bluuebunny/crossref_metadata_2025_split huggingface dataset:
TU‐B‐T‐6B‐01: Transition to Heterogeneity Corrections
Authors: Klein E , Stevens C 
Published: June 2005

With the publication of the AAPM's TG‐65 report on inhomogeneity corrections for photon beams, physicians and physicists must clearly understand how implementation of such corrections impact dose prescriptions. The TG report details the physics of the heterogeneity algorithms, methods to evaluate these prescriptions, limitations, and most importantly, how to implement. The report gives clear recommendations as to the dialogue needed before implementation takes place. A clinic should perform simultaneous plans by planning and treating the patient with no corrections applied. A simultaneous plan is generated that applies the correction ‘after the fact’, thereby leaving the homogeneous (and therefore given doses) intact. This will educate the staff as how prescriptions may (or may not) be altered according to the differences observed. In addition, planning volume margins may be affected according the algorithms' ability to calculate penumbra in the presence of inhomogeneous media, particularly lung. In addition, classic beam arrangements may need to be scrutinized due to the impact of increased exit dosing observed with corrections applied. MDAH found that implementation of inhomogeneity corrections was fairly easy to accomplish, even in a busy clinic. Accounting for heterogeneity resulted in better PTV coverage by changing beam weighting, without significantly changing isocenter dose. The distance from PTV to block edge also increased in some situations. Failure to account for tissue heterogeneity could lead to dose calculation errors, particularly to the PTV, which often results in significant underdosing. Accounting for tissue heterogeneity using many commercially available algorithms changes the dose to the PTV much more than will the future use of Monte‐Carlo‐based dose calculation algorithms. Heterogeneity corrections are particularly important when using IMRT, particularly in lung cancer treatment. They concluded that the benefits of accounting for tissue inhomogeneity vastly outweigh the minor difficulties with its implementation, will result in more accurate calculation of dose distributions, and hopefully in better outcomes for patients. The use of heterogeneity corrections also allowed the use of higher energy photon beams in 3D planning, because of greater confidence in dose calculation accuracy. This course will give direction along with caveats in applying inhomogeneity corrections from the perspective of physics and physicians. In addition, there will be a review of current algorithms commercially available, along with a historical perspective on how various stages of algorithms impacted the radiotherapy community on evaluating and using inhomogeneity corrections.Educational Objectives: The physicist will learn ‐1. the details of TG‐652. details on commercially available algorithms including limitations3. the MDAH approach to implementing corrections4. a historical perspective of studies on evaluating corrections5. TG‐65's recommendation plan for a clinic's implementation.
TU‐C‐T‐617‐04: Beam Configuration of Photon‐Based Stereotactic Radiosurgery
Authors: Wu X , Dooley J , Yang J , Persaud V , Bossart E , Shao H , Both J , de la Zerda A , Schwade J , Markoe A 
Published: June 2005

Purpose: Unequivocally, the experience of Gamma knife has set a solid notion pertaining to the definition and the dosimetric requirement of radiosurgery. Any newer, post‐Gamma knife, radiosurgery system has to demonstrate comparable targeting precision and sharp dose gradient characteristics. Statistics shows that the total of number of beams used in Cyberknife treatment is often less than 200. Herein, we present a study to evaluate the dose distribution characteristics comparing with that of the traditional photon‐based radiosurgery. Material and Method: An experimental beam path with beam positions (notes) distributed in 2Π solid angle was created to compare the dose distribution ofa. Single isocenter plan with different collimator sizes and with the total number of beams ranging from 30 to 205.b. Multiple isocenter conformal plan and non‐isocentric inverse conformal plan.c. Multiple non‐coplanar beam arrangement and Multiple coplanar beam arrangementResults and Discussion: For single isocenter plans, no significant differences were observed in isodose levels ranging from 90% to 10%, with number of beams ranging from 55 to 205, distributed over 2Π solid angle. With beam number reduced to 50, the noticeable differences fall in the dose levels under 10%. The conformal planning using multiple isocenters increases the number of beams geometrically, while no‐isocentric inverse planning can achieve excellent conformity with much less number of beams. However, close attention is needed to assure the dose fall‐off is well controlled in all directions. Although the reduction of beam number may not affect significantly the dose gradient in the median‐high dose region, to deliver all beams in a single plane does result in a much inferior dose distribution. The attempt to use a single co‐planar delivery for radiosurgery is thus to be avoided.
TU‐C‐W‐608‐01: Ultrasound QC Workshop
Authors: Kruger R , Lu Z , Miller H , Moore W , Goddu S 
Published: June 2005

This workshop will provide attendees an opportunity to observe ultrasound scanner operations and quality assurance procedures. A portable ultrasound unit and various ultrasound QC phantoms will be provided and used to demonstrate the QC procedures. A set of QC test procedures described in AAPM Ultrasound Task Group 1 Report (Medical Physics 1998;Vol 25: 1385–1406) will be presented, including display monitor fidelity, image uniformity, depth of visualization, horizontal and vertical distance accuracy, axial and lateral resolution, slice thickness, dead zone measurement. Demonstrations of test procedures and equipment will be performed by the instructors and industry representatives.Educational Objectives:1. To learn the effect of parameter settings on various aspects of ultrasound imaging.2. To observe the ultrasound quality control test procedures for real‐time B‐mode units.3. To become acquainted with various ultrasound QC phantoms.
TU‐D‐I‐609‐02: What to Expect When CAD Is Implemented Clinically
Authors: Nishikawa R 
Published: June 2005

I have developed a simple model to study the effects of computer‐aided detection (CADe) on screening mammography. The model incorporates tumor growth rate, the sensitivity of radiologists and the CADe scheme, how effectively the radiologist uses the CADe output, and the interval cancer rate. The model shows that the additional cancers detected when the radiologists uses CADe depends on how many cancers the radiologist misses without the computer aid, how many of the missed cancers the computer can detect, and what fraction of the computer detected missed cancers the radiologist will correctly recognize as a missed cancer. I also modeled the effect of CADe on radiologist false‐detection rate. Unless the computer can preferentially detect cancers over benign lesions, the increase in the number of cancers detected when using CADe will be the same as the increase in the number of women recalled (the vast majority of which will be false positives). This does not imply that CADe has no net affect. On the contrary, an equal increase in the cancer detection rate and the recall rate is consistent with radiologists operating on a higher ROC curve implying that CADe is improving the radiologists' performance. However, even if CADe was able to help radiologists reduce their miss rate by 50%, there will be only a 10% increase in the cancer detection rate before and after implementation of CADe. This increased is difficult to detect in practice because of the variable growth rate of tumors. The number of cancers present in a screened population will change year by year so that this variation can mask the actual increase in the cancer rate when CADe is implemented. However, the size of the cancers detected when using CADe is smaller than those detected by the radiologist when not using CADe.Educational Objectives:1. Understand the factors affecting the clinical effectiveness of computer‐aided detection2. Understand some of the difficulties of measuring the clinical effectiveness of computer‐aided detectionFinancial Disclosure: RM Nishikawa is a shareholder in R2 Technology, Inc. (Sunnyvale, CA). He also receives research funding and royalties from R2 Technology.
TU‐D‐J‐6B‐02: Optical Tomographic Imaging of Small Animals
Authors: Hielscher A 
Published: June 2005

Diffuse optical tomography (DOT) is emerging as a viable new biomedical imaging modality. Using visible and near‐infrared light, in the range of 500 to 900 nm, this technique can probe absorption as well as scattering properties of biological tissues. The main applications are currently in brain, breast, limb, and join imaging; however, the area of optical tomographic imaging of small animals is attracting increasing attention. This interest is mainly fueled by recent advances in transgenic manipulation of small animals that has led to many models of human diseases. Using these models it is possible to link specific genes, proteins, and enzymes to molecular, and cellular processes that underlie various disorders. In addition, the advent of novel biochemical markers that are sensitive to molecular processes, defect genes, and cell receptors, makes it for the first time possible to detect diseases on a molecular level long before actual phenotypical symptoms appear. Small animal optical tomography has several advantages over other, more traditional, imaging modalities. For example, optical markers emit low‐energy near‐infrared photons that are less harmful than more energetic gamma rays emitted from radioactive markers (used in SPECT and PET, for instance). This simplifies synthesis procedures and experimental designs and will be of particular importance for future applications in humans. Furthermore, optical methods typically offer higher sensitivity (as compared to MRI and SPECT) and are relatively inexpensive (as compared to PET, SPECT, and MRI). In this paper we will review underlying principles in optical tomographic imaging as they apply to studies involving small animals. We will describe the basic contrast mechanism involved in imaging of endogenous as well exogenous contrast agents. In addition we will discuss specific features and advantages of different types of optical instrumentation currently available, such as steady‐state, frequency‐domain, and time‐resolved imaging systems. Furthermore we will describe in detail the structure of commonly used image reconstruction schemes and algorithms and point to still existing challenges. Finally, we will provide an overview of the most recent literature in optical small animal imaging, specifically in the areas of blood oximetry, fluorescence and bioluminescence imaging.Educational Objectives:1. To understand significance, potential, and limits of optical tomographic small animal imaging.2. To understand the contrast mechanisms that underlie optical tomographic imaging.3. To understand the basic measurement instrumentation used in optical tomographic imaging.4. To understand the fundamental concepts and problems involving optical tomographic image reconstruction algorithms.5. To learn about the major applications of this novel technology.
TU‐EE‐A4‐01: Clinical Experience with a 3‐D Ultrasound Prostate Localization System
Authors: Orton N , Jaradat H , Tomé W 
Published: June 2005

Purpose: 3‐D ultrasound localization has been performed for external beam prostate treatments at our institution since September 2001. This poster presents an analysis of the daily shifts for 198 patients and 4855 fractions, and the results of tests performed to assess the system's performance and capabilities under clinical conditions. Method and Materials: All patients were treated supine, using a rectal balloon. Each day patients are initially aligned to skin marks placed by comparison of portal images with digitally reconstructed radiographs. An ultrasound image set is acquired using a 3‐D ultrasound localization system (Sonarray, Varian Medical Systems), and the patient may be shifted to account for variations in prostate position. Ultrasound images and shifts were stored for every fraction. Additionally, three tests are presented:• To assess the accuracy of the shifts, 7 patients treated on a helical tomotherapy machine were localized daily using both ultrasound and a megavoltage CT scan.• To assess the extent of intra‐fraction motion, ultrasound localization was repeated after treatment for 6 patients and a total of 29 fractions.• To assess the inter‐user variation in shifts, four experienced operators independently localized 5 patients for 5 consecutive fractions.Results: The mean daily shift for all patients was 7.4±3.8mm. Comparison of ultrasound to MVCT showed that ultrasound localization improved alignment: the mean ultrasound‐MVCT vector was 3.0±1.7mm, compared to 4.8±2.4mm between the MVCT and the skin marks. Intra‐fraction motion and inter‐user variation were found to be small in comparison with the daily shifts. The mean intra‐fraction prostate shift was 1.9±1.0mm, and the shift was within the 3mm imaging uncertainty of the system for 25 of 29 fractions. Conclusion: Our experience shows that 3‐D US localization can be a valuable tool for aligning external beam prostate patients, enabling the use of reduced margins and more aggressive fractionation schedules.
WE‐B‐I‐618‐02: Digital Image Displays — Resolution, Brightness, and Grayscale Calibration
Authors: Flynn M 
Published: June 2005

Digital radiographs from CR, DR, RF, and XA systems are displayed on monitors when the exam is performed, when a radiologist interprets the examination, and when the referring physician or surgeon review the image. The various monitors used typically vary in image quality. Display resolution is influenced by pixel size and viewing distance. Displayed field of view varies with the monitor array size and image zoom. Image brightness influences low contrast detection, peripheral vision, and may effect observer fatigue. The display grayscale influence contrast and may alter the appearance for different viewers unless matched on all monitors. The requirements for resolution, brightness, and grayscale are considered for various situations including RF and XA exam room displays, technologist QC stations, radiologists reading stations, general clinic review stations, surgical display, and conference case presentation.Educational Objectives:1. Understand how pixel size and viewing distance influence resolution in relation to visual limits of the human eye.2. Understand how image brightness influences observer performance.3. Learn how the grayscale characteristics of clinical display systems can be calibrated to match diagnostic systems.4. Learn the performance characteristics of displays now available for various applications.
WE‐C‐J‐6B‐02: Infrastructure for 4D Image Guide Therapy
Authors: McShan D 
Published: June 2005

This presentation looks at infrastructure needed for research investigation and for routine clinical use of time resolved volumetric (4D) image guided therapy The 4D imaging data used for IGRT comes from a variety of sources ranging from standard CT scanners, cone‐beam CT from gantry mounted imagers, MR, and PET images. An example of a reconstructed 4‐ D data set for CT would have dimensions (512×512×100×10) (100 slices per volume representing 10 different time intervals. This represents approximately 0.5 gigabytes of data. Daily acquisition of these images therefore represents significant storage demands and increased network speeds needed to communicate this data between various processes (image alignment tools, contouring/segmentation, and treatment planning). While the DICOM imaging standard can be used for storing 4D datasets, the related derive data such as deformable alignment parameters and other associated data such as statistics about anatomical variability and embedded marker positions, are beyond the standard and require establishment of separate bookkeeping to maintain that data. The actual use of 4D data varies. This data provides information about patient alignment and extent of physiological motion. However, 4D data can also provide time dependent functional information which may provide early indicators of tumor and normal tissue responses. Decision based on analysis of these functions can be employed for daily assessment and immediate adjustments to the treatment either before or during delivery. Or analysis of the 4D data may be used to provide statistical support for more deliberate plan adjustment decisions. Often 4D data implies geometrical changes over time such as heart and respiratory motion which require deformable alignment of image volumes to relate and track anatomical regions of interest between different motion states and in reference to the imaging volumes used for planning. To aid in this presentation, a survey of current research and clinical uses of 4D image guided therapy will be presented with answers to questions regarding : the types of 4D imaging data sets used, the sizes of typical data sets, the frequency of acquisition, storage demands (long term and short term) and algorithms used for reconstruction, registration, analysis, and compression. The survey results demonstrate infrastructure needs for 4D image guided therapy that are significantly above and beyond what is typically needed for static volumetric imaging and planning in terms of both the amounts of data acquired and the tools needed for data management and analysis, This survey has included manufacturers and leading researchers in the field. In addition to survey results, examples of the infrastructure implemented by these users will be shown.Educational Objectives:1. Identify various sources of 4D data and typical storage requirements2. Present various use of 4D for IGRT employed to date and associated data display and analysis tools3. Demonstrate successful infrastructure implementations
Using Herbal Medicine as a Means of Prevention Experience During the SARS Crisis
Authors: Lau T. F. , Leung P. C. , Wong E. L. Y. , Fong C. , Cheng K. F. , Zhang S. C. , Lam C. W. K. , Wong V. , Choy K. M. , Ko W. M. 
Published: June 2005

At the peak of the SARS epidemic in Hong Kong, hospital workers were under high risks of contraction of the infection. Herbal preparations had been used historically in China to treat influenza-like diseases. During the SARS outbreak, herbal preparations had been used jointly with standard modern treatment in China. As a means to protect the at-risk hospital workers, an innovative herbal formula was created and consumed by 3160 of them in two weeks. During the two weeks, symptoms and adverse effects were close monitored; 37 of them had their serum checked for immunological responses. The results showed that none of the herb consumers contracted the infection, compared to 0.4% among the non-consumers. Adverse effects had been infrequent and mild. There were hardly any influenza-like symptoms and the quality of life improved. In the group who volunteered to have their immunological state checked, significant boosting effects were found. It was concluded that there might be a good indication for using suitable herbal preparations as a means of preventing influenza-like infection. The mode of preventive effect could be treatment of the infection at its very early stage instead of producing a period of higher immunological ability, as in the case of vaccination.
Mosaicism of NK cells in a patient with Wiskott-Aldrich syndrome
Authors: Lutskiy Maxim I. , Beardsley Diana S. , Rosen Fred S. , Remold-O'Donnell Eileen 
Published: June 2005

AbstractRare cases of somatic mosaicism resulting from reversion of inherited mutations can lead to the attenuation of blood-cell disorders, including Wiskott-Aldrich syndrome (WAS). The impact of the revertant hematopoietic stem or progenitor cells, particularly their representation in blood-cell populations, is of interest because it predicts the outcome of gene therapy. Here we report an 8-year-old patient with WAS caused by a single nucleotide insertion in the WASP gene that abrogates protein expression. The patient nonetheless had mild disease. We found reversion of the mutation in a fraction of patient lymphocytes. Forty percent of natural killer (NK) cells expressed Wiskott-Aldrich syndrome protein (WASP), and NK cells contained both mutated and revertant (normal) sequences. WASP was not expressed in patient T or B cells; T cells contained only the mutated sequence. The selective advantage of WASP+ NK cells was also demonstrated for carrier females. The enrichment of WASP+-revertant NK cells indicates that WASP provides a selective advantage in this lineage and predicts the success of gene therapy for reconstituting the NK-cell compartment. The importance of reconstituting the NK-cell lineage is discussed. (Blood. 2005;106:2815-2817)
Transcription profiling of C/EBP targets identifies Per2 as a gene implicated in myeloid leukemia
Authors: Gery Sigal , Gombart Adrian F. , Yi William S. , Koeffler Chloe , Hofmann Wolf-K. , Koeffler H. Phillip 
Published: June 2005

AbstractCCAAT/enhancer-binding proteins (C/EBPs) are a family of transcription factors that regulate cell growth and differentiation in numerous cell types. To identify novel C/EBP-target genes, we performed transcriptional profiling using inducible NIH 3T3 cell lines expressing 1 of 4 members of the C/EBP family. Functional analysis revealed a previously unknown link between C/EBP proteins and circadian clock genes. Our microarray data showed that the expression levels of 2 core components of the circadian network, Per2 and Rev-Erbα, were significantly altered by C/EBPs. Recent studies suggested that Per2 behaves as a tumor suppressor gene in mice. Therefore, we focused our additional studies on Per2. We showed that Per2 expression is up-regulated by C/EBPα and C/EBPϵ. Per2 levels were reduced in lymphoma cell lines and in acute myeloid leukemia (AML) patient samples. In addition, we generated stable K562 cells that expressed an inducible Per2 gene. Induction of Per2 expression resulted in growth inhibition, cell cycle arrest, apoptosis, and loss of clonogenic ability. These results suggest that Per2 is a downstream C/EBPα-target gene involved in AML, and its disruption might be involved in initiation and/or progression of AML. (Blood. 2005; 106:2827-2836)
Hemolysis-associated priapism in sickle cell disease
Authors: Nolan Vikki G. , Wyszynski Diego F. , Farrer Lindsay A. , Steinberg Martin H. 
Published: June 2005

AbstractPriapism, although uncommon in the general population, is one of the many serious complications associated with sickle cell disease (SCD). Few studies have described the clinical and hematologic characteristics of individuals with priapism and SCD. Using data from the Cooperative Study for Sickle Cell Disease, we assembled 273 case subjects with priapism and 979 control subjects. Case subjects, compared with control subjects, had significantly lower levels of hemoglobin; higher levels of lactate dehydrogenase, bilirubin, and aspartate aminotransferase; and higher reticulocyte, white blood cell, and platelet counts. These findings suggest an association of priapism with increased hemolysis. Hemolysis decreases the availability of circulating nitric oxide, which plays an important role in erectile function.