bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐E‐I‐03: Lateral Truncation Artifact Correction for 4DCBCT‐Based Motion Modeling and Dose Assessment
Authors: Dhou S , Cifter F , Myronakis M , Berbeco R , Lewis J , Cai W 
Published: June 2015

Purpose:To allow accurate motion modeling and dose assessment based on 4DCBCT by addressing the limited field of view (FOV) and lateral truncation artifacts in current clinical CBCT systems. Due to the size and geometry of onboard flat panel detects, CBCT often cannot cover the entire thorax of adult patients. We implement method to extend the images generated from 4DCBCT‐based motion models and correct lateral truncation artifacts.Methods:The method is based on deforming a reference 4DCT image containing the entire patient anatomy to the (smaller) CBCT image within the higher quality CBCT FOV. Next, the displacement vector field (DVF) derived inside the CBCT FOV is smoothly extrapolated out to the edges of the body. These extrapolated displacement vectors are used to generate a new body contour and HU values outside of the CBCT FOV. This method is applied to time‐varying volumetric images (3D fluoroscopic images) generated from a 4DCBCT‐based motion model at 2 Hz. Six XCAT phantoms are used to test this approach and reconstruction accuracy is investigated.Results:The normalized root mean square error between the corrected images generated from the 4DCBCT‐based motion model and the ground truth XCAT phantom at each time point is generally less than 20%. These results are comparable to results from 4DCT‐based motion models. The anatomical structures outside the CBCT FOV can be reconstructed with an error comparable to that inside the FOV. The resulting noise is comparable to that of 4DCT.Conclusions:The proposed approach can effectively correct the artifact due to lateral truncation in 4DCBCT‐based motion models. The quality of the resulting images is comparable to images generated from 4DCT‐based motion models. Capturing the body contour and anatomy outside the CBCT FOV makes more reasonable dose calculations possible.
SU‐E‐I‐07: Response Characteristics and Signal Conversion Modeling of KV Flat‐Panel Detector in Cone Beam CT System
Authors: Wang Yu , Cao Ruifen , Pei Xi , Wang Hui , Hu Liqin ,   FDS Team
Published: June 2015

Purpose:The flat‐panel detector response characteristics are investigated to optimize the scanning parameter considering the image quality and less radiation dose. The signal conversion model is also established to predict the tumor shape and physical thickness changes.Methods:With the ELEKTA XVI system, the planar images of 10cm water phantom were obtained under different image acquisition conditions, including tube voltage, electric current, exposure time and frames. The averaged responses of square area in center were analyzed using Origin8.0. The response characteristics for each scanning parameter were depicted by different fitting types. The transmission measured for 10cm water was compared to Monte Carlo simulation. Using the quadratic calibration method, a series of variable‐thickness water phantoms images were acquired to derive the signal conversion model. A 20cm wedge water phantom with 2cm step thickness was used to verify the model. At last, the stability and reproducibility of the model were explored during a four week period.Results:The gray values of image center all decreased with the increase of different image acquisition parameter presets. The fitting types adopted were linear fitting, quadratic polynomial fitting, Gauss fitting and logarithmic fitting with the fitting R‐Square 0.992, 0.995, 0.997 and 0.996 respectively. For 10cm water phantom, the transmission measured showed better uniformity than Monte Carlo simulation. The wedge phantom experiment show that the radiological thickness changes prediction error was in the range of (‐4mm, 5mm). The signal conversion model remained consistent over a period of four weeks.Conclusion:The flat‐panel response decrease with the increase of different scanning parameters. The preferred scanning parameter combination was 100kV, 10mA, 10ms, 15frames. It is suggested that the signal conversion model could effectively be used for tumor shape change and radiological thickness prediction.Supported by National Natural Science Foundation of China (81101132, 11305203) and Natural Science Foundation of Anhui Province (11040606Q55, 1308085QH138)
SU‐E‐I‐11: A New Cone‐Beam CT System for Bedside Head Imaging
Authors: Sun H , Zeng W , Xu P , Wang Z , Xing X , Sun M 
Published: June 2015

Purpose:To design and develop a new mobile cone‐beam CT (CBCT) system for head imaging with good soft‐tissue visibility, to be used bedside in ICU and neurosurgery department to monitor treatment and operation outcome in brain patients.Methods:The imaging chain consists of a 30cmx25cm amorphous silicon flat panel detector and a pulsed, stationary anode monoblock x‐ray source of 100kVp at a maximal tube current of 10mA. The detector and source are supported on motorized mechanisms to provide detector lateral shift and source angular tilt, enabling a centered digital radiographic imaging mode and half‐fan CBCT, while maximizing the use of the x‐ray field and keep the source to detector distance short. A focused linear anti‐scatter grid is mounted on the detector, and commercial software with scatter and other corrective algorithms is used for data processing and image reconstruction. The gantry rotates around a horizontal axis, and is able to adjust its height for different patient table positions. Cables are routed through a custom protective sleeve over a large bore with an in‐plane twister band, facilitating single 360‐degree rotation without a slip‐ring at a speed up to 5 seconds per rotation. A UPS provides about 10 minutes of operation off the battery when unplugged. The gantry is on locked casters, whose brake is control by two push handles on both sides for easy reposition. The entire system is designed to have a light weight and a compact size for excellent maneuverability.Results:System design is complete and main imaging components are tested. Initial results will be presented and discussed later in the presentation.Conclusion:A new mobile CBCT system for head imaging is being developed. With its compact size, a large bore, and quality design, it is expected to be a useful imaging tool for bedside uses.The work is supported by a grant from Chinese Academy of Sciences.
SU‐E‐I‐15: Quantitative Evaluation of Dose Distributions From Axial, Helical and Cone‐Beam CT Imaging by Measurement Using a Two‐Dimensional Diode‐Array Detector
Authors: Chacko M , Aldoohan S , Sonnad J , Ahmad S , Ali I 
Published: June 2015

Purpose:To evaluate quantitatively dose distributions from helical, axial and cone‐beam CT clinical imaging techniques by measurement using a two‐dimensional (2D) diode‐array detector.Methods:2D‐dose distributions from selected clinical protocols used for axial, helical and cone‐beam CT imaging were measured using a diode‐array detector (MapCheck2). The MapCheck2 is composed from solid state diode detectors that are arranged in horizontal and vertical lines with a spacing of 10 mm. A GE‐Light‐Speed CT‐simulator was used to acquire axial and helical CT images and a kV on‐board‐imager integrated with a Varian TrueBeam‐STx machine was used to acquire cone‐beam CT (CBCT) images.Results:The dose distributions from axial, helical and cone‐beam CT were non‐uniform over the region‐of‐interest with strong spatial and angular dependence. In axial CT, a large dose gradient was measured that decreased from lateral sides to the middle of the phantom due to large superficial dose at the side of the phantom in comparison with larger beam attenuation at the center. The dose decreased at the superior and inferior regions in comparison to the center of the phantom in axial CT. An asymmetry was found between the right‐left or superior‐inferior sides of the phantom which possibly to angular dependence in the dose distributions. The dose level and distribution varied from one imaging technique into another. For the pelvis technique, axial CT deposited a mean dose of 3.67 cGy, helical CT deposited a mean dose of 1.59 cGy, and CBCT deposited a mean dose of 1.62 cGy.Conclusions:MapCheck2 provides a robust tool to measure directly 2D‐dose distributions for CT imaging with high spatial resolution detectors in comparison with ionization chamber that provides a single point measurement or an average dose to the phantom. The dose distributions measured with MapCheck2 consider medium heterogeneity and can represent specific patient dose.
SU‐E‐I‐18: Evaluation of a Lung Density CT Standard Reference Material
Authors: Chen‐Mayer H , Avila R , John L , Levine Z , Yankelevitz D 
Published: June 2015

Purpose:To evaluate quantitative lung density CT using a Standard Reference Material (SRM) with SI traceable physical densities in a clinical setting free from physiological noise.Methods:The 5‐density (0.06 to 0.23 g/cc) suite of polyurethane foams developed as a CT lung density reference (SRM‐2088) was measured inside an anthropomorphic chest phantom in a 64‐row scanner, to assess the mean HU value and its distribution. Two tube current settings (200 mA and 50 mA) were used to represent high‐ and low‐dose CT clinically, with back‐to‐back repeat scans, and for each scan the image reconstruction was performed at slice thicknesses of 0.625 mm and 1.25 mm. A volume histogram was generated for the entire suite, and was fitted to a function with 5 Gaussian peaks, each reporting a centroid (mean HU) and standard deviation (SD in HU) as a measure of the accuracy and precision of the measurement. Statistical analysis was performed using the two levels of mA and recon slice thickness as factors to study the effect on the centroid and the SD.Results:Neither dose nor thickness has significant effect on the centroid, but both have significant effect on the SD. At 200 mA, the observed average SD is about half of that at 50 mA. With the thickness doubled, the SD decreased by a factor of 1.17, providing a parameter relating spatial resolution and noise. The SD is more than 3 times higher when compared to the SRM in‐air measurement (without the attenuation and scattering from the chest wall) performed earlier, whereas for the centroid excellent agreement was observed.Conclusion:The study provides the underlying uncertainty assessment for these standard references in the lung density range in a set of scanning conditions, forming the basis for estimating the sensitivity to changes in lung density in a clinical setting.Dr. David Yankelevitz receives royalty payments from General Electric Company.
SU‐E‐I‐84: Accuracy Comparison of Multi‐Modality Image‐Based Volumes of Rodent Solid Tumors Using In‐Air Micro‐CT Image Volume
Authors: Lee Y , Fullerton G , Goins B 
Published: June 2015

Purpose:Tumor volume is considered as a better predictor for therapy response monitoring and tumor staging over Response Evaluation Criteria In Solid Tumors (RECIST) or World Health Organization (WHO) criteria. In this study, the accuracy of subcutaneous rodent tumor volumes using preclinical magnetic resonance imaging (MRI), micro‐computed tomography (micro‐CT) and ultrasound (US) equipment and with an external caliper was compared using in‐air micro‐CT image volume of excised tumors determined as reference tumor volume in our prior study.Methods:MR, US and micro‐CT images of subcutaneous SCC4 head and neck tumor xenografts were acquired 4, 6, 9, 11 and 13 days after tumor cell inoculation. Before MR and US scans, caliper measurements were made. After tumors were excised, in‐air micro‐CT imaging and ex vivo caliper measurements were performed. Tumor volumes were calculated using formula V = (π/6)*a*b*c where a, b and c are the maximum diameters in three perpendicular dimensions determined by the three image modalities and caliper, and compared with reference tumor volume by linear regression analysis as well as Bland‐Altman plots. A one‐way Analysis of Variance (ANOVA) test was also performed to compare volumes among caliper measurements.Results:The correlation coefficients (R2) of the regression lines for tumor volumes measured by the three imaging modalities and caliper were 0.9939, 0.9669, 0.9806, 0.9274, 0.9619 and 0.9819 for MRI, US and micro‐CT, caliperbeforeMRI, caliperbeforeUS and ex vivo caliper respectively. In Bland‐Altman plots, the average of tumor volume difference from reference tumor volume (bias) was significant for caliper and micro‐ CT, but not for MRI and US. Comparison of caliper measurements showed a significant difference (p < 0.05).Conclusion:Using the in‐air micro‐CT image volume, tumor volume measured by MRI was the most accurate among the three imaging modalities. In vivo caliper volume measurements showed unreliability while ex vivo caliper measurements reduced errors.
SU‐E‐I‐89: The Role of Reflectance Confocal Microscopy in the Screening of Hypo‐Pigmented Mycosis Fungoides
Authors: Gao M , Liu H , Fan T 
Published: June 2015

Purpose:Hypopigmented mycosis fungoides (HMF) is a rare variant of cutaneous T‐cell lymphoma(CTCL), and the diagnosis of HMF is often missed due to its low incidence and lack of clinical suspicion. Thus, the misdiagnosis and failure to obtain biopsies lead to a long latency period from onset of hypopigmented patches to diagnosis and treatment. In this study,we aimed to establish a new evaluation system of psoriasis by imaging the ultrastructures of the lesions with reflectance confocal microscopy(RCM).Methods:We used the RCM to screen the hypopigmented lesions, and those lesions were biopsied and analyzed if there was some specific findings in the RCM images. In 2014,we performed RCM imaging of 150 cases with hypopigmented lesions and 15 cases of which were confirmed with histological analysis.Results:Based on the RCM findings,there was no significant melanin and melanocytes changes in the hypopigmented — to‐achromic lesions, or sometimes even with a vitiligo‐like aspect, compared with the peri‐lesional normal skin, and mononuclear inflammatory cells in the epidermis and upper dermis is the most valuable clue for the suspicious of MF. Then the histology analysis confirmed the diagnosis of HMF. Those 15 cases suspicious of MF under RCM image were all diagnosed as MF by histological analysis.Conclusions:The RCM findings correlated well with the histology results in the screening of HMF, which provides an important tool in the evaluation of HMF.
SU‐E‐I‐90: Characterizing Small Animal Lung Properties Using Speckle Observed with An In‐Line X‐Ray Phase Contrast Benchtop System
Authors: Garson A , Gunsten S , Guan H , Vasireddi S , Brody S , Anastasio M 
Published: June 2015

Purpose:We demonstrate a novel X‐ray phase‐contrast (XPC) method for lung imaging representing a paradigm shift in the way small animal functional imaging is performed. In our method, information regarding airway microstructure that is encoded within speckle texture of a single XPC radiograph is decoded to produce 2D parametric images that will spatially resolve changes in lung properties such as microstructure sizes and air volumes. Such information cannot be derived from conventional lung radiography or any other 2D imaging modality. By computing these images at different points within a breathing cycle, dynamic functional imaging will be readily achieved without the need for tomography. Methods: XPC mouse lung radiographs acquired in situ with an in‐line X‐ray phase contrast benchtop system. The lung air volume is varied and controlled with a small animal ventilator. XPC radiographs will be acquired for various lung air volume levels representing different phases of the respiratory cycle. Similar data will be acquired of microsphere‐based lung phantoms containing hollow glass spheres with known distributions of diameters. Image texture analysis is applied to the data to investigate relationships between texture characteristics and airspace/microsphere physical properties.Results:Correlations between Fourier‐based texture descriptors (FBTDs) and regional lung air volume indicate that the texture features in 2D radiographs reveal information on 3D properties of the lungs. For example, we find for a 350 × 350 πm2 lung ROI a linear relationship between injected air volume and FBTD value with slope and intercept of 8.9×105 and 7.5, respectively.Conclusion:We demonstrate specific image texture measures related to lung speckle features are correlated with physical characteristics of refracting elements (i.e. lung air spaces). Furthermore, we present results indicating the feasibility of implementing the technique with a simple imaging system design, short exposures, and low dose which provides potential for widespread use in laboratory settings for in vivo studies.This research was supported in part by NSF Award CBET1263988.
SU‐E‐J‐06: Additional Imaging Guidance Dose to Patient Organs Resulting From X‐Ray Tubes Used in CyberKnife Image Guidance System
Authors: Sullivan A , Ding G 
Published: June 2015

Purpose:The use of image‐guided radiation therapy (IGRT) has become increasingly common, but the additional radiation exposure resulting from repeated image guidance procedures raises concerns. Although there are many studies reporting imaging dose from different image guidance devices, imaging dose for the CyberKnife Robotic Radiosurgery System is not available. This study provides estimated organ doses resulting from image guidance procedures on the CyberKnife system.Methods:Commercially available Monte Carlo software, PCXMC, was used to calculate average organ doses resulting from x‐ray tubes used in the CyberKnife system. There are seven imaging protocols with kVp ranging from 60 – 120 kV and 15 mAs for treatment sites in the Cranium, Head and Neck, Thorax, and Abdomen. The output of each image protocol was measured at treatment isocenter. For each site and protocol, Adult body sizes ranging from anorexic to extremely obese were simulated since organ dose depends on patient size. Doses for all organs within the imaging field‐of‐view of each site were calculated for a single image acquisition from both of the orthogonal x‐ray tubes.Results:Average organ doses were <1.0 mGy for every treatment site and imaging protocol. For a given organ, dose increases as kV increases or body size decreases. Higher doses are typically reported for skeletal components, such as the skull, ribs, or clavicles, than for softtissue organs. Typical organ doses due to a single exposure are estimated as 0.23 mGy to the brain, 0.29 mGy to the heart, 0.08 mGy to the kidneys, etc., depending on the imaging protocol and site.Conclusion:The organ doses vary with treatment site, imaging protocol and patient size. Although the organ dose from a single image acquisition resulting from two orthogonal beams is generally insignificant, the sum of repeated image acquisitions (>100) could reach 10–20 cGy for a typical treatment fraction.
SU‐E‐J‐08: Comparison of Unintended Radiation Doses to Organs at Risk Resulting From the Out‐Of‐Field Therapeutic Beams and From Image‐Guidance X‐Ray Procedures
Authors: Ding G , Wang L 
Published: June 2015

Purpose:The unintended radiation dose to organs at risk (OAR) can be contributed from imaging guidance procedures as well as from leakage and scatter of therapeutic beams. This study compares the imaging dose with the unintended out‐of‐field therapeutic dose to patient sensitive organs.Methods:The Monte Carlo EGSnrc user codes, BEAMnrc and DOSXYZnrc, were used to simulate kV X‐ray sources from imaging devices as well as the therapeutic IMRT/VMAT beams and to calculate doses to target and OARs on patient treatment planning CT images. The accuracy of the Monte Carlo simulations was benchmarked against measurements in phantoms. The dose‐volume histogram was utilized in analyzing the patient organ doses.Results:The dose resulting from Standard Head kV‐CBCT scans to bone and soft tissues ranges from 0.7 to 1.1 cGy and from 0.03 to 0.3 cGy, respectively. The dose resulting from Thorax scans on the chest to bone and soft tissues ranges from 1.1 to 1.8 cGy and from 0.3 to 0.6 cGy, respectively. The dose resulting from Pelvis scans on the abdomen to bone and soft tissues range from 3.2 to 4.2 cGy and from 1.2 to 2.2 cGy, respectively. The out‐of‐field doses to OAR are sensitive to the distance between the treated target and the OAR. For a typical Head‐and‐Neck IMRT/VMAT treatment the out‐of‐field doses to eyes are 1–3% of the target dose, or 2–6 cGy per fraction.Conclusion:The imaging doses to OAR are predictable based on the imaging protocols used when OARs are within the imaged volume and can be estimated and accounted for by using tabulated values. The unintended out‐of‐field doses are proportional to the target dose, strongly depend on the distance between the treated target and OAR, and are generally higher comparing to the imaging dose.This work was partially supported by Varian research grant VUMC40590.
SU‐E‐J‐15: Automatically Detect Patient Treatment Position and Orientation in KV Portal Images
Authors: Qiu J , Yang D 
Published: June 2015

Purpose:In the course of radiation therapy, the complex information processing workflow will Result in potential errors, such as incorrect or inaccurate patient setups. With automatic image check and patient identification, such errors could be effectively reduced. For this purpose, we developed a simple and rapid image processing method, to automatically detect the patient position and orientation in 2D portal images, so to allow automatic check of positions and orientations for patient daily RT treatments.Methods:Based on the principle of portal image formation, a set of whole body DRR images were reconstructed from multiple whole body CT volume datasets, and fused together to be used as the matching template. To identify the patient setup position and orientation shown in a 2D portal image, the 2D portal image was preprocessed (contrast enhancement, down‐sampling and couch table detection), then matched to the template image so to identify the laterality (left or right), position, orientation and treatment site.Results:Five day's clinical qualified portal images were gathered randomly, then were processed by the automatic detection and matching method without any additional information. The detection results were visually checked by physicists. 182 images were correct detection in a total of 200kV portal images. The correct rate was 91%.Conclusion:The proposed method can detect patient setup and orientation quickly and automatically. It only requires the image intensity information in KV portal images. This method can be useful in the framework of Electronic Chart Check (ECCK) to reduce the potential errors in workflow of radiation therapy and so to improve patient safety. In addition, the auto‐detection results, as the patient treatment site position and patient orientation, could be useful to guide the sequential image processing procedures, e.g. verification of patient daily setup accuracy.This work was partially supported by research grant from Varian Medical System.