Full Head Research Articles

SU‐F‐J‐48: Effect of Scan Length On Magnitude of Imaging Dose in KV CBCT

Purpose:To study effect of scan length on magnitude of imaging dose deposition in Varian kV CBCT for head & neck and pelvis CBCT.Methods:To study effect of scan length we measured imaging dose at depth of 8 cm for head and neck Cone Beam Computed Tomography (CBCT) acquisition (X ray beam energy is used 100kV and 200 degree of gantry rotation) and at 16 cm depth for pelvis CBCT acquisition (X ray beam energy used is 125 kV and 360 degree of gantry rotation) in specially designed phantom. We used farmer chamber which was calibrated in kV X ray range for measurements .Dose was measured with default field size, and reducing field size along y direction to 10 cm and 5 cm.Results:As the energy of the beam decreases the scattered radiation increases and this contributes significantly to the dose deposited in the patient. By reducing the scan length to 10 Cm from default 20.6 cm we found a dose reduction of 14% for head and neck CBCT protocol and a reduction of 26% for pelvis CBCT protocol. Similarly for a scan length of 5cm compared to default the dose reduction in head and neck CBCT protocol is 36% while in the pelvis CBCT protocol the dose reduction is 50%.Conclusion:By limiting the scan length we can control the scatter radiation generated and hence the dose to the patient. However the variation in dose reduction for same length used in two protocols is because of the scan geometry. The pelvis CBCT protocol uses a full rotation and head and neck CBCT protocol uses partial rotation.

Individually customisable non-invasive head immobilisation system for non-human primates with an option for voluntary engagement

BackgroundHead immobilisation is often necessary for neuroscientific procedures. A number of Non-invasive Head Immobilisation Systems (NHIS) for monkeys are available, but the need remains for a feasible integrated system combining a broad range of essential features. New methodWe developed an individualised macaque NHIS addressing several animal welfare and scientific needs. The system comprises a customised-to-fit facemask that can be used separately or combined with a back piece to form a full-head helmet. The system permits presentation of visual and auditory stimuli during immobilisation and provides mouth access for reward. ResultsThe facemask was incorporated into an automated voluntary training system, allowing the animals to engage with it for increasing periods leading to full head immobilisation. We evaluated the system during performance on several auditory or visual behavioural tasks with testing sessions lasting 1.5–2h, used thermal imaging to monitor for and prevent pressure points, and measured head movement using MRI. Comparison with existing methodsA comprehensive evaluation of the system is provided in relation to several scientific and animal welfare requirements. Behavioural results were often comparable to those obtained with surgical implants. Cost–benefit analyses were conducted comparing the system with surgical options, highlighting the benefits of implementing the non-invasive option. ConclusionsThe system has a number of potential applications and could be an important tool in neuroscientific research, when direct access to the brain for neuronal recordings is not required, offering the opportunity to conduct non-invasive experiments while improving animal welfare and reducing reliance on surgically implanted head posts.

Editorial introductions

Current Opinion in Hematology was launched in 1994. It is part of a successful series of review journals whose unique format is designed to provide a systematic and critical assessment of the literature as presented in the many primary journals. The field of hematology is divided into nine sections that are reviewed once a year. Each section is assigned a Section Editor, a leading authority in the area, who identifies the most important topics at that time. Here we are pleased to introduce the Section Editors for this issue. SECTION EDITORS Mohandas NarlaMohandas NarlaDr Mohandas Narla is Vice President for Research and Director of the Lindsley F. Kimball Research Institute of New York Blood Center, USA. He received his doctoral degree from Washington University in St. Louis, USA, in Chemical Engineering. After completing post-doctoral training in hematology research with Dr Marcel Bessis, Institute of Cellular Pathology in Paris, France, he joined the faculty of the Department of Laboratory Medicine at University of California, USA, where he spent 13 years. In 1989, he moved to Lawrence Berkeley National Laboratory, University of California to head the Hematopoiesis group. During his 12 year tenure at the Berkeley Laboratory he also served as Interim Director of the Human Genome Project for three years. In 2001, he moved to the New York Blood Center, USA. Dr Mohandas’ scientific interests have long focused on red cell physiology and pathology. In particular, his efforts have contributed to improved understanding of the molecular and structural basis for red cell membrane disorders, developing detailed mechanistic insights into pathophysiology of thalassemias and sickle cell anemia, characterizing structural and functional changes induced in red cells by the malarial parasite, plasmodium falciparum. More recently his research efforts are focused on molecular understanding of normal and disordered erythropoiesis including Diamond-Blackfan Anemia and Myelodysplasia. Dr Mohandas served as a member of the National Institute of Health Hematology study section for 13 years and has been a member of numerous committees including the Executive committee of the American Society of Hematology. He served as Associate Editor of Blood from 2003–2012. He is currently Editor-in-Chief of Blood Cells, Molecules and Diseases and is on the Editorial Board of Journal of Biological Chemistry and Biochemistry. Edward F. PlowEdward F. PlowDr Plow received his PhD in Biochemistry in 1970. He joined The Scripps Research Institute, USA, as a postdoctoral fellow and remained at Scripps for 22 years, ultimately becoming a Full Member and Head of the Committee on Vascular Biology. In 1992, he relocated to the Cleveland Clinic, USA, to become Head of Research of the Joseph J. Jacobs Center for Thrombosis and Vascular Biology. He continues to hold this position and is Chair of the Department of Molecular Cardiology in the Lerner Research Institute of the Cleveland Clinic since 1994. Throughout his career, Dr Plow has performed research related to thrombosis, hemostasis and vascular biology. A primary area of his research interests has been platelets and the mechanisms of their adhesive and aggregation responses. This research has led him to investigate integrin structure and function on blood and vascular cells. A primary emphasis of his current research is the molecules and mechanisms governing integrin activation, where he has been instrumental in showing that the kindlin family is critical for integrin function in model cells, mice and humans. At the same time, Dr Plow has had a longstanding interest in the plasminogen system, with a particular emphasis on plasminogen and plasminogen receptors. The role of these molecules in cell adhesion, migration and inflammation has been emphasized. Recent studies by Dr Plow's group have touched into the areas of matrix biology and the roles of micro-RNAs in the pathogenesis of cardiovascular and neoplastic diseases. Dr Plow was an Established Investigator of the American Heart Association and the recipient of the Distinguished Career award of the ISTH and of the Platelet Colloquium. He has chaired two Gordon Research Conferences and organized the ATVB Meeting of the AHA. He has chaired the Council of the ISTH and the ATVB Council of the AHA. He has received an honorary degree from the Medical University of Lodz, Poland; a ZiQiang Professorship of Shanghai University, China, and was elected a Fellow of the American Association of the Advancement of Science. Dr Plow is the 2014 recipient of the International Society of Fibrinolysis and Proteolysis Prize.

Top-dressing nitrogen fertilizer rate contributes to decrease culm physical strength by reducing structural carbohydrate content in japonica rice

Lodging is an important factor limiting rice yield and quality by bending or breaking stem in japonica rice (Oryza sativa L.) production. The objectives of this study were to determine the mechanism of lodging resistance in japonica rice as affected by carbohydrate components, especially its related arrangement in culm tissue and response to top-dressing nitrogen (N) fertilizer. Field experiments were conducted in Danyang County, Jiangsu Province, China, by using two japonica rice varieties Wuyunjing 23 (lodging-resistance variety) and W3668 (lodging-susceptible variety) with three top-dressing N fertilizer rates (0, 135 and 270 kg N ha−1) in 2013 and 2014. Lodging related physical parameters, morphological characteristics and stem carbohydrate components were investigated at 30 d after full heading stage. Results showed that with increasing N fertilizer rates, the lodging rate and lodging index increased rapidly primarily due to significant reduction of breaking strength in two japonica rice varieties. Correlation analysis revealed that breaking strength was significantly and positively correlated with bending stress, but negatively correlated with section modulus, except for significant correlation at W3668 in 2014. Higher stem plumpness status and structural carbohydrate contents significantly enhanced stem stiffness, despite of lower non-structural carbohydrate. With higher N fertilizer rate, the culm wall thickness was almost identical, and culm diameter increased slightly. The structural carbohydrates, especially for lignin content in culm, reduced significantly under high N rate. Further histochemical staining analysis revealed that high N treatments decreased the lignin deposition rapidly in the sclerenchyma cells of mechanical tissue, large vascular bundle and small vascular bundle region, which were consistent with reduction of bending stress, especially for W3668 and thus, resulted in poor stem strength and higher lodging index. These results suggested that structural carbohydrate plays a vital role for improving stem strength in japonica rice. N rate decreased lodging resistance primarily due to poor stem stiffness, by reducing structural carbohydrate content and lignin deposition in the secondary cell wall of lower internode culm tissue.

Adaptive Skinning for Interactive Hair-Solid Simulation.

Reduced hair models have proven successful for interactively simulating a full head of hair strands, building upon a fundamental assumption that only a small set of guide hairs are needed for explicit simulation, and the rest of the hair move coherently and thus can be interpolated using guide hairs. Unfortunately, hair-solid interactions is a pathological case for traditional reduced hair models, as the motion coherence between hair strands can be arbitrarily broken by interacting with solids. In this paper, we propose an adaptive hair skinning method for interactive hair simulation with hair-solid collisions. We precompute many eligible sets of guide hairs and the corresponding interpolation relationships that are represented using a compact strand-based hair skinning model. At runtime, we simulate only guide hairs; for interpolating every other hair, we adaptively choose its guide hairs, taking into account motion coherence and potential hair-solid collisions. Further, we introduce a two-way collision correction algorithm to allow sparsely sampled guide hairs to resolve collisions with solids that can have small geometric features. Our method enables interactive simulation of more than 150 K hair strands interacting with complex solid objects, using 400 guide hairs. We demonstrate the efficiency and robustness of the method with various hairstyles and user-controlled arbitrary hair-solid interactions.

The inhibitory effects of potassium chloride versus potassium silicate application on 137Cs uptake by rice

After the accident at the Fukushima Dai-ichi Nuclear Power Plant owned by the Tokyo Electric Power Company on 11 March 2011, potassium fertilizer was applied to agricultural fields in the southern Tohoku and northern Kanto regions of Japan to reduce the uptake of radiocesium by crops. In this study, we examined the effects of two types of potassium fertilizers, potassium chloride (a readily available potassium fertilizer) and potassium silicate (a slow-release potassium fertilizer), as well as a split application of potassium, on the accumulation of 137Cs by rice plants in two pot experiments. The 137Cs concentrations in the brown rice and in the above-ground plants were significantly lower after potassium chloride application than after potassium silicate application. The potassium ion (K+) concentrations in soil solutions sampled 9 and 21 d after transplanting were significantly higher for the potassium chloride application than for the potassium silicate application. The K+ concentrations in soil solutions observed in the application of potassium silicate were similar to those in the treatment when no potassium was applied. This finding indicates that the application of potassium silicate did not sufficiently increase the available K+ for rice plants in the soil, which led to a greater uptake of 137Cs after the potassium silicate application than after the application of potassium chloride. The 137Cs concentration in brown rice was higher in the split application of potassium fertilizer with the second application at the full heading stage than that without split application and the split application with the second application before heading.

Television Tip Overs and Head Traumas in Childhood: Results of 36 Children from a Reference Center in Central Anatolia, Turkey.

Television tip overs and head traumas in children showed an increase in the recent years in Turkey and throughout the world. In this study, the injury types, the surgical interventions and the children exposed to head trauma due to an accident caused by a falling television were investigated retrospectively. Some cautions were suggested in order to prevent these injuries. The gender, age, Pediatric Glasgow Coma Scale (PGCS) score, radiologic findings, the need for intensive care unit, the time period spent in the hospital, the applied surgical treatments, the accompanied treatment and pathology of 36 children who were treated in the department of neurosurgery at Erciyes University School of Medicine were evaluated. Eighteen of the patients were male and 18 were female. The number of cases younger than 3 years was 21 while the number of cases over the age of 3 years was 15. Thirty-two of the cases had full head trauma. Three female patients died. The mean PGCS score at admission was 12.7. While surgical treatment was applied to four of the patients in our department, facial nerve exploration was performed in the Ear Nose and Throat Department to the patient who suffered facial nerve damage. Each year, many children are injured or even die due to this trauma that can be easily prevented. The parents, television producers, doctors, health personnel, academic institutions, governments, legislators, national and international organizations are responsible for this trauma.

Positional difference in potassium concentration as diagnostic index relating to plant K status and yield level in rice (Oryza sativa L.)

ABSTRACTPlant tissue testing is used as a guide for rice (Oryza sativa L.) fertilization and has been extensively used in the diagnosis of potassium (K) deficiency. However, little attention has been paid to the variation in the diagnostic index of K status in different parts of the rice plant. Here, we assessed the feasibility by testing K concentrations of whole plants, leaf blades and leaf sheaths to develop a suitable diagnostic index of plant K status and yield level in rice under different K application rates. The results showed that this research could satisfy the requirements of K status diagnosis, based on the quadratic-plus-plateau relationship between K application rates and grain yield. The K concentrations of the leaf blades and leaf sheaths on the main stem showed differences based on position. Leaf blade K concentrations significantly decreased from the top of the plant to the bottom in the effective tillering and jointing stages. Conversely, K concentrations in the lower leaf blades exceeded those in the upper leaf blades in the booting and full heading stages. K concentrations in the leaf sheath were significantly reduced with declining leaf position except during the jointing stage under high K treatments. Leaf sheath/leaf blade K concentration ratios increased significantly more in lower tissues than in upper plant tissues. Correlation analysis showed that the K concentrations of all sampled plant tissues were positively correlated to plant K uptake and grain yield. However, K concentrations of the whole plant were more useful as a diagnostic index at the effective tillering stage than at other growth stages. Leaf sheaths in lower positions were preferable to upper leaf sheaths and all leaf blades for evaluating plant K status, although their K concentrations were greatly influenced by plant growth stage. Furthermore, this study demonstrated that the ratio between the K concentrations of the first and fourth leaf blades (LBKR1/4) was grouped into significantly exponential curves (P < 0.01) to describe the relationship between plant K uptake and relative grain yield. Thus, LBKR1/4 could be an ideal indicator of rice plant K status and yield level, as it eliminated the effects of plant growth stage.

Parallel Solver for Diffuse Optical Tomography on Realistic Head Models With Scattering and Clear Regions.

Diffuse optical tomography is an imaging technique, based on evaluation of how light propagates within the human head to obtain the functional information about the brain. Precision in reconstructing such an optical properties map is highly affected by the accuracy of the light propagation model implemented, which needs to take into account the presence of clear and scattering tissues. We present a numerical solver based on the radiosity-diffusion model, integrating the anatomical information provided by a structural MRI. The solver is designed to run on parallel heterogeneous platforms based on multiple GPUs and CPUs. We demonstrate how the solver provides a 7 times speed-up over an isotropic-scattered parallel Monte Carlo engine based on a radiative transport equation for a domain composed of 2 million voxels, along with a significant improvement in accuracy. The speed-up greatly increases for larger domains, allowing us to compute the light distribution of a full human head ( ≈ 3 million voxels) in 116 s for the platform used.

Water Selective Imaging and bSSFP Banding Artifact Correction in Humans and Small Animals at 3T and 7T, Respectively.

IntroductionThe purpose of this paper is to develop an easy method to generate both fat signal and banding artifact free 3D balanced Steady State Free Precession (bSSFP) images at high magnetic field.MethodsIn order to suppress fat signal and bSSFP banding artifacts, two or four images were acquired with the excitation frequency of the water-selective binomial radiofrequency pulse set On Resonance or shifted by a maximum of 3/4TR. Mice and human volunteers were imaged at 7T and 3T, respectively to perform whole-body and musculoskeletal imaging. “Sum-Of-Square” reconstruction was performed and combined or not with parallel imaging.ResultsThe frequency selectivity of 1-2-3-2-1 or 1-3-3-1 binomial pulses was preserved after (3/4TR) frequency shifting. Consequently, whole body small animal 3D imaging was performed at 7T and enabled visualization of small structures within adipose tissue like lymph nodes. In parallel, this method allowed 3D musculoskeletal imaging in humans with high spatial resolution at 3T. The combination with parallel imaging allowed the acquisition of knee images with ~500μm resolution images in less than 2min. In addition, ankles, full head coverage and legs of volunteers were imaged, demonstrating the possible application of the method also for large FOV.ConclusionIn conclusion, this robust method can be applied in small animals and humans at high magnetic fields. The high SNR and tissue contrast obtained in short acquisition times allows to prescribe bSSFP sequence for several preclinical and clinical applications.

Playing Pregnancy: The Ludification and Gamification of Expectant Motherhood in Smartphone Apps

Like other forms of embodiment, pregnancy has increasingly become subject to representation and interpretation via digital technologies. Pregnancy and the unborn entity were largely private, and few people beyond the pregnant women herself had access to the foetus growing within her (Duden). Now pregnant and foetal bodies have become open to public portrayal and display (Lupton The Social Worlds of the Unborn). A plethora of online materials – websites depicting the unborn entity from the moment of conception, amateur YouTube videos of births, social media postings of ultrasounds and self-taken photos (‘selfies’) showing changes in pregnant bellies, and so on – now ensure the documentation of pregnant and unborn bodies in extensive detail, rendering them open to other people’s scrutiny. Other recent digital technologies directed at pregnancy include mobile software applications, or ‘apps’. In this article, we draw on our study involving a critical discourse analysis of a corpus of pregnancy-related apps offered in the two major app stores. In so doing, we discuss the ways in which pregnancy-related apps portray pregnant and unborn bodies. We place a particular focus on the ludification and gamification strategies employed to position pregnancy as a playful, creative and fulfilling experience that is frequently focused on consumption. As we will demonstrate, these strategies have wider implications for concepts of pregnant and foetal embodiment and subjectivity. It is important here to make a distinction between ludification and gamification. Ludification is a broader term than gamification. It is used in the academic literature on gaming (sometimes referred to as ‘ludology’) to refer to elements of games reaching into other aspects of life beyond leisure pursuits (Frissen et al. Playful Identities: The Ludification of Digital Media Cultures; Raessens). Frissen et al. (Frissen et al. "Homo Ludens 2.0: Play, Media and Identity") for example, claim that even serious pursuits such as work, politics, education and warfare have been subjected to ludification. They note that digital technologies in general tend to incorporate ludic dimensions. Gamification has been described as ‘the use of game design elements in non-game contexts’ (Deterding et al. 9). The term originated in the digital media industry to describe the incorporation of features into digital technologies that not explicitly designed as games, such as competition, badges, rewards and fun that engaged and motivated users to make them more enjoyable to use. Gamification is now often used in literatures on marketing strategies, persuasive computing or behaviour modification. It is an important element of ‘nudge’, an approach to behaviour change that involves persuasion over coercion (Jones, Pykett and Whitehead). Gamification thus differs from ludification in that the former involves applying ludic principles for reasons other than the pleasures of enjoying the game for their own sake, often to achieve objectives set by actors and agencies other than the gamer. Indeed, this is why gamification software has been described by Bogost (Bogost) as ‘exploitationware’.

Premature heading and yield losses caused by prolonged seedling age in double cropping rice

Increasing the frequency of harvests through multiple cropping is a promising way to increase global food production. In double cropping rice, prolonged seedling age leads to yield losses; however, the underlying mechanisms that cause yield reduction are poorly understood. In this study, field experiments were conducted in the early and late growing seasons of 2013 and 2014 in Zhangbang village, Wuxue county, Hubei province, China. Two seedling age treatments (control and prolonged) were studied in a randomized complete block design with four replications. Compared to the control seedling age treatment of 30–35 days, grain yield was reduced in the prolonged seedling age treatment of 40–46 days by 17.9% in the early growing season of 2013 and 2014, and 18.2% in the late growing season of 2014. Yield loss resulted from reduced biomass and grain weight. Premature heading was observed in the prolonged seedling age treatment in both growing seasons; main stem heading occurred 8–13 days earlier and tiller stem heading about 8 days later compared to the control seedling age treatment. Full heading was completed within 12 days in the control seedling age treatment, while in the prolonged seedling age treatment within 27–33 days. In the prolonged seedling age treatment, yield loss resulted from the reduced grain yield of both stem types, one bearing premature-heading panicles and the other bearing normal-heading panicles. Single-stem measurements, including biomass, grain weight, plant height, leaf area, length and width of flag leaf, and degeneration of panicle branches and spikelets, significantly changed in both stem types. Overall, it is important to prevent prolonged seedling age in double cropping rice mainly through the reasonable arrangement of crops in a rotation system.

Irrigation with oxygen-nanobubble water can reduce methane emission and arsenic dissolution in a flooded rice paddy

A remarkable feature of nanobubbles (<10–6 m in diameter) is their long lifetime in water. Supplying oxygen-nanobubbles (NBs) to continuously flooded paddy soil may retard the development of reductive conditions, thereby reducing the emission of methane (CH4), a potent greenhouse gas, and dissolution of arsenic, an environmental load. We tested this hypothesis by performing a pot experiment and measuring redox-related variables. The NBs were introduced into control water (with properties similar to those of river water) using a commercially available generator. Rice (Oryza sativa L.) growth did not differ between plants irrigated with NB water and those irrigated with control water, but NB water significantly (p < 0.05) reduced cumulative CH4 emission during the rice-growing season by 21%. The amounts of iron, manganese, and arsenic that leached into the drainage water before full rice heading were also reduced by the NB water. Regardless of the water type, weekly-measured CH4 flux was linearly correlated with the leached iron concentration during the rice-growing season (r = 0.74, p < 0.001). At the end of the experiment, the NB water significantly lowered the soil pH in the 0–5 cm layer, probably because of the raised redox potential. The population of methanogenic Archaea (mcrA copy number) in the 0–5 cm layer was significantly increased by the NB water, but we found no correlation between the mcrA copy number and the cumulative CH4 emission (r = –0.08, p = 0.85). In pots without rice plants, soil reduction was not enhanced, regardless of the water type. The results indicate that NB water reduced CH4 emission and arsenic dissolution through an oxidative shift of the redox conditions in the flooded soil. We propose the use of NB water as a tool for controlling redox conditions in flooded paddy soils.

Efficient estimation of tissue thicknesses using sparse approximation for Gaussian processes.

Highly accurate localization of the human skull is vital in cranial radiotherapy. Marker-less optical head tracking provides a fast and accurate way to monitor this motion. Recent research has given evidence that marker-less tracking of the forehead benefits from tissue thickness information in addition to the 3D surface geometry. Using Gaussian Processes (GPs) tissue thickness is determined from optical backscatter of a sweeping laser. However, the computational complexity of the GPs scales cubically with the number of training samples. A full head scan contains 1024 points, whereas scans from several perspectives may be required for a comprehensive model for each subject. In five subjects, we thus evaluate sparse approximation methods to reduce the computational effort. We found a better - computation time versus root mean square error (RMSE) - tradeoff for a simple subset of data (SoD) technique. The increase of RMSE when dropping data was not found steep enough to justify the computational overhead of a better approximation by inducing point methods (namely FITC). Promising results were, however, obtained when clustering the training data before selecting the subset.

Discourse accessibility constraints in children's processing of object relative clauses.

Children’s poor performance on object relative clauses has been explained in terms of intervention locality. This approach predicts that object relatives with a full DP head and an embedded pronominal subject are easier than object relatives in which both the head noun and the embedded subject are full DPs. This prediction is shared by other accounts formulated to explain processing mechanisms. We conducted a visual-world study designed to test the off-line comprehension and on-line processing of object relatives in German-speaking 5-year-olds. Children were tested on three types of object relatives, all having a full DP head noun and differing with respect to the type of nominal phrase that appeared in the embedded subject position: another full DP, a 1st- or a 3rd-person pronoun. Grammatical skills and memory capacity were also assessed in order to see whether and how they affect children’s performance. Most accurately processed were object relatives with 1st-person pronoun, independently of children’s language and memory skills. Performance on object relatives with two full DPs was overall more accurate than on object relatives with 3rd-person pronoun. In the former condition, children with stronger grammatical skills accurately processed the structure and their memory abilities determined how fast they were; in the latter condition, children only processed accurately the structure if they were strong both in their grammatical skills and in their memory capacity. The results are discussed in the light of accounts that predict different pronoun effects like the ones we find, which depend on the referential properties of the pronouns. We then discuss which role language and memory abilities might have in processing object relatives with various embedded nominal phrases.

SU‐E‐J‐05: Use of a 6D Couch for Real‐Time Full Translational and Rotational Head Motion Correction During Stereotactic Radiosurgery: A Feasibility Study

Purpose:This work presents a methodology for correcting full translational and rotational head motion deviations during frameless image‐guided stereotactic radiosurgery (SRS) procedures with a robotic 6D couch. The main objective is to design control algorithms which optimize the correction motion of a 6D couch when sub‐millimeter/sub‐degree accuracy requirements are necessary in SRS.Methods:The system includes 6D position tracking and a 6D couch with three serially connected platforms. The bottom platform controls yaw compensation (around the z axis), the middle one generates full 3D translational motion, and the top platform controls both pitch (around X) and roll (around Y) motion with two linear actuators. Based on the 6D position of the head and the couch at each moment, the desired 6D couch position for correction is calculated, with the required 6 actuator outputs computed by an inverse algorithm accordingly. To minimize their responsive motion, the actuators take action only after the head position deviates beyond certain predetermined thresholds, and for each action the head is returned to the center of desired 6D treatment position.Results:With computer simulation, head motion of an SRS patient was modeled and the simulated couch was used to compensate for this motion in real‐time. For a 15‐minute test with a 0.3 mm and 0.15 degree target position tolerance, the corrected 6D head position was within tolerance over 99.5% of the time. The actuators moved approximately 80 times during the simulation, and the total actuator motion for translational correction was around 205 mm.Conclusion:We investigated a control approach for full translational and rotational head motion correction with a 6D couch. The simulations demonstrated that with moderate correction motion of a 6D couch, the control performance meets real‐time submillimeter and sub‐degree accuracy requirement of frameless SRS.The research is funded by the American Cancer Society (ACS) grant. The grant name is: Frameless SRS Based on Robotic Head Motion Cancellation. The grant number is: RSG‐13‐313‐01‐CCE

SU‐E‐T‐08: A Beam Source Model for Monte Carlo Simulations of a Double‐Scattering Proton Beam Delivery System Using Beam Current Modulation

Purpose:To reconstruct phase‐space information upstream of patient specific collimators for Monte Carlo simulations using only radiotherapy planning system data.Methods:The proton energies are calculated based on residual ranges, e.g., sum of prescribed ranges in a patient and SSD. The Kapchinskij and Vladimirskij (KV) distribution was applied to sample proton's x‐y positions and momentum direction and the beam shape was assumed to be a circle. Free parameters, e.g., the initial energy spread and the emittance of KV distribution were estimated from the benchmarking with commissioning data in a commercial treatment planning system for an operational proton therapy center. The number of histories, which defines the height of individual pristine Bragg peaks (BP) of Spread‐out Bragg peak (SOBP), are weighted based on beam current modulation and a correction factor is applied to take into account the fluence reduction as the residual range decreases due to the rotation of the range modulator wheel. The timedependent behaviors, e.g., the changes of the residual range and histories per a pristine BP, are realized by utilizing TOPAS (Tool for Particle Simulation).Results:Benchmarking simulations for selected SOBPs ranging 7.5 cm to 15.5 cm matched within 2 mm in range and up to 5 mm in SOBP width against measurement data in water phantom. We found this model tends to underestimate entrance dose by about 5 % in comparison to measurement. This was attributed to the situation that the energy distribution used in the model was limited in its granularity at the limit of single energy spectrum for the narrow angle modulator steps used in the proximal pull back region of the SOBPs.Conclusion:Within these limitations the source modeling method proved itself an acceptable alternative of a full treatment head simulation when the machine geometry and materials information are not available.

SU-D-213-01: Transparent Photon Detector For The Online Monitoring Of IMRT Beams

Purpose: An innovative Transparent Detector for Radiotherapy (TraDeRa) has been developed. The detector aims at real-time monitoring of modulated beam ahead of the patient during delivery sessions, with a field cover up to 40×40 cm {sup 2}. Methods: TraDeRa consists in a pixelated matrix of ionization chambers with a patented electrodes design. An in-house designed specific integrated circuit allows to extract the signal and provides a real-time map of beam intensity and shape, at the linac pulse-scale. The measurements under irradiation are made with a 6 MV clinical X-Ray beam. Dose calculations are performed with the Monte Carlo code PENELOPE, modeling the full accelerator head and the TraDeRa detector. Results: A 2 % attenuation of the beam was measured in the presence of TraDeRa and the PENELOPE dosimetric study showed no significant modification of the photon beam properties. TraDeRa detects error leaf position as small as 1 mm compared to a reference field, for both static and modulated fields. In addition, measurements are accurate over a large dynamic range from low intensity signals, as inter-leaves leaks, to very high intensities as obtained on the medical line of the European Synchrotron Radiation Facility. The detector is fully operational for conventional andmore » high dose rate beams as FFF modes (up to 2400 MU/min). Conclusion: The current version of TraDeRa shows promising results for IMRT quality assurance (QA), allowing pulse-scale monitoring of the beam and high sensitivity for errors detection. The attenuation is small enough not to hinder the irradiation while keeping the beam upstream of the patient under constant control. A final prototype under development will include 1600 independent electrodes, half of them with a high resolution centered on the beam axis. This compact detector provides an independent set of measurements for a better QA. Funding support : This work was supported by the LABEX PRIMES (ANR-11-LABX-0063) of Universite de Lyon, within the program “Investissements d’Avenir” (ANR-11-IDEX-0007) operated by the French National Research Agency (ANR) and within the project “INSPIRA” operated by the OSEO institution.« less

Determination of rice panicle numbers during heading by multi-angle imaging

Plant phenomics has the potential to accelerate progress in understanding gene functions and environmental responses. Progress has been made in automating high-throughput plant phenotyping. However, few studies have investigated automated rice panicle counting. This paper describes a novel method for automatically and nonintrusively determining rice panicle numbers during the full heading stage by analyzing color images of rice plants taken from multiple angles. Pot-grown rice plants were transferred via an industrial conveyer to an imaging chamber. Color images from different angles were automatically acquired as a turntable rotated the plant. The images were then analyzed and the panicle number of each plant was determined. The image analysis pipeline consisted of extracting the i2 plane from the original color image, segmenting the image, discriminating the panicles from the rest of the plant using an artificial neural network, and calculating the panicle number in the current image. The panicle number of the plant was taken as the maximum of the panicle numbers extracted from all 12 multi-angle images. A total of 105 rice plants during the full heading stage were examined to test the performance of the method. The mean absolute error of the manual and automatic count was 0.5, with 95.3% of the plants yielding absolute errors within ±1. The method will be useful for evaluating rice panicles and will serve as an important supplementary method for high-throughput rice phenotyping.

Abscisic acid and the key enzymes and genes in sucrose-to-starch conversion in rice spikelets in response to soil drying during grain filling.

Abscisic acid mediates the effect of post-anthesis soil drying on grain filling through regulating the activities of key enzymes and expressions of genes involved in sucrose-to-starch conversion in rice spikelets. This study investigated if abscisic acid (ABA) would mediate the effect of post-anthesis soil drying on grain filling through regulating the key enzymes in sucrose-to-starch conversion in rice (Oryza sativa L.) spikelets. Two rice cultivars were field-grown. Three treatments, well-watered (WW), moderate soil drying (MD), and severe soil drying (SD), were imposed from 6 days after full heading until maturity. When compared with those under the WW, grain filling rate, grain weight, and sink activity, in terms of the activities and gene expression levels of sucrose synthase, ADP glucose pyrophosphorylase, starch synthase, and starch branching enzyme, in inferior spikelets were substantially increased under the MD, whereas they were markedly decreased in both superior and inferior spikelets under the SD. The two cultivars showed the same tendencies. Both MD and SD increased ABA content and expression levels of its biosynthesis genes in spikelets, with more increase under the SD than the MD. ABA content was significantly correlated with grain filling rate and sink activities under both WW and MD, while the correlations were not significant under the SD. Application of a low concentration ABA to WW plants imitated the results under the MD, and applying with a high concentration ABA showed the effect of the SD. The results suggest that ABA plays a vital role in grain filling through regulating sink activity and functions in a dose-dependent manner. An elevated ABA level under the MD enhances, whereas a too high level of ABA under the SD decreases, sink activity.