bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐GG‐T‐477: Influence of Pitch and Jaw Width On Helical Tomotherapy Head and Neck Treatment Planning
Authors: Moldovan M , Lee T , Chu C , Hogstrom K , Fields R , Gibbons J 
Published: July 2008

Purpose: To investigate the influence of pitch and jaw width selection on helical tomotherapy treatment plans for head and neck. Method and Materials: Helical tomotherapy plans using a combination of pitch and jaw width settings were developed for three patients previously treated for head and neck cancer. Three jaw widths (5, 2.5 and 1 cm) and six pitches (0.86, 0.7, 0.43, 0.34, 0.287 and 0.215) were used with a (maximum) modulation factor setting of 4. The 18 plans per patient were generated using an identical optimization procedure (e.g., number of iterations, objective weights and penalties, etc.), based on recommendations from TomoTherapy. The plans were compared using isodose plots, dose volume histograms, dose homogeneity indices, conformity indices, radiobiological models, and treatment times. Results: Smaller pitches and jaw widths showed better target dose homogeneity and sparing of normal tissue, as expected. The conformity index had a maximum for pitches between 0.287 and 0.43. The tumor control probabilities were greater than 99% for the 2.5‐ and 1‐cm jaw widths for all pitches except 0.86. The treatment time increased inversely proportional to the jaw width. Conclusion: Our study indicates that the smaller jaw widths (2.5 and 1 cm) and pitches near the range of 0.3–0.4 produce better plans for helical tomotherapy head and neck treatment. However, because of the large increase in treatment time with only slight improvement in sparing of the critical structures for the 1‐cm jaw width, the 2.5‐cm jaw width, currently used in our clinic, remains our preference.Supported in part by a research agreement with TomoTherapy, Inc.
SU‐GG‐T‐485: Comparison of Rush University In‐House Dose Optimizer and Nucletron IPSA
Authors: Liao Y , Kirk M , Turian J , Bernard D , Zusag T , Chu J 
Published: July 2008

Purpose: We quantitatively compared the Rush University In‐house Optimizer (RUIDO) with the Inverse Planning with Simulated Annealing (IPSA) used in Nucletron Plato Treatment Planning System. Method and Materials: RUIDO uses Adaptive Simulated Annealing (ASA) optimization algorithm, which is capable of optimizing a plan based on either physical dose, EUD, or TCP/NTCP. In this study, only physical dose optimization is compared. Three Syed implant HDR cases were planned using both RUIDO and IPSA. For each case, the number and positions of the catheters remain the same, and dwell time for each source position is optimized. Based on the Dose‐Volume‐Histogram (DVH) from both optimized plans, detailed comparison of coverage (CI), homogeneity (HI), and overdose (OI), etc. were performed. The source strengths in RUIDO plans were scaled to provide similar CI as the corresponding IPSA plan during plan comparison. Results: For all three cases, the normalized RUIDO plans show similar CI (within 0.1%) as the IPSA plans. In two cases, RUIDO plans appear better with higher HI (9% and 16%) and lower OI (16% and 45%). In the third case, two plans were tied, as RUIDO plan shows preferable HI (13% higher) but less preferable OI (12% lower). In addition, for all three cases, mean dose in both plans agree within 7%. It takes 10–15 seconds for IPSA to optimize the plan once. However, it might take several more trials for the user to obtain the optimal set of parameters depending on the user's experience. RUIDO plan, on the other hand, can generate the optimized plan within minutes (1–16 minutes), but it only takes one trial to do this hence needs possible shorter overall planning time. Conclusion: RUIDO is able to provide equivalent plan with possible shorter overall planning time compared with IPSA and is less user‐dependent.Partially funded by Varian Medical Systems.
SU‐HH‐AUD C‐08: Spatial Weighted Mutual Information for Image Registration in Image Guided Radiation Therapy
Authors: Park SB , Rhee FC , Monroe JI , Sohn JW 
Published: July 2008

Purpose: To develop a robust registration algorithm for medical images, emphasizing the registration of plan images with cone beam computed tomography (CBCT) images for IGRT. Our Spatial Weighted Mutual Information (SWMI) technique assigns greater importance to user‐selected volume, allowing medically ‘important’ areas to dominate the registration process. Method and Materials: Mutual Information (MI) is the most popular measure of image registration due to its robustness and multi‐modal capability. However, MI does have difficulty where organ deformation is present. We reformulated the MI algorithm by incorporating an adaptable weight function to user selected spatial locations. Since MI is defined in probabilistic space, we proposed a spatial‐weighted joint probability, and composed a Spatial Weighted Mutual Information measure. Our image registration software and Graphical User Interface (GUI) was programmed in C++ to import DICOM images and DICOM‐RT information, and to perform image registration. For this study, we used Gaussian‐shaped spatial weights applied to a user‐defined volume. Our software allows a user to adjust the Gaussian parameters via the GUI. Convergence and robustness of our registration method was first tested with a head‐and‐neck plan and seven CBCT image sets. Then, a prostate plan with nine CBCT image sets was analyzed. Speed of convergence was tested by arbitrarily miss‐aligning two image sets ±15mm over 41 trials. We also applied our algorithm to fuse CT and MRI image sets. Results and Discussion: Image registration using our measure converges 10% faster than using Mutual Information. Our study showed image registration using a uniform weight over an entire volume lead to compromised target coverage. SWMI showed better alignment near target areas and neighboring critical organs even with organ deformation. Our method worked well in fusing MRI to CT images as well.(This work is partly supported by Susan G. Komen Breast Foundation Grant: BTCR126506).
MO‐SAMS‐AUD B‐01: Stereotactic Body Radiation Therapy (SBRT) I: Clinical and Radiobiological Considerations
Authors: Kavanagh B , Chang E , Chang Eric Lin 
Published: July 2008

Stereotactic Body Radiation Therapy (SBRT) has emerged as an important form of cancer therapy with broad application across a spectrum of tumor types in the primary and metastatic settings. The capability of safely administering a very high dose of therapeutic radiation to discrete extracranial tumor sites has raised new questions about the radiobiology of high dose per fraction treatment. Accumulating clinical experiences are yielding new insights into practical aspects of tumor and normal tissue responses to high dose per fraction treatment.The current practice of SBRT has evolved to some extent from knowledge gained from principles learned from the practice of cranial stereotactic radiosurgery (SRS), and this presentation will begin with discussion of the use of SBRT for sites where the extracranial nervous system (spinal cord, cauda equina) is the major dose‐limiting structure. Some recent preclinical studies of spinal cord tolerance to high dose therapy will be presented, as well as the results of recent clinical trials involving spine SBRT from various centers. Next, the discussion will focus on other major extracranial sites where SBRT has been applied, with emphasis on SBRT for tumors in the liver and lung in particular, again with inclusion of theoretical and preclinical studies as well as reported clinical outcomes.Educational Objectives:1. Review and understand the major issues related to the use SBRT for tumors in the spine or paraspinous region, including key clinical observations.2. Review and understand the common clinically observed normal tissue responses to SBRT and the inferences to be drawn regarding the practical radiobiology of high dose per fraction therapy.3. Explore and highlight the major issues related to clinical application of SBRT for tumors in the lung and liver, including key clinical observations.
MO‐SAMS‐AUD B‐02: Stereotactic Body Radiation Therapy (SBRT) II: Physics and Dosimetry Considerations
Authors: Benedict S , Yenice K 
Published: July 2008

SBRT of well defined extracranial targets in various anatomical locations demands special treatment planning considerations due to limitations of dose calculation algorithms in heterogeneous medium and small field dosimetry coupled with tumor/organ motion and multiple radiobiological constraints. Unlike conventional intracranial radiosurgery, SBRT treatment planning and delivery are confounded by reduced 3D physical space for beam placement due to possibility of treatment machine and patient collision as well as a multiplicity of surrounding serial and parallel architecture organs. Currently advanced treatment planning techniques with radiobiological considerations and precise image‐guided treatment delivery methods are practiced for SBRT delivery to a wide variety of tumor types.The physics and dosimetry presentation will include an overview of the available technology for SBRT with an emphasis on image guidance, Quality Assurance, and clinical implementation of SBRT. The presentation will also include site specific treatment planning techniques with considerations to accuracy of dose calculation algorithms, radiobiological issues, and physics reporting strategies.Educational Objectives:1. Understand the issues related to the clinical implementation and technical aspects of SBRT techniques and technology and become familiar with the preliminary reporting of AAPM Task Group 101.2. Understand the importance of QA procedures and guidelines and reporting requirements for SBRT.3. Understand the practical aspects of SBRT treatment planning for paraspinal, lung, liver, and abdominal tumors and recognize the critical issues related to each site.4. Understand the importance and limitations of dose calculation algorithms and heterogeneity correction methods for SBRT in various anatomical sites.
MO‐D‐AUD A‐01: Summarizing Our Knowledge of Normal Tissue Tolerances: The Progress and Future Directions of QUANTEC
Authors: Jackson A 
Published: July 2008

AAPM and ASTRO are jointly funding an effort, called QUANTEC (QUAntitative Normal TissuE models in the Clinic), which aims to summarize our knowledge of dose volume dependencies of the normal tissue complications of external beam radiotherapy, and where possible, give quantitative guidance for clinical treatment planning and optimization. Following the initial QUANTEC meeting in Madison in October 2007, attended by approximately 75 physicists, MDs and bio‐statisticians, an upcoming special issue of the Red Journal is in preparation, which will include articles on complications in some 18 normal organs. For each of these organs, extensive literature reviews were undertaken, and clinically significant endpoints identified. Where possible, results were synthesized and compared, guided by the quality and levels of evidence of the studies. Criteria included prospective or retrospective nature, statistical power, presence and reliability of quantitative data on dose‐volume effects. Other clinical factors influencing complications were assessed, such as the influence of chemotherapy, fraction size and pre‐existing medical conditions. Special emphasis was placed on attempting to provide quantitative guidelines for clinical treatment planning. This talk will convey the mission, and give selected examples of the achievements of QUANTEC. It will outline the current state of our knowledge, and highlight areas where opportunities exist to improve our understanding.Educational Objectives:1. To understand the current state of knowledge of dose volume dependencies of complication probabilities.2. To understand the criteria and methods used by QUANTEC in selecting and summarizing this knowledge.3. To understand the shortcomings of the clinical data as it currently exists.4. To understand the possible strategies for overcoming these shortcomings.
MO‐E‐342‐02: Quantitation in Nuclear Medicine
Authors: King M 
Published: July 2008

The quantification of function and activity plays an important role clinically in nuclear medicine. Examples include the analysis of tracer kinetics to quantify dynamic function, the determination of the fraction of the cardiac blood pool ejected during contraction, the comparison of regional localization of uptake within the heart to that of a database to facilitate the recognition of perfusion defects in cardiac imaging, and the localization of F‐18 labeled FDG in potential lesions. Despite the present clinical utility of quantification a number of factors limit current methods. The successful addressing of these factors would expand the clinical utility of quantification and are the subject current and future investigations.This lecture will provide an introduction to the application of quantification within nuclear medicine. It will point out some current deficiencies, and potential research directions aimed at over coming them.Educational Objectives:1. Understand the various types of quantification employed in nuclear medicine.2. Recognize some of the limitations to robust application of quantification clinically.3. Appreciate some of the proposed methods to overcome these limitations.
TU‐C‐350‐04: The Rationale and Realities of the CARE Bill
Authors: Vanek K 
Published: July 2008

The Consistency, Accuracy, Responsibility, and Excellence in Medical Imaging and Radiation Therapy (CARE bill) was first introduced in the 106th Congress on September 26, 2000. Since that time, it has been introduced in all subsequent Congressional sessions including the current 110th Congress. The bills are now co‐sponsored by 122 US Representatives and 22 US Senators. The CARE bill directs the Secretary of Health and Human Services to establish education and credentialing standards for all persons performing medical imaging, planning, and delivering radiation therapy. Each individual State will be responsible for developing procedures to insure compliance with the federal regulations. The origin, history, and importance of the CARE bills will be discussed as well as AAPM's involvement with the Alliance in this legislative effort. Political realities that have been encountered during this process will be reviewed and suggested actions that members can take to help the CARE bill become law will be presented. Additional effort by the AAPM, the Alliance, and individual members after the CARE bill passage will be also be identified and discussed.Educational Objectives:1. Understand basic differences between certification, credentialing, registration, and licensure.2. Understand the CARE bill and its importance to medical physicists.3. Understand the current status of the CARE bill and actions that can be taken to help passage by Congress.4. Understand the subsequent actions by members that will be required on a State government level.
TU‐D‐342‐01: Advances in Breast Imaging
Authors: Whitman G 
Published: July 2008

Over the last decade, there have been tremendous advances in breast imaging. As many facilities make the transition from film screen to digital mammography, it is appropriate to examine the accomplishments of the past and to acknowledge current technological limitations. In addition, we should carefully study evolving technologies in breast imaging with the goal of developing highly sensitive and highly specific techniques. This presentation will examine recent progress in digital mammography, including contrast‐enhanced imaging, tomosynthesis, and breast CT, from a breast imager's perspective.Randomized clinical trials and meta‐analyses have shown that screening mammography results in a decrease in breast cancer mortality. Although mammography is efficacious in most women, we know that mammography is not a perfect test, epecially in women with radiographically dense breasts. Furthermore, false positive and false negative mammograms are difficult to eliminate. As digital mammography replaces film screen mammography in many practice settings, cancer detection rates may rise slightly and call back rates may decrease slightly.Overlapping densities and areas of dense tissue often make interpretation of film screen mammograms difficult. Overlapping parenchyma and dense tissue hinder digital mammography less than film screen mammography, but these overlying structures are not eliminated with digital mammography. Major efforts have been made in digital tomosynthesis and breast CT in order to advance beyond projection imaging. Tomosynthesis involves the acquisition of tomographic images in the digital mammography unit, while breast CT is based on a volumetric acquisition with the patient positioned prone in a machine that is similar to a unit used for stereotactic biopsies.Conventional digital mammography, digital tomosynthesis, and breast CT may be combined with the injection of iodinated contrast material in order to visualize tumor vascularity and increase the conspicuity of breast tumors. These techniques may also be used to monitor response to neoadjuvant chemotherapy.Over the next decade, tomosynthesis and breast CT will transition from research applications to clinical realities. Further studies are needed in order to determine how to use these emerging tools in an effective, efficacious manner.Educational Objectives:1. To review advances in breast imaging over the last decade.2. To understand the strengths and weaknesses of film screen and digital mammography.3. To appreciate the potential roles of digital tomosynthesis and breast CT.4. To understand the application of iodinated contrast material in digital mammography, tomosynthesis, and breast CT.
TU‐D‐342‐03: Contrast‐Enhanced Breast Imaging
Authors: Maidment A 
Published: July 2008

For almost 70 years mammography has given insight into breast morphology, allowing cancer detection based on the gross impact of the disease upon body. The advent of tomographic techniques has allowed visualization of morphologic perturbations at a much smaller scale using various techniques including digital breast tomosynthesis (DBT), computed tomography (CT), ultrasound, and magnetic resonance imaging (MRI).An alternative strategy to improve early detection is to search for functional changes. In 2007, the American Cancer Society revised their breast cancer screening recommendations. Annual screening by mammography is still recommended for women at low‐to‐medium risk for breast cancer; however, women at high risk for breast cancer are now recommended to have annual mammography and MRI. This recommendation is supported by studies which show that MRI is capable of demonstrating mammographically‐occult breast cancer both in both screening and diagnostic populations.Contrast‐enhanced (CE) radiographic methods, including CE‐mammography, CE‐DBT and CE‐CT, have the potential to rival breast MRI as a sensitive method for diagnosis and screening of breast cancer. In a pilot study of CE‐DBT conducted at the University of Pennsylvania, suspicious enhancing lesions were demonstrated in 14 of 15 cases of breast cancer. The pre‐contrast tomosynthesis images demonstrated lesion morphology and border characteristics in greater detail than digital mammography, while the subtracted contrast‐enhanced tomosynthesis images demonstrated the vascular characteristics of the breast lesions in a manner consistent with breast MRI.Further advances in CE imaging will be predicated upon shifting our attention from imaging perfusion to imaging specific molecular/cellular events. Research is ongoing in the discovery of specific biological prognostic factors, the development of appropriate imaging technologies and imaging agents, and the adaptation of these technologies to image‐guidance and monitoring of therapeutic interventions.Educational Objectives:1. Review the development of contrast‐enhanced breast imaging.2. Evaluate the results of the existing contrast‐enhanced clinical trials.3. Examine the clinical roles for contrast‐enhanced imaging.
TU‐EE‐A3‐01: Breathing‐Motion Induced Tomotherapy Dose Delivery Errors in the Presence of Beam Modulation
Authors: Chaudhari S , Low D , Rangaraj D , Kintzel E , Goddu S 
Published: July 2008

Purpose: To determine breathing‐motion induced Tomotherapy dose delivery errors in the presence of beam modulation. Method and Materials: Previous studies have shown that dose delivery errors are possible due to breathing motion. While these studies have systematically investigated the roles of field size, couch velocity, and breathing motion magnitude on the dose errors, they have neglected the role of intensity modulation. This study used measured breathing patterns and clinically realistic delivery parameters to simulate the breathing‐motion induced errors. Modulation was included by varying the simulated delivered dose on two timescales; the short timescale simulating the 51 angular subsets that subdivide the delivered fluence patterns. A step function was used that varied the leaves open and close time every 0.4 seconds, or every 7.0°, simulating a modulation factor of 2.0. Modulation was also conducted on a longer timescale corresponding to four beam intensity directions (two of high dose and two of low dose). The earlier studies using 52 patients' breathing patterns were repeated with the addition of fluence modulation. Results: The impact of breathing motion on Tomotherapy delivery results in delivery errors of greater than 10%, even for relatively small breathing motions. This is due to the subtle variation in the breathing patterns, including changes in breathing waveform and drifting. The addition of fluence modulation varied the delivered dose patterns slightly, but the magnitude of dose delivery errors was unchanged. Conclusion: These results indicate that previous simulations indicating the challenges of using Tomotherapy dose delivery due to breathing motion are valid in the presence of beam modulation. Treatment planners should take care when planning treatments for mobile tumors.This work supported in part by Tomotherapy.
TU‐E‐350‐04: The Practice of Clinical Therapy Medical Physics
Authors: Hevezi J 
Published: July 2008

Clinical Therapy Physics is the real “practice” of Medical Physics. Therapy Medical Physics is reimbursed explicitly and implicitly as having direct contribution to specific patient care — the only Medical Physics sub‐field with this advantage. Whether it is in establishing External Beam, IMRT, SRS or SBRT programs with IGRT or providing Brachytherapy (HDR & LDR) programs for cancer therapy, the Clinical Therapy Medical Physicist works in partnership with the Radiation Oncologist to provide quality services in cancer care. Supervision of dosimetrists and therapists, the other members of the radiation oncology team is an important part played by us.Dr. Hevezi was Director of Medical Physics at the Cancer Therapy & Research Center for 15 years and built an important clinical therapy physics program there. A broad range of clinical services there included not only the above mentioned procedures, but procedures like Total Body Photon Therapy, COMS Eye Plaque therapy, and others. He currently serves as Lead CyberKnife Physicist with the South Texas RadioSurgery Associantion in San Antonio and directs Medical Physics graduate students in the University of Texas Health Science Center at San Antonio. Dr. Hevezi has been recently elected to the Board of Chancellors of the American College of Radiology where he serves as Chair of the Medical Physics Commission. He is current Chair of AAPM's Professional Economics Committee and most recent clinical interest is in developing the CyberKnife SBRT treatment modality for cancer therapy.