bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of lens dose from anterior electron beams: comparison of Pinnacle and Gafchromic EBT3 film
Authors: Sonier Marcus , Wronski Matt , Yeboah Collins 
Published: February 2017

Lens dose is a concern during the treatment of facial lesions with anterior electron beams. Lead shielding is routinely employed to reduce lens dose and minimize late complications. The purpose of this work is twofold: 1) to measure dose profiles under large‐area lead shielding at the lens depth for clinical electron energies via film dosimetry; and 2) to assess the accuracy of the Pinnacle treatment planning system in calculating doses under lead shields. First, to simulate the clinical geometry, EBT3 film and 4 cm wide lead shields were incorporated into a Solid Water phantom. With the lead shield inside the phantom, the film was positioned at a depth of 0.7 cm below the lead, while a variable thickness of solid water, simulating bolus, was placed on top. This geometry was reproduced in Pinnacle to calculate dose profiles using the pencil beam electron algorithm. The measured and calculated dose profiles were normalized to the central‐axis dose maximum in a homogeneous phantom with no lead shielding. The resulting measured profiles, functions of bolus thickness and incident electron energy, can be used to estimate the lens dose under various clinical scenarios. These profiles showed a minimum lead margin of 0.5 cm beyond the lens boundary is required to shield the lens to of the dose maximum. Comparisons with Pinnacle showed a consistent overestimation of dose under the lead shield with discrepancies of occurring near the shield edge. This discrepancy was found to increase with electron energy and bolus thickness and decrease with distance from the lead edge. Thus, the Pinnacle electron algorithm is not recommended for estimating lens dose in this situation. The film measurements, however, allow for a reasonable estimate of lens dose from electron beams and for clinicians to assess the lead margin required to reduce the lens dose to an acceptable level.PACS number(s): 87.53.Bn, 87.53.Kn, 87.55.‐x, 87.55.D‐
Quantitative outcome of registration methods for correcting cardiac drift in cardiac PET/CT imaging
Authors: Nye Jonathon A. , Tudorascu Dana , Esteves Fabio , Votaw John R. 
Published: February 2017

Myocardial perfusion studies suffer from artifacts caused by misalignment of the transmission and emission data due to the influences of voluntary and involuntary patient motion. Regardless of or respiratory‐averaged CT based attenuation correction and good patient cooperation, approximately 21% of perfusion studies exhibit artifacts arising from misalignment that cannot be corrected by manipulating the attenuation acquisition protocol. This misalignment, termed cardiac drift, is caused by slow‐moving abdominal cavity contents that reposition the heart in the thorax and appear as myocardial uptake overlying the left CT lung in fused PET/CT images. This study evaluates three postimaging registration techniques to correct PET/CT misalignment by altering the transmission map to match myocardial uptake. Simulated misalignment studies were performed with a cardiac torso phantom filled with []FDG at 10:1 myocardium/background. An air‐filled saline bag affixed to the medial left lung surface served as a distensible lung. An initial CT acquisition was followed by successive PET acquisitions consisting of small displacements of the cardiac insert into the left lung. Phantom transmission scans were aligned to the myocardial uptake in the emission scans by applying 1) full rigid‐body translations and rotations, 2) rigid‐body restricted to medial / lateral and superior / inferior translation, or 3) an emission‐driven method that adds myocardial tissue to the transmission scan. These methods were also applied to 10 low‐likelihood coronary artery disease (CAD) patients showing signs of cardiac drift. Full rigid‐body registration showed significant over‐correction () of activity concentrations in the artifact areas of the phantom data due the relocation of highly attenuating structures (i.e., spine). Inaccurate regional activity distributions were also observed as streaks extending from the spine and these results were replicated in the patient population. There was no significant difference between the true phantom activity concentration after correction with the emission‐driven method. Misalignment corrected with the rigid‐body registration results in an increase in activity concentration but fails to accurately recover the true concentration. These data suggest that a nonlinear image registration approach such as an emission‐driven method results in a more uniform activity distribution throughout the myocardium, and is more appropriate for addressing the cardiac drift misalignment problem.PACS number(s): 87.57.uk, 87.57.Q, 87.57.nj, 87.57.C, 87.19.Hh
The suitability of common metrics for assessing parotid and larynx autosegmentation accuracy
Authors: Beasley William J. , McWilliam Alan , Aitkenhead Adam , Mackay Ranald I. , Rowbottom Carl G. 
Published: February 2017

Contouring structures in the head and neck is time‐consuming, and automatic segmentation is an important part of an adaptive radiotherapy workflow. Geometric accuracy of automatic segmentation algorithms has been widely reported, but there is no consensus as to which metrics provide clinically meaningful results. This study investigated whether geometric accuracy (as quantified by several commonly used metrics) was associated with dosimetric differences for the parotid and larynx, comparing automatically generated contours against manually drawn ground truth contours. This enabled the suitability of different commonly used metrics to be assessed for measuring automatic segmentation accuracy of the parotid and larynx. Parotid and larynx structures for 10 head and neck patients were outlined by five clinicians to create ground truth structures. An automatic segmentation algorithm was used to create automatically generated normal structures, which were then used to create volumetric‐modulated arc therapy plans. The mean doses to the automatically generated structures were compared with those of the corresponding ground truth structures, and the relative difference in mean dose was calculated for each structure. It was found that this difference did not correlate with the geometric accuracy provided by several metrics, notably the Dice similarity coefficient, which is a commonly used measure of spatial overlap. Surface‐based metrics provided stronger correlation and are, therefore, more suitable for assessing automatic segmentation of the parotid and larynx.PACS number(s): 87.57.nm, 87.55.D, 87.55.Qr
A pilot study of volumetric‐modulated arc therapy for malignant pleural mesothelioma
Authors: Runxiao Li , Yankun Cao , Lan Wang 
Published: February 2017

Malignant pleural mesothelioma (MPM) is an extremely difficult disease to treat. This pilot study investigates the feasibility of using volumetric‐modulated arc therapy (VMAT) for malignant pleural mesothelioma (MPM), and compares VMAT to static field intensity‐modulated radiotherapy (IMRT) for five patients. To identify the best treatment technique for MPM, in five patients, we made a representative comparative analysis of two kinds of techniques for radiation therapy planning: IMRT and VMAT. The plans were created for an Elekta Synergy linear accelerator with 6 MV photons using Oncentra version 4.3 treatment planning system. Dose prescription was 50 Gy to the average of the planning target volume (PTV). PTV coverage and homogeneity, dose of organs at risk, numbers of segments, MUs, and delivery time were evaluated for all techniques. VMAT allowed better homogeneous and conformity indices compared with IMRT ( vs. 0.12, vs. 0.77, respectively, ). VMAT plan had a significantly shorter delivery time (326 s) compared with in IMRT plans (510 s), (). In the dose verification, an average of 93.16% of the detector points passed the 3%/3 mmγ criterion for VMAT plans, while in IMRT plans the dose verification was 95.12%.().PACS number(s): 87.55.D, 87.55.km, 87.56.Fc
Practical considerations for noise power spectra estimation for clinical CT scanners
Authors: Dolly Steven , Chen Hsin‐Chen , Anastasio Mark , Mutic Sasa , Li Hua 
Published: February 2017

Local noise power spectra (NPS) have been commonly calculated to represent the noise properties of CT imaging systems, but their properties are significantly affected by the utilized calculation schemes. In this study, the effects of varied calculation parameters on the local NPS were analyzed, and practical suggestions were provided regarding the estimation of local NPS for clinical CT scanners. The uniformity module of a Catphan phantom was scanned with a Philips Brilliance 64 slice CT simulator with varied scanning protocols. Images were reconstructed using FBP and iDose4 iterative reconstruction with noise reduction levels 1, 3, and 6. Local NPS were calculated and compared for varied region of interest (ROI) locations and sizes, image background removal methods, and window functions. Additionally, with a predetermined NPS as a ground truth, local NPS calculation accuracy was compared for computer simulated ROIs, varying the aforementioned parameters in addition to ROI number. An analysis of the effects of these varied calculation parameters on the magnitude and shape of the NPS was conducted. The local NPS varied depending on calculation parameters, particularly at low spatial frequencies below . For the simulation study, NPS calculation error decreased exponentially as ROI number increased. For the Catphan study the NPS magnitude varied as a function of ROI location, which was better observed when using smaller ROI sizes. The image subtraction method for background removal was the most effective at reducing low‐frequency background noise, and produced similar results no matter which ROI size or window function was used. The PCA background removal method with a Hann window function produced the closest match to image subtraction, with an average percent difference of 17.5%. Image noise should be analyzed locally by calculating the NPS for small ROI sizes. A minimum ROI size is recommended based on the chosen radial bin size and image pixel dimensions. As the ROI size decreases, the NPS becomes more dependent on the choice of background removal method and window function. The image subtraction method is most accurate, but other methods can achieve similar accuracy if certain window functions are applied. All dependencies should be analyzed and taken into account when considering the interpretation of the NPS for task‐based image quality assessment.PACS number(s): 87.57.C‐, 87.57.Q‐
Evaluation of the tool “Reg Refine” for user‐guided deformable image registration
Authors: Johnson Perry B. , Padgett Kyle R. , Chen Kuan L. , Dogan Nesrin 
Published: February 2017

“Reg Refine” is a tool available in the MIM Maestro v6.4.5 platform (www.mimsoftware.com) that allows the user to actively participate in the deformable image registration process. The purpose of this work was to evaluate the efficacy of this tool and investigate strategies for how to apply it effectively. This was done by performing DIR on two publicly available ground‐truth models, the Pixel‐based Breathing Thorax Model (POPI) for lung, and the Deformable Image Registration Evaluation Project (DIREP) for head and neck. Image noise matched in both magnitude and texture to clinical CBCT scans was also added to each model to simulate the use case of CBCT–CT alignment. For lung, the results showed Reg Refine effective at improving registration accuracy when controlled by an expert user within the context of large lung deformation. CBCT noise was also shown to have no effect on DIR performance while using the MIM algorithm for this site. For head and neck, the results showed CBCT noise to have a large effect on the accuracy of registration, specifically for low‐contrast structures such as the brainstem and parotid glands. In these cases, the Reg Refine tool was able to improve the registration accuracy when controlled by an expert user. Several strategies for how to achieve these results have been outlined to assist other users and provide feedback for developers of similar tools.PACS number(s): 87.44.Qr, 87.57.nj, 87.57.c
Geometric dose prediction model for hemithoracic intensity‐modulated radiation therapy in mesothelioma patients with two intact lungs
Authors: Kuo LiCheng , Yorke Ellen D. , Dumane Vishruta A. , Foster Amanda , Zhang Zhigang , Mechalakos James G. , Wu Abraham J. , Rosenzweig Kenneth E. , Rimner Andreas 
Published: February 2017

The presence of two intact lungs makes it challenging to reach a tumoricidal dose with hemithoracic pleural intensity‐modulated radiation therapy (IMRT) in patients with malignant pleural mesothelioma (MPM) who underwent pleurectomy/decortications or have unresectable disease. We developed an anatomy‐based model to predict attainable prescription dose before starting optimization. Fifty‐six clinically delivered IMRT plans were analyzed regarding correlation of prescription dose and individual and total lung volumes, planning target volume (PTV), ipsilateral normal lung volume and ratios: contralateral/ipsilateral lung (CIVR); contralateral lung/PTV (CPVR); ipsilateral lung /PTV (IPVR); ipsilateral normal lung /total lung (INTLVR); ipsilateral normal lung/PTV (INLPVR). Spearman's rank correlation and Fisher's exact test were used. Correlation between mean ipsilateral lung dose (MILD) and these volume ratios and between prescription dose and single lung mean doses were studied. The prediction models were validated in 23 subsequent MPM patients. CIVR showed the strongest correlation with dose () and accurately predicted prescription dose in the validation cases. INLPVR and MILD as well as MILD and prescription dose were significantly correlated ( and , respectively) in the training and validation cases. Parameters obtainable directly from planning scan anatomy predict achievable prescription doses for hemithoracic IMRT treatment of MPM patients with two intact lungs.PACS number(s): 87.55.de, 87.55.dk
How dose sparing of cardiac structures correlates with in‐field heart volume and sternal displacement
Authors: Kim Taeho , Reardon Kelli , Trifiletti Daniel M. , Geesey Constance , Sukovich Kaitlyn , Crandley Edwin , Read Paul W. , Wijesooriya Krishni 
Published: February 2017

Cardiac irradiation increases the risk of coronary artery disease in patients with left‐sided breast cancer. Techniques exist to reduce cardiac irradiation, but the optimum technique depends on individual patient anatomy and physiology. We investigated the correlation of delta heart volume in field (dHVIF) and sternal excursion with dose sparing in heart and left anterior descending artery (LAD) to develop quantitative predictive models for expected dose to heart and LAD. A treatment planning study was performed on 97 left‐breast cancer patients who underwent whole breast radiotherapy under deep inspiratory breath hold (DIBH). Two CT datasets, free breathing (FB) and DIBH, were utilized for treatment planning and for determination of the internal anatomy‐based DIBH amplitude. The mean heart and LAD dose were compared between FB and DIBH plans and dose to the heart and LAD as a function of dHVIF and sternal excursion were determined. The [Average (STD); Range] mean heart doses from free breathing and DIBH are and , respectively. The mean LAD doses from free breathing and DIBH are and , respectively. The mean dose reductions with DIBH are for the heart and for LAD. Percent mean dose reductions to the heart and LAD with DIBH are 44% and 67% , respectively, compared to FB. The dHVIF mean dose reduction correlation is for the heart and for LAD (with linear trend and y intercept: 26.0 cGy for the heart, 109.1 cGy for LAD). DIBH amplitude using sternal position was . The DIBH amplitude mean dose reduction correlation is for the heart and for LAD (with linear trend with y intercept: 35.6 cGy for the heart, 102.4 cGy for LAD). The strong correlation of dose sparing to the heart and LAD with dHVIF and sternal excursion suggests that mean dose sparing to heart and LAD can be predicted with either dHVIF or sternal excursion equally well. The metrics proposed could be utilized to allow providers to determine the relative dosimetric benefits of different heart‐sparing techniques as early as time of consultation.PACS number(s): 87.53.Tf
Molecular Confirmation of the Relationship between Candida guilliermondii Fks1p Naturally Occurring Amino Acid Substitutions and Its Intrinsic Reduced Echinocandin Susceptibility
Authors: Dudiuk Catiana , Macedo Daiana , Leonardelli Florencia , Theill Laura , Cabeza Matias S. , Gamarra Soledad , Garcia-Effron Guillermo 
Published: February 2017

ABSTRACT

Candida guilliermondii
shows intrinsic reduced echinocandin susceptibility. It harbors two polymorphisms (L633M and T634A) in the Fks1p hot spot 1 region. Our objective was to confirm that the reduced echinocandin susceptibility of
C. guilliermondii
is due to those naturally occurring substitutions. We constructed a
Saccharomyces cerevisiae
mutant in which a region of the
FKS1
gene (including hot spot 1) was replaced with that from
C. guilliermondii
. The chimeric mutants showed 32-fold increases in echinocandin MIC values, confirming the hypothesis.
Effectiveness of the Gold Standard Programme compared with other smoking cessation interventions in Denmark: a cohort study
Authors: Rasmussen Mette , Fernández Esteve , Tønnesen Hanne 
Published: February 2017

ObjectivesWe compared the effectiveness of the Gold Standard Programme (a comprehensive smoking cessation intervention commonly used in Denmark) with other face-to-face smoking cessation programmes in Denmark after implementation in real life, and we identified factors associated with successful quitting.DesignProspective cohort study.SettingA total of 423 smoking cessation clinics from different settings reported data from 2001 to 2013.ParticipantsIn total, 82 515 patients were registered. Smokers ≥15 years old and attending a programme with planned follow-up were included. Smokers who did not want further contact, who intentionally were not followed up or who lacked information about the intervention they received were excluded. A total of 46 287 smokers were included.InterventionsVarious real-life smoking cessation interventions were identified and compared: The Gold Standard Programme, Come & Quit, crash courses, health promotion counselling (brief intervention) and other interventions.Main outcomeSelf-reported continuous abstinence for 6 months.ResultsOverall, 33% (11 184) were continuously abstinent after 6 months; this value was 24% when non-respondents were considered smokers. The follow-up rate was 74%. Women were less likely to remain abstinent, OR 0.83 (CI 0.79 to 0.87). Short interventions were more effective among men. After adjusting for confounders, the Gold Standard Programme was the only intervention with significant results across sex, increasing the odds of abstinence by 69% for men and 31% for women. In particular, compliance, and to a lesser degree, mild smoking, older age and not being disadvantaged were associated with positive outcomes for both sexes. Compliance increased the odds of abstinence more than 3.5-fold.ConclusionsOver time, Danish smoking cessation interventions have been effective in real life. Compliance is the main predictor of successful quitting. Interestingly, short programmes seem to have relatively strong effects among men, but the absolute numbers are very small. Only the comprehensive Gold Standard Programme works across sexes.
Ground-up circular Higgs Factory ring design and cell length optimization
Authors: Talman Richard 
Published: February 2017

A “ground-up” Higgs Factory design methodology is described. For concreteness, numerical parameter choices are drawn primarily from CEPC, the Circular Electron Positron Collider. The goals are to find: (i) optimal parameters, (ii) improved understanding , (iii) a tentative lattice design. As illustration of the method, six chromaticity-corrected lattices, with cell lengths ranging from 45 m to 280 m, all with identical [Formula: see text] mm or [Formula: see text] mm intersection region optics, are designed and their properties compared. For simplicity only a single “toy ring,” circumference (76 km), with one interaction point, and a single beam energy (120 GeV) is considered. For the cell-length optimization a figure of merit FOM (essentially integrated luminosity) is maximized consistent with a dimensionless “fine tuning penalty function” or figure of demerit FOD not being allowed to exceed a conservatively chosen upper limit. The tentative recommendation from this investigation is that the optimal CEPC route is (except for obvious changes) to simply copy LEP: 80 m cell length and two-in-one single-ring operation. The main luminosity-increasing improvements are increased radius and power, top-off-full-energy-injection, noninterleaved sextupoles, more than 100 beam bunch operation, and improved intersection region design. Local chromaticity compensation (with its inevitable intense hard X-rays incident on the detectors) is found to be unnecessary. With these changes luminosity in excess of [Formula: see text] is projected to be achievable.
Epidemiology of isolated foot burns in children presenting to a Queensland paediatric burns centre— a two-year study in warmer climate
Authors: Ngu Florence , Patel Bhaveshkumar , McBride Craig 
Published: February 2017

Abstract

Background
European studies of paediatric foot burns report scalds as the leading cause. Mechanisms of injury are different in warmer climates. We sought to characterize the mechanisms and outcomes of isolated foot burns in our population.

Methods
Retrospective review of a prospectively collected database of all children aged 0–15 years presenting to a Queensland paediatric burns centre over a 26-month period. Non-parametric analyses such as the Mann-Whitney U and Pearson Chi-square were used.

Results
There were 218 children with foot burns treated over a period of 2 years and 2 months of which 214 had complete records. There were significantly more boys than girls (n = 134, 62.6% cf. n = 80, 37.4%, p &lt; 0.0001). The leading mechanism of injury was a contact burn accounting for 63.1% (n = 135) followed by scalds (23.8%, n = 51). Friction, flame and chemical burns were a minority but were significantly deeper (p = 0.03) and significantly more likely to require grafting (p = 0.04) and scar management (p &lt; 0.0001) compared to contact and scald burns.

Conclusions
In our population, contact burns are the most common mechanism of injury causing burns to the feet. The leading aetiology is campfire burns, which account for one-third of all burns to the feet. Prevention campaigns targeted at this population could significantly reduce the burden of morbidity from these burns. Friction, flame and chemical burns constitute a minority of patients but are deeper and more likely to require skin grafting and scar management.