bluuebunny/crossref_metadata_2025_split huggingface dataset:
Poster ‐ 36: Effect of Planning Target Volume Coverage on the Dose Delivered in Lung Radiotherapy
Authors: Dekker Chris , Wierzbicki Marcin 
Published: August 2016

Purpose:In lung radiotherapy, breathing motion may be encompassed by contouring the internal target volume (ITV). Remaining uncertainties are included in a geometrical expansion to the planning target volume (PTV). In IMRT, the treatment is then optimized until a desired PTV fraction is covered by the appropriate dose. The resulting beams often carry high fluence in the PTV margin to overcome low lung density and to generate steep dose gradients. During treatment, the high density tumour can enter the PTV margin, potentially increasing target dose. Thus, planning lung IMRT with a reduced PTV dose may still achieve the desired ITV dose during treatment.Methods:A retrospective analysis was carried out with 25 IMRT plans prescribed to 63 Gy in 30 fractions. The plans were re‐normalized to cover various fractions of the PTV by different isodose lines. For each case, the isocentre was moved using 125 shifts derived from all 3D combinations of 0 mm, (PTV margin ‐ 1 mm), and PTV margin. After each shift, the dose was recomputed to approximate the delivered dose.Results and Conclusion:Our plans typically cover 95% of the PTV by 95% of the dose. Reducing the PTV covered to 94% did not significantly reduce the delivered ITV doses for (PTV margin ‐ 1 mm) shifts. Target doses were reduced significantly for all other shifts and planning goals studied. Thus, a reduced planning goal will likely deliver the desired target dose as long as the ITV rarely enters the last mm of the PTV margin.
Poster – 41: External marker block placement on the breast or chest wall for left‐sided deep inspiration breath‐hold radiotherapy
Authors: Conroy Leigh , Guebert Alexandra , Smith Wendy 
Published: August 2016

Purpose:We investigate DIBH breast radiotherapy using the Real‐time Position Management (RPM) system with the marker‐block placed on the target breast or chest wall.Methods:We measured surface dose for three different RPM marker‐blocks using EBT3 Gafchromic film at 0° and 30° incidence. A registration study was performed to determine the breast surface position that best correlates with overall internal chest wall position. Surface and chest wall contours from MV images of the medial tangent field were extracted for 15 patients. Surface contours were divided into three potential marker‐block positions on the breast: Superior, Middle, and Inferior. Translational registration was used to align the partial contours to the first‐fraction contour. Each resultant transformation matrix was applied to the chest wall contour, and the minimum distance between the reference chest wall contour and the transformed chest wall contour was evaluated for each pixel.Results:The measured surface dose for the 2‐dot, 6‐dot, and 4‐dot marker‐blocks at 0° incidence were 74%, 71%, and 77% of dose to dmax respectively. At 30° beam incidence this increased to 76%, 72%, and 81%. The best external surface position was patient and fraction dependent, with no consistent best choice.Conclusions:The increase in surface dose directly under the RPM block is approximately equivalent to 3 mm of bolus. No marker‐block position on the breast surface was found to be more representative of overall chest wall motion; therefore block positional stability and reproducibility can be used to determine optimal placement on the breast or chest wall.
Poster ‐ 43: Analysis of SBRT and SRS dose verification results using the Octavius 1000SRS detector
Authors: Cherpak Amanda 
Published: August 2016

Purpose:The Octavius 1000SRS detector was commissioned in December 2014 and is used routinely for verification of all SRS and SBRT plans. Results of verifications were analyzed to assess trends and limitations of the device and planning methods.Methods:Plans were delivered using a True Beam STx and results were evaluated using gamma analysis (95%, 3%/3mm) and absolute dose difference (5%). Verification results were analyzed based on several plan parameters including tumour volume, degree of modulation and prescribed dose.Results:During a 12 month period, a total of 124 patient plans were verified using the Octavius detector. Thirteen plans failed the gamma criteria, while 7 plans failed based on the absolute dose difference. When binned according to degree of modulation, a significant correlation was found between MU/cGy and both mean dose difference (r=0.78, p<0.05) and gamma (r=−0.60, p<0.05). When data was binned according to tumour volume, the standard deviation of average gamma dropped from 2.2% – 3.7% for the volumes less than 30 cm3 to below 1% for volumes greater than 30 cm3.Conclusions:The majority of plans and verification failures involved tumour volumes smaller than 30 cm3. This was expected due to the nature of disease treated with SBRT and SRS techniques and did not increase rate of failure. Correlations found with MU/cGy indicate that as modulation increased, results deteriorated but not beyond the previously set thresholds.
Poster ‐ 48: Clinical assessment of ExacTrac stereoscopic imaging of spine alignment for lung SBRT
Authors: Sattarivand Mike , Summers Clare , Robar James 
Published: August 2016

Purpose:To evaluate the validity of using spine as a surrogate for tumor positioning with ExacTrac stereoscopic imaging in lung stereotactic body radiation therapy (SBRT).Methods:Using the Novalis ExacTrac x‐ray system, 39 lung SBRT patients (182 treatments) were aligned before treatment with 6 degrees (6D) of freedom couch (3 translations, 3 rotations) based on spine matching on stereoscopic images. The couch was shifted to treatment isocenter and pre‐treatment CBCT was performed based on a soft tissue match around tumor volume. The CBCT data were used to measure residual errors following ExacTrac alignment. The thresholds for re‐aligning the patients based on CBCT were 3mm shift or 3° rotation (in any 6D). In order to evaluate the effect of tumor location on residual errors, correlations between tumor distance from spine and individual residual errors were calculated.Results:Residual errors were up to 0.5±2.4mm. Using 3mm/3° thresholds, 80/182 (44%) of the treatments required re‐alignment based on CBCT soft tissue matching following ExacTrac spine alignment. Most mismatches were in sup‐inf, ant‐post, and roll directions which had larger standard deviations. No correlation was found between tumor distance from spine and individual residual errors.Conclusion:ExacTrac stereoscopic imaging offers a quick pre‐treatment patient alignment. However, bone matching based on spine is not reliable for aligning lung SBRT patients who require soft tissue image registration from CBCT. Spine can be a poor surrogate for lung SBRT patient alignment even for proximal tumor volumes.
Poster ‐ 53: Improving inter‐linac DMLC IMRT dose precision by fine tuning of MLC leaf calibration
Authors: Nakonechny Keith , Tran Muoi , Sasaki David , Beck James , Poirier Yannick , Malkoske Kyle 
Published: August 2016

Purpose:To develop a method to improve the inter‐linac precision of DMLC IMRT dosimetry.Methods:The distance between opposing MLC leaf banks (“gap size”) can be finely tuned on Varian linacs. The dosimetric effect due to small deviations from the nominal gap size (“gap error”) was studied by introducing known errors for several DMLC sliding gap sizes, and for clinical plans based on the TG119 test cases. The plans were delivered on a single Varian linac and the relationship between gap error and the corresponding change in dose was measured. The plans were also delivered on eight Varian 2100 series linacs (at two institutions) in order to quantify the inter‐linac variation in dose before and after fine tuning the MLC calibration.Results:The measured dose differences for each field agreed well with the predictions of LoSasso et al. Using the default MLC calibration, the variation in the physical MLC gap size was determined to be less than 0.4 mm between all linacs studied. The dose difference between the linacs with the largest and smallest physical gap was up to 5.4% (spinal cord region of the head and neck TG119 test case). This difference was reduced to 2.5% after fine tuning the MLC gap calibration.Conclusions:The inter‐linac dose precision for DMLC IMRT on Varian linacs can be improved using a simple modification of the MLC calibration procedure that involves fine adjustment of the nominal gap size.
Poster ‐ 55: Active Breathing Coordinator Based Treatment of Liver SBRT Patients
Authors: Karotki Aliaksandr , Erler Darby , Chu William , Chung Hans T. 
Published: August 2016

Purpose:Accuracy of treatment delivery for liver SBRT patients can be compromised by breathing induced motion. Recently we started using active breathing coordinator (ABC) to “freeze” the breathing motion. This work describes our initial experience with ABC based treatment of liver SBRT patients.Methods:Patients are treated in maximum exhale state with a minimum required breath hold time of 20 s. Fluoroscopy is used to assess diaphragm stability before both simulation and treatment. Depending on the proximity of organs at risk, 30–60 Gy are given in five fractions every other day and delivered via VMAT. CBCT is used for patient setup verification with robotic couch compensating for translations/rotations. An additional CBCT is acquired after every fraction to confirm patient's stability during treatment.Results:Six patients have successfully been treated using the ABC protocol so far with an approximate treatment time of 1 h. CBCT acquired after the treatment suggests that patients are stable and the liver position, when locked by ABC, is reproducible throughout the treatment (average deviation 1.9 mm). The major immediate benefit of using ABC is a drastic improvement in image quality of the CT simulation as well as CBCT images.Conclusions:ABC eliminates breathing motion and, as such, substantially improves the quality of the images acquired at CT simulation as well as CBCT images leading to more reliable dose delivery. The position of the liver remains stable for the duration of treatment when using the ABC system. The treatment is well tolerated by the patients.
Sci‐Fri PM: Radiation Therapy, Planning, Imaging, and Special Techniques ‐ 02: Feasibility of using multileaf collimation for stereotactic radiosurgery of arteriovenous malformation
Authors: Lee Young , Tsao May , Schwartz Michael , Ruschin Mark 
Published: August 2016

SRS using linac and cones offers steep dose fall‐off but a tradeoff exists between conformality and treatment time, which depends on the number of isocentres. Purpose of this study is to quantify planning metrics between cones‐ and MLC‐based SRS for arteriovenous malformation(AVM).Seven AVM cases treated with cones were re‐planned with MLC on Pinnacle treatment planning system. Planning target volume(PTV) was created with 1mm uniform margin to the AVM to account for MLC positional variation. Clinically‐planned prescription dose(15–25Gy) was used. Four plans were generated per case:non‐coplanar VMAT(ncV), single‐arc VMAT(saV), non‐coplanar IMRT(ncI), non‐coplanar conformal(ncC). Plans were compared for conformity(CI), heterogeneity(HI) and gradient(GI) indices and brain doses. Estimated treatment times and monitor units(MU) were compared.Cone‐based plans required 2–6 isocentres. Though CI‐RTOG was similar for plans(median=0.98), CI‐Paddick was most favourable for ncV(median=0.86) and worst for cones(0.54). HI for MLC plans(median=1.19–1.27) were lower than cone‐based plans(1.43). GI was similar for all plans. For 2/7 ncC had brainstem maximum dose>16.7Gy and therefore were clinically unacceptable. Brain V12Gy,V10Gy,V2Gy were lowest in the cones plan. ncV brain V12Gy,V10Gy,V2Gy were lowest of all MLC‐based plans studied. Treatment MUs were similar for MLC‐based plans and up to 70% lower than clinically delivered plans.ncV showed best conformality in this study. Of the MLC‐based plans, ncV also showed lowest normal tissue dose with reasonable treatment time.
Sci‐Fri PM: Radiation Therapy, Planning, Imaging, and Special Techniques ‐ 06: Patient‐specific QA Procedure for Gated VMAT SABR Treatments using 10x Beam in Flattening‐Filter Free Mode
Authors: Mestrovic Ante , Chitsazzadeh Shadi , Wells Derek M. , Gray Stephen 
Published: August 2016

Purpose:To develop a highly sensitive patient specific QA procedure for gated VMAT stereotactic ablative radiotherapy (SABR) treatments.Methods:A platform was constructed to attach the translational stage of a Quasar respiratory motion phantom to a pinpoint ion chamber insert and move the ion chamber inside the ArcCheck. The Quasar phantom controller uses a patient‐specific breathing pattern to translate the ion chamber in a superior‐inferior direction inside the ArcCheck. With this system the ion chamber is used to QA the correct phase of the gated delivery and the ArcCheck diodes are used to QA the overall dose distribution. This novel approach requires a single plan delivery for a complete QA of a gated plan. The sensitivity of the gating QA procedure was investigated with respect to the following parameters: PTV size, exhale duration, baseline drift, gating window size.Results:The difference between the measured dose to a point in the penumbra and the Eclipse calculated dose was under 2% for small residual motions. The QA procedure was independent of PTV size and duration of exhale. Baseline drift and gating window size, however, significantly affected the penumbral dose measurement, with differences of up to 30% compared to Eclipse.Conclusion:This study described a highly sensitive QA procedure for gated VMAT SABR treatments. The QA outcome was dependent on the gating window size and baseline drift. Analysis of additional patient breathing patterns is currently undergoing to determine a clinically relevant gating window size and an appropriate tolerance level for this procedure.
Evaluation of Two Enzyme-Linked Immunosorbent Assay Kits for Chikungunya Virus IgM Using Samples from Deceased Organ and Tissue Donors
Authors: Prince Harry E. , Altrich Michelle L. , Nowicki Marek J. 
Published: August 2016

ABSTRACT
The identification of nearly 3,500 cases of chikungunya virus (CHIKV) infection in U.S. residents returning in 2014 and 2015 from areas in which it is endemic has raised concerns within the transplant community that, should recently infected individuals become organ and/or tissue donors, CHIKV would be transmitted to transplant recipients. Thus, tests designed to detect recent CHIKV infection among U.S. organ and tissue donors may become necessary in the future. Accordingly, we evaluated 2 enzyme-linked immunosorbent assays (ELISAs) for CHIKV IgM readily available in the United States using 1,000 deidentified serum or plasma specimens collected from donors between November 2014 and March 2015. The Euroimmun indirect ELISA identified 38 reactive specimens; however, all 38 were negative for CHIKV IgG and IgM in immunofluorescence assays (IFAs) conducted at a reference laboratory and, thus, were falsely reactive in the Euroimmun CHIKV IgM assay. The InBios IgM-capture ELISA identified 26 reactive samples, and one was still reactive (index ≥ 1.00) when retested using the InBios kit with a background subtraction modification to identify false reactivity. This reactive specimen was CHIKV IgM negative but IgG positive by IFAs at two reference laboratories; plaque reduction neutralization testing (PRNT) demonstrated CHIKV-specific reactivity. The IgG and PRNT findings strongly suggest that the InBios CHIKV IgM-reactive result represents true reactivity, even though the IgM IFA result was negative. If testing organ/tissue donors for CHIKV IgM becomes necessary, the limitations of the currently available CHIKV IgM ELISAs and options for their optimization must be understood to avoid organ/tissue wastage due to falsely reactive results.
Differential Detection of Human Papillomavirus Genotypes and Cervical Intraepithelial Neoplasia by Four Commercial Assays
Authors: Rebolj Matejka , Bonde Jesper , Preisler Sarah , Ejegod Ditte , Rygaard Carsten , Lynge Elsebeth 
Published: August 2016

ABSTRACT

Laboratories now can choose from >100 human papillomavirus (HPV) assays for cervical screening. Our previous analysis based on the data from the Danish Horizon study, however, showed that four widely used assays, Hybrid Capture 2 (HC2), cobas, CLART, and Aptima, frequently do not detect the same HPV infections. Here, we determined the characteristics of the concordant samples (all four assays returning a positive HPV test result) and discordant samples (all other HPV-positive samples) in primary cervical screening at 30 to 65 years of age (
n
= 2,859) and in a concurrent referral population from the same catchment area (
n
= 885). HPV testing followed the manufacturers' protocols. Women with abnormal cytology were managed according to the routine recommendations. Cytology-normal/HPV-positive women were invited for repeated testing in 18 months. Screening history and histologically confirmed cervical intraepithelial neoplasia (CIN) in 2.5 years after the baseline testing were determined from the national pathology register. HPV-positive women undergoing primary screening having concordant samples were more likely to harbor high-risk infections and less likely to harbor only low-risk infections than women with discordant samples. Additionally, assay signal strengths were substantially higher in concordant samples. More than 80% of ≥CIN2 results were found for women with concordant samples, and no ≥CIN2 results were found when the infection was detected by only one assay. These patterns were similar in the referral population despite the younger age and higher number of HPV infections. HPV test result discordance identified a cluster of low-risk HPV infections that were hardly ever associated with high-grade CIN and, almost exclusively, represented false-positive screening findings.
Zipper junctions: A new approach to the intersections of conjugate strike-slip faults
Authors: Platt John P. , Passchier Cees W. 
Published: August 2016

Abstract
Intersecting pairs of simultaneously active faults with opposing slip sense present geometrical and kinematic problems. Such faults rarely offset each other but usually merge into a single fault, even when they have displacements of many kilometers. The space problems involved are solved by lengthening the merged fault (zippering up the conjugate faults) or splitting it (unzippering). This process can operate in thrust, normal, and strike-slip fault settings. Examples of conjugate pairs of large-scale strike-slip faults that may have zippered up include the Garlock and San Andreas faults in California (USA), the North and East Anatolian faults (Turkey), the Karakoram and Altyn Tagh faults (Tibet), and the Tonale and Giudicarie faults (southern Alps). Intersecting conjugate ductile shear zones behave in the same way on outcrop and micro-scales. Zippering may produce complex and significant patterns of strain and rotation in the surrounding rocks, depending on the angle between the faults and the relative strength of the blocks they bound. A zippered fault will have a slip rate equal to the vector sum of the slip rates on the merging faults, unless that displacement is transferred into or out of the system by distributed strain in the surrounding rocks.
Recycling in debris-filled volcanic vents
Authors: Graettinger A.H. , Valentine G.A. , Sonder I. 
Published: August 2016

Abstract
Eruptions through debris-filled vents produce deposits containing magmatic juvenile lithic and recycled clasts. Recycled clasts are exposed to multiple transportation and fragmentation events. We used experiments with multiple subsurface explosions to track clasts and highlight dominant recycling processes in eruptions through analog debris-filled vents. Recycled clasts include those that fall back into and reside in the vent for extended time periods and those that return to the vent through crater growth or collapse. Clasts are recycled by any combination of lofting and fallback of material in the crater by explosion jets, mixing and churning of material at depth in the debris fill, and redistribution of extra-crater deposits by explosion-induced excavation or slumping. We compare experimental processes with natural deposits that preserve recycling signatures from discrete explosions through debris-filled vents such as maar-diatremes, Strombolian vents, and hydrothermal craters. Clasts may not preserve textures diagnostic of their complete recycling histories, but can be used to infer if that history occurred in part in the vent debris or in the eruptive jet. Experiment results and natural deposits suggest that for volcanic craters that undergo multiple explosions, clasts likely undergo some form of recycling before final deposition outside the craters. The underestimation of recycled clast contributions to deposits can lead to inaccurate estimates of thermal budgets and eruption processes.
A REVIEW OF THE USE OF CALCIUM LIQUID VERSUS CALCIUM TABLETS FOR MAINTAINING CORRECTED CALCIUM LEVELS
Authors: Semple Diarmaid , Howlett Moninne 
Published: August 2016

AimSince the discontinuation of a commercially available liquid calcium medicine, there have been various local strategies to obtain adequate calcium levels, particularly in suspected 22Q11.2 deletion syndrome children post cardiothoracic surgery. Pharmacy obtained on special order a Calcium Liquid food supplement (0.5 mmol calcium/ml) for use in those children whom effervescent tablets did not appear to improve corrected calcium. Anecdotally it was thought that calcium liquid was better tolerated and absorbed, resulting in quicker recovery time of corrected calcium than use of the effervescent tablets. This review of patients was intended to determine if the use of the liquid was associated with a significant improvement in calcium levels compared to the use of tablets.MethodA dispense report was undertaken to identify those patients supplied with the calcium liquid product from May 2014 to May 2015.Using the electronic prescribing system, the patients electronic health record was accessed, and the following information recorded; calcium, albumin, intake calcium in fluids, TPN, oral and Intravenous. The data was collected for seven days previous to the first administration of calcium liquid and seven days after where available. Corrected calcium was calculated using an accepted method (calcium=serum calcium+0.02* (normal albumin – patient albumin)).ResultsNine children supplied with calcium liquid between May 2014 and May 2015. Four patients who did not have histories on the electronic prescribing system were excluded for ease of analysis. The electronic medication record of the five remaining patients was used to compare calcium intake from all sources including fluids and feed.As expected calcium levels (and corrected calcium level where relevant) did improve when calcium liquid was added in. However four of the patients received calcium from multiple sources. Of these three received more calcium (mmol/kg/day) in fluids and feeds than from the administered pharmacy product.One single patient did not receive calcium from any other sources (fluids/TPN/feed). However there did not appear to be a significant change in calcium levels when calcium liquid was introduced as opposed to calcium tablets.ConclusionAlthough based on a small number of patients, from this experience it would not seem that the calcium liquid obtained by pharmacy results in higher calcium serum levels.Further analysis may be required to distinguish the effects from calcium intake in feed/fluid and calcium intake from medicines.