bluuebunny/crossref_metadata_2025 huggingface dataset:
Strong arm tactics: sexual dimorphism in macropodid limb proportions
Authors: Richards H. L. , Grueter C. C. , Milne N.
Published: June 2015

Macropodid (kangaroo and wallaby) males use their forelimbs as weaponry in fights for dominance and access to females. The choreography and intensity of these fights varies with species body size. It has been established that the largest species show stronger dimorphism in upper limb muscularity as a product of sexual selection via increased intermale competition. However, beyond muscularity, and across the other macropodid species, limb dimorphism is poorly understood. Here, we examine dimorphism in the relative proportions of the bones within the forelimb and between the fore‐ and hindlimbs. We used a large sample of bones from 15 promiscuous macropodid species to confirm that absolute dimorphism in the forelimb becomes greater with body size (indexed by cranial length), and to further explore whether dimorphism in relative forelimb proportions increases also. As macropodids are obligate bipedal hoppers, no dimorphism was expected in the lower limb. Phylogenetic generalized least‐square regression was used to resolve phylogenetic non‐independence of the data. Greater upper limb dimorphism was significantly correlated with longer crania, confirming established patterns, but we found it was the relative length of the male humerus that became increasingly exaggerated with species' body size, not the radius as previously suggested. Enlarged proximal limb segments are indicative of adaptations for powerful movements. This aligns with higher intensity and ritualization of male agonistic behaviour, and reflects an increased selection for strong male forelimbs in the larger promiscuous species. Contrary to our hypothesis, relative male pes length decreased with body size, possibly indicating selection for a stronger and sturdier pes required for powerful kicks. This study clarifies the patterns of sexual dimorphism in Macropodidae limbs and illustrates the power of sexual selection to influence anatomy that is fundamental to locomotion in both sexes.
Customer‐Base Concentration and Inventory Efficiencies: Evidence from the Manufacturing Sector
Authors: Ak B. Korcan , Patatoukas Panos N.
Published: June 2015

What is the link between customer‐base concentration and inventory efficiencies in the manufacturing sector? Using hand‐collected data from 10‐K Filings, we find that manufacturers with more concentrated customer bases hold fewer inventories for less time and are less likely to end up with excess inventories, as indicated by the lower likelihood and magnitude of inventory write‐downs and reversals. Using disaggregated inventory disclosures, we find that inventory efficiencies primarily flow through the finished goods inventory account, while raw material efficiencies are offset by higher work‐in‐process holdings and longer work‐in‐process cycles. In additional analysis, we document a valuation premium for more concentrated manufacturers after controlling for other firm characteristics, including default risk and cost of capital estimates. We conclude that investors trade off the costs and benefits of relationships with a limited number of major customers and, on balance, consider customer‐base concentration as a net positive for firm valuation. Overall, our study adds to interdisciplinary research in accounting and operations management by shedding new light on the relevance of major customer disclosures for fundamental analysis and valuation in the manufacturing sector.
Passive restoration can be an effective strategy: a reply to Prach and del Moral (2015)
Authors: Zahawi Rakan A. , Reid J. Leighton , Holl Karen D.
Published: June 2015

We agree with Prach and del Moral that passive recovery is often a desirable and effective restoration strategy. Passive and various active restoration approaches need to be weighed on a case‐by‐case basis and depend on the goals, relative rates of recovery desired, and various social and financial costs implicit in each option. That said, we stress that passive restoration has a unique set of challenges and costs, which we highlighted in our original article and briefly reiterate here.
Textual and textile literacies in early modern braids
Authors: Canavan Claire
Published: June 2015

This article considers the handicraft of braiding, a variety of textile work in which loops of silk were placed on the fingers and interwoven to make strings containing patterns, motifs or alphabetic characters, usually formed into posies. The practice often involved the collaboration of multiple participants and is documented extensively in thirteen seventeenth‐century manuscripts, which present written directions, usually alongside worked examples. Largely overlooked in recent studies of women's handiwork, braiding and braids appear to have been pervasive in early modern culture: they are invoked directly and indirectly in a variety of contemporary texts which emphasize that they possessed social, cultural and political meaning. This article argues that braiding constitutes a complex model of expression and social production, which sets alphabetic content alongside the rich significance of form, pattern, material and collaborative bodily practice. Drawing out connections between braiding and varieties of poetic composition in a range of other writings, I emphasize that braids blur distinctions between textual and textile literacies and indicate a need to rethink the relationship of the needle and the pen.
Experimental Analysis of Water Vapor Diffusion Through Porous Membranes in a Proton Exchange Membrane Fuel Cell
Authors: Kumar Bansal Lalit , Deepu P. , Basu Saptarshi
Published: June 2015

We report the diffusion characteristics of water vapor through two different porous media, viz., membrane electrode assembly (MEA) and gas diffusion layer (GDL) in a nonoperational fuel cell. Tunable diode laser absorption spectroscopy (TDLAS) was employed for measuring water vapor concentration in the test channel. Effects of the membrane pore size and the inlet humidity on the water vapor transport are quantified through mass flux and diffusion coefficient. Water vapor transport rate is found to be higher for GDL than for MEA. The flexibility and wide range of application of TDLAS in a fuel cell setup is demonstrated through experiments with a stagnant flow field on the dry side.
Rewetting of Vertical Pipes by Bottom Flooding Using Nanofluid as a Coolant
Authors: Paul Gayatri , Das Prasanta Kumar , Manna Indranil
Published: June 2015

The present investigation reports the rewetting phenomenon by bottom flooding in vertical pipes using both water and nanofluid as coolant. The transient temperature response of rewetted surface indicates that rewetting takes place faster in nanofluids than in water. The effect of several parameters, including the coolant flow rate, distance from the inlet of fluid, concentration of nanoparticle loading on the rewetting characteristics, has been investigated. The rewetting velocity, for both water and nanofluid, is observed to depend strongly on the inlet coolant flow rate and initial wall temperature of the tube. The rewetting velocity is observed to follow the correlation for water proposed in an earlier work. Starting from the logic proposed in that previous report, the authors propose a correlation for predicting the rewetting velocity in nanofluids.
SU‐D‐207‐03: Development of 4D‐CBCT Imaging System with Dual Source KV X‐Ray Tubes
Authors: Nakamura M , Ishihara Y , Matsuo Y , Ueki N , Iizuka Y , Mizowaki T , Hiraoka M
Published: June 2015

Purpose:

The purposes of this work are to develop 4D‐CBCT imaging system with orthogonal dual source kV X‐ray tubes, and to determine the imaging doses from 4D‐CBCT scans.

Methods:

Dual source kV X‐ray tubes were used for the 4D‐CBCT imaging. The maximum CBCT field of view was 200 mm in diameter and 150 mm in length, and the imaging parameters were 110 kV, 160 mA and 5 ms. The rotational angle was 105°, the rotational speed of the gantry was 1.5°/s, the gantry rotation time was 70 s, and the image acquisition interval was 0.3°. The observed amplitude of infrared marker motion during respiration was used to sort each image into eight respiratory phase bins. The EGSnrc/BEAMnrc and EGSnrc/DOSXYZnrc packages were used to simulate kV X‐ray dose distributions of 4D‐CBCT imaging. The kV X‐ray dose distributions were calculated for 9 lung cancer patients based on the planning CT images with dose calculation grid size of 2.5 × 2.5 × 2.5 mm. The dose covering a 2‐cc volume of skin (D2cc), defined as the inner 5 mm of the skin surface with the exception of bone structure, was assessed.

Results:

A moving object was well identified on 4D‐CBCT images in a phantom study. Given a gantry rotational angle of 105° and the configuration of kV X‐ray imaging subsystems, both kV X‐ray fields overlapped at a part of skin surface. The D2cc for the 4D‐CBCT scans was in the range 73.8–105.4 mGy. Linear correlation coefficient between the 1000 minus averaged SSD during CBCT scanning and D2cc was −0.65 (with a slope of −0.17) for the 4D‐CBCT scans.

Conclusion:

We have developed 4D‐CBCT imaging system with dual source kV X‐ray tubes. The total imaging dose with 4D‐CBCT scans was up to 105.4 mGy.
SU‐D‐207‐05: Real‐Time Intrafractional Motion Tracking During VMAT Delivery Using a Conventional Elekta CBCT System
Authors: Park Yang‐Kyun , Sharp Gregory C. , Gierga David P. , Ye Sung‐Joon , Winey Brian A.
Published: June 2015

Purpose:

Real‐time kV projection streaming capability has become recently available for Elekta XVI version 5.0. This study aims to investigate the feasibility and accuracy of real‐time fiducial marker tracking during CBCT acquisition with or without simultaneous VMAT delivery using a conventional Elekta linear accelerator.

Methods:

A client computer was connected to an on‐board kV imaging system computer, and receives and processes projection images immediately after image acquisition. In‐house marker tracking software based on FFT normalized cross‐correlation was developed and installed in the client computer. Three gold fiducial markers with 3 mm length were implanted in a pelvis‐shaped phantom with 36 cm width. The phantom was placed on a programmable motion platform oscillating in anterior‐posterior and superior‐inferior directions simultaneously. The marker motion was tracked in real‐time for (1) a kV‐only CBCT scan with treatment beam off and (2) a kV CBCT scan during a 6‐MV VMAT delivery. The exposure parameters per projection were 120 kVp and 1.6 mAs. Tracking accuracy was assessed by comparing superior‐inferior positions between the programmed and tracked trajectories.

Results:

The projection images were successfully transferred to the client computer at a frequency of about 5 Hz. In the kV‐only scan, highly accurate marker tracking was achieved over the entire range of cone‐beam projection angles (detection rate / tracking error were 100.0% / 0.6±0.5 mm). In the kV‐VMAT scan, MV‐scatter degraded image quality, particularly for lateral projections passing through the thickest part of the phantom (kV source angle ranging 70°‐110° and 250°‐290°), resulting in a reduced detection rate (90.5%). If the lateral projections are excluded, tracking performance was comparable to the kV‐only case (detection rate / tracking error were 100.0% / 0.8±0.5 mm).

Conclusion:

Our phantom study demonstrated a promising Result for real‐time motion tracking using a conventional Elekta linear accelerator. MV‐scatter suppression is needed to improve tracking accuracy during MV delivery.

This research is funded by Motion Management Research Grant from Elekta.
SU‐D‐207‐07: Implementation of Full/half Bowtie Filter Model in a Commercial Treatment Planning System for Kilovoltage X‐Ray Imaging Dose Estimation
Authors: Kim S , Alaei P
Published: June 2015

Purpose:

To implement full/half bowtie filter models in a commercial treatment planning system (TPS) to calculate kilovoltage (kV) x‐ray imaging dose of Varian On‐Board Imager (OBI) cone beam CT (CBCT) system.

Methods:

Full/half bowtie filters of Varian OBI were created as compensator models in Pinnacle TPS (version 9.6) using Matlab software (version 2011a). The profiles of both bowtie filters were acquired from the manufacturer, imported into the Matlab system and hard coded in binary file format. A Pinnacle script was written to import each bowtie filter data into a Pinnacle treatment plan as a compensator. A kV x‐ray beam model without including the compensator model was commissioned per each bowtie filter setting based on percent depth dose and lateral profile data acquired from Monte Carlo simulations. To validate the bowtie filter models, a rectangular water phantom was generated in the planning system and an anterior/posterior beam with each bowtie filter was created. Using the Pinnacle script, each bowtie filter compensator was added to the treatment plan. Lateral profile at the depth of 3cm and percent depth dose were measured using an ion chamber and compared with the data extracted from the treatment plans.

Results:

The kV x‐ray beams for both full and half bowtie filter have been modeled in a commercial TPS. The difference of lateral and depth dose profiles between dose calculations and ion chamber measurements were within 6%.

Conclusion:

Both full/half bowtie filter models provide reasonable results in kV x‐ray dose calculations in the water phantom. This study demonstrates the possibility of using a model‐based treatment planning system to calculate the kV imaging dose for both full and half bowtie filter modes. Further study is to be performed to evaluate the models in clinical situations.
SU‐D‐201‐02: Prediction of Delivered Dose Based On a Joint Histogram of CT and FDG PET Images
Authors: Park M , Choi Y , Cho A , Hwang S , Cha J , Lee N , Yun M
Published: June 2015

Purpose:

To investigate whether pre‐treatment images can be used in predicting microsphere distribution in tumors. When intra‐arterial radioembolization using Y90 microspheres was performed, the microspheres were often delivered non‐uniformly within the tumor, which could lead to an inefficient therapy. Therefore, it is important to estimate the distribution of microspheres.

Methods:

Early arterial phase CT and FDG PET images were acquired for patients with primary liver cancer prior to radioembolization (RE) using Y90 microspheres. Tumor volume was delineated on CT images and fused with FDG PET images. From each voxel (3.9×3.9×3.3 mm3) in the tumor, the Hounsfield unit (HU) from the CT and SUV values from the FDG PET were harvested. We binned both HU and SUV into 11 bins and then calculated a normalized joint‐histogram in an 11×11 array.Patients also underwent a post‐treatment Y90 PET imaging. Radiation dose for the tumor was estimated using convolution of the Y90 distribution with a dose‐point kernel. We also calculated a fraction of the tumor volume that received a radiation dose great than 100Gy.

Results:

Averaged over 40 patients, 55% of tumor volume received a dose greater than 100Gy (range : 1.1 – 100%). The width of the joint histogram was narrower for patients with a high dose. For patients with a low dose, the width was wider and a larger fraction of tumor volume had low HU.

Conclusion:

We have shown the pattern of joint histogram of the HU and SUV depends on delivered dose. The patterns can predict the efficacy of uniform intra‐arterial delivery of Y90 microspheres.
SU‐D‐210‐02: A New Phantom Design for Routine Doppler Ultrasound Testing
Authors: Grice J , Pickens D , Price R
Published: June 2015

Purpose:

The objective of this project is to develop a simple, inexpensive, and highly portable Doppler ultrasound quality assurance phantom for routine testing. A prototype phantom has been designed and fabricated. It is powered by gravity alone, requires no external equipment for operation, and produces a stable fluid velocity useful for quality assurance. In contrast, currently available Doppler testing systems are large, expensive, and require external power. The new phantom aims to remedy these problems while still offering satisfactory capability of routine quality testing.

Methods:

The current system measures 15.9cmx10.8cmx12.7cm, is sealed, and contains about 55 ml of Doppler test fluid. Two reservoirs for the Doppler fluid to flow between were designed and then printed on a 3D printer. The printed components were connected with latex tubing and then seated in a tissue‐mimicking gel. Data to confirm reproducibility was acquired on an Acuson Sequoia 512 ultrasound system (Siemens Medical Solutions).

Results:

The current system maintains stable flow from one reservoir to the other for approximately 7 seconds. Color Doppler imaging has shown to be qualitatively consistent with laminar flow. Using Pulsed Doppler, average velocities from the current system have been measured at 0.178 m/s with a standard deviation of 0.021 m/s across 102 measurements.

Conclusion:

Due largely to unavailability of an appropriate phantom, Doppler ultrasound often lacks frequent quality testing. This system attempts to address several obstacles facing Doppler testing, which may make weekly, and even daily Doppler testing feasible in clinical settings. The future goals of this project will be to further refine the system and measurement techniques to achieve more stable measurements and longer periods of flow. There are still several degrees of freedom in the system (transducer location, fluid temperature, tube radius, etc.) that have yet to be optimized and should increase the reproducibility of the system.
SU‐D‐210‐03: Limited‐View Multi‐Source Quantitative Photoacoustic Tomography
Authors: Feng J , Gao H
Published: June 2015

Purpose:

This work is to investigate a novel limited‐view multi‐source acquisition scheme for the direct and simultaneous reconstruction of optical coefficients in quantitative photoacoustic tomography (QPAT), which has potentially improved signal‐to‐noise ratio and reduced data acquisition time.

Methods:

Conventional QPAT is often considered in two steps: first to reconstruct the initial acoustic pressure from the full‐view ultrasonic data after each optical illumination, and then to quantitatively reconstruct optical coefficients (e.g., absorption and scattering coefficients) from the initial acoustic pressure, using multi‐source or multi‐wavelength scheme.Based on a novel limited‐view multi‐source scheme here, We have to consider the direct reconstruction of optical coefficients from the ultrasonic data, since the initial acoustic pressure can no longer be reconstructed as an intermediate variable due to the incomplete acoustic data in the proposed limited‐view scheme. In this work, based on a coupled photo‐acoustic forward model combining diffusion approximation and wave equation, we develop a limited‐memory Quasi‐Newton method (LBFGS) for image reconstruction that utilizes the adjoint forward problem for fast computation of gradients. Furthermore, the tensor framelet sparsity is utilized to improve the image reconstruction which is solved by Alternative Direction Method of Multipliers (ADMM).

Results:

The simulation was performed on a modified Shepp‐Logan phantom to validate the feasibility of the proposed limited‐view scheme and its corresponding image reconstruction algorithms.

Conclusion:

A limited‐view multi‐source QPAT scheme is proposed, i.e., the partial‐view acoustic data acquisition accompanying each optical illumination, and then the simultaneous rotations of both optical sources and ultrasonic detectors for next optical illumination. Moreover, LBFGS and ADMM algorithms are developed for the direct reconstruction of optical coefficients from the acoustic data.

Jing Feng and Hao Gao were partially supported by the NSFC (#11405105), the 973 Program (#2015CB856000) and the Shanghai Pujiang Talent Program (#14PJ1404500).
SU‐D‐210‐07: The Dependence On Acoustic Velocity of Medium On the Needle Template and Electronic Grid Alignment in Ultrasound QA for Prostate Brachytherapy
Authors: Kapoor P , Kapoor R , Curran B
Published: June 2015

Purpose:

To analyze the impact on acoustic velocity (AV) of two different media (water and milk) using the needle template/electronic grid alignment test. Water, easily available, makes a good material to test the alignment of the template and grid although water's AV (1498 m/s at 25°C) is significantly different from tissue (1540 m/s). Milk, with an AV much closer (1548 m/s) to prostate tissue, may be a good substitute for water in ultrasound quality assurance testing.

Methods:

Tests were performed using a Hitachi ultrasound unit with a mechanical arrangement designed to position needles parallel to the transducer. In this work, two materials – distilled water and homogenized whole milk (AVs of 1498 and 1548 m/s at 25°C) were used in a phantom to test ultrasound needle/grid alignment. The images were obtained with both materials and analyzed for their placement accuracy.

Results:

The needle template/electronic grid alignment tests showed displacement errors between measured and calculated values. The measurements showed displacements of 2.3mm (water) and 0.4mm (milk), and 1.6mm (water) and 0.3mm (milk) at depths of 7cm and 5cm respectively from true needle positions. The calculated results showed a displacement of 2.36 mm (water); 0.435mm (milk), and 1.66mm (water) and 0.31mm (milk) at a depth of 7cm and 5cm respectively. The displacements in the X and Y directions were also calculated. At depths of 7cm and 5cm, the (ΔX,ΔY) displacements in water were (0.829mm, 2.21mm) and (0.273mm, 1.634mm) and for milk were (0.15mm, 0.44mm) and (0.05mm, 0.302mm) respectively.

Conclusion:

The measured and calculated values were in good agreement for all tests. They show that milk provides superior results when performing needle template and electronic grid alignment tests for ultrasound units used in prostate brachytherapy.
SU‐E‐E‐12: Validation of the Implementation of Different CT Scanners in Proton Treatment Planning
Authors: Fuentes C Llina , Geismer D , Christiaens M , Vermeren X , Ding X
Published: June 2015

Purpose:

To quantify the impact of the relationship of CT number and Relative Stopping Power (RSP) among different CT‐scanners in the evaluation of dose distribution, for different tumor sites and proton therapy modalities like Pencil Beam and Uniform Scanning.

Methods:

The same tissue characterization phantom was used to analyze the difference in the X‐rays energy spectra of 2 CT scanners of the same vendor. One CT is for planning and the other for treatment verification. The Hounsfield unit (HU) variations and associated dosimetric uncertainty were investigated in uniform scanning and pencil beam treatment plans of different sites. At the same time comparisons of the CT calibration curve were done using the same acquisition protocols. The phantom was imaged on a 16 multi‐row CT scanner, with energies of 120 and 140 kVp,currents of 263 and 245 mA and slice thickness of 2 and 3mm respectively. The dosimetric uncertainty of the plans was evaluated in a homogeneus phantom comparing DVHs, gamma index criteria 3% 3mm, and range between them.

Results:

The variation of HU was within the standard deviation of the average for each tissue substitute. The curves fitted with a bilinear interpolation show a maximum deviation in high density materials like cortical bone and solid water, where the HU values deviated more than 0,6% for the 120kVp protocol. For the others curves the deviation was more than 2% for low densities materials. The gamma index uncertainty criteria passed in all the cases.

Conclusion:

The HU variations for the different scanners were ≤3%. Lower than the 3,5% uncertainties considered in our treatment planning system. The dosimetric analysis shows that the X‐ray spectrum has a small effect on the HU‐RSP curve, allowing the use of a single tissue characterization curve in our proton treatment planning system for plans verifications.
SU‐E‐P‐08: Establishment of Local Diagnostic Reference Levels of Routine Abdomen Exam in Computed Tomography According to Body Weight
Authors: Wang H , Wang Y , Weng H
Published: June 2015

Purpose:

The national diagnostic reference levels (NDRLs) is an efficient, concise and powerful standard for optimizing radiation protection of a patient. However, for each hospital the dose‐reducing potential of focusing on establishment of local DRLs (LDRLs). A lot of study reported that Computed tomography exam contributed majority radiation dose in different medical modalities, therefore, routine abdomen CT exam was choose in initial pilot study in our study. Besides the mAs of routine abdomen CT exam was decided automatic exposure control by linear attenuation is relate to body shape of patient. In this study we would like to establish the local diagnostic reference levels of routine abdomen exam in computed tomography according to body weight of patient.

Methods and Materials:

There are two clinical CT scanners (a Toshiba Aquilion and a Siemens Sensation) were performed in this study. For CT examinations the basic recommended dosimetric quantity is the Computed Tomography Dose Index (CTDI). The patient sample involved 82 adult patients of both sexes and divided into three groups by their body weight (50–60 kg, 60–70 kg, 70–80 kg).Carried out the routine abdomen examinations, and all exposure parameters have been collected and the corresponding CTDIv and DLP values have been determined. The average values were compared with the European DRLs.

Results:

The majority of patients (75%) were between 50–70 Kg of body weight, the numbers of patient in each group of weight were 40–50:7; 50–60:29; 60–70:33; 70–80:13. The LDRLs in each group were 10.81mGy, 14.46mGy, 20.27mGy and 21.04mGy, respectively. The DLP were 477mGy, 630mGy, 887mGy and 959mGy, respectively. No matter which group the LDRLs were lower than European DRLs.

Conclusions:

We would like to state that this was a pioneer work in local hospital in Chiayi. We hope that this may lead the way to further developments in Taiwan
SU‐E‐P‐10: Establishment of Local Diagnostic Reference Levels of Routine Exam in Computed Tomography
Authors: Yeh M , Wang Y , Weng H
Published: June 2015

Introduction National diagnostic reference levels (NDRLs) can be used as a reference dose of radiological examination can provide radiation dose as the basis of patient dose optimization. Local diagnostic reference levels (LDRLs) by periodically view and check doses, more efficiency to improve the way of examination. Therefore, the important first step is establishing a diagnostic reference level. Computed Tomography in Taiwan had been built up the radiation dose limit value,in addition, many studies report shows that CT scan contributed most of the radiation dose in different medical. Therefore, this study was mainly to let everyone understand DRL's international status. For computed tomography in our hospital to establish diagnostic reference levels. Methods and Materials: There are two clinical CT scanners (a Toshiba Aquilion and a Siemens Sensation) were performed in this study. For CT examinations the basic recommended dosimetric quantity is the Computed Tomography Dose Index (CTDI). Each exam each different body part, we collect 10 patients at least. Carried out the routine examinations, and all exposure parameters have been collected and the corresponding CTDIv and DLP values have been determined.

Results:

The majority of patients (75%) were between 60–70 Kg of body weight. There are 25 examinations in this study. Table 1 shows the LDRL of each CT routine examination.

Conclusions:

Therefore, this study would like to let everyone know DRL's international status, but also establishment of computed tomography of the local reference levels for our hospital, and providing radiation reference, as a basis for optimizing patient dose.
SU‐E‐P‐12: Pinnacle‐Based Tool to Evaluate the Effect of Prostate Rotation as Determined by Calypso
Authors: Narayanan S , Velasco‐Schmitz R , Claeys K , Cho P
Published: June 2015

Purpose:

When the Calypso reports a large prostate rotation and one does not have the means to make corrections, it is helpful to quantify its dosimetric effects. We have devised a simple scheme to achieve this in Pinnacle TPS. If it is determined that the PTV margin is inadequate, an alternate larger‐margin plan may be adapted for the day.

Methods:

A three‐step process using the Pinnacle Image fusion module was formulated to analyze the clinical effect of prostate rotation. The process includes (1) translating the image set such that the rotational axis is about the isocenter, (2) performing 3D rotations of the structures of interest, and (3) restoring the coordinates associated with the plan. The rotated structures are imported and overlayed on the original plan for evaluation. The tool was applied to three prostate cancer patients with relatively large rotations (95 fractions total). Prostate rotations are primarily due to variations in bladder and rectal filling, which may also affect the seminal vesicles. It is difficult to estimate the perturbation of seminal vesicles for a given prostate rotation. Therefore, the Calypso‐derived rotation matrix was applied only to CTV and PTV (CTV+5mm).

Results:

The rotations were predominantly in the pitch direction with an absolute value ranging from 0–29 degrees (Median = 10°, Average = 14.5°). For various magnitudes of rotation, the CTV V100 decreased from the original 100% to 99.6%/99%/95% for 10°/15°/29° rotations, respectively. Likewise, the PTV V100 diminished from 95% to 92%/89%/82%.

Conclusion:

A tool, consisting only of features within a TPS, was used to evaluate the dosimetric effect of prostate rotation. Our study shows that under large uncorrected rotations, the tumor coverage is degraded and may require intervention in the form of plan adaptation. To this end, alternate plans with variable margins can be generated in advance for daily adaption.
SU‐E‐P‐14: Dosimetric Effects of Magnetic Field in MRI‐Guided Radiation Therapy Delivery for Breast Cancer
Authors: Chen G , Currey A , Li X
Published: June 2015

Purpose:

MRI‐guided radiation therapy (RT) delivery would be beneficial for breast irradiation. The electron return effect due to the presence of a transverse magnetic field (TMF) may cause dosimetric issues on dose on skin and at the lung‐tissue interface. The purpose of this study is to investigate these issues.

Methods:

IMRT plans with tangential beams and VMAT plans with 200 degree arcs to cover ipsilateral breast were generated for 10 randomly selected breast cancer cases using a research planning system (Monaco, Elekta) utilizing Monte Carlo dose calculation with or without a TMF of 1.5 T. Plans were optimized to deliver uniform dose to the whole breast with an exclusion of 5 mm tissue under the skin (PTV‐EVAL). All four plans for each patient were re‐scaled to have the same PTV‐EVAL volume to receive the same prescription dose. The skin is defined as the first 5 mm of ipsilateral‐breast tissue, plus extensions in the surrounding region.

Results:

The presence of 1.5 T TMF resulted in (1)increased skin dose, with the mean and maximum skin dose increase of 5% and 9%, respectively; (2) similar dose homogeneity within the PTV‐EVAL; (3) the slightly improved (3%) dose homogeneity in the whole breast; (4) Averages of 9 and 16% increases in V5 and V20, respectively, for ipsilateral lung; and (5) increased the mean heart dose by 34%. VMAT plans don't improve whole breast dose uniformity as compared that to the tangential plans.

Conclusion:

The presence of transverse magnetic field in MRI‐guided RT delivery for whole breast irradiation can Result in slightly improved dose homogeneity in the whole breast, increased dose to the ipsilateral lung, heart, and skin. Plan optimization with additional specific dose volume constraints may eliminate/reduce these dose increases.

This work is partially supported by Elekta Inc.
SU‐E‐P‐22: AAPM Task Group 263 Tackling Standardization of Nomenclature for Radiation Therapy
Authors: Matuszak M , Moran J , Xiao Y , Mayo C , Bosch W , Popple R , Marks L , Wu Q , Molineu A , Miller R , Yock T , McNutt T , Brown N , Purdie T , Yorke E , Santanam L , Gabriel P , Michalski J , Moore J , Richardson S , Siochi R , Napalitano M , Ulin K , Fitzgerald T , Feng M , Verbakel W , Siddiqui S , Morgas T , Martel M , Archambault Y , Ladra M , Lansing B , Ruo R , Fogliata‐Cozzi A , Hurkmans C
Published: June 2015

Purpose:

There is growing recognition of need for increased clarity and consistency in the nomenclatures used for body and organ structures, DVH metrics, toxicity, dose and volume units, etc. Standardization has multiple benefits; e.g. facilitating data collection for clinical trials, enabling the pooling of data between institutions, making transfers (i.e. hand‐offs) between centers safer, and enabling vendors to define “default” settings. Towards this goal, the American Association of Physicists in Medicine (AAPM) formed a task group (TG263) in July of 2014, operating under the Work Group on Clinical Trials to develop consensus statements. Guiding principles derived from the investigation and example nomenclatures will be presented for public feedback.

Methods:

We formed a multi‐institutional and multi‐vendor collaborative group of 39 physicists, physicians and others involved in clinical use and electronic transfer of information. Members include individuals from IROC, NRG, IHE‐RO, DICOM WG‐7, ASTRO and EORTC groups with overlapping interests to maximize the quality of the consensus and increase the likelihood of adoption. Surveys of group and NRG members were used to define current nomenclatures and requirements. Technical requirements of vendor systems and the proposed DICOM standards were examined.

Results:

There is a marked degree of inter and intra institutional variation in current approaches, resulting from inter‐vendor differences in capabilities, clinic specific conceptualizations and inconsistencies. Using a consensus approach, the group defined optimal formats for the naming of targets and normal structures. A formal objective assessment of 13 existing clinically‐used software packages show that all had capabilities to accommodate these recommended nomenclatures.

Conclusions:

A multi‐stakeholder effort is making significant steps forward in developing a standard nomenclature that will work across platforms. Our current working list includes > 550 structures. Outreach efforts are ongoing to ensure broader participation in evaluating and testing the principles as they are developed by TG263.
SU‐E‐P‐24: Simplified EDW Profile Measurements Using Two Commonly Available Detector Arrays
Authors: Reynolds T , Arentsen L , Watanabe Y , Alaei P
Published: June 2015

Purpose:

Enhanced dynamic wedge (EDW) profiles are needed as part of the commissioning of a treatment planning system. This work compares the acquisition of EDW profiles using a linear diode array (LDA) with two commonly used detector arrays available in the clinics, with the goal of identifying the simplest approach for these measurements.

Methods:

The measurements of EDW profiles were performed on a Varian TrueBeam linear accelerator for 6, 10, and 18 MV photon beams for all seven wedge angles at four depths. The measurements were done using the LDA 99 in Blue Phantom2 (IBA Dosimetry), and IC Profiler and MapCHECK2 (Sun Nuclear) in solid water phantoms. The water phantom was set up at 100 cm SSD, whereas the two other devices were set up at 75 cm due to the size limitations of the devices. The largest possible field size was used. The average and maximum percentage differences were examined within the central 90% of the field and in the penumbra.

Results:

Dose profiles measured with IC Profiler were in a good agreement with LDA 99 data. The average percentage difference within the field did not exceed 0.5% for all energies. MapCHECK2 measurements matched well with LDA 99 for 10 and 18 MV (within 0.3%) with discrepancies of up to 1.4% observed for the 6 MV beam. The maximum percentage differences for both devices in the penumbra exhibited larger variations than LDA 99 results due to differences in detector spacing and high dose gradient, as expected.

Conclusion:

Common linac QA devices such as IC Profiler or MapCHECK2 provide EDW beam profile data of reasonable accuracy as compared to measurements performed using a linear diode array in a water phantom, saving the expense and time involved in acquiring and setting up a LDA.
SU‐E‐P‐25: Evaluation of Motion in Pancreas SBRT Treatment Deliveries
Authors: Xiong L , Halvorsen P
Published: June 2015

Purpose:

Stereotactic Body Radiation Therapy (SBRT) procedures for pancreatic cancer present a challenge in motion management because the target is directly adjacent to critical structures and the target is subject to significant respiratory motion. Gated treatment is usually planned with a tight (few mm) PTV margin. The positioning and setup relies on on‐board‐imaging (OBI) of internal fiducials. This study evaluates the corrections for inter‐ and intra‐fractional target motion as evidenced by the OBI.

Methods:

20 patients with gated pancreas SBRT treatment were setup with KV imaging guidance before and during each treatment. The couch position was fine‐tuned to align with the internal fiducials for each patient. The data for 148 intra‐ and 111 inter‐fractional couch movements were captured and analyzed.

Results:

The mean ± standard deviation of couch shifts for the initial daily setup is 4.9±4.1 mm for couch vertical, 5.3±4.6 mm for couch longitudinal, and 3.7±4.0 mm for couch lateral. The mean ± standard deviation of intra‐treatment adjustments are 1.1±1.6, 2.5±3.8, and 1.1±1.8 mm for couch vertical, longitudinal and lateral. The probability of intra‐fractional motion in the three orthogonal directions with magnitude no more than 2 mm, 3 mm and 5 mm is 55%, 68% and 84% respectively.

Conclusion:

The intra‐treatment target motion for pancreas SBRT patients indicates that a PTV margin of 5mm may be necessary.
SU‐E‐P‐32: Adapting An MMLC to a Conventional Linac to Perform Stereotactic Applications
Authors: Emam I , Hosini M
Published: June 2015

Purpose:

Micro‐MLCs minimizes beam scalloping effects caused by conventional‐MLCs and facilitates conformal dynamic treatment delivery. But their effect on dosimetric parameters require careful investigations. Physical and dosimetric parameters and Linac mechanical stability with mMLC (net weight 30 Kg) attached to the gantry are to be investigated. Moreover, output study along with recommended jaws offsets are studied. Adaptation of an mMLC to our 16‐years old conventional Linac is investigated in this work

Methods:

BrainLab mMLC (m3) mounted in a detachable chassis to the Philips SL‐15 Linac (30kg). Gantry and collimator spoke shots measurements are made using a calibrated film in a solid phantom and compared with pin‐point measurements. Leaf penumbra, transmission, leakage between the leaves, percentage depth dose (PDD) are measured using IBA pin‐point ion chamber at 6 and 10 MV. For output measurements (using brass build‐up cap), jaws are modified continuously regarding to m3‐fields while output factor are compared with fixed jaws situation, while the mMLC leaf configuration is modified for different m3‐fields

Results:

Mean transmission through leaves is 1.9±0.1% and mean leakage between leaves is 2.8±0.15%. Between opposing leaves abutting along the central beam‐axis mean transmission is 15±3%, but it is reduced to 4.5±0.6% by moving the abutment position 4.5cm off‐axis. The penumbra was sharper for m3 ‐fields than jaws‐fields (maximum difference is 1.51±0.2%). m3‐fields PDD show ∼3% variation from those of jaws‐fields. m3‐fields output factors show large variations (<4%) from Jaws defined fields. Output for m3‐rectangular fields show slight variation in case of leaf‐end&leaf‐side as well as X‐jaw&Y‐jaw exchange. Circular m3‐fields output factors shows close agreement with their corresponding square jaws‐defined fields using 2mm Jaws offsets, If jaws are retracted to m3 limits, differences become <5%.

Conclusion:

BrainLab m3 is successfully adapted to our 16 old Philips‐SL‐15 Linac. Dosimetric properties should be taken into account for treatment planning considerations.
SU‐E‐P‐44: The Characteristics and Clinical Application of the ArcCHECK for VMAT Verification
Authors: Chengqiang L
Published: June 2015

Purpose:

To evaluate the characteristics and clinical suitability of the ArcCHECK QA system for VMAT verification.

Methods:

The intrinsic sensitivity,short and long term reproducibility,dose and dose rate dependence,dose per pulsed dependence,field sizes dependence and directional response of the diodes were measured.The results of the diodes were compared with the measurement results of an ionization chamber and calculated results of TPS. Gamma index (3mm distance to agreement and 3% percentage difference ) was used to analyze the dose difference between the calculation and measurement for random selected 211 verified VMAT plans.

Results:

The ArcCHECK diodes performed well for all tests except directional dependence, which varies from a minimum of −3.9% (seen only when the beam is incident on the diode at 180°) to a maximum of 7.7% (approximately at 255°). Average gamma analysis passing rates with 3mm/3% for 113 NPC,48 cervical cancer and 50 rectal cancer VMAT plans are 93.5%,95.7% and 97.5%, statistical significance has been found between either two of the groups(t=−12.69∼−4.88,all P<0.01).

Conclusion:

With proposed calibration method,the ArcCHECK QA system is very suitable for VMAT pretreatment verification,the complexity of VMAT plan is the main factor affecting the passing rate.
SU‐E‐P‐52: Dose‐Volume Toxicity Analysis of Stereotactic Body Radiation Therapy for Hepatocellular Carcinoma
Authors: Bergamo A , Kauweloa K , Daniels J , Crownover R , Mavroidis P , Papanikolaou N , Gutierrez A
Published: June 2015

Purpose:

To investigate the relationship between physical and biological effective dose (BED) to liver toxicity for SBRT fractionations.

Methods:

A total of 16 patients (13–10×3Gy, 2–5×10Gy and 1–3×15Gy were selected. Physical dose distributions were converted to voxel based BED values using the linear‐quadratic (LQ) and linear‐quadratic linear (LQ‐L) models for doses per fraction larger than 6Gy. Patients were graded for effective toxicity (post‐treatment minus pre‐treatment grades) using the RTOG Late Radiation Morbidity Scoring Schema associated with Radiation Induced Liver Disease (RILD). Evaluated physical dose‐volume levels consisted of V10Gy, V15Gy, V20Gy, V25Gy and V30Gy which were then converted to BED values corresponding to V16.7Gy3, V30Gy3, V46.7Gy3, V66.7Gy3 and V90Gy3, respectively. All levels were normalized to their respective patient normal liver volumes (NLV) and evaluated for correlation to RILD. Results were measured quantitatively using R‐squared regression analysis.

Results:

Mean Dose Tolerable to Normal Liver (MDTNL) against RILD grade resulted in an R‐squared value of 0.0104. NLV‐normalized physical dose linear regression fit of V10Gy, V15Gy, V20Gy, V25Gy and V30Gy against RILD yielded R‐squared values of 0.1041, 0.0895, 0.0698, 0.0398 and 0.0009 while BED levels of V16.7Gy3, V30Gy3, V46.7Gy3, V66.7Gy3 and V90Gy3 resulted in values of 0.0002, 0.0153, 0.0533, 0.0427 and 0.0072, respectively. The average NLV‐normalized V10Gy, V15Gy, V20Gy, V25Gy and V30Gy per grade plotted against RILD grade yielded R‐squared correlations of 0.8092, 0.6362, 0.5899, 0.5846 and 0.0224 while the BED levels of V16.7Gy3, V30Gy3, V46.7Gy3, V66.7Gy3 and V90Gy3 resulted in R‐squared correlations of 0.0003, 0.3831, 0.8476, 0.678 and 0.076, respectively.

Conclusion:

Regression analysis between physical dose, BED and RILD showed strong correlation for the V30Gy and V46.7Gy3 dose‐levels. Average BED and physical dose per grade both exhibit strong correlations to RILD however, a lack of statistical significance exists due to small patient sample size.
SU‐E‐P‐55: The Reaserch of Cervical Cancer Delivered with Constant Dose Rate and Gantry Speed Arc Therapy(CDR‐CAS‐IMAT) On Conventional Linac
Authors: Zhang R , Bai W , Gao Y , Chi Z , Gao C , Xiaomei F
Published: June 2015

Purpose:

Postoperative cervical cancer patients with large target volume and the target shape is concave, treatmented with static intensity‐modulated radiotherapy (IMRT) is time consuming. The purpose of this study is to investigate using constant dose rate and gantry speed arc therapy(CDR‐CAS‐IMAT) on conventional linear accelrator, by comparing with the IMRT technology to evaluate the performance of CDR‐CAS‐IMAT on postoperative cervical cancer patients.

Methods:

18 cervical cancer patients treated with IMRT on Varian 23IX were replanted using CDR‐CAS‐IMAT. The plans were generated on Oncentra v4.1 planning system, PTV was prescribed to 50.4 Gy in 28 fractions. Plans were evaluated based on the ability to meet the dose volume histogram. The homogeneity index (HI), conformity index (CI) of target volume, the dose of organs at risk, radiation delivery time and monitor units were also compared. SPSS 19.0 software paired T‐test analysis was carried out on the two sets of data.

Results:

Compared with the IMRT plans PTV's CI (t= 3.85, P =0.001), CTV's CI, HI, D90, D95, D98, V95, V98, V100 (t=4.21, −3.18, 2.13, 4.65, 7.79, 2.29, 6.00, 2.13, p=0.001, 0.005, 0.049, 0.000, 0.000, 0.035, 0.000, 0.049), and cord D2 and rectum V40 (t=−2.65, −2.47, p= P =0.017, 0.025), and treatment time and MU (t=−36.0, −6.26, P =0.000, 0.000) were better than that of IMRT group. But the IMRT plans in terms of decreasing bladder V50, bowel V30 (t=2.14, 3.00, P =0.048, 0.008) and low dose irradiation volume were superior to that of CDR‐CAS‐IMAT plans. There were no significant differences in other statistical index.

Conclusion:

Cervical cancer patients with CDR‐CAS‐IMAT on Varian Clinical 23IX can get equivalent or superior dose distribution compared with the IMRT technology. IMAT have much less treatment time and MU can reduce the uncertainty factor and patient discomfort in treatment.

This work was supported by the Medical Science Foundation of the health department of Hebei Province (No. 20130253)
SU‐E‐P‐56: Dosimetric Comparison of Three Post Modified Radical Mastectomy Radiotherapy Techniques for Locally Advanced Left‐Sided Breast Cancer and Beyond
Authors: Ma C , Zhang W , Lu J , Wu L , Wu F , Huang B , Li D
Published: June 2015

Purpose:

To compare the dosimetry of post modified radical mastectomy radiotherapy (PMRMRT) for left‐sided breast cancer using 3‐dimensional conformal radiotherapy (3DCRT), intensity‐modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT).

Methods:

We created ten sets of PMRMRT plans for ten consecutive patients and utilized two tangential and one or two supraclavicular beams in 3DCRT, a total of 5 beams in IMRT and two optimized partial arcs in VMAT. The difference in results between any two of the three new plans, between new and previous 3DCRT plans were compared and analyzed by ANOVA (α =0.05) and paired‐sample t‐test respectively. P values less than 0.05 were considered statistically significant.

Results:

Both IMRT and VMAT plans had similar PTV coverage, hotspot area and conformity (all p>0.05), and significantly higher PTV coverage compared with new 3DCRT (both p<0.001). IMRT plans had significantly less heart and left lung radiation exposure compared with VMAT (all p<0.05). The 3DCRT plans with larger estimated CTV displacement had better target coverage but worse OARs sparing compared to those with smaller one.

Conclusion:

IMRT has dosimetrical advantages over the other two techniques in PMRMRT for left‐sided breast cancer. Individually quantifying and minimizing CTV displacement can significantly improve dosage distribution.

This work was supported by the Medical Scientific Research Foundation of Guangdong Procvince (A2014455 to Changchun Ma)