bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐E‐J‐66: Evaluation of a Real‐Time Positioning Assistance Simulator System for Skull Radiography Using the Microsoft Kinect
Authors: Kurata T , Ono M , Kozono K , Fukuyoshi R , Sato S , Toyofuku F 
Published: July 2014

Purpose:The purpose of this study is to investigate the feasibility of a low cost, small size positioning assistance simulator system for skull radiography using the Microsoft Kinect sensor. A conventional radiographic simulator system can only measure the three‐dimensional coordinates of an x‐ray tube using angle sensors, but not measure the movement of the subject. Therefore, in this study, we developed a real‐time simulator system using the Microsoft Kinect to measure both the x‐ray tube and the subject, and evaluated its accuracy and feasibility by comparing the simulated and the measured x‐ray images.Methods:This system can track a head phantom by using Face Tracking, which is one of the functions of the Kinect. The relative relationship between the Kinect and the head phantom was measured and the projection image was calculated by using the ray casting method, and by using three‐dimensional CT head data with 220 slices at 512 × 512 pixels. X‐ray images were thus obtained by using a computed radiography (CR) system. We could then compare the simulated projection images with the measured x‐ray images from 0 degrees to 45 degrees at increments of 15 degrees by calculating the cross correlation coefficient C.Results:The calculation time of the simulated projection images was almost real‐time (within 1 second) by using the Graphics Processing Unit(GPU). The cross‐correlation coefficients C are: 0.916; 0.909; 0.891; and, 0.886 at 0, 15, 30, and 45 degrees, respectively. As a result, there were strong correlations between the simulated and measured images.Conclusion:This system can be used to perform head positioning more easily and accurately. It is expected that this system will be useful for learning radiographic techniques by students. Moreover, it could also be used for predicting the actual x‐ray image prior to x‐ray exposure in clinical environments.
SU‐E‐J‐69: Evaluation of the Lens Dose On the Cone Beam IGRT Procedures
Authors: Palomo‐Llinares R , Pujades M , Gimeno‐Olmos J , Carmona Meseguer V , Lliso‐Valverde F , Candela‐Juan C , Ballester F , Perez‐Calatayud J 
Published: July 2014

Purpose:With the establishment of the IGRT as a standard technique, the extra dose that is given to the patients should be taken into account. Furthermore, it has been a recent decrease of the dose threshold in the lens, reduced to 0.5 Gy (ICRP ref 4825‐3093‐1464 on 21st April, 2011). The purpose of this work was to evaluate the extra dose that the lens is receive due to the Cone‐Beam (CBCT) location systems in Head‐and‐Neck treatments.Methods:The On‐Board Imaging (OBI) v 1.5 of the two Varian accelerators, one Clinac iX and one True Beam, were used to obtain the dose that this OBI version give to the lens in the Head‐and‐Neck location treatments. All CBCT scans were acquired with the Standard Dose Head protocol (100 kVp, 80 mA, 8 ms and 200 degree of rotation). The measurements were taken with thermoluminescence (TLD) EXTRAD (Harshaw) dosimeters placed in an anthropomorphic phantom over the eye and under 3 mm of bolus material to mimic the lens position. The center of the head was placed at the isocenter. To reduce TLD energy dependence, they were calibrated at the used beam quality.Results:The average lens dose at the lens in the OBI v 1.5 systems of the Clinac iX and the True Beam is 0.071 and 0.076 cGy/CBCT, respectively.Conclusions:The extra absorbed doses that receive the eye lenses due to one CBCT acquisition with the studied protocol is far below the new ICRP recommended threshold for the lens. However, the addition effect of several CBCT acquisition during the whole treatment should be taken into account.
SU‐E‐J‐71: Feasibility Study On MRI‐Based BANG3 Gel Dosimetry Using Dual‐Source Parallel RF Transmission System
Authors: Kim S , Baek H , Lee J , Lee D , Lee S , Choe B 
Published: July 2014

Purpose:In this work, we present the feasibility of use of the parallel RF transmission with multiple RF source (MultiTransmit) imaging in MRI‐based polymer gel dosimetry.Methods:The commercially available BANG3 gel was used for gel dosimetry. Spin‐spin relaxation rate R2 was used to quantify the absorbed dose. The image quality (signal‐to‐noise ratio, SNR; image uniformity) and B1 field inhomogeneity between conventional single‐source and MultiTransmit MR imaging were compared. Finally, the estimated R2 uncertainty σ(R2) and dosimetric performance (i.e., dose resolution) between conventional single‐source and MultiTransmit MR imaging were compared.Results:Image quality and B1 field homogeneity within each calibration vial and large phantom was statistically better in MultiTransmit imaging than in conventional single‐source RF transmission imaging (P < 0.005 for all calibration vials). In particular, σ(R2) (defined as the standard uncertainty of R2) was lower on the MultiTransmit images than on the conventional single‐source images. Furthermore, the MultiTransmit measurement gives a lower than that obtained using the conventional single‐source method.Conclusion:The improved image quality and B1 homogeneity resulted in reduced dose uncertainty (i.e., σ(R2) and dose resolution) in MRI‐based polymer gel dosimetry, suggesting that MultiTransmit MR imaging has potential benefits for use in clinical 3D gel dosimetry without the need for the complicated B1 field correction method.
SU‐E‐J‐74: Impact of Respiration‐Correlated Image Quality On Tumor Motion Reconstruction in 4D‐CBCT: A Phantom Study
Authors: Lee S , Lu B , Samant S 
Published: July 2014

Purpose:To investigate the effects of scanning parameters and respiratory patterns on the image quality for 4‐dimensional cone‐beam computed tomography(4D‐CBCT) imaging, and assess the accuracy of computed tumor trajectory for lung imaging using registration of phased 4D‐CBCT imaging with treatment planning‐CT.Methods:We simulated a periodic and non‐sinusoidal respirations with various breathing periods and amplitudes using a respiratory phantom(Quasar, Modus Medical Devices Inc) to acquire respiration‐correlated 4D‐CBCT images. 4D‐CBCT scans(Elekta Oncology Systems Ltd) were performed with different scanning parameters for collimation size(e.g., small and medium field‐of‐views) and scanning speed(e.g., slow 50°·min−1, fast 100°·min−1). Using a standard CBCT‐QA phantom(Catphan500, The Phantom Laboratory), the image qualities of all phases in 4D‐CBCT were evaluated with contrast‐to‐noise ratio(CNR) for lung tissue and uniformity in each module. Using a respiratory phantom, the target imaging in 4D‐CBCT was compared to 3D‐CBCT target image. The target trajectory from 10‐respiratory phases in 4D‐CBCT was extracted using an automatic image registration and subsequently assessed the accuracy by comparing with actual motion of the target.Results:Image analysis indicated that a short respiration with a small amplitude resulted in superior CNR and uniformity. Smaller variation of CNR and uniformity was present amongst different respiratory phases. The small field‐of‐view with a partial scan using slow scan can improve CNR, but degraded uniformity. Large amplitude of respiration can degrade image quality. RMS of voxel densities in tumor area of 4D‐CBCT images between sinusoidal and non‐sinusoidal motion exhibited no significant difference. The maximum displacement errors of motion trajectories were less than 1.0 mm and 13.5 mm, for sinusoidal and non‐sinusoidal breathings, respectively. The accuracy of motion reconstruction showed good overall agreement with the 4D‐CBCT image quality results only using sinusoidal breathings.Conclusion:This information can be used to determine the appropriate acquisition parameters of 4D‐CBCT imaging for registration accuracy and target trajectory measurements in a clinical setting.
SU‐E‐J‐76: Incorporation of Ultrasound Elastography in Target Volume Delineation for Partial Breast Radiotherapy Planning: A Comparative Study
Authors: Juneja P , Harris E , Bamber J 
Published: July 2014

Purpose:There is substantial observer variability in the delineation of target volumes for post‐surgical partial breast radiotherapy because the tumour bed has poor x‐ray contrast. This variability may result in substantial variations in planned dose distribution. Ultrasound elastography (USE) has an ability to detect mechanical discontinuities and therefore, the potential to image the scar and distortion in breast tissue architecture. The goal of this study was to compare USE techniques: strain elastography (SE), shear wave elastography (SWE) and acoustic radiation force impulse (ARFI) imaging using phantoms that simulate features of the tumour bed, for the purpose of incorporating USE in breast radiotherapy planning.Methods:Three gelatine‐based phantoms (10% w/v) containing: a stiff inclusion (gelatine 16% w/v) with adhered boundaries, a stiff inclusion (gelatine 16% w/v) with mobile boundaries and fluid cavity inclusion (to mimic seroma), were constructed and used to investigate the USE techniques. The accuracy of the elastography techniques was quantified by comparing the imaged inclusion with the modelled ground‐truth using the Dice similarity coefficient (DSC). For two regions of interest (ROI), the DSC measures their spatial overlap. Ground‐truth ROIs were modelled using geometrical measurements from B‐mode images.Results:The phantoms simulating stiff scar tissue with adhered and mobile boundaries and seroma were successfully developed and imaged using SE and SWE. The edges of the stiff inclusions were more clearly visible in SE than in SWE. Subsequently, for all these phantoms the measured DSCs were found to be higher for SE (DSCs: 0.91–0.97) than SWE (DSCs: 0.68–0.79) with an average relative difference of 23%. In the case of seroma phantom, DSC values for SE and SWE were similar.Conclusion:This study presents a first attempt to identify the most suitable elastography technique for use in breast radiotherapy planning. Further analysis will include comparison of ARFI with SE and SWE.This work is supported by the EPSRC Platform Grant, reference number EP/H046526/1.
SU‐E‐J‐77: Inter‐Fractional Variations in Internal Tumor Volumes Using Multiple 4DCTs and CBCTs
Authors: Xue M , Feigenberg S , Tan S , Reese A , Yi B , D' Souza W , Lu W 
Published: July 2014

Purpose:To quantitatively evaluate the inter‐fractional variations in ITVs over the course of treatment using multiple 4DCTs and CBCTs for patients treated with SBRT for lung targets. To compare using ITV generated from all phases of a 4D or average intensity projection (ITV‐AIP) as reference contours for image guidance.Methods:An IRB approved study included five patients who received SBRT for a lung target using daily image guidance with a CBCT. Three 4DCTs were acquired before (simulation), during and at the end of treatment. ITV‐4Ds (on all 10 phases) and ITV‐CBCTs were contoured manually. All CT images and contours were registered to the reference image – AIP1 from 4D1. The registration consists of intensity‐based image registration followed by manual soft‐tissue alignment, where physicians manually make shift to ensure that the tumor seen on CBCT is encompassed in ITV‐4D1 or ITV‐AIP1. The relationship between two ITVs was quantified by centroid distance, volume inclusion, and volume overlap (Dice Coefficient).Results:The average volume for ITV‐4D, ITV‐AIP, and ITV‐CBCT were 23.1, 17.2, and 14.1 cm3, respectively. When using ITV‐4D1 as a reference contour in the manual soft‐tissue alignment, an average of 93% of ITV‐CBCTs was included in ITV‐4D1, with a centroid distance of 2.0 mm. Only 81% of ITV‐4Ds were included in ITV‐4D1. The Dice Coefficient between ITV‐4D1 and ITV‐4Ds was only 0.68, suggesting that the two ITVs were not highly overlapping. For all comparisons, the results were similar using either ITV‐AIP1 or ITV‐4D1 as a reference contour in the manual soft‐tissue alignment.Conclusions:There were noteworthy inter‐fractional variations in ITV‐4Ds. Compared to ITV‐4D, ITV‐AIP was much similar to ITV‐CBCT. However, there was no significant difference between using ITV‐4D1 and using ITV‐AIP1 as a reference contour for image guidance. Further dosimetric studies are required to evaluate actual tumor coverage.This study was supported in part by Philips Healthcare.
SU‐E‐J‐81: Interplay Effect in Non‐Gated Dynamic Treatment Delivery of a Lung Phantom with Simulated Respiratory Motion
Authors: Desai V , Fagerstrom J , Bayliss A , Kissick M 
Published: July 2014

Purpose:To quantify the interplay effect in non‐gated VMAT external beam delivery using realistic, clinically relevant 3D motion in an anthropomorphic lung phantom, and to determine if adding margins is sufficient to account for motion or if gating is required in all cases.Methods:A 4D motion stage was used to move a Virtual Water (VW) lung target containing a piece of radiochromic EBT3 film in an anthropomorphic chest phantom. A five‐arc stereotactic body radiation therapy (SBRT) treatment was planned using a CT scan of the phantom in its stationary position, using planning parameters chosen to push the optimizer to achieve a highly‐modulated plan. Two scenarios were delivered using a Varian TrueBeam: the first was delivered with the phantom and target both stationary and the second was delivered with the phantom stationary but the target moving in a realistic, irregular 3D elliptical pattern. A single piece of 4×4 cm2 film was used per fraction, located in the central coronal plane of the target. Film was calibrated on a 6 MV beam with dose values from 0.20 to 20 Gy.Results:Preliminary test films were analyzed in ImageJ and MatLab software. Dose maps were calculated on a central region of interest (ROI) delineated on both the motion‐induced and stationary films. Both static and dynamic film dose maps agreed with planning values within acceptable uncertainty.Conclusion:Including a large number of arcs in a clinically realistic SBRT treatment could reduce the effect of motion interplay due to averaging. Because all clinics do not employ multiple arcs for SBRT lung treatments, it is still important to consider the effects of motion on treatment delivery. Further analysis on the treatment films, as well as a broader investigation other planning parameters, will be conducted.
SU‐E‐J‐87: Lung Deformable Image Registration Using Surface Mesh Deformation for Dose Distribution Combination
Authors: Labine A , Chav R , Carrier J , DeGuise J , Bedwani S 
Published: July 2014

Purpose:To allow a reliable deformable image registration (DIR) method for dose calculation in radiation therapy. This work proposes a performance assessment of a morphological segmentation algorithm that generates a deformation field from lung surface displacements with 4DCT datasets.Methods:From the 4DCT scans of 15 selected patients, the deep exhale phase of the breathing cycle is identified as the reference scan. Varian TPS EclipseTM is used to draw lung contours, which are given as input to the morphological segmentation algorithm. Voxelized contours are smoothed by a Gaussian filter and then transformed into a surface mesh representation. Such mesh is adapted by rigid and elastic deformations to match each subsequent lung volumes. The segmentation efficiency is assessed by comparing the segmented lung contour and the TPS contour considering two volume metrics, defined as Volumetric Overlap Error (VOE) [%] and Relative Volume Difference (RVD) [%] and three surface metrics, defined as Average Symmetric Surface Distance (ASSD) [mm], Root Mean Square Symmetric Surface Distance (RMSSD) [mm] and Maximum Symmetric Surface Distance (MSSD) [mm]. Then, the surface deformation between two breathing phases is determined by the displacement of corresponding vertices in each deformed surface. The lung surface deformation is linearly propagated in the lung volume to generate 3D deformation fields for each breathing phase.Results:The metrics were averaged over the 15 patients and calculated with the same segmentation parameters. The volume metrics obtained are a VOE of 5.2% and a RVD of 2.6%. The surface metrics computed are an ASSD of 0.5 mm, a RMSSD of 0.8 mm and a MSSD of 6.9 mm.Conclusion:This study shows that the morphological segmentation algorithm can provide an automatic method to capture an organ motion from 4DCT scans and translate it into a volume deformation grid needed by DIR method for dose distribution combination.
SU‐E‐J‐88: Margin Reduction of Level II/III Planning Target Volume for Image‐Guided Simultaneous Integrated Boost Head‐And‐Neck Treatment
Authors: Can S , Neylon J , Qi S , Santhanam A , Low D 
Published: July 2014

Purpose:To investigate the feasibility of improved normal tissue sparing for head‐and‐neck (H' N) image‐guided radiotherapy (IGRT) by employing tighter CTV‐to‐PTV margins for target level II/III though a GPU‐based deformable image registration and dose accumulation framework.Methods:Ten H' N simultaneous integrated boost cases treated on TomoTherapy were retrospectively analyzed. Weekly kVCT scans in addition to daily MVCT scans were acquired for each patient. Reduced margin plans were generated with 0‐ mm margin for level II and III PTV (while 3‐5 mm margin for PTV1) and compared with the standard margin plan using 3‐5mm margin to all CTV1‐3 (reference plan). An in‐house developed GPU‐based 3D image deformation tool was used to register and deform the weekly KVCTs with the planning CT and determine the delivered mean/minimum/maximum dose, dose volume histograms (DVHs), etc.Results:Compared with the reference plans, the averaged cord maximum, the right and left parotid doses reduced by 22.7 %, 16.5 %, and 9 % respectively in the reduced margin plans. The V95 for PTV2 and PTV3 were found within 2 and 5% between the reference and tighter margin plans. For the reduced margin plans, the averaged cumulative mean doses were consistent with the planned dose for PTV1, PTV2 and PTV3 within 1.5%, 1.7% and 1.4%. Similar dose variations of the delivered dose were seen for the reference and tighter margin plans. The delivered maximum and mean doses for the cord were 3.55 % and 2.37% higher than the planned doses; a 5 % higher cumulative mean dose for the parotids was also observed for the delivered dose than the planned doses in both plans.Conclusion:By imposing tighter CTV‐to‐PTV margins for level II and III targets for H' N irradiation, acceptable cumulative doses were achievable when coupled with weekly kVCT guidance while improving normal structure sparing.
SU‐E‐J‐90: MRI‐Based Treatment Simulation and Patient Setup for Radiation Therapy of Brain Cancer
Authors: Yang Y , Cao M , Han F , Santhanam A , Neylon J , Gomez C , Kaprealian T , Sheng K , Agazaryan N , Low D , Hu P 
Published: July 2014

Purpose:Traditional radiation therapy of cancer is heavily dependent on CT. CT provides excellent depiction of the bones but lacks good soft tissue contrast, which makes contouring difficult. Often, MRIs are fused with CT to take advantage of its superior soft tissue contrast. Such an approach has drawbacks. It is desirable to perform treatment simulation entirely based on MRI. To achieve MR‐based simulation for radiation therapy, bone imaging is an important challenge because of the low MR signal intensity from bone due to its ultra‐short T2 and T1, which presents difficulty for both dose calculation and patient setup in terms of digitally reconstructed radiograph (DRR) generation. Current solutions will either require manual bone contouring or multiple MR scans. We present a technique to generate DRR using MRI with an Ultra Short Echo Time (UTE) sequence which is applicable to both OBI and ExacTrac 2D patient setup.Methods:Seven brain cancer patients were scanned at 1.5 Tesla using a radial UTE sequence. The sequence acquires two images at two different echo times. The two images were processed using in‐house software. The resultant bone images were subsequently loaded into commercial systems to generate DRRs. Simulation and patient clinical on‐board images were used to evaluate 2D patient setup with MRI‐DRRs.Results:The majority bones are well visualized in all patients. The fused image of patient CT with the MR bone image demonstrates the accuracy of automatic bone identification using our technique. The generated DRR is of good quality. Accuracy of 2D patient setup by using MRI‐DRR is comparable to CT‐based 2D patient setup.Conclusion:This study shows the potential of DRR generation with single MR sequence. Further work will be needed on MR sequence development and post‐processing procedure to achieve robust MR bone imaging for other human sites in addition to brain.
SU‐E‐J‐91: Novel Epitaxial Silicon Array for Quality Assurance in Photon and Proton Therapy
Authors: Talamonti C , Menichelli D , Zani M , Friedl F , Scaringella M , Bruzzi M , Bucciolini M 
Published: July 2014

Purpose:to demonstrate suitability of a novel silicon array for measuring the dose properties of highly conformal photon and proton beams.Methods:prototype under test is a 24cm long linear array prototype, although the underlying technology is suitable to construct 2D arrays as well. It is based on a 64pixels monolithic sensor with 1mm pixel pitch, made of epitaxial ptype silicon. Thanks to design modularity, more sensors can be placed side by side without breaking pixel pitch. Flattened and unflattened photon beams, as well as proton radiation from a cyclotron in pencil beam scanning mode, were considered. Measurements of beam characteristics as percentage depth doses, dose profiles, output factors and energy response, which are necessary to deliver radiation with high precision and reliability, were performed.Results:Dose rate independence with photons was verified in the dose per pulse range 0.03 to 2mGy. Results clearly indicate nondependence of the detector sensitivity both for flattened and unflattened beams, with a variation of at most 0.5percentage. OFs were obtained for field with a lateral size ranging from 0.8cm to 16cm and the results are in good agreement with ion chamber A1SL, max difference less than 1.5percentage. Field sizes and beam penumbra were measured and compared to EBT film results. Concerning proton beams, sensitivity independence on dose rate was verified by changing the beam current in the interval 2‐130Gy/s. Field sizes and beam penumbra measurements are in agreement with data taken with a scintillating 2D array with 0.5mm resolution IBA Lynx, and a better penumbra definition than an array of ionization chambers IBA MatriXX is reached.Conclusion:The device is a novel and valuable tool for QA both for photon and proton dose delivery. All measurements demonstrated its capability to measure with high spatial resolution many crucial properties of the RT beam.