bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐F‐J‐114: On‐Treatment Imagereconstruction Using Transit Images of Treatment Beams Through Patient and Thosethrough Planning CT Images
Authors: Lee H , Cheong K , Jung J , Cho S , Jung S , Kim J , Yeo I 
Published: July 2016

Purpose:To reconstruct patient images at the time of radiation delivery using measured transit images of treatment beams through patient and calculated transit images through planning CT images.Methods:We hypothesize that the ratio of the measured transit images to the calculated images may provide changed amounts of the patient image between times of planning CT and treatment. To test, we have devised lung phantoms with a tumor object (3‐cm diameter) placed at iso‐center (simulating planning CT) and off‐center by 1 cm (simulating treatment). CT images of the two phantoms were acquired; the image of the off‐centered phantom, unavailable clinically, represents the reference on‐treatment image in the image quality of planning CT. Cine‐transit images through the two phantoms were also acquired in EPID from a non‐modulated 6 MV beam when the gantry was rotated 360 degrees; the image through the centered phantom simulates calculated image. While the current study is a feasibility study, in reality our computational EPID model can be applicable in providing accurate transit image from MC simulation. Changed MV HU values were reconstructed from the ratio between two EPID projection data, converted to KV HU values, and added to the planning CT, thereby reconstructing the on‐treatment image of the patient limited to the irradiated region of the phantom.Results:The reconstructed image was compared with the reference image. Except for local HU differences>200 as a maximum, excellent agreement was found. The average difference across the entire image was 16.2 HU.Conclusion:We have demonstrated the feasibility of a method of reconstructing on‐treatment images of a patient using EPID image and planning CT images. Further studies will include resolving the local HU differences and investigation on the dosimetry impact of the reconstructed image.
SU‐F‐J‐133: Adaptive Radiation Therapy with a Four‐Dimensional Dose Calculation Algorithm That Optimizes Dose Distribution Considering Breathing Motion
Authors: Ali I , Alsbou N , Algan O , Ahmad S 
Published: July 2016

Purpose:To model patient motion and produce four‐dimensional (4D) optimized dose distributions that consider motion‐artifacts in the dose calculation during the treatment planning process.Methods:An algorithm for dose calculation is developed where patient motion is considered in dose calculation at the stage of the treatment planning. First, optimal dose distributions are calculated for the stationary target volume where the dose distributions are optimized considering intensity‐modulated radiation therapy (IMRT). Second, a convolution‐kernel is produced from the best‐fitting curve which matches the motion trajectory of the patient. Third, the motion kernel is deconvolved with the initial dose distribution optimized for the stationary target to produce a dose distribution that is optimized in four‐dimensions. This algorithm is tested with measured doses using a mobile phantom that moves with controlled motion patterns.Results:A motion‐optimized dose distribution is obtained from the initial dose distribution of the stationary target by deconvolution with the motion‐kernel of the mobile target. This motion‐optimized dose distribution is equivalent to that optimized for the stationary target using IMRT. The motion‐optimized and measured dose distributions are tested with the gamma index with a passing rate of >95% considering 3% dose‐difference and 3mm distance‐to‐agreement. If the dose delivery per beam takes place over several respiratory cycles, then the spread‐out of the dose distributions is only dependent on the motion amplitude and not affected by motion frequency and phase. This algorithm is limited to motion amplitudes that are smaller than the length of the target along the direction of motion.Conclusion:An algorithm is developed to optimize dose in 4D. Besides IMRT that provides optimal dose coverage for a stationary target, it extends dose optimization to 4D considering target motion. This algorithm provides alternative to motion management techniques such as beam‐gating or breath‐holding and has potential applications in adaptive radiation therapy.
SU‐F‐J‐139: Amplitude of Low Frequency Fluctuation(ALFF) and Regional Homogeneity (ReHo) Study of the Respiration Motion Control Byhypnosis
Authors: Liu Y , Li R , Xie Y 
Published: July 2016

Purpose:Respiration control by hypnosis is a method in reducing the detriment to the healthy organs or organizations for patients during radiotherapy, especially for lung and abdomen cancer (Fig.1). It's hypothesized that there exists alterations neurological brain activity during the hypnosis state of respiratory motion control in comparison with resting state.Methods:Thirteen healthy volunteers were organized to participate in a hypnosis experiment that consisted of two sectional scans of functional magnetic resonance imaging (fMRI), rest state condition (RSC) scanning and hypnosis state condition (HSC) scanning. In addition, the coronal section of the lung was scanned during both conditions. During the hypnosis scan, the volunteers were under the hypnotists’ guidance to keep peace and stable respiration. To evaluate the altered physiological performance of hypnosis in the respiratory control, three conventional indicators ALFF/fALFF (0.01–0.08Hz) and ReHo, were applied to identify the difference.Results:Compared with RSC, HSC showed significant (p<0.05) higher ReHo in superior temporal gyrus, middle temporal gyrus, frontal lobe, middle occipital gyrus, parietal lobe, cerebellum anterior Lobe and lingual gyrus, and left brainstem (Fig.2). While significant lower ReHo in middle frontal gyrus, superior frontal gyrus, inferior semi‐lunar lobule, sub‐lobar and limbic lobe (Fig.2). As for the ALFF results, significant higher value of HSC was observed in superior temporal gyrus, middle temporal gyrus, middle occipital gyrus, middle occipital gyrus, cerebellum anterior lobe, lingual gyrus, sub‐lobar, limbic lobe, and lower in cerebellum posterior lobe, inferior semi‐lunar lobule, inferior parietal lobule right middle frontal gyrus, cerebellar tonsil (Fig.3). The results of fALFF were similar to ALFF (Fig.4). The above results demonstrated that most significant regions of brain were uniform between ReHo and ALFF/fALFF.Conclusion:Hypnosis is a new psychological and helpful technology for respiration control. This study provides new insights of neurological brain activity during hypnosis of respiration control.This work is supported by grants from Guangdong Innovative Research Team Program of China (Grant No. 2011S013), National 863 Programs of China (Grant Nos. 2012AA02A604 and 2015AA043203), the National High‐tech R&D Program for Young Scientists by the Ministry of Science and Technology of China (Grant No. 2015AA020917)
SU‐F‐J‐155: Evaluation of Transcytolemmal Water Exchange Analysis For Therapeutic Response Assessment Using Dynamic Contrast‐Enhanced MRI
Authors: Wang C , Subashi E , Liang X , Yin F , Chang Z 
Published: July 2016

Purpose:To compare the performance of shutter‐speed(SS) model with transcytolemmal water exchange analysis against the Tofts model in the study of the efficacy of an anti‐angiogenesis drugMethods:16 mice with LS‐174T implanted were randomly assigned into treatment/control groups (n=8/group) and received bevacizumab/saline three times (Day1/Day4/Day8). All mice received one pre‐ (Day0) and two post‐treatment (Day2/Day9) DCE scans. For each scan, the CA extravasation rate constant KTtrans/KStrans from the Tofts/SS model were calculated. The intracellular water residence time τi which reflects limited transcytolemmal water exchange between cell and extravascular‐extracellular‐space were also analyzed using SS model. A biological subvolume(BV) within the tumor was automatically segmented based on the τi intensity distribution, and the SS model parameters within the BV (KS,BVtrans and τi, BV) were analyzed. Rank‐sum tests were conducted to assess the differences of each parameter's statistics (mean value/coefficient‐of‐variation (CV) /kurtosis/skewness/heterogeneity indices d1 and d2) between treatment/control groups. Experiment using support vector machine in a leave‐one‐out approach were performed to validate the use of the analyzed biomarkers for treatment/control classification.Results:The SS model was a better fit for all scans in terms of Bayesian information criterion. At Day9, the treatment group had significantly higher mean KTtrans(p=0.021), KStrans(p=0.021) and τi(p=0.045). In the identified BV, the treatment group had significantly higher mean KS,BVtrans at both Day2(p=0.038) and Day9(p=0.007). Additionally, at Day9, the treatment group had significantly higher mean τi, BV(p=0.045) and higher KS,BVtrans heterogeneity indices d1(p=0.010) and d2(p=0.021) values. When using KS,BVtrans statistics for treatment/control group classification, the highest accuracy was 68.8%/87.5% at Day2/Day9; this result was better than the result of 62.5%/87.5% using KStrans statistics and 50.0%/87.5% using KTtrans statistics.Conclusion:The SS model parameters may be more reliable than the Tofts model parameters for therapeutic assessment. The proposed biological subvolume in this work may be useful for early therapeutic effect monitoring.
SU‐F‐J‐159: Influence of the Elevated Posterior Position by Using the Customized Vacuum‐Bag On the Abdominal MR Image Quality: A Quantitative Phantom Study
Authors: Wong O , Yuan J , Law M , Ding A , Yu S , Cheung K 
Published: July 2016

Purpose:Signal‐to‐noise ratio(SNR) of MR abdominal imaging in diagnostic radiology is maximized by minimizing the coil‐to‐patient distance. However, for radiotherapy applications, customized vacuum‐bag is needed for abdominal immobilization at the cost of the increasing distance to the posterior spine coil. This sub‐optimized coil setting for RT applications may compromise image quality, such as SNR and homogeneity, thus potentially affect tissue delineation. In this study, we quantitatively evaluate the effect of the vertical position change on SNR and image quality change using an ACR MR phantom.Methods:An ACR MR phantom was placed on the flat couch top. Images were acquired using an 18‐channel body array coil and spine coil on a dedicated 1.5T MR‐simulator. The scan was repeated three times with the ACR phantom elevated up to 7.5cm from the couch top, with a step size of 2.5cm. All images were acquired using standard ACR test sequence protocol of 2D spin‐echo T1‐weighted(TR/TE=500/200ms) and T2‐weighted(TR/TE1/TE2=2000/20/80) sequences. For all scans, pre‐scan normalization was turned on, and the distance between the phantom and the anterior 18‐channel body array coil was kept constant. SNR was calculated using the slice with a large water‐only region of the phantom. Percent intensity uniformity(PIU) and low contrast object detectability(LCD) were assessed by following ACR test guidelines.Results:The decrease in image SNR(from 335.8 to 169.3) and LCD(T1: from 31 to 19 spokes, T2: 26 to 16 spokes) were observed with increasing vertical distance. After elevating the phantom by 2.5cm(approximately the thickness of standard vacuum‐bag), SNR change(from 335.8 to 275.5) and LCD(T1: 31 to 26 spokes, T2: 26 to 21 spokes) change were noted. However, similar PIU was obtained for all choices of vertical distance (T1: 94.5%–95.0%, T2: 94.4%–96.8%).Conclusion:After elevating the scan object, reduction in SNR level and contrast detectability but no change in image homogeneity was observed.
SU‐F‐J‐170: Comparison of Residual Distortions for MRI Sequences On a 3T MRI Unit Using a 3D Rectilinear Grid Phantom
Authors: Diaz Molina F , Cao Y , Klein E , Knisely J , Gill G , Marrero M , Schulder M , Kirsch J 
Published: July 2016

Purpose:Gamma Knife (GK) planning is mostly based upon MRI. Due to the high accuracy required for SRS treatments, geometric distortions in these images should be minimal. MRI Manufacturer provided first order geometric distortions correction algorithms may not reduce distortions to a level that may not be acceptable for treatments requiring high positional accuracy. The purpose of this work is to evaluate the residual, radiosurgery‐relevant geometric distortions on VIBE, MPRAGE, GRE and CISS sequences.Methods:The 3D rectilinear phantom, GRID3D, was scanned in the Leksell Frame‐G with different MRI axial sequences: MPRAGE, VIBE, GRE and CISS, on a Siemens SKYRA 3T MR unit. Siemens 3D distortion correction was applied to all sequences. The residual distortion map of the phantom's 2002 vertices was evaluated by comparing the expected positions of the vertices, with the actual measured locations using Modus’ image distortion analysis software (QUASARTM). Distortions were specified as X, Y, Z, and radial deviations. As an independent verification, the MRI sequences were co‐registered with CT images of the phantom in GammaPlan.Results:All sequences showed mean radial residual distortions greater than 1 mm. Maximum radial distortion ranged between 3 and 8 mm. Z axis distortions were the highest for GRE and CISS sequences, and lowest for VIBE. Y distortions were lowest for the VIBE and MPRAGE sequences. X distortion was lowest for GRE and CISS sequences. Almost equal X and Y distortions were measured for CISS. Larger distortions were mainly observed in peripheral regions of the phantom for all sequences. CT‐MR co‐registration in GammaPlan confirmed these results. The residual distortions were deemed unacceptable for MR based GK treatments.Conclusion:The in‐phantom analysis of MR sequences using the Modus phantom allows for effective quantitative evaluation of residual distortion in MR images. MR‐CT co‐registration facilitates qualitative assessment of MRI distortions.
SU‐F‐J‐172: Hybrid MR/CT Compatible Phantom for MR‐Only Based Radiotherapy
Authors: Kim M , Lee S , Song K , Park S , Suh T 
Published: July 2016

Purpose:Development of hybrid MR/CT compatible phantom was introduced to fully establish MR image only radiation treatment and this suggested technique using in‐house developed hybrid MR/CT compatible phantom image would utilize to generate radiation treatment planning and perform dose calculation without multi‐modal registration process or generation of pseudo CT.Methods:Fundamental characteristics for “hybrid MR/CT compatible phantom” was established: Relaxation times equivalent to human tissue, dielectric properties, homogeneous relaxation times, sufficient strength to fabricate a torso, ease of handling, a wide variety of density material for calibration, chemical and physical stability over an extended time. For this requirements, chemical component in each tested plug which would be tissue equivalent to human tissue on MR and CT image and production of phantom body and plug was performed. Chemical component has described below: Agaros, GdCl3, NaN3, NaCl, K2Co3, deionized‐distilled water. Various mixture of chemical component to simulate human tissue on both MR and CT image was tested by measuring T1, T2 relaxation time and signal intensity (SI) on MR image and Hounsfield unit (HU) on CT and each value was compared. The hybrid MR/CT compatible phantom with 14 plugs was designed and has made. Total height and external diameter was decided by internal size of 32 channel MR head‐coil.Results:Tissue‐equivalent chemical component materials and hybrid MR/CT compatible phantom was developed. The range of T1, T2 relaxation time and SI on MR image, HU on CT was acquired and could be adjusted to correspond to simulated human tissue.Conclusion:Current result shows its possibility for MR‐only based radiotherapy and the best mixing rate of chemical component for tissue‐equivalent image on MR and CT was founded. However, additional technical issues remain to be overcome. Conversion of SI on MR image into HU and dose calculation based on converted MRI will be progressing.
SU‐F‐J‐181: An Alternative Patient Alignment Tool On TomoTherapy: The First In‐ Human Megavoltage‐Topogram Acquisition
Authors: Yang L , Low D , Lee P , Ruan D , Chin R , Kaprealian T , Kamrava M , Kupelian P , Beron P , Steinberg M , Chen A , Agazaryan N , Ray S , Qi X 
Published: July 2016

Purpose:To show the first in‐human Megavoltage (MV)‐Topogram acquisition for the evaluation of the potential for MV‐Topogram‐based alignment as an alternative to MVCT for reducing dose and imaging time.Methods:A lung cancer patient was enrolled in an ongoing IRB‐approved clinical trial at our institute. The patient was set up using the clinical protocol employing positioning lasers. 3.2mm diameter tungsten spheres were placed on the patient's skin at their alignment tattoos to check surface‐based marker concordance between topograms and MVCT. Anterior‐Posterior (AP) and lateral (LAT) MV‐Topograms were acquired using gantry angles of 0°/90° with a 1mm collimator opening, all MLC leafs open, 4cm/s couch speed, and 12.5s scanning time. The topogram acquisition was immediately followed by the normal MVCT scan acquisition. MV‐Topograms were reconstructed from the detector exit‐data using in‐house developed software. The topograms were also enhanced using contrast‐limited adaptive histogram equalization (CLAHE). The MV‐Topograms were registered to reference kV‐based digitally reconstructed topograms. The localization results were compared against results obtained comparing the clinical MVCT to the kVCT simulation.Results:The shifts using the unenhanced Topograms, enhanced Topograms, and MVCT were (LAT, LONG, VERT, ROLL) (5.8mm, 2.6mm, −5.6mm, 0.34°), (3.9mm, 2.5mm, −2.2mm, 0.65°) and (2.4mm, 1.5mm, −3.0mm, 0.5°), respectively. The magnitude alignment differences between the enhanced Topograms and MVCT were within 1.5 mm and 0.15°. The average MVCT and total Topogram acquisition times were 272.9s ± 31.5s and 46s, respectively.Conclusion:MV‐Topograms have the potential for providing equivalent performance with less dose and acquisition time than the traditional MVCT technique. We are evaluating other sites as well as adding patients to develop statistically significant analyses regarding the alignment quality differences. MV‐Topograms are likely to be most clinically useful for bony anatomy and radiopaque marker‐based alignments.The study was supported by an Accuray Grant.
SU‐F‐J‐183: Interior Region‐Of‐Interest Tomography by Using Inverse Geometry System
Authors: Kim K , Kim D , Kang S , Kim T , Shin D , Cho M , Noh Y , Suh T 
Published: July 2016

Purpose:The inverse geometry computed tomography (IGCT) composed of multiple source and small size detector has several merits such as reduction of scatter effect and large volumetric imaging within one rotation without cone‐beam artifact, compared to conventional cone‐beam computed tomography (CBCT). By using this multi‐source characteristics, we intend to present a selective and multiple interior region‐of‐interest (ROI) imaging method by using a designed source on‐off sequence of IGCT.Methods:All of the IGCT sources are operated one by one sequentially, and each projection in the shape of narrow cone‐beam covers its own partial volume of full field of view (FOV) determined from system geometry. Thus, through controlling multi source operation, limited irradiation within ROI is possible and selective radon space data for ROI imaging can be acquired without additional X‐ray filtration. With this feature, we designed a source on‐off sequence for multi ROI‐IGCT imaging, and projections of ROI‐IGCT were generated by using the on‐off sequence. Multi ROI‐IGCT images were reconstructed by using filtered back‐projection algorithm. All these imaging process of our study has been performed by utilizing digital phantom and patient CT data. ROI‐IGCT images of the phantom were compared to CBCT image and the phantom data for the image quality evaluation.Results:Image quality of ROI‐IGCT was comparable to that of CBCT. However, the distal axial‐plane from the FOV center, large cone‐angle region, ROI‐IGCT showed uniform image quality without significant cone‐beam artifact contrary to CBCT.Conclusion:ROI‐IGCT showed comparable image quality and has the capability to provide multi ROI image within a rotation. Projection of ROI‐IGCT is performed by selective irradiation, hence unnecessary imaging dose to non‐interest region can be reduced. In this regard, it seems to be useful for diagnostic or image guidance purpose in radiotherapy such as low dose target localization and patient alignment.This research was supported by the Mid‐career Researcher Program through NRF funded by the Ministry of Science, ICT & Future Planning of Korea (NRF‐2014R1A2A1A10050270) and by the Radiation Technology R&D program through the National Research Foundation of Korea funded by the Ministry of Science, ICT & Future Planning (No. 2013M2A2A7038291)
SU‐F‐J‐186: Enabling Adaptive IMPT with CBCT‐Based Dose Recalculation for H&N and Prostate Cancer Patients
Authors: Kurz C , Park Y , Kamp F , Rit S , Winey B , Sharp G , Reiner M , Nijhuis R , Hansen D , Ganswindt U , Thieke C , Belka C , Parodi K , Landry G 
Published: July 2016

Purpose:To enable adaptive intensity modulated proton therapy for sites sensitive to inter‐fractional changes on the basis of accurate CBCT‐based proton dose calculations. To this aim two CBCT intensity correction methods are considered: planning CT (pCT) to CBCT DIR and projection correction based on pCT DIR prior.Methods:3 H&N and 3 prostate cancer patients with CBCT images and corresponding projections were used in this study, in addition to pCT and re‐planning CT (rpCT) images (H&N only). A virtual CT (vCT) was generated by pCT to CBCT DIR. In a second approach, the vCT was used as prior for scatter correction of the CBCT projections to yield a CBCTcor image. BEV 2D range maps of SFUD IMPT plans were compared. For the prostate cases, the geometric accuracy of the vCT was also evaluated by contour comparison to physician delineation of the CBCTcor and original CBCT.Results:SFUD dose calculations on vCT and CBCTcor were found to be within 3mm for 97% to 99% of 2D range maps. Median range differences compared to rpCT were below 0.5mm. Analysis showed that the DIR‐based vCT approach exhibits inaccuracies in the pelvic region due to the very low soft‐tissue contrast in the CBCT. The CBCTcor approach yielded results closer to the original CBCT in terms of DICE coefficients than the vCT (median 0.91 vs 0.81) for targets and OARs. In general, the CBCTcor approach was less affected by inaccuracies of the DIR used during the generation of the vCT prior.Conclusion:Both techniques yield 3D CBCT images with intensities equivalent to diagnostic CT and appear suitable for IMPT dose calculation for most sites. For H&N cases, no considerable differences between the two techniques were found, while improved results of the CBCTcor were observed for pelvic cases due to the reduced sensitivity to registration inaccuracies.Deutsche Forschungsgemeinschaft (MAP); Bundesministerium fur Bildung und Forschung (01IB13001)