bluuebunny/crossref_metadata_2025 huggingface dataset:
TH‐A‐134‐01: Breast Imaging QA
Authors: Geiser W , Reeve D
Published: July 2013

Implementation of a New Breast Tomosynthesis Program: A Clinical Medical Physicist's Experience‐W Geiser Digital breast tomosynthesis (DBT) was approved by the FDA as a screening tool for breast cancer in February 2011. Many systems were preinstalled as 2D systems and are now being upgraded for DBT and there is evidence that DBT is helping reduce recall rates while increasing cancer detection rates. As of February 2013 there were approximately 500 systems certified by the FDA for DBT and it is expected that there will be more than 700 certified systems by the third quarter of 2013. Facilities implementing a breast tomosynthesis program need to be aware that there are many hurdles to be overcome before tomosynthesis studies can be performed. The purpose of this lecture is to provide medical physicists assisting facilities that are upgrading 2D systems or installing new DBT systems, the knowledge to assist with facility design, image storage requirements, choice of PACS, and optimization of diagnostic review. New educational requirements for medical physicists to qualify to perform acceptance testing and continued annual testing of DBT systems will also be reviewed.

Learning Objectives:

1. Be able to assist with implementation of breast tomosynthesis at their facility.

2. Know the process for accreditation and certification of DBT systems.

3. Understand additional shielding requirements and facility design for a facility installing digital breast tomosynthesis.

Breast MR Imaging and Quality Control — D Reeve

MR imaging of the breast is an important adjunct to mammography and ultrasound for the detection of breast cancer and for breast biopsy guidance. Diagnostic breast MRI protocols typically include T2‐weighted fat saturated images and 3D T1‐weighted dynamic contrast enhanced (DCE) multiphase images using a Gadolinium‐based contrast agent. The DCE images are used to determine the kinetic signature of enhancing tissues in order to differentiate between benign and malignant lesions. MR spectroscopy and diffusion weighted images (DWI) may also be acquired in order to provide additional diagnostic information.

The diagnostic value of breast MRI scans can be improved by choosing acquisition parameters that optimize image quality parameters such as SNR, contrast and spatial resolution. As with any MRI protocol, achieving the desired image quality must balance the need for acceptable scan times. The timing and temporal resolution of the DCE series are important considerations.

Breast radiofrequency (RF) coils are phased array coils capable of simultaneous bilateral imaging. A comprehensive breast MRI quality control program is important to assess the performance of the MRI system as well as the breast RF coils.

Learning Objectives:

1. Provide an overview of breast MR imaging and MR‐guided biopsy procedures.

2. Describe breast MR image quality criteria and protocol optimization.

3. Discuss the components of a breast MRI quality control program.
TH‐C‐105‐01: Medical Physics Practice Guidelines
Authors: Prisciandaro J , Chan M , Fontenot J , Cody D
Published: July 2013

The AAPM has long advocated a consistent level of medical physics practice, and has published many recommendations and position statements toward that goal, such as Science Council Task Group reports related to calibration and quality assurance, Education Council and Professional Council Task Group reports related to education, training, and peer review, and Board‐approved Position Statements related to the Scope of Practice, physicist qualifications, and other aspects of medical physics practice. Despite these concerted and enduring efforts, the profession does not have clear and concise statements of the acceptable practice guidelines for routine clinical medical physics. As accreditation of clinical practices becomes more common, Medical Physics Practice Guidelines (MPPGs) will be crucial to ensuring a consistent benchmark for accreditation programs. To this end, the AAPM has recently endorsed the development of MPPGs, which may be generated in collaboration with other professional societies. The MPPGs are intended to be freely available to the general public. Accrediting organizations, regulatory agencies and legislators will be encouraged to reference these MPPGs when defining their respective requirements. MPPGs are intended to provide the medical community with a clear description of the minimum level of medical physics support that the AAPM would consider to prudent in all clinical practice settings. Support includes but is not limited to staffing, equipment, machine access, and training. These MPPGs are not designed to replace extensive Task Group reports or review articles, but rather to describe the recommended minimum level of medical physics support for specific clinical services. This session will describe the purpose, scope, and procedure for development of MPPGs and introduce the first two recently published MPPGs: (1) IGRT Commissioning and QA, and (2) CT Protocol Management and Review.

Learning Objectives:

1. Understand the purpose and scope of MPPG from the AAPM

2. Understand the benefits and process of the development of MPPG by the AAPM

3. Introduce the first two AAPM MPPGs
TH‐C‐137‐05: A MOrphing Technique That Projects 3D Surface Objects to a STandard Metric (MOST); Geometric Modeling of Cervix Cancer Patients for Adaptive Radiation Treatment
Authors: Oh S , Cho Y
Published: July 2013

Purpose: Adaptive radiation therapy (ART) had been proposed based in order to correct the dosimetric discount due to geometric variations by means of feedback control. Numerical modeling of inter‐and intra‐patients' geometric variations is one of the important parts in ART. To this end, a MOrphing technique that projects 3D surface objects to a STandard metric (MOST) was developed. Methods: A total of 174 clinical target volumes (CTVs) were obtained from 32 patients and used to evaluate the MOST. The MOST consists of three main steps; 1) deforming 3D mesh of CTVs to a sphere by parametric active contour (PAC) model, 2) sampling the deformed mesh at evenly distributed girds to be the standard metric, and 3) projecting the 3D data into 2D plane for further analysis. The performance of the MOST was evaluated with respects to 1) iteration number, 2) computation time, and 3) residual deformation, the residual distance between a sphere surface and the deformed node. Result: MOST successfully transformed complex 152 meshes from 28 patients to the standard metric. Convergence was achieved with average iteration of 65 and one standard deviation (STD) of 74 for 137 cases. The computation time was 17.8 hours and this corresponds to 51.3% of the time for all 152 cases. The average±STD of residual deformation was 0.9±0.7‐mm and more than 98% nodes had less than 3‐mm residual deformation. Conclusions: MOST demonstrated its ability to transform complex 3D meshes of cervix cancer into a simple standard metric. Inter‐and intra‐patients' geometric variation could be directly compared and analyzed using the transformed results by virtue of the regularity of standard metric. Numerical modeling of tumor dynamics, implemented using this technique, may provide a systematic way for the estimation of tumor evolution and optimal correctional action for ART. This study is supported by funding from Ray Search Laboratories and Ontario Consortium for Adaptive Interventions Radiation Oncology (OCAIRO).
TH‐C‐137‐09: A Knowledge Based Implementation of a Fully Automated Treatment Planning System
Authors: Wang H , Xing L
Published: July 2013

Purpose: Currently, there is no effective way to automate the treatment planning process. The most common approach is to use criteria from a selected plan from a database and apply those configurations to the plan you want to work with. We proposed a direct mapping between any two given plans. We found a way to cleverly use information from one plan to the next, regardless of how different or similar they are. Methods: We have broken the entire automation process into two stages. In the first stage, we find a transformation between the two given patient. We find this transformation using the prescribed dose for the new plan and calculated dose from template plan. We apply this transformation and as a Result provide a coarse tuning. In the second stage, we use a voxel‐based penalty scheme to provide a finer tuning. The rationale behind this fine‐tuning stage is no matter how similar two plans are, there are inevitable differences we cannot account for. We evaluate this novel knowledge based system against manual planning for assessment. Results: We implemented a Visual Studio interface that automatically controls the Varian Eclipse's Beam Treatment Planning. No user intervention is needed for the entire planning duration. We compared the dose volume histogram between the automated plans and manual plan and observed nearly identical results. We also achieved up to 86x speed up between using knowledge from another plan versus starting completely from scratch. Conclusion: Knowledge based system would transform the treatment planning process into a completely automated procedure. This work has the potential to be a promising platform for developing treatment plans and afford a powerful way to reliably automate the treatment planning process. It could have major predictive value to save clinical time in developing a cancer treatment plan.
TH‐C‐137‐10: Development of a GPU Research Platform for Automatic Treatment Planning and Adaptive Radiotherapy Re‐Planning
Authors: Gautier Q , Tian Z , Graves Y , Li N , Zarepisheh M , Sutterley C , Shi F , Cervino L , Jia X , Jiang S
Published: July 2013

Purpose: To develop a research platform called SCORE (Super Computing Online Re‐planning Environment) for automatic treatment planning and adaptive radiotherapy re‐planning based on GPU. Methods: Our software is a Graphical User Interface (GUI) based on the Qt framework that allows users to easily and quickly create a new treatment plan based on a reference plan. It consists of several modules, including loading plan and patient geometry from DICOM RT files, automatic and manual rigid registration, deformable registration for contour propagation, previous plan based automatic plan optimization, physician‐driven plan tuning, final dose calculation, and plan exporting in DICOM RT format. For automatic planning, a reference plan is identified from a library of previously delivered plans and it is used to guide the optimization process. For adaptive radiotherapy re‐planning, the original plan of the same patient is used as the reference plan to guide the optimization process to generate a new plan on the new patient geometry defined by either a new CT or Cone‐Beam CT image. All the computation modules have been implemented in CUDA to achieve high efficiency. The results for each step of the workflow can be visualized for review, revision, and approval. Results: SCORE has been well tested and validated for prostate and head/neck cancer cases. The validation was done by comparing SCORE plans against the same plans with re‐calculated dose distributions and DVHs using a commercial planning system. We found that SCORE can generate clinically optimal treatment plans that are realistic and deliverable. The plans can be automatically created in only a few minutes, followed by another few minutes of physician fine‐tuning using an interactive GUI. Conclusion: We have developed a very efficient and user‐friendly GPU‐based research platform that can be used for clinical research on automatic treatment planning and adaptive radiotherapy re‐planning.
TH‐C‐WAB‐02: Interactive Segmentation of Structures in the Head and Neck Using Steerable Active Contours
Authors: Kolesov I , Karasev P , Shusharina N , Vela P , Tannenbaum A , Sharp G
Published: July 2013

Purpose: The purpose of this work is to investigate the performance of an interactive image segmentation method for radiotherapy contouring on computed tomography (CT) images. Manual segmentation is a time consuming task that is essential for treatment. Due to the low contrast of target structures, their similarity to surrounding tissue, and the required precision for the final segmentation Result, automatic methods do not exhibit robust performance. Furthermore, when an automatic segmentation algorithm produces errors at the structure boundary, they are tedious for a human user to correct. For this experiment, it is hypothesized that an interactive algorithm can attain ground truth results in a fraction of the the time needed for manual segmentation. Methods: The proposed method is interactive segmentation that tightly couples a human “expert user” with a framework from computer vision called “active contours” to create a closed loop control system. As a Result, the strengths (i.e., quickly delineating complicated target boundaries) of the automatic method can be leveraged by the user, who guides the algorithm based on his expert knowledge throughout the process. Experimental segmentations have been performed both with and without the control system feedback, the accuracy of the resulting labels will be compared along with the time required to create the labels. Results: Four structures were evaluated: left/right eye ball, brain stem, and mandible. Tests show that virtually identical segmentations are performed with and without control system feedback. However, the time required to complete the task is significantly less than what is needed for fully manual contouring. Conclusion: Interactive segmentation using control system feedback is shown to reduce the time and effort needed to segment targets in CT volumes of the head and neck region. This project was supported by grants from the National Center for Research Resources (P41‐RR‐013218) and the National Institute of Biomedical Imaging and Bioengineering (P41‐EB‐015902) of the National Institutes of Health. This work was also supported by the NIH grant R01 MH82918 as well as a grant from AFOSR. This work is part of the National Alliance for Medical Image Computing (NAMIC), funded by the National Institutes of Health through the NIH Roadmap for Medical Research, Grant U54 EB005149. Information on the National Centers for Biomedical Computing can be obtained from http://nihroadmap.nih.gov/bioinformatics.
TH‐C‐WAB‐03: A Robust Intensity Similarity Measure for Multi‐Atlas Segmentation
Authors: Sharp G , Peroni M , Shusharina N , Shackleford J , Golland P , Baroni G
Published: July 2013

Purpose: Atlas‐based segmentation is a general approach to automatic segmentation that labels regions of an image based on their alignment to existing structures in an atlas image. The atlas‐based approach can be improved by aligning multiple atlases with the target image, and fusing their results. A typical strategy for multi‐atlas segmentation is weighted voting that combines structure distance with intensity similarity. This abstract investigates the use of a robust measure for penalizing the similarity of voxel intensities when voting. Methods: Experiments were performed comparing the robust measure, a truncated quadratic penalty, with the more commonly used quadratic penalty. An atlas database of 20 subjects with structures segmented on head and neck CT were evaluated. Training parameters were tuned using leave‐one‐out cross validation. Results: Automatic segmentation results were evaluated using the Dice similarity coefficient. The average Dice scores for segmentations produced with a quadratic penalty were 0.78 for brainstem; 0.78 and 0.77 for left and right eye balls; 0.66 and 0.64 for left and right parotids. The average Dice scores for segmentations produced with the truncated quadratic penalty were 0.82 for brainstem; 0.85 and 0.84 for left and right eye balls; 0.74 and 0.73 for left and right parotids. Conclusion: A robust intensity similarity measure, such as a truncated quadratic penalty, can be an effective approach for improving overall segmentation quality for multi‐atlas methods. National Institutes of Health
TH‐C‐WAB‐05: Blind Functional Volume Segmentation in PET
Authors: Tan S , Lu W
Published: July 2013

Purpose: To propose a blind PET functional volume segmentation method that does not need any prior calibrations. Methods: The partial volume effect (PVE) in PET imaging was considered as a forward problem that convolves the original target object with the point spread function (PSF) of the PET scanner, and made a PET image blurred. We showed that the optimal threshold for accurate object localization in a PET image is a function of the ratio of the object size to the PSF standard variance. We defined a new quantity, the optimal volume ratio (OAR), which represents the ratio of the segmented volume when using the optimal threshold to the whole target volume with greater activity than the background. The OAR can be expressed as a function of the optimal threshold, and was then used to derive the optimal threshold through a sequence of region growing algorithms with different thresholds. The new method avoids solving the ill‐conditioned inverse problem, and is fully blind to the PET scanner. The proposed method was tested on PET phantom with known object location and extension, and its robustness with respect to source‐to‐background ratio (SBR) and object size was evaluated. Results: At all SBR levels and for all object sizes, the new blind segment method performed similarly to existing methods with prior calibrations, and outperformed existing methods that do not take into account PVE. In addition, the new blind segment method is robust to the changes of SBR level and object size. Conclusion: The results showed that the proposed blind method did not need any prior calibrations and performed well for the functional volume segmentation in PET.
TH‐C‐WAB‐07: Optimization of Heart Block in the Left‐Sided Whole Breast Irradiation
Authors: Yue N , Goyal S , Park J , Jones S , Xu X , Khan A , Haffty B , Chen T
Published: July 2013

Purpose: Blocks have been used to protect heart from potential radiation damage in left breast treatments. Since cardiac motion pattern may not be fully captured on co nventional 3DCT or 4DCT simulation scans, this study was intended to investigate the optimization of the heart block design taking the cardiac motion into co nsideration. Methods: Whole breast treatment plans using two opposed tangential fields were designed based on 4DCT simulation images for 10 left breast patients. Using an OBI system equipped to a Varian Linac, beam‐eye viewed fluorosco py images were acquired for each of the treatment beams after patient treatment setup, and the MLC heart blocks were overlaid onto the fluorosco py images with an in‐house software package. A non‐rigid image registration and tracking algorithm was utilized to track the cardiac motion on the fluorosco py images with minimal manual delineation, and the tracked cardiac motion information was used to optimize the heart block design to minimize the radiation damage to heart while avoiding the over‐shielding that may lead to underdosing breast tissues. Results: Heart moved under the influences of both respiratory and cardiac motion. For 4 out of 10 patients, it was observed that heart moved beyond the heart block into treatment fields. The average size of the heart portion irradiated inside the treatment fields was 0.4 mm (0.4mm‐0.4 mm), 3.6 mm (0.8 mm – 5.1 mm), 4.2 mm (0.4mm – 6.3mm), and 3.9 mm (0.2 mm–5.7mm) for the four patients, respectively. The optimization process changed the positions of 1, 8, 10, and 5 MLC leaves (5 mm wide per leaf) respectively to achieve the optimal heart protection. Co nclusion: Simulation 4DCT based heart block design may not provide adequate heart protection for all the treatments. A fluorosco py‐based method has been developed to adaptively optimize the heart MLC block to achieve optimal heart protection.
TH‐C‐141‐01: Differentiation of Air From Bone Using MRI for Radiation Therapy and PET‐MRI Reconstruction
Authors: Hsu S , Cao Y , Balter J
Published: July 2013

Purpose: Differentiating air from bone is challenging with conventional MR images. While ultrashort TE (UTE) techniques have shown some promise, factors including noise, partial volume averaging, and imaging artifacts all may limit the discriminatory power of this technique. Methods: A biological phantom containing bone, bone marrow, solid tissue (with an air cavity), and fat was scanned with an 18‐channel surface coil on a 3T MR scanner (Siemens SKYRA). MRI volumes acquired included T1‐weighted gradient echo (TE 2.5 ms), T2‐weighted fast spin echo (TE 88 ms), and two echoes from a UTE acquisition (UTE1 TE 0.06 and UTE2 TE 4.46 ms). CT images for the phantom were acquired to define “true” air and bone regions using thresholds of −600 and 145, respectively. A range of intensity thresholds was used to test sensitivity in defining air regions in T1, T2, UTE1, UTE2 and difference of the UTE1 and UTE2 images. The number of voxels labeled as air in MR images and within air and bone regions defined in CT images were counted to calculate sensitivity and specificity. ROC curves were generated to evaluate bone and air discrimination in different MR image types. Results: ROC curves did not cross for the individual image types tested. UTE1 had the greatest discriminatory power (AUC 0.944), followed by UTE1–UTE2 (0.906), UTE2 (0.869), T1 (0.750), and T2 (0.651). UTE1 could not completely separate air from bone, generating false positive locations of air within the CT‐defined bone region of interest at sensitivities of 0.756 and higher for labeling air within the cavity defined on CT. Conclusion: While UTE1 reasonably separates air from bone, the persistence of false labeling of bone as air warrants further investigation. Subtraction of UTE1 and UTE2 did not improve sensitivity/specificity, indicating no added value of the 4.46 ms TE in separating bone from air.
TH‐C‐141‐06: Estimating Cell Density Using Fractional Anisotropy From Postoperative Diffusion Tensor Imaging of High‐Grade Gliomas
Authors: Kosztyla R , Moiseenko V , Reinsberg S , Ma R , McKenzie M , Wilson D , Benard F , Vertinsky T , Toyota B , Nichol A
Published: July 2013

Purpose: Fractional anisotropy (FA) from diffusion tensor imaging (DTI) has been suggested as a predictor of glioma cell density and proliferation activity. The purpose of this study is estimate the glioma cell density inside high‐grade glioma radiotherapy target volumes using FA images. Methods: Five patients with histologically‐confirmed glioma underwent radiotherapy planning with postoperative magnetic resonance imaging (MRI) and computed tomography. T1‐weighted images with gadolinium contrast enhancement and T2‐weighted fluid attenuated inversion recovery images used for treatment planning were obtained. DTI was obtained using echo planar imaging for 20 noncolinear directions with b=1000 s/mm2 and one additional image with b=0. Diffusion imaging was repeated four times for signal averaging. The gross tumor volume (GTV) was delineated using T1‐weighted and T2‐weighted images. A clinical target volume (CTV) was defined as a 2‐cm expansion of the GTV and a shell volume (CTV‐shell) between the GTV and CTV contours was created. The distribution of FA inside the GTV, CTV‐shell, and normal brain tissue was calculated. Cell density inside the CTV was estimated from FA values using a linear model. Results: The mean FA inside the GTV was 0.13±0.08 and inside CTV‐shell was 0.20±0.12. The mean FA in normal brain tissue (0.28±0.12) was significantly higher than the mean FA inside the GTV (p=0.003) and CTV‐shell (p=0.01). The estimated mean cell density inside CTV‐shell was 1.57±0.94 times the mean cell density inside the GTV (p=0.02). Conclusion: FA values in the GTV and CTV‐shell were significantly smaller than values in normal brain regions. FA and estimated cell density values approached those of normal brain tissue as the distance from the GTV increased, consistent with the expectation of a gradual and decreasing presence of tumor cells. Further research is warranted to determine if treatment planning using FA images will improve treatment outcome.
TH‐C‐141‐08: A Feasibility Study of the Utility of Dynamic Contrast‐Enhanced MRI for Treatment Planning and Monitoring Treatment Response in Lung Stereotactic Body Radiation Therapy
Authors: Lewis J , Mamata H , Tokuda J , Mishra P , Hermann G , Hatabu H , Nishino M , Mak R
Published: July 2013

Purpose: To investigate the feasibility of pulmonary DCE‐MRI in 1) identifying regions of functional lung for lung SBRT treatment planning; 2) assessing tumor response during and after SBRT; and 3) characterizing regions of radiation‐induced lung injury after SBRT. Methods: In this IRB‐approved feasibility study, participants being treated with 3–5 fractions of 12–18 Gy undergo pulmonary DCE‐MRI at baseline, during treatment (1–2 days after first fraction) and post‐treatment (1–2 weeks and then 3–4 months). DCE‐MRI is performed using a clinical 3D DCE‐MRI protocol, that includes T2‐weighted HASTE, T1‐weighted VIBE, and 3D turbo FLASH sequences. The parameters for the 3D turbo FLASH were: TR/TE=2.2/0.84msec, FOV=400mm, 256×208, slice thickness 3.6 mm, 1 excitation, BW=930kHz, FA=10, coronal orientation, temporal resolution=4sec, 42 frames, Gd‐DTPA iv. 0.1 mmol/kg. Time‐intensity curves are derived after motion‐correction, and fit to a two‐compartment plasma/extracellular extravascular space (EES) model to derive pharmacokinetic parameters for the tumor and surrounding treated lung, including kep, the characteristic rate of transfer of contrast tracer between plasma and the EES. The study aims to enroll 20 patients, with a preliminary assessment of feasibility after 7 patients. Results: The first patient was enrolled, and all the 4 MRI studies were successfully completed within the timeframe defined by the protocol, without complications. Images of the lung and tumor were obtained with satisfactory quality for pharmacokinetic analysis. Pharmacokinetic parameter maps based on DCE‐MRI were generated and registered to the corresponding planning 4DCT for each scan. In this first patient, kep in a tumor ROI was 1.09 before treatment, 0.20 after 2 fractions of 18 Gy, and 0.76 two weeks after the final fraction. Conclusion: The feasibility of acquiring and incorporating information from DCE‐MRI into lung stereotactic body radiation therapy has been demonstrated on an initial patient. Quantitative analysis will be performed after accrual of more participants. Kaye Scholar Grant and Siemens Research Partnership Grant
TH‐C‐103‐05: A Novel Method to Improve Single Phase Reconstruction Quality From Conventional CBCT Dataset
Authors: Hu E , Lasio G , Yu C , Lee S , Yi B
Published: July 2013

Purpose: to present a method to generate retrospectively a pre‐selected motion phase cone‐beam CT image from the full motion cone‐beam CT acquired at standard rotation speed. Materials and Methods: the method consists of subtracting from the full CBCT all of the undesired motion phases and obtain a motion de‐blurred single‐phase CBCT image CTnm. This is accomplished by means of a subtraction CBCT (CTs) added to the full CBCT (CTm). CTs is obtained as follows: i) we sort the CBCT projections into each phase bin k according to the known motion trace; ii) compute the digitally reconstructed radiographs (DRR) from the full reconstruction at the gantry angles correlated to bin k; iii) generate a set of subtraction projections for phase k by subtracting the DRR from the original projection at the same gantry angle; v) reconstruct CTs from this single‐phase subtraction projection set; vi) add CTs to CTm to obtain CTnm. A qualitative assessment of the image quality improvement was performed using a simple shapes phantom. To quantitatively study the method, we used the image quality modules of a Catphan phantom, evaluated in a static scan and under anterior‐posterior motion. Results: The single phase CBCT reconstruction generated by our method successfully isolates the desired motion phase from the full motion CBCT, effectively reducing motion blur. It also shows improved image quality, with reduced streak artifacts with respect to the reconstructions from unprocessed phase‐sorted projections only. Conclusions: A novel CBCT motion de‐blurring algorithm has been developed and tested with phantom data. The algorithm allows to improve visualization of a single phase motion extracted from a standard CBCT dataset. NIH R01CA133539
TH‐C‐103‐10: AIR: Fused Analytical and Iterative Reconstruction Method for Computed Tomography
Authors: Yang L , Qi S , Gao H
Published: July 2013

Purpose: CT image reconstruction techniques can be classified roughly into two categories: analytical reconstruction method and iterative reconstruction method (IR). Analytical methods reconstruct images through analytical formulas, such as filtered backprojection (FBP) in 2D and FDK in 3D, which can be either mathematically exact or approximate. In contrast, IR is often based on the discrete forward model of X‐ray transform and formulated as a minimization problem with certain image regularization, so that the reconstructed image corresponds to the minimizer obtained after iterations. Each method has its own advantages. This work is to investigate the fused analytical and iterative reconstruction method (AIR). Methods: As a 2D example of AIR, FBP is incorporated into tensor framelet (TF) based IR. Specifically, AIR is formulated as a L1‐type optimization problem. The data fidelity term consists of the discrete X‐ray transform with the preconditioner that is specific to FBP. The image regularization term is via TF. The formulated minimization problem is efficiently solved through split Bregman method with GPU‐accelerated X‐ray transform and its adjoint. Results: FBP, IR, and AIR were compared using experimental data that were acquired from a resolution phantom and a contrast phantom with TomoTherapy megavoltage CT. The reconstruction was performed with the regular fully sampled case (100% data) and the low‐dose undersampled case (25% data). Quantitative contrast and resolution evaluations were computed, including the full width at half maximum (FWHM) and the contrast‐to‐noise ratio (CNR). The experimental results suggest that AIR provides better image resolution than FBP or IR, and the reconstructed image contrast from AIR is comparable to that from IR, and better than that from FBP. Conclusion: AIR is proposed with a 2D example of FBP‐based TF‐regularized IR. Its superiority in terms of the resolution and the contrast for either regular or low‐dose scan has been established through experimental studies. This work is partially supported by NIH/NIBIB grant EB013387.
TH‐C‐116‐01: Managing Treatment Planning Systems
Authors: Chang J , Newman G , DeWyngaert K , Feng W
Published: July 2013

The radiotherapy treatment planning system has evolved over the years into a very powerful but complex software tool. Most modern treatment planning systems employ advanced information technologies (e.g., network, clientserver…) that allow multiple users to access patient data simultaneously and perform treatment plans from almost anywhere. Although these improvements have increased the efficiency of treatment planning process, they also pose serious challenges for medical physicists who are responsible for the data security and system management of the treatment planning system on the application level. In addition, the treatment planning system designed for clinical use is commonly used for research and education purposes, which put additional burden on system management. In this symposium we will use existing commercial Windows‐and Unix‐based systems to illustrate effective techniques for managing modern treatment planning systems for routine clinical use and for research and education. Topics will include:1.Introduction of information technologies: (a) client/server vs. centralized processing, (b) enterprise‐level systems, (c) motivation to move to centralized processing and (d) what to consider if planning a move.2.System management: (a) system manager, (b) user management, (c) privilege assignment, (d) scripting, (e) synchronize preferences, (f) database integrity, (g) backup and recovery, (h) plan locking, (i) anonymizing patient data, (j) policy and procedure, and (k) training.3.Research and Education: (a) challenge facing, (b) typical research settings, (c) user privilege considerations, (d) patient data sharing, (e) backup and recovery, (f) protocol accreditation and submission and (g) protocol/template sharing.

Learning Objectives:

1. Be familiar with the information technologies used by modern treatment planning systems.

2. Understand the scope and challenges of managing modern treatment planning systems.

3. Understanding the different requirement for research and education use

4. Be able to implement some management techniques introduced in the symposium.
TH‐C‐144‐01: BEST IN PHYSICS (THERAPY) – Use of Radiation‐Induced Ultrasound to Image Proton Dosimetry
Authors: Stantz K , Alsanea F , Moskvin V
Published: July 2013

Purpose: The objectives of this study are to simulate the ionizing radiation induced thermoacoustic signal from scanning proton beam; and investigate the various designs and techniques of ultrasound tomographic imaging to map three dimensional dose (3D) proton dose distributions. Methods: A 3D dose and proton fluence distribution in a water phantom from a scanning spot beam from a treatment nozzle was simulated using a Monte Carlo (MC) code FLUKA (v. 2012) for 6.5, 16 and 27 cm proton range. An initial radio‐acoustic computed tomographic (RCT) scanner design of a cylinder with 128 transducer array (0.5MHz center frequency; 50% bandwidth at −6dB; flat surface) centered along the height of the cylinder (z‐axis) at a radial distance of 15 cm was evaluated. The thermoacoustic generated pressure signals from the proton beam were simulated and digitally sampled for each transducer over time, which was rotated over 30 angles about isocenter. A 3D filtered backprojection algorithm was used to reconstruct the dosimetric image volume consisting of the Bragg peak (initially at 5×5×5mm3), and then compared to the MC results. Results: The comparison between the beam profiles as simulated by MC and measured from commissioning of the beam had an estimated deviation of about 2%. An analysis of the RCT intensity dependence on depth as compared to MC simulated data demonstrated that the distal edge of the Bragg peak was within binning size of the reconstruction image and MC position prediction, with an average variation in RCT intensity around 6%. Conclusion: This feasibility study demonstrates that RCT can be used to monitor the dose distribution and proton range in proton therapy. Additional scanner designs (geometry, transducer bandwidth consideration, phantom designs) will be investigated and presented, such as phase‐array methods. Acquiring measurement data to compare with the simulated data is work in progress.
TH‐C‐144‐03: Tissue Decomposition From Dual Energy CT Data to Reduce Range Uncertainties in Proton and Carbon Radiotherapy
Authors: Huenemohr N , Paganetti H , Greilich S , Jaekel O , Seco J
Published: July 2013

Purpose: To reduce uncertainties in CT data conversion to stopping power ratio (SPR) and tissue composition when using single energy CT (SECT), this study presents a first approach of exploiting dual energy CT (DECT) data for Monte Carlo (MC) based dose calculation in particle therapy. Methods: DECT image data can be converted into an electron density and effective atomic number image. With both tissue parameters elemental weights of 71 tabulated tissues were predicted by dedicated linear fits for each element. The mass density was derived via a single linear fit of the electron density from adipose on. Dose calculations with the MC system TOPAS were performed using monoenergetic pencil beams (protons and carbons) stopped in 12 selected tissues which showed considerable differences in composition predictions from single and dual energy CT. Ranges were compared with predictions from the novel DECT approach and the standard SECT. Results: Predictions of mass density, carbon and oxygen elemental weights profit highly from the additional DECT information. Maximum differences to the true mass density could be reduced from 3.0% (SECT) to 0.9% (DECT) for soft tissue and from 0.7% (SECT) to 0.1% (DECT) for bone tissue. Furthermore, DECT shows a significant improvement also in common tissues: range uncertainties in cartilage were reduced from 1.7% (SECT) to 0.2% (DECT), in yellow marrow from 1.7% (SECT) to 0.5% (DECT), in liver from 0.9% (SECT) to 0.2% (DECT), in brain cerebroisal fluid from 2.2% (SECT) to 0.0% (DECT) and in femur the predicted range deviates by 0.8% (SECT) to 0.0% (DECT) from the true value. Conclusion: DECT can provide more accurate material compositions and mass density as compared to single energy CT. Therewith, DECT information can significantly reduce range uncertainties in particle therapy and can lead to a reduction in currently applied range margins in proton and carbon ion therapy.
TH‐C‐144‐10: On the Feasibility of Prompt Gamma Imaging in Heterogeneous Patient Anatomy
Authors: Sterpin E , Janssens G , Smeets J , Prieels D , Stichelbault F , Roellinghoff F , Clementel E , Benilov A , Vynckier S
Published: July 2013

Purpose: A prompt gamma (PG) slit camera prototype recently demonstrated 1‐2 mm accuracy for the detection of range shifts of a proton pencil beam in a PMMA target. This accuracy is achieved thanks to the falloff of the prompt gamma profiles that is well correlated to the position of the Bragg peak. The present study investigates the potential of using such a camera for pencil beam scanning (PBS) in highly heterogeneous clinical situations. Methods: PG detection profiles were simulated using a new dedicated Monte Carlo (MC) tool called 4P (PENELOPE Proton for PBS treatment Planning) previously benchmarked with the MC code MCNPX. Efficiency is enhanced in 4P by 1) neglecting neutron transport; 2) forced sampling of ICRU 63 cross sections for PG emission. Image processing and data analysis were performed on the MatLab‐based REGGUI software. In a CT scan of the thorax, incident PBS beams were defined in such a way that the protons are crossing several materials with large differences of densities (soft, bone and lung tissues). PG profiles were computed for each beam and the correlation between the profile and Bragg‐peak was assessed in end‐exhale CT data. The simulation was then repeated on the end‐inhale phase. Results: In general, our results show that clean PG detection profiles can be retrieved in most of tested cases. Also, we could clearly distinguish PG detection profiles computed on end‐inhale and end‐exhale CT data in cases where the range is modified (see Figure 1). This could lead to an on‐line assessment of gating techniques. However, PG detection profiles can be greatly distorted if a beam stops right at a tumor‐to‐lung or lung‐to‐tumor interface. Conclusion: Our current results demonstrate that PG imaging remains of interest as a strong candidate for in vivo range verification despite the presence of heterogeneities. This work is partially supported by Ion Beam Application. Therefore, there is a potential conflict of interest.
TH‐E‐WAB‐01: MR Guided Therapy Planning
Authors: Paulson E , Cao Y , Cormack R
Published: July 2013

MRI has played a supportive role in radiation therapy for over two decades, and current observations and guidance suggest that this role will be increasing over the next several years. This symposium will explore some of the advances and questions related to using MRI as a key, if not solitary, imaging methodology in the planning of radiation therapy treatments. Both external beam radiation therapy as well as brachytherapy will be explored. Issues such as distortion, image quality, scanning time, optimization of MRI protocols, integration in the radiation therapy workflow, and knowledge and practice information of use to non‐diagnostic physicists will be explored.

Learning Objectives:

1. Understand the current and potential near future roles of MRI external beam radiation therapy

2. Understand current recommendations and future directions for MRI in brachytherapy

3. Understand the quality assurance and commissioning needs for MRI systems for the above uses

4. Understand the characteristics of modern MRI systems and the modifications and additional features that may facilitate radiation therapy use

Siemens Medical Systems
Mid frequency shallow water fine-grained sediment attenuation measurements
Authors: Holland Charles W. , Dosso Stan E.
Published: July 2013

Attenuation is perhaps the most difficult sediment acoustic property to measure, but arguably one of the most important for predicting passive and active sonar performance. Measurement techniques can be separated into “direct” measurements (e.g., via sediment probes, sediment cores, and laboratory studies on “ideal” sediments) which are typically at high frequencies, O(104–105) Hz, and “indirect” measurements where attenuation is inferred from long-range propagation or reflection data, generally O(102–103) Hz. A frequency gap in measurements exists in the 600–4000 Hz band and also a general acknowledgement that much of the historical measurements on fine-grained sediments have been biased due to a non-negligible silt and sand component. A shallow water measurement technique using long range reverberation is critically explored. An approximate solution derived using energy flux theory shows that the reverberation is very sensitive to depth-integrated attenuation in a fine-grained sediment layer and separable from most other unknown geoacoustic parameters. Simulation using Bayesian methods confirms the theory. Reverberation measurements across a 10 m fine-grained sediment layer yield an attenuation of 0.009 dB/m/kHz with 95% confidence bounds of 0.006–0.013 dB/m/kHz. This is among the lowest values for sediment attenuation reported in shallow water.
Speech intelligibility in hospitals
Authors: Ryherd Erica E. , Moeller Michael , Hsu Timothy
Published: July 2013

Effective communication between staff members is key to patient safety in hospitals. A variety of patient care activities including admittance, evaluation, and treatment rely on oral communication. Surprisingly, published information on speech intelligibility in hospitals is extremely limited. In this study, speech intelligibility measurements and occupant evaluations were conducted in 20 units of five different U.S. hospitals. A variety of unit types and locations were studied. Results show that overall, no unit had “good” intelligibility based on the speech intelligibility index (SII > 0.75) and several locations found to have “poor” intelligibility (SII < 0.45). Further, occupied spaces were found to have 10%–15% lower SII than unoccupied spaces on average. Additionally, staff perception of communication problems at nurse stations was significantly correlated with SII ratings. In a targeted second phase, a unit treated with sound absorption had higher SII ratings for a larger percentage of time as compared to an identical untreated unit. Taken as a whole, the study provides an extensive baseline evaluation of speech intelligibility across a variety of hospitals and unit types, offers some evidence of the positive impact of absorption on intelligibility, and identifies areas for future research.
Stress-meter alignment in French vocal music
Authors: Temperley Nicholas , Temperley David
Published: July 2013

Previous research has shown disagreement regarding the nature of stress in French. Some have maintained that French has lexical stress on the final syllable of each word; others have argued that French has no lexical stress, only phrasal stress. A possible source of evidence on this issue is vocal music. In languages with lexical stress, such as English, it is well known that stressed syllables tend to occur at “strong” positions in the musical meter (some evidence will be presented supporting this view). A corpus analysis was performed to investigate the degree of stress-meter alignment in French songs. The analysis showed that (excluding syllables at the ends of lines) the final syllables of polysyllabic words tend to occur at stronger metrical positions than non-final syllables of those words; it also showed that monosyllabic content words tend to occur at stronger positions than monosyllabic function words. While conflicts between stress and meter are much more common in French than in English vocal music, these results suggest that French poets and composers recognized distinctions of stress between syllables of polysyllabic words and between monosyllabic content and function words.
Binaural hearing ability with mastoid applied bilateral bone conduction stimulation in normal hearing subjects
Authors: Stenfelt Stefan , Zeitooni Mehrnaz
Published: July 2013

The ability to use binaural cues when stimulation was by bilaterally applied bone conduction (BC) transducers was investigated in 20 normal hearing participants. The results with BC stimulation were compared with normal air conduction (AC) stimulation through earphones. The binaural hearing ability was tested by spatial release from masking, binaural intelligibility level difference (BILD), binaural masking level difference (BMLD) using chirp stimulation, and test of the precedence effect. In all tests, the participants revealed a benefit of bilateral BC stimulation indicating use of binaural cues. In the speech based tests, the binaural benefit for BC stimulation was approximately half that with AC stimulation. For the BC BMLD test with chirp stimulation, there were indications of superposition of the ipsilateral and contralateral pathways at the cochlear level affecting the results. The precedence effect test indicated significantly worse results for BC stimulation than for AC stimulation with low-frequency stimulation while they were close for high-frequency stimulation; broad-band stimulation gave results that were slightly worse than the high-frequency results.
Evidence that the Lombard effect is frequency-specific in humans
Authors: Stowe Lauren M. , Golob Edward J.
Published: July 2013

Recent perspectives suggest that the Lombard effect is an increase in the suprasegmental speech parameters of vocal intensity, duration, and fundamental frequency in the presence of noise. It has been viewed as a non-specific response to ambient noise, but this assumption has not been thoroughly tested. Two experiments using healthy adults measured intensity, duration, and F0 changes in broadband (0.2–20 kHz) and notched noise (0.05–4 kHz removed) during a picture naming task. The pilot experiment showed that broadband noise containing speech-similar frequencies significantly increased intensity, duration, and F0 while notched noise, which removed the majority of speech-similar frequencies, had no effect. The main experiment added bandpass noise (0.05–4.0 kHz) which contained a major portion of speech-similar frequencies and was the mirror image of the notched noise. Broadband and notched noise results were replicated. Bandpass noise increased intensity and duration, but to a lesser degree than did broadband noise, and had no effect on F0. Findings show that the Lombard effect is sensitive to frequencies vital for speech and is not a general response to any competing sound in the environment. Implications for suprasegmental control of speech are discussed.