bluuebunny/crossref_metadata_2025 huggingface dataset:
TU‐D‐204C‐03: Machine Learning for Medical Image Processing and Pattern Recognition
Authors: Suzuki K
Published: August 2010

Machine learning plays an essential role in medical image analysis, because objects such as lesions and organs in medical images cannot be modeled accurately by simple equations; thus, tasks in medical image analysis require essentially “learning from examples.” One of the most popular uses of machine learning in medical image analysis is the classification of objects such as lesions into certain categories (e.g., abnormal or normal, lesions or non‐lesions). This class of machine leaning uses features (e.g., diameter, contrast, and circularity) extracted from segmented objects as information for classifying the objects. Machine learning techniques in this class include linear discriminant analysis, a k‐nearest neighbor classifier, an artificial neural network, and a support vector machine.

Recently, as available computational power increased dramatically, a new class of machine learning called pixel/voxel‐based machine learning emerged in medical image processing and analysis, which uses pixel/voxel values in images directly instead of calculated features as input information; thus, feature calculation is not required. Because pixel/voxel‐based machine learning can avoid errors caused by inaccurate segmentation and feature calculation, the performance of the pixel/voxel‐based machine learning can be better than common feature‐based machine learning. Such advanced machine‐learning techniques in this class include neural filters, neural edge enhancers, massive‐training artificial neural networks, convolution neural networks, and shift‐invariant neural networks. This lecture will provide an overview of techniques, methodologies, and applications of machine learning used in medical image processing and pattern recognition, which have been developed and advanced mainly in the field of diagnostic radiology in the past two decades or so. The applications of these machine‐learning techniques include quantum noise reduction, enhancement of the boundary of an organ, lesion enhancement, classification of lesions, and computer‐aided diagnosis. Once we have learned such machine‐learning techniques and methodologies, they can be translated quickly into new techniques for solution of problems in radiation therapy.

Learning Objectives:

1. Understand the basic principle of machine‐learning techniques

2. Learn various techniques in the two major classes of feature‐based and mitationsof machine learning

3. Understand the advantages and limitations of machine‐learning techniques

4. Learn applications of machine‐learning techniques in medical image processing and pattern recognition

5. Consider applications of machine‐learning techniques and methodologies in the field of radiation therapy
TU‐E‐BRB‐08: Rapid Arc Patient Specific Dose Delivery Accuracy under Extreme Mechanical Limits Using Linac Log Files
Authors: Wijesooriya K , Benedict S , Read P , Rich T , Larner J
Published: August 2010

Purpose: To assess the accuracy of RapidArc (RA) delivery for treatment machine operation near allowable mechanical limits in DMLC leaf velocities, gantry speeds, and dose rates. Method and Materials: Thirty RA patient plans were created for treatment of gastrointestinal and head and neck cancers on a Trilogy unit. Three RA plans per patient were generated; one with medium MLC velocities, highest gantry speeds and dose rates (case 1); one with maximal allowable MLC leaf velocities (case 2); and one with lowest gantry speeds (case 3). Combinations of dose rates (140 – 600 Mu /min), gantry speeds (2 – 5.4 deg/s), and DMLC leaf velocities (1.3 – 2.4 cm/s) were utilized to test the RapidArc delivery accuracy. Linac delivery log files were acquired after delivery of each plan. In‐house software was used to read in the original RapidArc DICOM plan and update the plan to reflect the delivered plan taking into account the MLC leaf positions, gantry positions and MU. This DICOM RT plan was imported back to Eclipse and the delivered 3D dose map recomputed. Finally the planned and delivered 3D isodose maps were imported into a 3D gamma analysis algorithm to evaluate the dosimetric differences. Results: For the three cases indicated above MLC leaf position discrepancies are: 0.8 ±0.2, 1.2 ± 0.2, 0.8 ± 0.2 mm; maximum gantry position discrepancies are: 0.9 ±0.2, 0.9 ±0.2, 0.6 ±0.1 deg, and maximum differences in delivered MU per control point are: 0.2±0.1, 0.2 ±0.1, and 0.04±0.01 respectively. The 3D Gamma factor acceptance rates are better than 97%. Conclusion: This work shows that the accuracy of RapidArc delivery holds across the full space of gantry speeds, leaf velocities, and dose rates with small dosimetric uncertainties. A novel technique to obtain the delivered 3D dose distributions using machine log files is also presented.
TU‐E‐204B‐01: First Demonstration of Image‐Based Dynamic MLC Tracking of a Moving Target during Intensity Modulated Arc Therapy
Authors: Poulsen P , Cho B , Sawant A , Ruan D , Højbjerre K , Keall P
Published: August 2010

Purpose:Intensity modulated arc therapy (IMAT) enables efficient and highly conformai dose delivery. However, the dose distribution can be compromised by intrafraction target motion. Dynamic MLC (DMLC) tracking can potentially maintain the planned target dose distribution. The purpose of this study was to use a single kV imager for DMLC tracking during IMAT and to investigate the ability of this tracking to maintain the planned dose distribution. Method and Materials:A motion phantom carrying a 2D ion chamber array and build‐up material with an embedded gold marker was programmed to reproduce eight representative tumor trajectories (four prostate, four lung tumors). For each trajectory, a low and high intensity modulated IMAT plan were delivered with and without DMLC tracking, and the resulting 2D dose distributions were measured. The 3D real‐time target position signal for tracking was provided by fluoroscopic kV images acquired immediately before and during treatment. Each kV image was used together with all previous images to estimate the 3D target position and then the MLC leaves were refitted to this estimated target position. For lung, a prediction algorithm was used to compensate for the tracking latency. A 3%/3mm γ‐test was used to quantify the discrepancy between the measured dose distributions and a reference dose distribution delivered without target motion. Results:For the low modulated plans, tracking reduced the mean 3%/3mm γ‐failure rate from 32% to 0.2% for prostate and from 14% to 1% for lung. For the high modulated plans, the γ‐failure rate reduction was from 17% to 6% (prostate) and from 36% to 11% (lung). The finite MLC adaptation speed was a major cause for the residual γ‐failures during tracking. Conclusion:Image‐based tracking with IMAT was demonstrated for the first time. The tracking greatly improved the dose distributions to moving targets. Conflict of Interest: Supported by NTH/NCI R01‐93626 and Varian Medical Systems.
WE‐A‐204C‐01: Magnetic Resonance Safety and Compatibility Issues at High Magnetic Fields
Authors: Clarke G
Published: August 2010

This review address a number of areas of safety concern in MRI, emphasizing those that gain increased importance for high‐field (≥ 3 Tesla) MRI systems. First, the effects of magnetic fields on the patient will be discussed, including the main, Bo magnetic fields. Topics shall include physiological concerns and regulatory guidelines applicable to the magnitude of the magnetic field strength. Second, the biological effects of radiofrequency (RF) magnetic fields will be addressed, introducing the concepts of eddy currents, specific absorption rate (SAR) and the Food and Drug Administration's (FDA) guidelines that deal with this topic. Finally, physiological consequences of pulsed gradient fields will be covered, including the audible noise generated by the gradient coils, nerve stimulation experienced in gradient‐intense pulse sequences and the FDA's guidelines regarding limitations and control of dB/dt. This presentation will also include a discussion on approaches to managing the MRI system's magnetic fields effects on the environment, including unanticipated flying objects (UFOs), the ACR Zone system for MRI suite plans and a detailed review of patient contraindications for MRI studies. Patient safety issues also include the description of the risks of using gadolinium (Gd)‐based and superparamagnetic iron oxide (SPIO) contrast agents. A brief discussion of the risks to pregnant patients and clinical MRI workers will also be included. Finally, the causes and dangers of superconducting magnet malfunction, focusing on cryogen boil‐off, safety switch design, spontaneous quenches and controlled quenches will be undertaken.

At the end of this presentation the attendee should be able to:

▪ discuss the major biological effects that can be arise from the magnetic fields produced by high‐field MRI systems.

▪ enumerate the safety concerns engendered by the used of exogenous contrast agents in MRI.

▪ explain the safety features that should be incorporated in the design of the MRI suite to reduced adverse events due to UFOs, patient heating and magnet quenches.
WE‐B‐204C‐01: Postron Emission Mammography
Authors: MacDonald L
Published: August 2010

Specialized positron emission tomography (PET) systems dedicated to imaging breast cancer have been proposed and developed since the mid‐1990s. The term positron emission mammography (PEM) has been applied to this specialized area of PET scanners and scanning.

While progress has been made in reversing a long increasing trend of breast cancer deaths in the U.S. and elsewhere, there is still a relatively high incidence of breast cancer diagnosis and mortality: an estimated 192,000 cases, and 40,000 deaths in the U.S. in 2009. This is the second leading cause of cancer deaths in women in the U.S. Screening X‐ray mammography has played an important role in reversing the trend of increasing deaths, and is the primary imaging modality for breast cancer screening. A limitation of screening and diagnostic mammography is its lack of specificity to malignant disease, resulting in many false positives. A number of imaging methods are used to further investigate equivocal mammography findings, including ultrasound, magnetic resonance imaging (MRI), scintigraphy, and PEM.

PET is a functional imaging modality used routinely in oncology to image hyper‐metabolic lesions, including breast cancers. However, the spatial resolution of whole‐body PET (WB‐PET) scanners limits their usefulness in early breast cancer because lesion sizes at diagnosis tend to be smaller than can be reliably imaged with WB‐PET. Dedicated PEM systems focus on improved spatial resolution for imaging early breast cancer, and its functional nature is seen to complement the morphological information provided by mammography. One proposed use of PEM is to improve specificity in diagnosing suspicious but equivocal findings in mammography. PEM has also been suggested for identifying multi‐focal, multi‐centric, or bilateral disease for purposes of planning surgical treatment, for guiding and monitoring therapies, and for better identification of ductal carcinoma in situ.

This lecture will provide a brief history of PEM development, give the current status of PEM, compare PEM to WB‐PET and mammography, and discuss clinical applications and operations.

Learning Objectives:

1. At the end of this lecture, attendees should be able to

2. Understand the differences between whole‐body PET and PEM

3. Understand the differences between mammography and PEM

4. List possible clinical applications/indications for PEM

5. Describe clinical operation and requirements of PEM scanning
WE‐D‐BRB‐02: Characterization of Kilovoltage X‐Ray Spectra Using Measurements with a High‐Purity Germanium Detector and Monte Carlo Simulations
Authors: Moga J , DeWerd L
Published: August 2010

Purpose: Photon spectra of a COMET MXR‐320/26 x‐ray tube were measured and corrected for the detector response calculated using Monte Carlo (MC) simulations. Measured (corrected) spectra were compared to spectra from BEAM/FLURZnrc simulations, SpekCalc, and Gesellschaft für Strahlen‐und Umweltforschung mbH München (GSF) Report 560. Methods and Materials: Several NIST‐traceable x‐ray beams ranging from 20 kVp to 250 kVp were measured with a high‐purity germanium detector. The detector was positioned 4.3 m from the focal spot of the tube along the central axis. Pinhole collimation reduced the fluence rates to measurable levels using a tube current of 1 mA.. The entire measurement apparatus was modeled using the MCNP5 MC code. A detector response function was calculated from the model, and the measured spectra were corrected for detector response. The SpekCalc program [Poludniowski et al, Phys. Med. Biol, 54, N433–N438, 2009] was used to generate spectra. The full model of the x‐ray tube was used to simulate spectra with the BEAMnrc and FLURZnrc MC codes. The measured (corrected), calculated and GSF spectra were compared. Results: The measured (corrected) spectra of this investigation generally compare well with those from the BEAMnrc/FLURZnrc simulations, as well as with those generated with the SpekCalc program and from GSF. Differences in the various spectra, particularly in the abundance of W L‐shell fluorescence for the lower energy beams, are largely due to the physics of the programs or codes being used. Conclusions: X‐ray beam measurements using novel correction methods for bremsstrahlung spectra, as well as simulations of the full x‐ray tube geometry, were presented. This direct comparison benchmarks the MC and analytical methods commonly used for x‐ray beam characterization against physical measurements and reveals some of the subtle differences in the various calculation methods.
TH‐A‐204C‐01: Cone‐Beam CT: Principles Practicalities and Applications
Authors: Siewerdsen J
Published: August 2010

The topic of C‐arm cone‐beam CT (CBCT) including principles of 3D reconstruction image quality radiation dose quality assurance and clinical applications. The availability of such systems has grown over the past several years particularly in light of performance enhancements gained through the incorporation of a flat‐panel detector (FPD) in the imaging chain in place of conventional x‐ray image intensifiers. Such FPD‐based systems demonstrate increased field of view higher 3D spatial resolution improved noise characteristics and the capability to visualize soft‐tissue structures. Applications include neurovascular and cardiovascular image‐guided interventions as well as a growing spectrum of nonvascular and tumor surgeries. The basic principles of cone‐beam CT image reconstruction are reviewed (focusing on prevalent implementations of the Feldkmp algorithm) in comparison to conventional fan‐beam filtered backprojection. The influence of image artifacts most relevant to C‐arm cone‐beam CT are reviewed — in particular x‐ray scatter object truncation and the “cone‐beam” artifact. The factors governing 3D image quality are explained with emphasis on the ability to image soft‐tissue structures and issues of radiation dose characterization and quality assurance are discussed. An ever‐increasing spectrum of C‐arm or C‐arm‐like cone‐beam CT systems is discussed in relation to various applications. Emphasis throughout is in regard to factors most relevant to the practicing medical physicists.

Learning Objectives:

1. Basic principles of 3D cone‐beam CT reconstruction

2. Image quality and artifacts most relevant to cone‐beam CT

3. Essential factors pertinent to C‐arm cone‐beam CT quality assurance

4. Spectrum of systems and applications of C‐arm cone‐beam CT
TH‐C‐BRB‐06: Advanced Dosimetry Techniques for Accurate Dose Measurement of Small and Nonstandard Fields
Authors: Chung E , Soisson E , Bouchard H , Seuntjens J
Published: August 2010

Purpose: To establish reference dosimetry techniques for accurate dose measurement of small and nonstandard fields and application to nonstandard field deliveries. Methods and Materials: A cylindrical PMMA phantom filled with water was constructed in the center of which reference absorbed dose to water was measured. Two candidate plan‐class specific reference (pcsr) fields for (i) linac‐based and (ii) TomoTherapy®‐based typical head and neck IMRT deliveries were created on the CT images of the phantom. The absorbed dose in each pcsr field normalized to that in a 10×10 cm2 was measured using four reference detectors: Gafchromic® EBT films a diamond detector and an in‐house developed guarded liquid ionization chamber (GLIC‐03) for the linac‐based IMRT delivery and a PTW microLion chamber for the TomoTherapy®‐based IMRT delivery. Based on the new dosimetry formalism pcsr correction factors kQpcsr,Qfpcsr,fref were determined for five air‐filled ionization chambers: Exradin A12 NE2571 Exradin A1SL Exradin A14 and PinPoint® 31006. The correction factor measurements were carried out in fully‐rotated and collapsed deliveries for the linac‐based IMRT delivery and only in a fully‐rotated delivery for the TomoTherapy®‐based IMRT delivery. Results: For the linac‐based IMRT delivery the evaluated overall uncertainty in measuring kQpcsr,Qfpcsr,fref was 0.3 %. The kQpcsr,Qfpcsr,fref is chamber independent within uncertainty (0.9955–0.9986) and systematically smaller than unity in the fully‐rotated delivery. In the collapsed delivery the correction factor was more dependent on the chamber type (0.9922–1.0048). For the TomoTherapy®‐based IMRT delivery kQpcsr,Qfpcsr,fref was above unity (1.0037–1.0076) with a 0.3 % measurement uncertainty. However the correction factor was different by 0.33 % between the Farmer‐type chambers and the smaller ionization chambers. Conclusions: The demonstrated dosimetry techniques carried out the relative dose measurements in the pcsr fields to within 0.3 % 1 uncertainty level. These dosimetry techniques will be helpful to improve dosimetric accuracy of other nonstandard field deliveries.
TH‐C‐BRB‐09: Design and Initial Performance of a Large Cross‐Section Multi‐Element Ionization Chamber System for Water Equivalent Range Measurements of Pristine Proton Fields
Authors: Farr J , Mertens T , Bäumer C , Mukherjee B , Marchand B , Stuschke M
Published: August 2010

Purpose: To describe the design and initial testing of a large diameter multilayer ionization chamber (MLIC) system for water equivalent range measurements of pristine proton fields. Method and Materials: The MLIC uses a large 120 mm physical diameter collecting cross‐section in a stacked vented parallel plate geometry of 180 layers spaced 0.8 mm apart. The plates are fabricated from printed circuit board material where copper traces have been etched to form the conductive elements for the ionization chambers. In addition a dedicated software package was developed to assist with device calibration data acquisition and analysis.

Computer modeling of the MLIC was performed with the Monte Carlo (MC) code FLUKA. Radiological testing was performed in a dedicated proton pencil beam scanning (PBS) therapeutic delivery system. The energies tested varied from 100–230 MeV. A series of 10 pristine depth profiles were first acquired for reference within this energy range by longitudinally scanning a discrete parallel plate ionization chamber of 84 mm diameter in a water phantom. After a calibration routine was applied to the MLIC the same energies were tested with the MLIC and the results compared. Additional tests were performed at different fluence rates to evaluate changes in response to detector bias and charge quantum (QC) settings. Results: The analyzed data from the MC simulation and MLIC physical data compared within one mm to the water phantom reference data under the conditions tested. The MLIC results were not sensitive to bias setting but depended with fluence rate on the QC setting. Conclusion: The initial test of the new MLIC prototype provided satisfactory results with regard to water equivalent range accuracy in comparison to reference measurements from the PBS system. Some flexibility is provided with different fluence rates by adjusting the QC. The detailed results will be presented and discussed.
TH‐C‐BRB‐10: Extraction of Perturbation Factors for Parallel‐Plate Chambers in Electron Beams Using a Plastic Scintillation Detector
Authors: Lacroix F , Guillot M , McEwen M , Cojocaru C , Gingras L , Beddar S , Beaulieu L
Published: August 2010

Purpose: To present a method to experimentally extract the overall perturbation factor pQ (the product of pwall and prepl) in megavoltage electron beams for NACP and Roos parallel plate chambers using a perturbation‐free plastic scintillation detector (PSD). Method and Materials: We used a single scanning PSD mounted on a high precision scanning stage to measure depth dose curves in 6 12 and 18 MeV clinical electron beams. We also measured depth doses using NACP and Roos parallel plate chambers. Perturbation factors were extracted by comparing PDDs measured using the Roos and NACP chamber to PDDs measured using the PSD. Monte‐Carlo simulations using EGSnrc were performed to validate that the PSD is a perturbation‐free detector in electron beams. Results: Our experimental results show excellent concordance with the Monte‐Carlo simulation results of various authors on the subject. We show that the perturbation factors for the NACP and Roos chambers increase substantially with depth especially for low energy electron beams. We show that using an effective point of measurement (EPOM) placed inside the air cavity reduces the variation of perturbation factors with depth. The protocol recommendations suggesting to place the point of measurement at the inside face of the front window appear to be incorrect for parallel plate chambers and lead to errors in the R50 of approximately 0.4 mm at 6 MeV 1 mm at 12 MeV and 1.2 mm at 18 MeV. Conclusion: The results indicate that PSDs can be used as perturbation‐free detectors in reference dosimetry and that PSDs can be used to experimentally extract ionization chamber perturbation factors.
TH‐D‐BRB‐01: A Software Solution for Independent Dose Calculation of Helical Tomotherapy
Authors: Dzintars E , Stathakis S , Papanikolaou N
Published: August 2010

Purpose: To translate and write helical tomotherapy treatment information into a non‐helical format such that an independent dose calculation method implementing the EGS4/MCSIM software environment is viable. Method and Materials: In‐house software was developed using the MATLAB computing platform to translate helical tomotherapy treatment sinogram files into a non‐helical format. Several steps are involved in this process. The patient .xml file is obtained through archived information to identify the procedural sinogram and several other delivery parameters. The sinogram is translated to create 51 fluence maps corresponding to the 51 discrete angles over which a complete tomotherapy rotation is divided effectively converting a helical delivery into a 51‐angle delivery. The in‐house software writes an input file referencing these 51 fluence maps that is readable within the Monte Carlo dose calculation user code EGS4/MCSIM. EGS4/MCSIM calculates dose using this translated data providing an independent dose verification method. The final step is to evaluate the EGS4/MCSIM calculations against the treatment planning system. Results: Initial MATLAB programming work has been successful in translating the helical tomotherapy sinogram files. The software is able to decode the sinogram and create the necessary input files for EGS4/MCSIM dose computation. Preliminary sample patients have shown decent agreement with initial percent differences ranging from –6.0% to 3.5% for point doses. Sampled dose profiles have shown mean percent differences within 3% for both horizontal and vertical orientations. Conclusion: This work demonstrates the potential for implementing helical delivery modalities into independent dose calculation software. This work shows that it is possible to decode a helical sinogram use known parameters to create dose maps and with those maps write an input file for EGS4/MCSIM. Ongoing work is being performed to refine the dose verification process in the EGS4/MCSIM environment utilizing input files created through the in‐house software.
Poster — Thur Eve — 30: Plastic Scintillation Detector Characterization for Small Fields and Stereotactic Radiosurgery Quality Assurance
Authors: Gagnon J , Thériault D , Guillot M , Archambaultt L , Beddar S , Gingras L , Beaulieu L
Published: August 2010

Purpose: To compare the performance of a plastic scintillation detector (PSD) for quality assurance (QA) in stereotactic radiosurgery to micro‐chamber (MC), gafchromic films, shielded diode (SD) and unshielded diodes (UD). Method and Materials: The PSD consists of a 1 mm diameter by 1 mm long scintillating fiber coupled to a polymethyl‐methacrylate optical fiber. Output factors and dose profiles for apertures used in radiosurgery have been measured. Moreover, a typical stereotactic radiosurgery treatment, using four non‐coplanar arcs, was delivered on a spherical phantom in which UD, MC or PSD was placed at the isocenter, where 15 Gy was prescribed. Results: The output factors measured with the PSD are within a mean discrepancy of 1 % compared to UD for the small apertures when normalized to the 35 mm cone. For larger cones the PSD is within 1.3% compared to the SD and the MC. When done with a 35 mm cone, the measured dose for an entire typical stereotactic plan by the PSD is within 1.8% of the measurement performed using the MC and within 1% of the planning system. Volume averaging of the MC can be observed for the 5 mm aperture, where the PSD measurement differs by as much as 9.1%. Conclusion: For stereotactic radiosurgery treatment verification, the PSD gives accurate results compared to the MC once the output factor ratio are taken into account to correct for the averaging effect of the MC. The PSD shows great potential for stereotactic radiosurgery QA measurements.
Poster — Thur Eve — 36: Lung SBRT: Dosimetric Evaluation of 4DCT Based Treatment Planning in Presence of Respiratory Motion
Authors: Jiang R , Osei E , Fleck A , Gopaul D , Barnett R
Published: August 2010

The respiratory related dosimetric uncertainties in the 4DCT based lung stereotactic body radiotherapy (SBRT) treatment planning and treatment delivery are evaluated by performing density assignment correction (DAC) in the ITV. Siemens 40‐slice CT scanner was used to acquire 8 phases of 4DCT images and a free breathing CT scan using a CIRS Dynamic Thorax Phantom. The ITV was created from 4DCT scan and treatment planning was done in free breathing CT scan. The ITV dose coverage was measured by CIRS phantom with ionization chamber moving together with the tumor during the beam delivery under free breathing treatment, which considers the time and positional averaged distribution of tissue heterogeneities within the ITV. The measured results are compared with the treatment planning with and without DAC in the ITV. The ITV dose coverage from the measurement is 1.9% higher than the planned ITV mean dose. The ITV received adequate dose due to the presence of effective density of the tumor within the ITV when the treatment is delivered under free breathing. The plan accounting for respiratory motion by assigning an average tumor density into the treatment planning had better uniform dose than the plan without DAC. By incorporating the ITV tumor density override into treatment planning dose calculation, the ITV dose coverage becomes more uniform and the mean dose of ITV increases and more closely matches the measured values than the plan without DAC in the ITV.
Poster — Thur Eve — 40: Evaluation of Respiratory‐Induced Motion
Authors: St‐Pierre C , Tremblay D , Beaulieu L , Archambault L
Published: August 2010

Purpose: Collect statistics on respiratory induces internal motion to improve population based margin definition of target volumes and organs at risks and to determine the feasibility of screening patients that would most benefits from a 4DCT exam. Methods: Motion of relevant internal and external region of interest was evaluated on 4DCT datasets of 16 patients in an open study. Patients were selected based on tumour location. For a given 4DCT dataset, motion was characterized for each of 10 phases of the breathing cycle. Trace differences between two methods of respiratory signal acquisition were also evaluated. Results: Motion in the superior‐inferior (SI) direction, unlike other directions, showed a uniform motion trend between different structures. External markers have an opposed phase motion compared to internal structures. Diaphragm usually showed the largest averaged magnitude of motion (1.55±0.50 cm) with a wide range of amplitude. As can be expected, gastro‐intestinal tumors (0.88±0.27 cm) are in average less mobile than lung tumors (1.18±0.90 cm). Respiratory signal acquisition systems used for this study produced very similar traces regarding baseline variation and peak shape. Conclusion: Population‐based specific organs motion will be used for personalized treatment planning (e.g. delineation of margins, contours). Most structures have a similar shaped motion (i.e. no phase mismatch) and amplitude in the SI direction, except for external markers. Abdomen AP motion is a promising external indicator of internal motion magnitude.
Poster — Thur Eve — 51: An Investigation of Geometry Issues for EPID Dosimetry during Rotational IMRT
Authors: McCowan PM , McCurdy BM , Greer PB , Rickey DW , Rowshanfarzad P
Published: August 2010

INTRODUCTION: Amorphous‐silicon electronic portal imaging devices (EPIDs) have been established as useful tools for dosimetry. To accurately reconstruct the patient dose delivered during rotational IMRT, one must acquire time‐resolved EPID images as a function of gantry‐angle. Dose reconstruction accuracy is directly impacted by the accuracy of the geometry of the imaging system, including the gantry‐angle readout (i.e. source geometry) and the EPID support‐arm sag (i.e. imager geometry). This work investigates these two factors. METHODS: The EPID support‐arm sag was investigated through measurements performed on Varian E‐arm and R‐arm models at two institutes and employing two different analysis methods. One method imaged an isocentric ball‐bearing whose position was tracked over all gantry‐angles. The second method involved analysing field edges to obtain the field centre location of all images. Gantry‐angle accuracy was examined by comparing the gantry‐angle indicated at the treatment console readout to the gantry‐angle written to the EPID DICOM header. We developed a method of measuring gantry‐angle directly from the gantry‐angle potentiometer. RESULTS: The E‐arm showed maximum displacement of roughly 0.6mm (cross‐plane) and 0.8mm (in‐plane). R‐arm results were significantly worse, estimated at 8.5mm (cross‐plane) and 5.0mm (in‐plane). Gantry‐angle analysis demonstrated approximately 2 degrees of uncertainty in the gantry‐angle contained in the EPID image. A direct measurement of the gantry angle potentiometer was demonstrated. CONCLUSIONS: Two main factors affecting patient dose reconstruction using EPID dosimetry have been investigated. EPID support‐arm sag can be measured (and corrected). Near real‐time gantry‐angle measurement can be performed through directly monitoring the potentiometer signal.
Poster — Thur Eve — 53: Reproducibility of TI‐201 for Cardiac Micro SPECT Imaging with a Rat Model
Authors: Nahin MF , Lockwood J , Strydhorst J , Kordos M , Ruddyence TD , Wells RG
Published: August 2010

Serial imaging with micro SPECT/CT is an important 3D in vivo technique used to study heart disease in small‐animal models and develop new therapies and new radiotracers. Measurement of myocardial perfusion uniformity (PH), ejection fraction (EF), end systolic volume (ESV) and, end diastolic volume (EDV) in rat model are important indices of heart function that can be derived from SPECT images. Knowledge of the uncertainty of these measurements is critical to discerning true changes and to determining sample sizes. The aim of this study is to produces the inter‐ and intra‐ subject reproducibility of left ventricular volumes, ejection fraction and perfusion homogeneity with Tl‐201, a common cardiac perfusion tracer, in a rat model using micro SPECT/CT. The scanner has four heads with nine pinholes each (total 36 pinholes). Three healthy rats were injected with 0.5mCi of Tl‐201 and scanned weekly for five weeks. Each scan lasted 30 min and began 30 min post‐injection. The images were reconstructed and processed with a clinical software package (4DM‐SPECT) to get the heart functions (EDV, ESV, EF and PH). EDV and ESV were corrected for changes in rat weight. The standard deviation in the measured values (across scans) was 5.88% for EDV and 6.90% for ESV, 3.2% for EF, and 6% for PH. The reproducibility between rats was similar.
Poster — Thur Eve — 55: GRRCC‐Monte Carlo Treatment Planning Research Environment (MCTPRE)
Authors: Osei EK , Willick K , Puzzuoli D , Wernik C , Zhan L , Barnett R
Published: August 2010

The implementation of Monte Carlo dose calculation algorithms in clinical radiotherapy treatment planning systems has been anticipated for many years however, its introduction into routine clinical practice has been delayed by the extent of calculation time required. With the advent of faster computers, Monte Carlo (MC) algorithms will become a standard calculation algorithm in clinical treatment planning systems. The purpose of this work was to develop a Monte Carlo based radiotherapy treatment planning research environment (MCTPRE) that uses patient‐specific computed tomography (CT) dataset. We have developed a windows based graphical user interface (GUI) that makes it very easy to import patient specific plans from a treatment planning system in either DICOM or RTOG format to a MC treatment planning research environment and can also be used to simulate simple patient specific treatment plans. The MCTPRE uses the BEAMnrcMP Monte Carlo code, which is based on the underlying ESGnrcMP particle transport code to simulate the Varian Clinac 21EX accelerator treatment head for 6 and 15MV photons and 6–20 MeV electron beams. The DOSXYZnrc Monte Carlo code is use for patient specific phantom dose calculations. We compared dose distributions from calculations done with a TPS and with the Monte Carlo code. The GUI incorporating the Monte Carlo code is a very useful research tool for benchmarking treatment planning systems (TPS), testing technique development, and dose verification. Future development will include a direct interface to a TPS.
Simple Model for Testing Drugs against Nonreplicating
Mycobacterium tuberculosis
Authors: Sala Claudia , Dhar Neeraj , Hartkoorn Ruben C. , Zhang Ming , Ha Young Hwan , Schneider Patricia , Cole Stewart T.
Published: August 2010

Nonreplicating or dormant cells of
Mycobacterium tuberculosis
constitute a challenge to tuberculosis (TB) therapy because of their tolerance or phenotypic resistance to most drugs. Here, we propose a simple model for testing drugs against nongrowing cells that exploits the 18b strain of
M. tuberculosis
, a streptomycin (STR)-dependent mutant. Optimal conditions were established that allowed 18b cells to replicate in the presence of STR and to survive, but not multiply, following withdrawal of STR. In the presence of the antibiotic,
M. tuberculosis
18b was susceptible to the currently approved TB drugs, isoniazid (INH) and rifampin (RIF), and to the experimental drugs TMC207, PA-824, meropenem (MER), benzothiazinone (BTZ), and moxifloxacin (MOXI). After STR depletion, the strain displayed greatly reduced susceptibility to the cell wall inhibitors INH and BTZ but showed increased susceptibility to RIF and PA-824, while MOXI and MER appeared equipotent under both conditions. The same potency ranking was found against nonreplicating
M. tuberculosis
18b after
in vivo
treatment of chronically infected mice with five of these drugs. Despite the growth arrest, strain 18b retains significant metabolic activity
in vitro
, remaining positive in the resazurin reduction assay. Upon adaption to a 96-well format, this assay was shown to be suitable for high-throughput screening with strain 18b to find new inhibitors of dormant
M. tuberculosis
.
Three
Yersinia pestis
Adhesins Facilitate Yop Delivery to Eukaryotic Cells and Contribute to Plague Virulence
Authors: Felek Suleyman , Tsang Tiffany M. , Krukonis Eric S.
Published: August 2010

To establish a successful infection,
Yersinia pestis
requires the delivery of cytotoxic Yops to host cells. Yops inhibit phagocytosis, block cytokine responses, and induce apoptosis of macrophages. The
Y. pestis
adhesin Ail facilitates Yop translocation and is required for full virulence in mice. To determine the contributions of other adhesins to Yop delivery, we deleted five known adhesins of
Y. pestis
. In addition to Ail, plasminogen activator (Pla) and pH 6 antigen (Psa) could mediate Yop translocation to host cells. The contribution of each adhesin to binding and Yop delivery was dependent upon the growth conditions. When cells were pregrown at 28°C and pH 7, the order of importance for adhesins in cell binding and cytotoxicity was Ail > Pla > Psa.
Y. pestis
grown at 37°C and pH 7 had equal contributions from Ail and Pla but an undetectable role for Psa. At 37°C and pH 6, both Ail and Psa contributed to binding and Yop delivery, while Pla contributed minimally. Pla-mediated Yop translocation was independent of protease activity. Of the three single mutants, the Δ
ail
mutant was the most defective in mouse virulence. The expression level of
ail
was also the highest of the three adhesins in infected mouse tissues. Compared to an
ail
mutant, additional deletion of
psaA
(encoding Psa) led to a 130,000-fold increase in the 50% lethal dose for mice relative to that of the KIM5 parental strain. Our results indicate that in addition to Ail, Pla and Psa can serve as environmentally specific adhesins to facilitate Yop secretion, a critical virulence function of
Y. pestis
.
Mucosal Immunization withVibrio choleraeOuter Membrane Vesicles Provides Maternal Protection Mediated by Antilipopolysaccharide Antibodies That Inhibit Bacterial Motility
Authors: Bishop Anne L. , Schild Stefan , Patimalla Bharathi , Klein Brian , Camilli Andrew
Published: August 2010

Vibrio choleraeis the causative agent of cholera, a severe diarrheal disease that remains endemic in many parts of the world and can cause outbreaks wherever sanitation and clean water systems break down. Prevention of disease could be achieved through improved sanitation and clean water provision supported by vaccination.V. choleraeserogroup O1 is the major cause of cholera; O1 serotypes Inaba and Ogawa have similar disease burdens, while O139 is the only non-O1 serogroup to cause epidemics. We showed previously that immunization of adult female mice with purifiedV. choleraeouter membrane vesicles (OMVs) elicits an antibody response that protect neonates from oralV. choleraechallenge and that suckling from an immunized dam accounts for the majority of protection fromV. choleraecolonization. Here we report that lipopolysaccharide (LPS) is the major OMV protective antigen. Mucosal immunization with OMVs from Inaba or Ogawa provides significant cross-serotype protection fromV. choleraecolonization, although serotype-specific antigens are dominant. OMVs from O1 or O139 do not provide cross-serogroup protection, but by immunization with a mixture of O1 and O139 OMVs, cross-serogroup protection was achieved. Neonatal protection is not associated with significant bacterial death but may involve inhibition of motility, as antibodies from OMV-immunized mice inhibitV. choleraemotilityin vitro, with trends that parallelin vivoprotection. Motility assays also reveal that a higher antibody titer is required to immobilize O139 compared to O1, a phenotype that is O139 capsule dependent.
Impaired Immune Tolerance toPorphyromonas gingivalisLipopolysaccharide Promotes Neutrophil Migration and Decreased Apoptosis
Authors: Zaric Svetislav , Shelburne Charles , Darveau Richard , Quinn Derek J. , Weldon Sinéad , Taggart Clifford C. , Coulter Wilson A.
Published: August 2010

Periodontitis, a chronic inflammatory disease of the tissues supporting the teeth, is characterized by an exaggerated host immune and inflammatory response to periopathogenic bacteria. Toll-like receptor activation, cytokine network induction, and accumulation of neutrophils at the site of inflammation are important in the host defense against infection. At the same time, induction of immune tolerance and the clearance of neutrophils from the site of infection are essential in the control of the immune response, resolution of inflammation, and prevention of tissue destruction. Using a human monocytic cell line, we demonstrate thatPorphyromonas gingivalislipopolysaccharide (LPS), which is a major etiological factor in periodontal disease, induces only partial immune tolerance, with continued high production of interleukin-8 (IL-8) but diminished secretion of tumor necrosis factor alpha (TNF-α) after repeated challenge. This cytokine response has functional consequences for other immune cells involved in the response to infection. Primary human neutrophils incubated withP. gingivalisLPS-treated naïve monocyte supernatant displayed a high migration index and increased apoptosis. In contrast, neutrophils treated withP. gingivalisLPS-tolerized monocyte supernatant showed a high migration index but significantly decreased apoptosis. Overall, these findings suggest that induction of an imbalanced immune tolerance in monocytes byP. gingivalisLPS, which favors continued secretion of IL-8 but decreased TNF-α production, may be associated with enhanced migration of neutrophils to the site of infection but also with decreased apoptosis and may play a role in the chronic inflammatory state seen in periodontal disease.
Pathogenic Role of Macrophages in Intradermal Infection of Methicillin-Resistant
Staphylococcus aureus
in Thermally Injured Mice
Authors: Asai Akira , Tsuda Yasuhiro , Kobayashi Makiko , Hanafusa Toshiaki , Herndon David N. , Suzuki Fujio
Published: August 2010

Intradermal infection of methicillin-resistant
Staphylococcus aureus
(MRSA) in burned mice was pathogenically analyzed. An abscess was formed in normal mice intradermally infected with 10
8
CFU/mouse of MRSA, and all of these mice survived after the infection; however, abscess formation was not demonstrated to occur in burned mice similarly exposed to the pathogen, and all of these mice died within 5 days of infection. In burned mice, MRSA infected at the burn site intradermal tissues spread quickly throughout the whole body, while in normal mice, the pathogen remained localized at the infection site. Macrophages (Mφ) isolated from the infection site tissues of normal mice produced interleukin-12 (IL-12) but not IL-10 and were characterized as M1Mφ. These M1Mφ were not isolated from the infection site tissues of burned mice. When normal-mouse infection site tissue Mφ were adoptively transferred to burned mice at the MRSA infection site, an abscess formed, and the infection did not develop into sepsis. In contrast, an abscess did not form and sepsis developed in normal mice that were inoculated with burned-mouse infection site tissue Mφ. These Mφ produced IL-10 but not IL-12 and were characterized as M2Mφ. These results indicate that abscess formation is a major mechanism of host resistance against intradermal MRSA infection. M1Mφ in the tissues surrounding the infection site play a pivotal role in abscess formation; however, the abscess is not formed in burned mice where M2Mφ predominate. M2Mφ have been described as inhibitor cells for Mφ conversion from resident Mφ to M1Mφ.
THE DESIGN OF COMPLEX WAVELET PACKET TRANSFORMS BASED ON PERFECT TRANSLATION INVARIANCE THEOREMS
Authors: TODA HIROSHI , ZHANG ZHONG , IMAMURA TAKASHI
Published: August 2010

The useful theorems for achieving perfect translation invariance have already been proved, and based on these theorems, dual-tree complex discrete wavelet transforms with perfect translation invariance have been proposed. However, due to the complication of frequency divisions with wavelet packets, it is difficult to design complex wavelet packet transforms with perfect translation invariance. In this paper, based on the aforementioned theorems, novel complex wavelet packet transforms are designed to achieve perfect translation invariance. These complex wavelet packet transforms are based on the Meyer wavelet, which has the important characteristic of possessing a wide range of shapes. In this paper, two types of complex wavelet packet transforms are designed with the optimized Meyer wavelet. One of them is based on a single Meyer wavelet and the other is based on a number of different shapes of the Meyer wavelets to create good localization of wavelet packets.
MULTIWAVELET ANALYSIS OF THE SOLUTION FOR PHYSICAL EQUATIONS
Authors: SEKINO HIDEO , II TAKAHIRO , KATO TETSUYA , HAMADA SHINJI , OKAMOTO TAKUMI
Published: August 2010

The solutions of convection and diffusion equations are analyzed using Multiresolution Multiwavelet (MRMW) basis functions of multidimension including time. The distribution representing the solution reconstructed in non-standard form of the higher order MRMW reproduces the original solution in the multidimensional space much more efficiently than the lower order one. Smooth movement of the distribution is observed except for the initial area even using the MRMW of zeroth order but the shape of the distribution is not well reproduced for the case. The initial area is better reproduced by the MRMW of higher order and the wavelet component decays much quicker both in low and high levels of resolution.
DIRECTIONAL SELECTION OF TWO-DIMENSIONAL COMPLEX DISCRETE WAVELET TRANSFORM AND ITS APPLICATION TO IMAGE PROCESSING
Authors: ZHANG ZHONG , KOMAZAKI NARIYA , IMAMURA TAKASHI , MIYAKE TETSUO , TODA HIROSHI
Published: August 2010

In this study, a novel direction selection method using the two-dimensional complex discrete wavelet transform (2D-CDWT) is proposed. In order to achieve arbitrary direction selection, the directional filters are first designed. Calculation procedure of directional selection can be shown as follows: (1) The 16 sub-images are generally generated from the original image by the 2D-CDWT without a down-sampling process and the 12 sub-images that correspond to the high-frequency components are selected. (2) The 12 sub-images are filtered by using the designed directional filter. (3) The down-sampling process is carried out and the resulting images are obtained. Furthermore, this method is applied to the surface analysis of a wafer, and it is confirmed that our method is effective in detecting irregular direction components.
PROCESS MECHANISMS OF INSTITUTIONAL ENTREPRENEURSHIP
Authors: DROEGE SCOTT B. , MARVEL MATTHEW R.
Published: August 2010

Field and historical data from China delineate two specific process mechanisms that facilitate institutional change: diminished utility of regulatory controls and negotiated boundaries of institutional space. These mechanisms tend to have entrepreneurial origins and, together, create new institutions when in the context of other factors that may be present in emerging economy institutional transition. These mechanisms link praxis, or experiential participation, with institutional change, thus enhancing our understanding of the drivers of entrepreneur-initiated institutional transition. Specifically, the effectiveness of regulatory controls decreases in the presence of collective entrepreneurial action and mobilization. In addition, negotiated boundaries of institutional space increase in the presence of reflective shifts in consciousness and increased activity of potential institutional entrepreneurship.