T Suh

Development of a deformable lung phantom for the evaluation of deformable registration

A deformable lung phantom was developed to simulate patient breathing motion and to evaluate a deformable image registration algorithm. The phantom consisted of an acryl cylinder filled with water and a latex balloon located in the inner space of the cylinder. A silicon membrane was attached to the inferior end of the phantom. The silicon membrane was designed to simulate a real lung diaphragm and to reduce motor workload. This specific design was able to reduce the use of metal, which may prevent infrared sensing of the real position management (RPM) gating system for four‐dimensional (4D) CT image acquisition. Verification of intensity based three‐dimensional (3D) demons deformable registration was based on the peak exhale and peak inhale breathing phases. The registration differences ranged from 0.60 mm to 1.11 mm and accuracy was determined according to inner target deformation. The phantom was able to simulate features and deformation of a real human lung and has the potential for wide application for 4D radiation treatment planning. PACS number: 87.57.Gg

SU‐FF‐T‐476: Dose‐Sparing Effects of a Rectal Balloon in Proton Therapy of the Prostate

Purpose; The normal organ (bladder, rectum) sparing is very important for radiation therapy of the pelivis. Many people are studying with the effort for rectal and bladder spearing, however the actual circumstances to are satisfied which can not find the method. In this study, the decrease used the balloon to order the rectal dose. The aim of the study was to investigate the dose volume effects of a water‐filled rectal balloon in the rectum. Materials and Methods; We inserted the balloon(100cc water filled, 10cm length, 3cm diameter) in rectum for 10 proton therapy patients with prostate cancers. The systems were loaded with Eclipse proton planning system(Ver. 7.5) and Two sets of CTimages before and after ballooning were acquired. Rectum and bladder volumes were delineated on 3‐mm‐thick CTimages. A comparison between dose volume histogram(DVH) with and without balloon in rectum for proton therapy of the prostate cancers.Results; More organ and target volume changes with shape because inserted the balloon in rectum. Mean dose of rectal difference between with and without balloon was about 20%, because volume of rectum escape from a radiation area due to the balloon. Mean dose of bladder difference between with and without balloon was about 6%. Conclusion; The rectal ballon is very useful for bladder and rectal sparing with proton therapy of the prostate cancers. This research is believed to be sufficiently accurate and clinically useful.

SU-GG-I-23: A Comparison of Adaptive Radiotherapy Treatment Planning Between Planning CT and KVCBCT

Purpose: The recent integration of kilo‐voltage cone beam computed tomography (kV‐CBCT) imaging systems into linear accelerators makes it possible to image and treat a patient on a single machine. The goal of this study is to investigate the feasibility and usefulness of acquiring kV‐CBCT for adaptive radiotherapy for patients with lung and phantom study with significant target position. Method and Materials: A self made brain phantom and quality assurance phantom were used to compare the dosimetric and geometric accuracy between planning CT and kV‐CBCT with bow‐tie filter added. The quality of the kV‐CBCT volume images acquired using phantom was evaluated by measuring the spatial accuracy, contrast, hounsfield units (HU), and converting HU to electron density. The kV‐CBCT was registered to the CTimage using normalized mutual information. Results: In both phantom studies, the DVH based on kV‐CBCT images were in excellent agreement with DVH based on planning CTimages.CBCTimages were dependent on image uniformity, linearity and it needed verify the difference the mean HU value of the center ROI and peripheral ROI using histogram. The difference (<1%) is found in the calculated dose to the target for a complex inhomogeneous phantom between using kV‐CBCT images and planning CTimages. These results indicate that kV‐CBCT images can be used to calculate dosimetric parameter accurately in radiotherapytreatment planning. In a patient study, doses for targets volume plans calculated on kV‐CBCT images agreed within 5% with those calculated on planning CT.Conclusion: We have investigated the feasibility and usefulness of acquiring on‐board kV‐CBCT images for adaptive radiotherapytreatment planning and tested the accuracy. It is feasible to use kV‐CBCT to determine dosimetric consequences resulting from tumor volume changes. The kV‐CBCT has potential to become a very useful tool for adaptive radiotherapytreatment planning.

SU‐E‐I‐68: The Relationship Between White Matter Tract Abnormalities and Brain Atrophy Correlation Analysis in Neurodegenerative Disease

Purpose: We evaluated the relationship between white matter (WM) tract disintegration and gray matter (GM) atrophy in patients with Alzheimer’s disease (AD), mild cognitive impairment (MCI) and controls, using diffusion tensor imaging (DTI) and an optimized voxel-based analy Methods: Two hundred individuals (60 controls, 100 MCI and 40 AD) were included. Voxel-based WM tract statistics was used to obtain wholebrain maps of WM bundles for FA. Voxel-based morphometry (VBM) was conducted to detect regions of gray matter (GM) atrophy in the AD, MCI group relative to the control group. FA maps were processed to make voxelwise comparison of tract based analysis in whole brain between each the two groups. The relationship between locations of abnormalities in the WM and GM were examined Results: Patients with AD showed significant GM atrophy in posterior cingulate gyrus (BA31, 32) to the precuneus, the middle temporal lobe (BA19), the superior frontal (BA9) to the anterior cingulate (BA 32), the medial frontal lobe (BA 11, BA25), the hippocampus, the parahippocampal gyrus (BA30/34) and the insula, and WM tract disintegrity of the uncinate fasciculus, posterior cingulate fasciculus and fornix compared with the control and MCI groups. These abnormalities in the AD group were caused by either structural changes in GM atrophy or neural dysfunction due to functional disconnections in the WM tract Conclusion: The GM atrophy resulting from WM tract disintegration or GM atrophy itself may be the first step in the AD process, resulting in anatomically congruent correlations between WM disintegration and regional GM atrophy. Using tract based spatial statistics and voxel based analysis, both of which are useful in investigating GM and WM changes in individuals with neurodegenerative disorders

SU‐E‐T‐264: Development of Dose Response Analysis Program for Basic Radiobiological Modeling

Purpose: To verify and quantify various dose responses including estimated survival fraction(SF) through clonogenic assay, estimated model parameters and its uncertainty, and relative biological effectiveness(RBE) and its uncertainty for each model. Methods: An user-friendly program, dose response analysis program(DREAP, ver.2.0) was developed by using Matlab. The program can provide two types of calculation modes at present. First, the “calculation of SF” mode is designed for giving estimated SF curves, model parameters, and its uncertainty at specific confidence level. it provides five types of established SF models such as linear quadratic(LQ), universal survival curve(USC), multi-target single-hit(MTSH) model, and repair kinetics models including repair mis-repair(RMR) and lethal potentially-lethal(LPL) model. Second, the “calculation of RBE” mode is made for giving estimated RBEs at a broad range of survival levels and its uncertainty at 95 percent confidence level. This mode gives three established SF models except for repair kinetics models. All the modes include basic analysis and comparison tools for each mode. And, all relevant and quantitative results can be easily exported to excel format by one mouse-click. Results: The “calculation of SF” mode can give SF curve through clonogenic assay data, and its uncertainty for each five SF models. Also, the “calculation of RBE” mode can provide RBE and its uncertainty for each three SF models. Since these modes have a feature of interactive and user-friendly structure, the user can easily quantify and access to a variety of dose responses results. Conclusion: The program can provide an easy way to access dose response results with interactive graphical user interfaces(GUIs). The features stated above will make the program practical to use for particle therapy center which needs to collect expected model parameters and its uncertainty, and manage meaningful RBE database.

SU‐E‐T‐656: Quantitative Analysis of Proton Boron Fusion Therapy (PBFT) in Various Conditions

Purpose: Three alpha particles are concomitant of proton boron interaction, which can be used in radiotherapy applications. We performed simulation studies to determine the effectiveness of proton boron fusion therapy (PBFT) under various conditions. Methods: Boron uptake regions (BURs) of various widths and densities were implemented in Monte Carlo n-particle extended (MCNPX) simulation code. The effect of proton beam energy was considered for different BURs. Four simulation scenarios were designed to verify the effectiveness of integrated boost that was observed in the proton boron reaction. In these simulations, the effect of proton beam energy was determined for different physical conditions, such as size, location, and boron concentration. Results: Proton dose amplification was confirmed for all proton beam energies considered (< 96.62%). Based on the simulation results for different physical conditions, the threshold for the range in which proton dose amplification occurred was estimated as 0.3 cm. Effective proton boron reaction requires the boron concentration to be equal to or greater than 14.4 mg/g. Conclusion: We established the effects of the PBFT with various conditions by using Monte Carlo simulation. The results of our research can be used for providing a PBFT dose database.

SU-E-T-258: Development of a New Patient Set-Up Monitoring System Using Force Sensing Resistor (FSR) Sensor for the Radiation Therapy

Purpose: The purpose of this work is to develop a new patient set-up monitoring system using force sensing resistor (FSR) sensors that can confirm pressure of contact surface and evaluate its feasibility. Methods: In this study, we focused on develop the patient set-up monitoring system to compensate for the limitation of existing optical based monitoring system, so the developed system can inform motion in the radiation therapy. The set-up monitoring system was designed consisting of sensor units (FSR sensor), signal conditioning devices (USB cable/interface electronics), a control PC, and a developed analysis software. The sensor unit was made by attaching FSR sensor and dispersing pressure sponge to prevent error which is caused by concentrating specific point. Measured signal from the FSR sensor was sampled to arduino mega 2560 microcontroller, transferred to control PC by using serial communication. The measured data went through normalization process. The normalized data was displayed through the developed graphic user interface (GUI) software. The software was designed to display a single sensor unit intensity (maximum 16 sensors) and display 2D pressure distribution (using 16 sensors) according to the purpose. Results: Changes of pressure value according to motion was confirmed by the developed set-up monitoring system. Very small movement such as little physical change in appearance can be confirmed using a single unit and using 2D pressure distribution. Also, the set-up monitoring system can observe in real time. Conclusion: In this study, we developed the new set-up monitoring system using FSR sensor. Especially, we expect that the new set-up monitoring system is suitable for motion monitoring of blind area that is hard to confirm existing optical system and compensate existing optical based monitoring system. As a further study, an integrated system will be constructed through correlation of existing optical monitoring system. This work was supported by the Industrial R&D program of MOTIE/KEIT. [10048997, Development of the core technology for integrated therapy devices based on real-time MRI guided tumor tracking] and the Mid-career Researcher Program (2014R1A2A1A10050270) through the National Research Foundation of Korea funded by the Ministry of Science, ICT&Future Planning.

SU-E-T-316: The Design of a Risk Index Method for 3D Patient Specific QA

PURPOSE To suggest a new guidance for the evaluation of 3D patient specific QA, a structure-specific risk-index (RI) method was designed and implemented. METHODS A new algorithm was designed to assign the score of Pass, Fail or Pass with Risk to all 3D voxels in each structure by improving a conventional Gamma Index (GI) algorithm, which implied the degree of the risk of under-dose to the treatment target or over-dose to the organ at risks (OAR). Structure-specific distance to agreement (DTOA), dose difference and minimum checkable dose were applied to the GI algorithm, and additional parameters such as dose gradient factor and dose limit of structures were used to the RI method. Maximum passing rate (PR) and minimum PR were designed and calculated for each structure with the RI method. 3D doses were acquired from a spine SBRT plan by simulating the shift of beam iso-center, and tested to show the feasibility of the suggested method. RESULTS When the iso-center was shifted by 1 mm, 2 mm, and 3 mm, the PR of conventional GI method between shifted and non-shifted 3D doses were 99.9%, 97.4%, and 89.7% for PTV, 99.8%, 84.8%, and 63.2% for spinal cord, and 100%, 99.5%, 91.7% for right lung. The minimum PRs from the RI method were 98.9%, 96.9%, and 89.5% for PTV, and 96.1%, 79.3%, 57.5% for spinal cord, and 92.5%, 92.0%, 84.4% for right lung, respectively. The maximum PRs from the RI method were equal or less than the PRs from the conventional GI evaluation. CONCLUSION Designed 3D RI method showed more strict acceptance level than the conventional GI method, especially for OARs. The RI method is expected to give the degrees of risks in the delivered doses, as well as the degrees of agreements between calculated 3D doses and measured (or simulated) 3D doses.

SU-D-BRD-01: Cloud-Based Radiation Treatment Planning: Performance Evaluation of Dose Calculation and Plan Optimization.

PURPOSE To report the first experience on the development of a cloud-based treatment planning system and investigate the performance improvement of dose calculation and treatment plan optimization of the cloud computing platform. METHODS A cloud computing-based radiation treatment planning system (cc-TPS) was developed for clinical treatment planning. Three de-identified clinical head and neck, lung, and prostate cases were used to evaluate the cloud computing platform. The de-identified clinical data were encrypted with 256-bit Advanced Encryption Standard (AES) algorithm. VMAT and IMRT plans were generated for the three de-identified clinical cases to determine the quality of the treatment plans and computational efficiency. All plans generated from the cc-TPS were compared to those obtained with the PC-based TPS (pc-TPS). The performance evaluation of the cc-TPS was quantified as the speedup factors for Monte Carlo (MC) dose calculations and large-scale plan optimizations, as well as the performance ratios (PRs) of the amount of performance improvement compared to the pc-TPS. RESULTS Speedup factors were improved up to 14.0-fold dependent on the clinical cases and plan types. The computation times for VMAT and IMRT plans with the cc-TPS were reduced by 91.1% and 89.4%, respectively, on average of the clinical cases compared to those with pc-TPS. The PRs were mostly better for VMAT plans (1.0 ≤ PRs ≤ 10.6 for the head and neck case, 1.2 ≤ PRs ≤ 13.3 for lung case, and 1.0 ≤ PRs ≤ 10.3 for prostate cancer cases) than for IMRT plans. The isodose curves of plans on both cc-TPS and pc-TPS were identical for each of the clinical cases. CONCLUSION A cloud-based treatment planning has been setup and our results demonstrate the computation efficiency of treatment planning with the cc-TPS can be dramatically improved while maintaining the same plan quality to that obtained with the pc-TPS. This work was supported in part by the National Cancer Institute (1R01 CA133474) and by Leading Foreign Research Institute Recruitment Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (MSIP) (Grant No.2009-00420).

SU-E-J-48: Development of An Abdominal Compression Device for Respiratory Correlated Radiation Therapy

PURPOSE The aim of this study is to develop the abdominal compression device which could control pressure level according to the abdominal respiratory motion and evaluate its feasibility. METHODS In this study, we focused on developing the abdominal compression device which could control pressure level at any point of time so the developed device is possible to use a variety of purpose (gating technique or respiratory training system) while maintaining the merit of the existing commercial device. The compression device (air pad form) was designed to be able to compress the front and side of abdomen and the pressure level of the abdomen is controlled by air flow. Pressure level of abdomen (air flow) was determined using correlation data between external abdominal motion and respiratory volume signal measured by spirometer. In order to verify the feasibility of the device, it was necessary to confirm the correlation between the abdominal respiratory motion and respiratory volume signal and cooperation with respiratory training system also checked. RESULTS In the previous study, we could find that the correlation coefficient ratio between diaphragm and respiratory volume signal measured by spirometer was 0.95. In this study, we confirmed the correlation between the respiratory volume signal and the external abdominal motion measured by belt-transducer (correlation coefficient ratio was 0.92) and used the correlated respiratory volume data as an abdominal pressure level. It was possible to control the pressure level with negligible time delay and respiratory volume data based guiding waveforms could be properly inserted into the respiratory training system. CONCLUSION Through this feasibility study, we confirmed the correlation between the respiratory volume signal and the external abdominal motion. Also initial assessment of the device and its compatibility with the respiratory training system were verified. Further study on application in respiratory gated therapy and respiratory training system will be investigated. This work was supported by Radiation Technology R&D program (No. 2013M2A2A7043498)and Basic Atomic Energy Research Institute (BAERI)(No. NRF-2009-0078390) through the National Research Foundation of Korea funded by the Ministry of Science, ICT&Future Planning.