bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐E‐P‐50: Automated Uniformity Measurements Using a Comprehensive Tomosynthesis QA Phantom
Authors: Olafsdottir H , Goodenough D , Oskarsdottir G , Olafsson I , Fredriksson J , Mallozzi R , Healy A , Kristbjornsson A , Kristinsson S , Levy J 
Published: June 2015

Purpose:The purpose of this study is to look at an automated approach to measure uniformity in DBT using a comprehensive QA phantom versus using a separate uniformity phantom. Our question is whether the uniformity can be reasonably measured within the backdrop of the other test objects?Methods:Using the Tomophan ™ from The Phantom Laboratory, both the regional uniformity and the global uniformity was studied. The uniform ROIs are selected carefully to minimize the effect from other test targets.To measure the regional uniformity two large (10mm radius) regions of interest (ROI) are placed in an anterior and lateral position within the phantom image. The locations of the ROIs are shown in figures 1 and 2. Both the mean value and standard deviation of the pixel value within those regions is computed and observed in the slice (z) direction. The results of the global uniformity test indicate how well the imaging system performs in preserving the uniformity within a given slice. The global uniformity looks at the mean value and standard deviation of the pixel value within five ROIs all with a radius of 5 mm placed at various locations within the phantom. The five smaller ROIs indicate how well the imaging device performs in preserving the uniformity within the slice. Because tomosynthesis systems do not use a set pixel value scale, such as the Hounsfield scale in CT, the percentage of the maximum absolute difference between uniformity regions was used for vendor comparison.Results:Comparison of 49 cases from six different vendors showed that the uniformity measurements can differ somewhat between scans for the same vendor and between vendors.Conclusion:By carefully selecting regions of interest, valuable information can be gained offering information on tomosynthesis image uniformity by using phantom that also contains other targets.Research supported by Image Owl, Inc., The Phantom Laboratory, Inc. and Raforninn ehf.; Authors Mallozzi and Healy employed by The Phantom Laboratory, Inc.; Author Goodenough is a consultant to The Phantom Laboratory, Inc.; Authors Fredriksson, Kristbjornsson, Olafsson, Oskarsdottir, and Olafsdottir are employeed by Raforninn ehf.
SU‐E‐P‐51: Dosimetric Comparison to Organs at Risk Sparing Using Volumetric‐Modulated Arc Therapy Versus Intensity‐Modulated Radiotherapy in Postoperative Radiotherapy of Left‐Sided Breast Cancer
Authors: Qiao L , Xie J , Cheng J , Liang N , Deng G , Zhang J , Zhang J , Luo H 
Published: June 2015

Purpose:To compare the dosimetric characteristics of volumetric‐modulated arc therapy (VMAT) and intensity‐modulated radiotherapy (IMRT) techniques in treatment planning for left‐sided breast cancer patients with modified radical mastectomy.Methods:Twenty‐four left‐sided breast cancer patients treated with modified radical mastectomy were selected in this study. The planning target volume (PTV) was generated by using 7‐mm uniform expansion of the clinical target volume (CTV) in all direction except the skin surface. The organs at risk (OARs) included heart, left lung, right lung, and right breast. Dose volume histograms (DVHs) were utilized to evaluate the dose distribution in PTV and OARs.Results:Both VMAT and IMRT plans met the requirement of PTV coverage. VMAT was superior to IMRT in terms of conformity, with a statistically significant difference (p=0.024). Mean doses, V5 and V10 of heart and both lungs in VMAT plans were significantly decreased compared to IMRT plans (P<0.05), but in terms of heart volume irradiated by high doses (V30 and V45), no significant differences were observed (P>0.05). For right breast, VMAT showed the reduction of V5 in comparison with IMRT (P<0.05). Additionally, the mean number of monitor units (MU) and treatment time in VMAT (357.21, 3.62 min) were significantly less than those in IMRT (1132.85, 8.74 min).Conclusion:VMAT showed similar PTV coverage and significant advantage in OARs sparing compared with IMRT, especially in terms of decreased volumes irradiated by low doses, while significantly reducing the treatment time and MU number.
SU‐E‐P‐57: Radiation Doses Assessment to Paediatric Patients for Some Digital Diagnostic Radiology Examination in Emergency Department in Qatar
Authors: Abdallah I , Aly A , Al Naemi H 
Published: June 2015

Purpose:The aim of this study was to evaluate radiation doses to pediatric patients undergoing standard radiographic examinations using Direct Digital Radiography (DDR) in Paediatric emergency center of Hamad General Hospital (HGH) in state of Qatar and compared with regional and international Dose Reference Levels (DRLs).Methods:Entrance Skin Dose (ESD) was measured for 2739 patients for two common X‐ray examinations namely: Chest AP/PA, Abdomen. Exposure factors such as kV, mAs and Focal to Skin Distance (FSD) were recorded for each patient. Tube Output was measured for a range of selected kV values. ESD for each individual patient was calculated using the tube output and the technical exposure factors for each examination. The ESD values were compared with the some international Dose Reference Levels (DRL) for all types of examinations.Results:The most performed procedure during the time of this study was chest PA/PA (85%). The mean ESD values obtained from AP chest, PA chest and AP abdomen ranged 91–120, 80–84 and 209 – 659 µGy per radiograph for different age's groups respectively. Two protocols have been used for chest AP and PA using different radiological parameters, and the different of ESD values for chest PA and were 41% for 1 years old child, 57% for 5 years old for chest AP.Conclusion:The mean ESD were compared with those found in literature and were found to be comparable. The radiation dose can be reduced more for Chest AP and PA examination by optimization of each investigation and hence more studies are required for this task. The results presented will serve as a baseline data needed for deriving local reference doses for pediatric X‐ray examinations in this local department and hence it can be applied in the whole Qatar.
SU‐E‐P‐58: Dosimetric Study of Conventional Intensity‐Modulated Radiotherapy and Knowledge‐Based Radiation Therapy for Postoperation of Cervix Cancer
Authors: Ma C , Yin Y 
Published: June 2015

Purpose:To compare the dosimetric difference of the target volume and organs at risk(OARs) between conventional intensity‐modulated radiotherapy(C‐IMRT) and knowledge‐based radiation therapy (KBRT) plans for cervix cancer.Methods:39 patients with cervical cancer after surgery were randomly selected, 20 patient plans were used to create the model, the other 19 cases used for comparative evaluation. All plans were designed in Eclipse system. The prescription dose was 30.6Gy, 17 fractions, OARs dose satisfied to the clinical requirement. A paired t test was used to evaluate the differences of dose‐volume histograms (DVH).Results:Comparaed to C‐IMRT plan, the KBRT plan target can achieve the similar target dose coverage, D98,D95,D2,HI and CI had no difference (P≥0.05). The dose of rectum, bladder and femoral heads had no significant differences(P≥0.05). The time was used to design treatment plan was significant reduced.Conclusion:This study shows that postoperative radiotherapy of cervical KBRT plans can achieve the similar target and OARs dose, but the shorter designing time.
SU‐E‐P‐59: A Graphical Interface for XCAT Phantom Configuration, Generation and Processing
Authors: Myronakis M , Cai W , Dhou S , Cifter F , Hurwitz M , Lewis J 
Published: June 2015

Purpose:To design a comprehensive open‐source, publicly available, graphical user interface (GUI) to facilitate the configuration, generation, processing and use of the 4D Extended Cardiac‐Torso (XCAT) phantom.Methods:The XCAT phantom includes over 9000 anatomical objects as well as respiratory, cardiac and tumor motion. It is widely used for research studies in medical imaging and radiotherapy. The phantom generation process involves the configuration of a text script to parameterize the geometry, motion, and composition of the whole body and objects within it, and to generate simulated PET or CT images. To avoid the need for manual editing or script writing, our MATLAB‐based GUI uses slider controls, drop‐down lists, buttons and graphical text input to parameterize and process the phantom.Results:Our GUI can be used to: a) generate parameter files; b) generate the voxelized phantom; c) combine the phantom with a lesion; d) display the phantom; e) produce average and maximum intensity images from the phantom output files; f) incorporate irregular patient breathing patterns; and f) generate DICOM files containing phantom images. The GUI provides local help information using tool‐tip strings on the currently selected phantom, minimizing the need for external documentation. The DICOM generation feature is intended to simplify the process of importing the phantom images into radiotherapy treatment planning systems or other clinical software.Conclusion:The GUI simplifies and automates the use of the XCAT phantom for imaging‐based research projects in medical imaging or radiotherapy. This has the potential to accelerate research conducted with the XCAT phantom, or to ease the learning curve for new users. This tool does not include the XCAT phantom software itself.We would like to acknowledge funding from MRA, Varian Medical Systems Inc.
SU‐E‐U‐02: The Development of a Practical Ultrasonic System for Cross‐Sectional Imaging of Small Animals
Authors: Kamp J , Malyarenko E , Chen D , Wydra A , Maev R 
Published: June 2015

Purpose:To test the feasibility of developing a practical medium frequency ultrasound tomography method for small animal imaging. The ability to produce cross‐sectional or full body images of a live small animal using a low‐cost tabletop ultrasound scanner without any special license would be very beneficial to long term biological studies, where repeated scanning is often required over an extended period of time.Methods:The cross sectional images were produced by compounding multiple B‐scans of a laboratory phantom or an animal acquired at different projection angles. Two imaging systems were used to test the concept. The first system included a programmable 64‐channel phased array controller driving a 128‐channel, 5–10 MHz linear probe to produce 143 B‐Mode projections of the spinning object. The second system designed and manufactured in house, produced 64 or 128 B‐Mode projections with a single unfocused 8 MHz transducer scanning with a 0.116 mm step size.Results:The phased array system provided good penetration through the phantoms/mice (with the exception of the lungs) and allowed to acquire data in a very short time. The cross‐sectional images have enough resolution and dynamic range to detect both high‐ and low‐contrast organs. The single transducer system takes longer to scan, and the data require more sophisticated processing. To date, our images allow seeing details as small as 1–2 mm in the phantoms and in small animals, with the contrast mostly due to highly reflecting bones and air inclusions.Conclusion:The work indicates that very detailed and anatomically correct images can be created by relatively simple and inexpensive means. With more advanced algorithms and improved system design, scan time can be reduced considerably, enabling high‐resolution full 3D imaging. This will allow for quick and easy scans that can help monitor tumor growth and/or regression without contributing any dose to the animal.The authors would like to acknowledge the financial and engineering support from Tessonics.
SU‐E‐I‐04: Improving CT Quality for Radiation Therapy of Patients with High Body Mass Index Using Iterative Reconstruction Algorithms
Authors: Noid G , Tai A , Li X 
Published: June 2015

Purpose:Iterative reconstruction (IR) algorithms are developed to improve CT image quality (IQ) by reducing noise without diminishing spatial resolution or contrast. The CT IQ for patients with a high Body Mass Index (BMI) can suffer from increased noise due to photon starvation. The purpose of this study is to investigate and to quantify the IQ enhancement for high BMI patients through the application of IR algorithms.Methods:CT raw data collected for 6 radiotherapy (RT) patients with BMI, greater than or equal to 30 were retrospectively analyzed. All CT data were acquired using a CT scanner (Somaton Definition AS Open, Siemens) installed in a linac room (CT‐on‐rails) using standard imaging protocols. The CT data were reconstructed using the Sinogram Affirmed Iterative Reconstruction (SAFIRE) and Filtered Back Projection (FBP) methods. IQ metrics of the obtained CTs were compared and correlated with patient depth and BMI. The patient depth was defined as the largest distance from anterior to posterior along the bilateral symmetry axis.Results:IR techniques are demonstrated to preserve contrast and reduce noise in comparison to traditional FBP. Driven by the reduction in noise, the contrast to noise ratio is roughly doubled by adopting the highest SAFIRE strength. A significant correlation was observed between patient depth and IR noise reduction through Pearson's correlation test (R = 0.9429/P = 0.0167). The mean patient depth was 30.4 cm and the average relative noise reduction for the strongest iterative reconstruction was 55%.Conclusion:The IR techniques produce a measureable enhancement to CT IQ by reducing the noise. Dramatic noise reduction is evident for the high BMI patients. The improved CT IQ enables more accurate delineation of tumors and organs at risk and more accuarte dose calculations for RT planning and delivery guidance.Supported by Siemens
SU‐E‐I‐05: A Correction Algorithm for Kilovoltage Cone‐Beam Computed Tomography Dose Calculations in Cervical Cancer Patients
Authors: Zhang J , Zhang W , Lu J 
Published: June 2015

Purpose:To investigate the accuracy and feasibility of dose calculations using kilovoltage cone beam computed tomography in cervical cancer radiotherapy using a correction algorithm.Methods:The Hounsfield units (HU) and electron density (HU‐density) curve was obtained for both planning CT (pCT) and kilovoltage cone beam CT (CBCT) using a CIRS‐062 calibration phantom. The pCT and kV‐CBCT images have different HU values, and if the HU‐density curve of CBCT was directly used to calculate dose in CBCT images may have a deviation on dose distribution. It is necessary to normalize the different HU values between pCT and CBCT. A HU correction algorithm was used for CBCT images (cCBCT). Fifteen intensity‐modulated radiation therapy (IMRT) plans of cervical cancer were chosen, and the plans were transferred to the pCT and cCBCT data sets without any changes for dose calculations. Phantom and patient studies were carried out. The dose differences and dose distributions were compared between cCBCT plan and pCT plan.Results:The HU number of CBCT was measured by several times, and the maximum change was less than 2%. To compare with pCT, the CBCT and cCBCT has a discrepancy, the dose differences in CBCT and cCBCT images were 2.48%±0.65% (range: 1.3%∼3.8%) and 0.48%±0.21% (range: 0.1%∼0.82%) for phantom study, respectively. For dose calculation in patient images, the dose differences were 2.25%±0.43% (range: 1.4%∼3.4%) and 0.63%±0.35% (range: 0.13%∼0.97%), respectively. And for the dose distributions, the passing rate of cCBCT was higher than the CBCTs.Conclusion:The CBCT image for dose calculation is feasible in cervical cancer radiotherapy, and the correction algorithm offers acceptable accuracy. It will become a useful tool for adaptive radiation therapy.
SU‐E‐I‐06: A Dose Calculation Algorithm for KV Diagnostic Imaging Beams by Empirical Modeling
Authors: Chacko M , Aldoohan S , Sonnad J , Ahmad S , Ali I 
Published: June 2015

Purpose:To develop accurate three‐dimensional (3D) empirical dose calculation model for kV diagnostic beams for different radiographic and CT imaging techniques.Methods:Dose was modeled using photon attenuation measured using depth dose (DD), scatter radiation of the source and medium, and off‐axis ratio (OAR) profiles. Measurements were performed using single‐diode in water and a diode‐array detector (MapCHECK2) with kV on‐board imagers (OBI) integrated with Varian TrueBeam and Trilogy linacs. The dose parameters were measured for three energies: 80, 100, and 125 kVp with and without bowtie filters using field sizes 1×1–40×40 cm2 and depths 0–20 cm in water tank.Results:The measured DD decreased with depth in water because of photon attenuation, while it increased with field size due to increased scatter radiation from medium. DD curves varied with energy and filters where they increased with higher energies and beam hardening from half‐fan and full‐fan bowtie filters. Scatter radiation factors increased with field sizes and higher energies. The OAR was with 3% for beam profiles within the flat dose regions. The heal effect of this kV OBI system was within 6% from the central axis value at different depths. The presence of bowtie filters attenuated measured dose off‐axis by as much as 80% at the edges of large beams. The model dose predictions were verified with measured doses using single point diode and ionization chamber or two‐dimensional diode‐array detectors inserted in solid water phantoms.Conclusion:This empirical model enables fast and accurate 3D dose calculation in water within 5% in regions with near charge‐particle equilibrium conditions outside buildup region and penumbra. It considers accurately scatter radiation contribution in water which is superior to air‐kerma or CTDI dose measurements used usually in dose calculation for diagnostic imaging beams. Considering heterogeneity corrections in this model will enable patient specific dose calculation.
SU‐E‐I‐08: Investigation of Deconvolution Methods for Blocker‐Based CBCT Scatter Estimation
Authors: Zhao C , Ouyang L , Wang J , Jin M 
Published: June 2015

Purpose:To investigate whether deconvolution methods can improve the scatter estimation under different blurring and noise conditions for blocker‐based scatter correction methods for cone‐beam X‐ray computed tomography (CBCT).Methods:An “ideal” projection image with scatter was first simulated for blocker‐based CBCT data acquisition by assuming no blurring effect and no noise. The ideal image was then convolved with long‐tail point spread functions (PSF) with different widths to mimic the blurring effect from the finite focal spot and detector response. Different levels of noise were also added. Three deconvolutionMethods:1) inverse filtering; 2) Wiener; and 3) Richardson‐Lucy, were used to recover the scatter signal in the blocked region. The root mean square error (RMSE) of estimated scatter serves as a quantitative measure for the performance of different methods under different blurring and noise conditions.Results:Due to the blurring effect, the scatter signal in the blocked region is contaminated by the primary signal in the unblocked region. The direct use of the signal in the blocked region to estimate scatter (“direct method”) leads to large RMSE values, which increase with the increased width of PSF and increased noise. The inverse filtering is very sensitive to noise and practically useless. The Wiener and Richardson‐Lucy deconvolution methods significantly improve scatter estimation compared to the direct method. For a typical medium PSF and medium noise condition, both methods (∼20 RMSE) can achieve 4‐fold improvement over the direct method (∼80 RMSE). The Wiener method deals better with large noise and Richardson‐Lucy works better on wide PSF.Conclusion:We investigated several deconvolution methods to recover the scatter signal in the blocked region for blocker‐based scatter correction for CBCT. Our simulation results demonstrate that Wiener and Richardson‐Lucy deconvolution can significantly improve the scatter estimation compared to the direct method.
SU‐E‐I‐10: Investigation On Detectability of a Small Target for Different Slice Direction of a Volumetric Cone Beam CT Image
Authors: Lee C , Han M , Baek J 
Published: June 2015

Purpose:To investigate the detectability of a small target for different slice direction of a volumetric cone beam CT image and its impact on dose reduction.Methods:Analytic projection data of a sphere object (1 mm diameter, 0.2/cm attenuation coefficient) were generated and reconstructed by FDK algorithm. In this work, we compared the detectability of the small target from four different backprojectionMethods:hanning weighted ramp filter with linear interpolation (RECON 1), hanning weighted ramp filter with Fourier interpolation (RECON2), ramp filter with linear interpolation (RECON 3), and ramp filter with Fourier interpolation (RECON4), respectively. For noise simulation, 200 photons per measurement were used, and the noise only data were reconstructed using FDK algorithm. For each reconstructed volume, axial and coronal slice were extracted and detection‐SNR was calculated using channelized Hotelling observer (CHO) with dense difference‐of‐Gaussian (D‐DOG) channels.Results:Detection‐SNR of coronal images varies for different backprojection methods, while axial images have a similar detection‐SNR. Detection‐SNR2 ratios of coronal and axial images in RECON1 and RECON2 are 1.33 and 1.15, implying that the coronal image has a better detectability than axial image. In other words, using coronal slices for the small target detection can reduce the patient dose about 33% and 15% compared to using axial slices in RECON 1 and RECON 2.Conclusion:In this work, we investigated slice direction dependent detectability of a volumetric cone beam CT image. RECON 1 and RECON 2 produced the highest detection‐SNR, with better detectability in coronal slices. These results indicate that it is more beneficial to use coronal slice to improve detectability of a small target in a volumetric cone beam CT image.This research was supported by the MSIP (Ministry of Science, ICT and Future Planning), Korea, under the IT Consilience Creative Program (NIPA‐2014‐H0201‐14‐1002) supervised by the NIPA (National IT Industry Promotion Agency). Authors declares that s/he has no conflict of Interest in relation to the work in this abstract.