bluuebunny/crossref_metadata_2025_split huggingface dataset:
Neutral pH and copper ions promote eumelanogenesis after the dopachrome stage
Authors: Ito Shosuke , Suzuki Natsumi , Takebayashi Shiori , Commo Stéphane , Wakamatsu Kazumasa 
Published: July 2013

SummaryThe diversity of pigmentation in the skin, hair, and eyes of humans has been largely attributed to the diversity of pH in melanosomes with acidic pH being proposed to suppress melanin production. Tyrosinase has an optimum pH of 7.4 and its activity is suppressed greatly at lower pH values. The first step of eumelanogenesis is the oxidation of tyrosine to dopachrome (DC) via dopaquinone. However, how eumelanogenesis is controlled by pH beyond this stage is not known. In this study, we examined the effects of pH (5.3–7.3) on the conversion of DC to 5,6‐dihydroxyindole (DHI) and 5,6‐dihydroxyindole‐2‐carboxylic acid (DHICA) and the subsequent oxidation of DHI and DHICA to form eumelanin. The effects of Cu2+ ions on those reactions were also compared. The results indicate that an acidic pH greatly suppresses the late stages of eumelanogenesis and that Cu2+ ions accelerate the conversion of DC to DHICA and its subsequent oxidation.
Startle effects on saccadic responses to emotional target stimuli
Authors: Deuter Christian E. , Schilling Thomas M. , Kuehl Linn K. , Blumenthal Terry D. , Schachinger Hartmut 
Published: July 2013

AbstractStartle stimuli elicit various physiological and cognitive responses. This study investigated whether acoustic startle stimuli affect saccadic reactions in an emotional pro‐ or antisaccade task. Startle probes were presented either 500 ms before or simultaneous with an imperative stimulus that indicated whether a saccade towards or away from positive, neutral, or negative peripheral target pictures had to be performed. Valence interacted with saccade direction according to an approach‐avoidance pattern of gaze behavior, with delayed prosaccades to negative targets and antisaccades away from positive targets. Acoustic startle stimuli preceding the presentation of peripheral target pictures speeded up the initiation saccades, irrespective of stimulus valence. Results indicate a speeding of cognitive‐motor processing by preceding startle stimuli.
Maternal Social Coaching Quality Interrupts the Development of Relational Aggression During Early Childhood
Authors: Werner Nicole E. , Eaton Ashley D. , Lyle Kelsey , Tseng Heidi , Holst Brooke 
Published: July 2013

AbstractPrevious research has shown that parents of socially competent young children provide them with elaborative, explicit, appropriate, and emotion‐laden advice about peer interactions. The current study analyzed mothers' conversations with preschoolers (N = 175; 52 percent female; M age = 52 months, SD = 7 months) about peer conflicts involving relational aggression. Conversations were coded for maternal elaboration, emotion references, and discussion of norm violations. Information about relational and physical aggression was collected from teachers at two assessments approximately 12 months apart for a subsample of 136 children. Regression analyses, controlling for physical aggression, showed that average and high levels of effective coaching operated as a protective factor against stable high levels of relational aggression. Theoretical and practical implications for our understanding of the early development of relational aggression are discussed.
The Influence of Initiative Signature‐Gathering Campaigns on Political Participation
Authors: Boehmke Frederick J. , Alvarez R. Michael 
Published: July 2013

ObjectiveThis article studies the effect of initiative signature‐gathering campaigns on political participation within a state.MethodsUsing data on signatures gathered for eight initiatives and four different elections, we conduct grouped logit regression to test whether counties that are subject to more intense signature‐gathering campaigns, measured by the number of signatures gathered per capita, experience greater levels of turnout and ballot roll‐off in the subsequent election.ResultsOur analysis provides evidence that the intensity of signature‐gathering campaigns has a moderate effect on both of these measures of political participation.ConclusionInitiative campaigns influence turnout not just at the state level, but variation in campaigns leads to differences within states as well.
SU‐E‐J‐22: Implementation and Validation of a 2D‐3D Rigid Registration Algorithm for Proton Gantry and Stereotactic Radiosurgery Systems
Authors: Zhu M , Warmerdam G , Steininger P , Neuner M , Sharp G , Shih H , Winey B 
Published: July 2013

Purpose: To implement and validate the accuracy of an intensity‐based 2D to 3D rigid registration algorithm for proton treatment systems. Methods: A 2D‐3D rigid registration algorithm (REG23) was previously validated for linac machines. We adapted REG23 for use in both gantry‐based and Stereotactic Alignment in Radiosurgery (STAR) proton treatment systems. REG23 registration was run on NVIDIA Quadra600 GPU card using NCC metrics and AMOEBA optimizer and validated using dual orthogonal kV images acquired during cranial target treatments: 66 fractions to 7 patients in gantry system and 135 fractions to 9 patients in STAR. Rectangle ROIs covering the whole region superior to the base‐of‐skull were used for REG23 registration and the accuracy was evaluated using clinical utilized fiducial‐based 2D‐3D ray back‐projection rigid registration as the baseline. Results: For the gantry system, the differences between REG23 and baseline were ‐ 0.01±0.63 mm, 0.43±0.61 mm, 0.12±0.60 mm in the left‐right, superior‐inferior, and anterior‐posterior directions; 0.15±0.44°, 0.11±0.23°, and 0.19±0.37° in pitch, roll, and yaw, respectively. The vector difference was 1.04±0.48 mm. For STAR system, the REG23 results were − 0.34±0.45 mm, −0.10±0.36 mm, −0.38±0.75 mm, −0.14±0.54°, 0.04±0.18°, and 0.03±0.35° different than the baseline in the left‐right, superior‐inferior, and anterior‐posterior directions, pitch, roll, and yaw. The vector difference was 0.93±0.53 mm. The time for REG23 automatic registration was 29.7±9.5 seconds. Conclusion: We demonstrated that the intensity based 2D‐3D rigid registration algorithm REG23 provided sub‐millimeter accuracy and better than 0.5° for both gantry‐based and STAR proton treatment systems for cranial patients. This accuracy is within patient setup tolerance for current fractionated proton treatment systems. Given its accuracy and efficiency, we believe REG23 has great potential for clinical utilization in proton radiation therapy by replacing the implanted fiducial or anatomic feature based patient setup method.The project was supported by the Federal Share of program income earned by Massachusetts General Hospital on C06 CA059267, Proton Therapy Research and Treatment Center.
SU‐E‐T‐659: Inverse Treatment Planning for MERT Using Monte Carlo Calculations
Authors: Henzen D , Manser P , Frei D , Volken W , Neuenschwander H , Joosten A , Born EJ , Fix MK , Stampanoni M 
Published: July 2013

Purpose: The use of electron beams to treat shallow tumors cou ld reduce the dose to the distal organs at risk. To employ modulated electron radiotherapy (MERT) an inverse treatment planning strategy which bases on a Monte Carlo (MC) Electron Beam Model (EBM) has been developed. Methods: The inverse planning process starts with the selection of the SSD, gantry angle and co llimator rotation for each electron field. These fields are then divided into a grid of beamlets. An MC EBM together with the macro MC (MMC) dose calculation algorithm is employed to pre‐calculate the dose distribution for each beamlet. Afterwards a direct aperture optimization (DAO) using simulated annealing minimizes a co st function which is the sum of the squared dose differences in all voxels of the PTV and the OARs between the actual value and a given upper or lower limit. For each step either a weight change or an aperture change is initiated. As the beamlet dose calculation neglects the MLC interaction a post processing weight optimization and MLC aperture adjustment has been carried out after the DAO has been finished. To test the algorithm an inverse treatment plan has been created for an academic situation and co mpared to the obtained results using a previously developed forward planning strategy. Results: The implementation of an inverse optimization inco rporating the home made EBM has been completed successfully. The time needed for the DAO of the academic situation is about 30 min. Compared to the forward planning the inverse optimization is able to reduce the dose to the OAR (mean dose from 41% to 38%) for the academic case. Conclusion: The developed inverse optimization employing the EBM and MMC can be used for treatment planning of MERT. This work was supported by Varian Medical Systems.This work was supported by Varian Medical Systems.
MO‐A‐105‐01: Volumetric Modulated Arc Therapy
Authors: Shepard D , Popple R 
Published: July 2013

Volumetric Modulated Arc Therapy (VMAT) is a rotational approach to the delivery of intensity modulated radiation therapy (IMRT) that can be delivered on a conventional linear accelerator. VMAT has become a widely adopted clinical tool due to the conformal nature of the dose distributions and the efficiency of VMAT delivery. In this session, we will provide an overview of the VMAT delivery technique and will describe recommended steps for starting a VMAT program including VMAT commissioning, machine quality assurance, and patient‐specific quality assurance. We will describe commercial treatment planning systems and discuss tips and tricks for the use of VMAT for key clinical sites such as head‐and‐neck and prostate. Additionally, we will detail the role of VMAT for stereotactic radiosurgery (SRS) and stereotactic body radiation therapy (SBRT). More advanced VMAT topics will also be discussed such as flattening filter free VMAT, gated VMAT, and the use of couch rotations during VMAT delivery.Learning Objectives:1. Describe volumetric modulated arc therapy (VMAT).2. Describe commissioning of a VMAT delivery system.3. Summarize the key elements of starting a VMAT program.4. Review patient‐and machine‐specific VMAT quality assurance.5. Survey VMAT treatment planning systems and planning techniques.6. Describe advanced VMAT techniques such as gated VMAT and flattening filter free VMAT.Conflict of Interest: Richard Popple has a sponsored research agreement with Varian. David Shepard has a sponsored research agreement with Elekta.Richard Popple has a sponsored research agreement with Varian. David Shepard has a sponsored research agreement with Elekta.
MO‐A‐116‐01: TG151: Radiographic System Quality Control
Authors: Hulme K , Arbique G 
Published: July 2013

Quality control (QC) in medical imaging is often viewed as a series of infrequent, detailed evaluations of a piece of medical imaging equipment by a qualified medical physicist (QMP). The day‐to‐day operational process is largely neglected absent regulatory or accreditation requirements. However, QC should be viewed as an ongoing process that occurs on an image‐by‐image basis. Ongoing QC was inherent in the screen‐film imaging workflow, where rejected image rates were calculated by counting rejected films and improperly exposed films resulted in images that were too dark or light and were repeated out of necessity, and the rejected films counted. During the early years of the shift to digital imaging in radiography, ongoing QC was largely abandoned, owing to both a perceived lack of need and difficulty in performing ongoing QC with early digital imaging systems, which lacked standardized exposure indicators and tools for counting rejected images.The QC process involves key personnel in the imaging department, including the radiologist, radiologic technologist, and QMP. The radiologist administers and oversees the QC program, which is carried out by the radiologic technologist. The radiologic technologists collects and analyzes data, and results that are outside the acceptance levels for the QC program are investigated, and corrective action taken to bring these results back to an acceptable level. The QMP consults with the radiologist in the design and implementation of the QC program, works with the technologist to triage problems, and carefully evaluates the imaging equipment on a regular basis for proper calibration, function, and compliance with applicable regulations. The continued need for ongoing QC in digital radiography has been highlighted in the scientific literature, and Task Group 151 was charged with recommending consistency tests designed to be performed by a QMP, or a radiologic technologist under the direction of a QMP, to identify problems with an imaging system that need further evaluation by a QMP, including a fault tree to define actions that need to be taken when certain fault conditions are identified. The focus of the final report of TG 151 was the ongoing QC process, including rejected image analysis, ongoing exposure analysis, and artifact identification. These three QC tasks are vital for the optimal operation of a department performing digital radiography.Learning Objectives:1. Learn methods for performing rejected image analysis in digital radiography, including learning trends and patterns that are common2. Learn methods for performing ongoing exposure analysis in digital radiography, including learning trends and patterns that are common3. Understand how to incorporate ongoing QC into your radiography department
MO‐D‐137‐01: ABR Update
Authors: Allison J , Ibbott G , Frey G 
Published: July 2013

This session will present a review of the ABR requirements and policies for the initial certification of medical physicists. Changes in the program that have occurred in the last several years will be discussed. The requirements for certification for 2014 and beyond will be reviewed. Changes in the oral exam and the board eligibility policy will be presented he MOC program will also be reviewed. The changes that occurred in 2013 will be emphasized. These include the change to continuous MOC, easy public access to certification status and the new ABR My ABR website. There will be adequate time for questions and group discussion.Learning Objectives:1. The participant will understand the role of the ABR in the certification of medical physicists.2. The participant will understand the ABR requirements for Medical Physics Certification.3. he participant will understand the requirements for participation the ABR's Maintenance of Certification process.
MO‐F‐141‐01: X‐Ray Tubes for Medical Imaging
Authors: Behling R 
Published: July 2013

Why do we find 500+ types of X‐ray tubes on the market? Why still vacuum technology to generate Bremsstrahlung, ca. 120 years after Conrad Roentgen's discovery? How do X‐ray tubes function and look like? What's next? (When?) Will we see the X‐ray LED' s, compact X‐ray Lasers or flat panel sources in medical imaging? These and more questions will be answered in this lecture. We will shortly dive into physics of X‐ray generation, study key characteristics, material boundary conditions, manufacturing technology. We will identify the quality parameters, which allow us to compare and select the proper source.In more detail we will understand design concepts of glass and metal frame, single ended and dual polar tubes, stationary anode tubes with reflection and transmission targets. We will devote a larger portion to rotating anode tubes, their bearings, anode discs, motors, cooling, heat balance. We will talk about electron emitters and beam focusing, focal spot characteristics, MTF, off‐focal radiation, focal spot deflection, stability. Side effects need to be mentioned like leakage and scattered radiation. Tube life will be discussed, ageing effects, failure pareto distributions, end‐of‐life indicators and overall cost drivers.Employee of Philips Healthcare
MO‐F‐103‐01: Estimating Risk of Low Radiation Doses
Authors: Hendee W , O' Connor M , Calabrese E 
Published: July 2013

Several articles in the medical literature over the past few years have predicted thousands of cancers and cancer deaths annually in the US population caused by radiation exposures from medical imaging. The predictions are derived from risk estimates in the National Academy of Sciences BEIR VII report. These risk estimates are highly speculative with wide confidence intervals, and the BEIR VII committee has warned against using them to estimate cancer risks to individuals or populations. They are based on risk models derived from the linear no‐threshold hypothesis of radiation risk at low doses. This hypothesis is derived from studies in the 1920s and 30s of genetic mutations in x‐irradiated Drosophila and has a history of controversy and conflict. It has been challenged by experiments at the cellular and animal levels as well as by data of cancer incidence in medically‐, occupationally‐, and environmentally‐exposed individuals. The main source of data for the BEIR VII risk estimates are the survivors of the Japanese A‐bomb explosions, a population greatly different from the US population that was exposed to radiation conditions greatly different from those of medical imaging. Even so, data from the Japanese studies frequently reveal a threshold dose for increased cancers in the irradiated populations. Collectively, the uncertainties in the derivation of the BEIR VII risk estimates, and the intrinsic speculative nature of the risk estimates themselves, cause predictions of cancers and cancer deaths to be more hypothetical than real in populations exposed to medical imaging. Several scientific organizations, including the Health Physics Society, American Association of Physicists in Medicine, the International Organization of Medical Physicists, the United Nations Scientific Committee on the Effects of Atomic Radiation, and the International Commission on Radiological Protection, have warned against making such predictions because of their speculative nature. Unfortunately, these hypothetical predictions of cancer risks are themselves a health risk, because they create anxiety in patients resulting in a reluctance to undergo medical imaging procedures prescribed for their benefit.Learning Objective:1. Understand the origin of cancer risk estimates in BEIR VII2. Appreciate the limitations in applying Japanese health data to American patients3. Be familiar with the history and limitations of the LNT model of radiation injury
MO‐F‐116‐01: Statistics, Error Analysis, and Uncertainty Reporting in Medical Physics
Authors: Guo F , Ruan D , Cui J 
Published: July 2013

Medical physics is a branch of physics so the rules with error analysis and uncertainty reporting of measurements, should be same and observed. In reality, these rules are not obeyed very well as an observation of the clinical practice shows. Partial of the causes is that physicists are from different backgrounds which have different degrees of following the requirements on applying these rules. Another reason is that clinical physicists are part of a treatment team in which other members don' t necessarily have same strict requirements as physicist should have. To communicate with other treatment members, physicists trend to use layman terms to express the physics terms which should be in a strict format. This lecture is to refresh clinical physicist's knowledge on these issues. Basic knowledge of statistics, error analysis, and uncertainty reporting will be review with examples from clinical setups, such as AAPM TG‐51 calibration, TG‐119, in‐vivo dose measurements, and treatment planning calculations. For example, how many readings should you take when a TG‐51 calibration is performed? What is the associated uncertainty with each Result? How many effective numbers should you keep there? Should it be whatever numbers since the excel spreadsheet can easily give you whatever digitals? Those sound trivia but if you take a look at your colleague's or friend's reports, they are worth of further scrutinizing. After this lecture, hopefully practicing physicists have clearer ideas about statistics, error analysis, and uncertainty reporting in their daily clinic work.Learning Objectives:1. To refresh clinical physicist's knowledge about statistics, error analysis, and uncertainty reporting in medical physics.2. Clearer ideas to apply these rules in their daily clinic work.3. Improve the clinical practice.
MO‐F‐144‐01: Ultrasound Guided Systems for RT and Treatment Planning
Authors: Hsu I , Hristov D , Salter B , Fontanarosa D 
Published: July 2013

The history of radiation therapy treatment planning and delivery has been one of constant improvement in the accuracy and precision of target identification, target localization, and dose delivery. The demands on delivery have now crossed a threshold where radiation therapy is inherently dependent on image guidance as a standard of care. While much image guidance in RT is acquired with ionizing radiation modalities such as CT and fluoroscopy, ultrasound has always played a role in specialized situations. However, improving technologies for ultrasound transducers, spatial transducer localization, post‐acquisition image analysis, and automated control of acquisition parameters are creating new opportunities for ultrasound across the breadth of radiation oncology. This education session will highlight several new developments in the use of ultrasound imaging for radiation therapy treatment planning and delivery. Topics will include:* Real‐time telerobotic 3D ultrasound for soft‐tissue guidance concurrent with beam delivery* US for prostate positioning ‐ Trans‐perineal approach combined with real‐time monitoring* Challenges and opportunities of trans‐rectal ultrasound (TRUS)‐based prostate HDR brachytherapy* Speed of sound aberration evaluation and correction in ultrasound‐guided radiation therapy applications This session is intended to provide a window into how ultrasound can be used to meet the demand for a non‐ionizing, non‐invasive, real‐time image guidance solution. Attendees to the session should expect to meet the following:Learning Objectives:1. Understand the advantages and disadvantages of trans‐rectal and trans‐perineal approaches for ultrasound imaging during prostate HDR2. Understand the current limitations of ultrasound for quantitatively imaging heterogeneous tissue as well as methods for detecting and correcting aberrations in soft tissue.3. Learn how spatial tracking of ultrasound transducers and standardization of ultrasound acquisition techniques through the use of robotics can make ultrasound a viable solution for anatomical motion during radiation therapy procedures.David Schlesinger has a research grant from Elekta, AB unrelated to the topic of this session.