bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐F‐J‐71: Improving CT Quality for Radiation Therapy Planning and Delivery Guidance Using a Non‐Linear Contrast Enhancement Technique
Authors: Noid G , Tai A , Li X 
Published: July 2016

Purpose:Advanced image post‐processing techniques which enhance soft‐tissue contrast in CT have not been widely employed for RT planning or delivery guidance. The purpose of this work is to assess the soft‐tissue contrast enhancement from non‐linear contrast enhancing filters and its impact in RT. The contrast enhancement reduces patient alignment uncertainties.Methods:Non‐linear contrast enhancing methods, such as Best Contrast (Siemens), amplify small differences in X‐ray attenuation between two adjacent structure without significantly increasing noise. Best Contrast (BC) separates a CT into two frequency bands. The low frequency band is modified by a non‐linear scaling function before recombination with the high frequency band. CT data collected using a CT‐on‐rails (Definition AS Open, Siemens) during daily CT‐guided RT for 6 prostate cancer patients and an image quality phantom (The Phantom Laboratory) were analyzed. Images acquired with a standard protocol (120 kVp, 0.6 pitch, 18 mGy CTDIvol) were processed before comparison to the unaltered images. Contrast and noise were measured in the the phantom. Inter‐observer variation was assessed by placing prostate contours on the 12 CT study sets, 6 enhanced and 6 unaltered, in a blinded study involving 8 observers.Results:The phantom data demonstrate that BC increased the contrast between the 1.0% supra‐slice element and the background substrate by 46.5 HU while noise increased by only 2.3 HU. Thus the contrast to noise ratio increased from 1.28 to 6.71. Furthermore, the variation in centroid position of the prostate contours was decreased from 1.3±0.4 mm to 0.8±0.3 mm. Thus the CTV‐to‐PTV margin was reduced by 1.1 mm. The uncertainty in delineation of the prostate/rectum edge decreased by 0.5 mm.Conclusion:As demonstrated in phantom and patient scans the BC filter accentuates soft‐tissue contrast. This enhancement leads to reduced inter‐observer variation, which should improve RT planning and delivery.Supported by Siemens
SU‐F‐J‐76: Evaluation of the Performance of Different Deformable Image Registration Algorithms in Helical, Axial and Cone‐Beam CT Images of a Mobile Phantom
Authors: Jaskowiak J , Alsbou N , Ahmad S , Ali I 
Published: July 2016

Purpose:To investigate quantitatively the performance of different deformable‐image‐registration algorithms (DIR) with helical (HCT), axial (ACT) and cone‐beam CT (CBCT) by evaluating the variations in the CT‐numbers and lengths of targets moving with controlled motion‐patterns.Methods:Four DIR‐algorithms including demons, fast‐demons, Horn‐Schunk and Locas‐Kanade from the DIRART‐software are used to register CT‐images of a mobile‐phantom. A mobile‐phantom is scanned with different imaging techniques that include helical, axial and cone‐beam CT. The phantom includes three targets with different lengths that are made from water‐equivalent material and inserted in low‐density‐foam which is moved with adjustable motion‐amplitudes and frequencies.Results:Most of the DIR‐algorithms are able to produce the lengths of the stationary‐targets, however, they do not produce the CT‐number values in CBCT. The image‐artifacts induced by motion are more regular in CBCT imaging where the mobile‐target elongation increases linearly with motion‐amplitude. In ACT and HCT, the motion‐artifacts are irregular where some mobile ‐targets are elongated or shrunk depending on the motion‐phase during imaging. The DIR‐algorithms are successful in deforming the images of the mobile‐targets to the images of the stationary‐targets producing the CT‐number values and length of the target for motion‐amplitudes < 20 mm. Similarly in ACT, all DIR‐algorithms produced the actual CT‐number and length of the stationary‐targets for motion‐amplitudes < 15 mm. As stronger motion‐artifacts are induced in HCT and ACT, DIR‐algorithms fail to produce CT‐values and shape of the stationary‐targets and fast‐demons‐algorithm has worst performance.Conclusion:Most of DIR‐algorithms produce the CT‐number values and lengths of the stationary‐targets in HCT and ACT images that has motion‐artifacts induced by small motion‐amplitudes. As motion‐amplitudes increase, the DIR‐algorithms fail to deform mobile‐target images to the stationary‐images in HCT and ACT. In CBCT, DIR‐algorithms are successful in producing length and shape of the stationary‐targets, however, they fail to produce the accurate CT‐number level.
SU‐F‐J‐81: Evaluation of Automated Deformable Registration Between Planning Computed Tomography (CT) and Daily Cone Beam CT Images Over the Course of Prostate Cancer Radiotherapy
Authors: Matney J , Hammers J , Kaidar‐Person O , Wang A , Chen R , Das S , Marks L , Mavroidis P 
Published: July 2016

Purpose:To compute daily dose delivered during radiotherapy, deformable registration needs to be relatively fast, automated, and accurate. The aim of this study was to evaluate the performance of commercial deformable registration software for deforming between two modalities: planning computed tomography (pCT) images acquired for treatment planning and cone beam (CB) CT images acquired prior to each fraction of prostate cancer radiotherapy.Methods:A workflow was designed using MIM Software™ that aligned and deformed pCT into daily CBCT images in two steps: (1) rigid shifts applied after daily CBCT imaging to align patient anatomy to the pCT and (2) normalized intensity‐based deformable registration to account for interfractional anatomical variations. The physician‐approved CTV and organ and risk (OAR) contours were deformed from the pCT to daily CBCT over the course of treatment. The same structures were delineated on each daily CBCT by a radiation oncologist. Dice similarity coefficient (DSC) mean and standard deviations were calculated to quantify the deformable registration quality for prostate, bladder, rectum and femoral heads.Results:To date, contour comparisons have been analyzed for 31 daily fractions of 2 of 10 of the cohort. Interim analysis shows that right and left femoral head contours demonstrate the highest agreement (DSC: 0.96±0.02) with physician contours. Additionally, deformed bladder (DSC: 0.81±0.09) and prostate (DSC: 0.80±0.07) have good agreement with physician‐defined daily contours. Rectum contours have the highest variations (DSC: 0.66±0.10) between the deformed and physician‐defined contours on daily CBCT imaging.Conclusion:For structures with relatively high contrast boundaries on CBCT, the MIM automated deformable registration provided accurate representations of the daily contours during treatment delivery. These findings will permit subsequent investigations to automate daily dose computation from CBCT. However, improved methods need to be investigated to improve deformable results for rectum contours.
SU‐F‐J‐84: Comparison of Quantitative Deformable Image Registration Evaluation Tools: Application to Prostate IGART
Authors: Dogan N , Weiss E , Sleeman W , Christensen G , Williamson J , Ford J 
Published: July 2016

Purpose:Errors in displacement vector fields (DVFs) generated by Deformable Image Registration (DIR) algorithms can give rise to significant uncertainties in contour propagation and dose accumulation in Image‐Guided Adaptive Radiotherapy (IGART). The purpose of this work is to assess the accuracy of two DIR algorithms using a variety of quality metrics for prostate IGART.Methods:Pelvic CT images were selected from an anonymized database of nineteen prostate patients who underwent 8–12 serial scans during radiotherapy. Prostate, bladder, and rectum were contoured on 34 image‐sets for three patients by the same physician. The planning CT was deformably‐registered to daily CT using three variants of the Small deformation Inverse Consistent Linear Elastic (SICLE) algorithm: Grayscale‐driven (G), Contour‐driven (C, which utilizes segmented structures to drive DIR), combined (G+C); and also grayscale ITK demons (Gd). The accuracy of G, C, G+C SICLE and Gd registrations were evaluated using a new metric Edge Gradient Distance to Agreement (EGDTA) and other commonly‐used metrics such as Pearson Correlation Coefficient (PCC), Dice Similarity Index (DSI) and Hausdorff Distance (HD).Results:C and G+C demonstrated much better performance at organ boundaries, revealing the lowest HD and highest DSI, in prostate, bladder and rectum. G+C demonstrated the lowest mean EGDTA (1.14 mm), which corresponds to highest registration quality, compared to G and C DVFs (1.16 and 2.34 mm). However, demons DIR showed the best overall performance, revealing lowest EGDTA (0.73 mm) and highest PCC (0.85).Conclusion:As expected, both C‐ and C+G SICLE more accurately reproduce manually‐contoured target datasets than G‐SICLE or Gd using HD and DSI metrics. In general, the Gd appears to have difficulty reproducing large daily position and shape changes in the rectum and bladder. However, Gd outperforms SICLE in terms of EGDTA and PCC metrics, possibly at the expense of topological quality of the estimated DVFs.
SU‐F‐J‐85: Evaluation of the Velocity Deformable Image Registration Algorithm
Authors: Polan D , Kamp J , Lee JY , Chapman C , Green M , Payal S , Kessler M , Brock K 
Published: July 2016

Purpose:To perform validation and commissioning of a commercial deformable image registration (DIR) algorithm (Velocity, Varian Medical Systems) for numerous clinical sites using single and multi‐modality images.Methods:In this retrospective study, the DIR algorithm was evaluated for 10 patients in each of the following body sites: head and neck (HN), prostate, liver, and gynecological (GYN). HN DIRs were evaluated from planning (p)CT to re‐pCT and pCTs to daily CBCTs using dice similarity coefficients (DSC) of corresponding anatomical structures. Prostate DIRs were evaluated from pCT to CBCTs using DSC and target registration error (TRE) of implanted RF beacons within the prostate. Liver DIRs were evaluated from pMR to pCT using DSC and TRE of vessel bifurcations. GYN DIRs were evaluated between fractionated brachytherapy MRIs using DSC of corresponding anatomical structures.Results:Analysis to date has given average DSCs for HN pCT‐to‐(re)pCT DIR for the brainstem, cochleas, constrictors, spinal canal, cord, esophagus, larynx, parotids, and submandibular glands as 0.88, 0.65, 0.67, 0.91, 0.77, 0.69, 0.77, 0.87, and 0.71, respectively. Average DSCs for HN pCT‐to‐CBCT DIR for the constrictors, spinal canal, esophagus, larynx, parotids, and submandibular glands were 0.64, 0.90, 0.62, 0.82, 0.75, and 0.69, respectively. For prostate pCT‐to‐CBCT DIR the DSC for the bladder, femoral heads, prostate, and rectum were 0.71, 0.82, 0.69, and 0.61, respectively. Average TRE using implanted beacons was 3.35 mm. For liver pCT‐to‐pMR, the average liver DSC was 0.94 and TRE was 5.26 mm. For GYN MR‐to‐MR DIR the DSC for the bladder, sigmoid colon, GTV, and rectum were 0.79, 0.58, 0.67, and 0.76, respectively.Conclusion:The Velocity DIR algorithm has been evaluated over a number of anatomical sites. This work functions to document the uncertainties in the DIR in the commissioning process so that these can be accounted for in the development of downstream clinical processes.This work was supported in part by a co‐development agreement with Varian Medical Systems
SU‐F‐J‐87: Impact Of The Dosimetric Consequences From Minimal Displacements Throughout The Treatment Time In APBI With SAVI Applicators
Authors: Chandrasekara S , Pella S , Hyvarinen M , Pinder J 
Published: July 2016

Purpose:To assess the variation in dose received by the organs at risk (OARs) due to inter‐fractional motion by SAVI to determine the importance of providing proper immobilizationMethods:An analysis of 15 patients treated with SAVI applicators were considered for this study. Treatment planning teams did not see significant changes in their CT scans through scout images and initial treatment plan was used for the entire treatment. These scans, taken before each treatment were imported in to the treatment planning system and were fused together with respective to the applicator, using landmark registration. Dosimetric evaluations were performed. Dose received by skin, ribs and PTV(Planning target volume) respect to the initial treatment plan were measured.Results:Contours of the OARs were not similar with the initial image. Deduction in volumes of PTV and cavity, small deviations in displacements from the applicator to the OARs, difference in doses received by the OARs between treatments were noticed. The maximum, minimum, average doses varied between 10% to 20% 5% to 8% and 15% to 20% in ribs and skin. The 0.1cc doses to OARs showed an average change of 10% of the prescribed dose. PTV was receiving a different dose than the estimated doseConclusion:The variation in volumes and isodoses related to the OARs, PTV receiving a lesser dose than the prescribed dose indicate that the estimated doses are different from the received dose. This study reveals the urgent need of improving the immobilization methods. Taking a CT scan before each treatment and replanning is helpful to minimize the risk of delivering undesired high doses to the OARs. Patient positioning, motion, respiration, observer differences and time lap between the planning and treating can arise more complications. VacLock, Positioning cushions, Image guided brachytherapy and adjustable registration should be used for further improvements.
SU‐F‐J‐95: Impact of Shape Complexity On the Accuracy of Gradient‐Based PET Volume Delineation
Authors: Dance M , Wu G , Gao Y , Pirozzi S , Nelson A , Das S , Lian J 
Published: July 2016

Purpose:Explore correlation of tumor complexity shape with PET target volume accuracy when delineated with gradient‐based segmentation tool.Methods:A total of 24 clinically realistic digital PET Monte Carlo (MC) phantoms of NSCLC were used in the study. The phantom simulated 29 thoracic lesions (lung primary and mediastinal lymph nodes) of varying size, shape, location, and 18F‐FDG activity. A program was developed to calculate a curvature vector along the outline and the standard deviation of this vector was used as a metric to quantify a shape's “complexity score”. This complexity score was calculated for standard geometric shapes and MC‐generated target volumes in PET phantom images. All lesions were contoured using a commercially available gradient‐based segmentation tool and the differences in volume from the MC‐generated volumes were calculated as the measure of the accuracy of segmentation.Results:The average absolute percent difference in volumes between the MC‐volumes and gradient‐based volumes was 11% (0.4%–48.4%). The complexity score showed strong correlation with standard geometric shapes. However, no relationship was found between the complexity score and the accuracy of segmentation by gradient‐based tool on MC simulated tumors (R2 = 0.156). When the lesions were grouped into primary lung lesions and mediastinal/mediastinal adjacent lesions, the average absolute percent difference in volumes were 6% and 29%, respectively. The former group is more isolated and the latter is more surround by tissues with relatively high SUV background.Conclusion:The complexity shape of NSCLC lesions has little effect on the accuracy of the gradient‐based segmentation method and thus is not a good predictor of uncertainty in target volume delineation. Location of lesion within a relatively high SUV background may play a more significant role in the accuracy of gradient‐based segmentation.
SU‐F‐J‐98: Improvement and Evaluation Of Deformation Image Registration On Parotid Glands During Radiation Therapy for Nasopharyngeal Cancer
Authors: Xu S , Wu Z , Liu B , Li Y , Gong H , Zhou F , Qu B , Liu Y 
Published: July 2016

Purpose:To quantitatively evaluate the strategic innovation and accuracy variation of deformation registration algorithm for parotid glands using the similarity Dice coefficient during the course of radiation therapy (RT) for nasopharyngeal cancer (NPC).Methods:Daily MVCT data for 10 patients with pathologically proven nasopharyngeal cancers were analyzed. The data were acquired using tomotherapy (TomoTherapy, Accuray) at the PLA General Hospital. The prescription dose to the primary target was 70Gy in 33 fractions. Two kinds of contours for parotid glands on daily MVCTs were obtained by populating these contours from planning CTs to the daily CTs via rigid‐body registration with or without the rotation shifts using the in‐house tools and the Adaptive plan software (Adaptive Plan, TomoTherapy), and were edited manually if necessary. The diffeomorphic Demons algorithm developed in the in‐house tool was used to propagate the parotid structures from the daily CTs to planning CTs. The differences of the mapped parotid contours in two methods were evaluated using Dice similarity index (DSI). Two‐tailed t‐test analysis was carried out to compare the DSI changes during the course of RT.Results:For 10 patient plans, the accuracy of deformation image registration (DIR) with the rotation shift was obviously better than those without the rotation shift. The Dice scores of the ipsi‐ and contra‐lateral parotids for with and without the rotation shifts were found to be correlated with each other [0.904±0.031 vs 0.919±0.030 (p<0.001); 0.900±0.031 vs 0.910±0.032 (p<0.001)]. The Dice scores for the parotids have shown the reduction with the changes of parotid volumes during RT. The DSI values between the first and last fraction were 0.932±0.020 vs 0.899±0.030 in 10 patient plans.Conclusion:DIR was successfully improved using the strategic innovation for ART. And the decrease of DIR accuracy has also been found during the delivery of fractionated radiotherapy.This work was supported in part by the grant from Chinese Natural Science Foundation (Grant No. 11105225).
SU‐F‐J‐100: Standardized Biodistribution Template for Nuclear Medicine Dosimetry Collection and Reporting
Authors: Kesner A , Poli G , Beykan S , Lassman M 
Published: July 2016

Purpose:As the field of Nuclear Medicine moves forward with efforts to integrate radiation dosimetry into clinical practice we can identify the challenge posed by the lack of standardized dose calculation methods and protocols. All personalized internal dosimetry is derived by projecting biodistribution measurements into dosimetry calculations. In an effort to standardize organization of data and its reporting, we have developed, as a sequel to the EANM recommendation of “Good Dosimetry Reporting”, a freely available biodistribution template, which can be used to create a common point of reference for dosimetry data. It can be disseminated, interpreted, and used for method development widely across the field.Methods:A generalized biodistribution template was built in a comma delineated format (.csv) to be completed by users performing biodistribution measurements. The template is available for free download. The download site includes instructions and other usage details on the template.Results:This is a new resource developed for the community. It is our hope that users will consider integrating it into their dosimetry operations. Having biodistribution data available and easily accessible for all patients processed is a strategy for organizing large amounts of information. It may enable users to create their own databases that can be analyzed for multiple aspects of dosimetry operations. Furthermore, it enables population data to easily be reprocessed using different dosimetry methodologies. With respect to dosimetry‐related research and publications, the biodistribution template can be included as supplementary material, and will allow others in the community to better compare calculations and results achieved.Conclusion:As dosimetry in nuclear medicine become more routinely applied in clinical applications, we, as a field, need to develop the infrastructure for handling large amounts of data. Our organ level biodistribution template can be used as a standard format for data collection, organization, as well as for dosimetry research and software development.
SU‐F‐J‐105: Towards a Novel Treatment Planning Pipeline Delivering Pareto‐ Optimal Plans While Enabling Inter‐ and Intrafraction Plan Adaptation
Authors: Kontaxis C , Breedveld S , Bol G , Sharfo A , Heijmen B , Lagendijk J , Raaymakers B 
Published: July 2016

Purpose:To develop a new IMRT treatment planning methodology suitable for the new generation of MR‐linear accelerator machines. The pipeline is able to deliver Pareto‐optimal plans and can be utilized for conventional treatments as well as for inter‐ and intrafraction plan adaptation based on real‐time MR‐data.Methods:A Pareto‐optimal plan is generated using the automated multicriterial optimization approach Erasmus‐iCycle. The resulting dose distribution is used as input to the second part of the pipeline, an iterative process which generates deliverable segments that target the latest anatomical state and gradually converges to the prescribed dose. This process continues until a certain percentage of the dose has been delivered. Under a conventional treatment, a Segment Weight Optimization (SWO) is then performed to ensure convergence to the prescribed dose. In the case of inter‐ and intrafraction adaptation, post‐processing steps like SWO cannot be employed due to the changing anatomy. This is instead addressed by transferring the missing/excess dose to the input of the subsequent fraction. In this work, the resulting plans were delivered on a Delta4 phantom as a final Quality Assurance test.Results:A conventional static SWO IMRT plan was generated for two prostate cases. The sequencer faithfully reproduced the input dose for all volumes of interest. For the two cases the mean relative dose difference of the PTV between the ideal input and sequenced dose was 0.1% and −0.02% respectively. Both plans were delivered on a Delta4 phantom and passed the clinical Quality Assurance procedures by achieving 100% pass rate at a 3%/3mm gamma analysis.Conclusion:We have developed a new sequencing methodology capable of online plan adaptation. In this work, we extended the pipeline to support Pareto‐optimal input and clinically validated that it can accurately achieve these ideal distributions, while its flexible design enables inter‐ and intrafraction plan adaptation.This research is financially supported by Elekta AB, Stockholm, Sweden.