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PURPOSE: To improve image quality and CT number accuracy of daily cone-beam computed tomography (CBCT) through a deep-learning methodology with Generative Adversarial Network. METHODS: 150 paired pelvic CT and CBCT scans were used for model training and validation. An unsupervised deep-learning method, 2.5D pixel-to-pixel generative adversarial network (GAN) model with feature mapping was proposed. A total of 12000 slice pairs of CT and CBCT were used for model training, while 10-cross validation was applied to verify model robustness. Paired CT-CBCT scans from an additional 15 pelvic patients and 10 head-and-neck (HN) patients with CBCT images collected at a different machine were used for independent testing purpose. Besides the proposed method above, other network architectures were also tested as: 2D vs. 2.5D; GAN model with vs. without feature mapping; GAN model with vs. without additional perceptual loss; and previously reported models as U-net and cycleGAN with or without identity loss. Image quality of deep-learning generated synthetic CT (sCT) images were quantitatively compared against the reference CT (rCT) image using mean absolute error (MAE) of Hounsfield units (HU) and peak signal-to-noise ratio (PSNR). The dosimetric calculation accuracy was further evaluated with both photon and proton beams. RESULTS: The deep-learning generated synthetic CTs (sCT) showed improved image quality with reduced artifact distortion and improved soft tissue contrast. The proposed algorithm of 2.5 Pix2pix GAN with feature matching (FM) was shown to be the best model among all tested methods producing the highest PSNR and the lowest MAE to reference CT (rCT). The dose distribution demonstrated a high accuracy in the scope of photon based planning, yet more work is needed for proton based treatment. Once the model was trained, it took 11–12 ms to process one slice, and could generate a 3D-volume of dCBCT (80 slices) in less than a second using a NVIDIA GeForce GTX Titan X GPU (12GB, Maxwell architecture). CONCLUSION: The proposed deep-learning algorithm is promising to improve CBCT image quality in an efficient way, thus has a potential to support online CBCT-based adaptive radiotherapy.

Importance A high prevalence of retinal abnormalities have been reported in congenital heart disease (CHD), but quantitative analysis of retinal vasculature is scarce. Optical coherence tomography angiography (OCTA) is a noninvasive method to quantitatively assess the retinal microvasculature. Background To investigate the retinal microvasculature changes in CHD patients by using OCTA. Design Cross‐sectional study. Participants A total of 158 participants including 57 cyanotic CHD (CCHD) patients, 60 acyanotic CHD (ACHD) patients and 41 control subjects were included. Methods All participants underwent a comprehensive ophthalmologic examination, including refraction measurement, intraocular pressure measurement and OCTA. Main Outcome Measures Vessel density (VD) was measured within the radial peripapillary capillary (RPC), superficial capillary plexus (SCP) and deep capillary plexus (DCP) of the macula. Results CCHD patients had significantly lower VD in the RPC, SCP and DCP (all P

Purpose The on-board flat-panel cone-beam computed tomography (CBCT) lacks molecular/functional information for current online image-guided radiation therapy (IGRT). It might not be adequate for adaptive radiation therapy (ART), particularly for biologically guided tumor delineation and targeting which might be shifted and/or distorted during the course of RT. A linear accelerator (Linac) gantry-mounted on-board imager (OBI) was proposed using a single photon counting detector (PCD) panel to achieve single photon emission computed tomography (SPECT), energy-resolved spectral CT, and conventional CBCT triple on-board imaging, which might facilitate online ART with an addition of volumetric molecular/functional imaging information. Methods The system was designed and evaluated in the GATE Monte Carlo platform. The OBI system including a kV-beam source and a pixelated cadmium zinc telluride (CZT) detector panel mounted on a medical Linac orthogonally to the MV beam direction was designed to obtain online CBCT, spectral CT, and SPECT tri-modal imaging of patients in the treatment room. The spatial resolutions of the OBI system were determined by imaging simulated phantoms. The CBCT imaging was evaluated by a simulated contrast phantom. A PMMA phantom containing gadolinium was imaged to demonstrate quantitative imaging of spectral-CT/CBCT of the system. The capability of tri-modal imaging of the OBI was demonstrated using three different spectral CT imaging methods to differentiate gadolinium, gold, calcium within simulated PMMA and the SPECT to image radioactive 99m Tc distribution. The dual-isotope SPECT imaging of the system was also evaluated by imaging a phantom containing 99m Tc and 123 I. The radiotherapy-related parameters of iodine contrast fraction and virtual non-contrast (VNC) tissue electron density in the Kidney1 inserts of a simulated phantom were decomposed using the Bayesian eigentissue decomposition method for contrast-enhanced CBCT/spectral-CT of the OBI in a single scan. Results The spatial resolutions of CBCT and SPECT of the OBI were determined to be 15.1 lp/cm at 10% MTF and 4.8-12 mm for radii of rotation of 10-40 cm, respectively. In CBCT image of the contrast phantom, most of the soft-tissue inserts were visible with sufficient spatial structure details. As compared to the CBCT image of gadolinium, the spectral CT image provided higher image contrasts. Calcium, gadolinium, and gold were separated well by using the spectral CT material imaging methods. The reconstructed distribution of 99m Tc agreed with the spatial position within the phantom. The two isotopes were separated from each other in dual-isotope SPECT imaging of the OBI. The iodine fractions and the VNC electron densities were estimated in the iodine-enhanced Kidney1 tissue inserts with reasonable RMS errors. The main procedures of the tri-modal imaging guided online ART workflow were presented with new functional features included. Conclusions Using a single photon counting CZT detector panel, an on-board SPECT, spectral CT, and CBCT tri-modal imaging could be realized in Linacs. With the added online molecular/functional imaging obtained from the new OBI for the online ART proposed, the accuracy of radiation treatment delivery could be further improved.

Purpose Dual-energy CT (DECT) enhances tissue characterization because of its basis material decomposition capability. In addition to conventional two-material decomposition from DECT measurements, multimaterial decomposition (MMD) is required in many clinical applications. To solve the ill-posed problem of reconstructing multi-material images from dual-energy measurements, additional constraints are incorporated into the formulation, including volume and mass conservation and the assumptions that there are at most three materials in each pixel and various material types among pixels. The recently proposed flexible image-domain MMD method decomposes pixels sequentially into multiple basis materials using a direct inversion scheme which leads to magnified noise in the material images. In this paper, we propose a statistical image-domain MMD method for DECT to suppress the noise. Methods The proposed method applies penalized weighted least-square (PWLS) reconstruction with a negative log-likelihood term and edge-preserving regularization for each material. The statistical weight is determined by a data-based method accounting for the noise variance of high- and low-energy CT images. We apply the optimization transfer principles to design a serial of pixel-wise separable quadratic surrogates (PWSQS) functions which monotonically decrease the cost function. The separability in each pixel enables the simultaneous update of all pixels. Results The proposed method is evaluated on a digital phantom, Catphan©600 phantom and three patients (pelvis, head, and thigh). We also implement the direct inversion and low-pass filtration methods for a comparison purpose. Compared with the direct inversion method, the proposed method reduces noise standard deviation (STD) in soft tissue by 95.35% in the digital phantom study, by 88.01% in the Catphan©600 phantom study, by 92.45% in the pelvis patient study, by 60.21% in the head patient study, and by 81.22% in the thigh patient study, respectively. The overall volume fraction accuracy is improved by around 6.85%. Compared with the low-pass filtration method, the root-mean-square percentage error (RMSE(%)) of electron densities in the Catphan©600 phantom is decreased by 20.89%. As modulation transfer function (MTF) magnitude decreased to 50%, the proposed method increases the spatial resolution by an overall factor of 1.64 on the digital phantom, and 2.16 on the Catphan©600 phantom. The overall volume fraction accuracy is increased by 6.15%. Conclusions We proposed a statistical image-domain MMD method using DECT measurements. The method successfully suppresses the magnified noise while faithfully retaining the quantification accuracy and anatomical structure in the decomposed material images. The proposed method is practical and promising for advanced clinical applications using DECT imaging.

BACKGROUND Pineapple has a delicious taste and good health benefits. Bioactive polysaccharides are important components of pineapple that might contribute to its health benefits. Since little structural information on these polysaccharides is currently available, the aim of this study was to investigate their structural characteristics and bioactivities. RESULTS The polysaccharides of pineapple pulp were fractionated into three fractions (PAPs 1–3) by anion exchange chromatography. Their structural characteristics were first identified, including molecular weights and glycosidic linkages. The monosaccharide compositions were revealed as PAP 1 (Ara, Xyl, Man, Glc and Gal), PAP 2 (Rha, Ara, Xyl, Man, Glc and Gal) and PAP 3 (Rha, Ara, Xyl, Man and Gal). Nuclear magnetic resonance (NMR) spectra suggested that PAP 2 had a backbone of 4)-α-d-Manp-(1 2,4)-α-d-Manp-(1 with branches attached to O-4 of Manp. The NMR data of α-l-Araf-(1, 3)-α-l-Araf-(1, 4)-β-d-Galp-(1 and 4)-α-d-GalpAMe-(1 were assigned. PAPs 1 and 2 showed significant antitumor cell proliferation activities against breast carcinoma cell line and strong antioxidant activities. CONCLUSION The above findings indicated that PAPs 1–3 contributed much to the health benefits of pineapple. They could be used as health-beneficial food additives in functional foods. © 2015 Society of Chemical Industry

Background The purpose of this study was to evaluate the advantages of exenatide treatment on obesity and non-alcoholic fatty liver disease (NAFLD) with elevated liver enzymes in patients with type 2 diabetes (T2D). Methods A total of 60 newly diagnosed patients with obesity, NAFLD with elevated liver enzymes and T2D were included in the study. The patients were randomly divided into two groups. The exenatide treatment group (n = 30) were treated with exenatide and insulin glargine, and the intensive insulin therapy group (n = 30) were treated with insulin aspart and insulin glargine for 12 weeks. Selected clinical characteristics were determined, and ultrasonography was performed at both baseline and 12 weeks following treatment. Results At baseline, the clinical characteristics were matched between the two groups. After 12 weeks, fasting blood glucose (FBG), postprandial blood glucose (PBG), glycosylated haemoglobin (HbA1c), total cholesterol (TC), triglyceride (TG) and total bilirubin levels were significantly decreased in the two groups (p

A micropayment scheme provides a secure and efficient solution for electronic payment environments that require frequent transactions with nominal fees. It is particularly suitable for mobile applications in which a customer is charged for either time spent or data volume transferred. Most proposed micropayment schemes are based on "PayWord" by Rivest and Shamir. The security and efficiency of a micropayment scheme can be ensured by adopting the hash chain technique. Recent research on micropayment has introduced additional properties such as user anonymity and fairness. However, the existing schemes may lose efficiency and some of the original desirable properties of PayWord while achieving new ones. We propose an anonymous fair offline micropayment scheme that satisfies user anonymity and fairness and retains the efficiency and properties of PayWord, such as offline broker. A user can make multiple purchases from different vendors without interacting with the broker again. PayWord's postpaid mechanism is adopted in order to make our scheme more attractive to users. To the best of our knowledge, this is the first micropayment scheme to simultaneously offer the aforementioned properties. Copyright © 2012 John Wiley & Sons, Ltd.

The mechanism and dynamics of the H + CD(4) -> CD(3) + HD (I) and H + CH(4) -> CH(3) + H(2) (II) reactions have been investigated by electronic structure methods. The minimum-energy path and vibrational frequencies along the intrinsic reaction coordinate are calculated at MP2/cc-pVDZ level. Energy distributions of the products are also obtained by the direct classical trajectory calculations at the MP2/cc-pVDZ level. It is found that most of the available energy appears as product translational energy, and very little of the available energy is partitioned into internal excitation of the HD (H(2)) product for reaction I (II), which is in agreement with the experimental evidence. The results indicate that the experimental results could be reproduced by the direct MP2 molecular dynamics calculations. The rotational state distributions of the products show the HD (H(2)) products are formed with lower rotational quantum numbers than the CD(3) (CH(3)) products. (C) 2011 Wiley Periodicals, Inc. Int J Quantum Chem 111: 4433-4442, 2011

UNLABELLED This study measured the potentiation effects of plyometric training [normalized electromyography (EMG) in triceps surae, stiffness and elastic energy utilization of the Achilles tendon] and investigated the correlations between these effects and performances [voluntary electromechanical delay (EMD) and jump height]. Twenty-one subjects were randomly assigned either to the control group (10 subjects: age 22.3+/-1.6 years) or to a training group (11 subjects: age 22.1+/-1.6 years) that performed 8 weeks of plyometric training. RESULTS As compared with the performances before training, normalized EMG in the soleus were significantly (P

The present work employs the complete energy matrices for a d(8) configuration ion in a D(2h) symmetry ligand field at first time to study the relationship between electron paramagnetic resonance (EPR) spectra and local structure of (NiF(6))(4-) coordination complex in Ni(2+):ZnF(2), NiF(2), and Ni(2+):MgF(2) systems, respectively. The crystal field effect on the local structure of the three systems is investigated contrastively by calculating the values of vertical bar partial derivative D'/partial derivative theta vertical bar and vertical bar partial derivative E'/partial derivative theta vertical bar around the (NiF(6))(4-) coordination complex. Moreover, the theoretical values of the g factors of Ni(2+):ZnF(2), NiF(2), and Ni(2+):MgF(2) systems are reported. Simultaneously, the calculated energy levels are in good agreement with the experimental absorption spectra. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

The electron paramagnetic resonance (EPR) parameters and local structure of the octahedral [Cr(H(2)O)(6)](3+) complex for Cr(3+) doped in GASH and AlCl(3) center dot 6H(2)O crystals with trigonal symmetry have been studied on the basis of the 120 x 120 complete energy matrices, respectively. By simulating the EPR and optical spectra, the local structure distortion parameters are determined in the temperature range of 4.2-297 K. The calculated results show that the local structure of [Cr(H(2)O)(6)](3+) octahedron exhibits an elongated distortion and the value of distortion depends on the temperature. Furthermore, the interrelation between the g-factors and orbit-reduction factor k has been studied, and the influence of the local structure on the EPR parameters has also been discussed. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Purpose. To examine the hemiplegic shoulders for soft-tissue injury by musculoskeletal sonography and to determine the relationship between the motor functions of the upper extremity and these injuries, which play an important role in hemiplegic shoulder pain and may impede rehabilitation. Methods. The following characteristics of 34 acute stroke patients were recorded: age, gender, height, body weight, side of hemiplegia, type and duration of stroke, Brunnstrom stage, subluxation, and degree of spasticity of the upper extremity. On the basis of the Brunnstrom stage, the patients were divided into 2 groups. Patients with stages I, II, or III were categorized under the lower Brunnstrom stage (LBS) group (n = 21), and those with stages IV, V, or VI were allocated to the higher Brunnstrom stage (HBS) group (n = 13). Both shoulders of each patient were examined by musculoskeletal sonography with a 5–10-MHz linear transducer on 2 separate occasions (i.e., at admission and 2 weeks after rehabilitation). Results. With the exception of age, there were no significant differences in the demographic and clinical characteristics of the patients in the 2 groups. Shoulder musculoskeletal sonography revealed soft-tissue injury in 7 patients (33%) and 15 patients (71%) in the LBS group at admission and 2 weeks after rehabilitation, respectively (p < 0.05), and in 4 patients (31%) in the HBS group both at admission and 2 weeks after rehabilitation. Conclusions. Acute stroke patients with poor upper limb motor functions are more prone to soft-tissue injury of the shoulder during rehabilitation. © 2009 Wiley Periodicals, Inc. J Clin Ultrasound, 2009.

Background and Aim: We aimed to evaluate the transcriptional characteristics of viral infection-induced woodchuck hepatocellular carcinoma (HCC), to compare the use of human, rat and mouse gene arrays for cross-species hybridization, and to look into gene expression profiles in woodchuck HCC by the combined use of these arrays. Methods: Commercially available human, rat and mouse oligonucleotide microarrays were used to determine the gene expression profiles on the same woodchuck liver samples. Differentially expressed genes between HCC and the surrounding hepatic tissues found in the arrays were selected for quantitative reverse transcription polymerase chain reaction. Results: Despite the difference in the number of the probes from each array, the percentage of genes that were detectable was similar. Stringent microarray data analysis using both supervised and unsupervised methods identified 281 differentially expressed genes via the human array with a false discovery rate (FDR) of 0.99%, 107 genes via the rat array with an FDR of 1.85% and 78 genes via the mouse array with an FDR of 7.41%. Eleven genes were differentially changed in all three arrays that include the upregulation of NPM1, H2AFZ, EEF1G, HNRPAB, RPS18, EIF5, CKS2, ARIH1, RPS12 and RPS10, and the downregulation of EGR1. The quantitative reverse transcription polymerase chain reaction with woodchuck-specific primers confirmed the reliability of the microarray results. Conclusion: This study further demonstrated the utility of cross-species hybridization of microarrays on woodchuck HCC. A combined use of three types of arrays identified more differential genes in HCC than individual arrays with the human array providing the richest information among the three arrays used.

The ZnO and CdSe crystals have similar hexagonal wurtzite structures with a contraction along the c-axis of the crystal, however, different electronic fine structures for ZnO:Fe3+ (D « 0) and CdSe: Fe3+ (D » 0) have been displayed in EPR experiments. This interesting phenomenon has not yet been interpreted at present. In this paper, a reasonable calculation is given by considering the covalent spin-orbit coupling interaction. Our results show that the ground-state splitting in ZnO:Fe3+ is due to the trigonal distortion, whereas the main physical mechanism of the splitting in CdSe:Fe3+ can be attributed to the divergent contributions of |t2〉 and |e〉 sub-orbitals to the spinorbit coupling interaction.

A 102 x 102 matrix for describing the d 5 configuration ions within the tetragonal ligand-field is constituted taking into account the electron electron repulsion, ligand-field, spin orbit coupling, and Zeeman interactions in the weak-field scheme. Two different high-spin-intermediate-spin transitions, which are, respectively, associated with stronger and weaker axial ligand fields of tetragonal sixfold-coordinated iron(III) complexes, are investigated. The diagrams of the energy level positions, magnetic moments, and effective EPR g-factors are derived and expressed as functions of the parameter Δ/ζ, Δ being the energy gap between the high-spin state ( 6 A 1 ) and intermediate-spin states ( 4 A 2 or 4 E) and ζ being the spin orbit coupling coefficient.

Purpose: To investigate the utility of 18F-choline positron emission tomography (PET) scans guidance for SBRT dose painting in patients with prostate cancer and its impact on tumor control probability (TCP) and normal tissue complication probability (NTCP). Methods: Twenty seven patients with localized prostate cancer who had 18F-choline PET/CT scan prior to treatment were included. A pair of nested intraprostatic dominant lesion (IDL) contours (IDLsuv60% and IDLsuv70%) were generated for each patient based on 60% and 70% of maximum prostate uptake on the 18F-choline PET images. GTVreg was delineated on prostate according to the gland boundary seen on CT images. The PTVs (PTVsuv60% and PTVsuv70%) were defined as respective IDLs with a 3-mm margin posteriorly and 5 mm in all other dimensions. Two 5-fraction SBRT plans using VMAT technique along with 10 MV FFF beams, plan36Gy and plan50–55Gy, were generated for each patient. All plans included a dose of 36.25 Gy prescribed to PTVreg. The Plan50–55Gy also included a simultaneous boost dose of 50 Gy and 55 Gy prescribed to the PTVsuv60% and PTVsuv70%, respectively. The utility of 18F-Choline PET-guided SBRT dose escalation was evaluated by its ability to achieve the prescription dose objectives while adhering to organ-at-risk (OAR) dose constraints. The TCP and NTCP calculated by radiological models were also compared between two plans for each patient. Results: In all 54 SBRT plans generated, the planning objectives and dose constraints were met without exception. Plan50–55Gy had a significantly higher dose in PTVsuv60% and PTVsuv70% than those in Plan36Gy (p < 0.05), respectively, while still maintaining a safe OAR sparing profile. In addition, plan50–55Gy had significantly higher TCP than plan36Gy. Conclusion: Using VMAT with FFF beams to incorporate a simultaneous 18F-choline PET-guided radiation boost dose up to 55 Gy into a SBRT plan is technically feasible. This work was supported in part by Congressionally Directed Medical Research Programs Prostate Cancer Research Program grant PC04130, National Institutes of Health/National Cancer Institute grant R41CA110121, and the UNLV Lincy Endowed Assistant Professorship.

Purpose: To investigate the technical feasibility of SBRT dose painting using 18F-NaF positron emission tomography (PET) scans guidance in patients with spine oligometastases from prostate cancer.

Purpose: The GEANT4‐based GATE is a unique and powerful Monte Carlo (MC) platform, which provides a single code library allowing the simulation of several specific applications, e.g. PET, SPECT, CT, internal and external radiotherapy, and hadron therapy. However, its lengthy computing time hinders its routine use in the clinic. Reducing its computing time is therefore of great importance. Thus, a commercial cloud compute service is well suited for GATE MC simulation, both in terms of cost and efficiency. This study achieves a reliable and efficient execution of GATE MC simulation and provides execution frameworks to end‐users. Methods: The GATE software was ported on a commercial compute cloud environment — Amazon Elastic Compute Cloud (EC2). Simulation data was initially loaded onto the master node, and then distributed among independent worker nodes. The filed output from EC2 was sent down to the Amazon Simple Storage Service (S3). The results were finally aggregated on the local computer for display and data analysis. The distributed implementation was executed using a photon beam interacting in a 40 cm by 40 cm by 40 cm water phantom and a four‐head SPECT imaging as benchmarks. Results: A cloud computing environment led to increased calculation speed for the cases implemented in this study. The speed increase scaled approximately linearly with the number of nodes used for computing. The output of the cloud‐based GATE MC simulation was identical to that produced by the single‐threaded implementation, and was resilient to hardware failure, indicating the reliability of the cloud computing platform. The user‐friendliness offered by the workflow implementation does not introduce significant overhead. Conclusion: A cloud computing infrastructure has been established for GATE MC simulation. It substantially improves the speed of simulation, and makes rapid MC simulation for imaging/radiotherapy application possible.

Purpose: The Smart leaf motion calculator (SLMC) in Eclipse treatment planning system is an advanced fluence delivery modeling algorithm as it takes into account fine MLC features including inter-leaf leakage, rounded leaf tips, non-uniform leaf thickness, and the spindle cavity etc. In this study, SLMC and traditional Varian LMC (VLMC) algorithms were investigated, for the first time, in dosimetric characteristics and delivery accuracy of sliding window (SW) IMRT. Methods: The SW IMRT plans of 51 cancer cases were included to evaluate dosimetric characteristics and dose delivery accuracy from leaf motion calculated by SLMC and VLMC, respectively. All plans were delivered using a Varian TrueBeam Linac. The DVH and MUs of the plans were analyzed. Three patient specific QA tools - independent dose calculation software IMSure, Delta4 phantom, and EPID portal dosimetry were also used to measure the delivered dose distribution. Results: Significant differences in the MUs were observed between the two LMCs (p≤0.001).Gamma analysis shows an excellent agreement between the planned dose distribution calculated by both LMC algorithms and delivered dose distribution measured by three QA tools in all plans at 3%/3 mm, leading to a mean pass rate exceeding 97%. The mean fraction of pixels with gamma < 1more » of SLMC is slightly lower than that of VLMC in the IMSure and Delta4 results, but higher in portal dosimetry (the highest spatial resolution), especially in complex cases such as nasopharynx. Conclusion: The study suggests that the two LMCs generates the similar target coverage and sparing patterns of critical structures. However, SLMC is modestly more accurate than VLMC in modeling advanced MLC features, which may lead to a more accurate dose delivery in SW IMRT. Current clinical QA tools might not be specific enough to differentiate the dosimetric discrepancies at the millimeter level calculated by these two LMC algorithms. NIH/NIGMS grant U54 GM104944, Lincy Endowed Assistant Professorship.« less

Purpose: The influence of fringe magnetic fields delivered by magnetic resonance imaging (MRI) on the beam generation and transportation in Linac is still a major challenge for the integration of linear accelerator and MRI (Linac-MRI). In this study, we investigated an optimal magnetic shielding design for Linac-MRI and further characterized the beam trajectory in electron gun. Methods: Both inline and perpendicular configurations were analyzed in this study. The configurations, comprising a Linac-MRI with a 100cm SAD and an open 1.0 T superconductive magnet, were simulated by the 3D finite element method (FEM). The steel shielding around the Linac was included in the 3D model, the thickness of which was varied from 1mm to 20mm, and magnetic field maps were acquired with and without additional shielding. The treatment beam trajectory in electron gun was evaluated using OPERA 3d SCALA with and without shielding cases. Results: When Linac was not shielded, the uniformity of diameter sphere volume (DSV) (30cm) was about 5 parts per million (ppm) and the fringe magnetic fields in electron gun were more than 0.3 T. With shielding, the magnetic fields in electron gun were reduced to less than 0.01 T. For the inline configuration, the radial magnetic fieldsmore » in the Linac were about 0.02T. A cylinder steel shield used (5mm thick) altered the uniformity of DSV to 1000 ppm. For the perpendicular configuration, the Linac transverse magnetic fields were more than 0.3T, which altered the beam trajectory significantly. A 8mm-thick cylinder steel shield surrounding the Linac was used to compensate the output losses of Linac, which shifted the magnetic fields' uniformity of DSV to 400 ppm. Conclusion: For both configurations, the Linac shielding was used to ensure normal operation of the Linac. The effect of magnetic fields on the uniformity of DSV could be modulated by the shimming technique of the MRI magnet. NIH/NIGMS grant U54 GM104944, Lincy Endowed Assistant Professorship.« less

Purpose: The full arcs strategy used in SBRT with RapidArc and unflattened (FFF) beams in large and heterogeneous peripheral non-smallcell lung cancer (NSCLC) appears to be suboptimal as it increases the disadvantageous dose to the contralateral lung, which potentially increases the toxicity to surrounding tissues. In this study, we investigated, for the first time, the dose delivery strategies using partial arcs (PA) and the fully rotational arcs with avoidance sectors (FAAS) for SBRT with FFF beams in peripheral NSCLC patients. Methods: Eighteen patients with NSCLC (stage I and II) were selected for this study. Nine patients with a GTV

Purpose: We investigated the impact of more accurately computed apparent diffusion coefficient (ADC) maps, generated by registration of high-b-value and low-b-value diffusion weighted MR volumes, on early evaluation of tumor response to therapy. Methods: As in previous work, voxel-by-voxel ADC changes in diffusion MR exams during the course of cancer treatment have been shown to be capable of predicting therapeutic response earlier and more accurately than conventional methods. Here we further improved the prediction accuracy using better estimated ADC values. Due to the different susceptibility effects of the different b-field acquisitions, the low- and high-b-value diffusion weighted MR volumes can be markedly out of alignment. Nonlinear registration was employed to align these two volumes and more accurate ADC values were produced. Therapeutic efficacy was then evaluated using the voxel-by-voxel ADC change analysis on the registered pre- and post-treatment ADC maps. Results: We have applied the described method to 14 sets of pre- and post-treatment diffusion MRI volumes of breast cancer patients. The post-treatment exams were acquired in average five weeks after the initiation of treatment. Voxel-by-voxel ADC change analysis with logistic regression (p=0.009) demonstrated that the probability of a responsive treatment is significantly associated with increased ADC values. There were 2 false positives and 1 false negative (sensitivity=80%, specificity=75%). Using more accurate ADC values estimated with nonlinear registration, ADC change analysis yielded 1 false positive and 1 false negative for a sensitivity of 90% and a specificity of 75%. Conclusion: The study suggests registration of high-b-value and low-b-value diffusion weighted MR volumes ensures their voxel correspondence and the subsequent estimation of ADC values are more accurate than ADC computation without registration. The improved ADC maps could increase the accuracy of voxelby- voxel ADC change analysis of registered interval exams in early assessment of treatment response. NIH/NIGMS U54 GM104944, Lincy Endowed Assistant Professorship