bluuebunny/crossref_metadata_2025_split huggingface dataset:
MO‐D‐BRD‐04: Innovations in Hadron Beam Generation with Plasmas
Authors: Capelli M 
Published: April 2010

Proton radiotherapy for cancer is growing in the US and around the world. This growth is due to the physical advantages of the improved ability to deposit most of the radiation dose in the tumor, as opposed to x‐rays where most of the dose is deposited in normal tissues. In the US there are currently five proton therapy centers treating patients and over 2,300 x‐ray based linear accelerator facilities. Limiting the widespread application of proton radiotherapy to the general cancer patient community is the capital, building and operating costs associated with proton radiotherapy that exceed $ 100 million per site, a substantial cost differential with x‐ray based facilities. A compelling approach is to combine the physical advantages of proton therapy into a smaller, cheaper, gantry mountable system that can be widely disseminated. This requires a radical breakthrough in accelerator technology, however, as the size and mass of such an accelerator would have to be at least an order of magnitude less than those of conventional cyclotrons and synchrotrons. The Plasma Physics Laboratory at Stanford has developed a novel particle accelerator that is based on a newly‐understood second mode of operation in co‐axial plasma accelerators. By processing a plasma instead of a pure ion gas, the proposed accelerator is fundamentally different from electrostatic accelerators, resulting in two important advantages. First, a plasma gas contains electrons and positive ions, making it macroscopically neutral. As a result, it can tolerate high ion densities in a very compact device. Second, a plasma can conduct very high currents and self‐induce strong magnetic fields. This can be used to accelerate the plasma electromagnetically via the Lorentz force. The particle energy then becomes a function of the current to mass flow ratio rather than of the applied voltage. Eliminating the need for applying high voltages enables the generation of bursts of extremely energetic particles from a comparatively simple and inexpensive device. The recent identification and stabilization of a second mode of operation in coaxial plasma accelerators makes the advantages of plasma‐based approaches accessible to proton radiotherapy. The distinct features of the proposed plasma‐based accelerator may also result in attractive advantages when compared to alternative compact accelerator concepts that are currently under development.This lecture will provide an overview of the differences between plasma and pure ion acceleration, as well as some of the limitations that have historically limited plasma accelerators to low beam energy applications. It will then summarize the advantages of operating in the second mode and describe the challenges that have to be overcome to scale and develop the existing proof of concept prototype into a viable therapy machine.
MO‐D‐210A‐01: Photon Counting Detectors for Mammography
Authors: Danielsson M 
Published: April 2010

Mammography is currently one of the most common x‐ray imaging examinations. More than 100 million women worldwide are screened every year and early detection of breast cancer through mammography has proven to be a key to significantly reduced mortality. The requirement on spatial resolution as well as contrast resolution is very high in order to detect and diagnose the cancer. Moreover, because of the large number of women going through this procedure and the fact that more than 99 % are healthy, it also becomes very important to minimize the radiation dose.Photon counting may be one way to meet the demands and mammography is the first modality in x‐ray imaging to implement photon counting detectors. FDA approval is still pending but they are currently in routine clinical use in more than 15 countries. The photon counting enables a discrimination of all electronic noise and a more optimum use of the information in each x‐ray. The absence of electronic noise is particularly important in low dose applications, in for example tomosynthesis a number of exposures from different angles are required and since the dose in each projection is just a fraction of the total dose for a mammogram the sensitivity to electronic noise will increase.Using the spectral information for each x‐ray it is in principle possible to deduce the elemental composition of an object in the breast. This could for example be used to enhance microcalcifications relative to soft tissue and differentiate water from fat in cysts. Recently contrast mammography has attracted significant attention. In this application Iodine is used as a contrast media to visualize the vascular structure. As in breast MRI the cancer stand out because of the leaky vessels resulting from its angiogenesis. A photon counting detector gives a unique opportunity to image the Iodine through spectral imaging by adjusting one of the thresholds to its K‐edge.Challenges for photon counting in mammography are high rates of x‐rays, both to generate the required flux at the source and to handle the rates at the detector without pile‐up. Even more difficult to handle are the charge sharing between detector pixels which, if not corrected for, will compromise the energy information.The current status of photon counting detectors in mammography will be described together with strategies to overcome the pit‐falls. Also future possibilities with spectral imaging in mammography will be investigated and examples from ongoing clinical trials will be given.Learning Objectives:1. Status of photon counting detectors in mammography2. Pit‐falls and opportunities with photon counting detectors for mammography3. Future applications based on spectral detectors for mammography
MO‐D‐210A‐03: Energy‐Sensitive, Photon‐Counting Computed Tomography: Opportunities and Technological Challenges
Authors: Roessl E , Brendel B , Martens G , Proksa R , Schmidt F , Thran A , Schlomka J 
Published: April 2010

Recent advances in the development of direct‐conversion, energy‐sensitive x‐ray detectors stimulate research in the domain of pre‐clinical and clinical photon‐counting x‐ray computed tomography (CT). The ability to quantify the energy of individual X‐ray photons allows for novel approaches to improve the soft tissue differentiation, material decomposition and labeling techniques, the suppression of beam‐hardening artifacts as well as the potential reduction of radiation dose. Moreover, spectral data acquisition enables the selective and quantitative imaging of certain contrast media on top of the conventional anatomy, by tuning an energy threshold in the detector system to the K‐edge discontinuity of the contrast generating element in the agent.The present lecture will provide an overview of both, the opportunities and the technological challenges arising in the context of clinical, energy‐resolved, photon‐counting CT. Some examples of potential future applications will be given together with the most challenging technical difficulties encountered in the use of photon counting detectors in CT. The problem of counting photons at the high flux conditions of clinical CT will be discussed as well as the degradation of energy resolution by effects like pulse‐pileup or charge sharing.All authors are employees of Philips Research.Learning Objectives:1. To understand the physical basics of photon counting detectors and the implications on their use in x‐ray computed tomography2. To learn about a possible future application of energy‐sensitive CT in connection with the identification and quantification of contrast‐agents by means of the K‐edge discontinuity in the attenuation.3. To obtain an overview of the technological challenges to be overcome in order to realize photon‐counting CT in clinical practice.
MO‐D‐213A‐02: Practical Aspects of Nuclear Medicine Accreditation
Authors: Harkness B 
Published: April 2010

This lecture will present a review of the specific aspects and requirements of the nuclear medicine accreditation process. Particular emphasis will be placed on the process for SPECT cameras. The specifics of the phantoms, acquisition procedures, and the review of submitted data will be presented. Examples will be given for specific cameras. Upon completion of the course participants will be able to describe:1. The characteristics of the required ACR phantom for SPECT.2. The acquisition procedures used for accreditation in nuclear medicine.3. The image characteristics evaluated by the ACR phantom reviewers.
MO‐EE‐A1‐06: Performance of MPC‐Based Adaptive Radiotherapy Optimization
Authors: Jee K , Kashani R , McShan D , Fraass B 
Published: April 2010

Purpose: An adaptive re‐planning framework was used to account for tissue deformation during RT treatment courses. The framework is based on a multivariate control concept called model predictive control (MPC). A variety of control rules and optimization schemes were investigated using a prioritization‐based optimization method. Performance of the MPC control was evaluated with conventional evaluation metrics such as DVH, coverage, and homogeneity as well as model‐based plan evaluation metrics. Method and Materials: The Head/Neck IMRT treatment process was simulated using mid‐course CT scans, tracking treatment doses to tissues at the voxel level. Off‐line adaptation was performed with the changing patient model, updating the state of the process along with the dose‐to‐date information. Constrained optimizations were performed for re‐planning as well as for pre‐treatment planning. Multivariate control schemes including maximum constraint violation were utilized for re‐planning. Results: With the adaptation of the treatment plan to the patient‐specific anatomical changes, the predicted outputs could be efficiently controlled improving the robustness to those changes. Although the results show that the general trend in the predicted outputs follow the tissue volume changes, the clinical decision to re‐plan should be made by assessing the total predicted treatment output expectations. For cases investigated, a limited number (3∼4) of re‐plans were sufficient to control high priority outputs while the use of a tighter tolerance increased the number of re‐plans. Re‐plans were triggered mostly by the target coverage criteria. The studied course simulations indicate that significant changes are shown early in treatment. Therefore, frequent updates of the patient models may be necessary and critical to plan adaptation. Conclusion: The proposed multivariate control framework provided an intuitive method of articulating clinicians' decisions and priorities for re‐planning. In addition, the use of prioritization in re‐optimization may allow more efficient re‐planning which requires fewer planning resources.Supported in part by CA‐P01‐CA59827
MO‐E‐BRC‐01: Applying Single Molecule Real Time DNA Sequencing
Authors: Turner S 
Published: April 2010

SMRT (single molecule real time) DNA sequencing is a novel, high throughput method for sequencing DNA. It harnesses the intrinsic power of DNA polymerase enzymes as sequencing engines by eavesdropping on template‐directed synthesis in real‐time. Two critical technology components enable this process: The first is phospholinked nucleotides where, in contrast to other sequencing approaches, the fluorescent label is attached to the terminal phosphate rather than the base. The enzyme cleaves away the fluorophore as part of the incorporation process, leaving behind completely natural double‐stranded DNA. The second critical component is zero‐mode waveguide (ZMW) observation confinement technology that allows single‐molecule detection at concentrations of labeled analogs relevant to the enzyme. Through the combination of these innovations, our technology allows the speed, processivity, efficiency and fidelity of the enzyme to be exploited. We show application of this technology to shotgun sequencing of human and bacterial DNA resulting in high consensus accuracy and unprecedented readlength. Because with Phospholink nucleotides the polymerase reverts completely to the initial state after each base sequenced the accuracy profile as a function of position within a read is flat. We will present a novel sample prep concept based on DNA hairpin ligation to double‐stranded DNA that facilitates whole genome shotgun sequencing directly from genomic DNA with near‐Poisson limited coverage uniformity and practically no GC bias. This sample prep will be demonstrated to enable consensus sequencing based on data extracted from just one molecule, allowing high accuracy sequencing at the molecular limit and without amplification.Objectives• The attendee should be able to distinguish 2 technologies enabling SMRT DNA sequencing and characteristics of each.• They should be able to define what SMRT DNA sequencing is and how it differs from other sequencing technologies.• Attendees should be able to explain how high accuracy without amplification is achieved through sample prep — ie, what methods• Attendees will have learned about a unique sample prep process involving DNA hairpin ligation and double‐stranded DNA.
MO‐E‐BRC‐02: Challenges for Next‐Generation Accelerators
Authors: Lykken J 
Published: April 2010

Particle accelerators, once the exclusive playthings of high‐energy physicists, have become an essential technology for modern medicine, materials science, and molecular biology. The world's 7000 operating medical linacs have already enabled treatment of 30,000,000 patients, and new developments such as advanced proton therapies imply a growing demand for accelerators in the decades ahead.To serve the broadest possible patient population worldwide, medical accelerators need to become smaller, cheaper, and easier to operate. At first glance these needs appear orthogonal to those of particle physics, where the push has always been for larger more complex accelerators capable of reaching ever‐higher energies. However particle physicists have realized for some time that the 27 kilometer Large Hadron Collider, beginning operation this year, represents the last hurrah of conventional accelerator technology. The future lies with fundamentally new approaches that promise much stronger accelerating gradients. The same breakthroughs needed to make large high‐energy accelerators affordable will also make medical linacs smaller and cheaper.Fermilab and other national laboratories have taken the lead in developing new accelerator technologies with revolutionary potential. These include superconducting accelerating cavities, plasma wakefields, and laser acceleration. This lecture will provide a non‐technical overview of the prospects for next‐generation accelerators.Learning Objectives:1. Understand the increasing importance of particle accelerators across many disciplines.2. Understand the needs driving research into new accelerator technologies.3. Gain a working idea of the most promising avenues for next‐generation accelerators.
MO‐FF‐A3‐03: Quantitative Assessment of Automatic Anatomy Segmentation of 4D CT Images Using a Deformable Image Registration Algorithm
Authors: Dogan N , Sleeman W , Yan C , Fatyga M , Wu J , Christensen G , Hugo G , Weiss E , Williamson J 
Published: April 2010

Purpose: Quantify the accuracy of Small Deformation Inverse Consistent Linear Elastic (SICLE) deformable image registration to auto‐segment contours on 4D thoracic CT images. Method and Materials: A process of automatic contouring based on SICLE deformable image registration of respiratory CT phases from 4DCT scans was integrated into our image‐guided‐radiotherapy‐computing‐framework. The gross tumor volumes (GTVs), right and left lungs, cord and esophagus were manually‐drawn by the same physician for all ten respiratory phases. Registrations were performed using three intensity windows: 0–900 (lung only), 900–1300 (remaining tissue excluding lung) and 0–1300 (whole image). For each respiratory phase, the differences between the manually‐drawn and deformably‐mapped contours for each phase were quantified using fractional volume differences (FVDiff), differences in center of mass coordinates (COMdiff) and volume overlap index (VOI) and 3D maps of perpendicular distance between manually‐drawn and deformably‐mapped boundaries. The results were also compared against the previously‐implemented viscous fluid‐based registration. Results: The VOI for GTV and heart varied from 0.85 to 0.90, from 0.9 to 0.97, respectively. As expected, the smallest FVDiff were found be for the lungs (<0.027). The SICLE (0–900) and viscous fluid methods yielded similar GTV COM in superior‐inferior direction. COMdiff were largest for the esophagus (∼0.36 cm) since the esophagus is difficult to visualize on CT, especially in the lower thorax. Overall, visual comparison of GTV manual and auto contours showed good agreement. However, large discrepancies (up to 2cm) were found at the most inferior portion of the lung. This disagreement was also very evident from 3D maps of perpendicular distances between manually‐drawn and deformably‐mapped contours. Conclusion: Automatically‐generated contours using SICLE algorithm can produce high quality contours on subsequent respiratory CT phases. Deformable image registration may reduce or even eliminate the manual contouring workload and can be used for manually‐drawn contour quality assurance.Supported by NIHgrant‐P01CA11602
TU‐SAM‐BRB‐01: Model Based Dose Calculation Algorithms in External Radiation Therapy
Authors: Knoos T 
Published: April 2010

Accurate photon dose calculation models are today mainly based on dose calculation algorithms in which the dose distribution is predicted from first principles, i.e. model based algorithms. Basically a convolution is performed between the energy released in each voxel and a dose spread kernel. Due to limitations in computer speed and incomplete physics approximations have been introduced. They are to a first level the pencil beam convolution models and secondly the collapsed cone convolution models. This lecture will present these models and discuss the pros and cons for them and when possible also discuss the individual implementations in commercial treatment planning systems.The models covered are pencil beam models which today still are the basis for most dose calculations in 3DCRT and IMRT optimisations. Secondly, the new pencil beam implementation including modelling of changes in electron transport especially in the lateral direction will be discussed. Finally the highly accurate collapsed cone models will be covered which produce results of the same quality as Monte Carlo simulations. The latter approach is not the topic of this first part of the lecture, however, it will be used to benchmark results from model based algorithms and to highlight limitations of these.Learning Objectives:1. To provide an educational review of the physics and techniques behind model based algorithms e.g. convolution/superpositioning models.2. To review the methods used to improve the simulation efficiency i.e. pencil beam and collapsed cone convolutions.3. To briefly review the vendor codes currently used for clinical treatment planning.4. To briefly review the potential clinical implications of accurate calculated dose distributions.
TU‐SAM‐304A‐01: ACR MRI Accreditation Program Update
Authors: Reeve D 
Published: April 2010

In October 2008 the American College of Radiology (ACR) expanded the MRI accreditation program to six modules (body, head, MR angiography (MRA), spine, muskuloskeletal and cardiac). The new program enables accreditation of dedicated MR systems, such as those used only for neuro or cardiac imaging, as well as accreditation of special‐purpose MR scanners, such as orthopedic systems. The program introduces a second, smaller ACR phantom, to be used for accreditation and quality control of these small bore orthopedic MR systems.ACR MRI accreditation is now available for a wide range of MRI system configurations and clinical uses. The expansion of the program presents a challenge to the medical physicist, who needs to be aware of which ACR phantom and coil to use for phantom image acquisition, as well as how to address specific image quality issues.Learning Objectives:1. Present the requirements of the new six‐module ACR MRI accreditation program.2. Discuss the medical physicist/MRI scientist qualifications and CME requirements.3. Describe small and large phantom image acquisition and analysis.4. Discuss considerations for low field, 3T, dedicated and special purpose MRI systems in the accreditation and phantom image evaluation process.
TU‐A‐211A‐01: Margins in Radiation Therapy
Authors: Low D , Litzenberg D 
Published: April 2010

Conformal radiation therapy has historically used margins to account for geometrical uncertainties in the position of a target volume. The margins, in their simplest form, are simply expansions to the diameter of a treatment beam, to ensure that dosimetric planning criteria are met in the presence of inter‐ and intra‐fraction setup variations. Historically, the size of the margin in a given treatment site was difficult to determine due to the available technology and the time and effort required to obtaining accurate data. Consequently, margins were estimated to accommodate a population of patients. As new technologies have emerged, target volume position errors have become easier to measure, their accuracy has increased, and the measurements can be made much more frequently. As the quantity and quality of data has increased for patient populations, and even for individual patients, the conceptual basis of employing margins has evolved. Strategies for ensuring dosimetric coverage may now be individualized to a specific patient's geometric uncertainty characteristics with customized margins, or they may incorporate geometric correction based on predefined action levels. Other strategies may incorporate continuous monitoring to gate or modify the beam. And finally, other strategies seek to eliminate margins by including the estimated geometrical uncertainty into the development of the dose distribution.Learning Objectives:1. To provide an educational review of the technologies and methods of measuring target volume positioning errors.2. To review methods of determining population margins from measured data.3. To review corrective and intervention strategies for patients with individualized margins.4. To review planning strategies which seek to eliminate margins.