bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐E‐J‐92: On‐Line Cone Beam CT Based Planning for Emergency and Palliative Radiation Therapy
Authors: Held M , Morin O , Pouliot J 
Published: July 2014

Purpose:To evaluate and develop the feasibility of on‐line cone beam CT based planning for emergency and palliative radiotherapy treatments.Methods:Subsequent to phantom studies, a case library of 28 clinical megavoltage cone beam CT (MVCBCT) was built to assess dose‐planning accuracies on MVCBCT for all anatomical sites. A simple emergency treatment plan was created on the MVCBCT and copied to its reference CT. The agreement between the dose distributions of each image pair was evaluated by the mean dose difference of the dose volume and the gamma index of the central 2D axial plane. An array of popular urgent and palliative cases was also evaluated for imaging component clearance and field‐of‐view.Results:The treatment cases were categorized into four groups (head and neck, thorax/spine, pelvis and extremities). Dose distributions for head and neck treatments were predicted accurately in all cases with a gamma index of >95% for 2% and 2 mm criteria. Thoracic spine treatments had a gamma index as low as 60% indicating a need for better uniformity correction and tissue density calibration. Small anatomy changes between CT and MVCBCT could contribute to local errors. Pelvis and sacral spine treatment cases had a gamma index between 90% and 98% for 3%/3 mm criteria. The limited FOV became an issue for large pelvis patients. Imaging clearance was difficult for cases where the tumor was positioned far off midline.Conclusion:The MVCBCT based dose planning and delivery approach is feasible in many treatment cases. Dose distributions for head and neck patients are unrestrictedly predictable. Some FOV restrictions apply to other treatment sites. Lung tissue is most challenging for accurate dose calculations given the current imaging filters and corrections. Additional clinical cases for extremities need to be included in the study to assess the full range of site‐specific planning accuracies.This work is supported by Siemens.
SU‐E‐J‐102: Separation of Metabolic Supply and Demand: From Power Grid Economics to Cancer Metabolism
Authors: Epstein T , Xu L , Gillies R , Gatenby R 
Published: July 2014

Purpose:To study a new model of glucose metabolism which is primarily governed by the timescale of the energetic demand and not by the oxygen level, and its implication on cancer metabolism (Warburg effect)Methods:1) Metabolic profiling of membrane transporters activity in several cell lines, which represent the spectrum from normal breast epithelium to aggressive, metastatic cancer, using Seahorse XF reader.2) Spatial localization of oxidative and non‐oxidative metabolic components using immunocytochemical imaging of the glycolytic ATP‐producing enzyme, pyruvate kinase and mitochondria. 3) Finite element simulations of coupled partial differential equations using COMSOL and MATLAB.Results:Inhibition or activation of pumps on the cell membrane led to reduction or increase in aerobic glycolysis, respectively, while oxidative phosphorylation remained unchanged. These results were consistent with computational simulations of changes in short‐timescale demand for energy by cell membrane processes. A specific model prediction was that the spatial distribution of ATP‐producing enzymes in the glycolytic pathway must be primarily localized adjacent to the cell membrane, while mitochondria should be predominantly peri‐nuclear. These predictions were confirmed experimentally.Conclusion:The results in this work support a new model for glucose metabolism in which glycolysis and oxidative phosphorylation supply different types of energy demand. Similar to power grid economics, optimal metabolic control requires the two pathways, even in normoxic conditions, to match two different types of energy demands. Cells use aerobic metabolism to meet baseline, steady energy demand and glycolytic metabolism to meet short‐timescale energy demands, mainly from membrane transport activities, even in the presence of oxygen. This model provides a mechanism for the origin of the Warburg effect in cancer cells. Here, the Warburg effect emerges during carcinogenesis is a physiological response to an increase in energy demands from membrane transporters, required for cell division, growth, and migration.This work is supported by the NIH Physical Sciences in Oncology Center grant 1U54CA143970‐03 and NIH R01 CA077575‐10.
SU‐E‐J‐103: Setup Errors Analysis by Cone‐Beam CT (CBCT)‐Based Imaged‐Guided Intensity Modulated Radiotherapy for Esophageal Cancer
Authors: Yang H , Wang W , Hu W , Chen X , Wang X , Yu C 
Published: July 2014

Purpose:To quantify setup errors by pretreatment kilovolt cone‐beam computed tomography(KV‐CBCT) scans for middle or distal esophageal carcinoma patients.Methods:Fifty‐two consecutive middle or distal esophageal carcinoma patients who underwent IMRT were included this study. A planning CT scan using a big‐bore CT simulator was performed in the treatment position and was used as the reference scan for image registration with CBCT. CBCT scans(On‐Board Imaging v1. 5 system, Varian Medical Systems) were acquired daily during the first treatment week. A total of 260 CBCT scans was assessed with a registration clip box defined around the PTV‐thorax in the reference scan based on(nine CBCTs per patient) bony anatomy using Offline Review software v10.0(Varian Medical Systems). The anterior‐posterior(AP), left‐right(LR), superiorinferior(SI) corrections were recorded. The systematic and random errors were calculated. The CTV‐to‐PTV margins in each CBCT frequency was based on the Van Herk formula (2.5Σ+0.7σ).Results:The SD of systematic error (Σ) was 2.0mm, 2.3mm, 3.8mm in the AP, LR and SI directions, respectively. The average random error (σ) was 1.6mm, 2.4mm, 4.1mm in the AP, LR and SI directions, respectively. The CTV‐to‐PTV safety margin was 6.1mm, 7.5mm, 12.3mm in the AP, LR and SI directions based on van Herk formula.Conclusion:Our data recommend the use of 6 mm, 8mm, and 12 mm for esophageal carcinoma patient setup in AP, LR, SI directions, respectively.
SU‐E‐J‐105: Stromal‐Epithelial Responses to Fractionated Radiotherapy
Authors: Qayyum M 
Published: July 2014

Purpose:The stromal‐epithelial‐cell interactions that are responsible for directing normal breast‐tissue development and maintenance play a central role in the progression of breast cancer. In the present study, we developed three‐dimensional (3‐D) cell co‐cultures used to study cancerous mammary cell responses to fractionated radiotherapy. In particular, we focused on the role of the reactive stroma in determining the therapeutic ratio for postsurgical treatment.Methods:Cancerous human mammary epithelial cells were cultured in a 3‐D collagen matrix with human fibroblasts stimulated by various concentrations of transforming growth factor beta 1 (TGF‐β1). These culture samples were designed to model the post‐lumpectomy mammary stroma in the presence of residual cancer cells. We tracked over time the changes in medium stiffness, fibroblast‐cell activation (conversion to cancer activated fibroblasts (CAF)), and proliferation of both cell types under a variety of fractionated radiotherapy protocols. Samples were exposed to 6 MV X‐rays from a linear accelerator in daily fraction sizes of 90, 180 and 360 cGy over five days in a manner consistent with irradiation exposure during radiotherapy.Results:We found in fractionation studies with fibroblasts and CAF that higher doses per fraction may be more effective early on in deactivating cancer‐harboring cellular environments. Higher‐dose fraction schemes inhibit contractility in CAF and prevent differentiation of fibroblasts, thereby metabolically uncoupling tumor cells from their surrounding stroma. Yet, over a longer time period, the higher dose fractions may slow wound healing and increase ECM stiffening that could stimulate proliferation of surviving cancer cells.Conclusion:The findings suggest that dose escalation to the region with residual disease can deactivate the reactive stroma, thus minimizing the cancer promoting features of the cellular environment. Large‐fraction irradiation may be used to sterilize residual tumor cells and inhibit activation of intracellular transduction pathways that are promoted during the post‐surgical woundhealing period.NIH award R01CA138882
SU‐E‐J‐106: Study of Variation of Internal Taget Volume Between 4DCT and Slow‐CT in Respiratory Patterns Using Respiratory Motion Phantom
Authors: Lee S , Choi S , Min C , Ji Y , Jung H , Kim M , Yoo H , Kim C , Yi C , kim K 
Published: July 2014

Purpose:The objective of this study is to investigate the difference of ITV lengths and ITVs between 4DCT and Slow‐CT images according to respiratory patterns using a respiratory motion phantom.Methods:The respiratory periods 1∼4s and target motion 1∼3 cm were applied on each respiratory pattern. 4DCT and Slow‐CT images were acquired for 3 times. 4DCT and Slow‐CT ITVs were measured with contouring the target in the Eclipse RTP system. The measured ITV lenghts and ITVs in 4DCT and Slow‐CT images were compared to the known values.Results:For the ITV lengths and ITVs in the 4DCT, the difference of them were reduced as the respiratory period is longer and target motion is shorter. For the Slow‐CT, there was same tendency with change in 4DCT ITV lengths and ITVs about target motion. According to the respiratory patterns, pattern A had the highest reproducibility. Pattern B, C and D were showed the difference similar to each other. However, for pattern E, the reproducibility was the lowest compared with other four patterns. The difference of ITV lengths and ITVs between Slow‐CT and 4DCT was increased by increasing the respiratory periods and target motion for all respiratory patterns. In case of pattern A, B and C, length difference was 3 mm at S(superior) and I(inferior) direction, and the length difference of pattern D was 1.45 cm at only “I” direction whereas the length difference of pattern E was 5 mm longer in “S” direction than “I” direction.Conclusion:The margin in SI directions should be determined by considering the respiratory patterns when the margin of Slow‐CT is compensated for 4DCT ITV lengths. Afterward, we think that the Resultof this study will be useful to analyze the ITV lengths and ITVs from the CT images on the basis of the patient respiratory signals.
SU‐E‐J‐135: An Investigation of Ultrasound Imaging for 3D Intra‐Fraction Prostate Motion Estimation
Authors: O' Shea T , Harris E , Evans P , Bamber J 
Published: July 2014

Purpose:This study investigates the use of a mechanically swept 3D ultrasound (US) probe to estimate intra‐fraction motion of the prostate during radiation therapy using an US phantom and simulated transperineal imaging.Methods:A 3D motion platform was used to translate an US speckle phantom while simulating transperineal US imaging. Motion patterns for five representative types of prostate motion, generated from patient data previously acquired with a Calypso system, were using to move the phantom in 3D. The phantom was also implanted with fiducial markers and subsequently tracked using the CyberKnife kV x‐ray system for comparison. A normalised cross correlation block matching algorithm was used to track speckle patterns in 3D and 2D US data. Motion estimation results were compared with known phantom translations.Results:Transperineal 3D US could track superior‐inferior (axial) and anterior‐posterior (lateral) motion to better than 0.8 mm root‐mean‐square error (RMSE) at a volume rate of 1.7 Hz (comparable with kV x‐ray tracking RMSE). Motion estimation accuracy was poorest along the US probe's swept axis (right‐left; RL; RMSE < 4.2 mm) but simple regularisation methods could be used to improve RMSE (< 2 mm). 2D US was found to be feasible for slowly varying motion (RMSE < 0.5 mm). 3D US could also allow accurate radiation beam gating with displacement thresholds of 2 mm and 5 mm exhibiting a RMSE of less than 0.5 mm.Conclusion:2D and 3D US speckle tracking is feasible for prostate motion estimation during radiation delivery. Since RL prostate motion is small in magnitude and frequency, 2D or a hybrid (2D/3D) US imaging approach which also accounts for potential prostate rotations could be used. Regularisation methods could be used to ensure the accuracy of tracking data, making US a feasible approach for gating or tracking in standard or hypo‐fractionated prostate treatments.
SU‐E‐J‐136: Multimodality‐Image‐Based Target Delineation for Dose Painting of Pancreatic Cancer
Authors: Dalah E , Paulson E , Erickson B , Li X 
Published: July 2014

Purpose:Dose escalated RT may provide improved disease local‐control for selected unresectable pancreatic cancer. Accurate delineation of the gross tumor volume (GTV) inside pancreatic head or body would allow safe dose escalation considering the tolerances of adjacent organs at risk (OAR). Here we explore the potential of multi‐modality imaging (DCE‐MRI, ADC‐MRI, and FDG‐PET) to define the GTV for dose painting of pancreatic cancer. Volumetric variations of DCE‐MRI, ADC‐MRI and FDG‐PET defined GTVs were assessed in comparison to the findings on CT, and to pathology specimens for resectable and borderline reseactable cases of pancreatic cancer.Methods:A total of 19 representative patients with DCE‐MRI, ADC‐MRI and FDG‐PET data were analyzed. Of these, 8 patients had pathological specimens. GTV, inside pancreatic head/neck, or body, were delineated on MRI (denoted GTVDCE, and GTVADC), on FDG‐PET using SUV of 2.5, 40% SUVmax, and 50% SUVmax (denoted GTV2.5, GTV40%, and GTV50%). A Kruskal‐Wallis test was used to determine whether significant differences existed between GTV volumes.Results:Significant statistical differences were found between the GTVs defined by DCE‐MRI, ADC‐MRI, and FDG‐PET, with a mean and range of 4.73 (1.00–9.79), 14.52 (3.21–25.49), 22.04 (1.00–45.69), 19.10 (4.84–45.59), and 9.80 (0.32–35.21) cm3 (p<0.0001) for GTVDCE, GTVADC, GTV2.5, GTV40%, and GTV50%, respectively. The mean difference and range in the measurements of maximum dimension of GTVs based on DCE‐MRI, ADC‐MRI, SUV2.5, 40% SUVmax, and 50% SUVmax compared with pathologic specimens were −0.84 (−2.24 to 0.9), 0.41 (−0.15 to 2.3), 0.58 (−1.41 to 3.69), 0.66 (−0.67 to 1.32), and 0.15 (−1.53 to 2.38) cm, respectively.Conclusion:Differences exists between DCE, ADC, and PET defined target volumes for RT of pancreatic cancer. Further studies combined with pathological specimens are required to identify the optimal imaging modality and/or acquisition method to define the GTV.
SU‐E‐J‐137: Incorporating Tumor Regression Into Robust Plan Optimization for Head and Neck Radiotherapy
Authors: Zhang P , Hu J , Tyagi N , Mageras G , Lee N , Hunt M 
Published: July 2014

Purpose:To develop a robust planning paradigm which incorporates a tumor regression model into the optimization process to ensure tumor coverage in head and neck radiotherapy.Methods:Simulation and weekly MR images were acquired for a group of head and neck patients to characterize tumor regression during radiotherapy. For each patient, the tumor and parotid glands were segmented on the MR images and the weekly changes were formulated with an affine transformation, where morphological shrinkage and positional changes are modeled by a scaling factor, and centroid shifts, respectively. The tumor and parotid contours were also transferred to the planning CT via rigid registration. To perform the robust planning, weekly predicted PTV and parotid structures were created by transforming the corresponding simulation structures according to the weekly affine transformation matrix averaged over patients other than him/herself. Next, robust PTV and parotid structures were generated as the union of the simulation and weekly prediction contours. In the subsequent robust optimization process, attainment of the clinical dose objectives was required for the robust PTV and parotids, as well as other organs at risk (OAR). The resulting robust plans were evaluated by looking at the weekly and total accumulated dose to the actual weekly PTV and parotid structures. The robust plan was compared with the original plan based on the planning CT to determine its potential clinical benefit.Results:For four patients, the average weekly change to tumor volume and position was −4% and 1.2 mm laterally‐posteriorly. Due to these temporal changes, the robust plans resulted in an accumulated PTV D95 that was, on average, 2.7 Gy higher than the plan created from the planning CT. OAR doses were similar.Conclusion:Integration of a tumor regression model into target delineation and plan robust optimization is feasible and may yield improved tumor coverage.Part of this research is supported by Varian Medical System
SU‐E‐J‐141: Comparison of Dose Calculation On Automatically Generated MRBased ED Maps and Corresponding Patient CT for Clinical Prostate EBRT Plans
Authors: Schadewaldt N , Schulz H , Helle M , Frantzen‐Steneker M , Heide U , Renisch S 
Published: July 2014

Purpose:To analyze the effect of computing radiation dose on automatically generated MR‐based simulated CT images compared to true patient CTs.Methods:Six prostate cancer patients received a regular planning CT for RT planning as well as a conventional 3D fast‐field dual‐echo scan on a Philips 3.0T Achieva, adding approximately 2 min of scan time to the clinical protocol. Simulated CTs (simCT) where synthesized by assigning known average CT values to the tissue classes air, water, fat, cortical and cancellous bone. For this, Dixon reconstruction of the nearly out‐of‐phase (echo 1) and in‐phase images (echo 2) allowed for water and fat classification. Model based bone segmentation was performed on a combination of the DIXON images. A subsequent automatic threshold divides into cortical and cancellous bone. For validation, the simCT was registered to the true CT and clinical treatment plans were re‐computed on the simCT in pinnacle3. To differentiate effects related to the 5 tissue classes and changes in the patient anatomy not compensated by rigid registration, we also calculate the dose on a stratified CT, where HU values are sorted in to the same 5 tissue classes as the simCT.Results:Dose and volume parameters on PTV and risk organs as used for the clinical approval were compared. All deviations are below 1.1%, except the anal sphincter mean dose, which is at most 2.2%, but well below clinical acceptance threshold. Average deviations are below 0.4% for PTV and risk organs and 1.3% for the anal sphincter. The deviations of the stratifiedCT are in the same range as for the simCT. All plans would have passed clinical acceptance thresholds on the simulated CT images.Conclusion:This study demonstrated the clinical usability of MR based dose calculation with the presented Dixon acquisition and subsequent fully automatic image processing.N. Schadewaldt, H. Schulz, M. Helle and S. Renisch are employed by Phlips Technologie Innovative Techonologies, a subsidiary of Royal Philips NV.
SU‐E‐J‐143: Short‐ and Near‐Term Effects of Proton Therapy On Cerebral White Matter
Authors: Uh J , Merchant T , Ogg R , Sabin N , Indelicato D , Hua C 
Published: July 2014

Purpose:To assess early effects of proton therapy on the structural integrity of cerebral white matter in relation to the subsequent near‐term development of such effects.Methods:Sixteen children (aged 2–19 years) with craniopharyngioma underwent proton therapy of 54 Cobalt Gray Equivalent (CGE) in a prospective therapeutic trial. Diffusion tensor imaging (DTI) was performed at baseline before proton therapy and every 3 months thereafter. Tract‐based spatial statics analysis of DTI data was performed to derive the fractional anisotropy (FA) and radial diffusivity (RD) in 26 volumes of interest (VOIs). The dose distributions were spatially normalized to identify VOIs prone to high doses. The longitudinal percentage changes of the FA and RD in these VOIs at 3 and 12 months from the baseline were calculated, and their relationships were evaluated.Results:The average dose was highest to the cerebral peduncle (CP), corticospinal tract (CST) in the pons, pontine crossing tract (PCT), anterior/posterior limbs of the internal capsule (ALIC/PLIC), and genu of the corpus callosum (GCC). It ranged from 33.3 GCE (GCC) to 49.7 GCE (CP). A mild but statistically significant (P<0.05) decline of FA was observed 3 months after proton therapy in all VOIs except the PLIC and ranged from −1.7% (ALIC) to −2.8% (PCT). A significant increase of RD was found in the CP (3.5%) and ALIC (2.1%). The average longitudinal change from the baseline was reduced at 12 months for most VOIs. However, the standard deviation increased, indicating that the temporal pattern varied individually. The follow‐up measurements at 3 and 12 months correlated for the CP, CST, PCT, and GCC (P < 0.04).Conclusion:DTI data suggest early (3 months) effects of proton therapy on microstructures in the white matter. The subsequent follow‐up indicated individual variation of the changes, which was partly implied by the early effects.
SU‐E‐J‐144: MRI Visualization of a Metallic Fiducial Marker Used for Image Guided Prostate Radiotherapy
Authors: Yee S , Krauss D , Yan D 
Published: July 2014

Purpose:Unlike on the daily CBCT used for the image‐guided radiation therapy, the visualization of an implantable metallic fiducial marker on the planning MRI images has been a challenge due to the inherent insensitivity of metal in MRI, and very thin (∼ 1 mm or less) diameter. Here, an MRI technique to visualize a marker used for prostate cancer radiotherapy is reported.Methods:During the MRI acquisitions, a multi‐shot turbo spin echo (TSE) technique (TR=3500 ms, TE=8.6 ms, ETL=17, recon voxel=0.42×0.42×3.5 mm3) was acquired in Philips 3T Ingenia together with a T2‐weighted multi‐shot TSE (TR=5381 ms, TE=110 ms, ETL=17, recon voxel=0.47×0.47×3 mm3) and a balanced turbo field echo (bTFE, flip angle 60, TR=2.76 ms, TE=1.3 ms, 0.85×0.85×3 mm3, NSA=4). In acquiring the MRI to visualize the fiducial marker, a particular emphasis was made to improve the spatial resolution and visibility in the generally dark, inhomogeneous prostate area by adjusting the slice profile ordering and TE values of TSE acquisition (in general, the lower value of TE in TSE acquisition generates a brighter signal but at the cost of high spatial resolution since the k‐space, responsible for high spatial resolution, is filled with noisier data).Results:While clearly visible in CT, the marker was not visible in either T2‐weighted TSE or bTFE, although the image qualities of both images were superior. In the new TSE acquisition (∼ a proton‐density weighted image) adjusted by changing the profile ordering and the TE value, the marker was visible as a negative (but clear) contrast in the magnitude MRI, and as a positive contrast in the imaginary image of the phase‐sensitive MRI.Conclusion:A metallic fiducial marker used for image guidance before prostate cancer radiotherapy can be made visible in MRI, which may facilitate more use of MRI in planning and guiding such radiation therapy.