bluuebunny/crossref_metadata_2025_split huggingface dataset:
WE‐D‐220‐06: Sono‐Contrast Spectroscopy for Breast Cancer Diagnosis: Clinical Study Results
Authors: Yan K , Liao L , Yu Y 
Published: November 2011

Purpose: to demonstrate the effectiveness of a non‐invasive multimodal sono‐contrast spectroscopy system in breast cancer diagnosis. Methods: This multimodal spectroscopy system combines three modules: diffuse reflectance spectroscopy (DRS), ultrasonography and low intensity focused ultrasound (LIFU). This multimodal system reports the optical functional difference in breast cancer and in normal tissue/benign lesion after transient LIFU stimulation of the vascular network. An IRB‐approved clinical study has been carried out to evaluate its diagnostic power. Currently 33 patients were enrolled with informed consent, grouped into histologically‐proven cancer, benign mass, and breast tissue, respectively. The ratio of intensities at wavelengths 685nm and 830nm was decomposed into low frequency and high frequency components using wavelet technique. Results: Comparison of the high‐frequency component showed that LIFU stimulated transitory fluctuation in non‐cancer tissue, but not in malignant tissue, as quantified in terms of the variance. The ratios of the variance during LIFU vs. baseline in cancer, benign and breast tissue are [mean (max/min/std)] 1.18 (2.04/0.60/0.45), 2.22 (2.74/1.51/0.54) and 3.21 (6.64/1.20/1.27), respectively. This suggests that the high‐frequency fluctuation was amplified in non‐cancer tissue during LIFU stimulation. Statistical analysis also reveals that these ratios of variance induced by LIFU are significantly different in cancer vs. non‐cancer (p=0.0007), and cancer vs. benign tissue (p=0.006). So far it has not suggested significant difference in benign vs. breast tissue (p=0.06). Conclusions: Current clinical results demonstrate the potential of the multimodal system in characterizing cancer vs. non‐cancer tissues. LIFU appears to exert more pronounced influence on blood flow in non‐cancer tissue than in breast cancer. This lack of response to LIFU in breast cancer is possibly due to its abnormal blood vasculature. The clinical study is ongoing to further assessing correlating factors, such as histological tissue types, hormone status (age), breast density, and to define the sensitivity and specificity of this promising technique.This work is supported by National Cancer Institute grant R33‐CA107860.
WE‐E‐BRA‐02: Methodological Issues and Key Results in the QUANTEC 2010 Review of Radiation‐Induced Normal Tissue Toxicity
Authors: Deasy J , Bentzen S , Constine L , Eisbruch A , Jackson A , Marks L , Haken R Ten , Yorke E 
Published: November 2011

The QUANTEC review of radiation‐induced normal tissue toxicity provides an attempt to synthesize published knowledge about normal tissue dose volume effects for many endpoints of clinical importance. In this review, I will briefly review the methods used by the QUANTEC group, limitations of the data, and some of the key findings. The QUANTEC reviews, although valuable, were constrained by several important limitations, for example: lack of access to the original data for joint analyses, differences in reporting methods, differences in dose calculation methods, differences in endpoint definitions, differences in endpoint measurement methods, etc. Despite these problems, some clinical recommendations have already been tested in separate data sets and shown to have validity. The solidity of the underlying data and clinical recommendations therefore necessarily varies. I will also briefly discuss recommended future directions to improve NTCP model predictions, including biomarker development, machine learning modeling, and pooled data analyses.Educational goals include:1. Understanding the main methods and structure of the QUANTEC reviews2. Understanding the variability of the review results3. Reviewing the main results, and caveats regarding their clinical use.
WE‐E‐301‐01: Practical Tips for VMAT Implementation
Authors: Galvin J , Yin F , Wu Q , Xiao Y 
Published: November 2011

Volumetric modulated arc therapy (VMAT) is an arc‐based dose delivery approach that produces highly conformal dose distributions similar to those generated with static gantry intensity modulated radiation therapy. Like many existing IMRT approaches, this treatment technique can be delivered with a standard linear accelerator that is equipped with a conventional multileaf collimator (MLC). During arc beam delivery the dose rate, the speed of the gantry, and the position of the MLC leaves are varied dynamically. The AAPM has a working group, under the Therapy Physics Commitee of the Science Council, preparing a report that provides general guidelines and recommendations for safe, error‐free use of this new technology. This presentation will review the information in the report of the Therapy Emerging Technology Assessment Working Group (TETAWG). A major advantage of this IMRT approach is the speed of dose delivery. This makes VMAT ideally suited for meeting the challenges of delivering the higher daily doses that are necessary for the hypofractionated treatment techniques. All accelerator manufacturers that use a traditional rotating gantry geometry have implemented this technology, and an additional number of treatment planning systems are now available to handle this part of the VMAT dose delivery process. The development of this technology is rapid and there is a great need for clearly describing the overall QA requirements for VMAT. This presentation will address this need by discussing Acceptance Testing, Commissioning, and ongoing QA methodologies for VMAT.Objectives:1. To understand the Acceptance Testing procedure for a new VMAT delivery system, a retrofitted VMAT cability, or a VMAT threatment planing system2. To understand the Commissioning process for the situations listed above3. To understand the requirements for ongoing routine QA for VMAT
WE‐E‐220‐08: Image Based Microwave Focusing for Transcutaneous Therapy in Combination with Focused Ultrasound Heating
Authors: Stang J , Moghaddam M , Kripfgans O , Fowlkes J , Carson P 
Published: November 2011

Purpose: In the current standard‐of‐care treatments for breast cancer, there remains a need for the reduction of local recurrence, harmful side effects, and cosmetic harm. high‐intensity focused ultrasound (HIFU) is generally effective but slow for large target areas and requires precise guidance. A combined microwave/ultrasound transcutaneous thermal therapy system is being developed for fast targeted or targeted plus diffuse treatment of breast cancer. Methods: In the microwave component, a cylindrical array of antennas operating at 915 MHz is used to focus continuous‐wave microwave energy transcutaneously into the pendent breast suspended in a coupling medium. The compatible HIFU system consists of two half shell arrays (Imasonic, Inc., Besancon, France) that allow close approach to the chest wall. In each case, prior studies provide breast tissue properties and distributions, for incorporation into multiphysics models. Time‐ reversal techniques are employed to find a solution (relative amplitudes and phase) for microwave focusing at a given location, and to precondition a weighted inverse solver that can optimize treatment planning for ablation at the tumor location while minimizing thermal dose elsewhere in the breast. Results: A full‐wave forward model of the microwave therapy array has been created and breast phantoms (E. Zastrow, //uwcem.ece.wisc.edu/MRIdatabase/) imported. Coupling of the electromagnetic energy deposition to the bioheat equation has been achieved using COMSOL Multiphysics, and a temperature map within the breast accounting for perfusion effects has been modeled. Studies of time‐reversal focusing results have shown that therapeutic levels of heat deposition with good targeting accuracy can be achieved using a twelve element array. Ultrasound beam patterns are close to predictions. Initial study of coupling agents compatible with both fields and with shared apertures is promising. Conclusions: Based on these encouraging results, the design and fabrication of adaptively focused combined laboratory systems are proceeding.Supported in part by DOD/BCRP W81XWH‐10‐1‐0730.
WE‐G‐BRB‐01: Safety and Quality Assurance in SRS and SBRT
Authors: Jaffray D , Benedict S , Solberg T 
Published: November 2011

Stereotactic radiosurgery (SRS) has been an effective modality for the treatment of benign and malignant cranial disease for over 50 years. Increasingly, the stereotactic approach is being applied in a number of extracranial disease sites. Stereotactic body radiation therapy (SBRT) holds significant potential for improving tumor control rates across a range of locations and histologies. SRS / SBRT are fundamentally different from conventional radiotherapy in that the intent is to deliver an ablative dose that overcomes all of the abilities of a cancer cell to defend itself. It is inherently aggressive, much like a surgical approach, and therefore an increased rate of acute complications compared with conventional radiotherapy could be expected. Both SRS and SBRT require specialized technology, meticulous procedures, and dedicated personnel. Several recent high‐profile medical radiation events have generated considerable attention within the media, and serve to remind the profession that close attention to safety and ongoing quality improvement is a fundamental responsibility. The main aim of this symposium will be to address safety and quality in SRS and SBRT, highlighting the errors that have occurred in the past and determining how they can be minimized in a systematic way, starting from patient simulation, to planning and verification, immobilization and localization, delivery, and patient follow‐up, and to provide some recommendations for SRS / SBRT processes and procedures that may be beneficial in understanding and reducing risks inherent to the modalities. Specific issues to be addressed include:‐ An overview of the accuracy requirements and the need for high levels of safety and quality in SRS/SBRT, as summarized in recent AAPM, ASTRO and ACR reports.‐ Highlights from recent media events related to SRS, examining what went wrong and why; what could go wrong; and what nominal safety procedures, commissioning and routine QA and testing are needed for SRS and SBRT programs to ensure errors are minimized.‐ Verification requirements for accurate image‐based localization and delivery in both rigid sites (e.g. CNS, spine) and moving targets (e.g. thorax (lung), liver, pancreas, etc.).
WE‐G‐BRC‐02: A Portable Optical CT Scanner for Interactive Teaching of Imaging Principles
Authors: Battista J , Miller J , Taylor R , Jordan K , MacDonald I 
Published: November 2011

Purpose: To develop a portable scanner that demonstrates the principles of radiography and computed tomography (CT). Methods: The traditional methods for teaching the physics of medical imaging rely on lectures, followed by demonstrations on a clinical system that is not easily accessible or programmed for educational purposes. We have developed a scaled‐down portable CT imaging system suitable for interactive “real time” demonstrations using a laptop computer during a classroom or lab session. Our optical system uses light rays in lieu of x‐rays so that experiments can be conducted while posing no electrical or radiation hazards to instructors and students. The desk‐top CT imaging device will be supplied with a learning kit of experimental test phantoms, lab manuals, instructional videos, and specialized software that demonstrate 2D radiographic and 3D CT image reconstruction methods. These approaches are relevant to imaging systems used in digital diagnostic imaging and image‐guided therapy. Results: A low‐cost portable system (< $15,000) has been manufactured (http://www.deskcat.com/) to enrich the studentˈs learning experience and improve the retention of fundamental imaging concepts. Students learn about spatial resolution, contrast resolution, system linearity, image artifacts and they perform quantitative measurements in 3D space, using image visualization software tools and specialized test phantoms (7.2 cm diameter × 5.3 cm long). Early reaction from instructors and students alike has been very encouraging. Conclusions: This learning package should prove attractive to universities with medical physics programs in Departments of Physics, Medical Biophysics, or Biomedical Engineering, as well as Medical Schools with residency training programs (Medical Imaging, Radiation Oncology). The systemˈs modular nature allows extensions for future coverage of related topics such as nuclear and molecular SPECT imaging. Through future developments, it may also be possible to model the dose deposition patterns from intensity‐modulated radiotherapy beams using ultraviolet exposure of radiochromic gel volumes.This research was sponsored by the Ministry of Research and Innovation, Government of Ontario, Canada (ORDCF Grant, OCITS Project) and by Modus Medical Devices as the industry partner. We also thank The University of Western Ontario for providing funding through its “Fellowship for Teaching Innovation”. This supported one of the authors (RT) during a summer studentship.
WE‐G‐214‐09: Validation of 4D‐CT Pulmonary Ventilation Imaging: Characterization of the Reproducibility
Authors: Yamamoto T , Kabus S , Berg Jvon , Lorenz C , Loo B , Keall P 
Published: November 2011

Purpose: A novel ventilation imaging method based on 4D‐CT has been applied to functional radiotherapy planning and assessing radiation‐induced ventilation changes. Understanding of its reproducibility is a prerequisite for such applications, however it has not been studied to date. The purpose of this study is to develop a method for validating 4D‐CT ventilation imaging through characterizing its reproducibility and show preliminary results. Methods: 4D‐CT ventilation images were created for three patients from repeat 4D‐CT scans at different time points, including two pre‐treatment (pre‐RT1 and pre‐RT2), one mid‐treatment (mid‐RT) and/or one post‐treatment (post‐RT). The reference (pre‐RT1) was compared with pre‐RT2 to quantify the temporal change in the absence of therapeutic intervention. Pre‐RT1 was also compared with mid‐RT and/or post‐RT to quantify the temporal change in the presence of therapeutic intervention. Finally, the Spearmanˈs voxel‐based correlations between pre‐RT1 and pre‐RT2 were compared to those between pre‐RT1 and mid‐RT or post‐RT to investigate the hypothesis: the temporal change in the absence of therapeutic intervention is smaller than that in the presence of therapeutic intervention. Results: Differences between the temporal changes in the absence and presence of therapeutic intervention were inconsistent. Regions of both agreement and disagreement were identified throughout the lung between pre‐RT1 and pre‐RT2, mid‐RT or post‐RT. The correlations with pre‐RT2 (absence) (range, 0.41–0.64) were slightly higher than or comparable to those with mid‐RT or post‐RT (presence) (range, 0.42–0.62). In general, the ventilation variations between pre‐RT1 and pre‐RT2 increased with increasing respiratory variations during the 4D‐CT acquisition. Conclusions: Preliminary results from a 3‐patient study suggest inconsistent differences between the temporal changes of 4D‐CT ventilation in the absence and presence of therapeutic intervention. Respiratory variations have been found to contribute to deteriorate the reproducibility. Ongoing studies focus on investigating more patients and spatial characteristics of the temporal changes.SK, JB and CL are employees of Philips Research Europe.
WE‐G‐110‐02: A Cascaded Systems Model for Imaging Performance and Task‐Based Optimization in Dual‐Energy Cone‐Beam CT
Authors: Gang G , Prakash P , Zbijewski W , Stayman J , Siewerdsen J 
Published: November 2011

Purpose: Optimization of dual‐energy (DE) tomographic imaging performance is challenged by the vast number of parameters to be considered. This work establishes a quantitative framework for theoretical analysis of noise‐power spectrum (NPS) and task‐based detectability in DE cone‐beam CT (DE‐CBCT). The model is compared to experimental results and applied to task‐based optimization of dual‐kVp selection and minimization of radiation dose. Methods: The model combines established methods for NPS propagation in DE imaging and CBCT, yielding a new framework for optimization of the DE‐CBCT imaging chain. The resulting DE‐CBCT NPS and noise‐equivalent quanta (NEQ) were derived to compute the detectability index for a variety of tasks in contrast‐enhanced musculoskeletal imaging. Theoretical calculations were validated against experimental measurements on a DE‐CBCT bench simulating the geometry of a CBCT prototype under development for musculoskeletal radiology. Optimization parameters included kVp pair, added filtration, dose allocation, etc. Results: The model provided tremendous insight in competing factors of DE‐CBCT performance. DE contrast (e.g., signal difference in 1 mm Ca or iodine to soft‐tissue) favored wide energy separation (e.g., [50/140] kVp) whereas NEQ degraded with kVp (e.g., maximized within the range considered at [65/100] kVp, with 0.6 mm Ag added to the latter). Detectability index quantitatively factored such tradeoffs in contrast and spatial‐frequency‐dependent noise along with the dose and imaging task — e.g., optimum at [65/105] kVp for a delta‐function iodine detection task. The model provided a quantitative guide to optimizing a broad scope of factors that would be difficult to consider through experimentation alone. Conclusions: A task‐based cascaded systems model establishes a new, quantitative framework for systematic optimization of DE‐CBCT imaging performance. The model combines established models shown to be of value in DE imaging and CBCT and should provide a valuable foundation for the development, optimization, and translation of high‐quality DE‐CBCT imaging techniques.This work was supported by the National Institutes of Health Grant No. R01‐CA‐112163.
WE‐G‐220‐01: Thermal Dosimetry Issues in Thermal Therapy
Authors: Stafford R 
Published: November 2011

Minimally invasive thermal therapies deliver heat to tissue in a controlled manner in order to modulate a host of microscopic and macroscopic events in tissue. Irreversible tissue damage from heating is a cumulative process that depends on exposure time as well as temperature and is often an endpoint for thermal therapies, particularly thermal ablation. Models for predicting the extent of damage after exposure to heat have been implemented and investigated in cells and tissue. With respect to rapid, high temperature ablations, the most often used approaches include simple temperature threshold models, Arrhenius rate models, and cumulative equivalent minutes at 43°C (CEM 43°C). While displaying significantly different responses at lower temperatures or long exposure times, these approaches are more closely related at higher temperatures.In cases where the ability to visualize the spatiotemporal distribution of heat and resulting damage is realizable, comparisons between these models are possible and useful for comparing with results from imaging and/or pathology correlates. Here we provide a review of the different models for high‐temperature ablations and use magnetic resonance temperature imaging results of thermal ablations, compared to with post‐treatment imaging or histology to illustrate some of the differences between these models when used for predicting outcomes in thermal therapy. Implications for therapy monitoring and guidance are discussed as are future prospects for predicting iso‐effects other than tissue destruction in tissue.Educational Objectives:1. Learn basic concepts of thermal dosimetry2. Understand current usage and potential limitations of applying current models
TH‐A(SAM)‐211‐01: Absorbed Dose Estimation with Internal Emitters
Authors: Williams L 
Published: November 2011

The fundamental equality used in internal emitter absorbed dose (D) estimation is D = S*Ã. Here, D and Ã are vectors and S is a rectangular matrix. Generally D and Ã have components assigned to the various body organs. Voxel‐based calculations are also possible if data are obtained in a 3‐D format. The first step in making the estimate is to perform activity (A) measurements in each of the organs that can be visualized in the scanning and/or imaging process. Essentially 6 methods are available for this quantification ranging from inverse‐square counting to quantitative SPECT (QSPECT) or PET. The most common technique is the geometric‐mean method (GM) which requires that two images be acquired simultaneously on each side of the patient. Given a set of counts for each source organ over time A(t), one must integrate numerically to find Ã. It is standard procedure to represent data at times beyond the last imaging point as a physical decay using the half life of the radiolabel. We should note that some agents used for Targeted Radionuclide Therapy (TRT) may not give off photons so that a surrogate agent is used; e.g., 111‐In‐antibody in lieu of 90Y‐antibody.Given the Ã vector, the estimator then may use S in two types of computations. A type I computation involves using the S matrix obtained from a relevant humanoid phantom. In this case, all organ sizes are specified for a standard man, woman or child and the biological data (Ã) from each animal or patient must be normalized accordingly. Type I calculations are used in regulatory applications and in comparing one agent with another scientifically. Type II computations are patient‐specific in that Ã is unchanged, but S must be modified to represent the geometry of the individual. In TRT, Type II estimates are made with relatively small amounts of activity prior to the start of therapy. Generally, human S values are standard tabulations available in OLINDA and other software. If murine dose estimates are needed, however, some S values are available. The result of the matrix multiplication of S and Ã is a set of doses for each of up to 30 or more target tissues. Because of external beam precedents, it is now becoming common to use both D and D2 in the analysis of tumor regression and normal organ toxicity. In this analysis, one plots the clinical outcome, such as tumor size, vs. a quadratic polynomial in dose. One anticipates a sigmodal response. Using such analyses, it is possible that TRT can evolve into a clinical strategy beyond its present limitation to B‐cell lymphomas.Learning Objectives:1. Knowing methods to determine organ activity.2. Realizing the errors in activity measurement.3. Understanding the types of dose estimate (phantom vs patient).4. Using dose as a first step in estimation effectiveness of therapy.