bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dosimetry for nonuniform activity distributions: A method for the calculation of 3D absorbed‐dose distribution without the use of voxel S‐values, point kernels, or Monte Carlo simulations
Authors: Traino A. C. , Marcatili S. , Avigo C. , Sollini M. , Erba P. A. , Mariani G. 
Published: March 2013

Purpose:Nonuniform activity within the target lesions and the critical organs constitutes an important limitation for dosimetric estimates in patients treated with tumor‐seeking radiopharmaceuticals. The tumor control probability and the normal tissue complication probability are affected by the distribution of the radionuclide in the treated organ/tissue. In this paper, a straightforward method for calculating the absorbed dose at the voxel level is described. This new method takes into account a nonuniform activity distribution in the target/organ.Methods:The new method is based on the macroscopicS‐values (i.e., the S‐values calculated for the various organs, as defined in the MIRD approach), on the definition of the number of voxels, and on the raw‐count 3D array, corrected for attenuation, scatter, and collimator resolution, in the lesion/organ considered. Starting from these parameters, the only mathematical operation required is to multiply the 3D array by a scalar value, thus avoiding all the complex operations involving the 3D arrays.Results:A comparison with the MIRD approach, fully described in the MIRD Pamphlet No. 17, usingS‐values at the voxel level, showed a good agreement between the two methods for 131I and for 90Y.Conclusions:Voxel dosimetry is becoming more and more important when performing therapy with tumor‐seeking radiopharmaceuticals. The method presented here does not require calculating theS‐values at the voxel level, and thus bypasses the mathematical problems linked to the convolution of 3D arrays and to the voxel size. In the paper, the results obtained with this new simplified method as well as the possibility of using it for other radionuclides commonly employed in therapy are discussed. The possibility of using the correct density value of the tissue/organs involved is also discussed.
Automatic patient alignment system using 3D ultrasound
Authors: Kaar Marcus , Figl Michael , Hoffmann Rainer , Birkfellner Wolfgang , Hummel Johann , Stock Markus , Georg Dietmar , Goldner Gregor 
Published: March 2013

Purpose:Recent developments in radiation therapy such as intensity modulated radiotherapy (IMRT) or dose painting promise to provide better dose distribution on the tumor. For effective application of these methods the exact positioning of the patient and the localization of the irradiated organ and surrounding structures is crucial. Especially with respect to the treatment of the prostate, ultrasound (US) allows for differentiation between soft tissue and was therefore applied by various repositioning systems, such as BAT or Clarity. The authors built a new system which uses 3D US at both sites, the CT room and the intervention room and applied a 3D/3D US/US registration for automatic repositioning.Methods:In a first step the authors applied image preprocessing methods to prepare the US images for an optimal registration process. For the 3D/3D registration procedure five different metrics were evaluated. To find the image metric which fits best for a particular patient three 3D US images were taken at the CT site and registered to each other. From these results an US registration error was calculated. The most successful image metric was then applied for the US/US registration process. The success of the whole repositioning method was assessed by taking the results of an ExacTrac system as golden standard.Results:The US/US registration error was found to be 2.99 ± 1.54 mm with respect to the mutual information metric by Mattes (eleven patients) which revealed to be the most suitable of the assessed metrics. For complete repositioning chain the error amounted to 4.15 ± 1.20 mm (ten patients).Conclusions:The authors developed a system for patient repositioning which works automatically without the necessity of user interaction with an accuracy which seems to be suitable for clinical application.
Loss of local control due to tumor displacement as a function of margin size, dose–response slope, and number of fractions
Authors: Selvaraj Jothybasu , Uzan Julien , Baker Colin , Nahum Alan 
Published: March 2013

Purpose:Geometric uncertainties are inevitable in radiotherapy. To account for these uncertainties, a margin is added to the clinical target volume (CTV) to create the planning target volume (PTV), and its size is critical for obtaining an optimal treatment plan. Dose‐based (i.e., physical) margin recipes have been published and widely used, but it is important to consider fractionation and the radiobiological characteristics of the tumor when deriving margins. Hence a tumor control probability (TCP)‐based margin is arguably more appropriate.Methods:Margins required for ≤1% loss in mean population TCP (relative to a static tumor) for varying numbers of fractions, varying slope of the dose–response curve (γ50) and varying degrees of dose distribution conformity are investigated for spherical and four‐field (4F)‐brick dose distributions. To simulate geometric uncertainties, systematic (Σ) and random (σ) tumor displacements were sampled from Gaussian distributions and applied to each fraction for a spherical CTV. Interfraction tumor motion was simulated and the dose accumulated from fraction to fraction on a voxel‐by‐voxel basis to calculate TCP. PTV margins derived from this work for various fraction numbers and dose–response slopes (γ50) for different degrees of geometric uncertainties are compared with margins calculated using published physical‐dose‐ and TCP‐based recipes.Results:Larger margins are required for a decrease in the number of fractions and for an increase in γ50 for both spherical and 4F‐brick dose distributions. However, the margins can be close to zero for the 4F‐brick distribution for small geometric uncertainties (Σ = 1, σ = 1 mm) irrespective of the number of fractions and the magnitude of γ50 due to the higher “incidental” dose outside the tumor. For Σ = 1 mm and σ = 3 mm, physical‐dose‐based recipes underestimate the margin only for the combination of hypofractionated treatments and tumors with a high γ50. For all other situations TCP‐based margins are smaller than physical‐dose‐based recipes.Conclusions:Margins depend on the number of fractions and γ50 in addition to Σ and σ. Dose conformity should also be considered since the required margin increases with increasing dose conformity. Ideally margins should be anisotropic and individualized, taking into account γ50, number of fractions, and the dose distribution, as well as estimates of Σ and σ. No single “recipe” can adequately account for all these variables.
Modeling respiratory motion for reducing motion artifacts in 4D CT images
Authors: Zhang Yongbin , Yang Jinzhong , Zhang Lifei , Court Laurence E. , Balter Peter A. , Dong Lei 
Published: March 2013

Purpose:Four‐dimensional computed tomography (4D CT) images have been recently adopted in radiation treatment planning for thoracic and abdominal cancers to explicitly define respiratory motion and anatomy deformation. However, significant image distortions (artifacts) exist in 4D CT images that may affect accurate tumor delineation and the shape representation of normal anatomy. In this study, the authors present a patient‐specific respiratory motion model, based on principal component analysis (PCA) of motion vectors obtained from deformable image registration, with the main goal of reducing image artifacts caused by irregular motion during 4D CT acquisition.Methods:For a 4D CT image set of a specific patient, the authors calculated displacement vector fields relative to a reference phase, using an in‐house deformable image registration method. The authors then used PCA to decompose each of the displacement vector fields into linear combinations of principal motion bases. The authors have demonstrated that the regular respiratory motion of a patient can be accurately represented by a subspace spanned by three principal motion bases and their projections. These projections were parameterized using a spline model to allow the reconstruction of the displacement vector fields at any given phase in a respiratory cycle. Finally, the displacement vector fields were used to deform the reference CT image to synthesize CT images at the selected phase with much reduced image artifacts.Results:The authors evaluated the performance of the in‐house deformable image registration method using benchmark datasets consisting of ten 4D CT sets annotated with 300 landmark pairs that were approved by physicians. The initial large discrepancies across the landmark pairs were significantly reduced after deformable registration, and the accuracy was similar to or better than that reported by state‐of‐the‐art methods. The proposed motion model was quantitatively validated on 4D CT images of a phantom and a lung cancer patient by comparing the synthesized images and the original images at different phases. The synthesized images matched well with the original images. The motion model was used to reduce irregular motion artifacts in the 4D CT images of three lung cancer patients. Visual assessment indicated that the proposed approach could reduce severe image artifacts. The shape distortions around the diaphragm and tumor regions were mitigated in the synthesized 4D CT images.Conclusions:The authors have derived a mathematical model to represent the regular respiratory motion from a patient‐specific 4D CT set and have demonstrated its application in reducing irregular motion artifacts in 4D CT images. The authors’ approach can mitigate shape distortions of anatomy caused by irregular breathing motion during 4D CT acquisition.
Investigation of gated cone‐beam CT to reduce respiratory motion blurring
Authors: Kincaid Russell E. , Yorke Ellen D. , Goodman Karyn A. , Rimner Andreas , Wu Abraham J. , Mageras Gig S. 
Published: March 2013

Purpose:Methods of reducing respiratory motion blurring in cone‐beam CT (CBCT) have been limited to lung where soft tissue contrast is large. Respiration‐correlated cone‐beam CT uses slow continuous gantry rotation but image quality is limited by uneven projection spacing. This study investigates the efficacy of a novel gated CBCT technique.Methods:In gated CBCT, the linac is programmed such that gantry rotation and kV image acquisition occur within a gate around end expiration and are triggered by an external respiratory monitor. Standard CBCT and gated CBCT scans are performed in 22 patients (11 thoracic, 11 abdominal) and a respiration‐correlated CT (RCCT) scan, acquired on a standard CT scanner, from the same day serves as a criterion standard. Image quality is compared by calculating contrast‐to‐noise ratios (CNR) for tumors in lung, gastroesophageal junction (GEJ) tissue, and pancreas tissue, relative to surrounding background tissue. Congruence between the object in the CBCT images and that in the RCCT is measured by calculating the optimized normalized cross‐correlation (NCC) following CBCT‐to‐RCCT rigid registrations.Results:Gated CBCT results in reduced motion artifacts relative to standard CBCT, with better visualization of tumors in lung, and of abdominal organs including GEJ, pancreas, and organs at risk. CNR of lung tumors is larger in gated CBCT in 6 of 11 cases relative to standard CBCT. A paired two‐tailedt‐test of lung patient mean CNR shows no statistical significance (p = 0.133). In 4 of 5 cases where CNR is not increased, lung tumor motion observed in RCCT is small (range 1.3–5.2 mm). CNR is increased and becomes statistically significant for 6 out of 7 lung patients with > 5 mm tumor motion (p = 0.044). CNR is larger in gated CBCT in 5 of 7 GEJ cases and 3 of 4 pancreas cases (p = 0.082 and 0.192). Gated CBCT yields improvement with lower NCC relative to standard CBCT in 10 of 11, 7 of 7, and 3 of 4 patients for lung, GEJ, and pancreas images, respectively (p = 0.0014, 0.0030, 0.165).Conclusions:Gated CBCT reduces image blurring caused by respiratory motion. The gated gantry rotation yields uniformly and closely spaced projections resulting in improved reconstructed image quality. The technique is shown to be applicable to abdominal sites, where image contrast of soft tissues is low.
Geometrical splitting technique to improve the computational efficiency in Monte Carlo calculations for proton therapy
Authors: Ramos‐Méndez José , Perl Joseph , Faddegon Bruce , Schümann Jan , Paganetti Harald 
Published: March 2013

Purpose:To present the implementation and validation of a geometrical based variance reduction technique for the calculation of phase space data for proton therapy dose calculation.Methods:The treatment heads at the Francis H Burr Proton Therapy Center were modeled with a new Monte Carlo tool (TOPAS based on Geant4). For variance reduction purposes, two particle‐splitting planes were implemented. First, the particles were split upstream of the second scatterer or at the second ionization chamber. Then, particles reaching another plane immediately upstream of the field specific aperture were split again. In each case, particles were split by a factor of 8. At the second ionization chamber and at the latter plane, the cylindrical symmetry of the proton beam was exploited to position the split particles at randomly spaced locations rotated around the beam axis. Phase space data in IAEA format were recorded at the treatment head exit and the computational efficiency was calculated. Depth–dose curves and beam profiles were analyzed. Dose distributions were compared for a voxelized water phantom for different treatment fields for both the reference and optimized simulations. In addition, dose in two patients was simulated with and without particle splitting to compare the efficiency and accuracy of the technique.Results:A normalized computational efficiency gain of a factor of 10–20.3 was reached for phase space calculations for the different treatment head options simulated. Depth–dose curves and beam profiles were in reasonable agreement with the simulation done without splitting: within 1% for depth–dose with an average difference of (0.2 ± 0.4)%, 1 standard deviation, and a 0.3% statistical uncertainty of the simulations in the high dose region; 1.6% for planar fluence with an average difference of (0.4 ± 0.5)% and a statistical uncertainty of 0.3% in the high fluence region. The percentage differences between dose distributions in water for simulations done with and without particle splitting were within the accepted clinical tolerance of 2%, with a 0.4% statistical uncertainty. For the two patient geometries considered, head and prostate, the efficiency gain was 20.9 and 14.7, respectively, with the percentages of voxels with gamma indices lower than unity 98.9% and 99.7%, respectively, using 2% and 2 mm criteria.Conclusions:The authors have implemented an efficient variance reduction technique with significant speed improvements for proton Monte Carlo simulations. The method can be transferred to other codes and other treatment heads.
Influence of Acupuncture on the Outcomes of in Vitro Fertilisation When Embryo Implantation Has Failed: A Prospective Randomised Controlled Clinical Trial
Authors: di Villahermosa Daniela Isoyama Manca , dos Santos Lara Guercio , Nogueira Mariana Balthazar , Vilarino Fabia Lima , Barbosa Caio Parente 
Published: March 2013

Objective To evaluate the effectiveness of acupuncture and moxibustion as an adjuvant treatment in women undergoing in vitro fertilisation (IVF) when embryo implantation has failed. Methods A prospective, randomised controlled clinical trial was conducted with 84 infertile patients who had had at least two unsuccessful attempts of IVF. The patients were randomised in three groups: control (n=28), sham (n=28) and acupuncture (n=28). The sample size was calculated by assuming a pregnancy rate of 10% when embryo implantation had failed. The pregnancy rates of the current IVF cycle were evaluated by measurement of blood β human chorionic gonadotrophin (βhCG) and subsequent transvaginal ultrasound. Acupuncture was performed on the first and seventh day of ovulation induction, on the day before ovarian puncture and on the day after embryo transfer. In the acupuncture group, patients were treated with moxibustion at nine acupuncture points (BL18, BL22, BL23, BL52, CV3, CV4, CV5, CV7, GV4) and needling at 12 points. In the sham group needles were inserted in eight areas that did not correspond to known acupuncture points. Results The clinical pregnancy rate in the acupuncture group was significantly higher than that in the control and sham groups (35.7% vs 7.1% vs 10.7%; p=0.0169). Conclusions In this study, acupuncture and moxibustion increased pregnancy rates when used as an adjuvant treatment in women undergoing IVF, when embryo implantation had failed.
Upper limb international spasticity study: rationale and protocol for a large, international, multicentre prospective cohort study investigating management and goal attainment following treatment with botulinum toxin A in real-life clinical practice
Authors: Turner-Stokes Lynne , Fheodoroff Klemens , Jacinto Jorge , Maisonobe Pascal , Zakine Benjamin 
Published: March 2013

ObjectivesThis article provides an overview of the Upper Limb International Spasticity (ULIS) programme, which aims to develop a common core dataset for evaluation of real-life practice and outcomes in the treatment of upper-limb spasticity with botulinum toxin A (BoNT-A). Here we present the study protocol for ULIS-II, a large, international cohort study, to describe the rationale and steps to ensure the validity of goal attainment scaling (GAS) as the primary outcome measure.Methods and analysis designAn international, multicentre, observational, prospective, before-and-after study, conducted at 84 centres in 22 countries across three continents.Participants468 adults presenting with poststroke upper limb spasticity in whom a decision had already been made to inject BoNT-A (5–12 consecutive participants recruited per centre).InterventionsPhysicians were free to choose targeted muscles, BoNT-A preparation, injected doses/technique and timing of follow-up in accordance with their usual practice and the goals for treatment. Primary outcome measure: GAS. Secondary outcomes: Measurements of spasticity, standardised outcome measures and global benefits. Steps to ensure validity included: (1) targeted training of all investigators in the use of GAS; (2) within-study validation of goal statements and (3) establishment of an electronic case report form with an in-built tracking facility for separation of baseline/follow-up data.AnalysisEfficacy population: all participants who had (1) BoNT-A injection and (2) subsequent assessment of GAS. Primary efficacy variable: percentage (95% CI) achievement of the primary goal from GAS following one BoNT-A injection cycle.Ethics and disseminationThis non-interventional study is conducted in compliance with guidelines for good pharmacoepidemiology practices. Appropriate ethical approvals were obtained according to local regulations. ULIS-II will provide important information regarding treatment and outcomes from BoNT-A in real-life upper limb spasticity management. The results will be published separately.RegistrationClinicalTrials.gov identifier:NCT01020500.
Young adult women smokers’ response to using plain cigarette packaging: a naturalistic approach
Authors: Moodie Crawford S , Mackintosh Anne Marie 
Published: March 2013

ObjectivesTo explore young adult women smokers’ cognitive and emotional response to using dark brown ‘plain’ cigarette packs in natural settings and whether plain packaging is associated with any short-term change in smoking behaviour.DesignA naturalistic approach. Participants used plain cigarette packs provided to them for 1 week and for 1 week their own fully branded packs, but otherwise smoked and socialised as normal. Participants completed questionnaires twice a week.SettingThe six most populated cities and towns in Scotland.Participants301 young women smokers were recruited, with a final sample of 187 (62.1%). To meet the inclusion criteria women had to be between the ages of 18 and 35, daily cigarette smokers and provide a breath sample to confirm smoking status.Primary and secondary outcome measuresPack perceptions and feelings, feelings about smoking, salience and perceptions of health warnings and avoidant and cessation behaviours.ResultsIn comparison to fully branded packaging, plain packaging was associated with more negative perceptions and feelings about the pack and about smoking (p<0.001). No significant overall differences in salience, seriousness or believability of health warnings were found between the pack types, but participants reported looking more closely at the warnings on plain packs and also thinking more about what the warnings were telling them (p<0.001). Participants reported being more likely to engage in avoidant behaviours, such as hiding or covering the pack (p<0.001), and cessation behaviours, such as foregoing cigarettes (p<0.05), smoking less around others (p<0.001), thinking about quitting (p<0.001) and reduced consumption (p<0.05), while using the plain packs. Results did not differ by dependence level or socioeconomic status.ConclusionsNo research design can capture the true impacts of plain packaging prior to its introduction, but this study suggests that plain packaging may help reduce cigarette consumption and encourage cessation in the short term.
Co-ACT—a framework for observing coordination behaviour in acute care teams
Authors: Kolbe Michaela , Burtscher Michael Josef , Manser Tanja 
Published: March 2013

BackgroundAcute care teams (ACTs) represent action teams, that is, teams in which members with specialised roles must coordinate their actions during intense situations, often under high time pressure and with unstable team membership. Using behaviour observation, patient safety research has been focusing on defining teamwork behaviours—particularly coordination—that are critical for patient safety during these intense situations. As one result of this divergent research landscape, the number, scope and variety of applied behaviour observation taxonomies are growing, making comparison and convergent integration of research findings difficult.AimTo facilitate future ACT research by presenting a framework that provides a shared language of teamwork behaviours, allows for comparing previous and future ACT research and offers a measurement tool for ACT observation.MethodBased on teamwork theory and empirical evidence, we developed Co-ACT—the Framework for Observing Coordination Behaviour in ACT. Integrating two previous, extensive taxonomies into Co-ACT, we also suggested 12 behavioural codes for which we determined inter-rater reliability by analysing the teamwork of videotaped anaesthesia teams in the clinical setting.ResultsThe Co-ACT framework consists of four quadrants organised along two dimensions (explicit vs implicit coordination; action vs information coordination). Each quadrant provides three categories for which Cohen's κ overall value was substantial; but values for single categories varied considerably.ConclusionsCo-ACT provides a framework for organising behaviour codes and offers respective categories for succinctly measuring teamwork in ACTs. Furthermore, it has the potential to allow for guiding and comparing ACTs study results. Future work using Co-ACT in different research and training settings will show how well it can generally be applied across ACTs.