bluuebunny/crossref_metadata_2025 huggingface dataset:
Right Ventricular Endomyocardial Fibrosis (2013 Grover Conference Series)
Authors: Mocumbi Ana Olga
Published: July 2014

Endomyocardial fibrosis (EMF) is a restrictive cardiomyopathy of unknown origin, affecting predominantly the right side of the heart. Its highest prevalence is in poor regions of sub‐Saharan Africa, where it is usually found in children and adolescents. In areas where it is endemic, EMF is a major cause of heart failure and premature death. EMF of the right ventricle has unique clinical, electrocardiographic, and echocardiographic signs. Several features of advanced disease are not fully understood, the most striking being the presence of severe ascites with little or no pedal edema. Echocardiography is the main diagnostic tool and supports management of the disease in most patients, as it allows assessment of the severity and extension of endocardial fibrosis, the quality of the right atrioventricular valve, and the presence of intracardiac thrombi. Pulmonary hypertension in the setting of right EMF is related to chronic thromboembolism, through the chronic thrombi present in the severely enlarged right atrium found in advanced disease. The management of right EMF is difficult. Treatment of symptomatic patients should be surgical. However, as the disease is usually detected in late stages, with severe and advanced lesions, surgery cannot be performed without a very high risk of death and complications. New surgical approaches addressing several components of the structural cardiac abnormalities have been attempted, with promising results. EMF remains one of the most neglected diseases worldwide, and research into its pathophysiological mechanisms will probably improve outcomes and alter the natural history of the disease. This requires improvement in the health systems in areas of endemicity as well as the design of international collaborative research projects.
Experimental Investigation of the Heat Transfer Performance of a Hybrid Cooling Fin Thermosyphon
Authors: Pappas Christina A. , Jordan Donald A. , Norris Pamela M.
Published: July 2014

The effect of fill volume on the heat transfer performance of a hybrid cooling fin thermosyphon, characterized by an airfoil cross-sectional shape and a slot-shaped cavity, is investigated. The performance was examined at three fill volumes, expressed as a percentage of the evaporator section: 0%, 60%, and 240%. These were chosen to represent three distinct regimes: unfilled, filled, and overfilled evaporator sections, respectively. The cross section of this copper–water thermosyphon has a NACA0010 shape with a chord length of 63.5 mm and an aspect ratio (ratio of the length of the evaporator section to the cavity width) of 1.109. The evaporator length comprises 8.3% of the total thermosyphon length. The air-cooled condenser section was placed in a uniform air flow in the test section of an open return wind tunnel. The rate of heat transfer, or performance, was measured as a function of fill volume and evaporator temperature. The heat transfer performance increased by 100–170% by adding 0.86 ml of working fluid (de-ionized water), i.e., when the fill volume increased from 0% to 60%, which illustrates the improvement of a cooling fin's heat transfer rate by converting it to a hybrid cooling fin thermosyphon. Of the fill volumes investigated, the thermosyphon achieves a maximum heat transfer rate and highest average surface temperature at the 60% fill volume. Overfilling the evaporator section at 240% fill results in a slight decrease in performance from the 60% fill volume. The results of this study demonstrate the feasibility of hybridizing a cooling fin to act both as a cooling fin and a thermosyphon.
Energy and Reserve Co-optimization of a Combined Cycle Plant Using Mixed Integer Linear Programming
Authors: Campos F. A. , Reneses J.
Published: July 2014

The growth in the importance of interruptible sources of energy is increasing the concerns of many electricity market regulators with respect to the reliability and stability of electricity supply. Decisions such as that to increase the number of reserve markets, their reserve requirements, or the role of reserve prices in the final electricity price have meant that generation plants are currently often operating with strategies to obtain not only large energy market quotes but also reserve ones. In this paper, a mixed integer linear programming (MILP) model is proposed to obtain the energy and reserve dispatch of a real combined cycle plant (CCP) to optimize its use on a weekly or annual basis. The dispatch is optimal in the sense that it maximizes the joint energy and reserve profits, including an estimation of the energy and reserve prices. The detailed technical and economic characteristics of the plant have been considered, such as start-ups, shut-downs, minimum hours for steam generation, supplementary firing, or natural gas contracts. The cases studies validate the main features of the mathematical model and analyze the computational efficiency in a realistic simulation.
Realistic Finite Element Simulations of Arc-Height Development in Shot-Peened Almen Strips
Authors: Chen Zhuo , Yang Fan , Meguid S. A.
Published: July 2014

It is the objective of this study to conduct realistic simulations of the arc-height development in shot-peened Almen strips using the finite element (FE) method. Unlike our earlier work which is devoted to relaxation of shot peening induced residual stress, in this paper, the focus is on peen forming as a result of repeated spherical impingement. Specifically, a 3D FE model with 1500 randomly distributed shots bombarding an Almen strip was developed. Strain rate dependent plasticity was considered and an artificial material damping was applied to control the undesired high-frequency oscillations. The solution further adopts both explicit dynamic and implicit quasi-static analyses to simulate the entire arc-height development in the Almen strips. Quantitative relationships between the resulting equivalent plastic strain and the associated residual stress distribution for a given shot velocity and shot numbers are established and discussed. The work also considers the effect of repeated impacts upon the induced residual stress field using a large number of random shots. Attention was further devoted to the effect of the strip constraint upon the outcome of the impingement. Our results indicate that the proposed FE model is a powerful tool in investigating the underlying mechanisms of the peening treatment.
Isotope effects on plasma species of Ar/H2/D2 plasmas
Authors: Fox-Lyon Nick , Oehrlein Gottlieb S.
Published: July 2014

The authors studied the influence of isotopes on the Ar/H2 and Ar/D2 plasmas using Langmuir probe and ion mass analyzer measurements at several pressures relevant to low temperature plasma surface processing. As up to 50% H2 is added to Ar plasma, electron energy distribution functions show an increase in electron temperature (from 2.5 eV to 3 eV for 30 mTorr with 50% addition) and a decrease in electron density (2.5 × 1011 cm−3 → 2.5 × 1010 cm−3 at 30 mTorr with 50% addition). At lower pressures (5 and 10 mTorr), these effects are not as pronounced. This change in electron properties is very similar for Ar/D2 plasmas due to similar electron cross-sections for H2 and D2. Ion types transition from predominantly Ar+ to molecular ions ArH+/H3+ and ArD+/D3+ with the addition of H2 and D2 to Ar, respectively. At high pressures and for the heavier isotope addition, this transition to molecular ions is much faster. Higher pressures increase the ion–molecules collision induced formation of the diatomic and triatomic molecular ions due to a decrease in gaseous mean-free paths. The latter changes are more pronounced for D2 addition to Ar plasma due to lower wall-loss of ions and an increased reaction rate for ion–molecular interactions as compared to Ar/H2. Differences in plasma species are also seen in the etching behavior of amorphous hydrocarbon films in both Ar/H2 and Ar/D2 plasma chemistries. D2 addition to Ar plasma shows a larger increase in etch rate than H2 addition.
SU‐E‐T‐331: To Evaluate Planning Quality of SBRT with Multiple Lung Metastases Generated with Pinnacle and Tomotherapy
Authors: Chen Y , Zhang Y , Zhang Y , Doxsee K , Yang C
Published: July 2014

Purpose:

To evaluate planning quality of SBRT with multiple lung metastases generated with Pinnacle and Tomotherapy

Methods:

Nine randomly selected patients diagnosed with non small‐cell lung cancer with multiple lesions were planned with Pinnacle (version 9.2) and Tomotherapy (version 4.2). Coplanar and non_coplanar plans were generated on Pinnacle. A total dose of 60 Gy was prescribed to 95% of PTV in 3 fractions. Single isocenter was used. Nine static beams were used for Pinnacle plans. Planning outcomes such as minimum and mean dose, V9 5, D9 5 (95% of target volume receives prescription dose), D5, and D1 to PTV, maximum dose to heart, esophagus, cord, trachea, brachial plexus, rib, chest wall, and liver, mean dose to liver, total lung, right and left lung, volume of chest wall receives 30 Gy, volume of lungs receives 5 Gy and 20Gy, conformity index (CI = PIV / PTV) and heterogeneity index (HI = D5 / D9 5) were reported for evaluation.

Results:

The mean volume of PTV was 37.77 ± 23.4 cm3. D9 5 of PTV with Tomo, coplanar, non_coplanar was 60.2 ± 0.3 Gy, 58.6 ± 1.2 Gy, and 59.1 ± 0.7 Gy, respectively. Mean dose to PTV was lower for Tomo (p < 0.0001), so were D5 (p < 0.0001) and D1 (p = 0.001). CI was better with Tomo (p < 0.0001), so was HI (p < 0.0001). Maximum dose to other critical organs were also lower exclusively with Tomo plans. Treatment time was recorded only for Tomo plans (73.0 ± 20.6 min).

Conclusion:

With 51 beam angles, Tomo plans could generally achieve better tumor coverage while sparing more critical structures for multiple lung lesions study. Non_coplanar also has better tumor coverage with lower dose to critical organs such as lungs, liver, chest wall and cord compare to coplanar plans.
SU‐E‐T‐335: Transit Dosimetry for Verification of Dose Delivery Using Electronic Portal Imaging Device (EPID)
Authors: Baek T , Chung E , Lee S , Yoon M
Published: July 2014

Purpose:

To evaluate the effectiveness of transit dose, measured with an electronic portal imaging device (EPID), in verifying actual dose delivery to patients

Methods:

Plans of 5 patients with lung cancer, who received IMRT treatment, were examined using homogeneous solid water phantom and inhomogeneous anthropomorphic phantom. To simulate error in patient positioning, the anthropomorphic phantom was displaced from 5 mm to 10 mm in the inferior to superior (IS), superior to inferior (SI), left to right (LR), and right to left (RL) directions. The transit dose distribution was measured with EPID and was compared to the planed dose using gamma index.

Results:

Although the average passing rate based on gamma index (GI) with a 3% dose and a 3 mm distance‐to‐dose agreement tolerance limit was 94.34 % for the transit dose with homogeneous phantom, it was reduced to 84.63 % for the transit dose with inhomogeneous anthropomorphic phantom. The Result also shows that the setup error of 5mm (10mm) in IS, SI, LR and SI direction can Result in the decrease in values of GI passing rates by 1.3% (3.0%), 2.2% (4.3%), 5.9% (10.9%), and 8.9% (16.3%), respectively.

Conclusion:

Our feasibility study suggests that the transit dose‐based quality assurance may provide information regarding accuracy of dose delivery as well as patient positioning.
SU‐E‐T‐347: Validation of the Condensed History Algorithm of Geant4 Using the Fano Test
Authors: Lee H , Mathis M , Sawakuchi G
Published: July 2014

Purpose:

To validate the condensed history algorithm and physics of the Geant4 Monte Carlo toolkit for simulations of ionization chambers (ICs). This study is the first step to validate Geant4 for calculations of photon beam quality correction factors under the presence of a strong magnetic field for magnetic resonance guided linac system applications.

Methods:

The electron transport and boundary crossing algorithms of Geant4 version 9.6.p02 were tested under Fano conditions using the Geant4 example/application FanoCavity. User‐defined parameters of the condensed history and multiple scattering algorithms were investigated under Fano test conditions for three scattering models (physics lists): G4UrbanMscModel95 (PhysListEmStandard_option3), G4GoudsmitSaundersonMsc (PhysListEmStandard_GS), and G4WentzelVIModel/G4CoulombScattering (PhysListEmStandard_WVI). Simulations were conducted using monoenergetic photon beams, ranging from 0.5 to 7 MeV and emphasizing energies from 0.8 to 3 MeV.

Results:

The GS and WVI physics lists provided consistent Fano test results (within ±0.5%) for maximum step sizes under 0.01 mm at 1.25 MeV, with improved performance at 3 MeV (within ±0.25%). The option3 physics list provided consistent Fano test results (within ±0.5%) for maximum step sizes above 1 mm. Optimal parameters for the option3 physics list were 10 km maximum step size with default values for other user‐defined parameters: 0.2 dRoverRange, 0.01 mm final range, 0.04 range factor, 2.5 geometrical factor, and 1 skin. Simulations using the option3 physics list were ∼70 – 100 times faster compared to GS and WVI under optimal parameters.

Conclusion:

This work indicated that the option3 physics list passes the Fano test within ±0.5% when using a maximum step size of 10 km for energies suitable for IC calculations in a 6 MV spectrum without extensive computational times. Optimal user‐defined parameters using the option3 physics list will be used in future IC simulations to calculate beam quality correction factors under the presence of a magnetic field.

Elekta‐MD Anderson Research Agreement
SU‐E‐T‐350: Verification of Gating Performance of a New Elekta Gating Solution: Response Kit and Catalyst System
Authors: Xie X , Cao D , Housley D , Mehta V , Shepard D
Published: July 2014

Purpose:

In this work, we have tested the performance of new respiratory gating solutions for Elekta linacs. These solutions include the Response gating and the C‐RAD Catalyst surface mapping system.Verification measurements have been performed for a series of clinical cases. We also examined the beam on latency of the system and its impact on delivery efficiency.

Methods:

To verify the benefits of tighter gating windows, a Quasar Respiratory Motion Platform was used. Its vertical‐motion plate acted as a respiration surrogate and was tracked by the Catalyst system to generate gating signals. A MatriXX ion‐chamber array was mounted on its longitudinal‐moving platform. Clinical plans are delivered to a stationary and moving Matrix array at 100%, 50% and 30% gating windows and gamma scores were calculated comparing moving delivery results to the stationary result. It is important to note that as one moves to tighter gating windows, the delivery efficiency will be impacted by the linac's beam‐on latency. Using a specialized software package, we generated beam‐on signals of lengths of 1000ms, 600ms, 450ms, 400ms, 350ms and 300ms. As the gating windows get tighter, one can expect to reach a point where the dose rate will fall to nearly zero, indicating that the gating window is close to beam‐on latency. A clinically useful gating window needs to be significantly longer than the latency for the linac.

Results:

As expected, the use of tighter gating windows improved delivery accuracy. However, a lower limit of the gating window, largely defined by linac beam‐on latency, exists at around 300ms.

Conclusion:

The Response gating kit, combined with the C‐RAD Catalyst, provides an effective solution for respiratorygated treatment delivery. Careful patient selection, gating window design, even visual/audio coaching may be necessary to ensure both delivery quality and efficiency.

This research project is funded by Elekta.
SU‐E‐T‐490: Clinical Analysis of the Approximate Multi‐Phase Biological Effective Dose (BED) Calculation
Authors: Kauweloa K , Gutierrez A , Bergamo A , Stathakis S , Papanikolaou N , Mavroidis P
Published: July 2014

Purpose:

An approximate, multi‐phase biological effective dose (BED) equation was introduced to simplify 3D‐BED calculations by treatment planning systems. The purpose of this work is to analyze its clinical accuracy within patients receiving two phase treatments (e.g., primary and boost phases).

Methods:

Twenty prostate and brain cancer patients were studied. MATLAB was used to calculate the true‐BED (BEDT) and approximate‐BED (BEDA), on a voxel‐basis within both phases, using the physical dose matrices that were exported from Pinnacle3 (Philips Medical, Fitchburg, WI). The data was analyzed using the percent error equation of BEDA with respect to BEDT. The Bland‐Altman Analysis and the Pearson's Correlation Coefficient were also used in order to study the impact of the dose distributions on the accuracy of BEDA.

Results:

It was shown that when the dose‐per‐fractions (DPF) between both phases were equal, the error was zero. Within brain cancer patients, 50 percent of the Optic Chiasms and Brainstems, 60–70 percent of the Left and Right Optic Nerves, and 80 percent of the Normal Brain and Spinal Cord had a BEDA with less than a 1 percent error. For prostate cancer patients, 60–70 percent of the Rectum and Bladder also had a BEDA with less than a 1 percent error. The BA‐Analysis and PCC also revealed the significant impact of the dose distribution and the locations of the OAR and target on the accuracy of BEDA.

Conclusion:

The results displayed accurate BEDA calculations in certain cases such as the Normal Brain, yet patients with large errors still existed. Due to the imprecision of BEDA on OARs, and the difficulty in predicting when it would be accurate, we recommend using BEDA only for targets due to a greater probability of seeing equivalent DPF values in both phases because of the homogeneous dose distributions delivered to the target volumes.
SU‐E‐T‐491: Importance of Energy Dependent Protons Per MU Calibration Factors in IMPT Dose Calculations Using Monte Carlo Technique
Authors: Randeniya S , Mirkovic D , Titt U , Guan F , Mohan R
Published: July 2014

Purpose:

In intensity modulated proton therapy (IMPT), energy dependent, protons per monitor unit (MU) calibration factors are important parameters that determine absolute dose values from energy deposition data obtained from Monte Carlo (MC) simulations. Purpose of this study was to assess the sensitivity of MC‐computed absolute dose distributions to the protons/MU calibration factors in IMPT.

Methods:

A “verification plan” (i.e., treatment beams applied individually to water phantom) of a head and neck patient plan was calculated using MC technique. The patient plan had three beams; one posterior‐anterior (PA); two anterior oblique. Dose prescription was 66 Gy in 30 fractions. Of the total MUs, 58% was delivered in PA beam, 25% and 17% in other two. Energy deposition data obtained from the MC simulation were converted to Gy using energy dependent protons/MU calibrations factors obtained from two methods. First method is based on experimental measurements and MC simulations. Second is based on hand calculations, based on how many ion pairs were produced per proton in the dose monitor and how many ion pairs is equal to 1 MU (vendor recommended method). Dose distributions obtained from method one was compared with those from method two.

Results:

Average difference of 8% in protons/MU calibration factors between method one and two converted into 27 % difference in absolute dose values for PA beam; although dose distributions preserved the shape of 3D dose distribution qualitatively, they were different quantitatively. For two oblique beams, significant difference in absolute dose was not observed.

Conclusion:

Results demonstrate that protons/MU calibration factors can have a significant impact on absolute dose values in IMPT depending on the fraction of MUs delivered. When number of MUs increases the effect due to the calibration factors amplify. In determining protons/MU calibration factors, experimental method should be preferred in MC dose calculations.

Research supported by National Cancer Institute grant P01CA021239
SU‐E‐T‐492: Implementing a Method for Brain Irradiation in Rats Utilizing a Commercially Available Radiosurgery Irradiator
Authors: Cates J , Drzymala R
Published: July 2014

Purpose:

The purpose of the study was to implement a method for accurate rat brain irradiation using the Gamma Knife Perfexion unit. The system needed to be repeatable, efficient, and dosimetrically and spatially accurate.

Methods:

A platform (“rat holder”) was made such that it is attachable to the Leskell Gamma Knife G Frame. The rat holder utilizes two ear bars contacting bony anatomy and a front tooth bar to secure the rat. The rat holder fits inside of the Leskell localizer box, which utilizes fiducial markers to register with the GammaPlan planning system. This method allows for accurate, repeatable setup.A cylindrical phantom was made so that film can be placed axially in the phantom. We then acquired CT image sets of the rat holder and localizer box with both a rat and the phantom. Three treatment plans were created: a plan on the rat CT dataset, a phantom plan with the same prescription dose as the rat plan, and a phantom plan with the same delivery time as the rat plan.

Results:

Film analysis from the phantom showed that our setup is spatially accurate and repeatable. It is also dosimetrically accurate, with an difference between predicted and measured dose of 2.9%. Film analysis with prescription dose equal between rat and phantom plans showed a difference of 3.8%, showing that our phantom is a good representation of the rat for dosimetry purposes, allowing for +/‐ 3mm diameter variation. Film analysis with treatment time equal showed an error of 2.6%, which means we can deliver a prescription dose within 3% accuracy.

Conclusion:

Our method for irradiation of rat brain has been shown to be repeatable, efficient, and accurate, both dosimetrically and spatially. We can treat a large number of rats efficiently while delivering prescription doses within 3% at millimeter level accuracy.
SU‐E‐T‐495: Neutron Induced Electronics Failure Rate Analysis for a Single Room Proton Accelerator
Authors: Knutson N , DeWees T , Klein E
Published: July 2014

Purpose:

To determine the failure rate as a function of neutron dose of the range modulator's servo motor controller system (SMCS) while shielded with Borated Polyethylene (BPE) and unshielded in a single room proton accelerator.

Methods:

Two experimental setups were constructed using two servo motor controllers and two motors. Each SMCS was then placed 30 cm from the end of the plugged proton accelerator applicator. The motor was then turned on and observed from outside of the vault while being irradiated to known neutron doses determined from bubble detector measurements. Anytime the motor deviated from the programmed motion a failure was recorded along with the delivered dose. The experiment was repeated using 9 cm of BPE shielding surrounding the SMCS.

Results:

Ten SMCS failures were recorded in each experiment. The dose per monitor unit for the unshielded SMCS was 0.0211 mSv/MU and 0.0144 mSv/MU for the shielded SMCS. The mean dose to produce a failure for the unshielded SMCS was 63.5 ± 58.3 mSv versus 17.0 ±12.2 mSv for the shielded. The mean number of MUs between failures were 2297 ± 1891 MU for the unshielded SMCS and 2122 ± 1523 MU for the shielded. A Wilcoxon Signed Ranked test showed the dose between failures were significantly different (P value = 0.044) while the number of MUs between failures were not (P value = 1.000). Statistical analysis determined a SMCS neutron dose of 5.3 mSv produces a 5% chance of failure. Depending on the workload and location of the SMCS, this failure rate could impede clinical workflow.

Conclusion:

BPE shielding was shown to not reduce the average failure of the SMCS and relocation of the system outside of the accelerator vault was required to lower the failure rate enough to avoid impeding clinical work flow.
SU‐E‐T‐496: A Study of Two Commercial Dose Calculation Algorithms in Low Density Phantom
Authors: Lim S , Lovelock D , Yorke E , Kuo L , LoSasso T
Published: July 2014

Purpose:

Some lung cancer patients have very low lung density due to comorbidities. We investigate calculation accuracy of Eclipse AAA and Acuros(AXB) using a phantom that simulates this situation.

Methods:

A 2.5 x 5.0 x 5 cm (long) solid water inhomogeneity positioned 10 cm deep in a Balsa lung phantom (density 0.099 gm/cc) was irradiated with an off‐center field such that the central axis was parallel to one side of the inhomogeneity. Radiochromic films were placed at 2.5cm(S1) and 5cm(S2) depths. After CT scanning, Hounsfield Units(HU) were converted to electron(ρe) and mass(ρm) density using in‐house(IH) and vendor‐supplied(V) calibration curves. IH electron densities were generated using a commercial electron density phantom. The phantom was exposed to 6 MV 3×3 and 20×20 fields. Dose distributions were calculated using the AAA and AXB algorithms.

Results:

The HU of BW is ‐910±40 which translates to ρe of 0.088±0.050(IH) and 0.090±0.050(V), and ρm of 0.101±0.045(IH) and 0.103±0.039(V). Both ρe(V) and ρm(V) are higher than ρe(IH) and ρm(IH) respectively by 1.4‐5.3% and 0.5‐12.3%. The average calculated dose inside the solid water ‘tumor’ are within 3.7% and 2.4% of measurements for both calibrations and field sizes using AAA and AXB. Within 10mm outside the ‘tumor’, AAA on average underestimates by 18.3% and 17.0% respectively for 3×3 using IH and V. AXB underestimates by 5.9%(S1)‐6.6%(S2) and 13.1%(S1)‐16.0%(S2) respectively using IH and V. For 20×20, AAA and AXB underestimate by 2.8%(S1)‐4.4%(S2) and 0.3%(S1)‐1.4%(S2) respectively with either calibration.

Conclusion:

The difference in the HU calibration between V and IH is not of clinical significance in normal field sizes. In the low density region of small fields, the calculations from both algorithms differ significantly from measurements. This may be attributed to the insufficient lateral electron transport modeled by two algorithms resulting in the over‐estimation in penumbra expansion.
SU‐E‐T‐497: Semi‐Automated in Vivo Radiochromic Film Dosimetry Using a Novel Image Processing Algorithm
Authors: Reyhan M , Yue N
Published: July 2014

Purpose:

To validate an automated image processing algorithm designed to detect the center of radiochromic film used for in vivo film dosimetry against the current gold standard of manual selection.

Methods:

An image processing algorithm was developed to automatically select the region of interest (ROI) in *.tiff images that contain multiple pieces of radiochromic film (0.5×1.3cm2). After a user has linked a calibration file to the processing algorithm and selected a *.tiff file for processing, an ROI is automatically detected for all films by a combination of thresholding and erosion, which removes edges and any additional markings for orientation. Calibration is applied to the mean pixel values from the ROIs and a *.tiff image is output displaying the original image with an overlay of the ROIs and the measured doses. Validation of the algorithm was determined by comparing in vivo dose determined using the current gold standard (manually drawn ROIs) versus automated ROIs for n=420 scanned films. Bland‐Altman analysis, paired t‐test, and linear regression were performed to demonstrate agreement between the processes.

Results:

The measured doses ranged from 0.2‐886.6cGy. Bland‐Altman analysis of the two techniques (automatic minus manual) revealed a bias of ‐0.28cGy and a 95% confidence interval of (5.5cGy,‐6.1cGy). These values demonstrate excellent agreement between the two techniques. Paired t‐test results showed no statistical differences between the two techniques, p=0.98. Linear regression with a forced zero intercept demonstrated that Automatic=0.997*Manual, with a Pearson correlation coefficient of 0.999. The minimal differences between the two techniques may be explained by the fact that the hand drawn ROIs were not identical to the automatically selected ones. The average processing time was 6.7seconds in Matlab on an IntelCore2Duo processor.

Conclusion:

An automated image processing algorithm has been developed and validated, which will help minimize user interaction and processing time of radiochromic film used for in vivo dosimetry.
SU‐E‐T‐509: Validation of the Use of OSLD for Carbon Beam Remote Dosimetry
Authors: Summers P , Lowenstein J , Jakel O , Prokesch H , Alvarez P , Followill D
Published: July 2014

Purpose:

To describe the commissioning of Aluminum Oxide Optically Stimulated Luminescent Dosimeters (OSLD) for the use in Carbon beam remote dosimetry for centers participating in NCI‐funded cooperative group clinical trials.

Methods:

As Carbon therapy centers express interest in participating in cooperative group clinical trials, the Imaging and Radiation Oncology Core Group (IROC) Houston QA Center (formerly RPC) is developing a way to remotely monitor the machine output of these Carbon facilities. OSLD have been commissioned for photon, electron and proton dosimetry, so an experiment was designed to commission the same dosimeters for Carbon. OSLD were irradiated in a Carbon therapy beam produced by the Siemens synchrotron at the Heidelberg Ion Therapy facility in Heidelberg, Germany. The OSLD were placed in acrylic phantoms, imaged with a CT scanner, and plans were developed using the Siemens treatment planning system. The OSLD were irradiated in uniform fields with maximum energies of 216, 301, and 402 MeV and at dose levels of 50, 100, 200 and 300 cGy.

Results:

The response of the OSLD in the Carbon beam, as compared to the Cobalt‐60 reference condition, required an energy correction of 1.85 to account for the particle correction. OSLD dose calculations typically have a linearity correction to account for the change in response relative to the change in dose delivered. However, the response of the OSLD in the Carbon beam was found to be independent of the dose level; thus the linearity correction is 1.00.

Conclusion:

IROC Houston has commissioned OSLD for the use of remote output checks for Carbon therapy facilities to help ensure consistency across clinical trial participants.

Work supported by grant CA10953 (NCI, DHHS).
SU‐E‐T‐510: Mathematical Analysis of Approximate Biological Effective Dose (BED) Calculation for Multi‐Phase Radiotherapy Treatment Plans
Authors: Kauweloa K , Gutierrez A , Bergamo A , Stathakis S , Papanikolaou N , Mavroidis P
Published: July 2014

Purpose:

There is growing interest about biological effective dose (BED) and its application in treatment plan evaluation due to its stronger correlation with treatment outcome. An approximate biological effective dose (BEDA) equation was introduced to simplify BED calculations by treatment planning systems in multi‐phase treatments. The purpose of this work is to reveal its mathematical properties relative to the true, multi‐phase BED (BEDT) equation.

Methods:

The BEDT equation was derived and used to reveal the mathematical properties of BEDA. MATLAB (MathWorks, Natick, MA) was used to simulate and analyze common and extreme clinical multi‐phase cases. In those cases, percent error (Perror) and Bland‐Altman analysis were used to study the significance of the inaccuracies of BEDA for different combinations of total doses, numbers of fractions, doses per fractions and α over β values. All the calculations were performed on a voxel‐basis in order to study how dose distributions would affect the accuracy of BEDA.

Results:

When the voxel dose‐per‐fractions (DPF) delivered by both phases are equal, BEDA and BEDT are equal. In heterogeneous dose distributions, which significantly vary between the phases, there are fewer occurrences of equal DPFs and hence the imprecision of BEDA is greater. It was shown that as the α over β ratio increased the accuracy of BEDA would improve. Examining twenty‐four cases, it was shown that the range of DPF ratios for a 3 Perror varied from 0.32 to 7.50Gy, whereas for Perror of 1 the range varied from 0.50 to 2.96Gy.

Conclusion:

The DPF between the different phases should be equal in order to render BEDA accurate. OARs typically receive heterogeneous dose distributions hence the probability of equal DPFs is low. Consequently, the BEDA equation should only be used for targets or OARs that receive uniform or very similar dose distributions by the different treatment phases.
SU‐E‐T‐520: Four‐Dimensional Dose Calculation Algorithm Considering Variations in Dose Distribution Induced by Sinusoidal One‐Dimensional Motion Patterns
Authors: Taguenang J , Algan O , Ahmad S , Ali I
Published: July 2014

Purpose:

To investigate quantitatively the variations in dose‐distributions induced by motion by measurements and modeling. A four‐dimensional (4D) motion model of dose distributions that accounts for different motion parameters was developed.

Methods:

Variations in dose distributions induced by sinusoidal phantom motion were measured using a multiple‐diode‐array‐detector (MapCheck2). MapCheck2 was mounted on a mobile platform that moves with adjustable calibrated motion patterns in the superior‐inferior direction. Various plans including open and intensity‐modulated fields were used to irradiate MapCheck2. A motion model was developed to predict spatial and temporal variations in the dose‐distributions and dependence on the motion parameters using pencil‐beam spread‐out superposition function. This model used the superposition of pencil‐beams weighted with a probability function extracted from the motion trajectory. The model was verified with measured dose‐distributions obtained from MapCheck2.

Results:

Dose‐distribution varied considerably with motion where in the regions between isocenter and 50% isodose‐line, dose decreased with increase of the motion amplitude. Dose levels increased with increase in the motion amplitude in the region beyond 50% isodose‐line. When the range of motion (ROM=twice amplitude) was smaller than the field length both central axis dose and the 50% isodose‐line did not change with variation of motion amplitude and remained equal to the dose of stationary phantom. As ROM became larger than the field length, the dose level decreased at central axis dose and 50% isodose‐line. Motion frequency and phase did not affect the dose distributions which were delivered over an extended time longer than few motion cycles, however, they played an important role for doses delivered with high‐dose‐rates within one motion cycle .

Conclusion:

A 4D‐dose motion model was developed to predict and correct variations in dose distributions induced by one‐dimensional sinusoidal motion. This model was verified with measured dose‐distributions and can be expanded to consider complicated patient motion patterns.
SU‐E‐T‐529: Study of Second Cancer Risk in the Treatment of Multiple Lung Lesion by SBRT Using Rapid Arc: Comparison Between Different Treatment Planning Parameters
Authors: Sakthivel V , Ganesh K , Mani S , Boopathy R
Published: July 2014

Purpose:

To compare the secondary cancer risk (SCR) between different plan settings (Collimator angle, number of Arcs and manual jaw opening) for Rapid Arc plan in the treatment of multiple lung lesion.

Methods:

Patient with multiple lung lesion was planned with single isocenter (i) single arc (CW:200‐160deg) and (ii) dual complementary arc. The plans were optimized to yield similar plan evaluation/acceptance criteria. The concept of equivalent OED (linear‐exponential, plateau, and the linear dose– response model) was used to evaluate the Second Cancer Risk (SCR). Then, the single arc plan was generated using five different collimator setting (0,30,45,90,120 deg) and the OED was analyzed. Also, plans were generated with automatic jaw setting and compared against the manual jaw setting.

Results:

The SCR values were normalized to the single arc plan. For dual complementary arc, the relative SCR for Rt.lung were (linear, plateau, linear‐exponential) (1.02,1.05,1.04), (0.99,1.02,1.02) for Lt.lung, (1.01,1.07,1.06) for Spinal cord, (1.18,1.1,1.09) for Esophagus, (1.3,1.19,1.16) for Heart, (1,1.01,1.02) for Lt.Breast and (1.05,1.05,1.05) for Rt.Breast. Since the single arc plan was superior in terms of SCR further analysis was carried out for various collimator angles. The low dose bath volumes 5Gy in cc for single and dual arc plans were 5468 and 5886 cc respectively. The computed OED values (linear‐exponential) for Rt.Lung were (1,0.94,0.96,1.06,0.97), (1,0.89,0.97,1.11,0.9) for Lt.Lung, (1,0.86,0.98,1.2,0.92) for Spinal cord, (1,0.87,0.99,1.15,0.91) for esophagus, (1,0.88,1.01,1.11,0.94) for heart, (1,0.83,0.97,1.20,0.86) for lt.breast and (1,0.94,0.95,1.03,1.11) for Rt.breast for collimator setting (0,30,45,90,120 deg) respectively.

Conclusion:

The Second cancer risk is considerably high for dual arc plan compared with single arc. In single arc plan the 30 degree collimator angle plan showed the least OED values for all critical structures, with the 90 degree collimator angle being the most. No significant difference between the manual and the automatic jaw setting plans were found.
Gauging the Quality of Qualitative Research in Adapted Physical Activity
Authors: Zitomer Michelle R. , Goodwin Donna
Published: July 2014

Qualitative inquiry is increasingly being used in adapted physical activity research, which raises questions about how to best evaluate its quality. This article aims to clarify the distinction between quality criteria (the what) and strategies (the how) in qualitative inquiry. An electronic keyword search was used to identify articles pertaining to quality evaluation published between 1995 and 2012 (n = 204). A five phase systematic review resulted in the identification of 56 articles for detailed review. Data extraction tables were generated and analyzed for commonalities in terminology and meanings. Six flexible criteria for gauging quality were formulated: reflexivity, credibility, resonance, significant contribution, ethics, and coherence. Strategies for achieving the established criteria were also identified. It is suggested that researchers indicate the paradigm under which they are working and guidelines by which they would like readers to evaluate their work as well as what criteria can be absent without affecting the research value.
Methodology Review: Using Dual-Energy X-Ray Absorptiometry (DXA) for the Assessment of Body Composition in Athletes and Active People
Authors: Nana Alisa , Slater Gary J. , Stewart Arthur D. , Burke Louise M.
Published: July 2014

Dual energy X-ray absorptiometry (DXA) is rapidly becoming more accessible and popular as a technique to monitor body composition, especially in athletic populations. Although studies in sedentary populations have investigated the validity of DXA assessment of body composition, few studies have examined the issues of reliability in athletic populations and most studies which involve DXA measurements of body composition provide little information on their scanning protocols. This review presents a summary of the sources of error and variability in the measurement of body composition by DXA, and develops a theoretical model of best practice to standardize the conduct and analysis of a DXA scan. Components of this protocol include standardization of subject presentation (subjects rested, overnight-fasted and in minimal clothing) and positioning on the scanning bed (centrally aligned in a standard position using custom-made positioning aids) as well as manipulation of the automatic segmentation of regional areas of the scan results. Body composition assessment implemented with such protocol ensures a high level of precision, while still being practical in an athletic setting. This ensures that any small changes in body composition are confidently detected and correctly interpreted. The reporting requirements for studies involving DXA scans of body composition include details of the DXA machine and software, subject presentation and positioning protocols, and analysis protocols.
Errors in Dual Energy X-Ray Absorptiometry Estimation of Body Composition Induced by Hypohydration
Authors: Rodriguez-Sanchez Nidia , Galloway Stuart D.R.
Published: July 2014

Dual energy x-ray absorptiometry (DXA) is a popular tool to determine body composition (BC) in athletes, and is used for analysis of fat-free soft tissue mass (FFST) or fat mass (FM) gain/loss in response to exercise or nutritional interventions. The aim of the current study was to assess the effect of exercise-heat stress induced hypohydration (HYP, >2% of body mass (BM) loss) vs. maintenance of euhydration (EUH) on DXA estimates of BC, sum of skinfolds (SF), and impedance (IMP) measurements in athletes. Competitive athletes (23 males and 15 females) recorded morning nude BM for 7 days before the first main trial. Measurements on the first trial day were conducted in a EUH condition, and again after exercise-heat stress induced HYP. On the second trial day, fluid and electrolyte losses were replaced during exercise using a sports drink. A reduction in total BM (1.6 ± 0.4 kg; 2.3 ± 0.4% HYP) and total FFST (1.3 ± 0.4 kg), mainly from trunk (1.1 ± 0.5 kg), was observed using DXA when participants were HYP, reflecting the sweat loss. Estimated fat percent increased (0.3 ± 0.3%), however, total FM did not change (0.1 ± 0.2 kg). SF and IMP declined with HYP (losses of 1.5 ± 2.9% and 1.6 ± 3% respectively) suggesting FM loss. When EUH was maintained there were no significant changes in BM, DXA estimates, or SF values pre to post exercise, but IMP still declined. We conclude that use of DXA for FFST assessment in athletes must ensure a EUH state, particularly when considering changes associated with nutritional or exercise interventions.
Dietary Glutamine Supplementation Partly Reverses Impaired Macrophage Function Resulting From Overload Training in Rats
Authors: Xiao Weihua , Chen Peijie , Dong Jingmei , Wang Ru , Luo Beibei
Published: July 2014

The aim of this study was to evaluate the effect of overload training on the function of peritoneal macrophages in rats, and to test the hypothesis that glutamine in vivo supplementation would partly reverse the eventual functional alterations induced by overload training in these cells. Forty male Wistar rats were randomly divided into 5 groups: control group (C), overload training group (E1), overload training and restore one week group (E2), glutamine-supplementation group (EG1), and glutamine-supplementation and restore 1-week group (EG2). All rats, except those placed on sedentary control were subjected to 11 weeks of overload training protocol. Blood hemoglobin, serum testosterone, and corticosterone of rats were measured. Moreover, the functions (chemotaxis, phagocytosis, cytokines synthesis, reactive oxygen species generation) of peritoneal macrophages were determined. Data showed that blood hemoglobin, serum testosterone, corticosterone and body weight in the overload training group decreased significantly as compared with the control group. Meanwhile, the chemotaxis capacity (decreased by 31%, p = .003), the phagocytosis capacity (decreased by 27%, p = .005), the reactive oxygen species (ROS) generation (decreased by 35%, p = .003) and the cytokines response capability of macrophages were inhibited by overload training. However, the hindering of phagocytosis and the cytokines response capability of macrophages induced by overload training could be ameliorated and reversed respectively, by dietary glutamine supplementation. These results suggest that overload training impairs the function of peritoneal macrophages, which is essential for the microbicidal actions of macrophages. This may represent a novel mechanism of immunodepression induced by overload training. Nonetheless, dietary glutamine supplementation could partly reverse the impaired macrophage function resulting from overload training.
A Phenomenological Investigation of the Psychology of Big-Wave Surfing at Maverick’s
Authors: Wiersma Lenny D.
Published: July 2014

Extreme sport athletes perform in environments that are characterized by danger, unpredictability, and fear, and the consequences of a mistake include severe injury or death. Maverick’s is a big-wave surfing location in northern California that is known for its cold water temperatures, dangerous ocean wildlife, deep reef, and other navigational hazards. The purpose of this study was to use a phenomenological framework to understand the psychology of big-wave surfing at Maverick’s. Seven elite big-wave surfers completed in-depth phenomenological interviews and discussed the psychology related to various stages of big-wave surfing, including presurf, in the lineup, catching the wave, riding the wave, wiping out, and postsurf. Big-wave surfers described a variety of experiences associated with surfing at Maverick’s and discussed several ways that they coped with its challenges. The results provide a greater understanding of the psychology of participating in an extreme environment.
Toward an Understanding of Optimal Development Environments Within Elite English Soccer Academies
Authors: Mills Andrew , Butt Joanne , Maynard Ian , Harwood Chris
Published: July 2014

This study examined the factors perceived by successful coaches to underpin optimal development environments within elite English soccer academies. A semistructured interview guide was developed to interview 10 expert coaches about the environments they create for players at a key stage in their development. The interviews were transcribed verbatim and inductively content analyzed. The results identified a wide range of factors resulting in a conceptual framework that explained how these factors interact to underpin an optimal environment. Subcomponents of this framework included organizational core (e.g., advocate a player-driven ideology), adaptability (e.g., embrace novel ideas & approaches), player welfare (e.g., understand players’ world-view), key stakeholder relationships (e.g., build trust with parents), involvement (e.g., encourage players’ ideas/feedback), and achievement oriented (e.g., establish an explicit pathway to senior level). Collectively, the findings highlight the importance of establishing strong, dynamic, organizational cultures at elite youth soccer academies. Ways that academies might be helped to establish such environments are discussed.
Consulting on Tour: A Dual-Phase Personal-Disclosure Mutual-Sharing Intervention and Group Functioning in Elite Youth Cricket
Authors: Barker Jamie B. , Evans Andrew L. , Coffee Pete , Slater Matt J. , McCarthy Paul J.
Published: July 2014

In a one group pretest-posttest design, 15 elite academy cricketers were exposed to two personal-disclosure mutual-sharing (PDMS) sessions during a preseason tour. Within PDMS1, athletes disclosed (via prepared speeches) relationship-oriented information and within PDMS2, mastery oriented information. Social identity, social identity content, and collective efficacy were measured at baseline (1 week before the tour), post-PDMS1, midpoint, and post-PDMS2, while social validation was also obtained after each intervention session. Quantitative data revealed significant increases in social identity and friendships identity content at post-PDMS1, and results identity content and collective efficacy at post-PDMS2. Qualitative social validation data highlighted the thoughts and feelings of the athletes before their speeches and supported the effectiveness of the PDMS sessions. In sum, the data suggest practitioners can develop team outcomes (e.g., a focus on results) through developing specific aspects of teams’ identities. Study limitations, practitioner guidelines, and areas for future research are discussed.