bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐E‐J‐16: Automatic Image Contrast Enhancement Based On Automatic Parameter Optimization for Radiation Therapy Setup Verification
Authors: Qiu J , Li H. Harlod , Zhang T , Ma F , Yang D 
Published: June 2015

Purpose:In RT patient setup 2D images, tissues often cannot be seen well due to the lack of image contrast. Contrast enhancement features provided by image reviewing software, e.g. Mosaiq and ARIA, require manual selection of the image processing filters and parameters thus inefficient and cannot be automated. In this work, we developed a novel method to automatically enhance the 2D RT image contrast to allow automatic verification of patient daily setups as a prerequisite step of automatic patient safety assurance.Methods:The new method is based on contrast limited adaptive histogram equalization (CLAHE) and high‐pass filtering algorithms. The most important innovation is to automatically select the optimal parameters by optimizing the image contrast. The image processing procedure includes the following steps: 1) background and noise removal, 2) hi‐pass filtering by subtracting the Gaussian smoothed Result, and 3) histogram equalization using CLAHE algorithm. Three parameters were determined through an iterative optimization which was based on the interior‐point constrained optimization algorithm: the Gaussian smoothing weighting factor, the CLAHE algorithm block size and clip limiting parameters. The goal of the optimization is to maximize the entropy of the processed Result.Results:A total 42 RT images were processed. The results were visually evaluated by RT physicians and physicists. About 48% of the images processed by the new method were ranked as excellent. In comparison, only 29% and 18% of the images processed by the basic CLAHE algorithm and by the basic window level adjustment process, were ranked as excellent.Conclusion:This new image contrast enhancement method is robust and automatic, and is able to significantly outperform the basic CLAHE algorithm and the manual window‐level adjustment process that are currently used in clinical 2D image review software tools.
SU‐E‐J‐21: Setup Variability of Colorectal Cancer Patients Treated in the Prone Position and Dosimetric Comparison with the Supine Position
Authors: Kim A , Foster J , Chu W , Karotki A 
Published: June 2015

Purpose:Many cancer centers treat colorectal patients in the prone position on a belly board to minimize dose to the small bowel. That may potentially Result in patient setup instability with corresponding impact on dose delivery accuracy for highly conformal techniques such as IMRT/VMAT. Two aims of this work are 1) to investigate setup accuracy of rectum patients treated in the prone position on a belly board using CBCT and 2) to evaluate dosimetric impact on bladder and small bowel of treating rectum patients in supine vs. prone position.Methods:For the setup accuracy study, 10 patients were selected. Weekly CBCTs were acquired and matched to bone. The CBCT‐determined shifts were recorded. For the dosimetric study, 7 prone‐setup patients and 7 supine‐setup patients were randomly selected from our clinical database. Various clinically relevant dose volume histogram values were recorded for the small bowel and bladder.Results:The CBCT‐determined rotational shifts had a wide variation. For the dataset acquired at the time of this writing, the ranges of rotational setup errors for pitch, roll, and yaw were [−3.6° 4.7°], [−4.3° 3.2°], and [−1.4° 1.4°]. For the dosimetric study: the small bowel V(45Gy) and mean dose for the prone position was 5.6±12.1% and 18.4±6.2Gy (ranges indicate standard deviations); for the supine position the corresponding dose values were 12.9±15.8% and 24.7±8.8Gy. For the bladder, the V(30Gy) and mean dose for prone position were 68.7±12.7% and 38.4±3.3Gy; for supine position these dose values were 77.1±13.7% and 40.7±3.1Gy.Conclusion:There is evidence of significant rotational instability in the prone position. The OAR dosimetry study indicates that there are some patients that may still benefit from the prone position, though many patients can be safely treated supine.
SU‐E‐J‐22: A Feasibility Study On KV‐Based Whole Breast Radiation Patient Setup
Authors: Huang Q , Zhang M , Yue N , Chen T 
Published: June 2015

Purpose:In room kilovoltage x‐ray (kV) imaging provides higher contrast than Megavoltage (MV) imaging with faster acquisition time compared with on‐board cone‐beam computed tomography (CBCT), thus improving patient setup accuracy and efficiency. In this study we evaluated the clinical feasibility of utilizing kV imaging for whole breast radiation patient setup.Methods:For six breast cancer patients with whole breast treatment plans using two opposed tangential fields, MV‐based patient setup was conducted by aligning patient markers with in room lasers and MV portal images. Beam‐eye viewed kV images were acquired using Varian OBI system after the set up process. In house software was developed to transfer MLC blocks information overlaying onto kV images to demonstrate the field shape for verification. KV‐based patient digital shift was derived by performing rigid registration between kV image and the digitally reconstructed radiography (DRR) to align the bony structure. This digital shift between kV‐based and MV‐based setup was defined as setup deviation.Results:Six sets of kV images were acquired for breast patients. The mean setup deviation was 2.3mm, 2.2mm and 1.8mm for anterior‐posterior, superior‐inferior and left‐right direction respectively. The average setup deviation magnitude was 4.3±1.7mm for six patients. Patient with large breast had a larger setup deviation (4.4–6.2mm). There was no strong correlation between MV‐based shift and setup deviation.Conclusion:A preliminary clinical workflow for kV‐based whole breast radiation setup was established and tested. We observed setup deviation of the magnitude below than 5mm. With the benefit of providing higher contrast and MLC block overlaid on the images for treatment field verification, it is feasible to use kV imaging for breast patient setup.
SU‐E‐J‐28: Gantry Speed Significantly Affects Image Quality and Imaging Dose for 4D Cone‐Beam Computed Tomography On the Varian Edge Platform
Authors: Santoso A , Song K , Gardner S , Chetty I , Wen N 
Published: June 2015

Purpose:4D‐CBCT facilitates assessment of tumor motion at treatment position. We investigated the effect of gantry speed on 4D‐CBCT image quality and dose using the Varian Edge On‐Board Imager (OBI).Methods:A thoracic protocol was designed using a 125 kVp spectrum. Image quality parameters were obtained via 4D acquisition using a Catphan phantom with a gating system. A sinusoidal waveform was executed with a five second period and superior‐inferior motion. 4D‐CBCT scans were sorted into 4 and 10 phases. Image quality metrics included spatial resolution, contrast‐to‐noise ratio (CNR), uniformity index (UI), Hounsfield unit (HU) sensitivity, and RMS error (RMSE) of motion amplitude. Dosimetry was accomplished using Gafchromic XR‐QA2 films within a CIRS Thorax phantom. This was placed on the gating phantom using the same motion waveform.Results:High contrast resolution decreased linearly from 5.93 to 4.18 lp/cm, 6.54 to 4.18 lp/cm, and 5.19 to 3.91 lp/cm for averaged, 4 phase, and 10 phase 4DCBCT volumes respectively as gantry speed increased from 1.0 to 6.0 degs/sec. CNRs decreased linearly from 4.80 to 1.82 as the gantry speed increased from 1.0 to 6.0 degs/sec, respectively. No significant variations in UIs, HU sensitivities, or RMSEs were observed with variable gantry speed. Ion chamber measurements compared to film yielded small percent differences in plastic water regions (0.1–9.6%), larger percent differences in lung equivalent regions (7.5–34.8%), and significantly larger percent differences in bone equivalent regions (119.1–137.3%). Ion chamber measurements decreased from 17.29 to 2.89 cGy with increasing gantry speed from 1.0 to 6.0 degs/sec.Conclusion:Maintaining technique factors while changing gantry speed changes the number of projections used for reconstruction. Increasing the number of projections by decreasing gantry speed decreases noise, however, dose is increased. The future of 4DCBCT's clinical utility relies on further investigation of image optimization.
SU‐E‐J‐29: Automatic Image Registration Performance of Three IGRT Systems for Prostate Radiotherapy
Authors: Barber J , Sykes J , Holloway L , Thwaites D 
Published: June 2015

Purpose:To compare the performance of an automatic image registration algorithm on image sets collected on three commercial image guidance systems, and explore its relationship with imaging parameters such as dose and sharpness.Methods:Images of a CIRS Virtually Human Male Pelvis phantom (VHMP) were collected on the CBCT systems of Varian TrueBeam/OBI and Elekta Synergy/XVI linear accelerators, across a range of mAs settings; and MVCT on a Tomotherapy Hi‐ART accelerator with a range of pitch. Using the 6D correlation ratio algorithm of XVI, each image was registered to a mask of the prostate volume with a 5 mm expansion. Registrations were repeated 100 times, with random initial offsets introduced to simulate daily matching. Residual registration errors were calculated by correcting for the initial phantom set‐up error. Automatic registration was also repeated after reconstructing images with different sharpness filters.Results:All three systems showed good registration performance, with residual translations <0.5mm (1σ) for typical clinical dose and reconstruction settings. Residual rotational error had larger range, with 0.8°, 1.2° and 1.9° for 1σ in XVI, OBI and Tomotherapy respectively. The registration accuracy of XVI images showed a strong dependence on imaging dose, particularly below 4mGy. No evidence of reduced performance was observed at the lowest dose settings for OBI and Tomotherapy, but these were above 4mGy. Registration failures (maximum target registration error > 3.6 mm on the surface of a 30mm sphere) occurred in 5% to 10% of registrations. Changing the sharpness of image reconstruction had no significant effect on registration performance.Conclusions:Using the present automatic image registration algorithm, all IGRT systems tested provided satisfactory registrations for clinical use, within a normal range of acquisition settings.
SU‐E‐J‐30: The Effect of Planning CT Slice Thickness On Evaluation of SRS Target Localization Accuracy
Authors: Briceno J , Li H , Huang Y , Wen N , Chetty I 
Published: June 2015

Purpose:To evaluate the effect of planning CT slice thickness on SRS target localization accuracy on Varian Edge SRS treatment platform.Methods:A metal BB of diameter 5 mm was inserted in a Rando head phantom. Planning CTs were scanned with 0.8, 2 and 3 mm slice thickness respectively. The center of BB was setup as isocenter and tattoos were marked on phantom surface. The phantom was initially aligned using laser and tattoos, then a CBCT was acquired and 6‐degree of freedom (DOF) image registration was performed based on bony anatomy. The 6D couch correction was applied. A verification CBCT was taken to evaluate couch corrections. Three orthogonal pairs of images (MV‐MV, KV‐KV and MVKV), were also taken to verify the position of the phantom using a 2D‐3D registration algorithm. Winston‐Lutz tests were taken at 12 combinations of gantry, collimator and couch angles using 1×1cm MLC aperture and 10mm circular cone.Results:The vector lengths of the residual error measured with verification CBCT were 0.3, 0.2 and 0.2 mm for the planning CT of 0.8, 2 and 3 mm slice thicknesses respectively. Residual setup error vector lengths for 0.8, 2, and 3 mm CT measured by orthogonal pair were as following: a) MV‐MV: 0.2, 0.5, 0.5mm; b) KV‐KV: 0.2, 0.3, 0.3mm; c)MV‐KV: 0.1, 0.6, 0.3mm respectively. The vector lengths for the Winston‐Lutz tests were: a) MLC: 0.55, 0.32, and 0.2mm; b) CONE: 0.16, 0.17, and 0.29mm for slice thickness of 0.8, 2, and 3mm respectively.Conclusion:The residual setup error in this study measured by the 2D‐3D algorithm was comparable to that of the 3D‐3D algorithm. The planning CT slice thickness in the range of 0.8 to 2 mm has no significant impact on the evaluation of the residual setup error and the Result of Winston‐Lutz test.
SU‐E‐J‐33: Comparison Between Soft Tissue Alignment and Bony Alignment for Pancreatic Cancer Radiotherapy
Authors: Suh Y , Crane C , Krishnan S , Das P , Koay E , Beddar S 
Published: June 2015

PurposeAn IGRT modality for pancreatic cancer treatment with dose escalation at our institution is in‐room daily CT imaging. The purpose of this study is to assess the difference between soft tissue alignment and bony alignment for pancreatic tumor localization.MethodsEighteen patients with pancreatic tumors who underwent IMRT treatment with an inspiration breath‐hold technique between July 2012 and February 2015 are included in this study. Prior to each treatment, a CT scan was acquired. The CT image guidance started with auto‐alignment to either the bony anatomy (vertebral bodies) or fiducials (for the six patients with the stent in/near the tumor) and then, when necessary, manual adjustments were made based on soft tissue alignment using clinical software (CT‐Assisted Targeting system). The difference between soft tissue alignment and bony/fiducial alignment was evaluated.ResultsOf all 380 treatments, manual adjustment was made in 225 treatments, ranging from 11% (3 treatments out of 28) to 96% (27 treatments out of 28) per patient. The mean of the difference between soft tissue alignment and bony/fiducial alignment per patient ranged from −3.6 to 0.3 mm, −1.5 to 2.8 mm, and −3.3 to 3.4 mm in the AP, SI, and RL directions, respectively. The maximum difference over all treatments was −9.5, −14.6, and −14.6 mm in the AP, SI, and RL directions, respectively.ConclusionAbout 60% of the time, manual adjustment based on soft tissue alignment was required. The extent of manual adjustment was usually small but varied significantly from patient to patient. The ultimate goal of the IGRT modality using daily CT imaging is not to fully cover the target but to spare organs‐at‐risk as much as possible to avoid them moving into higher dose gradients than accepted in the treatment plan. To this end, manual adjustment based on soft tissue alignment is critically important.
SU‐E‐J‐36: Comparison of CBCT Image Quality for Manufacturer Default Imaging Modes
Authors: Nelson G 
Published: June 2015

PurposeCBCT is being increasingly used in patient setup for radiotherapy. Often the manufacturer default scan modes are used for performing these CBCT scans with the assumption that they are the best options. To quantitatively assess the image quality of these scan modes, all of the scan modes were tested as well as options with the reconstruction algorithm.MethodsA CatPhan 504 phantom was scanned on a TrueBeam Linear Accelerator using the manufacturer scan modes (FSRT Head, Head, Image Gently, Pelvis, Pelvis Obese, Spotlight, & Thorax). The Head mode scan was then reconstructed multiple times with all filter options (Smooth, Standard, Sharp, & Ultra Sharp) and all Ring Suppression options (Disabled, Weak, Medium, & Strong). An open source ImageJ tool was created for analyzing the CatPhan 504 images.ResultsThe MTF curve was primarily dictated by the voxel size and the filter used in the reconstruction algorithm. The filters also impact the image noise. The CNR was worst for the Image Gently mode, followed by FSRT Head and Head. The sharper the filter, the worse the CNR. HU varied significantly between scan modes. Pelvis Obese had lower than expected HU values than most while the Image Gently mode had higher than expected HU values. If a therapist tried to use preset window and level settings, they would not show the desired tissue for some scan modes.ConclusionKnowing the image quality of the set scan modes, will enable users to better optimize their setup CBCT. Evaluation of the scan mode image quality could improve setup efficiency and lead to better treatment outcomes.
SU‐E‐J‐38: Improved DRR Image Quality Using Polyetheretherketone (PEEK) Fiducial in Image Guided Radiotherapy (IGRT)
Authors: Shen S , Jacob R , Popple R , Duan J , Wu X , Cardan R , Brezovich I 
Published: June 2015

PurposeFiducial‐based imaging is often used in IGRT. Traditional gold fiducial marker often has substantial reconstruction artifacts. These artifacts Result in poor image quality of DRR for online kV‐to‐DRR matching. This study evaluated the image quality of PEEK in DRR in static and moving phantom.MethodsCT scan of the Gold and PEEK fiducial (both 1×3 mm) was acquired in a 22 cm cylindrical phantom filled with water. Image artifacts was evaluated with maximum CT value deviated from water due to artifacts; volume of artifacts in 10×10 cm in the center slice; maximum length of streak artifacts from the fiducial. DRR resolution were measured using FWHM and FWTM. 4DCT of PEEK fiducial was acquired with the phantom moving sinusoidally in superior‐inferior direction. Motion artifacts were assessed for various 4D phase angles.ResultsThe maximum CT value deviation was −174 for Gold and −24 for PEEK. The volume of artifacts in a 10x10 cm 3 mm slice was 0.369 for Gold and 0.074 cm3 for PEEK. The maximum length of streak artifact was 80mm for Gold and 7 mm for PEEK. PEEK in DRR, FWHM was close to actual (1.0 mm for Gold and 1.1 mm for PEEK). FWTM was 1.8 mm for Gold and 1.3 mm for PEEK in DRR. Barrel motion artifact of PEEK fiducial was noticeable for free‐breathing scan. The apparent PEEK length due to residual motion was in close agreement with the calculated length (13 mm for 30–70 phase, 10 mm in 40–60 phase).ConclusionStreak artifacts on planning CT associated with use of gold fiducial can be significantly reduced by PEEK fiducial, while having adequate kV image contrast. DRR image resolution at FWTM was improved from 1.8 mm to 1.3 mm. Because of this improvement, we have been routinely use PEEK for liver IGRT.
SU‐E‐J‐40: Improving Uncertainty of Prostate Positioning by Using Implanted Fiducial Marker‐Based Hybrid Evaluation Combined with KV Portal Imaging and CBCT for Prostate IMRT
Authors: Hirose K , Sato M , Aoki M , Kawaguchi H , Akimoto H , Hatayama Y , Komai F , Sohma M , Obara H , Suzuki M , Takai Y 
Published: June 2015

PurposeThe aim of this work was to present our single‐institution experience with fiducial marker‐based hybrid evaluation of prostate positioning combined with orthogonal kV portal image which inform the central position of prostate and CBCT which provides the information on localization of the peripheral structures.MethodsTwenty‐five patients received prostate IMRT with daily localization by use of implanted fiducials. Orthogonal kV portal imaging and CBCT preceded all 977 treatments. After shifts in the AP, SI, and LR dimensions were made from kV imaging, following another shifts were made when more than 2‐mm prostate deviation as total sum of all dimensions were detected by CBCT. Post‐treatment kV imaging and CBCT were also obtained in 203 treatments (21%). Shifts between two techniques were analyzed, and compared by Bland‐Altman limits of agreement. Intrafraction motion and PTV margin were determined from shifts between pre‐ and post‐treatment in each technique.ResultsPre‐treatment isocenter shift were made based on CBCT in addition to kV imaging in 315 (32%) treatments. Mean differences between kV imaging and CBCT in the AP/SI/LR were −0.10±0.93/− 0.06±0.91/0.15±0.51 mm. The correlation between these techniques was follows: R2 = 0.90, 0.93, 0.94. Bland‐Altman 95% confidence intervals were −1.7 to 1.9/−1.7 to 1.8/−1.2 to 0.8 mm, without significant trends. Intrafraction motion for prostate obtained from pre‐ and post‐CBCT were 0.00±0.15/0.02±1.49/0.15±0.64 mm, which were smaller than the results from kV imaging (0.42±1.90/0.12±1.98/0.26±0.80 mm). PTV margins calculated from the results of CBCT were also smaller than kV imaging (3.95 mm vs 5.15 mm, 4.02 mm vs 5.34 mm, 1.75 mm vs 2.18 mm).ConclusionHybrid evaluation combined with identification of cranial and caudal edge of prostate by using CBCT compensates the uncertainty of prostate positioning originated from independent utilization of kV portal imaging, which enables to set PTV margins that reflect more realistic intrafraction organ motion.
SU‐E‐J‐43: Accuracy and Dynamic Range of Optical‐Surface‐Imaging (OSI)‐Based Spirometry
Authors: Huang H , Wei J , Chen Q , Gaebler C , Zatcky J , Mechalakos J , Li G 
Published: June 2015

PurposeTo assess the accuracy of optical‐surface‐imaging (OSI)‐based spirometry for tidal volume (TV) measurement using a conventional spirometer and the usability under different breathing conditions.MethodsVideo‐based OSI with high‐speed image capture (HSIC) and a Bernoullitype spirometer were applied simultaneously to measure dynamic TVs of human subjects. Six healthy volunteers participated in an IRB protocol study. The subjects lied on 7.5°–10° upward‐tilted breast board while breathe through the spirometer. The entire torso was imaged to capture all respiration‐induced external motions. Five breathing exercises were performed, including free breathing (FB), belly breathing (BB), chest breathing (CB), deep breathing (DB), and breath holding (BH) with pseudo‐breathing motions. The HSIC data were acquired at 5Hz and 3D surfaces were reconstructed retrospectively. The volume of interest was manually delineated and applied to all surface images for batch‐mode computation. Dynamic TVs were calculated by subtracting the volume at full exhalation. The thorax and abdomen were separated and the breathing pattern (BPv=ΔVthorax/ΔVtorso) was calculated for each exercise. The spirometer was calibrated before experiments and baseline drifts were corrected by zeroing the background pressure initially and during involuntary breath hold, and resetting the baseline by linear regression of five consecutive fullexhalation points. The two TV datasets were compared.ResultsFor FB, the average difference among all subjects is −3.2±6.0%. From BB, CB to DB, the discrepancies increase to −3.8±6.0%, −6.4±4.3%, and −1.1±14.0%, respectively. A near full range of BP (0.1–1.0) was observed. During BH, a constant TV was obtained despite the torso motion, conforming to volume conservation and suggesting diaphragmatic motion at the same TV.ConclusionThe accuracy and dynamic range of OSI‐based spirometry has been assessed by using conventional spirometry as the reference among six healthy volunteers. The resultant discrepancy is acceptable (except DB), suggesting this new spirometry is of promising utility under common breathing conditions.This study is in part supported by NIH (U54CA137788 and U54CA132378).