bluuebunny/crossref_metadata_2025_split huggingface dataset:
TU‐D‐BRB‐03: Dual‐Energy CT: Considerations in Radiation Therapy
Authors: Coolens C. 
Published: July 2016

Dual‐energy CT technology is becoming increasingly available to the medical imaging community. In addition, several models of CT simulators sold for use in radiation therapy departments now feature dual‐energy technology. The images provided by dual‐energy CT scanners add new information to the radiation treatment planning process; multiple spectral components can be used to separate and identify material composition as well as generate virtual monoenergetic images. In turn, this information could be used to investigate pathologic processes, separate the properties of contrast agents from soft tissues, assess tissue response to therapy, and other applications of therapeutic interest. Additionally, the decomposition of materials in images could directly integrate with and impact the accuracy of dose calculation algorithms.This symposium will explore methods of generating dual‐energy CT images, spectral and image analysis algorithms, current and future applications of interest in oncologic imaging, and unique considerations when using dualenergy CT images in the radiation treatment planning process.

Learning Objectives:
Understand acquisition techniques and processing algorithms used in dual‐energy CT imaging.
Discover current and future applications of dual‐energy CT images in the radiological oncology setting.
Introduce some of the unique considerations and QA requirements when integrating a dual‐energy CT scanner into the radiation therapy environment.N. Pelc: GE Healthcare, Philips Healthcare, Sony; U. Schoepf: Consultant for and / or research support from Astellas, Bayer,;Bracco, GE, Guerbet, Medrad, Siemens
TU‐D‐202‐00: Rest In Peace ‐ ITV
Authors: van Herk Marcel 
Published: July 2016

Respiratory motion has long been recognized as an important factor affecting the precision of radiotherapy. After the introduction of the 4D CT to visualize the respiratory motion in 3D, the internal target volume (ITV) has been widely adopted as simple method to take the motion into account in treatment planning and delivery. The ITV is generated as the union of the CTVs as the patient goes through the respiratory cycle. Many issues have been identified with the ITV. In this session three alternatives for the ITV will be discussed: 1) An alternative motion‐inclusive approach with better imaging and smaller margins, called mid‐position CT. 2) The tracking approach and 3) The gating approach.The following topics will be addressed by Marcel van Herk (“Is ITV the correct motion encompassing strategy”): Magnitude of respiratory motion, effect of motion on radiotherapy, motion encompassing strategies, and software solutions to assist in motion encompassing strategies. Then Paul Keall (“Make margins simple: Use real‐time target tracking”) will discuss tracking with: clinical drivers for tracking, current clinical status of tumor tracking, future tumor tracking technology, and margin margin challenges with and without tracking. Finally Daniel Low will discuss gating (“Gating is the best ITV killer”): why ITV in the first place, requirements for planning, requirements at the machine, benefits and costs.The session will end with a discussion and live demo of motion simulation software to illustrate the issues and explain the relative benefit and appropriate uses for the three methods.

Learning Objectives:
Explain the 4D imaging and treatment planning process.
Summarize the various approaches to deal with respiratory motion during radiotherapy
Discuss the tradeoffs involved when choosing one of the three discussed approaches.
Explain in which situation each method is the best choiceResearch is partly funded by Elekta Oncology Systems and the Dutch Cancer Foundation; M. van Herk, Part of the research was funded by Elekta Oncology Systems and the Dutch Cancer Foundation
TU‐D‐202‐02: Make Margins Simple: Use Real‐Time Target Tracking
Authors: Keall P. 
Published: July 2016

Respiratory motion has long been recognized as an important factor affecting the precision of radiotherapy. After the introduction of the 4D CT to visualize the respiratory motion in 3D, the internal target volume (ITV) has been widely adopted as simple method to take the motion into account in treatment planning and delivery. The ITV is generated as the union of the CTVs as the patient goes through the respiratory cycle. Many issues have been identified with the ITV. In this session three alternatives for the ITV will be discussed: 1) An alternative motion‐inclusive approach with better imaging and smaller margins, called mid‐position CT. 2) The tracking approach and 3) The gating approach.The following topics will be addressed by Marcel van Herk (“Is ITV the correct motion encompassing strategy”): Magnitude of respiratory motion, effect of motion on radiotherapy, motion encompassing strategies, and software solutions to assist in motion encompassing strategies. Then Paul Keall (“Make margins simple: Use real‐time target tracking”) will discuss tracking with: clinical drivers for tracking, current clinical status of tumor tracking, future tumor tracking technology, and margin margin challenges with and without tracking. Finally Daniel Low will discuss gating (“Gating is the best ITV killer”): why ITV in the first place, requirements for planning, requirements at the machine, benefits and costs.The session will end with a discussion and live demo of motion simulation software to illustrate the issues and explain the relative benefit and appropriate uses for the three methods.

Learning Objectives:
Explain the 4D imaging and treatment planning process.
Summarize the various approaches to deal with respiratory motion during radiotherapy
Discuss the tradeoffs involved when choosing one of the three discussed approaches.
Explain in which situation each method is the best choiceResearch is partly funded by Elekta Oncology Systems and the Dutch Cancer Foundation; M. van Herk, Part of the research was funded by Elekta Oncology Systems and the Dutch Cancer Foundation
TU‐D‐209‐04: How Useful Are Indirect Dose Metrics for Estimating Peak Skin Dose in Interventional Cardiology?
Authors: Jones A , Pasciak A 
Published: July 2016

Purpose:The purpose of this study was to determine if a relationship between indirect dose metrics and PSD could be established for fluoroscopically‐guided interventional cardiology procedures.Methods:PSD were measured directly using XR‐RV3 radiochromic film for 94 consecutive fluoroscopically guided interventional cardiology procedures performed at two sites. Procedures were both diagnostic and therapeutic in nature. Radiation dose structured reports (RDSR) were collected for each procedure and used to calculate indirect estimates of PSD which were compared to the measured PSD. Reference air kerma (Ka,r) was also compared to the measured PSD. Pearson's correlation coefficient was calculated for each metric and metrics were compared to measured PSD using a two‐tailed t‐test. Data were log transformed prior to statistical analysis.Results:Both Ka,r and the calculated PSD were closely correlated with measured PSD at each sites (Ka,r: 0.92 and 0.86, indirect PSD: 0.91 and 0.88). At one site, neither Ka,r nor indirect PSD was significantly different from the measured PSD (p = 0.22 and p=0.054, respectively), while at the second site both Ka,r and indirect PSD were significantly higher than measured PSD (p<0.0001 and p<0.0001, respectively). In almost all cases, both Ka,r and indirect PSD overestimated the true PSD.Conclusions:The use of a range of gantry angles and table positions, along with variation in procedural imaging requirements, limits the utility of indirect dose metrics for predicting PSD for interventional cardiology procedures.A. Kyle Jones and Alexander S. Pasciak are owners of Fluoroscopic Safety, LLC.
TU‐FG‐207B‐04: NCI Funding Opportunities in Imaging and Image‐Guided Therapy
Authors: Farahani K. 
Published: July 2016

Up‐to‐date knowledge about federal funding opportunities related to medical physics research, as well as obtaining skills for writing effective grant proposals are critical for academic and entrepreneurial medical physicists. In this symposium, program directors from key federal research funding agencies, including the National Cancer Institute, the National Institute of Biomedical Imaging and Bioengineering, and the National Science Foundation, will present information about current funding opportunities relevant to the field of medical physics. They will also provide insight to issues that applicants should pay special attention to when crafting their research grant proposals. In addition, the symposium will include presentations on research funding for small business concerns, and the results of an independent AAPM study of the National Institutes of Health funding of AAPM members from 2002–2015.

Learning Objectives:
To learn about current federal funding initiatives relevant to medical physics research
To learn about tactics important for crafting convincing research proposals
To learn about an independent study of NIH funding of research done by AAPM membersB. Whelan, this work was commissioned and funded by the AAPM
TU‐H‐BRC‐01: A New Fabrication Method for Secondary Skin Collimation Using 3D Scanner and 3D Printer
Authors: Jung J , Potter N , Suh T , Liu C , Lu B 
Published: July 2016

Purpose:Using secondary skin collimation (SSC) to protect the critical organ surrounding the tumors is always desirable for electron and/or ortho‐voltage treatments. However, the time‐consuming and labor‐intensive fabrication processes of current method (manually fabricate the lead mask) restrict the general use of SSC. The aim of this study is to develop a new SSC fabrication method using 3D scanning and 3D printing technologies in order to largely decrease the human labor involvement and fabrication time, also improve the fabrication accuracy.Methods:First, the patient surface was scanned with a 3D scanner (Structure Sensor, Occipital, CO). The raw scan data was subsequently transferred to a 3D modeling software (Rhinoceros, Ver. 5.0, McNeel North America, Seattle, WA). The tumor contour was then digitized and shielding region was determined by clinicians in the same software. The corresponding SCC conformed to the skin surface was then automatically generated by the software with the proper shielding thickness. The shell of the SCC (with hollow inside) was consequently printed by a 3D printer (Lulzbot TAZ, Aleph Objects, CO) using plastic material. Finally, the hollow mold of SCC was filled up with a melted cerrobend alloy. Once the cerrobend alloy cooled down, the fabrication of SCC was accomplished.Results:The results indicated the proposed method can achieve a much shorter time on making a SCC compared with tradition fabrication method. The processes of making a skin contour model for patients have been eliminated with the new method. SCC created by the new method possessed better accuracy and better conformality to patient's skin contours.Conclusion:In this study, we have demonstrated a new method for the SCC fabrication. It is anticipated that our method can be an alternative way to replace conventional manual‐based methods for electron and/or ortho‐voltage SCC fabrication.This research was supported by the Global Ph.D. Fellowship Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (Grant No. 2015H1A2A1034071), Republic of Korea.
TU‐H‐204‐01: Work of ICRP in relation to activities of medical physicists
Authors: Rehani M. 
Published: July 2016

Since 1928, the International Commission on Radiological Protection (ICRP) has developed, maintained, and elaborated the International System of Radiological Protection used world‐wide as the common basis for radiological protection standards, legislation, guidelines, programs, and practice. ICRP provides and periodically revises radiation and tissue weighing factors, provides and updates recommended dose limits for occupational and public exposures, recommends dose levels for termination of pregnancy, and estimates threshold doses for tissue reactions (deterministic effects). ICRP developed the dose quantity “effective dose”.NCRP Council Committee 1 (CC‐1) is charged with developing recommendations for revising radiation protection guidance for the United States. Topics to be discussed include a summary of current ICRP guidance, NCRP CC‐1 directions, NRC regulatory changes on the horizon, and potential implications of radiation protection guidance changes on the practice of medicine. The opinions of AAPM members on potential changes are welcomed.NCRP Program Area Committee (PAC) 4 has oversight of activities in radiation protection in medicine, including protection of patients and training of health care workers. Documents have been published recently on diagnostic reference levels and achievable doses, health effects of preconception and prenatal radiation exposure, and administrative policies for quality assurance and peer review of tissue reactions associated with fluoroscopically guided interventions. Additional documents are in preparation.

Learning Objectives:
To understand the international system of radiation protection and learn about the work of the International Commission on Radiological Protection (ICRP) in relation to activities of medical physicists
To understand the ongoing work of NCRP in developing new guidance for radiation protection in the U.S.
To understand the ongoing work of NCRP in developing new recommendations for radiation protection in medicine.
To learn about other national organizations in US whose work plays a useful role in the activities of medical physicists.M. Rehani, Work done as part of being member of ICRP. ICRP is an independent charity.
TU‐H‐201‐03: Panel Discussion Member
Authors: Palta J. 
Published: July 2016

The New New Symposium is a symposium for members relatively new to the organization to learn about the organizational structure and operational procedures of the society; how decisions are made, how the council and committee leadership is appointed and operates, opportunities for volunteer involvement, and a brief overview of the services and efforts provided by the HQ staff and the website. Attendees will hear from council chairs, key staff and chairs, and members with volunteer experience.After the symposium a social hour ensues with opportunities to interact with key AAPM members. The New Member Symposium is a (free) ticket option when you register online for the Annual Meeting. And don't forget registrants receive one (free) ticket for a beverage of your choice during the social afterwards.
TU‐H‐BRC‐08: Use and Validation of Flexible 3D Printed Tissue Compensators for Post‐Mastectomy Radiation Therapy
Authors: Craft D , Woodward W , Kanke J , Kry S , Salehpour M , Howell R 
Published: July 2016

Purpose:Patient‐specific tissue equivalent compensators can be used for post‐mastectomy radiation therapy (PMRT) to achieve homogenous dose distributions with single‐field treatments. However, current fabrication methods are time consuming and expensive. 3D‐printing technology could overcome these limitations. The purposes of this study were to [1] evaluate materials for 3D‐printed compensators [2] design and print a compensator to achieve a uniform thickness to a clinical target volume (CTV), and [3] demonstrate that a single‐field electron compensator plan is a clinically feasible treatment option for PMRT.Methods:Blocks were printed with three materials; print accuracy, density, Hounsfield units (HU), and percent depth doses (PDD) were evaluated. For a CT scan of an anthropomorphic phantom, we used a ray‐tracing method to design a compensator that achieved uniform thickness from compensator surface to CTV. The compensator was printed with flexible tissue equivalent material whose physical and radiological properties were most similar to soft tissue. A single‐field electron compensator plan was designed and compared with two standard‐of‐care techniques. The compensator plan was validated with thermoluminescent dosimeter (TLD) measurements.Results:We identified an appropriate material for 3D‐printed compensators that had high print accuracy (99.6%) and was similar to soft tissue; density was 1.04, HU was ‐ 45 ± 43, and PDD curves agreed with clinical curves within 3 mm. We designed and printed a compensator that conformed well to the phantom surface and created a uniform thickness to the CTV. In‐house fabrication was simple and inexpensive (<$75). Compared with the two standard plans, the compensator plan resulted in overall more homogeneous dose distributions and performed similarly in terms of lung/heart doses and 90% isodose coverage of the CTV. TLD measurements agreed well with planned doses (within 5 %).Conclusions:We have demonstrated that 3D‐printed compensators make single‐field electron therapy a clinically feasible treatment option for PMRT.
TU‐H‐BRA‐02: The Physics of Magnetic Field Isolation in a Novel Compact Linear Accelerator Based MRI‐Guided Radiation Therapy System
Authors: Low D , Mutic S , Shvartsman S , Chmielewski T , Fought G , Sharma A , Dempsey J 
Published: July 2016

Purpose:To develop a method for isolating the MRI magnetic field from field‐sensitive linear accelerator components at distances close to isocenter.Methods:A MRI‐guided radiation therapy system has been designed that integrates a linear accelerator with simultaneous MR imaging. In order to accomplish this, the magnetron, port circulator, radiofrequency waveguide, gun driver, and linear accelerator needed to be placed in locations with low magnetic fields. The system was also required to be compact, so moving these components far from the main magnetic field and isocenter was not an option. The magnetic field sensitive components (exclusive of the waveguide) were placed in coaxial steel sleeves that were electrically and mechanically isolated and whose thickness and placement were optimized using E&M modeling software. Six sets of sleeves were placed 60° apart, 85 cm from isocenter. The Faraday effect occurs when the direction of propagation is parallel to the magnetic RF field component, rotating the RF polarization, subsequently diminishing RF power. The Faraday effect was avoided by orienting the waveguides such that the magnetic field RF component was parallel to the magnetic field.Results:The magnetic field within the shields was measured to be less than 40 Gauss, significantly below the amount needed for the magnetron and port circulator. Additional mu‐metal was employed to reduce the magnetic field at the linear accelerator to less than 1 Gauss. The orientation of the RF waveguides allowed the RT transport with minimal loss and reflection.Conclusion:One of the major challenges in designing a compact linear accelerator based MRI‐guided radiation therapy system, that of creating low magnetic field environments for the magnetic‐field sensitive components, has been solved. The measured magnetic fields are sufficiently small to enable system integration.This work supported by ViewRay, Inc.
TU‐H‐BRA‐08: The Design and Characteristics of a Novel Compact Linac‐Based MRI Guided Radiation Therapy (MR‐IGRT) System
Authors: Mutic S , Low D , Chmielewski T , Fought G , Hernandez M , Kawrakow I , Sharma A , Shvartsman S , Dempsey J 
Published: July 2016

Purpose:To describe the design and characteristics of a novel linac‐based MRI guided radiation therapy system that addresses RF and magnetic field interference and that can be housed in conventional radiotherapy vaults.Methods:The MR‐IGRT system will provide simultaneous MR imaging combined with both simple (3D) and complex (IMRT, SBRT, SRS) techniques. The system is a combination of a) double‐donut split solenoidal superconducting 0.345T MRI; and b) a 90 cm isocenter ring‐gantry mounted 6MV, flattening filter‐free linac coupled with a stacked doubly‐focused multileaf collimator with 4 mm resolution. A novel RF shielding and absorption technology was developed to isolate the beam generating RF emissions from the MR, while a novel magnetic shielding sleeve system was developed to place the magnetic field‐sensitive components in low‐magnetic field regions. The system design produces high spatial resolution radiation beams with state‐of‐the art radiation dose characteristics and simultaneous MR imaging.Results:Prototype testing with a spectrum analyzer has demonstrated complete elimination of linac RF inside the treatment room. The magnetic field inside of the magnetic shielding was well below the specification, allowing the linear accelerator to operate normally. A novel on‐gantry shimming system maintained < 25 ppm magnetic field homogeneity over a 45 cm spherical field of view for all gantry angles.Conclusion:The system design demonstrates the feasibility coupling a state‐of‐the art linac system with a 0.345T MRI, enabling highly conformal radiation therapy with simultaneous MR image guidance.S. Mutic's employer (Washington University) has grant with ViewRay; D. Low is former ViewRay scientific advisory board member (ended October 2015); T. Chmielewski, G. Fought, M. Hernandez, I. Kawrakow, A. Sharma, S. Shvartsman, J. Dempsey are employees of ViewRay with stock options (Dempsey has leadership role and Dempsey/Kawrakow have stock).
TU‐H‐BRA‐09: Relationship Between B0 and the Contrast‐To‐Noise Ratio (CNR) of Tumour to Background for MRI/Radiotherapy Hybrids
Authors: Wachowicz K , DeZanche N , Yip E , Volotovskyy V , Fallone B 
Published: July 2016

Purpose:To investigate the relationship in MRI between B0 and the contrast‐to‐noise ratio (CNR) of various tumour/normal tissue pairs. This study is motivated by the current interest in MRI/radiotherapy hybrids, for which multiple magnetic field strengths have been proposed. CNR is the single most important parameter governing the ability of a system to identify a tumour in real time for treatment guidance. The MRI community has long since recognized that the SNR of a well‐designed MR system is roughly proportional to B0, the polarizing magnetic field. However, the CNR between two tissues is much more complicated ‐ dependent not only on this signal behavior, but also on the different relaxation properties of the tissues.Methods:Experimentally‐based models of B0‐dependant relaxation for various tumour and normal tissues from the literature were used in conjunction with signal equations for MR sequences suitable for rapid realtime imaging to develop field‐dependent predictions for CNR. These CNR models were developed for liver, lung, breast, glioma, and kidney tumours for spoiled‐gradient echo (SGE) and balanced steady‐state free precession (bSSFP) sequences.Results:In all cases there was an improved CNR at lower fields compared to linear dependency. Further, in some tumour sites, the CNR at lower fields was found to be comparable to, or sometimes higher than those at higher fields (i.e. bSSFP CNR for glioma, kidney and liver tumours).Conclusion:Due to the variation of tissue relaxation parameters with field, lower B0 fields have been shown to perform as well or better (in terms of CNR) than higher fields for some tumour sites. In other sites this effect was less pronounced. It is the complex relationship between CNR and B0 that leads to greater CNR at 0.5 T for certain tumour types studied here for fast imaging.B. Gino Fallone is a co‐founder and CEO of MagnetTx Oncology Solutions (under discussions to license Alberta bi‐planar linac MR for commercialization)