bluuebunny/crossref_metadata_2025_split huggingface dataset:
MO‐E‐211‐01: Breast MRI: Pulse Sequences, Acquisition Protocols, and Analysis
Authors: Price R 
Published: November 2011

Breast MRI is becoming an increasingly important diagnostic tool for evaluating breast cancer disease extent, monitoring therapy response and for screening women that are at high risk. The most common imaging protocol includes initial T2‐weighted bright‐fluid and pre‐contrast T1‐weighted 3D gradient‐echo (GE) sequences, followed by the injection of a gadolinium (Gd) contrast agent and a series of 3D‐GE images: dynamic contrast enhanced MRI (DCE‐MRI).Because of the high background signal in T1‐weighted images due to fatty tissues, it is preferred that all sequences be acquired with fat‐suppression. For images acquired without fat‐suppression, it is essential that image subtraction (post‐injection minus pre‐injection) be used to assure adequate contrast‐enhancement sensitivity.The sensitivity of DCE‐MRI for detecting cancerous lesions is determined by the degree of contrast enhancement that can be achieved relative to the surrounding normal tissues. The specificity of DCE‐MRI, for distinguishing malignant from benign lesions, relies upon the DCE‐MRI kinetic data. Malignant lesions generally exhibit rapid uptake and washout while benign lesions typically have a slower uptake that gradually increases with time. In an effort to achieve both the high sensitivity and specifically, breast MRI pulse sequences should be optimized to achieve high gadolinium contrast enhancement, high three‐dimensional spatial resolution (< 1 mm in‐plane) as well as adequate temporal resolution. The evolution of breast MR imaging has lead to the general use of fat‐suppressed, 3D T1‐weighted GE pulse sequences that can be acquired with a temporal resolution of approximately 60–90 seconds.Learning Objectives1. Review protocols and pulse sequences used for breast MR imaging.2. Review the MRI timing diagram used for T1‐weighted, fat‐suppressed, 3D gradient echo‐pulse sequences.3. Understand how k‐space sampling and parallel imaging affect temporal resolution.4. Review how parallel imaging can be used to help achieve the temporal resolution needed for breast DCE‐MRI.5. Discuss issues related to data acquisition and post‐acquisition image processing.
MO‐E‐211‐02: Breast MRI: Image Quality, Artifacts & Quality Control
Authors: Reeve D 
Published: November 2011

The quality of clinical breast MR images is influenced by the design and performance of the MR system, the breast coil, the breast MRI protocol, proper patient positioning, as well as patient‐specific factors. MR system and coil quality control, protocol optimization, and technologist training are important to ensure high quality breast MR images.Common image quality issues encountered in clinical breast MR image include signal non‐uniformity and inadequate breast tissue coverage, both of which can be influenced by the coil design. Inadequate fat or silicone saturation, wrap‐around artifacts, and parallel imaging artifacts can often be minimized through technologist training. Breast MR protocol modification may be necessary to achieve improvements in signal‐to‐noise ratio (SNR), high contrast spatial resolution, or artifact reduction. Low SNR or non‐ uniform breast MR images may be coil performance related. Therefore it is important that breast coils be tested annually and whenever coil performance issues are suspected, as part of a comprehensive MR system quality control program.Educational objectives:1. Describe common artifacts and image quality issues encountered in clinical breast MR images.2. Discuss methods for addressing breast MR image quality problems.3. Describe quality control procedures and accreditation programs specific to breast MRI.
MO‐F‐BRB‐06: Experimental Characterization of the Dosimetric Properties of a Newly Designed I‐Seed Model AgX100 125I Interstitial Brachytherapy Source
Authors: Chen Z , Bongiorni P , Nath R 
Published: November 2011

Purpose: To characterize and determine the dosimetric properties of a newly designed 125I source (Model AgX100 I‐Seed) for interstitial brachytherapy. Methods: High‐resolution photon spectrometry and thermoluminescent dosimetry (TLD) techniques were utilized for a comprehensive experimental characterization of the AgX100 source introduced recently by Theragenics Corporation® (Buford, GA). The photon characteristics emitted by the AgX100 source were determined by a high‐purity germanium spectrometer. The dose distributions around the source were measured using 1 mm &#61620; 1 mm &#61620; 1 mm TLD cubes placed in SolidWaterTM phantoms. The dosimetric parameters needed for dose calculation using the American Association of Physicists in Medicine (AAPM) Task Group (TG) No. 43 formalism were derived from the measured dose rate distributions with Monte Carlo calculated SolidWaterTM‐to‐water conversion factors. Results: It was found that 1) the photon energy spectrum emitted by the AgX100 source was nearly identical to that emitted by the well‐established model 6711 OncoSeedTM manufactured by GE Healthcare; 2) the dose‐rate constant determined by the photon spectrometry technique (0.957 ± 0.037 cGyh‐1U‐1) and by the TLD technique (0.995 ± 0.007 cGyh‐1U‐1) was within 1.5% of the corresponding values determined for the model 6711 source; 3) the radial dose function and the anisotropy function of the AgX100 source were also found to be similar to the TG‐43 consensus data for the model 6711 source. The anisotropy constant determined for the model AgX100 source (0.941) was virtually identical to the TG‐43 consensus value (0.942) for the model 6711 source. Conclusions: A comprehensive dosimetric characterization has been carried out for the new AgX100 source. The AAPM TG‐43 dosimetry parameters for the new source have been determined from the experiment data.The work was supported in part by NIH grant R01‐CA134627 and Theragenics Corporation
MO‐F‐214‐04: Protoyping Compositions of Novel Radiochromic Film Types: Towards Complete Absorbed Dose Energy Independence
Authors: Singh K , Sarfehnia A , Tomic N , Liang L , Deblois F , Seuntjens J , Lewis D , Shih H , Devic S 
Published: November 2011

Purpose: To develop a new generation energy‐independent radiochromic film over a wide energy range of 50 kVp to 18 MV. The films are preferably symmetric in structure and can be used for measurements in complex spectral distributions. Methods: The overall energy dependence and intrinsic energy dependence were measured for EBT2 and several prototype films of known compositions. The intrinsic energy response is quantified through a measurement of total energy response divided by the Monte Carlo calculated absorbed dose energy response. The measurements consisted of delivering an exact dose of 2 Gy to the sensitive layer of the film at both orthovoltage energies (50kVp, 120kVp, and 180kVp) and 60Co beam. Thus far, two iterations have been performed, whereby; numerical simulations are used to obtain an optimized absorbed dose energy response that will undo for the film intrinsic energy response. DOSRZnrc user‐code of the EGSnrc Monte Carlo code was used for all simulations. AAPM TG51 and TG61 were used to determine the dose‐to‐water and air‐kerma in air in megavoltage and orthovoltage beams, respectively, while Monte Carlo simulated corrections were used to convert these results to the desired dose to film. Results: For EBT2 films the overall energy dependence was found to vary by 35% over 50 kVp to Co‐60 energy range. The latest prototype measured in this work has shown a total net variation of 8% over the same range. High atomic number elements (Chlorine and bromine) were found to affect absorbed dose response drastically. The iterative optimization technique has placed a large focus in accurately determining the elemental composition. Conclusions: We have quantified the intrinsic energy dependence of radiochromic films, and have used the data to numerically optimize the composition of the active layer to produce an energy‐ independent film with an 8% energy variation over a wide energy range.Funding: This work was supported by the Natural Sciences and Engineering Research Council of Canada contract No. 386009.Conflict of interest: ISP is a manufacturing company of GAFCHROMICTM films.
MO‐F‐214‐06: Linear Energy Transfer Response of Polymer Gel Dosimeters in Therapeutic Proton Beams
Authors: Maryanski M , Lopatiuk‐Tirpak O , Su Z , Li Z , Zeidan O , Meeks S 
Published: November 2011

Purpose: preliminary investigation of the new unique formulation of BANG3‐Pro polymer gels for detecting and mapping local variations of LET in proton beam deliveries. Methods: Four polymer gel dosimeters — labeled A through D and employing four different systems of free‐radical chain‐termination and chain‐transfer—were irradiated by a 230 MeV proton beam in a spread‐out Bragg peak modulation (SOBP, 10 cm water‐ equivalent range, 6 cm width). The dosimeters were read out using an optical laser CT scanner OCTOPUS‐IQ, yielding three‐dimensional optical density distributions. All polymer gels and the laser CT scanner were developed and made by MGS Research, Inc. To illustrate the LET‐ dependent response variations, the residual signal was isolated by subtracting the PDD curve obtained by ion chamber measurements from the measured depth profiles of optical density, normalized to the proximal end of the SOBP. The residual signal was then spatially correlated to the analytically calculated depth profile of LET. Results: Three of the four dosimeters showed an over‐response (as compared with IC measurements) at the distal end of the SOBP consistent with their formulation. The peak magnitude of over‐response was 0%, 2%, 12%, and 17% for gels A, B, C, and D, respectively. Spatial correlation with calculated LET depth profiles revealed that gels A and B had no measurable dependence on LET and that gel C responded nearly linearly in the limited range from 1.5 to 2.3 keV/micrometer. The correlation between LET and optical response was most pronounced in gel D, where it was linear up to at least 3 keV/micrometer, with the response threshold at about 1.3 keV/micrometer. Conclusions: The free‐radical chain‐transfer and chain‐termination system in BANG3‐Pro type polymer gel dosimeters can be tailored to map distributions of LET, which may be used to better estimate the relative biological effectiveness of heavy‐ion radiotherapy treatments.This work was supported by the Bankhead‐Coley Florida Biomedical Research Program under Grant No. 1BD10‐34212.
MO‐F‐110‐05: Automation of PCXMC and ImPACT for NASA Astronaut Medical Imaging Dose and Risk Tracking
Authors: Bahadori A , Picco C , Flores‐McLaughlin J , Shavers M , Semones E 
Published: November 2011

Purpose: To automate astronaut organ and effective dose calculations from occupational X‐ray and computed tomography (CT) examinations incorporating PCXMC and ImPACT tools and to estimate the associated lifetime cancer risk per the National Council on Radiation Protection & Measurements (NCRP) using MATLAB®. Methods: NASA follows guidance from the NCRP on its operational radiation safety program for astronauts. NCRP Report 142 recommends astronauts be informed of the cancer risks from reported exposures to ionizing radiation from medical imaging. MATLAB® code was written to retrieve exam parameters for medical imaging procedures from a NASA database, calculate associated dose and risk, and return results to the database, using the Microsoft .NET Framework. This code interfaces with the PCXMC executable and emulates the ImPACT Excel spreadsheet to calculate organ doses from X‐rays and CTs, respectively, eliminating the need to utilize the PCXMC graphical user interface (except for a few special cases) and the ImPACT spreadsheet. Results: Using MATLAB® code to interface with PCXMC and replicate ImPACT dose calculation allowed for rapid evaluation of multiple medical imaging exams. The user inputs the exam parameter data into the database and runs the code. Based on the imaging modality and input parameters, the organ doses are calculated. Output files are created for record, and organ doses, effective dose, and cancer risks associated with each exam are written to the database. Annual and post‐flight exposure reports, which are used by the flight surgeon to brief the astronaut, are generated from the database. Conclusions: Automating PCXMC and ImPACT for evaluation of NASA astronaut medical imaging radiation procedures allowed for a traceable and rapid method for tracking projected cancer risks associated with over 12,000 exposures. This code will be used to evaluate future medical radiation exposures, and can easily be modified to accommodate changes to the risk calculation procedure.This research was supported by NASA Bioastronautics Contract NAS9‐ 02078.
MO‐F‐301‐01: Writing and Reviewing Papers for Medical Physics
Authors: Hendee W , Rogers D , Karellas A , Slattery P 
Published: November 2011

There is an art to writing a scientific paper so that it communicates accurately, succinctly, and comprehensively. Developing this art comes with experience, and sharing that experience with younger physicists is an obligation of senior scientists, especially those with editorial responsibilities for the journal. In this workshop, the preparation of a scientific manuscript will be dissected so participants can appreciate how each part is developed and then assembled into a complete paper. Then the review process for the paper will be discussed, including how to examine a paper and write an insightful and constructive review. Finally, we will consider the challenge of accommodating the concerns and recommendations of a reviewer in preparing a revision of the paper.A second feature of the workshop will be a discussion of the process of electronic submission of a paper for consideration by Medical Physics. The web‐based PeerX‐Press engine for manuscript submission and management will be examined, with attention to special features such as epaps and line‐ referencing. Finally, new features of Medical Physics will be explained, such as Vision 20/20 manuscripts, Physics Letters and the standardized formatting of book reviews.Education Objectives:1. Improve the participantsˈ abilities to write a scientific manuscript.2. Understand the review process for Medical Physics manuscripts and how to participate in and benefit from it.3. Appreciate the many features of the PeerX‐Press electronic management process for Medical Physics manuscripts.4. Develop a knowledge of new features of Medical Physics.
MO‐F‐220‐03: Has Elasticity Reached Clinical Maturity?
Authors: Milkowski A 
Published: November 2011

Elasticity is an ultrasound mode that provides mechanical stiffness information. Elasticity has been shown to provide an additional dimension of diagnostic information to anatomical (B‐mode) as well as vascular (Doppler) information.This presentation will start with a discussion of Elastography, defined as a manual palpation method, in which stiffness or strain images of soft tissue, particularly the breast, can be used to help detect or classify lesions.The presentation will continue with newer quantitative elasticity method called acoustic radiation force impulse imaging (ARFI). This method utilizes shear waves to provide quantitative and reproducible mechanical stiffness tissue properties.Lastly, a review of published clinical literature will show the developing consensus on the utilization of quantitative elasticity.
TU‐A‐BRB‐03: Simultaneous Optimization of Dose and LET in Proton Therapy Using Voronoi Partitions
Authors: Riofrio D , Keyes R , Maes D. , Luan S 
Published: November 2011

Purpose: Linear energy transfer (LET) is a measure of local energy deposition along the particle track. There is a positive correlation between relative biological effectiveness (RBE) and LET. As a result, LET painting has become a recent focus in particle therapy planning. The goal of this research is to develop a planning algorithm that can simultaneously optimize dose and LET distributions for particle therapy. Methods: It is well known that the high‐LET region of a charged particle beam is located at the distal edge of the Bragg peak. Therefore if a beam stops at the center of the target, its high LET region is also likely inside the target. This makes lower energy beams more preferable than high energy beams. Intuitively, this means each target voxel should be treated using its “closet” beam, or lowest possible energy beam. This observation makes Voronoi partition a natural choice for simultaneously optimizing dose and LET distributions, which given a set of objects partitions a metric space into cells, where each cell corresponds to a region closest to an object. A planning algorithm based on Voronoi partition has been implemented in C. Given a set of particle beams, the algorithm first partitions the target into a set of Voronoi cell, each corresponding to the region of the tumor closest to a beam. Then a constrained least square solver is used to determine the optimal plan with minimized beam energies, which simultaneously optimizes the LET distributions. Results: The planning algorithm has been tested on a skull base tumor using protons. A desired LET is observed inside the target, and dose and LET distributions are simultaneously optimized. Conclusions: Voronoi partition can guide the optimization to simultaneously optimize dose and LET distributions.Supported in part by Grants NSF CBET‐0755054 and NSF CBET‐0853157
TU‐A‐BRB‐05: Beam Controlled Arc Therapy: A Novel Delivery Concept for Stationary Targets
Authors: Zhang H , Betzel G , Yi B , DˈSouza W 
Published: November 2011

Purpose: To challenge the notion that the radiation beam must be held on as the gantry rotates around the patient and to describe a new approach for delivering intensity modulated arc therapy, beam‐controlled arc therapy (BCAT), during which the radiation beam is controlled on or off and the dose rate is modulated.Methods: Conventional IMAT presupposes that it is beneficial to delivery radiation from all beam angles as the gantry rotates, requiring the MLC to maintain continuity in shape from one angle to another. In turn, radiation from undesirable beam angles compromises the dose distribution. We propose a new approach to IMAT, BCAT, in which the radiation beam is held on or off and the dose rate is modulated while the gantry rotates around the patient. We employ linear‐programming‐based dose optimization to each aperture weight, resulting in some zero weight apertures. During delivery, the radiation beam is held off at control points with zero weights as the MLC shape transits to the next non‐zero weight shape. This was tested on 10 head and neck cases. Plan quality and delivery efficiency were compared with conventional IMAT.Results: Improvements in OAR sparing and target dose uniformity at dose/volume constraint levels were up to 18% (p‐value 0.002) and 67% (p‐value 0.04) respectively. Comparing to 180 and 360 apertures used in single‐arc and double‐arc IMAT plans, BCAT used 98 and 170 apertures on average respectively. The difference of total MUs used for IMAT and BCAT plans was less than 4%. Although BCAT resulted in a significant number of control points having zero MUs associated with them, the delivery times were comparable. Conclusions: Our results demonstrate that the BCAT approach, which allows the radiation beam to be controlled on and off, yields superior dosimetric results relative to the conventional IMAT while maintaining the delivery efficiency.NIH grant CA130814
TU‐C‐301‐02: Going Paperless in a Radiation Oncology Clinic
Authors: Nurushev T , Cormier A , Chetty I 
Published: November 2011

Utilization of paperless recordkeeping process is becoming mandatory under new and existing government regulations. While it is possible to implement the transition from paper and film based recordkeeping to paperless and filmless using a “head on” approach, it may be proven costly and inefficient. It is very beneficial to approach this transition in a systematic and thoughtful way to assure that the quality and accessibility of patient information is not compromised, but improved during such transition.Clinical flow in a typical department of Radiation Oncology includes processing and storing multitude of data related to patient health, treatment plan parameters, diagnostic and planning images, treatment records, including localization imaging. In addition to that extensive follow‐up data is stored. All this data has to be stored indefinitely, yet be readily available for access. A complete record should also include and patient‐specific QA tests.This lecture will provide a general overview of a typical data flow in a department of radiation oncology, and application of paperless tools available in Aria (Varian Medical Systems, Palo Alto, CA).Learning Objectives:1. Understand the documentation requirements for the clinical flow in a Radiation Oncology Department2. Understand the tools available within the vendor provided electronic patient record keeping system3. Understand the need to modify and adjust the paper‐based clinical flow when switching to paperless, to increase efficiency and convenience of accessing evidence data.
TU‐C‐220‐01: Three‐Dimensional Optoacoustic Tomography: Preclinical Research and Clinical Applications
Authors: Oraevsky A 
Published: November 2011

We developed a 3D optoacoustic tomography (OAT) system* combining advantages of pulsed optical spectroscopy and high‐resolution ultrasonic detection, characterized the system and demonstrated that it produces high‐ contrast 3D maps of optical absorbance through the large volume of tissue from 20 to 500 mL with resolution better than 0.5 mm. Applications of this technology range from the whole body imaging of a small animal for purposes of preclinical research in oncology to the diagnostic imaging of breast cancer and angiography. An ultrawide‐band of ultrasonic frequencies present in optoacoustic signals contains wealth of information, which can be revealed through proper filtering and post‐processing. The excellent contrast of hemoglobin and oxyhemoglobin in tissue allows one not only to see the circulatory system, but also to visualize the internal organs. Application of exogenous contrast agents permits imaging of microvasculature of tumors, spine, bones and joints. We demonstrated that either larger anatomy, such as organs or major vessels, or the smaller structures (kidney medullas, ovarian arteries) and even microvasculature can be visualized in case of sufficient contrast depending on methods of signal and image processing.The most significant value of 3D tomography employing a rigorous solution for the image reconstruction is to provide quantitative information of the absorption coefficient that can be translated into concentrations of tissue chromophores while imaging at several laser wavelengths. This system was employed to generate functional images of blood distribution and molecular images of malignancy‐related protein receptors in the cells of cancerous tumors in vivo. The most important parameter that enables clinical application is the depth of imaging. We demonstrated that the depth of optoacoustic imaging in tissues exceeds 50 mm for small blood vessel structures. Based on the experimental evidence, translation of the developed preclinical system to clinical applications will be discussed.