bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐E‐J‐25: Analysis of Commercial 4DCT Flaws and the Potential Benefits of a New Technique for Irregular Breathing Patients
Authors: Dou T , Thomas D , Lamb J , Low D 
Published: July 2014

Purpose:To determine the distribution of inhalation to exhalation breathing amplitudes as measured using a commercial 4DCT and a proposed 4DCT protocol for irregular breathing patients.Methods:External breathing surrogate signals correlating with lung tidal volume were collected using an abdominal bellows for a set of 50 patients. Breathing traces over 5‐minute durations were evaluated and the peak inhalation and exhalation peaks identified. An arbitrary time point was identified and the nearest exhalation peak located within a ±180° gantry rotation period. The times at which the follow‐up inhalation scans occurred were correlated with the couch velocity to determine whether the tumor would be within 180° of that specific peak inhalation given the CT scanner coverage, pitch, rotation period, tumor size, and tumor motion amplitude (defined in units of centimeters per bellows signal). The imaged tumor motion amplitude was based on which inhalation peak would be imaged and the couch location at that time relative to the exhalation peak. This analysis provided a series of measured breathing motion amplitudes, which were compared against the 85th percentile motion, consistent with the proposed 4DCT protocol. Because the 4DCT scans would yield a single amplitude determination for each patient, errors in the amplitude measurement were considered systematic. Therefore, the largest 5% and smallest 5% of the measured amplitudes were selected to identify over‐and under‐determined motion amplitudes.Results:30% of the patients exhibited breathing amplitude overestimations of at least 27%, while 30% showed underestimations of at least 34%.Conclusion:For the majority of patients, the current system provided a high probability of correct breathing motion amplitude measurements. 30% had a significant chance of a systematic over‐ or under‐estimation of tumor motion. The proposed protocol will be immune to such irregularities because the entire breathing trace is used for breathing motion amplitude assessments.
SU‐E‐J‐34: Clinical Evaluation of Targeting Accuracy and Tractogrphy Delineation of Radiosurgery
Authors: Juh R , Suh T , Kim Y , Han J , Kim C , Oh C , Kim D 
Published: July 2014

Purpose:Focal radiosurgery is a common treatment modality for trigeminal neuralgia (TN), a neuropathic facial pain condition. Assessment of treatment effectiveness is primarily clinical, given the paucity of investigational tools to assess trigeminal nerve changes. The efficiency of radiosurgery is related to its highly precise targeting. We assessed clinically the targeting accuracy of radiosurgery with Gamma knife. We hypothesized that trigeminal tractography provides more information than 2D‐MR imaging, allowing detection of unique, focal changes in the target area after radiosurgery.Methods:Sixteen TN patients (2 females, 4 male, average age 65.3 years) treated with Gamma Knife radiosurgery, 40 Gy/50% isodose line underwent 1.5Tesla MR trigeminal nerve . Target accuracy was assessed from deviation of the coordinates of the target compared with the center of enhancement on post MRI. Radiation dose delivered at the borders of contrast enhancement was evaluatedResults:The median deviation of the coordinates between the intended target and the center of contrast enhancement was within 1mm. The radiation doses fitting within the borders of the contrast enhancement the target ranged from 37.5 to 40 Gy. Trigeminal tractography accurately detected the radiosurgical target. Radiosurgery resulted in 47% drop in FA values at the target with no significant change in FA outside the target, suggesting that radiosurgery primarily affects myelin. Tractography was more sensitive, since FA changes were detected regardless of trigeminal nerve enhancementConclusion:The median deviation found in clinical assessment of gamma knife treatment for TN Is low and compatible with its high rate of efficiency. DTI parameters accurately detect the effects of focal radiosurgery on the trigeminal nerve, serving as an in vivo imaging tool to study TN. This study is a proof of principle for further assessment of DTI parameters to understand the pathophysiology of TN and treatment effects
SU‐E‐J‐73: Generation of Volumetric Images with a Respiratory Motion Model Based On An External Surrogate Signal
Authors: Hurwitz M , Williams C , Mishra P , Dhou S , Lewis J 
Published: July 2014

Purpose:Respiratory motion during radiotherapy treatment can differ significantly from motion observed during imaging for treatment planning. Our goal is to use an initial 4DCT scan and the trace of an external surrogate marker to generate 3D images of patient anatomy during treatment.Methods:Deformable image registration is performed on images from an initial 4DCT scan. The deformation vectors are used to develop a patient‐specific linear relationship between the motion of each voxel and the trajectory of an external surrogate signal. Correlations in motion are taken into account with principal component analysis, reducing the number of free parameters. This model is tested with digital phantoms reproducing the breathing patterns of ten measured patient tumor trajectories, using five seconds of data to develop the model and the subsequent thirty seconds to test its predictions. The model is also tested with a breathing physical anthropomorphic phantom programmed to reproduce a patient breathing pattern.Results:The error (mean absolute, 95th percentile) over 30 seconds in the predicted tumor centroid position ranged from (0.8, 1.3) mm to (2.2, 4.3) mm for the ten patient breathing patterns. The model reproduced changes in both phase and amplitude of the breathing pattern. Agreement between prediction and truth over the entire image was confirmed by assessing the global voxel intensity RMS error. In the physical phantom, the error in the tumor centroid position was less than 1 mm for all images.Conclusion:We are able to reconstruct 3D images of patient anatomy with a model correlating internal respiratory motion with motion of an external surrogate marker, reproducing the expected tumor centroid position with an average accuracy of 1.4 mm. The images generated by this model could be used to improve dose calculations for treatment planning and delivered dose estimates.This work was partially funded by a research grant from Varian Medical Systems.
SU‐E‐J‐78: Internal Target Volume Delineation for Lung Tumors in Patients Treated with Robotic Radiosurgery
Authors: Descovich M , Pinnaduwage D , Kirby N , Gottschalk A , Yom S , Pouliot J , Braunstein S 
Published: July 2014

Purpose:To compare different approaches for Internal Target Volume (ITV) delineation for patients treated with fiducial‐free robotic radiosurgery for primary and metastatic lung tumors.Methods:Ten patients undergoing Lung‐Optimized Treatment (LOT) for robotic radiosurgery were imaged with inhale and exhale breath‐hold CT scans and 8‐phase 4DCT scan. We evaluated the differences in internal target volume (ITV) delineated using three approaches: 1) maximum intensity projection (MIP) images reconstructed from 4DCT scan (ITV‐MIP); 2) linear interpolation of Gross Tumor Volumes (GTV) segmented on inhale and exhale breath‐hold scans (ITV‐BH); 3) linear interpolation of GTV segmented on inhale and exhale phases of 4DCT scan (ITV‐2Phase). All contours were independently generated by the same radiation oncologist using lung window settings. Patients had ITV‐MIP volumes ranging from 1.5 to 146.9 cc (mean 36.8 cc) located in various parts of the lung. Volume overlap and matching index (MI) were calculated and compared. The MI between two volumes was defined as the ratio of their intersection to their union. MI of 1 indicates the volumes are identical; MI of 0 indicates that there is no overlap.Results:The three approaches generated very different results. The average (SD) MI for ITV‐MIP and ITV‐BH was 0.52 (0.24); for ITV‐MIP and ITV‐2Phase it was 0.69 (0.13); and for ITV‐BH and ITV‐2Phase was 0.57 (0.21), (ANOVA, p=0.16). Relative to the ITV‐MIP, the percentage of volume overlap was 72% (26%) and 90% (7%) for ITV‐BH and ITV‐2Phase, respectively (t‐test, p=0.05).Conclusion:Differences between ITV‐BH and ITV‐MIP are due to inconsistent lung filling at breath‐hold and nonlinear tumor motion. Therefore, methods to check breath‐hold scanning against regular patient breathing patterns should be developed. Whenever possible, ITV‐BH generated by the LOT workflow should be verified by 4DCT data.
SU‐E‐J‐80: Interplay Effect Between VMAT Intensity Modulation and Tumor Motion in Hypofractioned Lung Treatment, Investigated with 3D Pressage Dosimeter
Authors: Touch M , Wu Q , Oldham M 
Published: July 2014

Purpose:To demonstrate an embedded tissue equivalent presage dosimeter for measuring 3D doses in moving tumors and to study the interplay effect between the tumor motion and intensity modulation in hypofractioned Volumetric Modulated Arc Therapy(VMAT) lung treatment.Methods:Motion experiments were performed using cylindrical Presage dosimeters (5cm diameter by 7cm length) mounted inside the lung insert of a CIRS thorax phantom. Two different VMAT treatment plans were created and delivered in three different scenarios with the same prescribed dose of 18 Gy. Plan1, containing a 2 centimeter spherical CTV with an additional 2mm setup margin, was delivered on a stationary phantom. Plan2 used the same CTV except expanded by 1 cm in the Sup‐Inf direction to generate ITV and PTV respectively. The dosimeters were irradiated in static and variable motion scenarios on a Truebeam system. After irradiation, high resolution 3D dosimetry was performed using the Duke Large Field‐of‐view Optical‐CT Scanner, and compared to the calculated dose from Eclipse.Results:In the control case (no motion), good agreement was observed between the planned and delivered dose distributions as indicated by 100% 3D Gamma (3% of maximum planned dose and 3mm DTA) passing rates in the CTV. In motion cases gamma passing rates was 99% in CTV. DVH comparisons also showed good agreement between the planned and delivered dose in CTV for both control and motion cases. However, differences of 15% and 5% in dose to PTV were observed in the motion and control cases respectively.Conclusion:With very high dose nature of a hypofraction treatment, significant effect was observed only motion is introduced to the target. This can be resulted from the motion of the moving target and the modulation of the MLC. 3D optical dosimetry can be of great advantage in hypofraction treatment dose validation studies.
SU‐E‐J‐85: Leave‐One‐Out Perturbation (LOOP) Fitting Algorithm for Absolute Dose Film Calibration
Authors: Chu A , Feng W , Ahmad M , Chen Z , Nath R 
Published: July 2014

Purpose:To introduce an outliers‐recognition fitting routine for film dosimetry. It cannot only be flexible with any linear and non‐linear regression but also can provide information for the minimal number of sampling points, critical sampling distributions and evaluating analytical functions for absolute film‐dose calibration.Methods:The technique, leave‐one‐out (LOO) cross validation, is often used for statistical analyses on model performance. We used LOO analyses with perturbed bootstrap fitting called leave‐one‐out perturbation (LOOP) for film‐dose calibration . Given a threshold, the LOO process detects unfit points (“outliers”) compared to other cohorts, and a bootstrap fitting process follows to seek any possibilities of using perturbations for further improvement. After that outliers were reconfirmed by a traditional t‐test statistics and eliminated, then another LOOP feedback resulted in the final. An over‐sampled film‐dose‐ calibration dataset was collected as a reference (dose range: 0‐800cGy), and various simulated conditions for outliers and sampling distributions were derived from the reference. Comparisons over the various conditions were made, and the performance of fitting functions, polynomial and rational functions, were evaluated.Results:(1) LOOP can prove its sensitive outlier‐recognition by its statistical correlation to an exceptional better goodness‐of‐fit as outliers being left‐out. (2) With sufficient statistical information, the LOOP can correct outliers under some low‐sampling conditions that other “robust fits”, e.g. Least Absolute Residuals, cannot. (3) Complete cross‐validated analyses of LOOP indicate that the function of rational type demonstrates a much superior performance compared to the polynomial. Even with 5 data points including one outlier, using LOOP with rational function can restore more than a 95% value back to its reference values, while the polynomial fitting completely failed under the same conditions.Conclusion:LOOP can cooperate with any fitting routine functioning as a “robust fit”. In addition, it can be set as a benchmark for film‐dose calibration fitting performance.
SU‐E‐J‐86: Lobar Lung Function Quantification by PET Galligas and CT Ventilation Imaging in Lung Cancer Patients
Authors: Eslick E , Bailey D , Bailey E , Kipritidis J , Keall P 
Published: July 2014

Purpose:The purpose of this study was to quantify the lobar lung function using the novel PET Galligas ([68Ga]‐carbon nanoparticle) ventilation imaging and the investigational CT ventilation imaging in lung cancer patients pre‐treatment.Methods:We present results on our first three lung cancer patients (2 male, mean age 78 years) as part of an ongoing ethics approved study. For each patient a PET Galligas ventilation (PET‐V) image and a pair of breath hold CT images (end‐exhale and end‐inhale tidal volumes) were acquired using a Siemens Biograph PET CT. CT‐ventilation (CT‐V) images were created from the pair of CT images using deformable image registration (DIR) algorithms and the Hounsfield Unit (HU) ventilation metric. A comparison of ventilation quantification from each modality was done on the lobar level and the voxel level. A Bland‐Altman plot was used to assess the difference in mean percentage contribution of each lobe to the total lung function between the two modalities. For each patient, a voxel‐wise Spearmans correlation was calculated for the whole lungs between the two modalities.Results:The Bland‐Altman plot demonstrated strong agreement between PET‐V and CT‐V for assessment of lobar function (r=0.99, p<0.001; range mean difference: −5.5 to 3.0). The correlation between PET‐V and CT‐V at the voxel level was moderate(r=0.60, p<0.001).Conclusion:This preliminary study on the three patients data sets demonstrated strong agreement between PET and CT ventilation imaging for the assessment of pre‐treatment lung function at the lobar level. Agreement was only moderate at the level of voxel correlations. These results indicate that CT ventilation imaging has potential for assessing pre‐treatment lobar lung function in lung cancer patients.
SU‐E‐J‐89: Motion Effects On Organ Dose in Respiratory Gated Stereotactic Body Radiation Therapy
Authors: Wang T , Khan M , Landry J , Rajpara R , Hawk N , Zhu L 
Published: July 2014

Purpose:Existing reports on gated radiation therapy focus mainly on optimizing dose delivery to the target structure. This work investigates the motion effects on radiation dose delivered to organs at risk (OAR) in respiratory gated stereotactic body radiation therapy (SBRT). A new algorithmic tool of dose analysis is developed to evaluate the optimality of gating phase for dose sparing on OARs while ensuring adequate target coverage.Methods:Eight patients with pancreatic cancer were treated on a phase I prospective study employing 4DCT‐based SBRT. For each patient, 4DCT scans are acquired and sorted into 10 respiratory phases (inhale‐exhale‐ inhale). Treatment planning is performed on the average CT image. The average CT is spatially registered to other phases. The resultant displacement field is then applied on the plan dose map to estimate the actual dose map for each phase. Dose values of each voxel are fitted to a sinusoidal function. Fitting parameters of dose variation, mean delivered dose and optimal gating phase for each voxel over respiration cycle are mapped on the dose volume.Results:The sinusoidal function accurately models the dose change during respiratory motion (mean fitting error 4.6%). In the eight patients, mean dose variation is 3.3 Gy on OARs with maximum of 13.7 Gy. Two patients have about 100cm3 volumes covered by more than 5 Gy deviation. The mean delivered dose maps are similar to plan dose with slight deformation. The optimal gating phase highly varies across the patient, with phase 5 or 6 on about 60% of the volume, and phase 0 on most of the rest.Conclusion:A new algorithmic tool is developed to conveniently quantify dose deviation on OARs from plan dose during the respiratory cycle. The proposed software facilitates the treatment planning process by providing the optimal respiratory gating phase for dose sparing on each OAR.
SU‐E‐J‐94: Positioning Errors Resulting From Using Bony Anatomy Alignment for Treating SBRT Lung Tumor
Authors: Frame C , Ding G 
Published: July 2014

Purpose:To quantify patient setups errors based on bony anatomy registration rather than 3D tumor alignment for SBRT lung treatments.Method:A retrospective study was performed for patients treated with lung SBRT and imaged with kV cone beam computed tomography (kV‐CBCT) image‐guidance. Daily CBCT images were registered to treatment planning CTs based on bony anatomy alignment and then inter‐fraction tumor movement was evaluated by comparing shift in the tumor center in the medial‐lateral, anterior‐posterior, and superior‐inferior directions. The PTV V100% was evaluated for each patient based on the average daily tumor displacement to assess the impact of the positioning error on the target coverage when the registrations were based on bony anatomy. Of the 35 patients studied, 15 were free‐breathing treatments, 10 used abdominal compression with a stereotactic body frame, and the remaining 10 were performed with BodyFIX vacuum bags.Results:For free‐breathing treatments, the range of tumor displacement error is between 1–6 mm in the medial‐lateral, 1–13 mm in the anterior‐posterior, and 1–7 mm in the superior‐inferior directions. These positioning errors lead to 6–22% underdose coverage for PTV – V100% . Patients treated with abdominal compression immobilization showed positional errors of 0–4mm mediallaterally, 0–3mm anterior‐posteriorly, and 0–2 mm inferior‐superiorly with PTV – V100% underdose ranging between 6–17%. For patients immobilized with the vacuum bags, the positional errors were found to be 0–1 mm medial‐laterally, 0–1mm anterior‐posteriorly, and 0–2 mm inferior‐superiorly with PTV – V100% under dose ranging between 5–6% only.Conclusion:It is necessary to align the tumor target by using 3D image guidance to ensure adequate tumor coverage before performing SBRT lung treatments. The BodyFIX vacuum bag immobilization method has the least positioning errors among the three methods studied when bony anatomy is used for registration.
SU‐E‐J‐101: Retroactive Calculation of TLD and Film Dose in Anthropomorphic Phantom as Assessment of Updated TPS Performance
Authors: Alkhatib H , Oves S 
Published: July 2014

Purpose:To demonstrate a quick and comprehensive method verifying the accuracy of the updated dose model by recalculating dose distribution in an anthropomorphic phantom with a new version of the TPS and comparing the results to measured values.Methods:CT images and IMRT plan of an RPC anthropomorphic head phantom, previously calculated by Pinnacle 9.0, was re‐computed using Pinnacle 9.2 and 9.6. The dosimeters within the phantom include four TLD capsules representing a primary PTV, two TLD capsules representing a secondary PTV, and two TLD capsules representing an organ at risk. Also included were three sheets of Gafchromic film. Performance of the updated TPS version was assessed by recalculating point doses and dose profiles corresponding to TLD and film position respectively and then comparing the results to reported values by the RPC.Results:Comparing calculated doses to reported measured doses from the RPC yielded an average disagreement of 1.48%, 2.04% and 2.10% for versions 9.0, 9.2, 9.6 respectively. Computed doses points all meet the RPC's passing criteria with the exception of the point representing the superior organ at risk in version 9.6. However, qualitative analysis of the recalculated dose profiles showed improved agreement with those of the RPC, especially in the penumbra region.Conclusion:This work has demonstrated the calculation results of Pinnacle 9.2 and 9.6 vs 9.0 version. Additionally, this study illustrates a method for the user to gain confidence upgrade to a newer version of the treatment planning system.
SU‐E‐J‐104: Single Photon Image From PET with Insertable SPECT Collimator for Boron Neutron Capture Therapy: A Feasibility Study
Authors: Jung J , Yoon D , Hong K , Suh T 
Published: July 2014

Purpose:The aim of our proposed system is to confirm the feasibility of extraction of two types of images from one positron emission tomography (PET) module with an insertable collimator for brain tumor treatment during the BNCT.Methods:Data from the PET module, neutron source, and collimator was entered in the Monte Carlo n‐particle extended (MCNPX) source code. The coincidence events were first compiled on the PET detector, and then, the events of the prompt gamma ray were collected after neutron emission by using a single photon emission computed tomography (SPECT) collimator on the PET. The obtaining of full width at half maximum (FWHM) values from the energy spectrum was performed to collect effective events for reconstructed image. In order to evaluate the images easily, five boron regions in a brain phantom were used. The image profiles were extracted from the region of interest (ROI) of a phantom. The image was reconstructed using the ordered subsets expectation maximization (OSEM) reconstruction algorithm. The image profiles and the receiver operating characteristic (ROC) curve were compiled for quantitative analysis from the two kinds of reconstructed image.Results:The prompt gamma ray energy peak of 478 keV appeared in the energy spectrum with a FWHM of 41 keV (6.4%). On the basis of the ROC curve in Region A to Region E, the differences in the area under the curve (AUC) of the PET and SPECT images were found to be 10.2%, 11.7%, 8.2% (center, Region C), 12.6%, and 10.5%, respectively.Conclusion:We attempted to acquire the PET and SPECT images simultaneously using only PET without an additional isotope. Single photon images were acquired using an insertable collimator on a PET detector.This research was supported by the Leading Foreign Research Institute Recruitment Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, Information and Communication Technologies (ICT) & Future Planning (MSIP)(Grant No.2009 00420) and the Radiation Technology R&D program (Grant No.2013M2A2A7043498), Republic of Korea.