bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mesenchymal stem cell therapy for knee osteoarthritis. Preliminary report of four patients
Authors: DAVATCHI Fereydoun , ABDOLLAHI Bahar SADEGHI , MOHYEDDIN Mandana , SHAHRAM Farhad , NIKBIN Behrooz 
Published: March 2011

AbstractBackground:  Osteoarthritis (OA) is a cartilage degenerative process, involving the immune system, producing local inflammatory reactions, with production of pro‐inflammatory cytokines and metalloproteinases. No treatment is still available to improve or reverse the process. Stem cell therapy opened new horizons for treatment of many incurable diseases. Mesenchymal stem cells (MSCs) due to their multi‐lineage potential, immunosuppressive activities, limited immunogenicity and relative ease of growth in culture, have attracted attentions for clinical use.Aim:  The aim of this study was to examine whether MSC transplantation could reverse the OA process in the knee joint. The project was approved by the Tehran University of Medical Sciences Research Committee and Ethical Committee.Patients and Methods:  Four patients with knee osteoarthritis were selected for the study. They were aged 55, 57, 65 and 54 years, and had moderate to severe knee OA. After their signed written consent, 30 mL of bone marrow were taken and cultured for MSC growth. After having enough MSCs in culture (4–5 weeks) and taking in consideration all safety measures, cells were injected in one knee of each patient.Results:  The walking time for the pain to appear improved for three patients and remained unchanged for one. The number of stairs they could climb and the pain on visual analog scale improved for all of them. On physical examination, the improvement was mainly for crepitus. It was minor for the improvement of the range of motion.Conclusion:  Results were encouraging, but not excellent. Improvement of the technique may improve the results.
Can we reduce routine blood ordering in spinal surgery?
Authors: KOURITAS VASILEIOS , GRAHAM STEVE , MARWAH GAUTAM , PAPASTEFANOU SOTIRIS L. 
Published: March 2011

SUMMARYSpinal reconstruction can be associated with major blood loss; because of the non existence of ordering guidelines, blood products are ordered preoperatively in excessive quantities. The aim of our study was to investigate the efficiency of our ordering routine.The records of 205 spinal surgery patients, over a period of 3 years were reviewed. The crossmatched to transfused (C‐T) ratio was calculated for each pathology group and the safe number of units transfused was determined.A total of 929 units were crossmatched, whereas 84 patients required transfusion. In all, 404 units were not used (C‐T ratio = 1.8). The greatest number of unused but cross matched units was observed in painful back surgery (C‐T ratio = 3.9, P < 0.01 vs. other pathologies). For all the other pathology groups (scoliosis, tumor and fracture) fewer units can be ordered, except in neuromuscular scoliosis group (6 units used on average for each case). For spinal fusion, artificial disc replacement or simple discectomy, a group and save routine is adequate.In conclusion, less blood can be ordered for spinal surgery, except for cases of neuromuscular scoliosis. The blood units crossmatched for painful back surgery, were more than actually needed. With technological advancement historical blood crossmatching policies may need re‐evaluation.
Training young horses to social separation: Effect of a companion horse on training efficiency
Authors: HARTMANN E. , CHRISTENSEN J. W. , KEELING L. J. 
Published: March 2011

SummaryReasons for performing study: The intensity with which a horse responds to separation from its group and subsequently to being alone is relevant for both horse and handler safety. Identification of training methods that may reduce responses to separation would be useful in practice.Objectives: To investigate whether the initial presence of a familiar companion horse modifies responses to separation from the group, lowers stress levels (as measured by heart rate) and increases training efficiency.Hypothesis: Habituation to separation proceeds more quickly if the horse is first trained with a companion, and heart rate is lower when the horse is subsequently trained alone, compared to control horses trained individually from the start.Methods: Young mares (n = 32), kept in groups of 4 were exposed to social separation: 2 horses of the group were trained singly (S1, n = 16) and the remaining 2 horses (n = 16) were trained first with a companion (P2) and then alone (P1). The training comprised 3 steps whereby distance from the group was gradually increased. The final learning criterion was met when a horse fed calmly alone inside a test arena (Step 3). Horses that were trained in a pair had to succeed in Step 3 together before they repeated the steps alone. Feeding behaviour and heart rate were recorded.Results: There were no significant differences between S1 and P1 horses, indicating that the initial pair‐training did not reduce responses in P1 horses. However, heart rate was significantly lower when horses were trained in pairs (P2) compared to when the same horses were subsequently trained alone (P1).Conclusions and potential relevance: It may not be efficient to habituate naïve young horses to social separation initially with a partner as these horses appear to have to relearn being in the test situation alone when switching to the individual training.
Organ doses for reference adult male and female undergoing computed tomography estimated by Monte Carlo simulations
Authors: Lee Choonsik , Kim Kwang Pyo , Long Daniel , Fisher Ryan , Tien Chris , Simon Steven L. , Bouville Andre , Bolch Wesley E. 
Published: March 2011

Purpose:To develop a computed tomography (CT) organ dose estimation method designed to readily provide organ doses in a reference adult male and female for different scan ranges to investigate the degree to which existing commercial programs can reasonably match organ doses defined in these more anatomically realistic adult hybrid phantomsMethods:The x‐ray fan beam in the SOMATOM Sensation 16 multidetector CT scanner was simulated within the Monte Carlo radiation transport codeMCNPX2.6. The simulated CT scanner model was validated through comparison with experimentally measured lateral free‐in‐air dose profiles and computed tomography dose index (CTDI) values. The reference adult male and female hybrid phantoms were coupled with the established CT scanner model following arm removal to simulate clinical head and other body region scans. A set of organ dose matrices were calculated for a series of consecutive axial scans ranging from the top of the head to the bottom of the phantoms with a beam thickness of 10 mm and the tube potentials of 80, 100, and 120 kVp. The organ doses for head, chest, and abdomen/pelvis examinations were calculated based on the organ dose matrices and compared to those obtained from two commercial programs, CT‐EXPO and CTDOSIMETRY. Organ dose calculations were repeated for an adult stylized phantom by using the same simulation method used for the adult hybrid phantom.Results:Comparisons of both lateral free‐in‐air dose profiles and CTDI values through experimental measurement with the Monte Carlo simulations showed good agreement to within 9%. Organ doses for head, chest, and abdomen/pelvis scans reported in the commercial programs exceeded those from the Monte Carlo calculations in both the hybrid and stylized phantoms in this study, sometimes by orders of magnitude.Conclusions:The organ dose estimation method and dose matrices established in this study readily provides organ doses for a reference adult male and female for different CT scan ranges and technical parameters. Organ doses from existing commercial programs do not reasonably match organ doses calculated for the hybrid phantoms due to differences in phantom anatomy, as well as differences in organ dose scaling parameters. The organ dose matrices developed in this study will be extended to cover different technical parameters, CT scanner models, and various age groups.
Concurrent quantification of multiple nanoparticle bound states
Authors: Rauwerdink Adam M. , Weaver John B. 
Published: March 2011

Purpose:The binding of nanoparticles toin vivo targets impacts their use for medical imaging, therapy, and the study of diseases and disease biomarkers. Though an array of techniques can detect binding in vitro, the search for a robust in vivo method continues. The spectral response of magnetic nanoparticles can be influenced by a variety of changes in their physical environment including viscosity and binding. Here, the authors show that nanoparticles in these different environmental states produce spectral responses, which are sufficiently unique to allow for simultaneous quantification of the proportion of nanoparticles within each state.Methods:The authors measured the response to restricted Brownian motion using an array of magnetic nanoparticle designs. With a chosen optimal particle type, the authors prepared particle samples in three distinct environmental states. Various combinations of particles within these three states were measured concurrently and the authors attempted to solve for the quantity of particles within each physical state.Results:The authors found the spectral response of the nanoparticles to be sufficiently unique to allow for accurate quantification of up to three bound states with errors on the order of 1.5%. Furthermore, the authors discuss numerous paths for translating these measurements toin vivo applications.Conclusions:Multiple nanoparticle environmental states can be concurrently quantified using the spectral response of the particles. Such an ability, if translated to thein vivo realm, could provide valuable information about the fate of nanoparticles in vivo or improve the efficacy of nanoparticle based treatments.
Shortening treatment time in robotic radiosurgery using a novel node reduction technique
Authors: van de Water Steven , Hoogeman Mischa S. , Breedveld Sebastiaan , Heijmen Ben J. M. 
Published: March 2011

Purpose:The fraction duration of robotic radiosurgery treatments can be reduced by generating more time‐efficient treatment plans with a reduced number of node positions, beams, and monitor units (MUs). Node positions are preprogramed locations where the robot can position the focal spot of the x‐ray beam. As the time needed for the robot to travel between node positions takes up a large part of the treatment time, the aim of this study was to develop and evaluate a node reduction technique in order to reduce the treatment time per fraction for robotic radiosurgery.Methods:Node reduction was integrated into the inverse planning algorithm, developed in‐house for the robotic radiosurgery modality. It involved repeated inverse optimization, each iteration excluding low‐contribution node positions from the planning and resampling new candidate beams from the remaining node positions. Node reduction was performed until the exclusion of a single node position caused a constraint violation, after which the shortest treatment plan was selected retrospectively. Treatment plans were generated with and without node reduction for two lung cases of different complexity, one oropharyngeal case and one prostate case. Plan quality was assessed using the number of node positions, beams and MUs, and the estimated treatment time per fraction. All treatment plans had to fulfill all clinical dose constraints. Extra constraints were added to maintain the low‐dose conformality and restrict skin doses during node reduction.Results:Node reduction resulted in 12 residual node positions, on average (reduction by 77%), at the cost of an increase in the number of beams and total MUs of 28% and 9%, respectively. Overall fraction durations (excluding patient setup) were shortened by 25% (range of 18%–40%), on average. Dose distributions changed only little and dose in low‐dose regions was effectively restricted by the additional constraints.Conclusions:The fraction duration of robotic radiosurgery treatments can be reduced considerably by node reduction with minimal changes in dosimetrical plan quality. Additional constraints are required to guarantee low‐dose conformality and to avoid unacceptable skin dose.
Ultrafast convolution/superposition using tabulated and exponential kernels on GPU
Authors: Chen Quan , Chen Mingli , Lu Weiguo 
Published: March 2011

Purpose:Collapsed‐cone convolution/superposition (CCCS) dose calculation is the workhorse for IMRT dose calculation. The authors present a novel algorithm for computing CCCS dose on the modern graphic processing unit (GPU).Methods:The GPU algorithm includes a novel TERMA calculation that has no write‐conflicts and has linear computation complexity. The CCCS algorithm uses either tabulated or exponential cumulative‐cumulative kernels (CCKs) as reported in literature. The authors have demonstrated that the use of exponential kernels can reduce the computation complexity by order of a dimension and achieve excellent accuracy. Special attentions are paid to the unique architecture of GPU, especially the memory accessing pattern, which increases performance by more than tenfold.Results:As a result, the tabulated kernel implementation in GPU is two to three times faster than other GPU implementations reported in literature. The implementation of CCCS showed significant speedup on GPU over single core CPU. On tabulated CCK, speedups as high as 70 are observed; on exponential CCK, speedups as high as 90 are observed.Conclusions:Overall, the GPU algorithm using exponential CCK is 1000–3000 times faster over a highly optimized single‐threaded CPU implementation using tabulated CCK, while the dose differences are within 0.5% and 0.5 mm. This ultrafast CCCS algorithm will allow many time‐sensitive applications to use accurate dose calculation.
Objective characterization of GE Discovery CT750 HD scanner: Gemstone spectral imaging mode
Authors: Zhang Da , Li Xinhua , Liu Bob 
Published: March 2011

Purpose:To objectively characterize the performance of the gemstone spectral imaging (GSI) mode of GE CT750 HD scanner from a user's perspective.Methods:A regular scan protocol that approximates the adult abdomen scan protocol frequently used in the authors' institute was selected as the baseline, and a GSI protocol (preset 11) that is similar to the regular protocol and has a moderate dose level was compared to the baseline protocol. The resolving power of both protocols was characterized in terms of modulation transfer functions and high contrast resolution bar readings. Their noise characteristics were studied through noise power spectra, and their low contrast detectability was compared via contrast‐to‐noise ratio. Material decomposition capability of GSI was evaluated by scanning iodine solutions of 9–24 mg/ml iodine concentration in a Gammex CT phantom and by examining the estimated iodine concentration. In addition, a formula describing the dependency of HU in iodine enhanced area on GSI monochromatic energies and iodine concentrations was provided and the theoretical values were compared with the measured results.Results:The resolutions levels of 50%, 10%, and 5% MTF of GSI monochromatic images at 65 keV agree with those of the regular protocol within 0.1 lp/cm. GSI monochromatic images at 65 keV demonstrated the lowest noise level among GSI images of different monochromatic energies and showed very similar noise magnitude and noise power distribution as compared to the regular protocol images. The CNR of 60 and 65 keV GSI monoimages are approximately 100% of those of the regular protocol images. Estimated iodine concentration levels agreed with the actual values within 2% when the iodine solutions were placed at 3, 9, 12 o'clock positions of the phantom; when iodine solutions were placed at the phantom center and at 6 o'clock position, higher discrepancies of 2%–10% were observed. The observed dependency of HU on keV and iodine concentration levels agreed with the expectation from x‐ray attenuations.Conclusions:Equivalent performances were observed in the comparison between GSI 65 keV monochromatic images and images from a regular abdomen scan protocol. This suggests the possibility of GSI to be employed in routine abdominal scans, which would potentially offer more information through its capabilities of material decomposition.
Material separation in x‐ray CT with energy resolved photon‐counting detectors
Authors: Wang Xiaolan , Meier Dirk , Taguchi Katsuyuki , Wagenaar Douglas J. , Patt Bradley E. , Frey Eric C. 
Published: March 2011

Purpose:The objective of the study was to demonstrate that, in x‐ray computed tomography (CT), more than two types of materials can be effectively separated with the use of an energy resolved photon‐counting detector and classification methodology. Specifically, this applies to the case when contrast agents that contain K‐absorption edges in the energy range of interest are present in the object. This separation is enabled via the use of recently developed energy resolved photon‐counting detectors with multiple thresholds, which allow simultaneous measurements of the x‐ray attenuation at multiple energies.Methods:To demonstrate this capability, we performed simulations and physical experiments using a six‐threshold energy resolved photon‐counting detector. We imaged mouse‐sized cylindrical phantoms filled with several soft‐tissue‐like and bone‐like materials and with iodine‐based and gadolinium‐based contrast agents. The linear attenuation coefficients were reconstructed for each material in each energy window and were visualized as scatter plots between pairs of energy windows. For comparison, a dual‐kVp CT was also simulated using the same phantom materials. In this case, the linear attenuation coefficients at the lower kVp were plotted against those at the higher kVp.Results:In both the simulations and the physical experiments, the contrast agents were easily separable from other soft‐tissue‐like and bone‐like materials, thanks to the availability of the attenuation coefficient measurements at more than two energies provided by the energy resolved photon‐counting detector. In the simulations, the amount of separation was observed to be proportional to the concentration of the contrast agents; however, this was not observed in the physical experiments due to limitations of the real detector system. We used the angle between pairs of attenuation coefficient vectors in either the 5‐D space (for non‐contrast‐agent materials using energy resolved photon‐counting acquisition) or a 2‐D space (for contrast agents using energy resolved photon‐counting acquisition and all materials using dual‐kVp acquisition) as a measure of the degree of separation. Compared to dual‐kVp techniques, an energy resolved detector provided a larger separation and the ability to separate different target materials using measurements acquired in different energy window pairs with a single x‐ray exposure.Conclusions:We concluded that x‐ray CT with an energy resolved photon‐counting detector with more than two energy windows allows the separation of more than two types of materials, e.g., soft‐tissue‐like, bone‐like, and one or more materials with K‐edges in the energy range of interest. Separating material types using energy resolved photon‐counting detectors has a number of advantages over dual‐kVp CT in terms of the degree of separation and the number of materials that can be separated simultaneously.
When is better best? A multiobjective perspective
Authors: Phillips Mark H. , Holdsworth Clay 
Published: March 2011

Purpose:To identify the most informative methods for reporting results of treatment planning comparisons.Methods:Seven articles from the past year ofInternational Journal of Radiation Oncology Biology Physics reported on comparisons of treatment plans for IMRT and IMAT. The articles were reviewed to identify methods of comparisons. Decision theoretical concepts were used to evaluate the study methods and highlight those that provide the most information.Results:None of the studies examined the correlation between objectives. Statistical comparisons provided some information but not enough to provide support for a robust decision analysis.Conclusions:The increased use of treatment planning studies to evaluate different methods in radiation therapy requires improved standards for designing the studies and reporting the results.
Current status and future perspective of flattening filter free photon beams
Authors: Georg Dietmar , Knöös Tommy , McClean Brendan 
Published: March 2011

Purpose:Flattening filters (FFs) have been considered as an integral part of the treatment head of a medical accelerator for more than 50 years. The reasons for the longstanding use are, however, historical ones. Advanced treatment techniques, such as stereotactic radiotherapy or intensity modulated radiotherapy have stimulated the interest in operating linear accelerators in a flattening filter free (FFF) mode. The current manuscript reviews treatment head physics of FFF beams, describes their characteristics and the resulting potential advantages in their medical use, and closes with an outlook.Methods:A number of dosimetric benefits have been determined for FFF beams, which range from increased dose rate and dose per pulse to favorable output ratio in‐air variation with field size, reduced energy variation across the beam, and reduced leakage and out‐of‐field dose, respectively. Finally, the softer photon spectrum of unflattened beams has implications on imaging strategies and radiation protection.Results:The dosimetric characteristics of FFF beams have an effect on treatment delivery, patient comfort, dose calculation accuracy, beam matching, absorbed dose determination, treatment planning, machine specific quality assurance, imaging, and radiation protection. When considering conventional C‐arm linacs in a FFF mode, more studies are needed to specify and quantify the clinical advantages, especially with respect to treatment plan quality and quality assurance.Conclusions:New treatment units are already on the market that operate without a FF or can be operated in a dedicated clinical FFF mode. Due to the convincing arguments of removing the FF, it is expected that more vendors will offer dedicated treatment units for advanced photon beam therapy in the near future. Several aspects related to standardization, dosimetry, treatment planning, and optimization need to be addressed in more detail in order to facilitate the clinical implementation of unflattened beams.
Technical Note: Determining regions of interest for CCD camera‐based fiber optic luminescence dosimetry by examining signal‐to‐noise ratio
Authors: Klein David M. , Therriault‐Proulx Francois , Archambault Louis , Briere Tina M. , Beaulieu Luc , Beddar A. Sam 
Published: March 2011

Purpose:The goal of this work was to develop a method for determining regions of interest (ROIs) based on signal‐to‐noise ratio (SNR) for the analysis of charge‐coupled device (CCD) images used in luminescence‐based radiation dosimetry.Methods:The ROI determination method was developed using images containing high‐and low‐intensity signals taken with a CCD‐based, fiber optic plastic scintillation detector system. A series of threshold intensity values was defined for each signal, and ROIs were fitted around the pixels that exceeded each threshold. The SNR for each ROI was calculated and the relationship between SNR and ROI area was examined.Results:The SNR was found to increase rapidly over small ROIs for both signal levels. After reaching a maximum, the SNR of the low‐intensity signal decreased steadily over larger ROIs, but the high‐intensity SNR did not decrease appreciably over the ROI sizes studied. The spatial extent of the normalized images showed intensity independence, suggesting that a fixed ROI is useful for varying signal levels.Conclusions:The method described here constitutes a simple yet effective method for defining ROIs based on SNR that could enhance the low‐level detection capabilities of CCD‐based luminescence dosimetry systems.