bluuebunny/crossref_metadata_2025_split huggingface dataset:
TH‐CD‐207B‐09: Task‐Driven Fluence Field Modulation Design for Model‐Based Iterative Reconstruction in CT
Authors: Gang G , Siewerdsen J , Stayman J 
Published: July 2016

Purpose:There has been increasing interest in integrating fluence field modulation (FFM) devices with diagnostic CT scanners for dose reduction purposes. Conventional FFM strategies, however, are often either based on heuristics or the analysis of filtered‐backprojection (FBP) performance. This work investigates a prospective task‐driven optimization of FFM for model‐based iterative reconstruction (MBIR) in order to improve imaging performance at the same total dose as conventional strategies.Methods:The task‐driven optimization framework utilizes an ultra‐low dose 3D scout as a patient‐specific anatomical model and a mathematical formation of the imaging task. The MBIR method investigated is quadratically penalized‐likelihood reconstruction. The FFM objective function uses detectability index, d’, computed as a function of the predicted spatial resolution and noise in the image. To optimize performance throughout the object, a maxi‐min objective was adopted where the minimum d’ over multiple locations is maximized. To reduce the dimensionality of the problem, FFM is parameterized as a linear combination of 2D Gaussian basis functions over horizontal detector pixels and projection angles. The coefficients of these bases are found using the covariance matrix adaptation evolution strategy (CMA‐ES) algorithm. The task‐driven design was compared with three other strategies proposed for FBP reconstruction for a calcification cluster discrimination task in an abdomen phantom.Results:The task‐driven optimization yielded FFM that was significantly different from those designed for FBP. Comparing all four strategies, the task‐based design achieved the highest minimum d’ with an 8–48% improvement, consistent with the maxi‐min objective. In addition, d’ was improved to a greater extent over a larger area within the entire phantom.Conclusion:Results from this investigation suggests the need to re‐evaluate conventional FFM strategies for MBIR. The task‐based optimization framework provides a promising approach that maximizes imaging performance under the same total dose constraint.
TH‐D‐BRB‐01: Scripting Fundamentals: Killing Cancer with Code
Authors: Popple R. 
Published: July 2016

Scripting capabilities and application programming interfaces (APIs) are becoming commonly available in modern treatment planning systems. These links to the treatment planning system (TPS) allow users to read data from the TPS, and in some cases use TPS functionality and write data back to the TPS. Such tools are powerful extensions, allowing automation of routine clinical tasks and supporting research, particularly research involving repetitive tasks on large patient populations. The data and functionality exposed by scripting/API capabilities is vendor dependent, as are the languages used by script/API engines, such as the Microsoft .NET framework or Python. Scripts deployed in a clinical environment must be commissioned and validated like any other software tool. This session will provide an overview of scripting applications and a discussion of best practices, followed by a practical introduction to the scripting capabilities of three commercial treatment planning systems.

Learning Objectives:
Understand the scripting capabilities available in several treatment planning systems
Learn how to get started using scripting capabilities
Understand the best practices for safe script deployment in a clinical environmentR. Popple, Varian Medical Systems has provided research support unrelated to the topic of this session.R. Cardan, Varian Medical Systems for grant research, product evaluation, and teaching honorarium.
TH‐D‐BRB‐02: Eclipse Scripting Fundamentals in .NET
Authors: Cardan R. 
Published: July 2016

Scripting capabilities and application programming interfaces (APIs) are becoming commonly available in modern treatment planning systems. These links to the treatment planning system (TPS) allow users to read data from the TPS, and in some cases use TPS functionality and write data back to the TPS. Such tools are powerful extensions, allowing automation of routine clinical tasks and supporting research, particularly research involving repetitive tasks on large patient populations. The data and functionality exposed by scripting/API capabilities is vendor dependent, as are the languages used by script/API engines, such as the Microsoft .NET framework or Python. Scripts deployed in a clinical environment must be commissioned and validated like any other software tool. This session will provide an overview of scripting applications and a discussion of best practices, followed by a practical introduction to the scripting capabilities of three commercial treatment planning systems.

Learning Objectives:
Understand the scripting capabilities available in several treatment planning systems
Learn how to get started using scripting capabilities
Understand the best practices for safe script deployment in a clinical environmentR. Popple, Varian Medical Systems has provided research support unrelated to the topic of this session.R. Cardan, Varian Medical Systems for grant research, product evaluation, and teaching honorarium.
TH‐E‐201‐00: Teaching Radiology Residents: What, How, and Expectation
Authors: Zhang Jie 
Published: July 2016

The ABR Core Examination stresses integrating physics into real‐world clinical practice and, accordingly, has shifted its focus from passive recall of facts to active application of physics principles. Physics education of radiology residents poses a challenge. The traditional method of didactic lectures alone is insufficient, yet it is difficult to incorporate physics teaching consistently into clinical rotations due to time constraints.Faced with this challenge, diagnostic medical physicists who teach radiology residents, have been thinking about how to adapt their teaching to the new paradigm, what to teach and meet expectation of the radiology resident and the radiology residency program. The proposed lecture attempts to discuss above questions. Newly developed diagnostic radiology residents physics curriculum by the AAPM Imaging Physics Curricula Subcommittee will be reviewed. Initial experience on hands‐on physics teaching will be discussed. Radiology resident who will have taken the BAR Core Examination will share the expectation of physics teaching from a resident perspective.The lecture will help develop robust educational approaches to prepare radiology residents for safer and more effective lifelong practice.

Learning Objectives:
Learn updated physics requirements for radiology residents
Pursue effective approaches to teach physics to radiology residents
Learn expectation of physics teaching from resident perspectiveJ. Zhang, This topic is partially supported by RSNA Education Scholar Grant
TH‐EF‐BRA‐04: Individually Optimized Contrast‐Enhanced 4D‐CT for Radiotherapy Simulation in Pancreatic Ductal Adenocarcinoma
Authors: Choi W , Xue M , Lane B , Kang M , Patel K , Regine W , Klahr P , Wang J , Chen S , D'souza W , Lu W 
Published: July 2016

Purpose:To develop an individually optimized contrast‐enhanced (CE) 4D‐CT for radiotherapy simulation in pancreatic ductal adenocarcinomas (PDA).Methods:Ten PDA patients were enrolled. Each underwent 3 CT scans: a 4D‐CT immediately following a CE 3D‐CT and an individually optimized CE 4D‐CT using test injection. Three physicians contoured the tumor and pancreatic tissues. We compared image quality scores, tumor volume, motion, tumor‐to‐pancreas contrast, and contrast‐to‐noise ratio (CNR) in the 3 CTs. We also evaluated interobserver variations in contouring the tumor using simultaneous truth and performance level estimation (STAPLE).Results:Average image quality scores for CE 3DCT and CE 4D‐CT were comparable (4.0 and 3.8, respectively; P=0.47), and both were significantly better than that for 4D‐CT (2.6, P<0.001). Tumor‐to‐pancreas contrast results were comparable in CE 3D‐CT and CE 4D‐CT (15.5 and 16.7 HU, respectively; P=0.71), and the latter was significantly higher than in 4D‐CT (9.2 HU, P=0.03). Image noise in CE 3D‐CT (12.5 HU) was significantly lower than in CE 4D‐CT (22.1 HU, P<0.001) and 4D‐CT (19.4 HU, P=0.005). CNRs were comparable in CE 3D‐CT and CE 4DCT (1.4 and 0.8, respectively; P=0.23), and the former was significantly better than in 4D‐CT (0.6, P = 0.04). Mean tumor volumes were smaller in CE 3D‐CT (29.8 cm3) and CE 4D‐CT (22.8 cm3) than in 4D‐CT (42.0 cm3), although these differences were not statistically significant. Mean tumor motion was comparable in 4D‐CT and CE 4D‐CT (7.2 and 6.2 mm, P=0.23). Interobserver variations were comparable in CE 3D‐CT and CE 4D‐CT (Jaccard index 66.0% and 61.9%, respectively) and were worse for 4D‐CT (55.6%) than CE 3D‐CT.Conclusion:CE 4D‐CT demonstrated characteristics comparable to CE 3D‐CT, with high potential for simultaneously delineating the tumor and quantifying tumor motion with a single scan.Supported in part by Philips Healthcare.
TH‐EF‐BRA‐07: Evaluation of Internal Target Volume Derived From a Prototype 4D‐MRI Sequence with 3D Radial Stack‐Of‐Stars Trajectory and K‐Space Self‐Gating
Authors: Yang W , Fan Z , Deng Z , Pang J , Bi X , Fenchel M , Li D , Fraass B , Hakimian B , Reznik R , Bryant M , Sandler H , Tuli R 
Published: July 2016

Purpose:4D‐MRI based on resorting of 2D‐cine‐MRI images shows great potential to assess tumor motion more accurately compared to 4D‐CT, however, it suffers from low through‐plane resolution and stitching artifacts. 4D‐MRI based on 3D acquisition results in stitching‐artifact‐free images with high in‐plane and through‐plane resolutions. In this study, we report our early clinical experience of a prototype 4D‐MRI sequence with 3D stack‐of‐stars (SOS) trajectory for internal target volume (ITV) definition.Methods:Ten patients with 13 total lesions (7 pancreatic, 1 lung with 2 lesions, 1 liver with 3 lesions and 1 esophagus) were recruited. 4D‐MRI used in‐plane radial and through‐plane Cartesian sampling. Two imaging orientations, i.e. axial slab (A) and coronal slab (B), were compared. ITVs were derived from 3‐bin (ITV3), 5‐bin (ITV5) and 10‐bin (ITV10) reconstruction protocols. ITV5 was set as standard and minimum expansion of ITV3 needed to encompass ITV5 was derived. Similarity index was calculated from ITV3 and ITV5 (SI3/5), and ITV10 and ITV5 (SI10/5). Imaging noise was calculated for both method A and B. Wilcoxon‐rank‐sum test was performed with a p value <0.05 deemed as significant.Results:No significant difference (p=0.34) was observed from method A and B, indicating a uniform imaging noise distribution from 3D acquisition. Imaging noise and artifacts were visually different from different binning protocols, with more bins resulting in more noise, more artifacts and larger ITV. On average, ITV differs by 7% (1%–19%) comparing ITV3 with ITV5 for the patient cohort. For the pancreas sub‐group, ITV differs by 4% (1%–6%). An average of 2.3mm (2mm‐3mm) expansion was needed for ITV3 to encompass ITV5. SI10/5 was 0.93±0.03 (mean±σ) and SI3/5 was 0.95±0.03.Conclusion:4D‐MRI with 3D SOS trajectory was evaluated on 10 patients. Significant difference in ITV was observed with different binning protocols. Imaging noise was similar irrespective of the imaging orientations.This work is partially supported by NIH R03CA173273 and CTSI core voucher award.
TH‐E‐202‐02: The Use of Hypoxia PET Imaging for Radiotherapy
Authors: Humm J. 
Published: July 2016

PET/CT is a very important imaging tool in the management of oncology patients. PET/CT has been applied for treatment planning and response evaluation in radiation therapy. This educational session will discuss:

Pitfalls and remedies in PET/CT imaging for RT planning
The use of hypoxia PET imaging for radiotherapy
PET for tumor response evaluationThe first presentation will address the issue of mis‐registration between the CT and PET images in the thorax and the abdomen. We will discuss the challenges of respiratory gating and introduce an average CT technique to improve the registration for dose calculation and image‐guidance in radiation therapy. The second presentation will discuss the use of hypoxia PET Imaging for radiation therapy. We will discuss various hypoxia radiotracers, the choice of clinical acquisition protocol (in particular a single late static acquisition versus a dynamic acquisition), and the compartmental modeling with different transfer rate constants explained. We will demonstrate applications of hypoxia imaging for dose escalation/de‐escalation in clinical trials. The last presentation will discuss the use of PET/CT for tumor response evaluation. We will discuss anatomic response assessment vs. metabolic response assessment, visual evaluation and semi‐quantitative evaluation, and limitations of current PET/CT assessment. We will summarize clinical trials using PET response in guiding adaptive radiotherapy. Finally, we will summarize recent advancements in PET/CT radiomics and non‐FDG PET tracers for response assessment.

Learning Objectives:
Identify the causes of mis‐registration of CT and PET images in PET/CT, and review the strategies to remedy the issue.
Understand the basics of PET imaging of tumor hypoxia (radiotracers, how PET measures the hypoxia selective uptake, imaging protocols, applications in chemo‐radiation therapy).
Understand the basics of dynamic PET imaging, compartmental modeling and parametric images.
Understand the basics of using FDG PET/CT for tumor response evaluation.
Learn about recent advancement in PET/CT radiomics and non‐FDG PET tracers for response assessment.This work was supported in part by the National Cancer Institute Grants R01CA172638.; W. Lu, This work was supported in part by the National Cancer Institute Grants R01CA172638.
TH‐EF‐207A‐05: Feasibility of Applying SMEIR Method On Small Animal 4D Cone Beam CT Imaging
Authors: Zhong Y , Zhang Y , Shao Y , Wang J 
Published: July 2016

Purpose:Small animal cone beam CT imaging has been widely used in preclinical research. Due to the higher respiratory rate and heat beats of small animals, motion blurring is inevitable and needs to be corrected in the reconstruction. Simultaneous motion estimation and image reconstruction (SMEIR) method, which uses projection images of all phases, proved to be effective in motion model estimation and able to reconstruct motion‐compensated images. We demonstrate the application of SMEIR for small animal 4D cone beam CT imaging by computer simulations on a digital rat model.Methods:The small animal CBCT imaging system was simulated with the source‐to‐detector distance of 300 mm and the source‐to‐object distance of 200 mm. A sequence of rat phantom were generated with 0.4 mm3 voxel size. The respiratory cycle was taken as 1.0 second and the motions were simulated with a diaphragm motion of 2.4mm and an anterior‐posterior expansion of 1.6 mm. The projection images were calculated using a ray‐tracing method, and 4D‐CBCT were reconstructed using SMEIR and FDK methods. The SMEIR method iterates over two alternating steps: 1) motion‐compensated iterative image reconstruction by using projections from all respiration phases and 2) motion model estimation from projections directly through a 2D‐3D deformable registration of the image obtained in the first step to projection images of other phases.Results:The images reconstructed using SMEIR method reproduced the features in the original phantom. Projections from the same phase were also reconstructed using FDK method. Compared with the FDK results, the images from SMEIR method substantially improve the image quality with minimum artifacts.Conclusion:We demonstrate that it is viable to apply SMEIR method to reconstruct small animal 4D‐CBCT images.
TH‐F‐202‐02: Current Applications of MRI in Radiotherapy
Authors: Li G. 
Published: July 2016

MRI has excellent soft tissue contrast and can provide both anatomical and physiological information. It is becoming increasingly important in radiation therapy for treatment planning, image‐guided radiation therapy, and treatment assessment. It is critically important at this time point to educate and update our medical physicists about MRI to prepare for the upcoming surge of MRI applications in radiation therapy. This session will review important basics of MR physics, pulse sequence designs, and current radiotherapy application, as well as showcase exciting new developments in MRI that can be potentially useful in radiation therapy.

Learning Objectives:
To learn basics of MR physics and understand the differences between various pulse sequences
To review current applications of MRI in radiation therapy.To discuss recent MRI advances for future MRI guided radiation therapyPartly supported by NIH (1R21CA165384).; W. Miller, Research supported in part by Siemens Healthcare; G. Li, My clinical research is in part supported by NIH U54CA137788. I have a collaborative research project with Philips Healthcare.; J. Cai, jing cai
Water slide injuries in Jamaica
Authors: Fletcher Cary K , McDowell Derrick 
Published: July 2016

BackgroundPatients are presented in this study to describe injuries, each of which have not been previously described in the literature, as a result of a specific mechanism of injury on a water slide. Some of these injuries are potentially fatal and are usually the result of a very high energy mechanism of injury. All injuries occurred in a 6-week time span in the summer of 2015.MethodInjuries arising from water slides and their definitive treatment were documented. All of the cases presented to Saint Ann's Bay Hospital in Saint Ann's Bay, Jamaica. The mechanism of injury was analyzed with a view to implement preventative measures.ResultsThree cases had open book pelvic injuries and one of them also had a vaginal tear. All of the open book injuries occurred after the patron's thighs violently abducted despite adhering to the recommended starting position that suggested patrons cross their legs. The fourth case was of a 25-year-old man who sustained a posterior shoulder dislocation as a result of his arms flailing despite attempting to adhere to the rule recommending that the patron place his arms across his chest. The final case was of a 14-year-old boy who was involved in an atypical collision injury, resulting in the boy sustaining a displaced distal femoral fracture.ConclusionsModern water slides will expose patrons to more frequent and severe injuries from atypical mechanisms of injuries. Risk factors for injury must be factored into preventative measures. Improved surveillance strategies to monitor these injuries are suggested.
Printed Perforated Lampshades for Continuous Projective Images
Authors: Zhao Haisen , Lu Lin , Wei Yuan , Lischinski Dani , Sharf Andrei , Cohen-Or Daniel , Chen Baoquan 
Published: July 2016

We present a technique for designing three-dimensional- (3D) printed perforated lampshades that project continuous grayscale images onto the surrounding walls. Given the geometry of the lampshade and a target grayscale image, our method computes a distribution of tiny holes over the shell, such that the combined footprints of the light emanating through the holes form the target image on a nearby diffuse surface. Our objective is to approximate the continuous tones and the spatial detail of the target image to the extent possible within the constraints of the fabrication process.
To ensure structural integrity, there are lower bounds on the thickness of the shell, the radii of the holes, and the minimal distances between adjacent holes. Thus, the holes are realized as thin tubes distributed over the lampshade surface. The amount of light passing through a single tube may be controlled by the tube’s radius and by its orientation (tilt angle). The core of our technique thus consists of determining a suitable configuration of the tubes: their distribution across the relevant portion of the lampshade, as well as the parameters (radius, tilt angle) of each tube. This is achieved by computing a capacity-constrained Voronoi tessellation over a suitably defined density function and embedding a tube inside the maximal inscribed circle of each tessellation cell.
Understanding Latency Variation in Modern DRAM Chips
Authors: Chang Kevin K. , Kashyap Abhijith , Hassan Hasan , Ghose Saugata , Hsieh Kevin , Lee Donghyuk , Li Tianshi , Pekhimenko Gennady , Khan Samira , Mutlu Onur 
Published: July 2016

Long DRAM latency is a critical performance bottleneck in current systems. DRAM access latency is defined by three fundamental operations that take place within the DRAM cell array: (i) activation of a memory row, which opens the row to perform accesses; (ii) precharge, which prepares the cell array for the next memory access; and (iii) restoration of the row, which restores the values of cells in the row that were destroyed due to activation. There is significant latency variation for each of these operations across the cells of a single DRAM chip due to irregularity in the manufacturing process. As a result, some cells are inherently faster to access, while others are inherently slower. Unfortunately, existing systems do not exploit this variation.
The goal of this work is to (i) experimentally characterize and understand the latency variation across cells within a DRAM chip for these three fundamental DRAM operations, and (ii) develop new mechanisms that exploit our understanding of the latency variation to reliably improve performance. To this end, we comprehensively characterize 240 DRAM chips from three major vendors, and make several new observations about latency variation within DRAM. We find that (i) there is large latency variation across the cells for each of the three operations; (ii) variation characteristics exhibit significant spatial locality: slower cells are clustered in certain regions of a DRAM chip; and (iii) the three fundamental operations exhibit different reliability characteristics when the latency of each operation is reduced.
Based on our observations, we propose Flexible-LatencY DRAM (FLY-DRAM), a mechanism that exploits latency variation across DRAM cells within a DRAM chip to improve system performance. The key idea of FLY-DRAM is to exploit the spatial locality of slower cells within DRAM, and access the faster DRAM regions with reduced latencies for the fundamental operations. Our evaluations show that FLY-DRAM improves the performance of a wide range of applications by 13.3%, 17.6%, and 19.5%, on average, for each of the three different vendors' real DRAM chips, in a simulated 8-core system. We conclude that the experimental characterization and analysis of latency variation within modern DRAM, provided by this work, can lead to new techniques that improve DRAM and system performance.