bluuebunny/crossref_metadata_2025_split huggingface dataset:
WE‐B‐330A‐01: Shielding Design Workshop: PET/CT
Authors: Martin M , Frey G 
Published: July 2006

The application of the structural shielding design techniques and goals as outlined in AAPM Task Group Report 108: PET and PET/CT Shielding Requirements Medical Physics (Vol. 33., Issue 1 (2006)) will be the basis for this practical course. As the use of PET and PET/CT units expands rapidly in the medical arena, the requirements for providing adequate radiation protection for both occupational personnel in these facilities and the public in uncontrolled areas around them necessitate the involvement of a qualified medical physicist. The many areas involved in implementing a PET/CT program including the Hot Lab, Patient Uptake Rooms, Patient Restrooms, Scan Rooms, and Disposal areas will be used as practical examples of typical structural shielding designs and evaluation methods. The testing of PET shielding insures that the shielding is properly installed and that individuals do not exceed the radiation exposure levels required by applicable regulations and ALARA policies. Testing of PET and PET/CT shielding is a complex multidimensional problem since there are multiple sources and the radiation is emitted isotropically from the patients. Thus efficient testing can both save time and reduce radiation exposure to the physicists doing the testing. This course will discuss efficient methods for shielding testing. It will also review the instrumentation available to physicists for making the measurements. Practical methods of testing of a PET/CT facility will be presented.Educational Objectives:1. Understand the exposure factors to be used for currently used PET isotopes to determine required structural shielding to meet exposure limits for occupational personnel and the public.2. Understand the effectiveness of existing and additional structural shielding materials that provide radiation protection and methods to calculate the required amounts of these materials.3. Understand the methods to be used to evaluate the adequacy of PET and PET/CT installations to insure adequate shielding has been provided to meet applicable state and ALARA requirements.
WE‐B‐ValA‐01: Interventional Fluoroscopy Imaging Equipment — What to Know Before You Buy
Authors: Cusma J 
Published: July 2006

The number of fluoroscopy‐guided interventional procedures performed continues to grow, accompanied by an increasing complexity in these clinical procedures. Technical improvement in the x‐ray imaging equipment utilized for these procedures continues at a fast pace as well, driven in part by the clinical requirements but also by the overall advance of computational technology. It remains a challenge for an interventional laboratory to ensure that its imaging equipment provides state‐of‐the‐art capabilities in a manner consistent with internal workflow and economic factors. The situation is further complicated by the fact that the replacement cycle for this equipment can be on the order of a decade ‐ an extraordinarily long time in the arena of technological advances. These factors place a high premium on careful analysis of the requirements and technical capabilities of the fluoroscopic and angiographic equipment being considered by a laboratory for purchase.The primary factors to be addressed in the purchase of modern interventional x‐ray imaging equipment remain the same as with any imaging equipment: the type of clinical procedures for which the equipment will be utilized. Since traditional clinical boundaries continue to evolve, equipment must be flexible to perform a range of procedures throughout a patient's anatomy. The specific concerns are the combination of cardiac, peripheral vascular, and neurovascular procedures to be performed. The answer to that question will have significant implications for the size of detector, image acquisition parameters, image processing options, and the display and storage requirements. As noted, the replacement cycle is long and these systems are not easily upgraded after purchase so identification of the procedure mix is important at the outset.Once the procedure requirement is determined, equipment can be evaluated with regard to how well it meets those requirements. Among the options related to the type of procedure are type of detector, field‐of‐view, x‐ray tube capacity, and image processing options. Functionality relevant for all types of procedures include: (i) patient exposure monitoring and exposure reduction methods; (ii) image analysis and quantification; (iii) storage capacity; (iv) options for archive and display. In addition, local factors such as service and maintenance must also be considered.Educational Objectives:1. Understand the relationship between clinical procedure requirements and the corresponding capabilities of interventional fluoroscopy equipment.2. Understand the range of options available in fluoroscopy and angiography x‐ray systems.3. Be able to assess and compare different imaging systems and prioritize local factors important for purchase decisions.
WE‐B‐ValB‐01: Physics Procedures for ACR MRI Accreditation
Authors: Keener C 
Published: July 2006

In recent years, the American College of Radiology (ACR) Magnetic Resonance Accreditation Program (MRAP) has been adopted by over 3000 sites, nearly half of the estimated MRI facilities in the United States. Those sites agree to follow a weekly QC program set up and monitored by a qualified medical physicist or MR scientist. They also agree to undergo initial and annual equipment performance evaluations by a qualified medical physicist/MR scientist. There are several published documents, including the ACR Phantom Testing Guidance and the 2004 ACR MRI QC Manual, which describe the tests and the performance criteria. These documents are helpful in providing guidance on submitting phantom images for accreditation. However, they allow considerable discretion to physicists doing these tests, and the scanners change more frequently than the published guidance.A consulting medical physicist may see a variety of scanners, each for a short period of time, and needs to provide the sites with useful recommendations beyond the pass/fail status of the phantom tests. The physicist must gather this information from existing data and tests performed with the ACR and other available phantoms. This lecture will describe information which can be derived from those data and how it may be used for improving MR image quality.Educational Objectives:1. Learn the current status of the ACR MRAP program and the role of the medical physicist in that program.2. Understand how to perform required phantom and annual tests on various scanners and the performance criteria for those tests.3. Understand how the results of those tests can be combined and analyzed to troubleshoot problems.4. Understand how QC test and phantom availability and results may vary depending on scanner manufacturer.
WE‐C‐330A‐04: Effect of Projection Angles Used in Multi‐View Reconstruction (MVR) Using Images From a Microangiographic (MA) Detector and An Image‐Intensifier (II) System
Authors: Patel V , Kuhls A , Noël P , Walczak A , Ionita C , Chityala R , Tranquebar R , Rangwala H , Kasodekar S , Yadava G , Hoffmann K , Bednarek D , Rudin S 
Published: July 2006

Purpose: The sensitivity of a new 3D Multi‐View Reconstruction (MVR) angiography technique to the projection angles used is evaluated by comparing 3D centerlines calculated from combinations of three projections acquired from two imaging systems with that from micro‐Cone Beam CT (μCBCT), which is taken as truth. Method and Materials: A 3D centerline of a contrast‐filled carotid vessel phantom was reconstructed from image data acquired using a custom‐made μCBCT system with a microangiographic (MA) detector (45 μm pixels, 4.5 cm field‐of‐view (FOV)). Projection images of the same phantom were also acquired using the MA and an image intensifier (II) detector system (120 μm pixels, 4.5 in FOV) on a C‐arm x‐ray unit. The MVR technique was used to compute 3D centerlines for 12 combinations of projection angles. Each 3D MVR centerline was aligned with the μCBCT “true” 3D centerline using a Procrustes technique, and a root‐mean‐square (RMS) deviation was calculated. Results: The average RMS deviation for the MA‐MVR centerlines is 25 μm with a standard deviation of 3 μm over the 12 different projection‐angle combinations, whereas the average RMS deviation for the II‐MVR centerlines is 41 μm with a standard deviation of 4 μm over these same combinations. The RMS deviation as a percent of the internal vessel diameter, 0.75 mm, is 3.3% for the MA and 5.5% for the II and appears to be independent of view selection. Conclusion: For the MVR technique, the improved resolution of the MA resulted in improved centerline determination compared to the II system. For both detectors, the selection of a particular projection set had little effect on the RMS centerline deviation. The low RMS deviations for both detectors indicate that the MVR technique can provide accurate 3D centerlines.(Partial support from NIH Grants R01‐NS43924, R01‐EB02873, R01‐HL52567, R01‐EB02916, and Toshiba Medical Systems Corporation).
WE‐C‐330D‐03: Bioinformatics, the Multiple‐Biomarker Classifier Problem, Complexity, and Uncertainty
Authors: Wagner R F 
Published: July 2006

The most celebrated landmark of modern bioinformatics has been the sequencing of the human genome. Early in the project it was commonly believed that humans have about 100,000 genes and as the project neared completion the estimates came down into the neighborhood of 25,000–30,000. Hidden Markov Models (HMM) are used to carry out statistical parsing of the “linguistics” of such bioinformation. Such massively complex analysis has been facilitated by modern developments in massively complex hardware and software—but such analysis is naturally accompanied by great uncertainties. At a lower level of complexity are the algorithms used for computer‐aided diagnosis in medical imaging, and at an intermediate level are the tools under current development for fusing multiple biomarkers—for example, from a large number of spectral lines in mass spectroscopy of protein fragments in blood samples and other mutliplex data from protein and gene microarrays. This talk will review the uncertainties in measured performance of such diagnostic tests as a function of the sample sizes available for training and testing as well as the dependence on the number of fused biomarkers and the complexity of the associated statistical learning algorithm. A strategy for designing large trials based on pilot studies will be outlined.Educational Objectives:1. Understand the multiple‐biomarker classifier problem.2. Understand the uncertainties in its performance assessment due to finite training and testing.3. Understand the dependence on number of biomarkers and complexity of statistical learning algorithm.
WE‐C‐ValA‐02: The Impact of 4D Breathing Motion Effects Versus Tissue Heterogeneity in Lung Cancer Treatment Planning
Authors: Rosu M , Chetty I , Tatro D , Ten Haken R 
Published: July 2006

Purpose: To investigate the relative magnitudes and clinical importances of the dosimetric effects related to 4D breathing motion and tissue heterogeneity for thoracic tumors treatment planning. Methods: Scans were acquired at normal exhale/inhale breathing phases. The target was the union of the exhale and inhale GTVs, uniformly expanded by 5mm(ITV). Patients were planned with both AP/PA and 3‐D conformal plans using the exhale (“static”) dataset, assuming unit density, for 100±5% ITV dose coverage. Each of these plans was further used to calculate: (a) heterogeneous “static” dose; (b) homogeneous cumulative dose; (c) heterogeneous cumulative dose. The same number of MU were used for each of the calculations and was based on the homogeneous “static” plan. Cumulative dose distributions consisted of a time‐weighted sum of exhale and inhale doses. Doses were calculated using the DPM_MC code which includes secondary electron transport for the heterogeneous computations. Results: Relative to unit‐density plans, tumor EUD, and lung NTCP increased in the heterogeneity corrected plans; primarily due to the reduced beam attenuation through lungs and the larger than coin‐size tumors investigated. In comparing 4D cumulative dose plans with static plans, clinical EUD and NTCP estimates were relatively unchanged. The insignificant tumor EUD change was a consequence of good target design, while the small lung NTCP change was due to its large volume effect. Accounting for tissue heterogeneity resulted in average changes of 10% in MLD. Accounting for 4D breathing motion effects resulted in <1% changes in MLD from the static value. The magnitude of these effects was not correlated with the dose distribution conformality. Conclusions: In this study we found that tissue heterogeneity effects are likely to have a larger clinical significance on tumor (if ITV is properly designed) and normal lung clinical treatment evaluation metrics than occurs with 4‐D respiratory‐induced changes.Supported by P01‐CA59827, R01‐CA106770.
WE‐C‐ValB‐03: Functional Analysis of Tumor Vasculature Post Antiangiogenic Intervention with Argeted Anti‐VEGFR2 Therapy
Authors: Brown AS 
Published: July 2006

High frequency ultrasound biomicroscopy (UBM) permits in vivo assessment of anatomical and physiological parameters at high resolution. The ability to image the mouse noninvasively facilitates longitudinal studies with repeated measurements in the same animal over time, to follow normal development or disease processes as well as response to therapeutic intervention. Anatomical images are obtained using B mode, giving a cross‐section of the structure of interest. Anatomical changes can now be quantitated using 3D volumetric B mode imaging, and rendered to give an accurate contour of the structure of interest. 3D UBM may be used to measure organ growth through normal development, or to compare treated versus untreated populations in mouse models of human disease. High frequency ultrasound Doppler permits measurement of blood flow velocity in selected vessels of interest. Recent advances in blood flow analysis, including speckle variance analysis, permit investigation of blood flow velocity of flow velocities down to 100 microns per second, as well as perfusion alterations.High frequency ultrasound imaging modes, imaging strategies, and post‐processing methods used to generate anatomical and physiological data will be discussed.Educational Objectives:1. Understand the concepts behind high frequency ultrasound imaging modes.2. Understand the application of high frequency ultrasound to image development and disease processes in the mouse, including experimental design, data acquisition and data processing.3. Understand therapeutic study design, data acquisition and analysis using UBM.
WE‐C‐230A‐01: The Application of Error Reduction QA Philosophy in HDR Brachytherapy
Authors: Thomadsen B 
Published: July 2006

Routine quality assurance (QA) in brachytherapy developed quickly through the 1990s, and fairly standard practices became common. The reports of Task Groups 40, 56 and 59 established formalized, accepted standards for QA in brachytherapy, and textbooks covered QA procedures in detail (1). Why, with a solid understanding of QA procedures, were there still many reported brachytherapy medical events, and likely many more unreported or unrecognized? A review of such events (2) notes that for many cases, the facility had QA procedures in place, but they were ineffectual because they either did not cover the situations that evolved or, often, simply were not performed, frequently because of time constraints. Current high dose‐rate (HDR) brachytherapy QA focuses heavily on equipment and instrumentation. Very few events resulted from errors in the equipment (although, equipment failures often set the stage), due in part to the extremely high reliability built into the devices and, possibly in part, because of the attention paid to equipment QA by the medical physicists. A soon to be released report from the International Atomic Energy Agency will note that the greatest danger in radiotherapy is not equipment malfunctions but the human activities related to the procedures. (3) Much of the current QA for HDR brachytherapy stems from regulations of the Nuclear Regulatory Commission. Some of the regulations expend effort with little expected return. For example, daily QA requires a check of the door interlock at the room entrance. For many facilities, the operator has the door in clear view during treatments; the probability of a person trying to enter the room during a treatment with a failure of the interlock becomes vanishingly small. With each new source, the length and function of transfer tubes and applicators must be checked. Most of these instruments cannot change their length, and the functioning would be (and should be) determined at each use. Measuring exposure readings outside the HDR room with each source change wastes time. Such requirements divert resources from useful activities. The new paradigm for QA first assesses all the possible ways things can go wrong (and the list is a long one), rating the likelihood of occurrence, and severity of the result if it does happen, and the probability of detecting the failure before it propagates into the event. These ranking provide the priorities for allocating resources for activities to prevent failures This process will naturally place a greater emphasis on the human role in the procedures.Learning Objectives: To understand1. The problem with the current QA paradigm, and2. The advantage of the new paradigm
WE‐C‐230A‐02: The Application of Error Reduction QA Philosophy in IMRT
Authors: Palta J , Huq M 
Published: July 2006

The increasing complexity, functionality, and site‐to‐site variability of modern radiation therapy planning and delivery techniques challenge the traditional prescriptive quality control/quality assurance (QC/QA) programs that ensure safety and reliability of treatment planning and delivery systems under all clinical scenarios. The manufacturing industry has historically relied on extensive testing and use of techniques such as probabilistic reliability modeling for developing and maintaining new products. Among the most widely used method of risk analyses are Failure Modes and Effects Analysis (FMEA). This is a methodology for analyzing potential reliability problems early in the development cycle where it is easier to take actions to overcome these issues, thereby enhancing reliability through design. FMEA is used to identify potential failure modes, determine their effect on the operation of the product, and identify actions to mitigate the failures. From a manufacturer's perspective, FMEA is a valuable method to systematically evaluate a device design's potential for inducing user errors. User errors are defined as a pattern of predictable human errors that can be attributable to inadequate or improper design. When these risk analyses are done early in the development cycle, potential faults and their resulting hazards are identifiable and much easier to mitigate with error‐reducing designs. These risk management methods are excellent complements to other important user‐centered design best practices. Risk analysis, or hazard analysis, is a structured tool for the evaluation of potential problems which could be encountered in connection with the use of a device. The early and consistent use of FMEAs in the design process allows the engineers to design out failures and produce reliable and safe products. FMEAs also capture historical information for use in future product improvement.We will first review current paradigms of QC/QA issues in IMRT with a goal to define the problems and challenges associated with the implementation of traditional methods of quality assurance. This will be followed by a second presentation, which will describe a step‐by‐step implementation of the aforementioned hazard analyses and error mitigation methodologies of industrial engineering in addressing QA/QC and safety issues in IMRT. Such an approach should result in a QA/QC program for IMRT that has a good scientific rationale and justification.
WE‐C‐224C‐04: Correlated Sampling for Accelerating CT‐Based Monte Carlo Dose Calculations for Brachytherapy Treatment Planning
Authors: Le Y , Todor D , Williamson J 
Published: July 2006

Purpose: To investigate the potential of correlated sampling variance reduction technique for accelerating CT‐based Monte Carlo (MC) simulations for calculating 3D brachytherapy dose distributions.Method and Materials: Correlated MC (CMC) simulations generate photon histories in the homogeneous geometry. By recomputing particle weights to account for non‐water composition of the CT voxels and applicator and seed components, a second highly correlated set of histories is constructed, resulting in a lower variance estimate of the dose difference, ΔD=Dhet‐Dhom To evaluate the accuracy and efficiency of CMC, a clinical permanent prostate implant with 78 I‐125 seeds was simulated using both CMC and UMC versions of our accelerated CT‐based MC dose‐computation code, PTRAN_CT for voxel sizes ranging from 1×1×1mm3 to 2×2×2mm3. Mean efficiency gains were estimated for regions with minimum doses greater than 20%, 50% and 90% of D90, as well as different anatomical regions.Results: Systematic differences between UMC and CMC PTRAN_CT were less than 0.4%. Efficiency gains ranged from 4.68 to 15.76 depending on the voxel size and region. CMC can achieve a 2% average precision with 2 mm cubic voxels in 23 seconds on a single P4 processor for voxels with doses > 50%D90. Voxels with very low doses and/or large dose perturbations can experience efficiency losses. Because ΔD is a relatively smoothly varying quantity compared to Dhet, CMC efficiency maybe enhanced using coarser voxel sizes than UMC for the same level of volume‐averaging artifact. Conclusion: Correlated sampling MC can reduce CPU times by an additional 4–15 fold compared to accelerated uncorrelated MC. In practice, larger efficiency enhancements can be achieved because correlated sampling volume‐averaging errors are smaller. MC‐based brachytherapy treatment planning, requiring only a few seconds of CPU time, is achievable. (Supported by NIH‐R01CA46640).
WE‐C‐224A‐02: Radiation Induced Cancers in Treated Patients
Authors: Suit H 
Published: July 2006

The increasing numbers of radiation treated patient surviving for long periods forces an assessment of their risk of radiation associated cancer. Dose response relationships for cancer induction in the laboratory mice varies with strain, gender, tissue/organ of concern, observation period, dose fractionation and LET. For most experiments, risk increased with dose in an orderly manner. However, in some large experiments on mice and one on Macaca mullata, there was no evident increase risk of cancer at 1–2.Gy single dose WBI. These studies were life span and autopsy examinations.Risk of death due radiation induced solid cancer among 86,611 survivors of the atom bomb explosions in 1945 [entered the study in 1950] increased throughout the observation period of 52 years. There have been 10,127 deaths due to solid cancer and of these, 479 [4.7%] have been attributed to the radiation exposure. The time distribution of these cancer deaths have been: 18%, 19.1%, 27.1% and 35.4 % for the periods 1950–67, 1968–77, 1978–87 and 1988–97. Namely, 35% of these radiation cancer deaths occurred at 42–52 years post irradiation.Data from 14 large and long follow‐up series of irradiated human patients demonstrate increased risk with dose for cancers of the stomach and pancreas; over the dose range 1–45 Gy. In contrast there was no evident increased risk of bladder or rectal cancer after doses of 1–60 Gy. For the studies on murine, canine, sub‐human and human subjects there is not a constant relative risk for the different organs, viz probability of a radiation cancer for a specified dose varies with the organ.Consideration will be given to the differential risk between photon [conformal and IMXT], proton [broad beam energy modulated and pencil beam scattered] and 12C ion beams.