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TU‐D‐I‐609‐02: What to Expect When CAD Is Implemented Clinically

Medical Physics 2005年第6期32卷 2093-2094页

作者： Nishikawa, R. Univ Chicago Chicago IL United States

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 detection 2. Understand some of the difficulties of measuring the clinical effectivenes

关键词： Cancer computer aided diagnosis Radiologists Biomedical modeling computer modeling science funding Mammography computer science and technology

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TH‐C‐J‐6B‐01: Guided Surgery Using Rapid Prototyping Patient Specific Guides

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Medical Physics 2005年第6期32卷 2158-2159页

作者： Rajon, D. Bova, F. Friedman, W. Garita, B. University of Florida Gainesville FL United States

Purpose: One of the basic tenets of Neurosurgical planning is the ability to generate an operative approach that minimizes the disruption of normal tissues while allowing the required access to target tissues. To aid the surgeon in his or her ability to appreciate the location of target tissues, as well as the relationship of the target to normal tissues, graphical workstation have been employed. The introduction of Image Guidance Systems (IGS) into OR has brought along a host of new computers, infrared camera systems and radio frequency transmitters and receivers, all of which pose restrictions on the placement and operation of the other equipment needed for the operative procedure. In order to provide the advantages of IGS while avoiding the problems associated with the commercial equipment we elected to investigate a mechanical alternative, one that did not require any of the above equipment to be present with the operating room. Method and Materials: Recently, a new generation of 3‐dimensional printers has been developed. These systems are capable of fabricating OR compatible objects within an hour of design. The goal of this project is to develop software that provides the surgeon with the ability to build a patient specific 3D model from a diagnostic image dataset and to then plan a surgical procedure. Utilizing the 3D patient specific model, the software designs a patient specific reference frame and fabricates the frame using rapid prototyping technology. This reference frame incorporate all necessary trajectories, including mechanical referencing to the patient, guidance for initial skin incision, trajectory alignment to the target tissues, as well as providing a mechanical platform for mounting other surgical tools. Results Conclusion: We have written and tested this new generation of software on phantom targets and are now engaged in an IRB surgical trial assessing the system's accuracy and precision. © 2005, American Association of Physicists in Medicine

关键词： Tissues computer software Medical imaging Trajectory models Tissue engineering Cameras computer systems Skin computer science and technology Infrared detectors

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TU‐B‐I‐618‐02: Converting the Radiology Department From Film‐Screen to Digital — Making the Transition

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Medical Physics 2005年第6期32卷 2076-2077页

作者： Shepard, S.J. U. T. M. D. Anderson Cancer Center Houston TX United States

In recent years, Picture Archiving and Communications Systems have begun to proliferate in the medical community. This is a result of technical advances that have occurred in two areas — advances in computer technology (such as storage density, processing speeds, network bandwidth, compression techniques, and so on), and the maturation of robust standards for communication and transmission of medical images and information (Standards like HL‐7, DICOM, and IHE). In parallel with these developments, the medical imaging equipment and information systems vendors have been developing robust software implementations and more advanced system architecture to take advantage of this emerging technology and these robust standards. As a result of this revolutionary change in the way we operate, it has become increasingly important that we in the Medical Physics community modify our approach to the type of support we bring to these operations accordingly. This presentation will focus on some of the issues the Medical Physicist is likely to face when supporting a clinical operation that is undergoing (or is about to undergo) a conversion from film‐screen base radiography to digitally acquired images. It will cover the educational needs of the Medical Physicist, radiologists and technical staff, how to use photostimulable phosphor imaging to introduce a radiology department to digital imaging, the importance of Modality Work List Management in the filmless radiology environment, selection of a DDR system for clinical use, weaning the referring clinicians off of film and what issues are important to achieving this, quality control programs for digital imaging systems, and finally those features of the radiology reading room environment that are important for soft‐copy interpretation. © 2005, American Association of Physicists in Medicine. All rights reserved.

关键词： Medical imaging Medical image quality computer science and technology Medical physicists Bioinformatics Emerging informatics technologies computer systems Information processing Information and communication theory Medical image processing

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SU‐FF‐I‐65: A Diagnostic X‐Ray Simulator for Out‐Patient‐Department Examinations

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Medical Physics 2005年第6期32卷 1918-1919页

作者： Chao, T. Liu, C. Lee, C. xu, X. Chang‐Gung University Kwei‐Shan Tao‐Yuan TW 259 Wen‐Hwa 1st Road Taiwan Rensselaer Polytechnic Inst. Troy NY United States

Purpose: To develop a diagnostic X‐ray image simulator for commonly used out‐patient‐department examinations including lower extremities, skull, abdomen, pelvis, chest, and spinal cord. This simulator can be used as a computer‐assistant‐teaching software for training technologists more familiar with the relationship between image quality and operation conditions. Method and Materials: A detailed simulation of a diagnostic X‐ray image requires four major inputs: operation conditions, X‐ray spectral and spatial distributions, a human model, and cross‐section corresponding to different materials. This study has collected commonly used operation conditions such as kVp, mAs, SSD for different OPD examinations. These conditions have been inputted to a Monte Carlo code, BEAMnrc, to build a virtual X‐ray machine for calculating X‐ray spectral and spatial distributions. After that, a high resolution voxelized human model, VIP‐Man constructed from segmented Visible Male Dataset, will be imaged with this virtual X‐ray machine. The cross‐sections of different materials are generated by PEGS4, a cross‐section preparation tool come with EGS4. Results: X‐ray spectra simulated using BEAMnrc is almost identical to those listed in literatures, or from a spectra simulator, XCOMP3;except there is about 30% underestimation in characteristic peaks. However, this underestimation will lead to less than 0.1% deviation in our simulation. Heel effects can be observed in our simulated images. The intensity response was calibrated to a real digital X‐ray machine, and point spread functions of this machine are measured to degrade our simulated images. Conclusion: We have developed this X‐ray image simulator which can benefit the training of technologists. This simulator can be further improved to serve as a platform for studying image quality parameters such as QDE or MTF after we adding more realistic model of image receptor. © 2005, American Association of Physicists in Medicine. All rights re

关键词： Spatial analysis Modulation transfer functions computer software Real functions computer science and technology Spectral properties

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SU‐FF‐T‐90: The Use of Bluetooth technology in Multiple Monitoring of Vital Signs ‐ ECG and Pulse

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Medical Physics 2005年第6期32卷 1970-1970页

作者： Cosma, V. Ciorba, D. Cosma, C. Babes‐Bolyai University Cluj‐Napoca Cluj Romania

Purpose: The aim of this work is to evaluate the strengths and demonstrate the benefit of using Bluetooth wireless technology in medical equipment, for close monitoring of multiple patients with heart problems (ECG and vital signs) in recuperatory stage. The main issue discussed and tested is whether Bluetooth technology is ready to be implemented and used to realize an environment were computers would assist the medical staff in offering solutions and real time response, based on the data received from patients, in critical situations. Method and Materials: Our preliminary work consists in a simulation soft (VC++) for monitoring two patients (ECG and pulse), with two Bluetooth equipped devices. Bluetooth is a rather new low‐cost radio technology which operates in the free, unlicensed 2.4 – 2.4835 GHz ISM (Industrial, Scientific, Medical) band, and is designed to unite or connect all different types of devices to effectively work as one. The soft created is a server‐client based program that interact through information messages interpreted as graphs and action instructions. Results: The server receives instantaneously the data sent by the patients and after a process of comparing, in which if the data for Pulse or ECG is higher or lower than some user‐specified values, it builds dynamic charts for the two patients. We assumed the following limits both for ECG and Pulse: lower=50 and upper=130. A counter holds the number of times these values were crossed (under/over), and at 5 or more the application is stopped, and pre‐defined messages will appear on the server and patient interfaces. Conclusion: The tests performed presented a very good response of the system — real time — thus giving us a very good reason to think that this technology could be used to perform hard tasks and intervene much more accurate than human personnel can. © 2005, American Association of Physicists in Medicine. All rights reserved.

关键词： computer science and technology computer simulation Interstellar medium Heart disease Biomedical equipment

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SU‐CC‐J‐6C‐08: Automated Beam Direction Selection for IMRT Based On Geometrical Concepts of Viewability and Orthogonality

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Medical Physics 2005年第6期32卷 1890-1890页

作者： Clark, V. Alaly, J. Zakarian, K. Deasy, J. Washington Univ. St Louis MO United States

Purpose: To develop a fast and reliable algorithm to automatically select beam angles for intensity‐modulated radiation therapy (IMRT) treatment planning. We hypothesized that such an algorithm could be developed based on purely geometrical concepts as a pre‐planning step. Method and Materials: We define any point in the target as viewable by a given beam if a ray from that beam, which passes through the point, does not intersect any critical structures (i.e., the point can be ‘viewed’ by that beam). The beam angle selection problem can then be generalized to the multi‐set cover problem, a difficult (NP‐hard) computer science problem. We also consider orthogonality, which captures beam non‐overlap outside the target. We hypothesize that increasing 3‐viewability (fraction of points viewable by at least 3 beams) and increasing orthogonality typically results in higher quality IMRT dose distributions. This was tested by comparing, for 30 random sets of 5 beam angles, the objective function based on 3‐viewability and orthogonality vs. the final objective function value output of a weighted quadratic IMRT optimization. Our beam angle selection algorithm extends a greedy set cover algorithm and aims to find a set of coplanar angles that will make a maximum fraction of target points at least k‐viewable while also maximizing orthogonality. Results: For an IMRT case where beam angle selection impacted IMRT objective function values, there was a strong correlation between the viewability‐orthogonality objective function value and the final objective function value of a weighted quadratic IMRT optimization (Spearman correlation coefficient 0.63 (p<0.0004)). Our proposed algorithm determines beam angles for a typical plan in 2–4 minutes on a 2 GHz PC. Conclusion: We conclude that the purely geometrical concepts of viewability and orthogonality can be used as a basis for automatically and efficiently selecting IMRT beam angles using the class of algorithms proposed. © 2005, Amer

关键词： Intensity modulated radiation therapy Angular correlation Dosimetry Radiation therapy Medical treatment planning computer science and technology

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MO‐B‐T‐6B‐01: Quality Assurance of Radiation Treatment Planning Systems: A Significant Challenge?

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Medical Physics 2005年第6期32卷 2051-2051页

作者： Van Dyk, J. London Regional Cancer Program London Health Sciences Centre London ON Canada

During the last decade there has been a technological revolution in radiation oncology. Enhanced use of imaging combined with computer‐controlled methods of dose delivery provides a capability of escalating tumor doses without increasing morbidity. A pivotal component of this modern technology is the computerized radiation treatment planning system (RTPS) which is used to develop optimal treatment techniques for individual patients. Modern RTPSs make increased use of patient images, possibly from various imaging modalities, enhanced 3‐D displays, more sophisticated dose calculation algorithms, more complex treatment plan evaluation tools, combined with the generation of images which can be used for treatment verification. In addition, the implementation of intensity modulated radiation therapy (IMRT) has added a further complexity to the RTPS and this is combined with automated optimization software which is essential if IMRT is going to be used to its best advantage. In recent years, various national and international organizations have developed reports that have made recommendations regarding the commissioning and quality assurance (QA) of RTPSs. In 1998, AAPM TG53 published guidelines for users and vendors on QA for radiation therapy planning. In 2000, the International Electrotechnical Commission (IEC) produced a report (IEC 62083) specifically on safety requirements for manufacturers of RTPSs. In 2004, both the International Atomic Energy Agency (IAEA) and the European Society of Therapeutic Radiation Oncology (ESTRO) published reports on commissioning and QA of RTPSs. Furthermore, the IAEA is presently in the process of developing a protocol for the acceptance testing of RTPSs. In 2005, the Netherlands Commission of Radiation Dosimetry also produced a report on QA of RTPSs. All of these reports indicate that a thorough commissioning of a modern 3‐D RTPS has become a daunting task. This refresher course will look at some of these reports and review issues asso

关键词： Semiconductor device fabrication Radiation treatment Medical imaging Dosimetry Quality assurance Cancer Intensity modulated radiation therapy Testing procedures Image enhancement computer science and technology

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TU‐D‐I‐609‐04: Effect of Reader Variability On Improvements in Breast Cancer Detection Rates

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Medical Physics 2005年第6期32卷 2094-2094页

作者： Jiang, Y. Miglioretti, D. Metz, C. Schmidt, R. University of Chicago Chicago IL United States Group Health Cooperative Seattle WA United States

Previous investigations have demonstrated variability among radiologists in the interpretation of screening mammograms. This presentation will discuss the extent of this variability and its effect on clinical trials that compare the conventional screening‐film mammography and new technologies such as full‐field digital mammography (FFDM) and computer‐aided detection (CADe). We will present data on breast cancer detection rates at the conventional screen‐film mammography of over 500 practicing community radiologists in the US. By postulating a large improvement in the cancer detection rate that would be achieved with a hypothetical new technology, we predicted the cancer detection rate that would be observed in a hypothetical clinical trial comparing the new technology and the conventional screen‐film mammography. Despite a large postulated improvement in the cancer detection rate, it is difficult for clinical trials to demonstrate this improvement. Variability among radiologists in the observed cancer detection rates is an important cause for this difficulty. Clinical trials need to include large samples of radiologists in addition to large samples of patients to achieve sufficient statistical power to detect an improvement in the breast cancer detection rate in screening mammography. FFDM and CADe clinical trials, many of which appear to lack statistical power, will be discussed. Educational Objectives: 1. To understand the sources and extent of variability in radiologists' breast cancer detection rates in screening mammography. 2. To understand the impact of reader variability on clinical trials that compare imaging technologies in screening mammography. 3. To understand the need to sample a large number of radiologists in addition to sampling a large number of patients to demonstrate an improvement in breast cancer detection rate in screening mammography. 4. Financial Disclosure: C Metz and R Schmidt are shareholders of R2 technology, Inc. © 2005, American Associ

关键词： Cancer Mammography Radiologists computer aided diagnosis Digital mammography Medical imaging computer science and technology Ultrasonography

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SU‐FF‐E‐02: Modern Digital Seminar/Teaching/ Conference Room

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Medical Physics 2005年第6期32卷 1903-1903页

作者： Venkataramanan, N. Ortiz, Orlando Winthrop Univ Hospital Syosset NY United States

Purpose: Digital Teaching/Seminar/Conference Room for the modern era. Method and Materials: Learn about and become familiar with the resources available to set up a digital teaching/seminar/conference room Results: 1. Assess the technologic innovations in hardware, software and network design and the impact to the conference room. 2. Understand ways to optimize your images for visual display with respect to luminance, gray scale imaging, contrast and distortion. 3. Review the technologies available for the storage, projection, and display of a presentation. Conclusion: Reviewed how the teaching/seminar / conference room has evolved in parallel with the changes from an analog to a digital environment. © 2005, American Association of Physicists in Medicine. All rights reserved.

关键词： Environmental impacts computer science and technology

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WE‐C‐T‐6E‐05: NEXGEN Restorative Health Care Thru Synthetic Biology and Nanoscience

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Medical Physics 2005年第6期32卷 2130-2130页

作者： Montemagno, C. Roy and Carol Doumani Professor and Chair Department of Bioengineering University of California Los Angeles CA United States

Recent advances in our ability to manipulate matter at the scale of individual molecules have created an incredible level of excitement in both the scientific community and the general population. The excitement over this new capability, commonly labeled nanotechnology, is vested in the expectation of the development of new materials and systems that offer unparalleled functionality. Materials that autonomously adapt their shape and physical properties in response to the their surroundings, computers that instead of operating by switching the flow of electrons, manipulate information through the management of the ethereal world of quantum states and, molecular sized machines that actively repair damage to our bodies and function as molecular scale prosthetics are all expectations of nanotechnology. While the question of whether or not this vision is truly achievable is still open, the truth is that much of the expectations for nanotechnology are already realized in living systems. Living systems however, are more than a product of matter manipulation at the molecular scale;the richness of functionality associated with living systems is a direct product of the information generated from both the interactions between molecules and the overall supra‐molecular structure of the system. In essence living systems are “living” because of the fusion of nanotechnology and informatics. Living systems result from the precision assembly of matter with prescribed modalities for the transport and transduction of information among supra‐molecular clusters. Recent advances in surgical and diagnostic tools emanating from nanotechnology will be presented in the context of Integrative technology. Integrative technology is the intersection of the precision assembly of matter, nanotechnology, coupled with the functional building blocks of nature, biotechnology, fused by the network flow of spatiotemporal information, informatics. The power of Integrative technology is illuminated through

关键词： Nanotechnology Informatics Materials properties computer science and technology Information integration Biotechnology Quantum information Molecular electronic properties Signal generators Quantum computing

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