bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐E‐I‐22: Dependence On Calibration Phantom and Field Area of the Conversion Factor Used to Calculate Skin Dose During Neuro‐Interventional Fluoroscopic Procedures
Authors: Rana V K , Vijayan S , Rudin S R , Bednarek D R 
Published: July 2014

Purpose:To determine the appropriate calibration factor to use when calculating skin dose with our real‐time dose‐tracking system (DTS) during neuro‐interventional fluoroscopic procedures by evaluating the difference in backscatter from different phantoms and as a function of entrance‐skin field area.Methods:We developed a dose‐tracking system to calculate and graphically display the cumulative skin‐dose distribution in real time. To calibrate the DTS for neuro‐interventional procedures, a phantom is needed that closely approximates the scattering properties of the head. We compared the x‐ray backscatter from eight phantoms: 20‐cm‐thick solid water, 16‐cm diameter water‐filled container, 16‐cm CTDI phantom, modified‐ANSI head phantom, 20‐cm‐thick PMMA, Kyoto‐Kagaku PBU‐ 50 head, Phantom‐Labs SK‐150 head, and RSD RS‐240T head. The phantoms were placed on the patient table with the entrance surface at 15 cm tube‐side from the isocenter of a Toshiba Infinix C‐arm, and the entrance‐skin exposure was measured with a calibrated 6‐cc PTW ionization chamber. The measurement included primary radiation, backscatter from the phantom and forward scatter from the table and pad. The variation in entrance‐skin exposure was also measured as a function of the skin‐entrance area for a 30×30 cm by 20‐cm‐thick PMMA phantom and the SK‐150 head phantom using four different added beam filters.Results:The entranceskin exposure values measured for eight different phantoms differed by up to 12%, while the ratio of entrance exposure of all phantoms relative to solid water showed less than 3% variation with kVp. The change in entrance‐skin exposure with entrance‐skin area was found to differ for the SK‐150 head compared to the 20‐cm PMMA phantom and the variation with field area was dependent on the added beam filtration.Conclusion:To accurately calculate skin dose for neuro‐interventional procedures with the DTS, the phantom for calibration should be carefully chosen since different phantoms can contribute different backscatter for identical exposure parameters.Research supported in part by Toshiba Medical Systems and NIH Grants R43FD0158401, R44FD0158402 and R01EB002873
SU‐E‐I‐23: Design and Clinical Application of External Marking Body in Multi‐ Mode Medical Images Registration and Fusion
Authors: Chen Z , Gong G 
Published: July 2014

Purpose:To design an external marking body (EMB) that could be visible on computed tomography (CT), magnetic resonance (MR), positron emission tomography (PET) and single‐photon emission computed tomography (SPECT) images and to investigate the use of the EMB for multiple medical images registration and fusion in the clinic.Methods:We generated a solution containing paramagnetic metal ions and iodide ions (CT' MR dual‐visible solution) that could be viewed on CT and MR images and multi‐mode image visible solution (MIVS) that could be obtained by mixing radioactive nuclear material. A globular plastic theca (diameter: 3–6 mm) that mothball the MIVS and the EMB was brought by filling MIVS. The EMBs were fixed on the patient surface and CT, MR, PET and SPECT scans were obtained. The feasibility of clinical application and the display and registration error of EMB among different image modalities were investigated.Results:The dual‐visible solution was highly dense on CT images (HU>700). A high signal was also found in all MR scanning (T1, T2, STIR and FLAIR) images, and the signal was higher than subcutaneous fat. EMB with radioactive nuclear material caused a radionuclide concentration area on PET and SPECT images, and the signal of EMB was similar to or higher than tumor signals. The theca with MIVS was clearly visible on all the images without artifact, and the shape was round or oval with a sharp edge. The maximum diameter display error was 0.3 ± 0.2mm on CT and MRI images, and 1.0 ± 0.3mm on PET and SPECT images. In addition, the registration accuracy of the theca center among multi‐mode images was less than 1mm.Conclusion:The application of EMB with MIVS improves the registration and fusion accuracy of multi‐mode medical images. Furthermore, it has the potential to ameliorate disease diagnosis and treatment outcome.
SU‐E‐I‐24: Design and Fabrication of a Multi‐Functional Neck and Thyroid Phantom for Medical Dosimetry and Calibration
Authors: Mehdizadeh S , Sina S , Karimipourfard M , Lotfalizadeh F , Faghihi R , Babaei A 
Published: July 2014

Purpose:The purpose of this study is the design and fabrication of a multipurpose anthropomorphic neck and thyroid phantom for use in medical applications (i.e. quality control of images in nuclear medicine, and dosimetry).Methods:The designed neck phantom is composed of seven elliptic cylindrical slices with semi‐major axis of 14 and semi‐minor axis of 12.5 cm, each having the thickness of 2cm. Thyroid gland, bony part of the neck, and the wind pipe were also built inside the neck phantom.Results:The phantom contains some removable plugs,inside and at its surface to accommodate the TLD chips with different shapes and dimensions, (i.e. rod, cylindrical and cubical TLD chips)for the purpose of medical dosimetry (i.e. in radiology, radiotherapy, and nuclear medicine). For the purpose of quality control of images in nuclear medicine, the removable thyroid gland was built to accommodate the radioactive iodine. The female and male thyroid glands were built in two sizes separately.Conclusion:The designed phantom is a multi‐functional phantom which is applicable for dosimetry in diagnostic radiology, radiotherapy, and quality control of images in nuclear medicine.
SU‐E‐I‐31: Image‐Based Kernel Conversion Technique Normalizes the Reconstruction Kernel Effects in the Measurement of Emphysema Index in CT
Authors: Jin H , Kim J 
Published: July 2014

Purpose:The emphysema index (EI) in CT is a quantitative measure of emphysema, which is known to be affected by reconstruction kernel. This study presents an image‐based kernel conversion technique which converts CT image of sharp kernel to that of standard kernel and evaluates its impact on EI normalization for images obtained with different kernels.Methods:Sixty cases of CT exams obtained with 120kVp, 40mAs, 1mm thickness, of 2 reconstruction kernels (B30f, B50f) were selected from the low dose lung cancer screening database of our institution. An image‐based kernel conversion technique, which converts by applying a conversion function, was performed to the CT data set of B50f to create a converted B30f data set. The conversion function(Fcon) which is the ratio of the spectral components of target and source kernel images, was produced using a training dataset. To test variability due to training dataset, two versions of conversion functions were produced using two different training dataset. The EI (RA950) was measured with a software package (Pulmonalizer, Seoul, South Korea) and compared for data sets of B50f, B30f, and the converted B30f. The accuracy of kernel conversion was evaluated with the mean and standard deviation of pair‐wise differences in EI.Results:Population mean of EI was 28.89±6.48% for B50f data set, 10.96±6.37% for the B30f data set, and 11.27±6.83% for the converted B30f data set. The mean of pair‐wise differences in EI between B30f and the converted B30f is 0.82% for Fcon1 and 1.07% for Fcon2. The correlation between the EI of two data sets was 0.99.Conclusion:Our study demonstrates the feasibility of image‐based kernel conversion technique for normalization of kernel effect in measurement of EI. This technique has a potential to be used in evaluating the longitudinal changes of EI even when the CT was reconstructed with different kernels.The research was supported by the Ministry of Trade, Industry & Energy (10043118)
SU‐E‐I‐34: Intermittent Low‐ and High‐Dose Ethanol Exposure Alters Neurochemical Responses in Adult Rat Brain: An Ex Vivo 1H NMR Spectroscopy at 11.7 T
Authors: Lee Do‐Wan , Kim Sang‐Young , Song Kyu‐Ho , Choe Bo‐Young 
Published: July 2014

Purpose:The first goal of this study was to determine the influence of the dose‐dependent effects of intermittent ethanol intoxication on cerebral neurochemical responses among sham controls and low‐ and high‐dose‐ethanol‐exposed rats with ex vivo high‐resolution spectra. The second goal of this study was to determine the correlations between the metabolite‐metabolite levels (pairs‐of‐metabolite levels) from all of the individual data from the frontal cortex of the intermittent ethanol‐intoxicated rats.Methods:Eight‐week‐old male Wistar rats were divided into 3 groups. Twenty rats in the LDE (n = 10) and the HDE (n = 10) groups received ethanol doses of 1.5 g/kg and 2.5 g/kg, respectively, through oral gavage every 8‐h for 4 days. At the end of the 4‐day intermittent ethanol exposure, one‐dimensional ex vivo 500‐MHz proton nuclear magnetic resonance spectra were acquired from 30 samples of the frontal cortex region (from the 3 groups).Results:Normalized total‐N‐acetylaspartate (tNAA: NAA + NAAG [N‐acetylaspartyl‐glutamate]), gamma‐aminobutyric acid (GABA), and glutathione (GSH) levels were significantly lower in the frontal cortex of the HDE‐exposed rats than that of the LDE‐exposed rats. Moreover, compared to the CNTL group, the LDE rats exhibited significantly higher normalized GABA levels. The 6 pairs of normalized metabolite levels were positively (+) or negatively (−) correlated in the rat frontal cortex as follows: tNAA and GABA (+), tNAA and Aspartate (Asp) (−), myo‐Inositol (mIns) and Asp (−), mIns and Alanine (+), mIns and Taurine (+), and mIns and tNAA (−).Conclusion:Our results suggested that repeated intermittent ethanol intoxication might result in neuronal degeneration and dysfunction, changes in the rate of GABA synthesis, and oxidative stress in the rat frontal cortex. Our ex vivo 1H high‐resolution‐magic angle spinning nuclear magnetic resonance spectroscopy results suggested some novel metabolic markers for the dose‐dependent influence of repeated intermittent ethanol intoxication in the frontal cortex.
SU‐E‐I‐37: Low‐Dose Real‐Time Region‐Of‐Interest X‐Ray Fluoroscopic Imaging with a GPU‐Accelerated Spatially Different Bilateral Filtering
Authors: Chung H , Lee J , Pua R , Jung W , Cho S 
Published: July 2014

Purpose:The purpose of our study is to reduce imaging radiation dose while maintaining image quality of region of interest (ROI) in X‐ray fluoroscopy. A low‐dose real‐time ROI fluoroscopic imaging technique which includes graphics‐processing‐unit‐ (GPU‐) accelerated image processing for brightness compensation and noise filtering was developed in this study.Methods:In our ROI fluoroscopic imaging, a copper filter is placed in front of the X‐ray tube. The filter contains a round aperture to reduce radiation dose to outside of the aperture. To equalize the brightness difference between inner and outer ROI regions, brightness compensation was performed by use of a simple weighting method that applies selectively to the inner ROI, the outer ROI, and the boundary zone. A bilateral filtering was applied to the images to reduce relatively high noise in the outer ROI images. To speed up the calculation of our technique for real‐time application, the GPU‐acceleration was applied to the image processing algorithm. We performed a dosimetric measurement using an ion‐chamber dosimeter to evaluate the amount of radiation dose reduction. The reduction of calculation time compared to a CPU‐only computation was also measured, and the assessment of image quality in terms of image noise and spatial resolution was conducted.Results:More than 80% of dose was reduced by use of the ROI filter. The reduction rate depended on the thickness of the filter and the size of ROI aperture. The image noise outside the ROI was remarkably reduced by the bilateral filtering technique. The computation time for processing each frame image was reduced from 3.43 seconds with single CPU to 9.85 milliseconds with GPU‐acceleration.Conclusion:The proposed technique for X‐ray fluoroscopy can substantially reduce imaging radiation dose to the patient while maintaining image quality particularly in the ROI region in real‐time.
SU‐E‐I‐39: Molecular Image Guided Cancer Stem Cells Therapy
Authors: Abdollahi H 
Published: July 2014

Purpose:Cancer stem cells resistance to radiation is a problematic issue that has caused a big fail in cancer treatment.Methods:As a primary work, molecular imaging can indicate the main mechanisms of radiation resistance of cancer stem cells. By developing and commissioning new probes and nanomolecules and biomarkers, radiation scientist will able to identify the essential pathways of radiation resistance of cancer stem cells. As the second solution, molecular imaging is a best way to find biological target volume and delineate cancer stem cell tissues. In the other hand, by molecular imaging techniques one can image the treatment response in tumor and also in normal tissue. In this issue, the response of cancer stem cells to radiation during therapy course can be imaged, also the main mechanisms of radiation resistance and finding the best radiation modifiers (sensitizers) can be achieved by molecular imaging modalities. In adaptive radiotherapy the molecular imaging plays a vital role to have higher tumor control probability by delivering high radiation doses to cancer stem cells in any time of treatment. The outcome of a feasible treatment is dependent to high cancer stem cells response to radiation and removing all of which, so a good imaging modality can show this issue and preventing of tumor recurrence and metastasis.Results:Our results are dependent to use of molecular imaging as a new modality in the clinic. We propose molecular imaging as a new radiobiological technique to solve radiation therapy problems due to cancer stem cells.Conclusion:Molecular imaging guided cancer stem cell diagnosis and therapy is a new approach in the field of cancer treatment. This new radiobiological imaging technique should be developed in all clinics as a feasible tool that is more biological than physical imaging.
SU‐E‐I‐41: Non‐Cartesian MR Image Reconstruction with Integrated Gradient Non‐Linearity Correction
Authors: Tao S , Trzasko JD , Polley TW , Shu Y , Bernstein MA 
Published: July 2014

Purpose:Nonlinearities in the spatial encoding gradients of MRI systems cause geometric distortion in images. Typically, this is retrospectively corrected via image‐domain interpolation (a.k.a., “gradwarp”) albeit with a loss of spatial resolution. For non‐Cartesian MRI, the latter problem is exaggerated by noise and undersampling artifact. In this study, we describe a novel correction strategy that accounts for gradient nonlinearities during — rather than after — non‐Cartesian MRI reconstruction, and demonstrate that this approach mitigates the resolution loss that can occur with standard methods.Methods:To test the proposed method, the American College of Radiology (ACR) quality control phantom was scanned on at 1.5 T (General Electric, v16.0, “zoom” gradient) using a 1.6x undersampled 3D non‐ Cartesian Shells trajectory (GRE, FOV=24 cm3, 120 shells, 16552 shots, 512 readout, matrix=2403). Image reconstruction was first performed via standard k‐space density‐compensated gridding and retrospectively corrected via cubic spline interpolation. Image reconstruction was then separately performed using a k‐space and image‐domain densitycompensated type‐3 non‐uniform fast Fourier transform (NUFFT), which provides a direct mapping between non‐Cartesian k‐space samples and warped image space voxel locations. Thus, no separate distortion correction procedure is needed for the proposed approach. The gradient distortion field was determined using vendor provided calibration data.Results:Phantom scan results show that both processing approaches successfully correct geometric distortion. However, visual inspection of the ACR phantom spatial resolution inserts shows that the proposed strategy preserves the resolution of the nominal (uncorrected) reconstruction while “gradwarp” imparts marked spatial blurring (especially for the 1.0 and 1.1 mm inserts) and thus resolution loss.Conclusion:We' ve presented a novel reconstruction strategy for non‐Cartesian MRI that corrects for gradient nonlinearities during — rather than after — reconstruction, and thus better preserves image resolution than traditional interpolation‐based methods. This approach is expected to be especially advantageous when imaging with non‐standard magnet geometries.NIH RR018898; NIH EB10065
SU‐E‐I‐43: Pediatric CT Dose and Image Quality Optimization
Authors: Stevens G , Singh R 
Published: July 2014

Purpose:To design an approach to optimize radiation dose and image quality for pediatric CT imaging, and to evaluate expected performance.Methods:A methodology was designed to quantify relative image quality as a function of CT image acquisition parameters. Image contrast and image noise were used to indicate expected conspicuity of objects, and a wide‐cone system was used to minimize scan time for motion avoidance. A decision framework was designed to select acquisition parameters as a weighted combination of image quality and dose. Phantom tests were used to acquire images at multiple techniques to demonstrate expected contrast, noise and dose. Anthropomorphic phantoms with contrast inserts were imaged on a 160mm CT system with tube voltage capabilities as low as 70kVp. Previously acquired clinical images were used in conjunction with simulation tools to emulate images at different tube voltages and currents to assess human observer preferences.Results:Examination of image contrast, noise, dose and tube/generator capabilities indicates a clinical task and object‐size dependent optimization. Phantom experiments confirm that system modeling can be used to achieve the desired image quality and noise performance. Observer studies indicate that clinical utilization of this optimization requires a modified approach to achieve the desired performance.Conclusion:This work indicates the potential to optimize radiation dose and image quality for pediatric CT imaging. In addition, the methodology can be used in an automated parameter selection feature that can suggest techniques given a limited number of user inputs.G Stevens and R Singh are employees of GE Healthcare.
SU‐E‐I‐47: Simultaneous Acquisition Quality Assurance and Design of Fused MRIMRS Phantom for the Performance Evaluation
Authors: Song Kyu‐Ho , Lee Do‐Wan , Kim Sang‐Young , Choe Bo‐Young 
Published: July 2014

Purpose:The objectives of this study were to develop MRI‐MRS fused phantom with metabolite inserts for QA, to optimize simultaneously QA parameters using fused phantom and to conduct quantitative analysis of sixteen metabolites solution with layered shape vials using localization sequence.Methods:The circular cylinder body was filled with waterdiluted CuSO4(0.7g/L) for having a T1 time shorting function and NaCl(75mM) to make similarly with bodily salt. The solutions of the 10 metabolites were prepared at about 100mM and pH of the solution was adjusted using K2HPO4(72mM) and KH2PO4(28mM) in H2O at pH 7.0. All measurements of MRI, MRS were made using a 3.0 T scanner (Achiva Tx 3.0 T) with SENSE – 32 channel head coil. The water signal of each volume of interest (VOI) was suppressed by variable pulse powers and optimized relaxation delays (VAPOR) applied before progress of the scan. The MRS scan parameters were as follows: point‐resolved spectroscopy (PRESS) sequence; TR, 2000 ms; TE, 35 ms; shim, iterative VOI; NSA, 64. In addition, this study was conducted with jMRUI‐5.0 software, with AMARES for spectral fitting.Results:Results of measured magnetic resonance imaging (MRI) factors were as follows: geometric accuracy (191.23±0.60), low contrast object detectability (28.13±0.835), image‐shift distortion (0.41±0.0032). Results of measured magnetic resonance spectroscopy (MRS) factors were as follows: signal‐to‐noise ratio (SNR) of the NAA (25.95±0.35), water suppression percent (99.70±0.09 %), line width of water peak (5.75±0.91 Hz).Conclusion:This study was to perform QA on SVS technique using the ACR‐MRS phantom which was refered ACR test guideline. The present study is being measured the quantitative accuracy of the metabolite and the accuracy of the position of the VOI which could be performed by layered shape vials. When QA protocol factors is established in this experiment, it is possible as MVS QA guideline.
SU‐E‐I‐50: Ultrahigh Resolution Reduced Field‐Of‐View Diffusion Tensor Imaging in the Spinal Cord
Authors: Gaggl W , Reuss J , Field A 
Published: July 2014

Purpose:Diffusion Tensor Imaging (DTI) is a well‐established MRI imaging modality for applications in the brain. The typically attainable imaging resolution for clinical DTI sequences is insufficient to image small lesions and assess injury with microstructural changes in the spinal cord (SC). Attempts to reduce the field‐of‐view (FOV) for increasing the imaging resolution have been made using rectangular FOV geometries that work well to efficiently image the sagittal plane. The highest structural details in the SC are however in the axial plane, most efficiently covered by a circular FOV. The aim of this study was to increase the axial DTI resolution in the SC to distinguish the dorsal spinal white‐matter bundles within clinically acceptable acquisition times.Methods:A multishot reduced FOV DTI technique named eZOOM that utilizes spatially selective radio‐frequency (RF) pulses and spiral readout has recently been developed by the author (Gaggl, MRM 2014) for application in the brain. In this study the method was adapted to the unique geometry of multichannel spinal RF coil arrays, with improved correction of blurring and misregistration and including peripheral gating to minimize cerebrospinal fluid flow‐artifacts. Several diffusion metrics including the novel normalized axial diffusivity DAn=λ1/∑λ (Gaggl, ASFNR 2013) were calculated and compared to current methods.Results:Sub‐millimeter square‐voxel imaging resolutions with image voxel volumes of approximately 1mm3 for a circular axial 8‐cm FOV and 15 diffusion weighting gradient directions were achieved in human for multislice image stacks in the SC with total imaging times of less than 30 minutes at 3T, enabling the separation of important spinal fiber tracts.Conclusion:The presented technique improves imaging resolution for DTI in the spinal cord compared to current clinical sequences while allowing to prescribe imaging geometries that excite only a small axial circular FOV in and around the spinal cord and reducing blurring and artifacts.