and more numerous and appear at lower latitudes in recent years. AIM's results will provide the basis for the study of long-term variability in the mesospheric climate and its relationship to global climate change. AIM is scheduled to be mated to its launch vehicle, Orbital Sciences' Pegasus XL, during the second week of April, after which final inspections will be conducted. Launch is scheduled for April 25.

Investigation of land-use spectral signatures. Ph.D. Thesis. Final Report

NASA Technical Reports Server (NTRS)

Hagewood, J. F.

1975-01-01

A technique was developed to obtain bidirectional reflectance data from natural surfaces by using a folding mirror to transfer the reflected energy from the test surface to a spectroradiometer. The folding mirror was a first surface reflector made by stretching Mylar vacuum coated with aluminum over a light weight frame. The optically folding mirror was positioned over the test surfaces with a moveable platform for both laboratory and field tests. Field tests were conducted using a tethered balloon system to position the folding mirror. A spectroradiometer was designed and built specifically for this investigation. The spectroradiometer had an angular field of view of twenty-four minutes in one axis and ten minutes in the other axis. The radiometer was capable of detecting energies in small bandwidths throughout the electromagnetic spectrum from 0.3 microns to 3.0 microns. Bidirectional reflectance data and variations in the data with source angles were obtained for Saint Augustine grass, Bermuda grass, and a black alluvium soil from the Mississippi River delta.

KSC-07pd0789

NASA Image and Video Library

2007-03-24

KENNEDY SPACE CENTER, FLA. -- In Building 1555 on North Vandenberg Air Force Base in California, technicians lower the AIM spacecraft onto a moveable stand. AIM, which stands for Aeronomy of Ice in the Mesosphere, is being prepared for integrated testing and a flight simulation. The AIM spacecraft will fly three instruments designed to study polar mesospheric clouds located at the edge of space, 50 miles above the Earth's surface in the coldest part of the planet's atmosphere. The mission's primary goal is to explain why these clouds form and what has caused them to become brighter and more numerous and appear at lower latitudes in recent years. AIM's results will provide the basis for the study of long-term variability in the mesospheric climate and its relationship to global climate change. AIM is scheduled to be mated to its launch vehicle, Orbital Sciences' Pegasus XL, during the second week of April, after which final inspections will be conducted. Launch is scheduled for April 25.

An Aeroacoustic Study of a Leading Edge Slat Configuration

NASA Technical Reports Server (NTRS)

Mendoza, J. M.; Brooks, T. F.; Humphreys, W. M., Jr.

2002-01-01

Aeroacoustic evaluations of high-lift devices have been carried out in the Quiet Flow Facility of the NASA Langley Research Center. The present paper describes detailed flow and acoustic measurements that have been made in order to better understand the noise generated from airflow over a wing leading edge slat configuration, and to possibly predict and reduce this noise source. The acoustic database is obtained by a moveable Small Aperture Directional Array of microphones designed to electronically steer to different portions of models under study. The slat is shown to be a uniform distributed noise source. The data was processed such that spectra and directivity were determined with respect to a one-foot span of slat. The spectra are normalized in various fashions to demonstrate slat noise character. In order to equate portions of the spectra to different slat noise components, trailing edge noise predictions using measured slat boundary layer parameters as inputs are compared to the measured slat noise spectra.

A dual resolution measurement based Monte Carlo simulation technique for detailed dose analysis of small volume organs in the skull base region

NASA Astrophysics Data System (ADS)

Yeh, Chi-Yuan; Tung, Chuan-Jung; Chao, Tsi-Chain; Lin, Mu-Han; Lee, Chung-Chi

2014-11-01

The purpose of this study was to examine dose distribution of a skull base tumor and surrounding critical structures in response to high dose intensity-modulated radiosurgery (IMRS) with Monte Carlo (MC) simulation using a dual resolution sandwich phantom. The measurement-based Monte Carlo (MBMC) method (Lin et al., 2009) was adopted for the study. The major components of the MBMC technique involve (1) the BEAMnrc code for beam transport through the treatment head of a Varian 21EX linear accelerator, (2) the DOSXYZnrc code for patient dose simulation and (3) an EPID-measured efficiency map which describes non-uniform fluence distribution of the IMRS treatment beam. For the simulated case, five isocentric 6 MV photon beams were designed to deliver a total dose of 1200 cGy in two fractions to the skull base tumor. A sandwich phantom for the MBMC simulation was created based on the patient's CT scan of a skull base tumor [gross tumor volume (GTV)=8.4 cm3] near the right 8th cranial nerve. The phantom, consisted of a 1.2-cm thick skull base region, had a voxel resolution of 0.05×0.05×0.1 cm3 and was sandwiched in between 0.05×0.05×0.3 cm3 slices of a head phantom. A coarser 0.2×0.2×0.3 cm3 single resolution (SR) phantom was also created for comparison with the sandwich phantom. A particle history of 3×108 for each beam was used for simulations of both the SR and the sandwich phantoms to achieve a statistical uncertainty of <2%. Our study showed that the planning target volume (PTV) receiving at least 95% of the prescribed dose (VPTV95) was 96.9%, 96.7% and 99.9% for the TPS, SR, and sandwich phantom, respectively. The maximum and mean doses to large organs such as the PTV, brain stem, and parotid gland for the TPS, SR and sandwich MC simulations did not show any significant difference; however, significant dose differences were observed for very small structures like the right 8th cranial nerve, right cochlea, right malleus and right semicircular canal. Dose volume histogram (DVH) analyses revealed much smoother DVH curves for the dual resolution sandwich phantom when compared to the SR phantom. In conclusion, MBMC simulations using a dual resolution sandwich phantom improved simulation spatial resolution for skull base IMRS therapy. More detailed dose analyses for small critical structures can be made available to help in clinical judgment.

Accurate Measurement of Bone Density with QCT

NASA Technical Reports Server (NTRS)

Cleek, Tammy M.; Beaupre, Gary S.; Matsubara, Miki; Whalen, Robert T.; Dalton, Bonnie P. (Technical Monitor)

2002-01-01

The objective of this study was to determine the accuracy of bone density measurement with a new OCT technology. A phantom was fabricated using two materials, a water-equivalent compound and hydroxyapatite (HA), combined in precise proportions (QRM GrnbH, Germany). The phantom was designed to have the approximate physical size and range in bone density as a human calcaneus, with regions of 0, 50, 100, 200, 400, and 800 mg/cc HA. The phantom was scanned at 80, 120 and 140 KVp with a GE CT/i HiSpeed Advantage scanner. A ring of highly attenuating material (polyvinyl chloride or teflon) was slipped over the phantom to alter the image by introducing non-axi-symmetric beam hardening. Images were corrected with a new OCT technology using an estimate of the effective X-ray beam spectrum to eliminate beam hardening artifacts. The algorithm computes the volume fraction of HA and water-equivalent matrix in each voxel. We found excellent agreement between expected and computed HA volume fractions. Results were insensitive to beam hardening ring material, HA concentration, and scan voltage settings. Data from all 3 voltages with a best fit linear regression are displays.

Experimental investigation of the abrasive crown dynamics in orbital atherectomy.

PubMed

Zheng, Yihao; Belmont, Barry; Shih, Albert J

2016-07-01

Orbital atherectomy is a catheter-based minimally invasive procedure to modify the plaque within atherosclerotic arteries using a diamond abrasive crown. This study was designed to investigate the crown motion and its corresponding contact force with the vessel. To this end, a transparent arterial tissue-mimicking phantom made of polyvinyl chloride was developed, a high-speed camera and image processing technique were utilized to visualize and quantitatively analyze the crown motion in the vessel phantom, and a piezoelectric dynamometer measured the forces on the phantom during the procedure. Observed under typical orbital atherectomy rotational speeds of 60,000, 90,000, and 120,000rpm in a 4.8mm caliber vessel phantom, the crown motion was a combination of high-frequency rotation at 1000, 1500, and 1660.4-1866.1Hz and low-frequency orbiting at 18, 38, and 40Hz, respectively. The measured forces were also composed of these high and low frequencies, matching well with the rotation of the eccentric crown and the associated orbital motion. The average peak force ranged from 0.1 to 0.4N at different rotational speeds. Copyright © 2016 IPEM. Published by Elsevier Ltd. All rights reserved.

An Approach in Radiation Therapy Treatment Planning: A Fast, GPU-Based Monte Carlo Method.

PubMed

Karbalaee, Mojtaba; Shahbazi-Gahrouei, Daryoush; Tavakoli, Mohammad B

2017-01-01

An accurate and fast radiation dose calculation is essential for successful radiation radiotherapy. The aim of this study was to implement a new graphic processing unit (GPU) based radiation therapy treatment planning for accurate and fast dose calculation in radiotherapy centers. A program was written for parallel running based on GPU. The code validation was performed by EGSnrc/DOSXYZnrc. Moreover, a semi-automatic, rotary, asymmetric phantom was designed and produced using a bone, the lung, and the soft tissue equivalent materials. All measurements were performed using a Mapcheck dosimeter. The accuracy of the code was validated using the experimental data, which was obtained from the anthropomorphic phantom as the gold standard. The findings showed that, compared with those of DOSXYZnrc in the virtual phantom and for most of the voxels (>95%), <3% dose-difference or 3 mm distance-to-agreement (DTA) was found. Moreover, considering the anthropomorphic phantom, compared to the Mapcheck dose measurements, <5% dose-difference or 5 mm DTA was observed. Fast calculation speed and high accuracy of GPU-based Monte Carlo method in dose calculation may be useful in routine radiation therapy centers as the core and main component of a treatment planning verification system.

3D perfused brain phantom for interstitial ultrasound thermal therapy and imaging: design, construction and characterization

NASA Astrophysics Data System (ADS)

Martínez, José M.; Jarosz, Boguslaw J.

2015-03-01

Thermal therapy has emerged as an independent modality of treating some tumors. In many clinics the hyperthermia, one of the thermal therapy modalities, has been used adjuvant to radio- or chemotherapy to substantially improve the clinical treatment outcomes. In this work, a methodology for building a realistic brain phantom for interstitial ultrasound low dose-rate thermal therapy of the brain is proposed. A 3D brain phantom made of the tissue mimicking material (TMM) had the acoustic and thermal properties in the 20-32 °C range, which is similar to that of a brain at 37 °C. The phantom had 10-11% by mass of bovine gelatin powder dissolved in ethylene glycol. The TMM sonicated at 1 MHz, 1.6 MHz and 2.5 MHz yielded the amplitude attenuation coefficients of 62  ±  1 dB m-1, 115  ±  4 dB m-1 and 175  ±  9 dB m-1, respectively. The density and acoustic speed determination at room temperature (~24 °C) gave 1040  ±  40 kg m-3 and 1545  ±  44 m s-1, respectively. The average thermal conductivity was 0.532 W m-1 K-1. The T1 and T2 values of the TMM were 207  ±  4 and 36.2  ±  0.4 ms, respectively. We envisage the use of our phantom for treatment planning and for quality assurance in MRI based temperature determination. Our phantom preparation methodology may be readily extended to other thermal therapy technologies.

Evaluation of effective dose for a patient under Ga-67 nuclear examination using TLD, water phantom and a simplified model

PubMed Central

Chu, Kuang Hua; Lin, Yu Ting; Hsu, Chia Chun; Chen, Chien Yi; Pan, Lung Kwang

2012-01-01

This study evaluated the effective dose of Ga-67 for a patient undergoing Ga-67 citrate nuclear examination by applying thermoluminescent dosimeter (TLD) technique and an indigenous water phantom. The Ga-67 radionuclide remaining in the body inevitably generated a measurable internal dose even though gamma camera scanning took only minutes to complete the clinical examination. For effective simulation of the cumulated effective dose for a patient undergoing examination, 150 TLDs were placed inside the water phantom for 6 days to monitor the gamma ray dose from the distributed Ga-67 citrate solution. The inserted TLDs represented internal organs, and the effective dose was calculated according to data in the ICRP-60 report. The water phantom was designed to model the body of a healthy human weighing 70 kg, and the water that was mixed with Ga-67 citrate solution was slowly replaced with fresh feed water to yield the required biological half life of the phantom. After continuously feeding in fresh water throughout the 6 days of TLD exposure, the TLDs were analyzed to determine the effective doses from the various biological half lives of the phantom. The derived effective dose of 185 MBq Ga-67 citrate solution for male/female (M/F) was 10.7/12.2, 10.7/12.0, 8.7/9.9 and 6.0/6.8 mSv, of biological half lives of 6.0, 4.5, 3.0 and 1.5 days, respectively. Although these experimental results correlated well with earlier empirical studies, they were lower than most calculated values. The cumulated uncertainty in the effective dose was 12.5–19.4%, which was acceptable in terms of both TLD counting statistic and reproducibility. PMID:22915780

3D printing of microtube in solid phantom to simulate tissue oxygenation and perfusion (Conference Presentation)

NASA Astrophysics Data System (ADS)

Lv, Xiang; Xue, Yue; Wang, Haili; Shen, Shu Wei; Zhou, Ximing; Liu, Guangli; Dong, Erbao; Xu, Ronald X.

2017-03-01

Tissue-simulating phantoms with interior vascular network may facilitate traceable calibration and quantitative validation of many medical optical devices. However, a solid phantom that reliably simulates tissue oxygenation and blood perfusion is still not available. This paper presents a new method to fabricate hollow microtubes for blood vessel simulation in solid phantoms. The fabrication process combines ultraviolet (UV) rapid prototyping technique with fluid mechanics of a coaxial jet flow. Polydimethylsiloxane (PDMS) and a UV-curable polymer are mixed at the designated ratio and extruded through a coaxial needle device to produce a coaxial jet flow. The extruded jet flow is quickly photo-polymerized by ultraviolet (UV) light to form vessel-simulating solid structures at different sizes ranging from 700 μm to 1000 μm. Microtube structures with adequate mechanical properties can be fabricated by adjusting material compositions and illumination intensity. Curved, straight and stretched microtubes can be formed by adjusting the extrusion speed of the materials and the speed of the 3D printing platform. To simulate vascular structures in biologic tissue, we embed vessel-simulating microtubes in a gel wax phantom of 10 cm x10 cm x 5 cm at the depth from 1 to 2 mm. Bloods at different oxygenation and hemoglobin concentration levels are circulated through the microtubes at different flow rates in order to simulate different oxygenation and perfusion conditions. The simulated physiologic parameters are detected by a tissue oximeter and a laser speckle blood flow meter respectively and compared with the actual values. Our experiments demonstrate that the proposed 3D printing process is able to produce solid phantoms with simulated vascular networks for potential applications in medical device calibration and drug delivery studies.

Reproducing 2D breast mammography images with 3D printed phantoms

NASA Astrophysics Data System (ADS)

Clark, Matthew; Ghammraoui, Bahaa; Badal, Andreu

2016-03-01

Mammography is currently the standard imaging modality used to screen women for breast abnormalities and, as a result, it is a tool of great importance for the early detection of breast cancer. Physical phantoms are commonly used as surrogates of breast tissue to evaluate some aspects of the performance of mammography systems. However, most phantoms do not reproduce the anatomic heterogeneity of real breasts. New fabrication technologies, such as 3D printing, have created the opportunity to build more complex, anatomically realistic breast phantoms that could potentially assist in the evaluation of mammography systems. The primary objective of this work is to present a simple, easily reproducible methodology to design and print 3D objects that replicate the attenuation profile observed in real 2D mammograms. The secondary objective is to evaluate the capabilities and limitations of the competing 3D printing technologies, and characterize the x-ray properties of the different materials they use. Printable phantoms can be created using the open-source code introduced in this work, which processes a raw mammography image to estimate the amount of x-ray attenuation at each pixel, and outputs a triangle mesh object that encodes the observed attenuation map. The conversion from the observed pixel gray value to a column of printed material with equivalent attenuation requires certain assumptions and knowledge of multiple imaging system parameters, such as x-ray energy spectrum, source-to-object distance, compressed breast thickness, and average breast material attenuation. A detailed description of the new software, a characterization of the printed materials using x-ray spectroscopy, and an evaluation of the realism of the sample printed phantoms are presented.

Dosimetry audit of radiotherapy treatment planning systems.

PubMed

Bulski, Wojciech; Chełmiński, Krzysztof; Rostkowska, Joanna

2015-07-01

In radiotherapy Treatment Planning Systems (TPS) various calculation algorithms are used. The accuracy of dose calculations has to be verified. Numerous phantom types, detectors and measurement methodologies are proposed to verify the TPS calculations with dosimetric measurements. A heterogeneous slab phantom has been designed within a Coordinated Research Project (CRP) of the IAEA. The heterogeneous phantom was developed in the frame of the IAEA CRP. The phantom consists of frame slabs made with polystyrene and exchangeable inhomogeneity slabs equivalent to bone or lung tissue. Special inserts allow to position thermoluminescent dosimeters (TLD) capsules within the polystyrene slabs below the bone or lung equivalent slabs and also within the lung equivalent material. Additionally, there are inserts that allow to position films or ionisation chamber in the phantom. Ten Polish radiotherapy centres (of 30 in total) were audited during on-site visits. Six different TPSs and five calculation algorithms were examined in the presence of inhomogeneities. Generally, most of the results from TLD were within 5 % tolerance. Differences between doses calculated by TPSs and measured with TLD did not exceed 4 % for bone and polystyrene equivalent materials. Under the lung equivalent material, on the beam axis the differences were lower than 5 %, whereas inside the lung equivalent material, off the beam axis, in some cases they were of around 7 %. The TLD results were confirmed with the ionisation chamber measurements. The comparison results of the calculations and the measurements allow to detect limitations of TPS calculation algorithms. The audits performed with the use of heterogeneous phantom and TLD seem to be an effective tool for detecting the limitations in the TPS performance or beam configuration errors at audited radiotherapy departments. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Developing a mailed phantom to implement a local QA program in Egypt radiotherapy centers

NASA Astrophysics Data System (ADS)

Soliman, H. A.; Aletreby, M.

2016-07-01

In this work, a simple method that differs from the IAEA/WHO Thermoluminescent dosimeters (TLD) postal quality assurance (QA) program is developed. A small perspex; polymethyl methacrylate (PMMA), phantom measured 50 mm × 50 mm × 50 mm is constructed to be used for absorbed dose verification of high-energy photon beams in some major radiotherapy centers in Egypt. The phantom weighted only 140.7 g with two buildup covers weighted 14.8 and 43.19 g for the Cobalt-60 and the 6-MV X-ray beams, respectively. This phantom is aimed for use in the future's external audit/QA services in Egypt for the first time. TLD-700 chips are used for testing and investigating a convenient and national dosimetry QA program. Although the used methodology is comparable to previously introduced but new system; it has smaller size, less weight, and different more available material. Comparison with the previous similar designs is introduced. Theoretical calculations were done by the commercial Eclipse treatment planning system, implementing the pencil beam convolution algorithm to verify the accuracy of the experimental calculation of the dose conversion factor of water to the perspex phantom. The new constructed small phantom and methodology was applied in 10 participating radiotherapy centers. The absorbed dose was verified under the reference conditions for both 60Co and 6-MV high-energy photon beams. The checked beams were within the 5% limit except for four photon beams. There was an agreement of 0.2% between our experimental data and those previously published confirming the validity of the applied method in verifying radiotherapy absorbed dose.

A 3D-printed anatomical pancreas and kidney phantom for optimizing SPECT/CT reconstruction settings in beta cell imaging using 111In-exendin.

PubMed

Woliner-van der Weg, Wietske; Deden, Laura N; Meeuwis, Antoi P W; Koenrades, Maaike; Peeters, Laura H C; Kuipers, Henny; Laanstra, Geert Jan; Gotthardt, Martin; Slump, Cornelis H; Visser, Eric P

2016-12-01

Quantitative single photon emission computed tomography (SPECT) is challenging, especially for pancreatic beta cell imaging with 111 In-exendin due to high uptake in the kidneys versus much lower uptake in the nearby pancreas. Therefore, we designed a three-dimensionally (3D) printed phantom representing the pancreas and kidneys to mimic the human situation in beta cell imaging. The phantom was used to assess the effect of different reconstruction settings on the quantification of the pancreas uptake for two different, commercially available software packages. 3D-printed, hollow pancreas and kidney compartments were inserted into the National Electrical Manufacturers Association (NEMA) NU2 image quality phantom casing. These organs and the background compartment were filled with activities simulating relatively high and low pancreatic 111 In-exendin uptake for, respectively, healthy humans and type 1 diabetes patients. Images were reconstructed using Siemens Flash 3D and Hermes Hybrid Recon, with varying numbers of iterations and subsets and corrections. Images were visually assessed on homogeneity and artefacts, and quantitatively by the pancreas-to-kidney activity concentration ratio. Phantom images were similar to clinical images and showed comparable artefacts. All corrections were required to clearly visualize the pancreas. Increased numbers of subsets and iterations improved the quantitative performance but decreased homogeneity both in the pancreas and the background. Based on the phantom analyses, the Hybrid Recon reconstruction with 6 iterations and 16 subsets was found to be most suitable for clinical use. This work strongly contributed to quantification of pancreatic 111 In-exendin uptake. It showed how clinical images of 111 In-exendin can be interpreted and enabled selection of the most appropriate protocol for clinical use.

Experimental assessment of precision and accuracy of radiostereometric analysis for the determination of polyethylene wear in a total hip replacement model.

PubMed

Bragdon, Charles R; Malchau, Henrik; Yuan, Xunhua; Perinchief, Rebecca; Kärrholm, Johan; Börlin, Niclas; Estok, Daniel M; Harris, William H

2002-07-01

The purpose of this study was to develop and test a phantom model based on actual total hip replacement (THR) components to simulate the true penetration of the femoral head resulting from polyethylene wear. This model was used to study both the accuracy and the precision of radiostereometric analysis, RSA, in measuring wear. We also used this model to evaluate optimum tantalum bead configuration for this particular cup design when used in a clinical setting. A physical model of a total hip replacement (a phantom) was constructed which could simulate progressive, three-dimensional (3-D) penetration of the femoral head into the polyethylene component of a THR. Using a coordinate measuring machine (CMM) the positioning of the femoral head using the phantom was measured to be accurate to within 7 microm. The accuracy and precision of an RSA analysis system was determined from five repeat examinations of the phantom using various experimental set-ups of the phantom. The accuracy of the radiostereometric analysis, in this optimal experimental set-up studied was 33 microm for the medial direction, 22 microm for the superior direction, 86 microm for the posterior direction and 55 microm for the resultant 3-D vector length. The corresponding precision at the 95% confidence interval of the test results for repositioning the phantom five times, measured 8.4 microm for the medial direction, 5.5 microm for the superior direction, 16.0 microm for the posterior direction, and 13.5 microm for the resultant 3-D vector length. This in vitro model is proposed as a useful tool for developing a standard for the evaluation of radiostereometric and other radiographic methods used to measure in vivo wear.

Pixelized Measurement of (99m)Tc-HDP Micro Particles Formed in Gamma Correction Phantom Pinhole Scan: a Reference Study.

PubMed

Jung, Joo-Young; Cheon, Gi Jeong; Lee, Yun-Sang; Ha, Seunggyun; Chae, Mi-Hye; Chung, Yong-An; Yoon, Do Kyun; Bahk, Yong-Whee

2016-09-01

Currently, traumatic bone diseases are diagnosed by assessing the micro (99m)Tc-hydroxymethylene diphosphonate (HDP) uptake in injured trabeculae with ongoing osteoneogenesis demonstrated by gamma correction pinhole scan (GCPS). However, the mathematic size quantification of micro-uptake is not yet available. We designed and performed this phantom-based study to set up an in-vitro model of the mathematical calculation of micro-uptake by the pixelized measurement. The micro (99m)Tc-HDP deposits used in this study were spontaneously formed both in a large standard flood and small house-made dish phantoms. The processing was as follows: first, phantoms were flooded with distilled water and (99m)Tc-HDP was therein injected to induce micro (99m)Tc-HDP deposition; second, the deposits were scanned using parallel-hole and pinhole collimator to generally survey (99m)Tc-HDP deposition pattern; and third, the scans underwent gamma correction (GC) to discern individual deposits for size measurement. In original naïve scans, tracer distribution was simply nebulous in appearance and, hence, could not be measured. Impressively, however, GCPS could discern individual micro deposits so that they were calculated by pixelized measurement. Phantoms naturally formed micro (99m)Tc-HDP deposits that are analogous to (99m)Tc-HDP uptake on in-vivo bone scan. The smallest one we measured was 0.414 mm. Flooded phantoms and therein injected (99m)Tc-HDP form nebulous micro (99m)Tc-HDP deposits that are rendered discernible by GCPB and precisely calculable using pixelized measurement. This method can be used for precise quantitative and qualitative diagnosis of bone and joint diseases at the trabecular level.

The PACT trial: PAtient Centered Telerehabilitation: effectiveness of software-supported and traditional mirror therapy in patients with phantom limb pain following lower limb amputation: protocol of a multicentre randomised controlled trial.

PubMed

Rothgangel, Andreas Stefan; Braun, Susy; Schulz, Ralf Joachim; Kraemer, Matthias; de Witte, Luc; Beurskens, Anna; Smeets, Rob Johannes

2015-01-01

Non-pharmacological interventions such as mirror therapy are gaining increased recognition in the treatment of phantom limb pain; however, the evidence in people with phantom limb pain is still weak. In addition, compliance to self-delivered exercises is generally low. The aim of this randomised controlled study is to investigate the effectiveness of mirror therapy supported by telerehabilitation on the intensity, duration and frequency of phantom limb pain and limitations in daily activities compared to traditional mirror therapy and care as usual in people following lower limb amputation. A three-arm multi-centre randomised controlled trial will be performed. Participants will be randomly assigned to care as usual, traditional mirror therapy or mirror therapy supported by telerehabilitation. During the first 4 weeks, at least 10 individual sessions will take place in every group. After the first 4 weeks, participants will be encouraged to perform self-delivered exercises over a period of 6 weeks. Outcomes will be assessed at 4 and 10 weeks after baseline and at 6 months follow-up. The primary outcome measure is the average intensity of phantom limb pain during the last week. Secondary outcome measures include the different dimensions of phantom limb pain, pain-related limitations in daily activities, global perceived effect, pain-specific self-efficacy, and quality of life. Several questions concerning the study design that emerged during the preparation of this trial will be discussed. This will include how these questions were addressed and arguments for the choices that were made. Copyright © 2014 Australian Physiotherapy Association. Published by Elsevier B.V. All rights reserved.

Evolutionary Optimization of a Quadrifilar Helical Antenna

NASA Technical Reports Server (NTRS)

Lohn, Jason D.; Kraus, William F.; Linden, Derek S.; Clancy, Daniel (Technical Monitor)

2002-01-01

Automated antenna synthesis via evolutionary design has recently garnered much attention in the research literature. Evolutionary algorithms show promise because, among search algorithms, they are able to effectively search large, unknown design spaces. NASA's Mars Odyssey spacecraft is due to reach final Martian orbit insertion in January, 2002. Onboard the spacecraft is a quadrifilar helical antenna that provides telecommunications in the UHF band with landed assets, such as robotic rovers. Each helix is driven by the same signal which is phase-delayed in 90 deg increments. A small ground plane is provided at the base. It is designed to operate in the frequency band of 400-438 MHz. Based on encouraging previous results in automated antenna design using evolutionary search, we wanted to see whether such techniques could improve upon Mars Odyssey antenna design. Specifically, a co-evolutionary genetic algorithm is applied to optimize the gain and size of the quadrifilar helical antenna. The optimization was performed in-situ in the presence of a neighboring spacecraft structure. On the spacecraft, a large aluminum fuel tank is adjacent to the antenna. Since this fuel tank can dramatically affect the antenna's performance, we leave it to the evolutionary process to see if it can exploit the fuel tank's properties advantageously. Optimizing in the presence of surrounding structures would be quite difficult for human antenna designers, and thus the actual antenna was designed for free space (with a small ground plane). In fact, when flying on the spacecraft, surrounding structures that are moveable (e.g., solar panels) may be moved during the mission in order to improve the antenna's performance.

Development of a video-guided real-time patient motion monitoring system.

PubMed

Ju, Sang Gyu; Huh, Woong; Hong, Chae-Seon; Kim, Jin Sung; Shin, Jung Suk; Shin, Eunhyuk; Han, Youngyih; Ahn, Yong Chan; Park, Hee Chul; Choi, Doo Ho

2012-05-01

The authors developed a video image-guided real-time patient motion monitoring (VGRPM) system using PC-cams, and its clinical utility was evaluated using a motion phantom. The VGRPM system has three components: (1) an image acquisition device consisting of two PC-cams, (2) a main control computer with a radiation signal controller and warning system, and (3) patient motion analysis software developed in-house. The intelligent patient motion monitoring system was designed for synchronization with a beam on/off trigger signal in order to limit operation to during treatment time only and to enable system automation. During each treatment session, an initial image of the patient is acquired as soon as radiation starts and is compared with subsequent live images, which can be acquired at up to 30 fps by the real-time frame difference-based analysis software. When the error range exceeds the set criteria (δ(movement)) due to patient movement, a warning message is generated in the form of light and sound. The described procedure repeats automatically for each patient. A motion phantom, which operates by moving a distance of 0.1, 0.2, 0.3, 0.5, and 1.0 cm for 1 and 2 s, respectively, was used to evaluate the system performance. The authors measured optimal δ(movement) for clinical use, the minimum distance that can be detected with this system, and the response time of the whole system using a video analysis technique. The stability of the system in a linear accelerator unit was evaluated for a period of 6 months. As a result of the moving phantom test, the δ(movement) for detection of all simulated phantom motion except the 0.1 cm movement was determined to be 0.2% of total number of pixels in the initial image. The system can detect phantom motion as small as 0.2 cm. The measured response time from the detection of phantom movement to generation of the warning signal was 0.1 s. No significant functional disorder of the system was observed during the testing period. The VGRPM system has a convenient design, which synchronizes initiation of the analysis with a beam on/off signal from the treatment machine and may contribute to a reduction in treatment error due to patient motion and increase the accuracy of treatment dose delivery.

SU-F-BRE-05: Development and Evaluation of a Real-Time Robotic 6D Quality Assurance Phantom

DOE Office of Scientific and Technical Information (OSTI.GOV)

Belcher, AH; Liu, X; Grelewicz, Z

Purpose: A 6 degree-of-freedom robotic phantom capable of reproducing dynamic tumor motion in 6D was designed to more effectively match solid tumor movements throughout pre-treatment scanning and radiation therapy. With the abundance of optical and x-ray 6D real-time tumor tracking methodologies clinically available, and the substantial dosimetric consequences of failing to consider tumor rotation as well as translation, this work presents the development and evaluation of a 6D instrument with the facility to improve quality assurance. Methods: An in-house designed and built 6D robotic motion phantom was constructed following the so-called Stewart-Gough parallel kinematics platform archetype. The device was thenmore » controlled using an inverse kinematics formulation, and precise movements in all six degrees of freedom (X, Y, Z, pitch, roll, and yaw) as well as previously obtained cranial motion, were effectively executed. The robotic phantom movements were verified using a 15 fps 6D infrared marker tracking system (Polaris, NDI), and quantitatively compared to the input trajectory. Thus, the accuracy and repeatability of 6D motion was investigated and the phantom performance was characterized. Results: Evaluation of the 6D platform demonstrated translational RMSE values of 0.196 mm, 0.260 mm, and 0.101 mm over 20 mm in X and Y and 10 mm in Z, respectively, and rotational RMSE values of 0.068 degrees, 0.0611 degrees, and 0.095 degrees over 10 degrees of pitch, roll, and yaw, respectively. The robotic stage also effectively performed controlled 6D motions, as well as reproduced cranial trajectories over 15 minutes, with a maximal RMSE of 0.044 mm translationally and 0.036 degrees rotationally. Conclusion: This 6D robotic phantom has proven to be accurate under clinical standards and capable of reproducing tumor motion in 6D. Consequently, such a robotics device has the potential to serve as a more effective system for IGRT QA that involves both translational and rotational dimensions. Research was partially funded by NIH Grant T32 EB002103-21 from NIBIB. Contents are solely the responsibility of the authors and do not necessarily represent the official views of the NIBIB or NIH.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shafer, Morgan W; Battaglia, D. J.; Unterberg, Ezekial A

A new tangential 2D Soft X-Ray Imaging System (SXRIS) is being designed to examine the edge magnetic island structure in the lower X-point region of DIII-D. A synthetic diagnostic calculation coupled to 3D emissivity estimates is used to generate phantom images. Phillips-Tikhonov regularization is used to invert the phantom images for comparison to the original emissivity model. Noise level, island size, and equilibrium accuracy are scanned to assess the feasibility of detecting edge island structures. Models of typical DIII-D discharges indicate integration times > 1 ms with accurate equilibrium reconstruction are needed for small island (< 3 cm) detection.

An externally and internally deformable, programmable lung motion phantom

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheung, Yam; Sawant, Amit, E-mail: amit.sawant@utsouthwestern.edu

Purpose: Most clinically deployed strategies for respiratory motion management in lung radiotherapy (e.g., gating and tracking) use external markers that serve as surrogates for tumor motion. However, typical lung phantoms used to validate these strategies are based on a rigid exterior and a rigid or a deformable-interior. Such designs do not adequately represent respiration because the thoracic anatomy deforms internally as well as externally. In order to create a closer approximation of respiratory motion, the authors describe the construction and experimental testing of an externally as well as internally deformable, programmable lung phantom. Methods: The outer shell of a commerciallymore » available lung phantom (RS-1500, RSD, Inc.) was used. The shell consists of a chest cavity with a flexible anterior surface, and embedded vertebrae, rib-cage and sternum. A custom-made insert was designed using a piece of natural latex foam block. A motion platform was programmed with sinusoidal and ten patient-recorded lung tumor trajectories. The platform was used to drive a rigid foam “diaphragm” that compressed/decompressed the phantom interior. Experimental characterization comprised of determining the reproducibility and the external–internal correlation of external and internal marker trajectories extracted from kV x-ray fluoroscopy. Experiments were conducted to illustrate three example applications of the phantom—(i) validating the geometric accuracy of the VisionRT surface photogrammetry system; (ii) validating an image registration tool, NiftyReg; and (iii) quantifying the geometric error due to irregular motion in four-dimensional computed tomography (4DCT). Results: The phantom correctly reproduced sinusoidal and patient-derived motion, as well as realistic respiratory motion-related effects such as hysteresis. The reproducibility of marker trajectories over multiple runs for sinusoidal as well as patient traces, as characterized by fluoroscopy, was within 0.25 mm RMS error. The motion trajectories of internal and external radio-opaque markers as measured by fluoroscopy were found to be highly correlated (R > 0.95). Using the phantom, it was demonstrated that the motion trajectories of regions-of-interest on the surface as measured by VisionRT are highly consistent with corresponding fluoroscopically acquired surface marker trajectories, with RMS errors within 0.26 mm. Furthermore, it was shown that the trajectories of external and internal marker trajectories derived from NiftyReg deformation vector fields were within 1 mm root mean square errors comparing to trajectories obtained by segmenting markers from individual fluoro frames. Finally, it was shown that while 4DCT can be used to localize internal markers for sinusoidal motion with reasonable accuracy, the localization error increases significantly (by a factor of ∼2) in the presence of cycle-to-cycle variations that are observed in patient-derived respiratory motion. Conclusions: The authors have developed a realistic externally and internally deformable, programmable lung phantom that will serve as a valuable tool for clinical and investigational motion management studies in thoracic and abdominal radiation therapies.« less

An assembly-type master-slave catheter and guidewire driving system for vascular intervention.

PubMed

Cha, Hyo-Jeong; Yi, Byung-Ju; Won, Jong Yun

2017-01-01

Current vascular intervention inevitably exposes a large amount of X-ray to both an operator and a patient during the procedure. The purpose of this study is to propose a new catheter driving system which assists the operator in aspects of less X-ray exposure and convenient user interface. For this, an assembly-type 4-degree-of-freedom master-slave system was designed and tested to verify the efficiency. First, current vascular intervention procedures are analyzed to develop a new robotic procedure that enables us to use conventional vascular intervention devices such as catheter and guidewire which are commercially available in the market. Some parts of the slave robot which contact the devices were designed to be easily assembled and dissembled from the main body of the slave robot for sterilization. A master robot is compactly designed to conduct insertion and rotational motion and is able to switch from the guidewire driving mode to the catheter driving mode or vice versa. A phantom resembling the human arteries was developed, and the master-slave robotic system is tested using the phantom. The contact force of the guidewire tip according to the shape of the arteries is measured and reflected to the user through the master robot during the phantom experiment. This system can drastically reduce radiation exposure by replacing human effort by a robotic system for high radiation exposure procedures. Also, benefits of the proposed robot system are low cost by employing currently available devices and easy human interface.

Initial testing of a 3D printed perfusion phantom using digital subtraction angiography

NASA Astrophysics Data System (ADS)

Wood, Rachel P.; Khobragade, Parag; Ying, Leslie; Snyder, Kenneth; Wack, David; Bednarek, Daniel R.; Rudin, Stephen; Ionita, Ciprian N.

2015-03-01

Perfusion imaging is the most applied modality for the assessment of acute stroke. Parameters such as Cerebral Blood Flow (CBF), Cerebral Blood volume (CBV) and Mean Transit Time (MTT) are used to distinguish the tissue infarct core and ischemic penumbra. Due to lack of standardization these parameters vary significantly between vendors and software even when provided with the same data set. There is a critical need to standardize the systems and make them more reliable. We have designed a uniform phantom to test and verify the perfusion systems. We implemented a flow loop with different flow rates (250, 300, 350 ml/min) and injected the same amount of contrast. The images of the phantom were acquired using a Digital Angiographic system. Since this phantom is uniform, projection images obtained using DSA is sufficient for initial validation. To validate the phantom we measured the contrast concentration at three regions of interest (arterial input, venous output, perfused area) and derived time density curves (TDC). We then calculated the maximum slope, area under the TDCs and flow. The maximum slope calculations were linearly increasing with increase in flow rate, the area under the curve decreases with increase in flow rate. There was 25% error between the calculated flow and measured flow. The derived TDCs were clinically relevant and the calculated flow, maximum slope and areas under the curve were sensitive to the measured flow. We have created a systematic way to calibrate existing perfusion systems and assess their reliability.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rickey, Daniel; Sasaki, David; Dubey, Arbind

Purpose: Three-dimensional printing has been implemented at our institution to create customized treatment accessories including shielding and bolus. In order to effectively use 3D printing, the topography of the patient must first be acquired. To this end, we have evaluated a low-cost structured-light 3D scanner in order to assess the clinical viability of this technology. Methods: For ease of use, the scanner (3D Systems, Sense 3D Scanner) was mounted in a simple gantry that guided its motion and maintained an optimum distance between the scanner and the object. To characterise the spatial accuracy of the scanner, we used a geometricmore » phantom and an anthropomorphic head phantom. The geometric phantom was machined from plastic and had overall dimensions of 24 cm by 15 cm and included a hemispherical and a tetrahedron protrusion roughly the dimensions of an average forehead and nose respectively. Meshes acquired by the optical scanner were compared to meshes generated from high-resolution CT images. Results: Scans were acquired in under one minute. Most of the optical scans contained noticeable artefacts although in most instances these were considered minor. Using an algorithm that calculated distances between the two meshes, we found most of the optical scanner measurements agreed with those from CT to within about 1 mm for the geometric phantom and to within about 2 mm for the head phantom. Conclusion: In summary, we deemed this scanner to be clinically acceptable and it has been used to design treatment accessories for several skin cancer patients.« less

Whole body counter calibration using Monte Carlo modeling with an array of phantom sizes based on national anthropometric reference data

NASA Astrophysics Data System (ADS)

Shypailo, R. J.; Ellis, K. J.

2011-05-01

During construction of the whole body counter (WBC) at the Children's Nutrition Research Center (CNRC), efficiency calibration was needed to translate acquired counts of 40K to actual grams of potassium for measurement of total body potassium (TBK) in a diverse subject population. The MCNP Monte Carlo n-particle simulation program was used to describe the WBC (54 detectors plus shielding), test individual detector counting response, and create a series of virtual anthropomorphic phantoms based on national reference anthropometric data. Each phantom included an outer layer of adipose tissue and an inner core of lean tissue. Phantoms were designed for both genders representing ages 3.5 to 18.5 years with body sizes from the 5th to the 95th percentile based on body weight. In addition, a spherical surface source surrounding the WBC was modeled in order to measure the effects of subject mass on room background interference. Individual detector measurements showed good agreement with the MCNP model. The background source model came close to agreement with empirical measurements, but showed a trend deviating from unity with increasing subject size. Results from the MCNP simulation of the CNRC WBC agreed well with empirical measurements using BOMAB phantoms. Individual detector efficiency corrections were used to improve the accuracy of the model. Nonlinear multiple regression efficiency calibration equations were derived for each gender. Room background correction is critical in improving the accuracy of the WBC calibration.

Development and validation of a biologically realistic tissue-mimicking material for photoacoustics and other bimodal optical-acoustic modalities

NASA Astrophysics Data System (ADS)

Vogt, William C.; Jia, Congxian; Wear, Keith A.; Garra, Brian S.; Pfefer, T. Joshua

2017-03-01

Recent years have seen rapid development of hybrid optical-acoustic imaging modalities with broad applications in research and clinical imaging, including photoacoustic tomography (PAT), photoacoustic microscopy, and ultrasound-modulated optical tomography. Tissue-mimicking phantoms are an important tool for objectively and quantitatively simulating in vivo imaging system performance. However, no standard tissue phantoms exist for such systems. One major challenge is the development of tissue-mimicking materials (TMMs) that are both highly stable and possess biologically realistic properties. To address this need, we have explored the use of various formulations of PVC plastisol (PVCP) based on varying mixtures of several liquid plasticizers. We developed a custom PVCP formulation with optical absorption and scattering coefficients, speed of sound, and acoustic attenuation that are tunable and tissue-relevant. This TMM can simulate different tissue compositions and offers greater mechanical strength than hydrogels. Optical properties of PVCP samples with varying composition were characterized using integrating sphere spectrophotometry and the inverse adding-doubling method. Acoustic properties were determined using a broadband pulse-transmission technique. To demonstrate the utility of this bimodal TMM, we constructed an image quality phantom designed to enable quantitative evaluation of PAT spatial resolution. The phantom was imaged using a custom combined PAT-ultrasound imaging system. Results indicated that this more biologically realistic TMM produced performance trends not captured in simpler liquid phantoms. In the future, this TMM may be broadly utilized for performance evaluation of optical, acoustic, and hybrid optical-acoustic imaging systems.

Design of dual multiple aperture devices for dynamical fluence field modulated CT.

PubMed

Mathews, Aswin John; Tilley, Steven; Gang, Grace; Kawamoto, Satomi; Zbijewski, Wojciech; Siewerdsen, Jeffrey H; Levinson, Reuven; Webster Stayman, J

2016-07-01

A Multiple Aperture Device (MAD) is a novel x-ray beam modulator that uses binary filtration on a fine scale to spatially modulate an x-ray beam. Using two MADs in series enables a large variety of fluence profiles by shifting the MADS relative to each other. This work details the design and control of dual MADs for a specific class of desired fluence patterns. Specifically, models of MAD operation are integrated into a best fit objective followed by CMA-ES optimization. To illustrate this framework we demonstrate the design process for an abdominal phantom with the goal of uniform detected signal. Achievable fluence profiles show good agreement with target fluence profiles, and the ability to flatten projections when a phantom is scanned is demonstrated. Simulated data reconstruction using traditional tube current modulation (TCM) and MAD filtering with TCM are investigated with the dual MAD system demonstrating more uniformity in noise and illustrating the potential for dose reduction under a maximum noise level constraint.

Evaluation of EIT system performance.

PubMed

Yasin, Mamatjan; Böhm, Stephan; Gaggero, Pascal O; Adler, Andy

2011-07-01

An electrical impedance tomography (EIT) system images internal conductivity from surface electrical stimulation and measurement. Such systems necessarily comprise multiple design choices from cables and hardware design to calibration and image reconstruction. In order to compare EIT systems and study the consequences of changes in system performance, this paper describes a systematic approach to evaluate the performance of the EIT systems. The system to be tested is connected to a saline phantom in which calibrated contrasting test objects are systematically positioned using a position controller. A set of evaluation parameters are proposed which characterize (i) data and image noise, (ii) data accuracy, (iii) detectability of single contrasts and distinguishability of multiple contrasts, and (iv) accuracy of reconstructed image (amplitude, resolution, position and ringing). Using this approach, we evaluate three different EIT systems and illustrate the use of these tools to evaluate and compare performance. In order to facilitate the use of this approach, all details of the phantom, test objects and position controller design are made publicly available including the source code of the evaluation and reporting software.

Wellbore manufacturing processes for in situ heat treatment processes

DOEpatents

Davidson, Ian Alexander; Geddes, Cameron James; Rudolf, Randall Lynn; Selby, Bruce Allen; MacDonald, Duncan Charles

2012-12-11

A method includes making coiled tubing at a coiled tubing manufacturing unit coupled to a coiled tubing transportation system. One or more coiled tubing reels are transported from the coiled tubing manufacturing unit to one or more moveable well drilling systems using the coiled tubing transportation system. The coiled tubing transportation system runs from the tubing manufacturing unit to one or more movable well drilling systems, and then back to the coiled tubing manufacturing unit.

Tunable graded rod laser assembly

NASA Technical Reports Server (NTRS)

AuYeung, John C. (Inventor)

1985-01-01

A tunable laser assembly including a pair of radially graded indexed optical segments aligned to focus the laser to form an external resonant cavity with an optical axis, the respective optical segments are retativity moveable along the optical axis and provide a variable et aion gap sufficient to permit variable tuning of the laser wavelength without altering the effective length of the resonant cavity. The gap also include a saturable absorbing material providing a passive mode-locking of the laser.

Field of View Requirements for Carrier Landing Training

DTIC Science & Technology

1980-06-01

descent is guided by the Fresnel Lens Optical Landing System,(FLOLS) which displays a vertically moveable center iight beam (the " meatball ") which...must be kept aligned with rows of stationary horizontal lights. When the aircraft is above or below the correct glideslope, the meatball is seen as above...or below the horizontal reference lights. If the pilot is viewing a centered meatball , and if the aircraft has the correct AOA, the tailhook will be

KSC-2009-1567

NASA Image and Video Library

2009-02-12

CAPE CANAVERAL, Fla. – An aerial view of a mobile launcher platform that is parked in the Launch Complex 39 Area at NASA's Kennedy Space Center in Florida. The platform, which is a moveable base for the launch of space shuttle, is a two-story steel structure 25 feet high, 160 feet long and 135 feet wide. It is constructed of welded steel up to 6 inches thick. The platform rests on six 22-foot-tall pedestals. Photo credit: NASA/Kim Shiflett

KSC-2009-1566

NASA Image and Video Library

2009-02-12

CAPE CANAVERAL, Fla. – An aerial view of a mobile launcher platform that is parked in the Launch Complex 39 Area at NASA's Kennedy Space Center in Florida. The platform, which is a moveable base for the launch of space shuttle, is a two-story steel structure 25 feet high, 160 feet long and 135 feet wide. It is constructed of welded steel up to 6 inches thick. The platform rests on six 22-foot-tall pedestals. Photo credit: NASA/Kim Shiflett

KSC-2009-1568

NASA Image and Video Library

2009-02-12

CAPE CANAVERAL, Fla. – An aerial view of a mobile launcher platform that is parked in the Launch Complex 39 Area at NASA's Kennedy Space Center in Florida. The platform, which is a moveable base for the launch of space shuttle, is a two-story steel structure 25 feet high, 160 feet long and 135 feet wide. It is constructed of welded steel up to 6 inches thick. The platform rests on six 22-foot-tall pedestals. Photo credit: NASA/Kim Shiflett

Modular radiochemistry synthesis system

DOEpatents

Satyamurthy, Nagichettiar; Barrio, Jorge R.; Amarasekera, Bernard; Van Dam, Michael R.; Olma, Sebastian; Williams, Dirk; Eddings, Mark; Shen, Clifton Kwang-Fu

2016-11-01

A modular chemical production system includes multiple modules for performing a chemical reaction, particularly of radiochemical compounds, from a remote location. One embodiment comprises a reaction vessel including a moveable heat source with the position thereof relative to the reaction vessel being controllable from a remote position. Alternatively the heat source may be fixed in location and the reaction vial is moveable into and out of the heat source. The reaction vessel has one or more sealing plugs, the positioning of which in relationship to the reaction vessel is controllable from a remote position. Also the one or more reaction vessel sealing plugs can include one or more conduits there through for delivery of reactants, gases at atmospheric or an elevated pressure, inert gases, drawing a vacuum and removal of reaction end products to and from the reaction vial, the reaction vial with sealing plug in position being operable at elevated pressures. The modular chemical production system is assembled from modules which can each include operating condition sensors and controllers configured for monitoring and controlling the individual modules and the assembled system from a remote position. Other modules include, but are not limited to a Reagent Storage and Delivery Module, a Cartridge Purification Module, a Microwave Reaction Module, an External QC/Analysis/Purification Interface Module, an Aliquotting Module, an F-18 Drying Module, a Concentration Module, a Radiation Counting Module, and a Capillary Reactor Module.

Modular radiochemistry synthesis system

DOEpatents

Satyamurthy, Nagichettiar; Barrio, Jorge R.; Amarasekera, Bernard; Van Dam, R. Michael; Olma, Sebastian; Williams, Dirk; Eddings, Mark; Shen, Clifton Kwang-Fu

2015-12-15

A modular chemical production system includes multiple modules for performing a chemical reaction, particularly of radiochemical compounds, from a remote location. One embodiment comprises a reaction vessel including a moveable heat source with the position thereof relative to the reaction vessel being controllable from a remote position. Alternatively the heat source may be fixed in location and the reaction vial is moveable into and out of the heat source. The reaction vessel has one or more sealing plugs, the positioning of which in relationship to the reaction vessel is controllable from a remote position. Also the one or more reaction vessel sealing plugs can include one or more conduits there through for delivery of reactants, gases at atmospheric or an elevated pressure, inert gases, drawing a vacuum and removal of reaction end products to and from the reaction vial, the reaction vial with sealing plug in position being operable at elevated pressures. The modular chemical production system is assembled from modules which can each include operating condition sensors and controllers configured for monitoring and controlling the individual modules and the assembled system from a remote position. Other modules include, but are not limited to a Reagent Storage and Delivery Module, a Cartridge Purification Module, a Microwave Reaction Module, an External QC/Analysis/Purification Interface Module, an Aliquotting Module, an F-18 Drying Module, a Concentration Module, a Radiation Counting Module, and a Capillary Reactor Module.

Modular radiochemistry synthesis system

DOEpatents

Satyamurthy, Nagichettiar; Barrio, Jorge R; Amarasekera, Bernard; Van Dam, R. Michael; Olma, Sebastian; Williams, Dirk; Eddings, Mark A; Shen, Clifton Kwang-Fu

2015-02-10

A modular chemical production system includes multiple modules for performing a chemical reaction, particularly of radiochemical compounds, from a remote location. One embodiment comprises a reaction vessel including a moveable heat source with the position thereof relative to the reaction vessel being controllable from a remote position. Alternatively the heat source may be fixed in location and the reaction vial is moveable into and out of the heat source. The reaction vessel has one or more sealing plugs, the positioning of which in relationship to the reaction vessel is controllable from a remote position. Also the one or more reaction vessel sealing plugs can include one or more conduits there through for delivery of reactants, gases at atmospheric or an elevated pressure, inert gases, drawing a vacuum and removal of reaction end products to and from the reaction vial, the reaction vial with sealing plug in position being operable at elevated pressures. The modular chemical production system is assembled from modules which can each include operating condition sensors and controllers configured for monitoring and controlling the individual modules and the assembled system from a remote position. Other modules include, but are not limited to a Reagent Storage and Delivery Module, a Cartridge Purification Module, a Microwave Reaction Module, an External QC/Analysis/Purification Interface Module, an Aliquotting Module, an F-18 Drying Module, a Concentration Module, a Radiation Counting Module, and a Capillary Reactor Module.

KENNEDY SPACE CENTER, FLA. - At the Astrotech Space Operations processing facilities near KSC, workers check the moveable pallet holding NASA’s MESSENGER spacecraft. MESSENGER - short for MErcury Surface, Space ENvironment, GEochemistry and Ranging - will be taken into a high bay clean room and employees of the Johns Hopkins University Applied Physics Laboratory, builders of the spacecraft, will perform an initial state-of-health check. Then processing for launch can begin, including checkout of the power systems, communications systems and control systems. The thermal blankets will also be attached for flight. MESSENGER will be launched May 11 on a six-year mission aboard a Boeing Delta II rocket. Liftoff is targeted for 2:26 a.m. EDT on Tuesday, May 11.

NASA Image and Video Library

2004-03-10

KENNEDY SPACE CENTER, FLA. - At the Astrotech Space Operations processing facilities near KSC, workers check the moveable pallet holding NASA’s MESSENGER spacecraft. MESSENGER - short for MErcury Surface, Space ENvironment, GEochemistry and Ranging - will be taken into a high bay clean room and employees of the Johns Hopkins University Applied Physics Laboratory, builders of the spacecraft, will perform an initial state-of-health check. Then processing for launch can begin, including checkout of the power systems, communications systems and control systems. The thermal blankets will also be attached for flight. MESSENGER will be launched May 11 on a six-year mission aboard a Boeing Delta II rocket. Liftoff is targeted for 2:26 a.m. EDT on Tuesday, May 11.

Novel tissue phantom for testing a dual-modality diagnostic system: time-resolved fluorescence spectroscopy and high frequency ultrasound

NASA Astrophysics Data System (ADS)

Sun, Yang; Liao, Kuo-Chih; Sun, Yinghua; Park, Jesung; Marcu, Laura

2008-02-01

A unique tissue phantom is reported here that mimics the optical and acoustical properties of biological tissue and enables testing and validation of a dual-modality clinical diagnostic system combining time-resolved laser-induced fluorescence spectroscopy (TR-LIFS) and ultrasound backscatter microscopy (UBM). The phantom consisted of contrast agents including silicon dioxide particles with a range of diameters from 0.5 to 10 μm acting as optical and acoustical scatterers, and FITC-conjugated dextran mimicking the endogenous fluorophore in tissue. The agents were encapsulated in a polymer bead attached to the end of an optical fiber with a 200 μm diameter using a UV-induced polymerization technique. A set of beads with fibers were then implanted into a gel-based matrix with controlled patterns including a design with lateral distribution and a design with successively changing depth. The configuration presented here allowed the validation of the hybrid fluorescence spectroscopic and ultrasonic system by detecting the lateral and depth distribution of the contrast agents, as well as for coregistration of the ultrasonic image with spectroscopic data. In addition, the depth of the beads in the gel matrix was changed to explore the effect of different concentration ratio of the mixture on the fluorescence signal emitted.

Design and Characterization of an Acoustically and Structurally Matched 3-D-Printed Model for Transcranial Ultrasound Imaging.

PubMed

Bai, Chen; Ji, Meiling; Bouakaz, Ayache; Zong, Yujin; Wan, Mingxi

2018-05-01

For investigating human transcranial ultrasound imaging (TUI) through the temporal bone, an intact human skull is needed. Since it is complex and expensive to obtain one, it requires that experiments are performed without excision or abrasion of the skull. Besides, to mimic blood circulation for the vessel target, cellulose tubes generally fit the vessel simulation with straight linear features. These issues, which limit experimental studies, can be overcome by designing a 3-D-printed skull model with acoustic and dimensional properties that match a real skull and a vessel model with curve and bifurcation. First, the optimal printing material which matched a real skull in terms of the acoustic attenuation coefficient and sound propagation velocity was identified at 2-MHz frequency, i.e., 7.06 dB/mm and 2168.71 m/s for the skull while 6.98 dB/mm and 2114.72 m/s for the printed material, respectively. After modeling, the average thickness of the temporal bone in the printed skull was about 1.8 mm, while it was to 1.7 mm in the real skull. Then, a vascular phantom was designed with 3-D-printed vessels of low acoustic attenuation (0.6 dB/mm). It was covered with a porcine brain tissue contained within a transparent polyacrylamide gel. After characterizing the acoustic consistency, based on the designed skull model and vascular phantom, vessels with inner diameters of 1 and 0.7 mm were distinguished by resolution enhanced imaging with low frequency. Measurements and imaging results proved that the model and phantom are authentic and viable alternatives, and will be of interest for TUI, high intensity focused ultrasound, or other therapy studies.

Sensitivity studies of beam directionality, beam size, and neutron spectrum for a fission converter-based epithermal neutron beam for boron neutron capture therapy.

PubMed

Sakamoto, S; Kiger, W S; Harling, O K

1999-09-01

Sensitivity studies of epithermal neutron beam performance in boron neutron capture therapy are presented for realistic neutron beams with varying filter/moderator and collimator/delimiter designs to examine the relative importance of neutron beam spectrum, directionality, and size. Figures of merit for in-air and in-phantom beam performance are calculated via the Monte Carlo technique for different well-optimized designs of a fission converter-based epithermal neutron beam with head phantoms as the irradiation target. It is shown that increasing J/phi, a measure of beam directionality, does not always lead to corresponding monotonic improvements in beam performance. Due to the relatively low significance, for most configurations, of its effect on in-phantom performance and the large intensity losses required to produce beams with very high J/phi, beam directionality should not be considered an important figure of merit in epithermal neutron beam design except in terms of its consequences on patient positioning and collateral dose. Hardening the epithermal beam spectrum, while maintaining the specific fast neutron dose well below the inherent hydrogen capture dose, improves beam penetration and advantage depth and, as a desirable by-product, significantly increases beam intensity. Beam figures of merit are shown to be strongly dependent on beam size relative to target size. Beam designs with J/phi approximately 0.65-0.7, specific fast neutron doses of 2-2.6x10(-13) Gy cm2/n and beam sizes equal to or larger than the size of the head target produced the deepest useful penetration, highest therapeutic ratios, and highest intensities.

Dose distribution verification for GYN brachytherapy using EBT Gafchromic film and TG-43 calculation.

PubMed

Gholami, Somayeh; Mirzaei, Hamid Reza; Jabbary Arfaee, Ali; Jaberi, Ramin; Nedaie, Hassan Ali; Rabi Mahdavi, Seied; Rajab Bolookat, Eftekhar; Meigooni, Ali S

2016-01-01

Verification of dose distributions for gynecological (GYN) brachytherapy implants using EBT Gafchromic film. One major challenge in brachytherapy is to verify the accuracy of dose distributions calculated by a treatment planning system. A new phantom was designed and fabricated using 90 slabs of 18 cm × 16 cm × 0.2 cm Perspex to accommodate a tandem and Ovoid assembly, which is normally used for GYN brachytherapy treatment. This phantom design allows the use of EBT Gafchromic films for dosimetric verification of GYN implants with a cobalt-60 HDR system or a LDR Cs-137 system. Gafchromic films were exposed using a plan that was designed to deliver 1.5 Gy of dose to 0.5 cm distance from the lateral surface of ovoids from a pair of ovoid assembly that was used for treatment vaginal cuff. For a quantitative analysis of the results for both LDR and HDR systems, the measured dose values at several points of interests were compared with the calculated data from a commercially available treatment planning system. This planning system was utilizing the TG-43 formalism and parameters for calculation of dose distributions around a brachytherapy implant. The results of these investigations indicated that the differences between the calculated and measured data at different points were ranging from 2.4% to 3.8% for the LDR Cs-137 and HDR Co-60 systems, respectively. The EBT Gafchromic films combined with the newly designed phantom could be utilized for verification of the dose distributions around different GYN implants treated with either LDR or HDR brachytherapy procedures.

Automatic Exposure Control Systems Designed to Maintain Constant Image Noise: Effects on Computed Tomography Dose and Noise Relative to Clinically Accepted Technique Charts

PubMed Central

Favazza, Christopher P.; Yu, Lifeng; Leng, Shuai; Kofler, James M.; McCollough, Cynthia H.

2015-01-01

Objective To compare computed tomography dose and noise arising from use of an automatic exposure control (AEC) system designed to maintain constant image noise as patient size varies with clinically accepted technique charts and AEC systems designed to vary image noise. Materials and Methods A model was developed to describe tube current modulation as a function of patient thickness. Relative dose and noise values were calculated as patient width varied for AEC settings designed to yield constant or variable noise levels and were compared to empirically derived values used by our clinical practice. Phantom experiments were performed in which tube current was measured as a function of thickness using a constant-noise-based AEC system and the results were compared with clinical technique charts. Results For 12-, 20-, 28-, 44-, and 50-cm patient widths, the requirement of constant noise across patient size yielded relative doses of 5%, 14%, 38%, 260%, and 549% and relative noises of 435%, 267%, 163%, 61%, and 42%, respectively, as compared with our clinically used technique chart settings at each respective width. Experimental measurements showed that a constant noise–based AEC system yielded 175% relative noise for a 30-cm phantom and 206% relative dose for a 40-cm phantom compared with our clinical technique chart. Conclusions Automatic exposure control systems that prescribe constant noise as patient size varies can yield excessive noise in small patients and excessive dose in obese patients compared with clinically accepted technique charts. Use of noise-level technique charts and tube current limits can mitigate these effects. PMID:25938214

The development and verification of a highly accurate collision prediction model for automated noncoplanar plan delivery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, Victoria Y.; Tran, Angelia; Nguyen, Dan

2015-11-15

Purpose: Significant dosimetric benefits had been previously demonstrated in highly noncoplanar treatment plans. In this study, the authors developed and verified an individualized collision model for the purpose of delivering highly noncoplanar radiotherapy and tested the feasibility of total delivery automation with Varian TrueBeam developer mode. Methods: A hand-held 3D scanner was used to capture the surfaces of an anthropomorphic phantom and a human subject, which were positioned with a computer-aided design model of a TrueBeam machine to create a detailed virtual geometrical collision model. The collision model included gantry, collimator, and couch motion degrees of freedom. The accuracy ofmore » the 3D scanner was validated by scanning a rigid cubical phantom with known dimensions. The collision model was then validated by generating 300 linear accelerator orientations corresponding to 300 gantry-to-couch and gantry-to-phantom distances, and comparing the corresponding distance measurements to their corresponding models. The linear accelerator orientations reflected uniformly sampled noncoplanar beam angles to the head, lung, and prostate. The distance discrepancies between measurements on the physical and virtual systems were used to estimate treatment-site-specific safety buffer distances with 0.1%, 0.01%, and 0.001% probability of collision between the gantry and couch or phantom. Plans containing 20 noncoplanar beams to the brain, lung, and prostate optimized via an in-house noncoplanar radiotherapy platform were converted into XML script for automated delivery and the entire delivery was recorded and timed to demonstrate the feasibility of automated delivery. Results: The 3D scanner measured the dimension of the 14 cm cubic phantom within 0.5 mm. The maximal absolute discrepancy between machine and model measurements for gantry-to-couch and gantry-to-phantom was 0.95 and 2.97 cm, respectively. The reduced accuracy of gantry-to-phantom measurements was attributed to phantom setup errors due to the slightly deformable and flexible phantom extremities. The estimated site-specific safety buffer distance with 0.001% probability of collision for (gantry-to-couch, gantry-to-phantom) was (1.23 cm, 3.35 cm), (1.01 cm, 3.99 cm), and (2.19 cm, 5.73 cm) for treatment to the head, lung, and prostate, respectively. Automated delivery to all three treatment sites was completed in 15 min and collision free using a digital Linac. Conclusions: An individualized collision prediction model for the purpose of noncoplanar beam delivery was developed and verified. With the model, the study has demonstrated the feasibility of predicting deliverable beams for an individual patient and then guiding fully automated noncoplanar treatment delivery. This work motivates development of clinical workflows and quality assurance procedures to allow more extensive use and automation of noncoplanar beam geometries.« less

The development and verification of a highly accurate collision prediction model for automated noncoplanar plan delivery.

PubMed

Yu, Victoria Y; Tran, Angelia; Nguyen, Dan; Cao, Minsong; Ruan, Dan; Low, Daniel A; Sheng, Ke

2015-11-01

Significant dosimetric benefits had been previously demonstrated in highly noncoplanar treatment plans. In this study, the authors developed and verified an individualized collision model for the purpose of delivering highly noncoplanar radiotherapy and tested the feasibility of total delivery automation with Varian TrueBeam developer mode. A hand-held 3D scanner was used to capture the surfaces of an anthropomorphic phantom and a human subject, which were positioned with a computer-aided design model of a TrueBeam machine to create a detailed virtual geometrical collision model. The collision model included gantry, collimator, and couch motion degrees of freedom. The accuracy of the 3D scanner was validated by scanning a rigid cubical phantom with known dimensions. The collision model was then validated by generating 300 linear accelerator orientations corresponding to 300 gantry-to-couch and gantry-to-phantom distances, and comparing the corresponding distance measurements to their corresponding models. The linear accelerator orientations reflected uniformly sampled noncoplanar beam angles to the head, lung, and prostate. The distance discrepancies between measurements on the physical and virtual systems were used to estimate treatment-site-specific safety buffer distances with 0.1%, 0.01%, and 0.001% probability of collision between the gantry and couch or phantom. Plans containing 20 noncoplanar beams to the brain, lung, and prostate optimized via an in-house noncoplanar radiotherapy platform were converted into XML script for automated delivery and the entire delivery was recorded and timed to demonstrate the feasibility of automated delivery. The 3D scanner measured the dimension of the 14 cm cubic phantom within 0.5 mm. The maximal absolute discrepancy between machine and model measurements for gantry-to-couch and gantry-to-phantom was 0.95 and 2.97 cm, respectively. The reduced accuracy of gantry-to-phantom measurements was attributed to phantom setup errors due to the slightly deformable and flexible phantom extremities. The estimated site-specific safety buffer distance with 0.001% probability of collision for (gantry-to-couch, gantry-to-phantom) was (1.23 cm, 3.35 cm), (1.01 cm, 3.99 cm), and (2.19 cm, 5.73 cm) for treatment to the head, lung, and prostate, respectively. Automated delivery to all three treatment sites was completed in 15 min and collision free using a digital Linac. An individualized collision prediction model for the purpose of noncoplanar beam delivery was developed and verified. With the model, the study has demonstrated the feasibility of predicting deliverable beams for an individual patient and then guiding fully automated noncoplanar treatment delivery. This work motivates development of clinical workflows and quality assurance procedures to allow more extensive use and automation of noncoplanar beam geometries.

The development and verification of a highly accurate collision prediction model for automated noncoplanar plan delivery

PubMed Central

Yu, Victoria Y.; Tran, Angelia; Nguyen, Dan; Cao, Minsong; Ruan, Dan; Low, Daniel A.; Sheng, Ke

2015-01-01

Purpose: Significant dosimetric benefits had been previously demonstrated in highly noncoplanar treatment plans. In this study, the authors developed and verified an individualized collision model for the purpose of delivering highly noncoplanar radiotherapy and tested the feasibility of total delivery automation with Varian TrueBeam developer mode. Methods: A hand-held 3D scanner was used to capture the surfaces of an anthropomorphic phantom and a human subject, which were positioned with a computer-aided design model of a TrueBeam machine to create a detailed virtual geometrical collision model. The collision model included gantry, collimator, and couch motion degrees of freedom. The accuracy of the 3D scanner was validated by scanning a rigid cubical phantom with known dimensions. The collision model was then validated by generating 300 linear accelerator orientations corresponding to 300 gantry-to-couch and gantry-to-phantom distances, and comparing the corresponding distance measurements to their corresponding models. The linear accelerator orientations reflected uniformly sampled noncoplanar beam angles to the head, lung, and prostate. The distance discrepancies between measurements on the physical and virtual systems were used to estimate treatment-site-specific safety buffer distances with 0.1%, 0.01%, and 0.001% probability of collision between the gantry and couch or phantom. Plans containing 20 noncoplanar beams to the brain, lung, and prostate optimized via an in-house noncoplanar radiotherapy platform were converted into XML script for automated delivery and the entire delivery was recorded and timed to demonstrate the feasibility of automated delivery. Results: The 3D scanner measured the dimension of the 14 cm cubic phantom within 0.5 mm. The maximal absolute discrepancy between machine and model measurements for gantry-to-couch and gantry-to-phantom was 0.95 and 2.97 cm, respectively. The reduced accuracy of gantry-to-phantom measurements was attributed to phantom setup errors due to the slightly deformable and flexible phantom extremities. The estimated site-specific safety buffer distance with 0.001% probability of collision for (gantry-to-couch, gantry-to-phantom) was (1.23 cm, 3.35 cm), (1.01 cm, 3.99 cm), and (2.19 cm, 5.73 cm) for treatment to the head, lung, and prostate, respectively. Automated delivery to all three treatment sites was completed in 15 min and collision free using a digital Linac. Conclusions: An individualized collision prediction model for the purpose of noncoplanar beam delivery was developed and verified. With the model, the study has demonstrated the feasibility of predicting deliverable beams for an individual patient and then guiding fully automated noncoplanar treatment delivery. This work motivates development of clinical workflows and quality assurance procedures to allow more extensive use and automation of noncoplanar beam geometries. PMID:26520735

Fast resolution change in neutral helium atom microscopy

NASA Astrophysics Data System (ADS)

Flatabø, R.; Eder, S. D.; Ravn, A. K.; Samelin, B.; Greve, M. M.; Reisinger, T.; Holst, B.

2018-05-01

In neutral helium atom microscopy, a beam of atoms is scanned across a surface. Though still in its infancy, neutral helium microscopy has seen a rapid development over the last few years. The inertness and low energy of the helium atoms (less than 0.1 eV) combined with a very large depth of field and the fact that the helium atoms do not penetrate any solid material at low energies open the possibility for a non-destructive instrument that can measure topology on the nanoscale even on fragile and insulating surfaces. The resolution is determined by the beam spot size on the sample. Fast resolution change is an attractive property of a microscope because it allows different aspects of a sample to be investigated and makes it easier to identify specific features. However up till now it has not been possible to change the resolution of a helium microscope without breaking the vacuum and changing parts of the atom source. Here we present a modified source design, which allows fast, step wise resolution change. The basic design idea is to insert a moveable holder with a series of collimating apertures in front of the source, thus changing the effective source size of the beam and thereby the spot size on the surface and thus the microscope resolution. We demonstrate a design with 3 resolution steps. The number of resolution steps can easily be extended.

Organ doses for reference adult male and female undergoing computed tomography estimated by Monte Carlo simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Choonsik; Kim, Kwang Pyo; Long, Daniel

2011-03-15

Purpose: To develop a computed tomography (CT) organ dose estimation method designed to readily provide organ doses in a reference adult male and female for different scan ranges to investigate the degree to which existing commercial programs can reasonably match organ doses defined in these more anatomically realistic adult hybrid phantomsMethods: The x-ray fan beam in the SOMATOM Sensation 16 multidetector CT scanner was simulated within the Monte Carlo radiation transport code MCNPX2.6. The simulated CT scanner model was validated through comparison with experimentally measured lateral free-in-air dose profiles and computed tomography dose index (CTDI) values. The reference adult malemore » and female hybrid phantoms were coupled with the established CT scanner model following arm removal to simulate clinical head and other body region scans. A set of organ dose matrices were calculated for a series of consecutive axial scans ranging from the top of the head to the bottom of the phantoms with a beam thickness of 10 mm and the tube potentials of 80, 100, and 120 kVp. The organ doses for head, chest, and abdomen/pelvis examinations were calculated based on the organ dose matrices and compared to those obtained from two commercial programs, CT-EXPO and CTDOSIMETRY. Organ dose calculations were repeated for an adult stylized phantom by using the same simulation method used for the adult hybrid phantom. Results: Comparisons of both lateral free-in-air dose profiles and CTDI values through experimental measurement with the Monte Carlo simulations showed good agreement to within 9%. Organ doses for head, chest, and abdomen/pelvis scans reported in the commercial programs exceeded those from the Monte Carlo calculations in both the hybrid and stylized phantoms in this study, sometimes by orders of magnitude. Conclusions: The organ dose estimation method and dose matrices established in this study readily provides organ doses for a reference adult male and female for different CT scan ranges and technical parameters. Organ doses from existing commercial programs do not reasonably match organ doses calculated for the hybrid phantoms due to differences in phantom anatomy, as well as differences in organ dose scaling parameters. The organ dose matrices developed in this study will be extended to cover different technical parameters, CT scanner models, and various age groups.« less

SU-G-BRA-13: An Advanced Deformable Lung Phantom for Analyzing the Dosimetric Impact of Respiratory Motion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shin, D; Kang, S; Kim, D

2016-06-15

Purpose: The difference between three-dimensional (3D) and four-dimensional (4D) dose is affected by factors such as tumor size and motion. To quantitatively analyze the effects of these factors, a phantom that can independently control for each factor is required. The purpose of this study is to develop a deformable lung phantom with the above attributes and evaluate characteristics. Methods: A phantom was designed to simulate diaphragm motion with amplitude in the range 1 to 7 cm and various periods of regular breathing. To simulate different size tumors, tumors were produced by pouring liquid silicone into custom molds created by amore » 3D printer. The accuracy of phantom diaphragm motion was assessed using calipers and protractor. To control tumor motion, tumor trajectories were evaluated using 4D computed tomography (CT), and diaphragm-tumor correlation curve was calculated by curve fitting method. Three-dimensional dose and 4D dose were calculated and compared according to tumor motion. Results: The accuracy of phantom diaphragm motion was less than 1 mm. Maximum tumor motion amplitudes in the left-right and anterior-posterior directions were 0.08 and 0.12 cm, respectively, in a 10 cm{sup 3} tumor, and 0.06 and 0.27 cm, respectively, in a 90 cm{sup 3} tumor. The diaphragm-tumor correlation curve showed that tumor motion in the superior-inferior direction was increased with increasing diaphragm motion. In the 10 cm{sup 3} tumor, the tumor motion was larger than the 90 cm{sup 3} tumor. According to tumor motion, variation of dose difference between 3D and 4D was identified. Conclusion: The developed phantom can independently control factors such as tumor size and motion. In potentially, this phantom can be used to quantitatively analyze the dosimetric impact of respiratory motion according to the factors that influence the difference between 3D and 4D dose. This research was supported by the Mid-career Researcher Program through NRF funded by the Ministry of Science, ICT & Future Planning of Korea (NRF-2014R1A2A1A10050270) and by the Radiation Technology R&D program through the National Research Foundation of Korea funded by the Ministry of Science, ICT & Future Planning (No. 2013M2A2A7038291)« less

TU-AB-BRA-06: BEST IN PHYSICS (JOINT IMAGING-THERAPY): An MRI Compatible Externally and Internally Deformable Lung Motion Phantom for Multi-Modality IGRT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sabouri, P; Sawant, A; Arai, T

Purpose: MRI has become an attractive tool for tumor motion management. Current MR-compatible phantoms are only capable of reproducing translational motion. This study describes the construction and validation of a more realistic, MRI-compatible lung phantom that is deformable internally as well as externally. We demonstrate a radiotherapy application of this phantom by validating the geometric accuracy of the open-source deformable image registration software NiftyReg (UCL, UK). Methods: The outer shell of a commercially-available dynamic breathing torso phantom was filled with natural latex foam with eleven water tubes. A rigid foam cut-out served as the diaphragm. A high-precision programmable, in-house, MRI-compatiblemore » motion platform was used to drive the diaphragm. The phantom was imaged on a 3T scanner (Philips, Ingenia). Twenty seven tumor traces previously recorded from lung cancer patients were programmed into the phantom and 2D+t image sequences were acquired using a sparse-sampling sequence k-t BLAST (accn=3, resolution=0.66×0.66×5mm3; acquisition-time=110ms/slice). The geometric fidelity of the MRI-derived trajectories was validated against those obtained via fluoroscopy using the on board kV imager on a Truebeam linac. NiftyReg was used to perform frame by frame deformable image registration. The location of each marker predicted by using NiftyReg was compared with the values calculated by intensity-based segmentation on each frame. Results: In all cases, MR trajectories were within 1 mm of corresponding fluoroscopy trajectories. RMSE between centroid positions obtained from segmentation with those obtained by NiftyReg varies from 0.1 to 0.21 mm in the SI direction and 0.08 to 0.13 mm in the LR direction showing the high accuracy of deformable registration. Conclusion: We have successfully designed and demonstrated a phantom that can accurately reproduce deformable motion under a variety of imaging modalities including MRI, CT and x-ray fluodoscopy, making it an invaluable research tool for validating novel motion management strategies. This work was partially supported through research funding from National Institutes of Health (R01CA169102).« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mandapaka, A; Ghebremedhin, A; Farley, D

Purpose: To develop the methodology to evaluate the clinical performance of a Phase II Proton CT scanner Methods: Range errors on the order of 3%-5% constitute a major uncertainty in current charged particle treatment planning based on Hounsfield Unit (HU)-relative stopping power (RSP) calibration curves. Within our proton CT collaboration, we previously developed and built a Phase I proton CT scanner that provided a sensitive area of 9 cm (axial) × 18 cm (in-plane). This scanner served to get initial experience with this new treatment planning tool and to incorporate lessons learned into the next generation design. A Phase IImore » scanner was recently completed and is now undergoing initial performance testing. It will increase the proton acquisition rate and provide a larger detection area of 9 cm x 36 cm. We are now designing a comprehensive evaluation program to test the image quality, imaging dose, and range uncertainty associated with this scanner. The testing will be performed along the lines of AAPM TG 66. Results: In our discussion of the evaluation protocol we identified the following priorities. The image quality of proton CT images, in particular spatial resolution and low-density contrast discrimination, will be evaluated with the Catphan600 phantom. Initial testing showed that the Catphan uniformity phantom did not provide sufficient uniformity; it was thus replaced by a cylindrical water phantom. The imaging dose will be tested with a Catphan dose module, and compared to a typical cone beam CT dose for comparable image quality. Lastly, we developed a dedicated dosimetry range phantom based on the CIRS pediatric head phantom HN715. Conclusion: A formal evaluation of proton CT as a new tool for proton treatment planning is an important task. The availability of the new Phase II proton CT scanner will allow us to perform this task. This research is supported by the National Institute of Biomedical Imaging and Bioengineering of the NIH under award number R01EB013118. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ren, Liqiang; Wu, Di; Li, Yuhua

Purpose : X-ray fluorescence (XRF) is a promising technique with sufficient specificity and sensitivity for identifying and quantifying features in small samples containing high atomic number (Z) materials such as iodine, gadolinium, and gold. In this study, the feasibility of applying XRF to early breast cancer diagnosis and treatment is studied using a novel approach for three-dimensional (3D) x-ray fluorescence mapping (XFM) of gold nanoparticle (GNP)-loaded objects in a physical phantom at the technical level. Methods : All the theoretical analysis and experiments are conducted under the condition of using x-ray pencil beam and a compactly integrated x-ray spectrometer. Themore » penetrability of the fluorescence x-rays from GNPs is first investigated by adopting a combination of BR12 with 70 mm/50 mm in thickness on the excitation/emission path to mimic the possible position of tumor goldin vivo. Then, a physical phantom made of BR12 is designed to translate in 3D space with three precise linear stages and subsequently the step by step XFM scanning is performed. The experimental technique named as background subtraction is applied to isolate the gold fluorescence from each spectrum obtained by the spectrometer. Afterwards, the attenuations of both the incident primary x-ray beam with energies beyond the gold K-edge energy (80.725 keV) and the isolated gold K{sub α} fluorescence x-rays (65.99 –69.80 keV) acquired after background subtraction are well calibrated, and finally the unattenuated K{sub α} fluorescence counts are used to realize mapping reconstruction and to describe the linear relationship between gold fluorescence counts and corresponding concentration of gold solutions. Results : The penetration results show that the goldK{sub α} fluorescence x-rays have sufficient penetrability for this phantom study, and the reconstructed mapping results indicate that both the spatial distribution and relative concentration of GNPs within the designed BR12 phantom can be well identified and quantified. Conclusions : Although the XFM method in this investigation is still studied at the technical level and is not yet practical for routinein vivo mapping tasks with GNPs, the current penetrability measurements and phantom study strongly suggest the feasibility to establish and develop a 3D XFM system.« less

Planar oscillatory stirring apparatus

NASA Technical Reports Server (NTRS)

Wolf, Martin F. (Inventor)

1987-01-01

Apparatus (11) for applying planar oscillations to a container (13). Pressurized air (99) is supplied to a moveable slide plate (27) which employs arms (19) having an air bearing vent structure (29, 31) which allows the slide plate to float and to translate. The container (13) to be oscillated is secured to the upper surface of the slide plate (27). A motor (39) driven rotating eccentric shaft (59) loosely extends into a center hole bearing (37) of the slide plate (27) to cause the oscillations.

Moving Object Control System

NASA Technical Reports Server (NTRS)

Arndt, G. Dickey (Inventor); Carl, James R. (Inventor)

2001-01-01

A method is provided for controlling two objects relatively moveable with respect to each other. A plurality of receivers are provided for detecting a distinctive microwave signal from each of the objects and measuring the phase thereof with respect to a reference signal. The measured phase signal is used to determine a distance between each of the objects and each of the plurality of receivers. Control signals produced in response to the relative distances are used to control the position of the two objects.

Improved Estimates of Capital Formation in the National Health Expenditure Accounts

PubMed Central

Sensenig, Arthur L.; Donahoe, Gerald F.

2006-01-01

The National Health Expenditure Accounts (NHEA) were revised with the release of the 2004 estimates. The largest revision was the incorporation of a more comprehensive measure of investment in medical sector capital. The revision raised total health expenditures' share of gross domestic product (GDP) from 15.4 to 15.8 percent in 2003. The improved measure encompasses investment in moveable equipment and software, as well as expenditures for the construction of structures used by the medical sector. PMID:17290665

a Predator-Prey Model Based on the Fully Parallel Cellular Automata

NASA Astrophysics Data System (ADS)

He, Mingfeng; Ruan, Hongbo; Yu, Changliang

We presented a predator-prey lattice model containing moveable wolves and sheep, which are characterized by Penna double bit strings. Sexual reproduction and child-care strategies are considered. To implement this model in an efficient way, we build a fully parallel Cellular Automata based on a new definition of the neighborhood. We show the roles played by the initial densities of the populations, the mutation rate and the linear size of the lattice in the evolution of this model.

BEAM CONTROL PROBE

DOEpatents

Chesterman, A.W.

1959-03-17

A probe is described for intercepting a desired portion of a beam of charged particles and for indicating the spatial disposition of the beam. The disclosed probe assembly includes a pair of pivotally mounted vanes moveable into a single plane with adjacent edges joining and a calibrated mechanical arrangement for pivoting the vancs apart. When the probe is disposed in the path of a charged particle beam, the vanes may be adjusted according to the beam current received in each vane to ascertain the dimension of the beam.

Comparison of a Physical and Numerical Mobile-Bed Model of Beach and T-Head Groin Interaction

DTIC Science & Technology

2011-05-01

Hydraulic Centre’s Large Area Basin (LAB), utilizing a set of moveable wave generators capable of providing long-crested waves to match a variety...was conducted manually from a bridge as shown in Figure 4. The location of the transect (Profile 2) is shown in Figure 2. Planform morphology was...4. Physical model oblique view showing profile measurement location and bridge . 2617 The T-head groins and the shore-normal breakwater trunk at the

Performance Evaluation of the microPET®—FOCUS-F120

NASA Astrophysics Data System (ADS)

Laforest, Richard; Longford, Desmond; Siegel, Stefan; Newport, Danny F.; Yap, Jeffrey

2007-02-01

microPETreg-Focus-F120 is the latest model of dedicated small animal PET scanners from CTI-Concorde Microsystems LLC, (Knoxville, TN). This scanner, based on the geometry of the microPET-R4, takes advantage of several detector modifications to the coincidence processing electronics that improve the image resolution, sensitivity, and counting rate performance as compared to the predecessor models. This work evaluates the performance of the Focus-F120 system and shows its improvement over the earlier models. In particular, the spatial resolution is shown to improve from 2.32 to 1.69 mm at 5 mm radial distance and the peak absolute sensitivity increases from 4.1% to 7.1% compared to the microPET-R4. The counting rate capability, expressed in noise equivalent counting rate (NEC-1R), was shown to peak at over 800 kcps at 88 MBq for both systems using a mouse phantom. For this small phantom, the NECR counting rate is limited by the data transmission bandwidth between the scanner and the acquisition console. The rat-like phantom showed peak NEC-1R value at 300 kcps at 140 MBq. Evaluation of image quality and quantitation accuracy was also performed using specially designed phantoms and animal experiments

PET/CT alignment calibration with a non-radioactive phantom and the intrinsic 176Lu radiation of PET detector

NASA Astrophysics Data System (ADS)

Wei, Qingyang; Ma, Tianyu; Wang, Shi; Liu, Yaqiang; Gu, Yu; Dai, Tiantian

2016-11-01

Positron emission tomography/computed tomography (PET/CT) is an important tool for clinical studies and pre-clinical researches which provides both functional and anatomical images. To achieve high quality co-registered PET/CT images, alignment calibration of PET and CT scanner is a critical procedure. The existing methods reported use positron source phantoms imaged both by PET and CT scanner and then derive the transformation matrix from the reconstructed images of the two modalities. In this paper, a novel PET/CT alignment calibration method with a non-radioactive phantom and the intrinsic 176Lu radiation of the PET detector was developed. Firstly, a multi-tungsten-alloy-sphere phantom without positron source was designed and imaged by CT and the PET scanner using intrinsic 176Lu radiation included in LYSO. Secondly, the centroids of the spheres were derived and matched by an automatic program. Lastly, the rotation matrix and the translation vector were calculated by least-square fitting of the centroid data. The proposed method was employed in an animal PET/CT system (InliView-3000) developed in our lab. Experimental results showed that the proposed method achieves high accuracy and is feasible to replace the conventional positron source based methods.