bluuebunny/crossref_metadata_2025_split huggingface dataset:
WE‐G‐220‐07: Treatment Assessment for Pulsed Focused Ultrasound Therapy of Prostate Tumor Using a Clinical 1.5T MRI
Authors: Chen X , Cvetkovic D , Chen L , Ma C 
Published: November 2011

Purpose: Recent in vivo experiments have showed non‐thermal effects of pulsed focused ultrasound (pFUS) on tumor growth delay. This study investigates the application of a clinical 1.5T MR scanner for treatment assessment of prostate tumors after pFUS treatment, which provides a non‐ invasive and accurate way to measure tumor volume for treatment efficacy evaluation, and also an alternative way for small animal tumor model study that generally requires high‐magnetic‐field MRI facility (e.g., the Bruker NMR system). Methods: A mouse tumor model was developed by implanting LNCaP tumor cells in nude mice prostates. When tumor volume reached ∼130 mm3 on MRI, mice were randomly assigned into two groups (n=8): (1) pFUS treatment; (2) control. MRI‐guided pFUS treatment was performed using InSightec ExAblate 2000 with a 1.5T GE MR scanner. Non‐thermal pFUS was delivered for 60 sec per sonication (1MHz; 25W acoustic power; 10% duty cycle, on/off=0.1/0.9 sec). The body temperature was kept <42°C as measured in real‐time by MR thermometry. A total of 4– 8 sonications were used to cover the whole tumor target for each animal. Weekly MR scans were performed using 1.5T scanner to monitor the tumor growth. A ring‐shape surface coil (3 inches) was used for MR signal detection. T2‐weighted MR imaging used fast‐recovery fast‐spin‐echo (FRFSE) sequence with parameters: TR/TE=2200/85ms, NEX=3, matrix=288×288, FOV=7×7 cm2 (resolution=0. 137×0.137mm2), slice thickness=2/1 mm (coronal/axial). Results: Tumor growth delay was quantified using the clinical 1.5T MR scanner after pFUS treatment while normal tumor growth was clearly observed in the control group. A >40% reduction in tumor volume was shown in mice treated with pFUS compared to that for the control mice Conclusion: Clinical 1.5T MRI is able to assess the tumor volume change after pFUS treatment for a small animal model (tumor size: 3–10mm). It may provide an alternative way for treatment assessment for small animal studies.This work is supported by Focused Ultrasound Surgery Foundation, Varian Medical Systems, DOD PC073127 and DOD BC102806.
TH‐A(SAM)‐BRC‐01: Physics and Dosimetry of SBRT
Authors: Miften M , Kavanagh B , Agazaryan N 
Published: November 2011

SBRT is a novel cancer treatment strategy where ultra‐high doses per fraction are used, generally in the range of 6 to 20 Gy per fraction, in a hypofractionated regimen of 5 or fewer fractions. Such high doses per treatment were inconceivable in the past because of concerns about radiation‐induced injury to normal tissue if large volumes of OARs were irradiated to high doses. However, with recent technical advancements in highly‐conformal treatment planning, image‐guided radiotherapy, and delivery technologies, it has become possible to deliver safely very large fractional doses of radiation to lesions in the lung, liver, spine, and prostate. Since SBRT involves technically sophisticated patient repositioning and treatment delivery procedure, it is not uncommon for a treatment to last 40 minutes. Clinicians are usually concerned of a possible compromise in treatment efficacy for individual fractions that require long treatment time because of tumor intra‐fraction motion and patient involuntary movement during radiation delivery, as well as a theoretical risk of intra‐fractional radiation damage repair within tumor cells in the context of prolonged fractional delivery time. In this session, methods for effective, optimal and accurate planning, and efficiency and robustness in the delivery of SBRT, including QA, will be presented so that these concerns are minimized. Furthermore, the technical challenges associated with the clinical implementation of SBRT will be discussed, thereby allowing the wide application of SBRT using current treatment planning and delivery technologies (fixed‐field 3DCRT/IMRT, dynamic arcs, rotational IMRT).The specific objectives of the session are to:1. Describe secure and comfortable immobilization techniques to minimize patient movement, techniques accounting for internal organ motion, and accurate patient repositioning methods using online imaging2. Discuss treatment planning methods to ensure coverage of tumor volume within high dose regions with very rapid fall‐off to surrounding OARs, including the use of Monte Carlo algorithms3. Describe quality assurance and verification techniques for fixed‐field (3DCRT, IMRT) and rotational (static/dynamic arcs, VMAT/Rapid Arc/Tomo) delivery, usually characterized by many small beam segments, and the assessment of target conformity coverage, and high dose “spillage” region
TH‐A‐224‐02: Atlas‐Based Auto‐Segmentation of CT Images for Radiotherapy Planning
Authors: Han X 
Published: November 2011

Treatment planning for high precision radiotherapy of cancer patients requires accurate delineation of both target volumes and critical structures from the planning CT image. Manual contouring is tedious and suffers from large inter‐ and intra‐rater variability. Tools for automated segmentation are thus needed.Atlas‐based approaches have become popular for automatic medical image segmentation due to its general applicability and advancements in deformable image registration techniques. In this talk, we present our research on developing fully automated, atlas‐based methods for segmenting organs at risk from CT images in radiotherapy planning.One particular atlas registration approach that we developed employs a hierarchical scheme and makes use of object shape information in the atlas to improve the registration efficiency and robustness while still being able to account for large inter‐subject shape differences. Together with a multi‐atlas fusion strategy, accurate segmentation results can be obtained for images of different anatomical sites. To make multi‐atlas segmentation computationally feasible, we also take advantage of recent advancements in GPU technology and have implemented our method on NVIDIA GPU cards. The GPU acceleration allows the auto‐segmentation of a typical CT image with 10 atlases to be computed within a time‐frame of several minutes.After presenting validation results, we conclude the talk with discussions about future research directions.Learning Objectives:1. Understand the basic principle and workflow of atlas‐based image segmentation2. Understand how atlas‐based image segmentation technology can help improve consistency and efficiency in structure contouring for treatment planning3. Understand the promises and limitations of existing technology, as well as future research directions
TH‐A‐BRA‐01: Review of the Radiobiological Principles of Radiotherapy
Authors: Orton C 
Published: November 2011

Mechanisms by which radiation kills cells and ways cell damage can be repaired will be reviewed. The effect of radiobiological parameters which we can control for radiotherapy will be discussed including dose/fraction, number of fractions, time between fractions, overall treatment time, and the LET of the radiation. Reasons why we fractionate the way we do will be discussed, along with how sparing of normal tissues using conformal techniques might affect optimal fractionation. The importance of time between fractions will be presented, especially if cancer cells which exhibit hyper‐radiosensitivity are present. The linear‐quadratic model for cell survival for high and low dose rate treatments and the effect of repopulation will be presented and discussed. The effect of LET will be presented as far as the RBE is concerned for both high and low doses.Learning Objectives:1. To understand the importance for radiation therapy of dose/fraction, number of fractions, time between fractions, dose rate, overall treatment time, and the LET of the radiation.2. To understand how geometrical sparing of normal tissues might affect optimal fractionation.3. To understand the linear‐quadratic model for radiotherapy.
TH‐A‐220‐09: A Study of Prostate Edema Resolution Pattern by Principle Component Analysis
Authors: Jiang Y , Zhai Y , Papademetris X , Roberts K , Pathare P , Nath R , Chen Z 
Published: November 2011

Purpose: To investigate and characterize the spatial resolution patterns of prostate edema in permanent prostate brachytherapy for accurate post‐implant dosimetry. Methods: Three patients with prostate cancer received 103Pd seed implant (day‐0) and consented to participate in an IRB approved post‐implant serial CT imaging study. Patient 1 was scanned on days: −1,1, 7, 10, 17, 30, 42; Patient 2: −1, 0, 1, 7, 16, 40; and patient 3: −1, 0, 1, 6, 11, 15, 30, 42. The image of patient 1 on day‐0 was contoured by a radiation oncologist and set as the template image for registration using a validated deformable image registration algorithm. For all voxel points inside the prostate in the template image, their corresponding coordinates in the subsequent images were obtained by the resulting deformation fields. These point sets were further aligned by rigid shape registration so as to reflect the intrinsic edema resolution. Principle component analysis (PCA) was used to compute the variation pattern among the point sets of each patient, and also among the point sets averaged from all patients on days −1, 1, 6/7, 15/16/17, and 40/42. Results: The percentages of the greatest four components of variation over the total variation are 92.0%, 2.9%, 2.1%, 1.2% for patient 1, 43.8%, 32.0%, 10.4%, 8.2% for patient 2, 45.6%, 15.1%, 12.3%, 10.5% for patient 3, and 63.0%, 18.4%, 11.3%, 7.2% for the averaged one. The greatest four components of variation plotted on the surfaces of prostate and of a sphere of similar size provided an easy visualization of major edema resolution patterns. Conclusions: Strong anisotropic edema resolution patterns were observed in patients receiving permanent prostate brachytherapy. PCA analysis and visual inspections indicated that different patients have significantly different edema resolution patterns. It suggests that spatial anisotropy of edema resolution should be considered for accurate dosimetry.This research project is currently funded by the NIH grant R01CA134627‐01
TH‐B‐224‐02: PET Image Segmentation for Radiation Therapy
Authors: Kirov A 
Published: November 2011

Positron emission tomography (PET) brings to radiation therapy of cancer the critical advantage of defining the tumor based on its molecular properties. However, delineating the gross tumor volume (GTV) with PET is problematic due to the uncertainties in the biological and physiological processes governing the tracer uptake and to the instrumental inaccuracy of the PET images. Despite this, the delineation of tumors in PET images is used in radiation therapy for target definition, dose painting and treatment outcome assessment.The lecture will provide examples of the different tumor segmentation tasks and point to the different requirements they may present. It will further point to the segmentation challenges arising from the PET image specifics, inaccuracies and uncertainties. It will also propose a classification of the auto‐segmentation methods used in PET and provide examples of few auto‐segmentation methods representative of the different classes. Finally, the need of evaluation and validation of the segmentation techniques will be discussed.Learning objectives:1. Understand the different requirements to PET segmentation set by the specific goal.2. Be aware of the physical properties of PET images which affect segmentation accuracy.3. Be able to provide a simple classification of the auto‐segmentation tools and explain the need for validation.
TH‐B‐301‐01: FFDM Quality Control Testing in Canada ‐ a Vendor‐Neutral Approach
Authors: Rajapakshe R 
Published: November 2011

Lack of national and international standards for quality control for digital mammography dictates that users have to follow manufacturerˈs recommendations. This leads to significant additional work for facilities with digital mammography systems from multiple vendors. Therefore, a comprehensive and unified quality control test for medical physicists and mammography technologists was developed for the Screening Mammography Program of British Columbia (SMPBC), in collaboration with Ontario Breast Screening Program with the intent of using them as a national standard in Canada.The quality control tests developed for the ACRIN DMIST study were used as the starting point for the new tests; however, due to the recent implementation of AEC algorithms by some manufacturers, it has become difficult to use the uniform phantom suggested by DMIST work. To address this, a simple 19 cm diameter semicircle uniform phantom was designed. Furthermore, it was found that the technologist weekly image quality test should be performed on “FOR PRESENTATION” images so that changes in image processing algorithms (similar to changes in film processing conditions) can be identified. IHE Mammography Integration Profile compliance was also included as part of the Medical Physicists tests.The new unified quality control procedures have been adopted as the standard in the province of BC for more than two years. This unified approach has made it possible to streamline and manage the quality control of screening mammography facilities within the province. The technologist weekly image quality test done with “FOR PRESENTATION” images instead of “FOR PROCESSING” images (as suggested by ACRIN DMIST study findings) have uncovered changes in image processing algorithms that were implemented by manufacturers without the knowledge of the users. The new semicircle uniform phantom is found to be suitable for testing the AEC performance of every digital mammography unit used in the province of BC.Due to the success in the use of the new unified QC tests in the province of BC, we are in the process of promoting this as a national standard for digital mammography quality control in Canada.This presentation will provide an overview of the development and implementation of these vendor neutral unified quality control procedures and its advantages.Learning Objectives:1. Understand the type of testing required for Digital mammography systems.2. Understand the advantages of a unified QA procedure.3. Understand some of the technical and logistical issues involved in implementing vendor neutral QA procedures.4. Understand the importance of using IHE Mammography Integration Profile as part of the Medical Physicist testing.
TH‐C‐224‐01: Reimbursement: Resources and Updates
Authors: Goodwin J 
Published: November 2011

Healthcare reimbursement is a complex, changing environment with multiple payers and multiple sets of rules. The practicing medical physicist should be familiar with reimbursement and coding so that he/she can: 1) assure that fair reimbursement is received for the physics work performed, 2) assure that physics billing is done correctly and in compliance with applicable rules and procedures, and 3) justify the physics staffing levels necessary in the clinic. This presentation will build upon previous general reviews of the mechanisms of Medicare reimbursement and will cover practical aspects for the practicing physicist including where to find information on reimbursement and coding. The National Correct Coding Initiative (NCCI) and Medically Unlikely Edits (MUE) and their effect on daily billing will be reviewed. In addition, proposed changes in the Hospital Outpatient Prospective Payment System (HOPPS) and Medicare Physician Fee Schedule (MPFS) for calendar year 2012 will be discussed.Learning Objectives:1. Become familiar with available resources for reimbursement and coding2. Understand the National Correct Coding Initiative and Medically Unlikely Edits3. Be aware of proposed changes in Medicare reimbursement for 2012
TH‐C‐110‐04: Dual Energy CT Imaging for Density Measurements
Authors: Pelc N 
Published: November 2011

Purpose: Diagnostic CT scanners use polychromatic x‐ray beams, which introduces errors from beam hardening. If the object is composed of a single material corrections for beam hardening can be exact but if the object is heterogenous some errors would remain. Dual energy CT can avoid these errors and can also provide atomic number information.Methods: If transmission measurements at two or more energies are obtained, even with polychromatic beams, more specific information about the object can be obtained. In the diagnostic energy range and if there are no materials with k‐edges in the spectrum, the x‐ray attenuation can be described by a linear combination of two processes (photoelectric absorption and Compton scattering) or, equivalently, two basis materials. The process of calculating the amount of the two basis functions implicitly corrects for beam hardening and therefore can lead to improvements in quantitative accuracy. Implementations of dual energy include dual‐source, rapidly switching kVp sources, dual layer detectors and energy discriminating detectors.Results: Dual energy CT can correct for beam hardening. It can quantify effective atomic number and electron density in each voxel. It can also quantify the amounts of specific materials even in heterogenous voxels. The precision of the dual energy information is limited by statistics and the accuracy can be compromised by scatter.Conclusion: Dual energy CT can provide additional information for quantitative measurements with CT but its limitations need to be appreciated as well.Research sponsored by GE Healthcare.The learning objectives are to familiarize the audience with1. basic principles of dual energy CT2. implementations of dual energy CT3. basis material decomposition4. dual energy CT can characterize materials and correct for nonlinearity (e.g., beam hardening)5. limitations of dual energy CT
TH‐C‐211‐01: International Perspectives on Radiation Protection
Authors: Rehani M , Suleiman O , Rajapakshe R 
Published: November 2011

There are some actions which require international cooperation. An example of good cooperation can be found in the largely seamless international use of credit cards and ATM machines. Conversely, an example where international cooperation has not been effective can be found in the diversity of electricity plugs and sockets in different countries. In the area of radiation protection, there are also examples of good and bad cooperation. The global acceptance of concepts and principles of radiation protection as developed by the International Commission on Radiological Protection (ICRP) such as justification, optimization and dose limitation is a good example. Conversely, there are quite a few examples of non‐agreement or partial agreement of issues in the field of radiation protection, such as dose limits for workers and members of the public, and acceptance of SI units e.g. Sv and Gy against rem and rad. When it comes to radiation protection of patients, there is Universityersal agreement that there should be no dose limits and that the concept of diagnostic reference levels (DRLs) should be used with flexibility. International actions are needed not only to create harmonization of concepts but also to give impetus to some areas, raise awareness about emerging issues and forewarn about upcoming dangers if actions are not initiated by countries well in time.The talk will cover “How does the International System of Radiation Protection work” and inform about an International Action Plan on Radiation Protection of Patients of the IAEA. Is the international system binding or national systems are?. How harmonization is achieved through the work of the IAEA. Ultimately, the role medical physicists and health physicists in implementing the radiation protection requirements for staff and patient protection shall be discussed.Learning Objectives:1. To understand the system of radiation protection in international and national context2. To become familiar with international action plan on radiation protection of patients3. To become familiar with international organizations in the area of medical radiation protection4. To understand the potential role you can play in international activities
TH‐C‐220‐10: Limit of Setup Accuracy Using Bioluminescence Imaging to Guide Focal Pre‐Clinical Irradiation
Authors: Wong J , Armour M , Tuli R , Herman J , Artemov D , Patterson M 
Published: November 2011

Purpose: Cone beam CT (CBCT) on‐board new small animal radiation research platforms (SARRPs) is inadequate for guiding focal irradiation of targets in soft tissue. In this study, we examined the setup uncertainty using the more sensitive bioluminescence imaging (BLI) and BL tomography (BLT) for off‐line guided irradiation. Methods: A small glass bulb containing BL cells was implanted in six euthanized mice These were handled free‐hand while five others were immobilized. Surface BLI was acquired and BLT reconstructed of each carcass using a Caliper BLI system. An ink‐dot marked the “visual” centroid of the surface BL image. The carcasses were then transported to a SARRP for CBCT localization. In the visual setup, the animal was positioned to align the ink‐dot with the central axis of the SARRP. In the CBCT‐aided setup, the pose of each carcass was adjusted to recapitulate its pose at the time of BLI. The 2D radial offset of the “true” bulb centroid in CBCT from the central axis of the SARRP was measured. In the 3D setup, the 3D contours of CBCT and BLT contours were registered and the 3D radial offset between the 2 centroids was calculated. Results: The results are virtually identical between free‐hand and immobilized setup, as well as using visual and CBCT‐aided 2D setup. The onset of rigor mortis rendered immobilization un‐necessary. The 2D offset from the “true” position of the BL bulb was 2.3 +/− 1.3 mm. The 3D radial offset was 1.5 +/− 0.9 mm, approaching the documented uncertainty in BLT reconstruction. Conclusions: With the stiff carcasses, the results represent the best that can be achieved with off‐line 2D surface BLI and 3D BLT localization. An on‐board approach with further improvement in BLT using prior information of anatomic and optical properties, localization uncertainty less than 1 mm is possible.Funded in part by a sponsored research agreement from Xstrahl Ltd. Xstrahl Ltd. has a technology transfer Agreement with Johns Hopkins University.
Live Diatom Silica Immobilization of Multimeric and Redox-Active Enzymes
Authors: Sheppard V. C. , Scheffel A. , Poulsen N. , Kröger N. 
Published: November 2011

ABSTRACT

Living organisms are adept in forming inorganic materials (biominerals) with unique structures and properties that exceed the capabilities of engineered materials. Biomimetic materials syntheses are being developed that aim at replicating the advantageous properties of biominerals
in vitro
and endow them with additional functionalities. Recently, proof-of-concept was provided for an alternative approach that allows for the production of biomineral-based functional materials
in vivo
. In this approach, the cellular machinery for the biosynthesis of nano-/micropatterned SiO
2
(silica) structures in diatoms was genetically engineered to incorporate a monomeric, cofactor-independent (“simple”) enzyme, HabB, into diatom silica. In the present work, it is demonstrated that this approach is also applicable for enzymes with “complex” activity requirements, including oligomerization, metal ions, organic redox cofactors, and posttranslational modifications. Functional expression of the enzymes β-glucuronidase, glucose oxidase, galactose oxidase, and horseradish peroxidase in the diatom
Thalassiosira pseudonana
was accomplished, and 66 to 78% of the expressed enzymes were stably incorporated into the biosilica. The
in vivo
incorporated enzymes represent approximately 0.1% (wt/wt) of the diatom biosilica and are stabilized against denaturation and proteolytic degradation. Furthermore, it is demonstrated that the gene construct for
in vivo
immobilization of glucose oxidase can be utilized as the first negative selection marker for diatom genetic engineering.