bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐E‐I‐21: Dosimetric Characterization and Image Quality Evaluation of the AIRO Mobile CT Scanner
Authors: Weir V , Zhang J , Bruner A 
Published: June 2015

Purpose:The AIRO Mobile CT system was recently introduced which overcomes the limitations from existing CT, CT fluoroscopy, and intraoperative O‐arm. With an integrated table and a large diameter bore, the system is suitable for cranial, spine and trauma procedures, making it a highly versatile intraoperative imaging system. This study is to investigate radiation dose and image quality of the AIRO and compared with those from a routine CT scanner.Methods:Radiation dose was measured using a conventional 100mm pencil ionization chamber and CT polymethylmetacrylate (PMMA) body and head phantoms. Image quality was evaluated with a CATPHAN 500 phantom. Spatial resolution, low contrast resolution (CNR), Modulation Transfer Function (MTF), and Normalized Noise Power Spectrum (NNPS) were analyzed.Results:Under identical technique conditions, radiation dose (mGy/mAs) from the AIRO mobile CT system (AIRO) is higher than that from a 64 slice CT scanner. MTFs show that both Soft and Standard filters of the AIRO system lost resolution quickly compared to the Sensation 64 slice CT. With the Standard kernel, the spatial resolutions of the AIRO system are 3lp/cm and 4lp/cm for the body and head FOVs, respectively. NNPSs show low frequency noise due to ring‐like artifacts. Due to a higher dose in terms of mGy/mAs at both head and body FOV, CNR of the AIRO system is higher than that of the Siemens scanner. However detectability of the low contrast objects is poorer in the AIRO due to the presence of ring artifacts in the location of the targets.Conclusion:For image guided surgery applications, the AIRO has some advantages over a routine CT scanner due to its versatility, large bore size, and acceptable image quality. Our evaluation of the physical performance helps its future improvements.
SU‐E‐I‐22: A Comprehensive Investigation of Noise Variations Between the GE Discovery CT750 HD and GE LightSpeed VCT
Authors: Bache S , Loyer E , Stauduhar P , Liu X , Rong J 
Published: June 2015

Purpose:To quantify and compare the noise properties between two GE CT models‐the Discovery CT750 HD (aka HD750) and LightSpeed VCT, with the overall goal of assessing the impact in clinical diagnostic practice.Methods:Daily QC data from a fleet of 9 CT scanners currently in clinical use were investigated – 5 HD750 and 4 VCT (over 600 total acquisitions for each scanner). A standard GE QC phantom was scanned daily using two sets of scan parameters with each scanner over 1 year. Water CT number and standard deviation were recorded from the image of water section of the QC phantom. The standard GE QC scan parameters (Pitch = 0.516, 120kVp, 0.4s, 335mA, Small Body SFOV, 5mm thickness) and an in‐house developed protocol (Axial, 120kVp, 1.0s, 240mA, Head SFOV, 5mm thickness) were used, with Standard reconstruction algorithm. Noise was measured as the standard deviation in the center of the water phantom image. Inter‐model noise distributions and tube output in mR/mAs were compared to assess any relative differences in noise properties.Results:With the in‐house protocols, average noise for the five HD750 scanners was ∼9% higher than the VCT scanners (5.8 vs 5.3). For the GE QC protocol, average noise with the HD750 scanners was ∼11% higher than with the VCT scanners (4.8 vs 4.3). This discrepancy in noise between the two models was found despite the tube output in mR/mAs being comparable with the HD750 scanners only having ∼4% lower output (8.0 vs 8.3 mR/mAs).Conclusion:Using identical scan protocols, average noise in images from the HD750 group was higher than that from the VCT group. This confirms feedback from an institutional radiologist's feedback regarding grainier patient images from HD750 scanners. Further investigation is warranted to assess the noise texture and distribution, as well as clinical impact.
SU‐E‐I‐85: Absorbed Dose Estimation for a Commercially Available MicroCT Scanner
Authors: Lau A , Ren L , Liu H , Yang K , Ahmad S , Chen Y 
Published: June 2015

Purpose:To quantify the simulated absorbed dose delivered for a typical scan from a commercially available microCT scanner in order to aid in the dose estimation.Methods:The simulations were conducted using the Geant4 Monte Carlo Toolkit (version 10) with the standard electromagnetic classes. The Quantum FX microCT scanner (PerkinElmer, Waltham, MA) was modeled incorporating the energy fluence and angular distributions of generated photons, spatial dimensions of nominal source‐to‐object and source‐to‐detector distances. The energy distribution was measured using a spectrometer (X‐123CdTe, Amptek Inc., Bedford, USA) with a 300 angular spread from the source for the 90 kVp X‐ray beams with no additional filtration. The nominal distances from the source to object consisted of three setups: 154.0 mm, 104.0 mm, and 51.96 mm. Our simulations recorded the dose absorbed in a cylindrical phantom of PMMA with a fixed length of 2 cm and varying radii (10, 20, 30 and 40 mm) using 100 million incident photons. The averaged absorbed dose in the object was then quantified for all setups. An exposure measurement of 417 mR was taken using a Radcal 9095 system utilizing 10×9–180 ion chamber with the given technique of 90 kVp, 63 μA, and 12 s. The exposure rate was also simulated with same setup to calculate the conversion factor of the beam current and the number of incident photons.Results:For a typical cone‐beam scan with non‐filtered 90kVp, the dose coefficients (the absorbed dose per mAs) were 2.614, 2.549 and 2.467 μGy/mAs under source to object distance of 104 mm for the object diameters of 10 mm, 20 mm and 30 mm, respectively.Conclusion:A look‐up table was developed where an investigator can estimate the delivered dose using this particular microCT given the scanning protocol (kVp and mAs) as well as the size of the scanned object.
SU‐E‐J‐04: Integration of Interstitial High Intensity Therapeutic Ultrasound Applicators On a Clinical MRI‐Guided High Intensity Focused Ultrasound Treatment Planning Software Platform
Authors: Ellens N , Partanen A , Ghoshal G , Burdette E , Farahani K 
Published: June 2015

Purpose:Interstitial high intensity therapeutic ultrasound (HITU) applicators can be used to ablate tissue percutaneously, allowing for minimally‐invasive treatment without ionizing radiation [1,2]. The purpose of this study was to evaluate the feasibility and usability of combining multielement interstitial HITU applicators with a clinical magnetic resonance imaging (MRI)‐guided focused ultrasound software platform.Methods:The Sonalleve software platform (Philips Healthcare, Vantaa, Finland) combines anatomical MRI for target selection and multi‐planar MRI thermometry to provide real‐time temperature information. The MRI‐compatible interstitial US applicators (Acoustic MedSystems, Savoy, IL, USA) had 1–4 cylindrical US elements, each 1 cm long with either 180° or 360° of active surface. Each applicator (4 Fr diameter, enclosed within a 13 Fr flexible catheter) was inserted into a tissue‐mimicking agar‐silica phantom. Degassed water was circulated around the transducers for cooling and coupling. Based on the location of the applicator, a virtual transducer overlay was added to the software to assist targeting and to allow automatic thermometry slice placement. The phantom was sonicated at 7 MHz for 5 minutes with 6–8 W of acoustic power for each element. MR thermometry data were collected during and after sonication.Results:Preliminary testing indicated that the applicator location could be identified in the planning images and the transducer locations predicted within 1 mm accuracy using the overlay. Ablation zones (thermal dose ≥ 240 CEM43) for 2 active, adjacent US elements ranged from 18 mm × 24 mm (width × length) to 25 mm × 25 mm for the 6 W and 8 W sonications, respectively.Conclusion:The combination of interstitial HITU applicators and this software platform holds promise for novel approaches in minimally‐invasive MRI‐guided therapy, especially when bony structures or air‐filled cavities may preclude extracorporeal HIFU.[1] Diederich et al. IEEE UFFFC 46.5 (1999): 1218.[2] Chopra et al. PMB 50.21 (2005): 4957.Funding support was provided by Philips Healthcare and in‐kind support from Acoustic MedSystems Inc. Ari Partanen is a paid employee of Philips Healthcare. Goutam Ghoshal and Everette Clif Burdette are paid employees of Acoustic MedSystems Inc.
SU‐E‐J‐10: Imaging Dose and Cancer Risk in Image‐Guided Radiotherapy of Cancers
Authors: Zhou L , Bai S , Zhang Y , Deng J 
Published: June 2015

Purpose:To systematically evaluate imaging doses and cancer risks to organs‐at‐risk as a Result of cumulative doses from various radiological imaging procedures in image‐guided radiotherapy (IGRT) in a large cohort of cancer patients.Methods:With IRB approval, imaging procedures (computed tomography, kilo‐voltage portal imaging, megavoltage portal imaging and kilo‐voltage cone‐beam computed tomography) of 4832 cancer patients treated during 4.5 years were collected with their gender, age and circumference. Correlations between patient's circumference and Monte Carlo simulated‐organ dose were applied to estimate organ doses while the cancer risks were reported as 1+ERR using BEIR VII models.Results:80 cGy or more doses were deposited to brain, lungs and RBM in 273 patients (maximum 136, 278 and 267 cGy, respectively), due largely to repetitive imaging procedures and non‐personalized imaging settings. Regardless of gender, relative cancer risk estimates for brain, lungs, and RBM were 3.4 (n = 55), 2.6 (n = 49), 1.8 (n = 25) for age group of 0–19; 1.2 (n = 87), 1.4 (n = 98), 1.3 (n = 51) for age group of 20–39; 1.0 (n = 457), 1.1 (n = 880), 1.8 (n=360) for age group of 40–59; 1.0 (n = 646), 1.1 (n = 1400), 2.3 (n = 716) for age group of 60–79 and 1.0 (n = 108),1.1 (n = 305),1.6 (n = 147) for age group of 80–99.Conclusion:The cumulative imaging doses and associated cancer risks from multi‐imaging procedures were patient‐specific and site‐dependent, with up to 2.7 Gy imaging dose deposited to critical structures in some pediatric patients. The associated cancer risks in brain and lungs for children of age 0 to 19 were 2–3 times larger than those for adults. This study indicated a pressing need for personalized imaging protocol to maximize its clinical benefits while reducing associated cancer risks.Sichuan University Scholarship
SU‐E‐J‐12: An Image‐Guided Soft Robotic Patient Positioning System for Maskless Head‐And‐Neck Cancer Radiotherapy: A Proof‐Of‐Concept Study
Authors: Ogunmolu O , Gans N , Jiang S , Gu X 
Published: June 2015

Purpose:We propose a surface‐image‐guided soft robotic patient positioning system for maskless head‐and‐neck radiotherapy. The ultimate goal of this project is to utilize a soft robot to realize non‐rigid patient positioning and real‐time motion compensation. In this proof‐of‐concept study, we design a position‐based visual servoing control system for an air‐bladder‐based soft robot and investigate its performance in controlling the flexion/extension cranial motion on a mannequin head phantom.Methods:The current system consists of Microsoft Kinect depth camera, an inflatable air bladder (IAB), pressured air source, pneumatic valve actuators, custom‐built current regulators, and a National Instruments myRIO microcontroller. The performance of the designed system was evaluated on a mannequin head, with a ball joint fixed below its neck to simulate torso‐induced head motion along flexion/extension direction. The IAB is placed beneath the mannequin head. The Kinect camera captures images of the mannequin head, extracts the face, and measures the position of the head relative to the camera. This distance is sent to the myRIO, which runs control algorithms and sends actuation commands to the valves, inflating and deflating the IAB to induce head motion.Results:For a step input, i.e. regulation of the head to a constant displacement, the maximum error was a 6% overshoot, which the system then reduces to 0% steady‐state error. In this initial investigation, the settling time to reach the regulated position was approximately 8 seconds, with 2 seconds of delay between the command start of motion due to capacitance of the pneumatics, for a total of 10 seconds to regulate the error.Conclusion:The surface image‐guided soft robotic patient positioning system can achieve accurate mannequin head flexion/extension motion. Given this promising initial Result, the extension of the current one‐dimensional soft robot control to multiple IABs for non‐rigid positioning control will be pursued.
SU‐E‐J‐13: Six Degree of Freedom Image Fusion Accuracy for Cranial Target Localization On the Varian Edge Stereotactic Radiosurgery System: Comparison Between 2D/3D and KV CBCT Image Registration
Authors: Xu H , Song K , Chetty I , Wen N , Kim J 
Published: June 2015

Purpose:To determine the 6 degree of freedom systematic deviations between 2D/3D and CBCT image registration with various imaging setups and fusion algorithms on the Varian Edge Linac.Methods:An anthropomorphic head phantom with radio opaque targets embedded was scanned with CT slice thicknesses of 0.8, 1, 2, and 3mm. The 6 DOF systematic errors were assessed by comparing 2D/3D (kV/MV with CT) with 3D/3D (CBCT with CT) image registrations with different offset positions, similarity measures, image filters, and CBCT slice thicknesses (1 and 2 mm). The 2D/3D registration accuracy of 51 fractions for 26 cranial SRS patients was also evaluated by analyzing 2D/3D pre‐treatment verification taken after 3D/3D image registrations.Results:The systematic deviations of 2D/3D image registration using kV‐ kV, MV‐kV and MV‐MV image pairs were within ±0.3mm and ±0.3° for translations and rotations with 95% confidence interval (CI) for a reference CT with 0.8 mm slice thickness. No significant difference (P>0.05) on target localization was observed between 0.8mm, 1mm, and 2mm CT slice thicknesses with CBCT slice thicknesses of 1mm and 2mm. With 3mm CT slice thickness, both 2D/3D and 3D/3D registrations performed less accurately in longitudinal direction than thinner CT slice thickness (0.60±0.12mm and 0.63±0.07mm off, respectively). Using content filter and using similarity measure of pattern intensity instead of mutual information, improved the 2D/3D registration accuracy significantly (P=0.02 and P=0.01, respectively). For the patient study, means and standard deviations of residual errors were 0.09±0.32mm, −0.22±0.51mm and −0.07±0.32mm in VRT, LNG and LAT directions, respectively, and 0.12°±0.46°, −0.12°±0.39° and 0.06°±0.28° in RTN, PITCH, and ROLL directions, respectively. 95% CI of translational and rotational deviations were comparable to those in phantom study.Conclusion:2D/3D image registration provided on the Varian Edge radiosurgery, 6 DOF‐based system provides accurate target positioning for frameless image‐guided cranial stereotactic radiosurgery.
SU‐E‐J‐14: A Comparison of a 2.5MV Imaging Beam to KV and 6MV Imaging Beams
Authors: Nitsch P , Robertson D , Balter P 
Published: June 2015

Purpose:To compare image quality metrics and dose of TrueBeam V2.0's 2.5MV imaging beam and kV and 6MV images.Methods:To evaluate the MV image quality, the Standard Imaging QC‐3 and Varian Las Vegas (LV) phantoms were imaged using the ‘quality’ and ‘low dose’ modes and then processed using RIT113 V6.3. The LEEDS phantom was used to evaluate the kV image quality. The signal to noise ratio (SNR) was also evaluated in patient images using Matlab. In addition, dose per image was evaluated at a depth of 5cm using solid water for a 28.6 cm × 28.6 cm field size, which is representative of the largest jaw settings at an SID of 150cm.Results:The 2.5MV images had lower dose than the 6 MV images and a contrast to noise ratio (CNR) about 1.4 times higher, when evaluated using the QC‐3. When energy was held constant but dose varied, the different modes, ‘low dose’ and ‘quality’, showed less than an 8% difference in CNR. The ‘quality’ modes demonstrated better spatial resolution than the ‘low dose’; however, even with the ‘low dose’ all line pairs were distinct except for the 0.75lp/mm on the 2.5MV. The LV phantom was used to measure low contrast detectability and showed similar results to the QC‐3. Several patient images all confirmed that SNR were highest in kV images followed by 2.5MV and then 6MV. Qualitatively, for anatomical areas with large variability in thickness, like lateral head and necks, 2.5MV images show more anatomy, such as shoulder position, than kV images.Conclusions:The kV images clearly provide the best image metrics per unit dose. The 2.5MV beam showed excellent contrast at a lower dose than 6MV and may be superior to kV for difficult to image areas that include large changes in anatomical thickness.P Balter: Varian, Sun Nuclear, Philips, CPRIT
SU‐E‐J‐19: An Intra‐Institutional Study of Cone‐Beam CT Dose for Image‐Guided Radiation Therapy
Authors: Knutson N , Rankine L , Reilly M , Li H 
Published: June 2015

Purpose:To determine the variability of Cone‐Beam CT Dose Index (CB‐CTDI) across multiple on‐board imaging (OBI) systems within a single institution, and compare this to manufacturer provided data.Methods:The CB‐CTDI was measured on three Trilogy and three TrueBeam Varian OBI systems, for six different clinically used scan protocols. Measurements were taken using a 10 cm long CT ionization chamber in either a 16 cm (head‐simulating) or 32 cm (body‐simulating) diameter, acrylic, cylindrical, 15 cm long CTDI phantom. We assessed the variation in CB‐CTDI between the OBI systems and compared our measured values to the data provided by the manufacturer.Results:The standard error in the CB‐CTDI measured for all protocols was found to be within ±2% and ±5% of the mean for TrueBeam and Trilogy, respectively. For all head scan protocols, the measured TrueBeam values were lower than the manufacturer's reported values, with a maximum difference of 13.9% and an average difference of 11%. For the body scan protocols, the TrueBeam measured values were 3% and 13% greater than the manufacturer's reported values for two out of three protocols, and 38% lower than reported for the third protocol. In total, 7/18 CB‐CTDI measurements fell within the manufacturers specified range (±10%). Across all scans the Truebeam machines were found to have a lower CB‐CTDI than Trilogy, particularly the head scan protocols, which show decreases of up to 30% .Conclusion:The intra‐institutional variation of CB‐CTDI was found to be clinically acceptable at less than 5%. For the TrueBeam OBI system, over half of the measured scans failed to fall with in the manufactured quoted range of 10%, however, all measured values were within 15% of the manufacturer's reported values. For accurate assessment and reporting of imaging dose to radiotherapy patients, our results indicate a need for standardization in CB‐CTDI measurement technique.
SU‐E‐J‐20: Identifying Predictors for Translational and Rotational Shifts of Liver SBRT Patients
Authors: Powers A , Sheu R , Blacksburg S 
Published: June 2015

Purpose:Identifying predictors of translational and rotational offsets for liver SBRT treatment may be of assistance in determining if the use of a 6D couch is more advantageous for particular patients.Methods:From February 2013 to February 2015, 85 patients received liver SBRT for HCC or metastases. CBCT imaging was used for each patient and offsets recorded. There were 399 initial CBCT registrations performed. 184 registrations contained angular offsets. The mean offsets for patients in the superior/inferior, anterior/posterior, and lateral dimension were 4mm, 4mm, and 3mm, respectively. The mean absolute angular yaw, pitch, and roll were 0.2°, 0.3°, and 0.3°, respectively. Mean GTV, PTV, and Liver volume was 46.6, 153.3, and 1435.2cc's. 59 patients were male and the mean body mass index (BMI) was 27.2kg/m2. Hepatic segments were characterized as anterior/posterior left/right, superior/inferior, or lateral/medial by established anatomic classification. Chi‐squared test and Multinomial Logistic Regression were used for univariate (UVA) and multivariate (MVA) analyses.Results:Offsets ≥ 2mm, 5mm, and 10mm occurred 82.5%, 49.4%, and 9.5% of the time, respectively. While kV imaging prior to CBCT decreased the frequency of 2 and 5mm offsets on UVA, on MVA BMI's >20 predicted for offsets. On UVA and MVA, lateral lesions were more likely to have ≥ 10mm shift. Offsets ≥ 0.2°, 0.5°, and 1° occurred 76.1%, 68.5%, and 42.9% of the time, respectively. Lateral lesions were more likely on MVA to experience ≥ 0.2° and 0.5° shifts, while previous kV images were the only variable that predicted for shift < 1°. No dosimetric parameter predicted for translation or rotation offsets on MVA.Conclusion:BMIs <20 predict for smaller translations during liver SBRT, while lateral lesions predict for greater translation and rotation offsets. Patients treated with lateral lesions might benefit more from the angular capability of a 6D couch.
SU‐E‐J‐25: End‐To‐End (E2E) Testing On TomoHDA System Using a Real Pig Head for Intracranial Radiosurgery
Authors: Corradini N , Leick M , Bonetti M , Negretti L 
Published: June 2015

Purpose:To determine the MVCT imaging uncertainty on the TomoHDA system for intracranial radiosurgery treatments. To determine the end‐to‐end (E2E) overall accuracy of the TomoHDA system for intracranial radiosurgery.Methods:A pig head was obtained from the butcher, cut coronally through the brain, and preserved in formaldehyde. The base of the head was fixed to a positioning plate allowing precise movement, i.e. translation and rotation, in all 6 axes. A repeatability test was performed on the pig head to determine uncertainty in the image bone registration algorithm. Furthermore, the test studied images with MVCT slice thicknesses of 1 and 3 mm in unison with differing scan lengths. A sensitivity test was performed to determine the registration algorithm's ability to find the absolute position of known translations/rotations of the pig head. The algorithm's ability to determine absolute position was compared against that of manual operators, i.e. a radiation therapist and radiation oncologist. Finally, E2E tests for intracranial radiosurgery were performed by measuring the delivered dose distributions within the pig head using Gafchromic films.Results:The repeatability test uncertainty was lowest for the MVCTs of 1‐mm slice thickness, which measured less than 0.10 mm and 0.12 deg for all axes. For the sensitivity tests, the bone registration algorithm performed better than human eyes and a maximum difference of 0.3 mm and 0.4 deg was observed for the axes. E2E test results in absolute position difference measured 0.03 ± 0.21 mm in x‐axis and 0.28 ± 0.18 mm in y‐axis. A maximum difference of 0.32 and 0.66 mm was observed in × and y, respectively. The average peak dose difference between measured and calculated dose was 2.7 cGy or 0.4%.Conclusion:Our tests using a pig head phantom estimate the TomoHDA system to have a submillimeter overall accuracy for intracranial radiosurgery.