bluuebunny/crossref_metadata_2025 huggingface dataset:
TU‐EF‐210‐05: A Fast and Efficient Method for Determining Coagulation Temperatures of Tissue‐Mimicking Thermal Therapy Gel Phantoms: Validated by Magnetic Resonance Thermometry
Authors: Brodin P , Partanen A , Asp P , Branch C , Guha C , Tome W
Published: June 2015

Purpose:

To develop a simple and efficient method for determining coagulation temperatures of transparent thermal therapy gel phantoms. Tissue‐mimicking thermal therapy phantoms (TMTTPs) that coagulate at specific temperatures are valuable tools for developing and evaluating treatment strategies related to therapy using focused ultrasound, laser, microwave or radiofrequency ablation. The specific formula for a TMTTP will depend on the application and as such finding the coagulation temperature for a specific TMTTP is crucial.

Methods:

We used a previously published TMTTP formula with 2% (w/v) of bovine serum albumin as the temperature sensitive protein. Using the programmable heating settings of a polymerase chain reaction (PCR) machine we heated 50 µl gel samples to various temperatures for 3 min and imaged them to determine the coagulation temperature by quantifying the resulting opacity. These measured coagulation temperatures were then validated using high‐intensity focused ultrasound (HIFU) heating and magnetic resonance thermometry and T2 mapping using a clinical MR‐HIFU system.

Results:

The PCR heating method produced consistent and reproducible coagulation of the gel samples, and the coagulation temperature was determined by a 7.5% increase in opacity compared to non‐coagulated gel samples. The resulting coagulation temperatures for TMTTPs of increasing pH levels were found to be 43.6 ± 0.4 °C, 53.1 ± 0.8 °C and 60.1 ± 1.0 °C for a pH of 4.25, 4.50 and 4.75, respectively. The corresponding coagulation temperatures determined by MR thermometry were within the range of 50 to 55 °C for pH 4.50 and within 58 to 66 °C for pH 4.75.

Conclusion:

The PCR heating method provides a fast and reproducible measurement of the coagulation temperature of transparent TMTTPs. The temperatures determined using this method were well within the range of coagulation temperatures determined using the MR‐thermometry validation.

Dr. Ari Partanen is a paid employee of Philips Healthcare
TU‐F‐BRB‐01: Resolving and Characterizing Breathing Motion for Radiotherapy with MRI
Authors: Tryggestad E.
Published: June 2015

The current clinical standard of organ respiratory imaging, 4D‐CT, is fundamentally limited by poor soft‐tissue contrast and imaging dose. These limitations are potential barriers to beneficial “4D” radiotherapy methods which optimize the target and OAR dose‐volume considering breathing motion but rely on a robust motion characterization. Conversely, MRI imparts no known radiation risk and has excellent soft‐tissue contrast. MRI‐based motion management is therefore highly desirable and holds great promise to improve radiotherapy of moving cancers, particularly in the abdomen. Over the past decade, MRI techniques have improved significantly, making MR‐based motion management clinically feasible. For example, cine MRI has high temporal resolution up to 10 f/s and has been used to track and/or characterize tumor motion, study correlation between external and internal motions. New MR technologies, such as 4D‐MRI and MRI hybrid treatment machines (i.e. MR‐linac or MR‐Co60), have been recently developed. These technologies can lead to more accurate target volume determination and more precise radiation dose delivery via direct tumor gating or tracking. Despite all these promises, great challenges exist and the achievable clinical benefit of MRI‐based tumor motion management has yet to be fully explored, much less realized. In this proposal, we will review novel MR‐based motion management methods and technologies, the state‐of‐the‐art concerning MRI development and clinical application and the barriers to more widespread adoption.

Learning Objectives:

Discuss the need of MR‐based motion management for improving patient care in radiotherapy.

Understand MR techniques for motion imaging and tumor motion characterization.

Understand the current state of the art and future steps for clinical integration.

Henry Ford Health System holds research agreements with Philips Healthcare. Research sponsored in part by a Henry Ford Health System Internal Mentored Grant.
TU‐G‐213‐00: The International Electrotechnical Commission (IEC): What Is It and Why Should Medical Physicists Care?
Authors: Supanich Mark
Published: June 2015

The International Electrotechnical Commission (IEC) writes standards that manufacturers of electrical equipment must comply with. Medical electrical equipment, such as medical imaging, radiation therapy, and radiation dosimetry devices, fall under Technical Committee 62. Of particular interest to medical physicists are the standards developed within Subcommittees (SC) 62B, which addresses diagnostic radiological imaging equipment, and 62C, which addresses equipment for radiation therapy, nuclear medicine and dosimetry. For example, a Working Group of SC 62B is responsible for safety and quality assurance standards for CT scanners and a Working Group of SC 62C is responsible for standards that set requirements for dosimetric safety and accuracy of linacs and proton accelerators. IEC standards thus have an impact on every aspect of a medical physicist's job, including equipment testing, shielding design, room layout, and workflow. Consequently, it is imperative that US medical physicists know about existing standards, as well as have input on those under development or undergoing revision.

The structure of the IEC and current standards development work will be described in detail. The presentation will explain how US medical physicists can learn about IEC standards and contribute to their development.

Learning Objectives:

Learn about the structure of the IEC and the influence that IEC standards have on the design of equipment for radiology and radiation therapy.

Learn about the mechanisms by which the US participates in the development and revision of standards.

Understand the specific requirements of several standards having direct relevance to diagnostic and radiation therapy physicists.
TU‐G‐213‐01: IEC and US Committee Activities and Organizational Structure
Authors: Ibbott G.
Published: June 2015

The International Electrotechnical Commission (IEC) writes standards that manufacturers of electrical equipment must comply with. Medical electrical equipment, such as medical imaging, radiation therapy, and radiation dosimetry devices, fall under Technical Committee 62. Of particular interest to medical physicists are the standards developed within Subcommittees (SC) 62B, which addresses diagnostic radiological imaging equipment, and 62C, which addresses equipment for radiation therapy, nuclear medicine and dosimetry. For example, a Working Group of SC 62B is responsible for safety and quality assurance standards for CT scanners and a Working Group of SC 62C is responsible for standards that set requirements for dosimetric safety and accuracy of linacs and proton accelerators. IEC standards thus have an impact on every aspect of a medical physicist's job, including equipment testing, shielding design, room layout, and workflow. Consequently, it is imperative that US medical physicists know about existing standards, as well as have input on those under development or undergoing revision.

The structure of the IEC and current standards development work will be described in detail. The presentation will explain how US medical physicists can learn about IEC standards and contribute to their development.

Learning Objectives:

Learn about the structure of the IEC and the influence that IEC standards have on the design of equipment for radiology and radiation therapy.

Learn about the mechanisms by which the US participates in the development and revision of standards.

Understand the specific requirements of several standards having direct relevance to diagnostic and radiation therapy physicists.
TU‐G‐BRD‐01: Quantifying the Effectiveness of the Physics Pre‐Treatment Plan Review for Detecting Errors in Radiation Therapy
Authors: Gopan O , Novak A , Zeng J , Ford E
Published: June 2015

Purpose:

Physics pre‐treatment plan review is crucial to safe radiation oncology treatments. Studies show that most errors originate in treatment planning, which underscores the importance of physics plan review. As a QA measure the physics review is of fundamental importance and is central to the profession of medical physics. However, little is known about its effectiveness. More hard data are needed. The purpose of this study was to quantify the effectiveness of physics review with the goal of improving it.

Methods:

This study analyzed 315 “potentially serious” near‐miss incidents within an institutional incident learning system collected over a two‐year period. 139 of these originated prior to physics review and were found at the review or after. Incidents were classified as events that: 1)were detected by physics review, 2)could have been detected (but were not), and 3)could not have been detected. Category 1 and 2 events were classified by which specific check (within physics review) detected or could have detected the event.

Results:

Of the 139 analyzed events, 73/139 (53%) were detected or could have been detected by the physics review; although, 42/73 (58%) were not actually detected. 45/73 (62%) errors originated in treatment planning, making physics review the first step in the workflow that could detect the error. Two specific physics checks were particularly effective (combined effectiveness of >20%): verifying DRRs (8/73) and verifying isocenter (7/73). Software‐based plan checking systems were evaluated and found to have potential effectiveness of 40%. Given current data structures, software implementations of some tests such as isocenter verification check would be challenging.

Conclusion:

Physics plan review is a key safety measure and can detect majority of reported events. However, a majority of events that potentially could have been detected were NOT detected in this study, indicating the need to improve the performance of physics review.
TU‐G‐BRA‐05: Predicting Volume Change of the Tumor and Critical Structures Throughout Radiation Therapy by CT‐CBCT Registration with Local Intensity Correction
Authors: Park S , Robinson A , Plishker W , Shekhar R , Kiess A , Quon H , Wong J , Lee J
Published: June 2015

Purpose:

The purpose of this study is to develop an accurate and effective technique to predict and monitor volume changes of the tumor and organs at risk (OARs) from daily cone‐beam CTs (CBCTs).

Methods:

While CBCT is typically used to minimize the patient setup error, its poor image quality impedes accurate monitoring of daily anatomical changes in radiotherapy. Reconstruction artifacts in CBCT often cause undesirable errors in registration‐based contour propagation from the planning CT, a conventional way to estimate anatomical changes. To improve the registration and segmentation accuracy, we developed a new deformable image registration (DIR) that iteratively corrects CBCT intensities using slice‐based histogram matching during the registration process. Three popular DIR algorithms (hierarchical B‐spline, demons, optical flow) augmented by the intensity correction were implemented on a graphics processing unit for efficient computation, and their performances were evaluated on six head and neck (HN) cancer cases. Four trained scientists manually contoured nodal gross tumor volume (GTV) on the planning CT and every other fraction CBCTs for each case, to which the propagated GTV contours by DIR were compared. The performance was also compared with commercial software, VelocityAI (Varian Medical Systems Inc.).

Results:

Manual contouring showed significant variations, [‐76, +141]% from the mean of all four sets of contours. The volume differences (mean±std in cc) between the average manual segmentation and four automatic segmentations are 3.70±2.30(B‐spline), 1.25±1.78(demons), 0.93±1.14(optical flow), and 4.39±3.86 (VelocityAI). In comparison to the average volume of the manual segmentations, the proposed approach significantly reduced the estimation error by 9%(B‐spline), 38%(demons), and 51%(optical flow) over the conventional mutual information based method (VelocityAI).

Conclusion:

The proposed CT‐CBCT registration with local CBCT intensity correction can accurately predict the tumor volume change with reduced errors. Although demonstrated only on HN nodal GTVs, the results imply improved accuracy for other critical structures.

This work was supported by NIH/NCI under grant R42CA137886.
TU‐G‐BRA‐07: Characterization of Tumor Proliferation During Successive Cycles of Anti‐Angiogenic Therapy Using [F‐18]FLT PET/CT
Authors: Scarpelli M , Perlman S , Harmon S , Perk T , Scully P , Bruce J , Liu G , Jeraj R
Published: June 2015

Purpose:

Studies have shown cessation of anti‐angiogenic treatment during the first cycle of therapy resulted in rebound of tumor proliferation (flare). This study characterized proliferation dynamics during the first and third cycle of anti‐angiogenic treatment using [F‐18]FLT PET.

Methods:

Thirteen patients with various solid cancers were treated with Axitinib (Pfizer, Inc) at a dose of 5mg orally, twice daily, on contiguous three‐week cycles with intermittent dosing (two‐weeks‐on/one‐week‐off). All patients received three FLT PET/CT scans during cycle 1 (C1): at baseline (C1D0), peak Axitinib concentration (C1D14), and the end of washout (C1D21). Ten patients received up to an additional three scans at corresponding time points during cycle 3 (C3). Lesions were identified by a nuclear medicine physician and manually contoured. Tumor burden was quantified using standard SUV metrics. Correlations between imaging metrics across C1 and C3 were calculated using the Spearman correlation.

Results:

At C1 peak drug concentration 11/13 patients had decreases in SUVtotal, with median decrease of 50% (change from C1D0 to C1D14). At C3 peak drug concentration 7/7 patients had decreases in SUVtotal, with median decrease of 20% (C3D0 to C3D14). Proliferative flare during C1 washout (>20% increase from C1D14 to C1D21) occurred in 9/13 patients, with median SUVtotal increase of 190%. Flare was also seen in C3 for 5/5 patients, with median SUVtotal increase of 70% (change from C3D14 to C3D21). Correlations were found between changes in imaging metrics across C1 and C3, notably the change in SUVtotal from C1D0 to C1D21 and the change in SUVtotal from C1D0 to C3D0 (ρ = 0.80).

Conclusion:

Measurements of SUVtotal showed that both patient response to treatment and flare were evident in both cycles of treatment. Correlation between changes in SUVtotal across C1 and C3 suggest early time points could be used to characterize patient response in later cycles.

Research funded in part by Pfizer.
TU‐G‐BRA‐08: BEST IN PHYSICS (JOINT IMAGING‐THERAPY): Hybrid PET‐MRI Imaging of Acute Radiation Induced Cardiac Toxicity
Authors: El‐Sherif O , Xhaferllari I , Sykes J , Butler J , Wisenberg G , Prato F , Gaede S
Published: June 2015

Purpose:

To identify the presence of low‐dose radiation induced cardiac toxicity in a canine model using hybrid positron emission tomography (PET) and magnetic resonance imaging (MRI).

Methods:

Research ethics board approval was obtained for a longitudinal imaging study of 5 canines after cardiac irradiation. Animals were imaged at baseline, 1 week post cardiac irradiation, and 1 month post cardiac irradiation using a hybrid PET‐ MRI system (Biograph mMR, Siemens Healthcare). The imaging protocol was designed to assess acute changes in myocardial perfusion and inflammation. Myocardial perfusion imaging was performed using N13‐ammonia tracer followed by a dynamic PET acquisition scan. A compartmental tracer kinetic model was used for absolute perfusion quantification. Myocardial inflammation imaging was performed using F18‐fluorodeoxyglucose (FDG) tracer. The standard uptake value (SUV) over a region encompassing the whole heart was used to compare FDG scans. All animals received a simulation CT scan (GE Medical Systems) for radiation treatment planning. Radiation treatment plans were created using the Pinncale3 treatment planning system (Philips Radiation Oncology Systems) and designed to resemble the typical cardiac exposure during left‐sided breast cancer radiotherapy. Cardiac irradiations were performed in a single fraction using a TrueBeam linear accelerator (Varian Medical Systems).

Results:

The delivered dose (mean ± standard deviation) to heart was 1.8±0.2 Gy. Reductions in myocardial stress perfusion relative to baseline were observed in 2 of the 5 animals 1 month post radiation. A global inflammatory response 1 month post radiation was observed in 4 of the 5 animals. The calculated SUV at 1 month post radiation was significantly higher (p=0.05) than the baseline SUV.

Conclusion:

Low doses of cardiac irradiation (< 2 Gy) may lead to myocardial perfusion defects and a global inflammatory response that can be detectable as early as 1 month post irradiation using hybrid PET‐MRI imaging techniques.
TU‐G‐201‐00: Imaging Equipment Specification and Selection in Radiation Oncology Departments
Authors: Hua Chia‐Ho
Published: June 2015

This session will update therapeutic physicists on technological advancements and radiation oncology features of commercial CT, MRI, and PET/CT imaging systems. Also described are physicists’ roles in every stage of equipment selection, purchasing, and operation, including defining specifications, evaluating vendors, making recommendations, and optimal and safe use of imaging equipment in radiation oncology environment.

The first presentation defines important terminology of CT and PET/CT followed by a review of latest innovations, such as metal artifact reduction, statistical iterative reconstruction, radiation dose management, tissue classification by dual energy CT and spectral CT, improvement in spatial resolution and sensitivity in PET, and potentials of PET/MR. We will also discuss important technical specifications and items in CT and PET/CT purchasing quotes and their impacts.

The second presentation will focus on key components in the request for proposal for a MRI simulator and how to evaluate vendor proposals. MRI safety issues in radiation Oncology, including MRI scanner Zones (4‐zone design), will be discussed. Basic MR terminologies, important functionalities, and advanced features, which are relevant to radiation therapy, will be discussed.

In the third presentation, justification of imaging systems for radiation oncology, considerations in room design and construction in a RO department, shared use with diagnostic radiology, staffing needs and training, clinical/research use cases and implementation, will be discussed. The emphasis will be on understanding and bridging the differences between diagnostic and radiation oncology installations, building consensus amongst stakeholders for purchase and use, and integrating imaging technologies into the radiation oncology environment.

Learning Objectives:

Learn the latest innovations of major imaging systems relevant to radiation therapy

Be able to describe important technical specifications of CT, MRI, and PET/CT

Understand the process of budget request, equipment justification, comparisons of technical specifications, site visits, vendor selection, and contract development
TU‐G‐210‐03: Acoustic Simulations in Transcranial MRgFUS: Treatment Prediction and Analysis
Authors: Vyas U.
Published: June 2015

Modeling can play a vital role in predicting, optimizing and analyzing the results of therapeutic ultrasound treatments. Simulating the propagating acoustic beam in various targeted regions of the body allows for the prediction of the resulting power deposition and temperature profiles. In this session we will apply various modeling approaches to breast, abdominal organ and brain treatments. Of particular interest is the effectiveness of procedures for correcting for phase aberrations caused by intervening irregular tissues, such as the skull in transcranial applications or inhomogeneous breast tissues. Also described are methods to compensate for motion in targeted abdominal organs such as the liver or kidney.

Douglas Christensen – Modeling for Breast and Brain HIFU Treatment Planning

Tobias Preusser – TRANS‐FUSIMO ‐ An Integrative Approach to Model‐Based Treatment Planning of Liver FUS

Urvi Vyas – Acoustic Simulations in Transcranial MRgFUS: Treatment Prediction and Analysis

Learning Objectives:

Understand the role of acoustic beam modeling for predicting the effectiveness of therapeutic ultrasound treatments.

Apply acoustic modeling to specific breast, liver, kidney and transcranial anatomies.

Determine how to obtain appropriate acoustic modeling parameters from clinical images.

Understand the separate role of absorption and scattering in energy delivery to tissues.

See how organ motion can be compensated for in ultrasound therapies.

Compare simulated data with clinical temperature measurements in transcranial applications.

Supported by NIH R01 HL172787 and R01 EB013433 (DC); EU Seventh Framework Programme (FP7/2007‐2013) under 270186 (FUSIMO) and 611889 (TRANS‐FUSIMO)(TP); and P01 CA159992, GE, FUSF and InSightec (UV).
TU‐F‐CAMPUS‐J‐01: Inference of Prostate PTV Margins in VMAT Delivery From Intra‐Fraction Prostate Motion During SBRT Delivery
Authors: Thind K , Wong R , Wong D , Gerdes C , Chow T
Published: June 2015

Purpose:

To retrospectively quantify the intra‐fraction prostate motion during stereotactic body radiation therapy (SBRT) treatment using CyberKnife's target tracking system, which may provide insight into expansion margins from GTV to PTV used in gantry‐based treatments. CyberKnife is equipped with an active tracking system (InTempo) that tracks the four fiducials placed in the prostate gland. The system acquires intra‐fraction orthogonal kV images at 45° and 315° in a sequential fashion.

Methods:

A total of 38 patients treated with SBRT using CyberKnife between 2011 and 2013 were studied. Dose‐regime was 36.25 Gy in 5 fractions (7.25 Gy/fraction, twice per week) as per RTOG 0938 guidelines. The CyberKnife image tracking logs for all SBRT treatments using InTempo were examined. A total of 13663 images were examined for the superior/inferior (SI), anterior/posterior (AP) and left/right (LR) translation as well as roll, pitch and yaw rotations for the target position relative to the last known model position.

Results:

The mean ± 2 SD of intra‐fraction motion was contained within 3 mm for SI and LR and 4.5 mm for AP directions at 5 minutes into the treatment delivery. It was contained within 4 mm for SI and LR and 5 mm for AP at 10 minutes. At 15 minutes into delivery, all translations were contained within 5 mm. The mean ± 2 SD of prostate roll, pitch and yaw increased with time but were contained within 5 degree at 5, 10 and 15 minutes into treatment. Additionally, target translations and rotations were within ± 1 mm and ± 1 degree for 90% and 78% of the time.

Conclusion:

The organ motion component of PTV margin for 10 minute VMAT delivery is contained within 4 mm in SI and LR direction and within 5 mm in the AP direction.
TU‐F‐CAMPUS‐J‐02: Mooney‐Rivlin Biomechanical Modeling of Lung with Inhomogeneous Material Property
Authors: Tehrani J Nasehi , Guo X , Wang J
Published: June 2015

Purpose:

The Mooney‐Rivlin material with hyperelastic strain energy has been proposed for realistic biomechanical modeling of lung. In this study, the lung is modeled as an inhomogeneous Mooney‐Rivlin material with the incompressibility factors being optimized to improve the tumor center of mass (TCM) motion simulation accuracy during respiration.

Method:

ITK‐SNAP was used to segment lungs of eight lung cancer patients from the 4D‐CT images and tetrahedral volume meshes of the lungs in phase 50% were created by using adaptive mesh generation toolkit. The interphase deformation vector fields (DVFs) are calculated by demons deformable registration algorithm and the barycentric coordinate system of tetrahedral elements is obtained from the resulted DVFs. Mooney‐Rivlin hyperelastic material is used to model the lung volume. Each element is considered unique where the incompressibility factor (k‐factor) for each element is assumed to be proportional to the magnitude of normalized DVF. The incompressibility factor for each element was optimized by minimizing the tumor center of mass motion simulation error.

Results:

If lung is considered as a homogenous material in Mooney‐Rivlin modeling, the average TCM motion simulation error is 2.26 mm. By considering inhomogeneous properties of lung in the proposed strategy, the average TCM motion simulation error is reduced to 2.04 mm.

Conclusions:

We proposed a method for assigning the inhomogeneous biomechanical material in the Mooney‐Rivlin model of lung based on the lung regional deformation vector fields. Inhomogeneous material property of lung improves the simulation accuracy.
WE‐E‐BRB‐02: Knowledge Modeling For Clinical Treatment Planning
Authors: Wu Q.
Published: June 2015

The knowledge‐based treatment planning automation has evolved from academic research from the clinical application with the involvement of the major industry TPS vendors. Previous work proved the concept that IMRT or VMAT plans can be designed without or with minimal human intervention. Recently, the major industry vendors start releasing the automatic planning product such as Philips automatic treatment planning, Varian's Rapidplan, and RaySearch's autoplan. Many centers start to evaluate and use the automatic planning products from TPS vendors. It is more and more becoming evident that automatic planning will be routinely used in the clinic.

The first presentation will focus on the knowledge modeling for clinical treatment planning. The presenter will introduce the algorithm and theory for developing the dose volume histogram (DVH) model, summarize the results on the validation of the DVH model, and discuss the application of DVH for the automatic treatment planning. The second presenter will focus on the clinical use of the automatic treatment planning. The presenter will give an overview of the several automatic treatment planning tools including the tools developed commercially and in‐house, present the early experience of using those tools, and discuss the application of the tools in the routine clinical use and in the quality control of the treatment planning.

Learning Objectives:

Describe the algorithm and theory behind the knowledge based treatment planning automation.

Clinical experience of using automatic planning in clinical trial and patient treatment

Early clinical experience of using commercial automatic planning approach

The application of automatic planning approach to perform quality assurance of treatment plan.

XD obtain the research funding from Varian Medical System, Philips Medical System and Funding support form Sister Institution Network Fund of MD Anderson, XD is also a founder of Global Oncology One
WE‐EF‐BRA‐01: A Dual‐Use Optical Tomography System for Small Animal Radiation Research Platform (SARRP)
Authors: Wang K , Bin Z , He X , Iordachita I , Wong J
Published: June 2015

Purpose:

We develop a novel dual‐use configuration for a tri‐modality, CBCT/bioluminescence tomography(BLT)/fluorescence tomography(FT), imaging system with the SARRP that can function as a standalone system for longitudinal imaging research and on‐board the SARRP to guide irradiation. BLT provides radiation guidance for soft tissue target, while FT offers functional information allowing mechanistic investigations.

Methods:

The optical assembly includes CCD camera, lens, filter wheel, 3‐way mirrors, scanning fiber system and light‐tight enclosure. The rotating mirror system directs the optical signal from the animal surface to the camera at multiple projection over 180 degree. The fiber‐laser system serves as the external light source for the FT application. Multiple filters are used for multispectral imaging to enhance localization accuracy using BLT. SARRP CBCT provides anatomical information and geometric mesh for BLT/FT reconstruction. To facilitate dual use, the 3‐way mirror system is cantilevered in front of the camera. The entire optical assembly is driven by a 1D linear stage to dock onto an independent mouse support bed for standalone application. After completion of on‐board optical imaging, the system is retracted from the SARRP to allow irradiation of the mouse.

Results:

A tissue‐simulating phantom and a mouse model with a luminescence light source are used to demonstrate the function of the dual‐use optical system. Feasibility data have been obtained based on a manual‐docking prototype. The center of mass of light source determined in living mouse with on‐board BLT is within 1±0.2mm of that with CBCT. The performance of the motorized system is expected to be the same and will be presented.

Conclusion:

We anticipate the motorized dual use system provide significant efficiency gain over our manual docking and off‐line system. By also supporting off‐line longitudinal studies independent of the SARRP, the dual‐use system is a highly efficient and cost‐effective platform to facilitate optical imaging for pre‐clinical radiation research.

The work is supported by NIH R01CA158100 and Xstrahl Ltd. Drs. John Wong and Iulian Iordachita receive royalty payment from a licensing agreement between Xstrahl Ltd and Johns Hopkins University. John Wong also has a consultant agreement with Xstrahl Ltd.
WE‐EF‐BRA‐03: Catheter‐ Free Ablation with External Photon Radiation: Treatment Planning, Delivery Considerations, and Correlation of Effects with Delivered Dose
Authors: Deisher A , Anderson S , Cusma J , Herman M , Johnson S , Lehmann H , Packer D , Parker K , Song L , Takami M , Kruse J
Published: June 2015

Purpose:

To plan, target, and calculate delivered dose in atrioventricular node (AVN) ablation with volume‐modulated arc therapy (VMAT) in an intact porcine model.

Methods:

Seven pigs underwent AVN irradiation, with prescription doses ranging between 25 and 55Gy in a single fraction. Cardiac CT scans were acquired at expiration. Two physicians contoured AVN targets on 10 phases, providing estimates of target motion and inter‐physician variability. Treatment planning was conducted on a static phase‐averaged CT. The volume designated to receive prescription dose covered the full extent of AVN cardiac motion, expanded by 4mm for setup uncertainty. Optimization limited doses to risk structures according to single‐fraction tumor treatment protocols. Orthogonal kV images were used to align bony anatomy at time of treatment. Localization was further refined with respiratory‐gated cone‐beam CT, and range of cardiac motion was verified under fluoroscopy. Beam delivery was respiratory‐gated for expiration with a mean efficiency of 60%. Deformable registration of the 10 cardiac CT phases was used to calculate actual delivered dose for comparison to electro‐anatomical and visually evident lesions.

Results:

The mean [minimum,maximum] amplitude of AVN cardiac motion was LR 2.9 [1.7,3.9]mm, AP 6.6 [4.4,10.4]mm, and SI 5.6 [2.0,9.9]mm. Incorporating cardiac motion into the dose calculation showed the volume receiving full dose was 40–80% of the volume indicated on the static planning image, although the contoured AVN target received full dose in all animals. Initial results suggest the dimensions of the electro‐anatomical lesion are correlated with the 40Gy isodose volume.

Conclusion:

Image‐guidance techniques allow for accurate and precise delivery of VMAT for catheter‐free arrhythmia ablation. An arsenal of advanced radiation planning, dose optimization, and image‐guided delivery techniques was employed to assess and mitigate effects of cardiac and respiratory motion. Feasibility of delivery to the pulmonary veins and left ventricular myocardium will be investigated in future studies.

D. Packer Disclosures: Abiomed, Biosense Webster, Inc., Boston Scientific Corp., CardioFocus, Inc., Johnson and Johnson, Excerpta Medica, Ortho‐McNeil‐Jannsen, Sanofi Aventis, CardioInsight Technologies, InfoBionic, SIEMENS, Medtronic, Inc., CardioDx, Inc., CardioInsight Technologies, FoxP2 Medica, Mediasphere Medical, Wiley‐Blackwell, St. Jude Medical, Endosense, Thermedical, EP Advocate LLC, Hansen Medical, American Heart Association, EpiEP, NIH
WE‐EF‐303‐03: A New Aperture‐Based Imaging System for Prompt‐Gamma Range Verification of Proton Beam Therapy
Authors: Ready J , Pak R , Mihailescu L , Vetter K
Published: June 2015

Purpose:

To develop and characterize a novel aperture‐based imaging system for high‐energy gamma‐rays. This collimated system will provide 2‐dimensional imaging capability for verification of proton beam range and Bragg peak dose via prompt‐gamma detection.

Methods:

A multi‐knife‐edge slit collimator has been designed, constructed, and characterized via simulations and experimental measurements. The 20×20×7.5 cm3 tungsten collimator and accompanying LSO scintillation detector were simulated using the TOPAS Geant4 ‐based Monte Carlo package. Iterative reconstruction methods were combined with point response functions to characterize the imaging performance of the system. The response of the system has begun to be characterized experimentally as well, using 2.6 MeV gamma‐rays from Th‐228.

Results:

Both simulation and experimental results indicate that this collimated system provides 2‐D imaging capability in the energy range of interest for prompt‐gamma dose verification. In the current configuration, with collimator to source distance of 13 cm, image reconstruction of point sources resulted in spatial resolution (FWHM) of approximately 4 mm in both x‐and y‐directions in the imaging plane. The accuracy of positioning the point sources is less than 1 mm.

Conclusion:

This work has characterized, via simulation and measurements, a novel multi‐knife‐edge slit collimator in front of a more conventional position‐sensitive LSO scintillator detector. The multi‐slit pattern is designed to increase detection efficiency and provide spatial information in 2‐dimensions ‐‐ an improvement over a single‐slit collimator design. The thickness and density of the collimator will allow this detection system to perform well in an environment with high gamma flux, while ultimately providing peak determination accuracy on the order of 1 mm.

This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number: DE‐NA0000979 through the Nuclear Science and Security Consortium.
WE‐EF‐303‐05: Development and Commissioning of Real‐Time Imaging Function for Respiratory‐Gated Spot‐Scanning Proton Beam Therapy
Authors: Miyamoto N , Takao S , Matsuura T , Matsuzaki Y , Yamada T , Fujii Y , Matsuo Y , Kidani T , Egashira Y , Umekawa T , Shimizu S , Shirato H , Umegaki K
Published: June 2015

Purpose:

To realize real‐time‐image gated proton beam therapy (RGPT) for treating mobile tumors.

Methods:

The rotating gantry of spot scanning proton beam therapy has been designed to equip two x‐ray fluoroscopy devices that enable real‐time imaging of the internal fiducial markers during respiration. Three‐dimensional position of the fiducial marker located near the tumor can be calculated from the fluoroscopic images obtained from orthogonal directions and therapeutic beam is gated only when the fiducial marker is within the predefined gating window. Image acquisition rate can be selected from discrete value ranging from 0.1 Hz to 30 Hz. In order to confirm the effectiveness of RGPT and apply it clinically, clinical commissioning was conducted. Commissioning tests were categorized to main three parts including geometric accuracy, temporal accuracy and dosimetric evaluation.

Results:

Developed real‐time imaging function has been installed and its basic performances have been confirmed. In the evaluation of geometric accuracy, coincidence of three‐dimensional treatment room coordinate system and imaging coordinate system was confirmed to be less than 1 mm. Fiducial markers (gold sphere and coil) were able to be tracked in simulated clinical condition using an anthropomorphic chest phantom. In the evaluation of temporal accuracy, latency from image acquisition to gate on/off signal was about 60 msec in typical case. In dosimetric evaluation, treatment beam characteristics including beam irradiation position and dose output were stable in gated irradiation. Homogeneity indices to the mobile target were 0.99 (static), 0.89 (w/o gating, motion is parallel to direction of scan), 0.75 (w/o gating, perpendicular), 0.98 (w/ gating, parallel) and 0.93 (w/ gating, perpendicular). Dose homogeneity to the mobile target can be maintained in RGPT.

Conclusion:

Real‐time imaging function utilizing x‐ray fluoroscopy has been developed and commissioned successfully in order to realize RGPT.

Funding Support: This research was partially supported by Japan Society for the Promotion of Science (JSPS) through the FIRST Program. Conflict of Interest: Prof. Shirato has research fund from Hitachi Ltd, Mitsubishi Heavy Industries Ltd and Shimadzu Corporation.
WE‐EF‐204‐01: Pre‐Clinical Imaging for Co‐Clinical Trials
Authors: Hazle J.
Published: June 2015

As molecular biology breakthroughs in understanding cancers and other diseases, hundreds of new drugs wait testing. In the last decade, mouse models have been evolved to better mimic human diseases genetically and biologically. These reliable mouse models allow us to determine which genetic elements, pathways and mutations impact on therapy. The co‐clinical trial strategy is to conduct a human clinical trial for a therapeutic drug and test it in mouse models at the same time. This strategy has the potential to accelerate the drug testing process and identify the patient population that will respond to the drug. Imaging plays an important role in co‐clinical trials. In this symposium, four speakers will discuss advancements and issues in pre‐clinical imaging, murine models, imaging hardware and software, and funding opportunities in co‐clinical trials.

Learning Objectives:

Multi‐modality pre‐clinical imaging hardware and software, and new technologies (e.g., hyperpolarized MRI)

Selection of animal models from physiological and genetic perspectives with examples in colon, pancreatic and lung cancers

NCI funding opportunities
WE‐EF‐204‐02: Murine Model Systems for Co‐Clinical Trials
Authors: Manning H.
Published: June 2015

As molecular biology breakthroughs in understanding cancers and other diseases, hundreds of new drugs wait testing. In the last decade, mouse models have been evolved to better mimic human diseases genetically and biologically. These reliable mouse models allow us to determine which genetic elements, pathways and mutations impact on therapy. The co‐clinical trial strategy is to conduct a human clinical trial for a therapeutic drug and test it in mouse models at the same time. This strategy has the potential to accelerate the drug testing process and identify the patient population that will respond to the drug. Imaging plays an important role in co‐clinical trials. In this symposium, four speakers will discuss advancements and issues in pre‐clinical imaging, murine models, imaging hardware and software, and funding opportunities in co‐clinical trials.

Learning Objectives:

Multi‐modality pre‐clinical imaging hardware and software, and new technologies (e.g., hyperpolarized MRI)

Selection of animal models from physiological and genetic perspectives with examples in colon, pancreatic and lung cancers

NCI funding opportunities
WE‐EF‐207‐05: Monte Carlo Dosimetry for a Dedicated Cone‐Beam CT Head Scanner
Authors: Sisniega A , Zbijewski W , Xu J , Dang H , Stayman J W , Aygun N , Koliatsos V E , Wang X , Foos D H , Siewerdsen J H
Published: June 2015

Purpose:

Cone‐Beam CT (CBCT) is an attractive platform for point‐of‐care imaging of traumatic brain injury and intracranial hemorrhage. This work implements and evaluates a fast Monte‐Carlo (MC) dose estimation engine for development of a dedicated head CBCT scanner, optimization of acquisition protocols, geometry, bowtie filter designs, and patient‐specific dosimetry.

Methods:

Dose scoring with a GPU‐based MC CBCT simulator was validated on an imaging bench using a modified 16 cm CTDI phantom with 7 ion chamber shafts along the central ray for 80–100 kVp (+2 mm Al, +0.2 mm Cu). Dose distributions were computed in a segmented CBCT reconstruction of an anthropomorphic head phantom with 4×10⁵ tracked photons per scan (5 min runtime). Circular orbits with angular span ranging from short scan (180° + fan angle) to full rotation (360°) were considered for fixed total mAs per scan. Two aluminum filters were investigated: aggressive bowtie, and moderate bowtie (matched to 16 cm and 32 cm water cylinder, respectively).

Results:

MC dose estimates showed strong agreement with measurements (RMSE<0.001 mGy/mAs). A moderate (aggressive) bowtie reduced the dose, per total mAs, by 20% (30%) at the center of the head, by 40% (50%) at the eye lens, and by 70% (80%) at the posterior skin entrance. For the no bowtie configuration, a short scan reduced the eye lens dose by 62% (from 0.08 mGy/mAs to 0.03 mGy/mAs) compared to full scan, although the dose to spinal bone marrow increased by 40%. For both bowties, the short scan resulted in a similar 40% increase in bone marrow dose, but the reduction in the eye lens was more pronounced: 70% (90%) for the moderate (aggressive) bowtie.

Conclusions:

Dose maps obtained with validated MC simulation demonstrated dose reduction in sensitive structures (eye lens and bone marrow) through combination of short‐scan trajectories and bowtie filters.

Xiaohui Wang and David Foos are employees of Carestream Health
WE‐EF‐210‐03: Ultrasound‐Mediated Stimulation of Nanoparticles for Therapeutic Applications
Authors: Porter T.
Published: June 2015

Recent advances in ultrasound‐related technologies have had a significant impact on enhancing image quality as well as offering new approaches for quantitative ultrasonic imaging and therapeutic applications. The presentations associated with this session will provide an overview of advances in ultrasound image formation, the development of using nanoparticles for therapeutic ultrasound applications, as well as approaches for assessing the intrinsic viscoelastic properties of tissue and methods for monitoring tissue response to therapy.

Learning Objectives:

Develop a general understanding of new technologies associated with enhanced ultrasound image formation and volume imaging.

Develop an understanding of new ultrasound‐based technologies for quantitative assessment of intrinsic tissue properties.

Develop an understanding of novel approaches for ultrasound‐mediated non‐invasive therapeutic applications.

Dr. Rao is an employee of Siemens Ultrasound
WE‐E‐201‐03: Uncertainty and Issues in Biological Modeling for the Modern Medical Physicist
Authors: Altman M.
Published: June 2015

Physicists are often expected to have a solid grounding in experimental design and statistical analysis, sometimes filling in when biostatisticians or other experts are not available for consultation. Unfortunately, graduate education on these topics is seldom emphasized and few opportunities for continuing education exist. Clinical physicists incorporate new technology and methods into their practice based on published literature. A poor understanding of experimental design and analysis could Result in inappropriate use of new techniques. Clinical physicists also improve current practice through quality initiatives that require sound experimental design and analysis. Academic physicists with a poor understanding of design and analysis may produce ambiguous (or misleading) results. This can Result in unnecessary rewrites, publication rejection, and experimental redesign (wasting time, money, and effort).

This symposium will provide a practical review of error and uncertainty, common study designs, and statistical tests. Instruction will primarily focus on practical implementation through examples and answer questions such as: where would you typically apply the test/design and where is the test/design typically misapplied (i.e., common pitfalls)? An analysis of error and uncertainty will also be explored using biological studies and associated modeling as a specific use case.

Learning Objectives:

Understand common experimental testing and clinical trial designs, what questions they can answer, and how to interpret the results

Determine where specific statistical tests are appropriate and identify common pitfalls

Understand the how uncertainty and error are addressed in biological testing and associated biological modeling.
WE‐EF‐210‐02: Ultrasound Innovations in Therapy Response Monitoring
Authors: Czarnota G.
Published: June 2015

Recent advances in ultrasound‐related technologies have had a significant impact on enhancing image quality as well as offering new approaches for quantitative ultrasonic imaging and therapeutic applications. The presentations associated with this session will provide an overview of advances in ultrasound image formation, the development of using nanoparticles for therapeutic ultrasound applications, as well as approaches for assessing the intrinsic viscoelastic properties of tissue and methods for monitoring tissue response to therapy.

Learning Objectives:

Develop a general understanding of new technologies associated with enhanced ultrasound image formation and volume imaging.

Develop an understanding of new ultrasound‐based technologies for quantitative assessment of intrinsic tissue properties.

Develop an understanding of novel approaches for ultrasound‐mediated non‐invasive therapeutic applications.

Dr. Rao is an employee of Siemens Ultrasound
WE‐F‐201‐03: Evaluate Clinical Cases Using Commercially Available Systems and Compare to TG‐43 Dosimetry
Authors: Beaulieu L.
Published: June 2015

With the recent introduction of heterogeneity correction algorithms for brachytherapy, the AAPM community is still unclear on how to commission and implement these into clinical practice. The recently‐published AAPM TG‐186 report discusses important issues for clinical implementation of these algorithms. A charge of the AAPM‐ESTRO‐ABG Working Group on MBDCA in Brachytherapy (WGMBDCA) is the development of a set of well‐defined test case plans, available as references in the software commissioning process to be performed by clinical end‐users. In this practical medical physics course, specific examples on how to perform the commissioning process are presented, as well as descriptions of the clinical impact from recent literature reporting comparisons of TG‐43 and heterogeneity‐based dosimetry.

Learning Objectives:

Identify key clinical applications needing advanced dose calculation in brachytherapy.

Review TG‐186 and WGMBDCA guidelines, commission process, and dosimetry benchmarks.

Evaluate clinical cases using commercially available systems and compare to TG‐43 dosimetry