bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐E‐J‐108: Template Matching Based On Multiple Templates Can Improve the Tumor Tracking Performance When There Is Large Tumor Deformation
Authors: Shi X , Lin J , Diwanji T , Mooney K , D' Souza W , Mistry N 
Published: July 2014

Purpose:Recently, template matching has been shown to be able to track tumor motion on cine‐MRI images. However, artifacts such as deformation, rotation, and/or out‐of‐plane movement could seriously degrade the performance of this technique. In this work, we demonstrate the utility of multiple templates derived from different phases of tumor motion in reducing the negative effects of artifacts and improving the accuracy of template matching methods.Methods:Data from 2 patients with large tumors and significant tumor deformation were analyzed from a group of 12 patients from an earlier study. Cine‐MRI (200 frames) imaging was performed while the patients were instructed to breathe normally. Ground truth tumor position was established on each frame manually by a radiation oncologist. Tumor positions were also automatically determined using template matching with either single or multiple (5) templates. The tracking errors, defined as the absolute differences in tumor positions determined by the manual and automated methods, when using either single or multiple templates were compared in both the AP and SI directions, respectively.Results:Using multiple templates reduced the tracking error of template matching. In the SI direction where the tumor movement and deformation were significant, the mean tracking error decreased from 1.94 mm to 0.91 mm (Patient 1) and from 6.61 mm to 2.06 mm (Patient 2). In the AP direction where the tumor movement was small, the reduction of the mean tracking error was significant in Patient 1 (from 3.36 mm to 1.04 mm), but not in Patient 2 (from 3.86 mm to 3.80 mm).Conclusion:This study shows the effectiveness of using multiple templates in improving the performance of template matching when artifacts like large tumor deformation or out‐of‐plane motion exists. Accurate tumor tracking capabilities can be integrated with MRI guided radiation therapy systems.This work was supported in part by grants from NIH/NCI CA 124766 and Varian Medical Systems, Palo Alto, CA.
SU‐E‐J‐111: The Contouring Error of the Parotids Based On the CT and MRI Images in Radiotherapy Planning for Nasopharyngeal Carcinoma
Authors: Gong G , Liu C 
Published: July 2014

Purpose:To analyze the variation of sketching the parotid for patients with nasopharyngeal carcinoma who underwent radiotherapy based on computed tomography (CT) and magnetic resonance(MR) images.Methods:41 nasopharyngeal cancer patients were randomly selected. Each patient underwent MR and CT scanning. The Gross Tumor Volume and Organs at risk were contoured on both contrasted CT and T1‐MR images. For each patient, one radiotherapist sketched the parotid on CT and MR images for 10 times, and 10 different radiotherapists were asked to sketching the parotid on CT and MR images only one time. The inter‐ and intra‐observers volumes and outline variations were compared.Results:The volumes of parotid contoured by inter‐observer on CT and MR images were 34.6±12.1cm3(left),34.3±9.0cm3(right) and 24.6±7.6cm3(L),23.2±8.1cm3(R); In the same way, for intra‐observer on CT and MR images the volumes were 28.2±7.6cm3(L),29.4±9.4cm3(R) and 24.4±7.6cm3(L),22.5±7.4cm3(R), respectively. The variable ratios of volume on MR images were 4.7±0.7%(L),5.0±0.6%(R) for inter‐observer and 2.3±0.4%(L),2.1±0.7%(R) for intra‐observer. Similarly, The inter‐ and intra‐observer ratios for contouring on CT images reached 18.0±4.8%(L),17.4±4.6%(R) and 6.3±1.5%(L),6.8±1.5%(R), respectively.Conclusion:Contouring the parotids on MR images was more accurate and reproducible than that on CT images.
SU‐E‐J‐114: Towards Integrated CT and Ultrasound Guided Radiation Therapy Using A Robotic Arm with Virtual Springs
Authors: Ding K , Zhang Y , Sen H , Lediju Bell M , Goldstein S , Kazanzides P , Iordachita I , Wong J 
Published: July 2014

Purpose:Currently there is an urgent need in Radiation Therapy for noninvasive and nonionizing soft tissue target guidance such as localization before treatment and continuous monitoring during treatment. Ultrasound is a portable, low cost option that can be easily integrated with the LINAC room. We are developing a cooperatively controlled robot arm that has high intrafraction reproducibility with repositioning of the ultrasound probe. In this study, we introduce virtual springs (VS) to assist with interfraction probe repositioning and we compare the soft tissue deformation introduced by VS to the deformation that would exist without them.Methods:Three metal markers were surgically implanted in the kidney of one dog. The dog was anesthetized and immobilized supine in an alpha cradle. The reference ultrasound probe position and force to ideally visualize the kidney was defined by an experienced ultrasonographer using the Clarity ultrasound system and robot sensor. For each interfraction study, the dog was removed from the cradle and re‐setup based on CBCT with bony anatomy alignment to mimic regular patient setup. The ultrasound probe was automatically returned to the reference position using the robot. To accommodate the soft tissue anatomy changes between each setup the operator used the VS feature to adjust the probe and obtain an ultrasound image that matched the reference image. CBCT images were acquired and each interfraction marker location was compared with the first interfractionResult. Results:Analysis of the marker positions revealed that the kidney was displaced by 18.8 ± 6.4 mm without VS and 19.9 ± 10.5 mm with VS. No statistically significant differences were found between two procedures.Conclusion:The VS feature is necessary to obtain matching ultrasound images, and they do not introduce further changes to the tissue deformation. Future work will focus on automatic VS based on ultrasound feedback.Supported in part by: NCI R01 CA161613; Elekta Sponsored Research
SU‐E‐J‐120: X‐Ray Imaging System with Scattering Reduction and Phase Contrast
Authors: Feng Y 
Published: July 2014

Purpose:To improve X‐ray quality, we proposed an optimization method and a design of imaging system that combine the capabilities of suppressing scattering and enhancing phase contrast. The images were reconstructed by combing both temporal and spatial multiplexing approaches.Methods:Numerical calculation methods were applied to obtain the angle distraction X‐Ray emerging from an object. The geometrical parameters of the imaging system was optimized to achieve high scattering suppress and high angle resolution, in order to obtain high definition imaging enhanced by phase contrast. Numerical method was used to simulate this system to image a phantom with density variations. The Expectation‐maximization algorithm was used to reconstruct images.Results:A primary design of the imaging system was accomplished. The simulation of the imaging system showed high efficiency in suppressing scattering and high sensitivity in phase contrast.Conclusion:The innovated collimation system showed promising in high definition X‐ray imaging with phase contrast.
SU‐E‐J‐122: Detecting Treatment‐Induced Metabolic Abnormalities in Craniopharyngioma Patients Undergoing Surgery and Proton Therapy
Authors: Hua C , Shulkin B , Indelicato D , Boop F , Li Y , LI X , Merchant T 
Published: July 2014

Purpose:To identify treatment‐induced defects in the brain of children with craniopharyngioma receiving surgery and proton therapy using fluorodeoxyglucose positron emission tomography (FDG PET).Methods:Forty seven patients were enrolled on a clinical trial for craniopharyngioma with serial imaging and functional evaluations. Proton therapy was delivered using the double‐scattered beams with a prescribed dose of 54 Cobalt Gray Equivalent. FDG tracer uptake in each of 63 anatomical regions was computed after warping PET images to a 3D reference template in Talairach coordinates. Regional uptake was deemed significantly low or high if exceeding two standard deviations of normal population from the mean. For establishing the normal ranges, 132 children aged 1–20 years with noncentral nervous system related diseases and normal‐appearing cerebral PET scans were analyzed. Age‐ and gender‐dependent regional uptake models were developed by linear regression and confidence intervals were calculated.Results:Most common PET abnormality before proton therapy was significantly low uptake in the frontal lobe, the occipital lobe (particularly in cuneus), the medial and ventral temporal lobe, cingulate gyrus, caudate nuclei, and thalamus. They were related to injury from surgical corridors, tumor mass effect, insertion of a ventricular catheter, and the placement of an Ommaya reservoir. Surprisingly a significantly high uptake was observed in temporal gyri and the parietal lobe. In 13 patients who already completed 18‐month PET scans, metabolic abnormalities improved in 11 patients from baseline. One patient had persistent abnormalities. Only one revealed new uptake abnormalities in thalamus, brainstem, cerebellum, and insula.Conclusion:Postoperative FDG PET of craniopharyngioma patients revealed metabolic abnormalities in specific regions of the brain. Proton therapy did not appear to exacerbate these surgery‐ and tumor‐induced defects. In patients with persistent and new abnormalities, continued investigation on clinical symptoms and cognitive outcomes is ongoing to establish the association and predictive values of metabolic imaging.
SU‐E‐J‐125: Classification of CBCT Noises in Terms of Their Contribution to Proton Range Uncertainty
Authors: Brousmiche S , Orban de Xivry J , Macq B , Seco J 
Published: July 2014

Purpose:This study assesses the potential use of CBCT images in adaptive protontherapy by estimating the contribution of the main sources of noise and calibration errors to the proton range uncertainty.Methods:Measurements intended to highlight each particular source have been achieved by adapting either the testbench configuration, e.g. use of filtration, fan‐beam collimation, beam stop arrays, phantoms and detector reset light, or the sequence of correction algorithms including water precorrection. Additional Monte‐Carlo simulations have been performed to complement these measurements, especially for the beam hardening and the scatter cases. Simulations of proton beams penetration through the resulting images have then been carried out to quantify the range change due to these effects. The particular case of a brain irradiation is considered mainly because of the multiple effects that the skull bones have on the internal soft tissues.Results:On top of the range error sources is the undercorrection of scatter. Its influence has been analyzed from a comparison of fan‐beam and full axial FOV acquisitions. In this case, large range errors of about 12 mm can be reached if the assumption is made that the scatter has only a constant contribution over the projection images. Even the detector lag, which a priori induces a much smaller effect, has been shown to contribute for up to 2 mm to the overall error if its correction only aims at reducing the skin artefact. This last result can partially be understood by the larger interface between tissues and bones inside the skull.Conclusion:This study has set the basis of a more systematical analysis of the effect CBCT noise on range uncertainties based on a combination of measurements, simulations and theoretical results. With our method, even more subtle effects such as the cone‐beam artifact or the detector lag can be assessed.SBR and JOR are financed by iMagX, a public‐private partnership between the region Wallone of Belgium and IBA under convention #1217662
SU‐E‐J‐127: Real‐Time Dosimetric Assessment for Adaptive Head‐And‐Neck Treatment Via A GPU‐Based Deformable Image Registration Framework
Authors: Qi S , Neylon J , Chen A , Low D , Kupelian P , Steinberg M , Santhanam A 
Published: July 2014

Purposes:To systematically monitor anatomic variations and their dosimetric consequences during head‐and‐neck (H' N) radiation therapy using a GPU‐based deformable image registration (DIR) framework.Methods:Eleven H' N IMRT patients comprised the subject population. The daily megavoltage CT and weekly kVCT scans were acquired for each patient. The pre‐treatment CTs were automatically registered with their corresponding planning CT through an in‐house GPU‐based DIR framework. The deformation of each contoured structure was computed to account for non‐rigid change in the patient setup. The Jacobian determinant for the PTVs and critical structures was used to quantify anatomical volume changes. Dose accumulation was performed to determine the actual delivered dose and dose accumulation. A landmark tool was developed to determine the uncertainty in the dose distribution due to registration error.Results:Dramatic interfraction anatomic changes leading to dosimetric variations were observed. During the treatment courses of 6–7 weeks, the parotid gland volumes changed up to 34.7%, the center‐of‐mass displacement of the two parotids varied in the range of 0.9–8.8mm. Mean doses were within 5% and 3% of the planned mean doses for all PTVs and CTVs, respectively. The cumulative minimum/mean/EUD doses were lower than the planned doses by 18%, 2%, and 7%, respectively for the PTV1. The ratio of the averaged cumulative cord maximum doses to the plan was 1.06±0.15. The cumulative mean doses assessed by the weekly kVCTs were significantly higher than the planned dose for the left‐parotid (p=0.03) and right‐parotid gland (p=0.006). The computation time was nearly real‐time (∼ 45 seconds) for registering each pre‐treatment CT to the planning CT and dose accumulation with registration accuracy (for kVCT) at sub‐voxel level (<1.5mm).Conclusions:Real‐time assessment of anatomic and dosimetric variations is feasible using the GPU‐based DIR framework. Clinical implementation of this technology may enable timely plan adaption and potentially lead to improved outcome.
SU‐E‐J‐128: 3D Surface Reconstruction of a Patient Using Epipolar Geometry
Authors: Kotoku J , Nakabayashi S , Haga A , Kumagai S , Ishibashi T , Arai N , Saotome N , Kobayashi T 
Published: July 2014

Purpose:To obtain a 3D surface data of a patient in a non‐invasive way can substantially reduce the effort for the registration of patient in radiation therapy. To achieve this goal, we introduced the multiple view stereo technique, which is known to be used in a “photo tourism” on the internet.Methods:70 Images were taken with a digital single‐lens reflex camera from different angles and positions. The camera positions and angles were inferred later in the reconstruction step. A sparse 3D reconstruction model was locating by SIFT features, which is robust for rotation and shift variance, in each image. We then found a set of correspondences between pairs of images by computing the fundamental matrix using the eight‐point algorithm with RANSAC. After the pair matching, we optimized the parameter including camera positions to minimize the reprojection error by use of bundle adjustment technique (non‐linear optimization). As a final step, we performed dense reconstruction and associate a color with each point using the library of PMVS.Results:Surface data were reconstructed well by visual inspection. The human skin is reconstructed well, althogh the reconstruction was time‐consuming for direct use in daily clinical practice.Conclusion:3D reconstruction using multi view stereo geometry is a promising tool for reducing the effort of patient setup.This work was supported by JSPS KAKENHI(25861128).
SU‐E‐J‐129: A Strategy to Consolidate the Image Database of a VERO Unit Into a Radiotherapy Management System
Authors: Yan Y , Medin P , Yordy J , Zhao B , Jiang S 
Published: July 2014

Purpose:To present a strategy to integrate the imaging database of a VERO unit with a treatment management system (TMS) to improve clinical workflow and consolidate image data to facilitate clinical quality control and documentation.Methods:A VERO unit is equipped with both kV and MV imaging capabilities for IGRT treatments. It has its own imaging database behind a firewall. It has been a challenge to transfer images on this unit to a TMS in a radiation therapy clinic so that registered images can be reviewed remotely with an approval or rejection record. In this study, a software system, iPump‐VERO, was developed to connect VERO and a TMS in our clinic. The patient database folder on the VERO unit was mapped to a read‐only folder on a file server outside VERO firewall. The application runs on a regular computer with the read access to the patient database folder. It finds the latest registered images and fuses them in one of six predefined patterns before sends them via DICOM connection to the TMS. The residual image registration errors will be overlaid on the fused image to facilitate image review.Results:The fused images of either registered kV planar images or CBCT images are fully DICOM compatible. A sentinel module is built to sense new registered images with negligible computing resources from the VERO ExacTrac imaging computer. It takes a few seconds to fuse registered images and send them to the TMS. The whole process is automated without any human intervention.Conclusion:Transferring images in DICOM connection is the easiest way to consolidate images of various sources in your TMS. Technically the attending does not have to go to the VERO treatment console to review image registration prior delivery. It is a useful tool for a busy clinic with a VERO unit.
SU‐E‐J‐132: Sensitivity Evaluation of Organ Based Registration for Pancreatic IGRT
Authors: Yang P , Tuli R , Sandler H , Fraass B 
Published: July 2014

Purpose:Soft‐tissue‐based CBCT registration is not always straightforward. Typical image guidance is based on use of generic registration criteria that may not be adequately sensitive to PTV and critical organ positioning errors. This work presents a novel organ‐based registration criterion to help quantify registration results and guidance.Methods:Ten pancreatic cancer patients treated using IGRT were included. Five individual CBCTs for each patient were manually registered to the planning CT by an expert. Instead of calculating the cross‐correlation (CC) for the entire imaging volume, the CC values of the PTV and critical normal tissue (limited to a 1‐cm ring around the PTV), were calculated as references. The CBCT images were then intentionally shifted in three axes by 1, 3, 5, 8, and 10 mm. New CC values were computed between the shifted CBCT and planning CT. The organ based CC was called sensitive to a given shift size when the p‐value between new and reference CC values for the 5 CBCTs was <0.05.Results:The average reference CC was 0.23 (0.06–0.41). Despite the low correlation values, the CC‐PTV is sensitive to average registration errors ≥ 5, 3 and 5 mm in the sup/inf, ant/post and right/left directions, respectively. Critical organ cross‐correlation is sensitive to registration errors ≥ 7, 4 and 6 mm in these directions. 3/10 patients showed particularly poor sensitivity (≥ 8 mm) due to low reference CC, heavy contrast presence in the planning CT or small PTV volume.Conclusion:CBCT of upper abdomen tends to have very low similarity to the planning CT, affecting registration accuracy and reliability. This organ‐based registration method focuses on the PTV and the most critical tissues, and shows improved sensitivity to positioning errors that may not be easily resolved by visual inspection.This work supported in part by grant 1R03CA173273‐01
SU‐E‐J‐133: Evaluation of Inter‐ and Intra‐Fractional Pancreas Tumor Residual Motions with Abdominal Compression
Authors: Li Y , Shi F , Tian Z , Jia X , Meyer J , Jiang S , Mao W 
Published: July 2014

Purpose:Abdominal compression (AC) has been widely used to reduce pancreas motion due to respiration for pancreatic cancer patients undergoing stereotactic body radiotherapy (SBRT). However, the inter‐fractional and intra‐fractional patient motions may degrade the treatment. The purpose of this work is to study daily CBCT projections and 4DCT to evaluate the inter‐fractional and intra‐fractional pancreatic motions.Methods:As a standard of care at our institution, 4D CT scan was performed for treatment planning. At least two CBCT scans were performed for daily treatment. Retrospective studies were performed on patients with implanted internal fiducial markers or surgical clips. The initial motion pattern was obtained by extracting marker positions on every phase of 4D CT images. Daily motions were presented by marker positions on CBCT scan projection images. An adaptive threshold segmentation algorithm was used to extract maker positions. Both marker average positions and motion ranges were compared among three sets of scans, 4D CT, positioning CBCT, and conformal CBCT, for inter‐fractional and intra‐fractional motion variations.Results:Data from four pancreatic cancer patients were analyzed. These patients had three fiducial markers implanted. All patients were treated by an Elekta Synergy with single fraction SBRT. CBCT projections were acquired by XVI. Markers were successfully detected on most of the projection images. The inter‐fractional changes were determined by 4D CT and the first CBCT while the intra‐fractional changes were determined by multiple CBCT scans. It is found that the average motion range variations are within 2 mm, however, the average marker positions may drift by 6.5 mm.Conclusion:The patients respiratory motion variation for pancreas SBRT with AC was evaluated by detecting markers from CBCT projections and 4DCT, both the inter‐fraction and intra‐fraction motion range change is small but the drift of marker positions may be comparable to motion ranges.
SU‐E‐J‐138: An IGRT QA Device for Measuring with Tenths‐Millimeter Accuracy KV and MV Isocenter Congruence, Couch Travel and Laser Alignment of Accelerators Used for SRS and SBRT
Authors: Brezovich I , Popple R , Duan J , Huang M , Benhabib S , Shen S , Cardan R , Wu X 
Published: July 2014

Purpose:To develop a practical device having sufficient accuracy for daily QA tests of accelerators used for SRS and SBRT.Methods:The UAB (Universal Alignment Ball) consists of a 6.35 mm (1/4 inch) diameter tungsten sphere located concentrically within a 25.4 mm (1 inch) diameter acrylic plastic (PMMA) sphere. The spheres are embedded in polystyrene foam, which, in turn, is surrounded by a cylindrical PMMA shell. The UAB is placed on the couch and aligned with wall lasers according to marks that have known positions in relation to the center of the spheres. Using planar and cone beam images the couch is shifted till the surface of the PMMA sphere matches Eclipse‐generated circular contours. Anterior and lateral MV images taken with small MLC openings allow measurement of distance between kV and MV isocenter, laser and MLC alignment. Measurements were taken over a one‐month period.Results:Artifacts from the tungsten sphere were confined within the PMMA sphere and did not affect cone beam localization of the sphere boundary, allowing 0.1 mm precise alignment with a computer‐generated circle centered at kV isocenter. In tests extending over a one‐month period, the distance between kV and MV isocenters along the vertical, longitudinal and lateral directions was 0.125 +/−0.06, 0.19 +/−0.08, and 0.02 +/−0.08 mm, respectively. Laser misalignment along these directions was 0.34 +/‐ 0.15, 0.74 +/−0.29, and 0.49 +/−0.22 mm. Automated couch shifts moved the spheres to within 0.1 mm of the selected position. The center of a 1cmx1cm MLC‐defined field remained within +/−0.2 mm of the tungsten sphere center as the gantry was rotated.Conclusion:The UAB is practical for daily end‐to‐end QA tests of accelerator alignment. It provides tenths‐mm accuracy for measuring agreement of kV and MV isocenters, couch motions, gantry flex and laser alignment.