bluuebunny/crossref_metadata_2025 huggingface dataset:
WE‐AB‐206‐00: Diagnostic QA/QC Hands‐On Workshop
Authors: Lu Zhengfeng
Published: July 2016

The involvement of medical physicists in diagnostic ultrasound imaging service is increasing due to QC and accreditation requirements. The goal of this ultrasound hands‐on workshop is to demonstrate quality control (QC) testing in diagnostic ultrasound and to provide updates in ACR ultrasound accreditation requirements. The first half of this workshop will include two presentations reviewing diagnostic ultrasound QA/QC and ACR ultrasound accreditation requirements. The second half of the workshop will include live demonstrations of basic QC tests. An array of ultrasound testing phantoms and ultrasound scanners will be available for attendees to learn diagnostic ultrasound QC in a hands‐on environment with live demonstrations and on‐site instructors. The targeted attendees are medical physicists in diagnostic imaging.

Learning Objectives:

Gain familiarity with common elements of a QA/QC program for diagnostic ultrasound imaging

dentify QC tools available for testing diagnostic ultrasound systems and learn how to use these tools

Learn ACR ultrasound accreditation requirements

Jennifer Walter is an employee of American College of Radiology on Ultrasound Accreditation.
WE‐AB‐206‐03: Workshop
Authors: Lu Z.
Published: July 2016

The involvement of medical physicists in diagnostic ultrasound imaging service is increasing due to QC and accreditation requirements. The goal of this ultrasound hands‐on workshop is to demonstrate quality control (QC) testing in diagnostic ultrasound and to provide updates in ACR ultrasound accreditation requirements. The first half of this workshop will include two presentations reviewing diagnostic ultrasound QA/QC and ACR ultrasound accreditation requirements. The second half of the workshop will include live demonstrations of basic QC tests. An array of ultrasound testing phantoms and ultrasound scanners will be available for attendees to learn diagnostic ultrasound QC in a hands‐on environment with live demonstrations and on‐site instructors. The targeted attendees are medical physicists in diagnostic imaging.

Learning Objectives:

Gain familiarity with common elements of a QA/QC program for diagnostic ultrasound imaging

dentify QC tools available for testing diagnostic ultrasound systems and learn how to use these tools

Learn ACR ultrasound accreditation requirements

Jennifer Walter is an employee of American College of Radiology on Ultrasound Accreditation.
WE‐D‐204‐01: Site‐Specific Clinical Rotation: Into the Minds of the Radiation Oncologists
Authors: Hendrickson K.
Published: July 2016

Speakers in this session will present overview and details of a specific rotation or feature of their Medical Physics Residency Program that is particularly exceptional and noteworthy. The featured rotations include foundational topics executed with exceptional acumen and innovative educational rotations perhaps not commonly found in Medical Physics Residency Programs. A site‐specific clinical rotation will be described, where the medical physics resident follows the physician and medical resident for two weeks into patient consultations, simulation sessions, target contouring sessions, planning meetings with dosimetry, patient follow up visits, and tumor boards, to gain insight into the thought processes of the radiation oncologist. An incident learning rotation will be described where the residents learns about and practices evaluating clinical errors and investigates process improvements for the clinic. The residency environment at a Canadian medical physics residency program will be described, where the training and interactions with radiation oncology residents is integrated. And the first month rotation will be described, where the medical physics resident rotates through the clinical areas including simulation, dosimetry, and treatment units, gaining an overview of the clinical flow and meeting all the clinical staff to begin the residency program. This session will be of particular interest to residency programs who are interested in adopting or adapting these curricular ideas into their programs and to residency candidates who want to learn about programs already employing innovative practices.

Learning Objectives:

To learn about exceptional and innovative clinical rotations or program features within existing Medical Physics Residency Programs.

To understand how to adopt/adapt innovative curricular designs into your own Medical Physics Residency Program, if appropriate.
WE‐DE‐201‐03: Combined Use of 192Ir, 60Co, and 169Yb Sources with the Novel Direction Modulated Brachytherapy Tandem Applicator for High Dose Rate Brachytherapy Planning of Cervical Cancer
Authors: Safigholi H , Han D , Mashouf S , Soliman A , Meigooni A S , Owrangi A , Song W Y
Published: July 2016

Purpose:

To evaluate the improvement in plan quality when various combinations of 192Ir, 60Co, and 169Yb sources are used in combination with a novel direction modulated brachytherapy (DMBT) tandem applicator for high dose rate brachytherapy of cervical cancer.

Methods:

The proposed DMBT tandem applicator is designed for image‐guided adaptive brachytherapy (IGABT), especially MRI, of cervical cancer. It has 6 peripheral holes of 1.3‐mm width, grooved along a 5.4‐mm diameter nonmagnetic tungsten alloy rod of density 18.0 g/cc, capable of generating directional dose profiles ‐ leading to enhanced dose sculpting capacity through inverse planning. Monte Carlo simulations of the three HDR sources individually inside the DMBT applicator were performed and imported into an in‐house developed inverse optimization code. We then performed inverse planning with 14 cervical cancer patients enrolled in EMBRACE study. In all patients, 3D MRI‐based planning was performed while utilizing 1) tandem‐ring and needles attached‐to‐ring (7 patients) and 2) tandem‐ring and needles both attached‐to‐ring and free‐hand‐loaded (7 patients), in accordance with the GEC‐ESTRO recommendations. All plans were normalized to receive the same HRCTV D90 and DVH parameters were evaluated.

Results:

The DMBT tandem was used in all cases. Overall, the combined use of two sources (192Ir‐60Co and 192Ir‐169Yb, but not 60Co‐169Yb) generally produced better quality plans than with the 192Ir source alone in terms of sparing OARs. For example, up to 3.5, 4.4, and 3.9% individual reductions in D2cc were observed for the bladder, rectum, and sigmoid, respectively, between 192Ir‐60Co and 192Ir‐only plans for patient cases in #1. While up to 5.5, 2.0, and 5.7% individual reductions were observed for patient cases in #2.

Conclusion:

We have demonstrated that, in addition to “directional modulation” of DMBT, use of multiple sources with sufficient differences in energy can be utilized to achieve additional improvement in plan quality for IGABT of cervical cancer.
WE‐DE‐201‐08: Multi‐Source Rotating Shield Brachytherapy Apparatus for Prostate Cancer
Authors: Dadkhah H , Wu X , Kim Y , Flynn R
Published: July 2016

Purpose:

To introduce a novel multi‐source rotating shield brachytherapy (RSBT) apparatus for the precise simultaneous angular and linear positioning of all partially‐shielded 153Gd radiation sources in interstitial needles for treating prostate cancer. The mechanism is designed to lower the detrimental dose to healthy tissues, the urethra in particular, relative to conventional high‐dose‐rate brachytherapy (HDR‐BT) techniques.

Methods:

Following needle implantation, the delivery system is docked to the patient template. Each needle is coupled to a multi‐source afterloader catheter by a connector passing through a shaft. The shafts are rotated by translating a moving template between two stationary templates. Shaft walls as well as moving template holes are threaded such that the resistive friction produced between the two parts exerts enough force on the shafts to bring about the rotation. Rotation of the shaft is then transmitted to the shielded source via several keys. Thus, shaft angular position is fully correlated with the position of the moving template. The catheter angles are simultaneously incremented throughout treatment as needed, and only a single 360° rotation of all catheters is needed for a full treatment. For each rotation angle, source depth in each needle is controlled by a multi‐source afterloader, which is proposed as an array of belt‐driven linear actuators, each of which drives a source wire.

Results:

Optimized treatment plans based on Monte Carlo dose calculations demonstrated RSBT with the proposed apparatus reduced urethral D1cc below that of conventional HDR‐BT by 35% for urethral dose gradient volume within 3 mm of the urethra surface. Treatment time to deliver 20 Gy with multi‐source RSBT apparatus using nineteen 62.4 GBq 153Gd sources is 117 min.

Conclusions:

The proposed RSBT delivery apparatus in conjunction with multiple nitinol catheter‐mounted platinum‐shielded 153Gd sources enables a mechanically feasible urethra‐sparing treatment technique for prostate cancer in a clinically reasonable timeframe.
WE‐D‐BRB‐03: Current State of Volumetric Image Guidance for Proton Therapy
Authors: Hua C.
Published: July 2016

The goal of this session is to review the physics of proton therapy, treatment planning techniques, and the use of volumetric imaging in proton therapy. The course material covers the physics of proton interaction with matter and physical characteristics of clinical proton beams. It will provide information on proton delivery systems and beam delivery techniques for double scattering (DS), uniform scanning (US), and pencil beam scanning (PBS). The session covers the treatment planning strategies used in DS, US, and PBS for various anatomical sites, methods to address uncertainties in proton therapy and uncertainty mitigation to generate robust treatment plans. It introduces the audience to the current status of image guided proton therapy and clinical applications of CBCT for proton therapy. It outlines the importance of volumetric imaging in proton therapy.

Learning Objectives:

Gain knowledge in proton therapy physics, and treatment planning for proton therapy including intensity modulated proton therapy.

The current state of volumetric image guidance equipment in proton therapy.

Clinical applications of CBCT and its advantage over orthogonal imaging for proton therapy.

B. Teo, B.K Teo had received travel funds from IBA in 2015.
WE‐DE‐BRA‐02: BEST IN PHYSICS (JOINT IMAGING‐THERAPY): Prototype for An In‐Room Supercompounded 3D Volumetric Ultrasound Image Guidance System for Prone Breast SBRT
Authors: Chiu T , Zhang Y , Hrycushko B , Zhao B , Chopra R , Jiang S , Gu X
Published: July 2016

Purpose:

SBRT requires both substantial positioning precision and accuracy. However, accurate dose delivery is challenging for prone breast SBRT due to breast deformation, lumpectomy cavity shrinkage and ineffective CT/CBCT on soft tissue. We developed a prototype in‐room 3D volumetric ultrasound (US) image guidance system for prone breast SBRT.

Methods:

The designed system, set beneath a prone breast board, consists of a customized breast cup, rotational scanning water container, and a portable US scanner. The breast CT scan is converted to STereoLithographic model then 3D printed as a mold to construct a patient‐specific breast cup. The holder is fabricated with liquid urethane resin and cured to a ∼1 mm thick semi‐rigid polymerized cup. The US transducer is attached to the container but separated from a water compartment by a urethane resin membrane. The transverse scan is acquired by simultaneously rotating the water container and transducer every 5°. The 3D US image is constructed with multiple transverse images using a supercompounding‐technique‐based volumetric US reconstruction algorithm. The performance of the prototype US system was evaluated on a gelatin based breast phantom with five embedded reflective markers. Reconstructed image quality (size and geometric accuracy) was compared with MRI images of the same phantom.

Results:

In the evaluated plane, the five embedded markers were compared to MRI in terms of size and location. Diameter differences were 1.85, 1.71, 2.37, 1.00 and 1.85 mm between MRI and US. The 1–2 mm variations come from the different edge response the material has on the two imaging modalities. The difference in distance between adjacent marker centers between MRI and US were 0.57, 0.84, 0.75 and 0.80 mm.

Conclusion:

The phantom study results show geometric agreement between MRI and US indicating that the proposed image‐guidance system can provide precise and accurate patient setup for each SBRT fraction.

CPRIT Grant R1308
WE‐DE‐BRA‐04: A Cost‐Effective Pixelated EPID Scintillator for Enhanced Contrast and DQE
Authors: Rottmann J , Myronakis M , Hu Y , Shedlock D , Wang A , Humber D , Morf D , Fueglistaller R , Star‐Lack J , Berbeco R
Published: July 2016

Purpose:

Beams‐eye‐view imaging applications such as real‐time soft‐tissue motion estimation and MV‐CBCT are hindered by the inherently low image contrast of electronic portal imaging devices (EPID) currently in clinical use. We investigate a cost effective scintillating glass that provides substantially increased detective quantum efficiency (DQE) and contrast to noise ratio (CNR).

Methods:

A pixelated scintillator prototype was built from LKH‐5 glass. The array is 12mm thick; 42.4×42.4cm2 wide and features 1.51mm pixel pitch with 20µm separation (glue+septa). The LKH‐5 array was mounted on the active matrix flat panel imager (AMPFI) of an AS‐1200 (Varian) with the GdO2S2:Tb removed. A second AS‐1200 was utilized as reference detector. The prototype EPID was characterized in terms of CNR, modulation transfer function (MTF) and DQE. Additionally, the visibility of various fiducial markers typically used in the clinic as well as a realistic 3D‐printed lung tumor model was assessed. All items were placed in a 12cm thick solid water phantom. CNR is estimated using a Las Vegas contrast phantom, presampled MTF is estimated using a slanted slit technique and the DQE is calculated from measured normalized noise power spectra (NPS) and the MTF.

Results:

DQE(0) for the LKH‐5 prototype increased by a factor of 8× to about 10%, compared to the AS‐1200 equipped with its standard GdO2S2:Tb scintillator. CNR increased by a factor of 5.3×. Due to the pixel size the MTF50 decreased by about 55% to 0.23lp/mm. The visibility of all fiducial markers as well as the tumor model were however markedly improved in comparison to an acquisition with the same parameters using the GdO2S2:Tb scintillator.

Conclusion:

LKH‐5 scintillating glasses allow the cost effective construction of thick pixelated scintillators for portal imaging which can yield a substantial increase in DQE and CNR. Soft tissue and fiducial marker visibility was found to be markedly improved.

The project was supported in part by NIH grant R01CA188446‐01 and a grant from Varian Medical Systems.
WE‐DE‐202‐00: Connecting Radiation Physics with Computational Biology
Authors: Schuemann Jan
Published: July 2016

Radiation therapy for the treatment of cancer has been established as a highly precise and effective way to eradicate a localized region of diseased tissue. To achieve further significant gains in the therapeutic ratio, we need to move towards biologically optimized treatment planning. To achieve this goal, we need to understand how the radiation‐type dependent patterns of induced energy depositions within the cell (physics) connect via molecular, cellular and tissue reactions to treatment outcome such as tumor control and undesirable effects on normal tissue.

Several computational biology approaches have been developed connecting physics to biology. Monte Carlo simulations are the most accurate method to calculate physical dose distributions at the nanometer scale, however simulations at the DNA scale are slow and repair processes are generally not simulated. Alternative models that rely on the random formation of individual DNA lesions within one or two turns of the DNA have been shown to reproduce the clusters of DNA lesions, including single strand breaks (SSBs), double strand breaks (DSBs) without the need for detailed track structure simulations. Efficient computational simulations of initial DNA damage induction facilitate computational modeling of DNA repair and other molecular and cellular processes. Mechanistic, multiscale models provide a useful conceptual framework to test biological hypotheses and help connect fundamental information about track structure and dosimetry at the sub‐cellular level to dose‐response effects on larger scales.

In this symposium we will learn about the current state of the art of computational approaches estimating radiation damage at the cellular and sub‐cellular scale. How can understanding the physics interactions at the DNA level be used to predict biological outcome? We will discuss if and how such calculations are relevant to advance our understanding of radiation damage and its repair, or, if the underlying biological processes are too complex for a mechanistic approach. Can computer simulations be used to guide future biological research? We will debate the feasibility of explaining biology from a physicists’ perspective.

Learning Objectives:

Understand the potential applications and limitations of computational methods for dose‐response modeling at the molecular, cellular and tissue levels

Learn about mechanism of action underlying the induction, repair and biological processing of damage to DNA and other constituents

Understand how effects and processes at one biological scale impact on biological processes and outcomes on other scales

J. Schuemann, NCI/NIH grantsS. McMahon, Funding: European Commission FP7 (grant EC FP7 MC‐IOF‐623630)
WE‐DE‐209‐04: 3D Surface Image‐Guided
Authors: Tang X.
Published: July 2016

Breast radiation therapy is associated with some risk of lung toxicity as well as cardiac toxicity for left‐sided cases. Radiation doses to the lung and heart can be reduced by using the deep inspiration breath hold (DIBH) technique, in which the patient is simulated and treated during the deep inspiration phase of the breathing cycle. During DIBH, the heart is usually displaced posteriorly, inferiorly, and to the right, effectively expanding the distance between the heart and the breast/chest wall. As a result, the distance between the medial treatment field border and heart/lung is increased. Also, in a majority of DIBH patients, the air drawn into the thoracic cavity increases the total lung volume.

The DIBH was discussed by an AAPM Task Group 10 years ago in the AAPM TG 76 report. However, DIBH is still not the standard of care in many clinics, which may be partially due to challenges associated with its implementation. Therefore, this seccion will focus primarily on how to clinically implement four different DIBH techniques: (1) Active Breathing Control, (2) Spirometric Motion Management, (3) 3D Surface Image‐Guided, and (4) Self‐held Breath Control with Respiratory Monitoring and Feedback Guidance.

Learning Objectives:

Describe the physical displacement of the heart and the change in lung volume during DIBH and discuss dosimetric consequences of those changes.

Provide an overview of the technical aspects.

Describe work flow for patient simulation and treatment.

Give an overview of commissioning and routine.

Provide practical tips for clinical implementation.
WE‐DE‐206‐00: MRI Physics
Authors: Shu Yunhong
Published: July 2016

Magnetic resonance imaging (MRI) has become an essential part of clinical imaging due to its ability to render high soft tissue contrast. Instead of ionizing radiation, MRI use strong magnetic field, radio frequency waves and field gradients to create diagnostic useful images. It can be used to image the anatomy and also functional and physiological activities within the human body. Knowledge of the basic physical principles underlying MRI acquisition is vitally important to successful image production and proper image interpretation.

This lecture will give an overview of the spin physics, imaging principle of MRI, the hardware of the MRI scanner, and various pulse sequences and their applications. It aims to provide a conceptual foundation to understand the image formation process of a clinical MRI scanner.

Learning Objectives:

Understand the origin of the MR signal and contrast from the spin physics level.

Understand the main hardware components of a MRI scanner and their purposes

Understand steps for MR image formation including spatial encoding and image reconstruction

Understand the main kinds of MR pulse sequences and their characteristics.
WE‐DE‐207B‐02: Detection of Masses On Mammograms Using Deep Convolutional Neural Network: A Feasibility Study
Authors: Suzuki S , Zhang X , Homma N , Ichiji K , Kawasumi Y , Ishibashi T , Yoshizawa M
Published: July 2016

Purpose:

To develop a deep convolutional neural network (DCNN)‐based computer‐aided diagnosis (CAD) system for detecting the masses in digital mammographic images.

Methods:

A DCNN architecture, which consists of 5 convolutional layers and 3 fully connected layers, is constructed in this study. The DCNN parameters are then trained by the following two procedures. We first train the DCNN using about 1.3 million natural images for classification of 1,000 categories. Then, we modify the last fully connected layer and subsequently train the modified DCNN using 1,656 mammographic region of interest (ROI) images for two categories classification: mass and normal.

Results:

The trained DCNN is tested by using 198 mammographic ROI images including 99 mass images and 99 normal images. The experimental results show that the sensitivity of the mass detection is about 89.9% and the false positive is 19.2%. These results demonstrated that the DCNN has a potential for mammographic CAD.

Conclusion:

In recent years, the DCNN, as one of the most successful techniques in deep learning technology, made a remarkable impact on image recognition application. For medical image recognition, however, its performance is uncertainty because collecting a large amount of training image data for a particularly medical image modality is difficult. In this study, our preliminary experiments demonstrated a feasibility to apply the DCNN in mammographic CAD system. To the best of our knowledge, this study is also the first demonstration of DCNN for detecting the masses in mammographic images.
WE‐DE‐207B‐05: Measuring Spatial Resolution in Digital Breast Tomosynthesis: Update of AAPM Task Group 245
Authors: Scaduto DA , Goodsitt M , Chan H‐P , Olafsdottir H , Das M , Fredenberg E , Geiser W , Goodenough D , Heid P , Hu Y‐H , Liu B , Mainprize J , Reiser I , Van Engen R , Varchena V , Vecchio S , Glick S , Zhao W
Published: July 2016

Purpose:

Spatial resolution in digital breast tomosynthesis (DBT) is affected by inherent/binned detector resolution, oblique entry of x‐rays, and focal spot size/motion; the limited angular range further limits spatial resolution in the depth‐direction. While DBT is being widely adopted clinically, imaging performance metrics and quality control protocols have not been standardized. AAPM Task Group 245 on Tomosynthesis Quality Control has been formed to address this deficiency.

Methods:

Methods of measuring spatial resolution are evaluated using two prototype quality control phantoms for DBT. Spatial resolution in the detector plane is measured in projection and reconstruction domains using edge‐spread function (ESF), point‐spread function (PSF) and modulation transfer function (MTF). Spatial resolution in the depth‐direction and effective slice thickness are measured in the reconstruction domain using slice sensitivity profile (SSP) and artifact spread function (ASF). An oversampled PSF in the depth‐direction is measured using a 50 µm angulated tungsten wire, from which the MTF is computed. Object‐dependent PSF is derived and compared with ASF. Sensitivity of these measurements to phantom positioning, imaging conditions and reconstruction algorithms is evaluated. Results are compared from systems of varying acquisition geometry (9–25 projections over 15–60°). Dependence of measurements on feature size is investigated.

Results:

Measurements of spatial resolution using PSF and LSF are shown to depend on feature size; depth‐direction spatial resolution measurements are shown to similarly depend on feature size for ASF, though deconvolution with an object function removes feature size‐dependence. A slanted wire may be used to measure oversampled PSFs, from which MTFs may be computed for both in‐plane and depth‐direction resolution.

Conclusion:

Spatial resolution measured using PSF is object‐independent with sufficiently small object; MTF is object‐independent. Depth‐direction spatial resolution may be measured directly using MTF or indirectly using ASF or SSP as surrogate measurements. While MTF is object‐independent, it is invalid for nonlinear reconstructions.
WE‐DE‐207B‐11: Implementation of Size‐Specific 3D Beam Modulation Filters On a Dedicated Breast CT Platform Using Breast Immobilization
Authors: Hernandez A , Boone J
Published: July 2016

Purpose:

To implement a 3D beam modulation filter (3D‐BMF) in dedicated breast CT (bCT) and develop a method for conforming the patient's breast to a pre‐defined shape, optimizing the effects of the filter. This work expands on previous work reporting the methodology for designing a 3D‐BMF that can spare unnecessary dose and improve signal equalization at the detector by preferentially filtering the beam in the thinner anterior and peripheral breast regions.

Methods:

Effective diameter profiles were measured for 219 segmented bCT images, grouped into volume quintiles, and averaged within each group to represent the range of breast sizes found clinically. These profiles were then used to generate five size‐specific computational phantoms and fabricate five size‐specific UHMW phantoms. Each computational phantom was utilized for designing a size‐specific 3D‐BMF using previously reported methods. Glandular dose values and projection images were simulated in MCNP6 with and without the 3DBMF using the system specifications of our prototype bCT scanner “Doheny”. Lastly, thermoplastic was molded around each of the five phantom sizes and used to produce a series of breast immobilizers for use in conforming the patient's breast during bCT acquisition.

Results:

After incorporating the 3D‐BMF, MC simulations estimated an 80% average reduction in the detector dynamic range requirements across all phantom sizes. The glandular dose was reduced on average 57% after normalizing by the number of quanta reaching the detector under the thickest region of the breast.

Conclusion:

A series of bCT‐derived breast phantoms were used to design size‐specific 3D‐BMFs and breast immobilizers that can be used on the bCT platform to conform the patient's breast and therefore optimally exploit the benefits of the 3D‐BMF. Current efforts are focused on fabricating several prototype 3D‐BMFs and performing phantom scans on Doheny for MC simulation validation and image quality analysis.

Research reported in this paper was supported in part by the National Cancer Institute of the National Institutes of Health under award R01CA181081. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institue of Health.
WE‐FG‐206‐07: Assessing the Lung Function of Patients with Non‐Small Cell Lung Cancer Using Hyperpolarized Xenon‐129 Dissolved‐Phase MRI
Authors: Qing K , Mugler J , Chen Q
Published: July 2016

Purpose:

Hyperpolarized xenon‐129 dissolved‐phase MRI is the first imaging technique that allows 3‐dimensional regional mapping of ventilation and gas uptake by tissue and blood the in human lung. Multiple outcome measures can be produced from this method. Existing studies in subjects with major lung diseases compared to healthy controls demonstrated high sensitivities of this method to pulmonary physiological factors including ventilation, alveolar tissue density, surface‐to‐volume ratio, pulmonary perfusion and gas‐blood barrier thickness. The purpose of this study is to evaluate the utility of this new imaging tool to assess the lung function in patients with non‐small cell lung cancer (NSCLC).

Methods:

Ten healthy controls (age: 63±10) and five patients (age: 62±13) with NSCLC underwent the xenon‐129 dissolved‐phase MRI, pulmonary function test (PFT) and CT for clinical purpose. Three outcome measures were produced from xenon‐129 dissolved‐phase MRI, including ventilation defect fraction (Vdef%) reflecting the airflow obstruction, tissue‐to‐gas ratio reflecting lung tissue density, and RBC‐to‐tissue ratio reflecting pulmonary perfusion and gas exchange.

Results:

Compared to healthy controls, patients with NSCLC showed more ventilation defects (NSCLC: 22±6%; control: 40±18%; P=0.01), lower tissue‐to‐gas (NSCLC: 0.82±0.31%; control: 1.07±0.13%; P=0.05) and RBC‐to‐tissue ratios (NSCLC: 0.82±0.31%; control: 1.07±0.13%; P=0.01). Maps for ventilation and gas uptake by tissue and blood were highly heterogeneous in the lungs of patients. Vdef% and RBC‐to‐tissue ratios in all 15 subjects correlated with corresponding global lung functional measures from PFT: FEV1/FVC (R=−0.91, P<0.001) and DLCO % predicted (R=0.54, P=0.03), respectively. The tissue‐to‐gas ratios correlated with tissue density (HU) measured by CT (R=0.88, P<0.001).

Conclusion:

With the unique ability to provide detailed information about lung function including ventilation, tissue density, perfusion and gas exchange with 3D resolution, hyperpolarized xenon‐129 dissolved‐phase MRI has high potential to be used as an important reference for radiotherapy treatment planning and for evaluating the side effects of the treatment.

Receive research support and funding from Siemens.
WE‐FG‐206‐08: Pulmonary Functional Imaging Biomarkers of NSCLC to Guide and Optimize Functional Lung Avoidance Radiotherapy
Authors: Sheikh Khadija , Capaldi Dante PI , Hoover Douglas A , Palma David A , Yaremko Brian P , Parraga Grace
Published: July 2016

Purpose:

Functional lung avoidance radiotherapy promises optimized therapy planning by minimizing dose to well‐functioning lung and maximizing dose to the rest of the lung. Patients with NSCLC commonly present with co‐morbid COPD and heterogeneously distributed ventilation abnormalities stemming from emphysema, airways disease, and tumour burden. We hypothesized that pulmonary functional imaging methods may be used to optimize radiotherapy plans to avoid regions of well‐functioning lung and significantly improve outcomes like quality‐of‐life and survival. To ascertain the utility of functional lung avoidance therapy in clinical practice, we measured COPD phenotypes in NSCLC patients enrolled in a randomized‐controlled‐clinical‐trial prior to curative intent therapy.

Methods:

Thirty stage IIIA/IIIB NSCLC patients provided written informed consent to a randomized‐controlled‐clinical‐trial (https://clinicaltrials.gov/ct2/show/NCT02002052) comparing outcomes in patients randomized to standard or image‐guided radiotherapy. Hyperpolarized noble gas MRI ventilation‐defect‐percent (VDP) (Kirby et al, Acad Radiol, 2012) as well as CT‐emphysema measurements were determined. Patients were stratified based on quantitative imaging evidence of ventilation‐defects and emphysema into two subgroups: 1) tumour‐specific ventilation defects only (TSD), and, 2) tumour‐specific and other ventilation defects with and without emphysema (TSDVE). Receiver‐operating‐characteristic (ROC) curves were used to characterize the performance of clinical measures as predictors of the presence of non‐tumour specific ventilation defects.

Results:

Twenty‐one out of thirty subjects (70%) had non‐tumour specific ventilation defects (TSDVE) and nine subjects had ONLY tumour‐specific defects (TSD). Subjects in the TSDVE group had significantly greater smoking‐history (p=.006) and airflow obstruction (FEV1/FVC) (p=.001). ROC analysis demonstrated an 87% classification rate for smoking pack‐years, 90% for FEV1/FVC, and 56% for tumour RECIST measurements for identifying patients with non‐tumour and tumour‐specific ventilation abnormalities.

Conclusion:

70% of NSCLC patients had ventilation abnormalities stemming from emphysema, airways disease and tumour burden. Smoking‐history and airflow obstruction, but not RECIST, identified NSCLC patients with ventilation abnormalities appropriate for functional lung avoidance therapy.
WE‐FG‐206‐10: Portal Venous Perfusion Quantitation From Liver DCE‐MRI by Voxel Uptake Curve Clustering and Input Function Normalization
Authors: Johansson A , Balter J , Feng M , Cao Y
Published: July 2016

Purpose:

Portal venous perfusion (PV) quantified from liver DCE‐MRI by a dual‐input single‐compartment model is sensitive to errors in the PV input function (PVIF) due to partial volume effect and respiratory motion. To improve repeatability of the local PV perfusion estimate and reduce computation complexity, we developed and evaluated an approach that combines dynamic curve clustering and parameter estimation with normalization of the PVIF.

Methods:

The PVIF and arterial input function (AIF), after initial transient behaviors, should reach a state where the contrast concentrations in both blood pools are the same. The PVIF was therefore rescaled such that its tail matched that of the AIF. Also, to reduce the motion effect on the PV perfusion images, voxels with similar contrast uptake curves were pooled together by a clustering algorithm, and then the perfusion parameters of the dynamic curves of the cluster centers were estimated. Perfusion maps were created based upon probabilities of a voxel belonging to the clusters and the perfusion parameters of the clusters. The proposed method was evaluated for repeatability of local PV perfusion in normal tissue for 8 patients with repeated examinations, and by the Pearson correlation coefficient of mean PV perfusion of the whole liver to an independent global liver function measure using ICG clearance rate analyzed over 89 examinations.

Results:

The average PV perfusion RMSE of the repeated measurements was reduced from 52.4 by the conventional voxelwise estimation to 33.7 ml/(100 ml*min) by the proposed method. Similarly, the correlation coefficient of the total perfusion to ICG clearance rate was increased from 0.21 to 0.46 by the new method.

Conclusion:

This technique shows promise in improving repeatability of PV perfusion from DCE‐MRI of the liver. Future developments have the potential to further reduce systematic and random errors in the PV perfusion quantification, and computational complexity.

NIH RO1 CA132834, NIH PO1 CA59827
WE‐FG‐207B‐02: Material Reconstruction for Spectral Computed Tomography with Detector Response Function
Authors: Liu J , Gao H
Published: July 2016

Purpose:

Different from the conventional computed tomography (CT), spectral CT based on energy‐resolved photon‐counting detectors is able to provide the unprecedented material composition. However, an important missing piece for accurate spectral CT is to incorporate the detector response function (DRF), which is distorted by factors such as pulse pileup and charge‐sharing. In this work, we propose material reconstruction methods for spectral CT with DRF.

Methods:

The polyenergetic X‐ray forward model takes the DRF into account for accurate material reconstruction. Two image reconstruction methods are proposed: a direct method based on the nonlinear data fidelity from DRF‐based forward model; a linear‐data‐fidelity based method that relies on the spectral rebinning so that the corresponding DRF matrix is invertible. Then the image reconstruction problem is regularized with the isotropic TV term and solved by alternating direction method of multipliers.

Results:

The simulation results suggest that the proposed methods provided more accurate material compositions than the standard method without DRF. Moreover, the proposed method with linear data fidelity had improved reconstruction quality from the proposed method with nonlinear data fidelity.

Conclusion:

We have proposed material reconstruction methods for spectral CT with DRF, whichprovided more accurate material compositions than the standard methods without DRF. Moreover, the proposed method with linear data fidelity had improved reconstruction quality from the proposed method with nonlinear data fidelity.

Jiulong Liu and Hao Gao were partially supported by the NSFC (#11405105), the 973 Program (#2015CB856000), and the Shanghai Pujiang Talent Program (#14PJ1404500).
WE‐FG‐207B‐03: Multi‐Energy CT Reconstruction with Spatial Spectral Nonlocal Means Regularization
Authors: Li B , Shen C , Ouyang L , Yang M , Zhou L , Jiang S , Jia X
Published: July 2016

Purpose:

Multi‐energy computed tomography (MECT) is an emerging application in medical imaging due to its ability of material differentiation and potential for molecular imaging. In MECT, image correlations at different spatial and channels exist. It is desirable to incorporate these correlations in reconstruction to improve image quality. For this purpose, this study proposes a MECT reconstruction technique that employes spatial spectral non‐local means (ssNLM) regularization.

Methods:

We consider a kVp‐switching scanning method in which source energy is rapidly switched during data acquisition. For each energy channel, this yields projection data acquired at a number of angles, whereas projection angles among channels are different. We formulate the reconstruction task as an optimziation problem. A least square term enfores data fidelity. A ssNLM term is used as regularization to encourage similarities among image patches at different spatial locations and channels. When comparing image patches at different channels, intensity difference were corrected by a transformation estimated via histogram equalization during the reconstruction process.

Results:

We tested our method in a simulation study with a NCAT phantom and an experimental study with a Gammex phantom. For comparison purpose, we also performed reconstructions using conjugate‐gradient least square (CGLS) method and conventional NLM method that only considers spatial correlation in an image. ssNLM is able to better suppress streak artifacts. The streaks are along different projection directions in images at different channels. ssNLM discourages this dissimilarity and hence removes them. True image structures are preserved in this process. Measurements in regions of interests yield 1.1 to 3.2 and 1.5 to 1.8 times higher contrast to noise ratio than the NLM approach. Improvements over CGLS is even more profound due to lack of regularization in the CGLS method and hence amplified noise.

Conclusion:

The proposed ssNLM method for kVp‐switching MECT reconstruction can achieve high quality MECT images.
WE‐FG‐207B‐06: Plaque Composition Measurement with Dual Energy Computed Tomography
Authors: Wang C , Ding H , Malkasian S , Molloi S
Published: July 2016

Purpose:

To investigate the feasibility of characterizing arterial plaque composition in terms of water, lipid and protein or calcium using dual energy computed tomography. Characterization of plaque composition can potentially help distinguish vulnerable from stable plaques.

Methods:

Simulations studies were performed by the CT simulator based on ASTRA tomography toolbox. The beam energy for dual energy images was selected to be 80 kVp and 135 kVp. The radiation dose and energy spectrum for the CT simulator were carefully calibrated with respect to a 320‐slice CT scanner. A digital chest phantom was constructed using Matlab for calibration and plaque measurement. Pure water, lipid, protein or calcium was used for calibration and a mixture of different volume percentages of these materials were used for validation purposes. Non‐calcified plaque was simulated using water, lipid and protein with volumetric percentage range of 35%∼65%, 5%∼60% and 5%∼40%, respectively. Calcified plaque was simulated using water, lipid and calcium with volumetric percentage range of 50%∼80%, 8%∼45% and 3%∼13%, respectively. We employed iterative sinogram processing (ISP) to reduce the beam hardening effect in the simulation to improve the decomposition results.

Results:

The simulated known composition and dual energy decomposition results were in good agreement. Water, lipid and protein (calcium) mixtures were decomposed into water, lipid and protein (calcium) contents. The RMS errors of volumetric percentage for the water, lipid and protein (non‐calcified plaque) decomposition, as compared to known values, were estimated to be approximately 5.74%, 2.54%, and 0.95% respectively. The RMS errors of volumetric percentage for the water, lipid and Calcium (calcified plaque) decomposition, as compared to known values, were estimated to be approximately 7.4%, 8.64%, and 0.08% respectively.

Conclusion:

The results of this study suggest that the dual energy decomposition can potentially be used to quantify the water, lipid, and protein or calcium composition of a plaque with relatively good accuracy.

Grant funding from Toshiba Medical Systems and Philips Medical Systems
WE‐H‐BRB‐00: Big Data in Radiation Oncology
Authors: Benedict Stanley
Published: July 2016

Big Data in Radiation Oncology: (1) Overview of the NIH 2015 Big Data Workshop, (2) Where do we stand in the applications of big data in radiation oncology?, and (3) Learning Health Systems for Radiation Oncology: Needs and Challenges for Future Success

The overriding goal of this trio panel of presentations is to improve awareness of the wide ranging opportunities for big data impact on patient quality care and enhancing potential for research and collaboration opportunities with NIH and a host of new big data initiatives.

This presentation will also summarize the Big Data workshop that was held at the NIH Campus on August 13–14, 2015 and sponsored by AAPM, ASTRO, and NIH. The workshop included discussion of current Big Data cancer registry initiatives, safety and incident reporting systems, and other strategies that will have the greatest impact on radiation oncology research, quality assurance, safety, and outcomes analysis.

Learning Objectives:

To discuss current and future sources of big data for use in radiation oncology research

To optimize our current data collection by adopting new strategies from outside radiation oncology

To determine what new knowledge big data can provide for clinical decision support for personalized medicine

L. Xing, NIH/NCI Google Inc.
WE‐H‐BRB‐01: Overview of the ASTRO‐NIH‐AAPM 2015 Workshop On Exploring Opportunities for Radiation Oncology in the Era of Big Data
Authors: Benedict S.
Published: July 2016

Big Data in Radiation Oncology: (1) Overview of the NIH 2015 Big Data Workshop, (2) Where do we stand in the applications of big data in radiation oncology?, and (3) Learning Health Systems for Radiation Oncology: Needs and Challenges for Future Success

The overriding goal of this trio panel of presentations is to improve awareness of the wide ranging opportunities for big data impact on patient quality care and enhancing potential for research and collaboration opportunities with NIH and a host of new big data initiatives.

This presentation will also summarize the Big Data workshop that was held at the NIH Campus on August 13–14, 2015 and sponsored by AAPM, ASTRO, and NIH. The workshop included discussion of current Big Data cancer registry initiatives, safety and incident reporting systems, and other strategies that will have the greatest impact on radiation oncology research, quality assurance, safety, and outcomes analysis.

Learning Objectives:

To discuss current and future sources of big data for use in radiation oncology research

To optimize our current data collection by adopting new strategies from outside radiation oncology

To determine what new knowledge big data can provide for clinical decision support for personalized medicine

L. Xing, NIH/NCI Google Inc.
WE‐H‐BRB‐02: Where Do We Stand in the Applications of Big Data in Radiation Oncology?
Authors: Xing L.
Published: July 2016

Big Data in Radiation Oncology: (1) Overview of the NIH 2015 Big Data Workshop, (2) Where do we stand in the applications of big data in radiation oncology?, and (3) Learning Health Systems for Radiation Oncology: Needs and Challenges for Future Success

The overriding goal of this trio panel of presentations is to improve awareness of the wide ranging opportunities for big data impact on patient quality care and enhancing potential for research and collaboration opportunities with NIH and a host of new big data initiatives.

This presentation will also summarize the Big Data workshop that was held at the NIH Campus on August 13–14, 2015 and sponsored by AAPM, ASTRO, and NIH. The workshop included discussion of current Big Data cancer registry initiatives, safety and incident reporting systems, and other strategies that will have the greatest impact on radiation oncology research, quality assurance, safety, and outcomes analysis.

Learning Objectives:

To discuss current and future sources of big data for use in radiation oncology research

To optimize our current data collection by adopting new strategies from outside radiation oncology

To determine what new knowledge big data can provide for clinical decision support for personalized medicine

L. Xing, NIH/NCI Google Inc.
WE‐H‐BRA‐01: BEST IN PHYSICS (THERAPY): Nano‐Dosimetric Kinetic Model for Variable Relative Biological Effectiveness of Proton and Ion Beams
Authors: Abolfath R , Bronk L , Helo Y , Schuemann J , Titt U. , Grosshans D , Mohan R
Published: July 2016

Purpose:

Recent clonogenic cell survival and γH2AX studies suggest proton relative biological effectiveness (RBE) may be a non‐linear function of linear energy transfer (LET) in the distal edge of the Bragg peak and beyond. We sought to develop a multiscale model to account for non‐linear response phenomena to aid in the optimization of intensity‐modulated proton therapy.

Methods:

The model is based on first‐principle simulations of proton track structures, including secondary ions, and an analytical derivation of the dependence on particle LET of the linear‐quadratic (LQ) model parameters α and β. The derived formulas are an extension of the microdosimetric kinetic (MK) model that captures dissipative track structures and non‐Poissonian distribution of DNA damage at the distal edge of the Bragg peak and beyond. Monte Carlo simulations were performed to confirm the non‐linear dose‐response characteristics arising from the non‐Poisson distribution of initial DNA damage.

Results:

In contrast to low LET segments of the proton depth dose, from the beam entrance to the Bragg peak, strong deviations from non‐dissipative track structures and Poisson distribution in the ionization events in the Bragg peak distal edge govern the non‐linear cell response and result in the transformation α=(1+c_1 L) α_x+2(c_0 L+c_2 L^2)(1+c_1 L) β_x and β=(1+c_1 L)^2 β_x. Here L is the charged particle LET, and c_0,c_1, and c_2 are functions of microscopic parameters and can be served as fitting parameters to the cell‐survival data. In the low LET limit c_1, and c_2 are negligible hence the linear model proposed and used by Wilkins‐Oelfke for the proton treatment planning system can be retrieved. The present model fits well the recent clonogenic survival data measured recently in our group in MDACC.

Conclusion:

The present hybrid method provides higher accuracy in calculating the RBE‐weighted dose in the target and normal tissues.