bluuebunny/crossref_metadata_2025 huggingface dataset:
TU‐H‐BRB‐03: The BARDA Chemical/Radiological/Nuclear Countermeasures Effort
Authors: Hu T.
Published: July 2016

The US government has substantial research and development activities underway for medical countermeasures that will insure the long‐term safety and survival of the country's population after unfortunate large‐scale biological, chemical and radiological and nuclear events. Preparedness includes research and development of medical countermeasures to address radiation‐induced cutaneous and internal injury from radiation and nuclear events as well as for minimizing radiation risks incurred during and after travel in space. Other important research and development efforts include the repurposing of countermeasures and development of radioprotectors and mitigators to improve the outcome of radiation treatment. Participating agencies include NIAID, BARDA, NCI, and NASA, with examples of research and development funding that includes the Centers for Medical Countermeasures against Radiation (CMCR) consortia (NIAID) and primary and sub‐contracts with commercial entities (BARDA). Each of these programs requires substantial medical and health physics effort in collaboration with biology colleagues to provide a range of radiation sources, dosimetry instrumentation and assessment methods, and animal models for specific radiation‐induced effects and injuries. Radiation countermeasure activities for government agencies will be reviewed, the importance of model development will be stressed, example radiation countermeasure research projects will be reviewed, and the roles for medical physicists will be discussed.

Learning Objectives:

Review US national radiation countermeasure activities.

Review the roles for medical physicists in radiation countermeasures research and development.

Understand specific physics challenges in radiation research that need solutions.

Research for JD Bourland supported in part by: NIH/NIAID, U19 AI67798 (subcontract 131714). NIH/NCI, R01CA155293. HHSO10020130019C, BARDA/Argentum Medical LLC.; J. Bourland, Research supported in part by:

NIH/NIAID, U19 AI67798 (subcontract 131714); NIH/NCI, R01CA155293; HHSO10020130019C, BARDA/Argentum Medical LLC.; P. Prasanna, Supported by the Radiation Research Program, National Cancer Institute
TU‐H‐BRB‐04: Radiation Countermeasures and the NCI Radiation Research Program
Authors: Prasanna P.
Published: July 2016

The US government has substantial research and development activities underway for medical countermeasures that will insure the long‐term safety and survival of the country's population after unfortunate large‐scale biological, chemical and radiological and nuclear events. Preparedness includes research and development of medical countermeasures to address radiation‐induced cutaneous and internal injury from radiation and nuclear events as well as for minimizing radiation risks incurred during and after travel in space. Other important research and development efforts include the repurposing of countermeasures and development of radioprotectors and mitigators to improve the outcome of radiation treatment. Participating agencies include NIAID, BARDA, NCI, and NASA, with examples of research and development funding that includes the Centers for Medical Countermeasures against Radiation (CMCR) consortia (NIAID) and primary and sub‐contracts with commercial entities (BARDA). Each of these programs requires substantial medical and health physics effort in collaboration with biology colleagues to provide a range of radiation sources, dosimetry instrumentation and assessment methods, and animal models for specific radiation‐induced effects and injuries. Radiation countermeasure activities for government agencies will be reviewed, the importance of model development will be stressed, example radiation countermeasure research projects will be reviewed, and the roles for medical physicists will be discussed.

Learning Objectives:

Review US national radiation countermeasure activities.

Review the roles for medical physicists in radiation countermeasures research and development.

Understand specific physics challenges in radiation research that need solutions.

Research for JD Bourland supported in part by: NIH/NIAID, U19 AI67798 (subcontract 131714). NIH/NCI, R01CA155293. HHSO10020130019C, BARDA/Argentum Medical LLC.; J. Bourland, Research supported in part by:

NIH/NIAID, U19 AI67798 (subcontract 131714); NIH/NCI, R01CA155293; HHSO10020130019C, BARDA/Argentum Medical LLC.; P. Prasanna, Supported by the Radiation Research Program, National Cancer Institute
TU‐H‐BRB‐05: Radiation Countermeasures and the NASA Space Radiation Program
Authors: Huff J.
Published: July 2016

The US government has substantial research and development activities underway for medical countermeasures that will insure the long‐term safety and survival of the country's population after unfortunate large‐scale biological, chemical and radiological and nuclear events. Preparedness includes research and development of medical countermeasures to address radiation‐induced cutaneous and internal injury from radiation and nuclear events as well as for minimizing radiation risks incurred during and after travel in space. Other important research and development efforts include the repurposing of countermeasures and development of radioprotectors and mitigators to improve the outcome of radiation treatment. Participating agencies include NIAID, BARDA, NCI, and NASA, with examples of research and development funding that includes the Centers for Medical Countermeasures against Radiation (CMCR) consortia (NIAID) and primary and sub‐contracts with commercial entities (BARDA). Each of these programs requires substantial medical and health physics effort in collaboration with biology colleagues to provide a range of radiation sources, dosimetry instrumentation and assessment methods, and animal models for specific radiation‐induced effects and injuries. Radiation countermeasure activities for government agencies will be reviewed, the importance of model development will be stressed, example radiation countermeasure research projects will be reviewed, and the roles for medical physicists will be discussed.

Learning Objectives:

Review US national radiation countermeasure activities.

Review the roles for medical physicists in radiation countermeasures research and development.

Understand specific physics challenges in radiation research that need solutions.

Research for JD Bourland supported in part by: NIH/NIAID, U19 AI67798 (subcontract 131714). NIH/NCI, R01CA155293. HHSO10020130019C, BARDA/Argentum Medical LLC.; J. Bourland, Research supported in part by:

NIH/NIAID, U19 AI67798 (subcontract 131714); NIH/NCI, R01CA155293; HHSO10020130019C, BARDA/Argentum Medical LLC.; P. Prasanna, Supported by the Radiation Research Program, National Cancer Institute
TU‐H‐BRA‐03: Performance of a Clinical Gridded Electron Gun in Magnetic Fields: Implications for MRI‐Linac Therapy
Authors: Whelan B , Bazalova‐Carter M , Oborn B , Constantin D , Holloway L , Fahrig R , Keall P
Published: July 2016

Purpose:

Recent advances towards MRI Linac radiotherapy have motivated a wide range of studies characterizing electromagnetic interactions between the two devices. One of the most sensitive components is the linac electron gun. To data, only non gridded (diode) guns have been investigated however, most linac vendors utilize gridded (triode) guns, which enable efficient and robust beam gating. The purpose of this study was to develop a realistic model of a gridded gun used clinically, and to characterize its performance in magnetic fields.

Methods:

The gridded electron gun used on Varian high energy machines was measured using 3D laser scanning quoted as accurate to 0.1mm. Based on the scane, a detailed CAD mode was developed. From this, key geometry was extracted and a FEM model was developed (Opera/SCALA). Next, the high voltage (HV), grid voltage, and emission current were read from six dose matched TrueBeam linacs for the 6X, 10X and 15X photon modes (0 B‐field). The mean values were used to represent each mode, which was simulated I constant magnetic fields from 0–200G in‐line, and 0–35G perpendicular.

Results:

Experimentally measured HV, grid voltage, and emission current from 6X, 10X and 15X modes were respectively: 15±.03kV, 10±.08kV, 11±.03kV; 93±7V, 41±3V, and 70±6V; 327±27mA, 129±10mA, and 214±19mA. The error in simulated emission current of each mode was 3%,6%, and 3%. For in‐line fields, 50% beam loss occurred at 114, 96, and 97G; for perpendicular; at 12, 13 and 14G. Sensitivity for a given geometry is primarily determined by HV setting.

Conclusion:

Future MRI‐Linac systems will almost certainly use gridded guns. We present the first model of a clinical gridded gun, and match the experimental emission current to within 6% across three different operating modes. This clinical gun shows increased sensitivity to magnetic fields than previous work,and different modes show different sensitivity.
TU‐H‐BRA‐06: Characterization of a Linear Accelerator Operating in a Compact MRIGuided Radiation Therapy System
Authors: Green O , Mutic S , Low D , Li H , Chmielewski T , Fought G , Hernandez M , Kawrakow I , Sharma A , Shvartsman S , Dempsey J
Published: July 2016

Purpose:

To describe the performance of a linear accelerator operating in a compact MRI‐guided radiation therapy system.

Methods:

A commercial linear accelerator was placed in an MRI unit that is employed in a commercial MR‐based image guided radiation therapy (IGRT) system. The linear accelerator components were placed within magnetic field‐reducing hardware that provided magnetic fields of less than 40 G for the magnetron, gun driver, and port circulator, with 1 G for the linear accelerator. The system did not employ a flattening filter. The test linear accelerator was an industrial 4 MV model that was employed to test the ability to run an accelerator in the MR environment. An MR‐compatible diode detector array was used to measure the beam profiles with the accelerator outside and inside the MR field and with the gradient coils on and off to examine if there was any effect on the delivered dose distribution. The beam profiles and time characteristics of the beam were measured.

Results:

The beam profiles exhibited characteristic unflattened Bremsstrahlung features with less than ±1.5% differences in the profile magnitude when the system was outside and inside the magnet and less than 1% differences with the gradient coils on and off. The central axis dose rate fluctuated by less than 1% over a 30 second period when outside and inside the MRI.

Conclusion:

A linaccompatible MR design has been shown to be effective in not perturbing the operation of a commercial linear accelerator. While the accelerator used in the tests was 4MV, there is nothing fundamentally different with the operation of a 6MV unit, implying that the design will enable operation of the proposed clinical unit.

Research funding provided by ViewRay, Inc.
TU‐H‐202‐00: CT Ventilation Imaging: The New Clinical Reality of Functional Avoidance and Response Assessment in Lung Cancer Radiation Therapy
Authors: Keall Paul
Published: July 2016

CT ventilation imaging is an exciting functional imaging modality that combines four‐dimensional computed tomography (4DCT) and deformable image registration (DIR) to provide exquisite ventilation maps of the lung. CT ventilation imaging can be used for:

Functional avoidance in thoracic radiation therapy,

Imaging longitudinal changes in regional lung function for treatment assessment and adaptation,

Image‐assisted diagnosis of non‐oncologic respiratory diseases.

CT ventilation imaging uses CT, a predominantly anatomic imaging modality, and through imaging processing creates functional images. CT ventilation imaging provides functional images that are higher resolution, faster and cheaper to perform than the clinical standard, SPECT. Indeed the number of CT ventilation abstracts presented at the AAPM meeting has been doubling every two years. With the world's‐first clinical trial of CT ventilation functional image‐guided radiation therapy now underway, the first dedicated scientific symposium will educate and stimulate AAPM members from both radiology and radiation oncology.

This symposium will compare the foundations of CT ventilation imaging with competing MRI, PET and SPECT ventilation imaging methods, and details the first clinical trial of CT ventilation imaging for functional avoidance in lung cancer radiation therapy. The spatial‐temporal nature of pulmonary ventilation, response maps to radiation and the design of predictive models will be presented. Validation efforts and challenges will also be discussed, from clinical outcome correlations in single time point and longitudinal studies, to cross‐modality image comparisons in the first multi‐institutional CT ventilation imaging challenge.

The panel will discuss the future role of CT ventilation imaging, and what level of physiologic validation is needed for applications in radiation oncology and beyond.

Learning Objectives:

Learn the principles of CT ventilation imaging and how ventilation images are acquired with MRI, PET and SPECT

Understand the methods used to benchmark CT ventilation and the correlations between CT ventilation imaging and clinical outcomes

Recognize the clinical applications of CT ventilation imaging in radiation oncology and beyond

Australian NHMRC Fellowship. Australian NSW Cancer Institute Fellowship.; Y. Vinogradskiy, The authors acknowledge NIH R01CA200817 grant and Stat of Colorado grant.; T. Yamamoto, This study was supported in part by the American Cancer Society and the Dean of the University of California Davis School of Medicine (ACS IRG‐95‐125‐13). Philips Radiation Oncology Systems loaned us a research version of the Pinnacle3 treatment planning system.; J. Bayouth, Funding support from NCI

R01 CA166703; J. Kipritidis, This work has been supported by a Cancer Institute NSW Early Career Fellowship and an NHMRC Australia Fellowship.

No commercial funding was received for this work.
TU‐H‐207A‐05: Automated Early Identification of An Excessive Air‐In‐Oil X‐Ray Tube Artifact That Mimics Acute Cerebral Infarct
Authors: Winslow J , Zhang Y , Samei E
Published: July 2016

Purpose:

There is an infrequent but serious CT artifact that occurs when there is too much air in the cooling oil of an x‐ray tube. This artifact manifests as patchy hypodensities and mimics acute cerebral infarct. Routine quality control testing is unlikely to detect this artifact before it is observed in patient images. The purpose of this project was to develop an automated, quantitative method that increased the likelihood of identifying and preventing such artifacts.

Methods:

Using QC phantom images with a known air‐in‐oil artifact, a 1D radial representation of the 2D noise power spectrum(NPS) was calculated and compared against that for artifact‐free images. The QC program software used at our institution to analyze daily phantom images was modified to include measuring the average frequency of NPS within the water section of daily phantom scans. The threshold values developed for each CT system were incorporated into our daily QC program and email notification system.

Results:

The NPS for the known air‐in‐oil artifact images included a large low frequency peak compared with artifact‐free images; the average NPS frequency for these images were 0.197 and 0.319 (1/mm), respectively. The average NPS frequency values (mean+/− standard deviation) for the GE CT750, GE VCT, GE Lightspeed Xtra, and Siemens SOMATOM Definition Flash scanners were 0.322+/− 0.0058, 0.324+/−0.0024, 0.320+/−0.0020, and 0.303+/−0.0039 (1/mm), respectively. Threshold values were chosen to be the average plus or minus twice the standard deviation. Automated QC successfully identified an air‐in‐oil artifact in the Lightspeed Xtra before any detrimental clinical effect occurred; the average NPS frequency value that triggered service was 0.307, which is six standard deviations smaller than average.

Conclusion:

Clinically serious problems associated with the air‐in‐oil artifact can be detected earlier and mitigated/avoided by incorporating the average frequency of NPS measurements of daily phantom images into an automated QC program.
TU‐H‐207A‐09: An Automated Technique for Estimating Patient‐Specific Regional Imparted Energy and Dose From TCM CT Exams Across 13 Protocols
Authors: Sanders J , Tian X , Segars P , Boone J , Samei E
Published: July 2016

Purpose:

To develop an automated technique for estimating patient‐specific regional imparted energy and dose from tube current modulated (TCM) computed tomography (CT) exams across a diverse set of head and body protocols.

Methods:

A library of 58 adult computational anthropomorphic extended cardiac‐torso (XCAT) phantoms were used to model a patient population. A validated Monte Carlo program was used to simulate TCM CT exams on the entire library of phantoms for three head and 10 body protocols. The net imparted energy to the phantoms, normalized by dose length product (DLP), and the net tissue mass in each of the scan regions were computed. A knowledgebase containing relationships between normalized imparted energy and scanned mass was established. An automated computer algorithm was written to estimate the scanned mass from actual clinical CT exams. The scanned mass estimate, DLP of the exam, and knowledgebase were used to estimate the imparted energy to the patient. The algorithm was tested on 20 chest and 20 abdominopelvic TCM CT exams.

Results:

The normalized imparted energy increased with increasing kV for all protocols. However, the normalized imparted energy was relatively unaffected by the strength of the TCM. The average imparted energy was 681 ± 376 mJ for abdominopelvic exams and 274 ± 141 mJ for chest exams. Overall, the method was successful in providing patientspecific estimates of imparted energy for 98% of the cases tested.

Conclusion:

Imparted energy normalized by DLP increased with increasing tube potential. However, the strength of the TCM did not have a significant effect on the net amount of energy deposited to tissue. The automated program can be implemented into the clinical workflow to provide estimates of regional imparted energy and dose across a diverse set of clinical protocols.
TU‐H‐206‐01: An Automated Approach for Identifying Geometric Distortions in Gamma Cameras
Authors: Mann S , Nelson J , Samei E
Published: July 2016

Purpose:

To develop a clinically‐deployable, automated process for detecting artifacts in routine nuclear medicine (NM) quality assurance (QA) bar phantom images.

Methods:

An artifact detection algorithm was created to analyze bar phantom images as part of an ongoing QA program. A low noise, high resolution reference image was acquired from an x‐ray of the bar phantom with a Philips Digital Diagnost system utilizing image stitching. NM bar images, acquired for 5 million counts over a 512×512 matrix, were registered to the template image by maximizing mutual information (MI). The MI index was used as an initial test for artifacts; low values indicate an overall presence of distortions regardless of their spatial location. Images with low MI scores were further analyzed for bar linearity, periodicity, alignment, and compression to locate differences with respect to the template. Findings from each test were spatially correlated and locations failing multiple tests were flagged as potential artifacts requiring additional visual analysis. The algorithm was initially deployed for GE Discovery 670 and Infinia Hawkeye gamma cameras.

Results:

The algorithm successfully identified clinically relevant artifacts from both systems previously unnoticed by technologists performing the QA. Average MI indices for artifact‐free images are 0.55. Images with MI indices < 0.50 have shown 100% sensitivity and specificity for artifact detection when compared with a thorough visual analysis. Correlation of geometric tests confirms the ability to spatially locate the most likely image regions containing an artifact regardless of initial phantom orientation.

Conclusion:

The algorithm shows the potential to detect gamma camera artifacts that may be missed by routine technologist inspections. Detection and subsequent correction of artifacts ensures maximum image quality and may help to identify failing hardware before it impacts clinical workflow. Going forward, the algorithm is being deployed to monitor data from all gamma cameras within our health system.
TU‐H‐206‐03: Characterizing B1 Inhomogeneities in DCE MRI
Authors: Gach H , Mason N
Published: July 2016

Purpose:

Dynamic Contrast Enhanced (DCE) MRI is a valuable technique for measuring perfusion and permeability characteristics of tumors. Exogenous contrast concentrations are calculated based on changes in T1 measured using fast 3D gradient echo (FLASH) sequences. However, the slab selective pulses used in 3D MRI may result in B1 inhomogeneities across the volume of interest that can lead to errors in T1 and thus the estimated gadolinium concentration. We compared three FLASH DCE sequences (GRE, TWIST, and VIBE) to determine their signal homogeneity across slices and the accuracy in calculating T1 using acquisitions with variable flip angles.

Methods:

The sequences were tested at 3 T on a Siemens mMR (VB20P) using a doped water phantom 3.75 g/L NiSO4 ‐ 6H2O + 5 g/L NaCl (T1 = 104 ms) and a 2% agar, 0.67% NaCl phantom (T1= 1.71 s). 2D EPI B1 maps and inversion recovery T1maps were acquired for ground truth. 3D MRI was acquired at different flip angles to generate a T1 map. Regions of interest were drawn to measure signal inside the phantoms as a function of slice position. The T1 for each slice ROI was fit to the FLASH steady‐state model of magnetization.

Results:

Based on the data, GRE gave the most uniform signal homogeneity and T1 values in the middle slices of the 3D volume. The 3D VIBE sequence had the largest region of signal inhomogeneity compared to the 3D GRE and TWIST sequences. VIBE's B1 inhomogeneity is inconsistent at low flip angles. However, VIBE resulted in more slices with T1 values similar to the ground truth.

Conclusion:

The central 1/3 of the slices yielded signals that result in T1 fits consistent with the ground truth. However, the remaining slices required some form of B1 inhomogeneity correction for quantitative DCE analysis.

The research was supported in part by NIH NCI Grant R01CA159471.
TU‐H‐209‐00: Planning and Delivering HDR APBI Treatments
Authors: Bacala Angelina
Published: July 2016

Learnings Objectives:

Although brachytherapy is the oldest form of radiation therapy, the rapid advancement of the methods of dose calculation, treatment planning and treatment delivery pushes us to keep updating our knowledge and experience to new procedures all the time. Our purpose is to present the newest applicators used in Accelerated Partial Breast Irradiation (APBI) and the techniques of using them for a maximum effective treatment. Our objective will be to get the user familiar with the Savi, Contura and ML Mammosite from the detailed description and measurements to cavity eval and choice or size, to acceptance tests and use of each.

At the end of the session the attendants will be able to assist at the scanning of the patient for the first treatment, decide on the proper localization and immobilization devices, import the scans in the treatment planning system, perform the structure segmentation, reconstruct the catheters and develop a treatment plan using inverse planning (IPSA) or volume optimization. The attendant should be able to evaluate the quality of a treatment plan according to the ABS protocols and B39 after this session.

Our goal is that all the attendants to gain knowledge of all the quality assurance procedures required to be performed prior to a treatment, at the beginning of a treatment day, weekly, monthly and annualy on the remote afterloader, the treatment planning system and the secondary check system. We will provide tips for a consistent treatment delivery of the 10 fractions in a BID (twice daily) regimen.
TU‐H‐207B‐00: Moving Radiomics Forward: Funding, Regulatory Issues, and Clinical Translation
Authors: Myers Kyle
Published: July 2016

Research and development in radiomics for precision medicine have been advancing at a rapid pace, and can be extended to eventually be mature enough for integration into clinical practice. To facilitate advances in this field, investigators need updated information on research funding, regulatory matters, and clinical translation efforts. In this special radiomics symposium, the attendee will learn of various novel funding mechanisms – both past and present – that have been used to support a number of quantitative imaging and radiomics research and resource infrastructures. In addition, a regulatory presentation will be given to provide the attendee with an understanding of when a radiomics tool might require FDA clearance or approval, and with what supporting performance data. We will end with insights from a clinical radiologist who is greatly involved in quantitative imaging in order to enable the attendee to appreciate the needs and subtleties involved in moving radiomics into the clinical workflow.

J. Boone, This is a memorial and not a funded event.
TU‐H‐207B‐01: Memorial Tribute
Authors: Boone J.
Published: July 2016

Research and development in radiomics for precision medicine have been advancing at a rapid pace, and can be extended to eventually be mature enough for integration into clinical practice. To facilitate advances in this field, investigators need updated information on research funding, regulatory matters, and clinical translation efforts. In this special radiomics symposium, the attendee will learn of various novel funding mechanisms – both past and present – that have been used to support a number of quantitative imaging and radiomics research and resource infrastructures. In addition, a regulatory presentation will be given to provide the attendee with an understanding of when a radiomics tool might require FDA clearance or approval, and with what supporting performance data. We will end with insights from a clinical radiologist who is greatly involved in quantitative imaging in order to enable the attendee to appreciate the needs and subtleties involved in moving radiomics into the clinical workflow.

J. Boone, This is a memorial and not a funded event.
TU‐H‐CAMPUS‐IeP1‐04: Combined Organ Dose for Digital Subtraction Angiography and Computed Tomography Using Monte Carlo Simulation
Authors: Sakabe D , Ohno T , Araki F , Hashida M , Funama Y
Published: July 2016

Purpose:

The purpose of this study was to evaluate the combined organ dose of digital subtraction angiography (DSA) and computed tomography (CT) using a Monte Carlo (MC) simulation on the abdominal intervention.

Methods:

The organ doses for DSA and CT were obtained with MC simulation and actual measurements using fluorescent‐glass dosimeters at 7 abdominal portions in an Alderson‐Rando phantom. DSA was performed from three directions: posterior anterior (PA), right anterior oblique (RAO), and left anterior oblique (LAO). The organ dose with MC simulation was compared with actual radiation dose measurements. Calculations for the MC simulation were carried out with the GMctdospp (IMPS, Germany) software based on the EGSnrc MC code. Finally, the combined organ dose for DSA and CT was calculated from the MC simulation using the X‐ray conditions of a patient with a diagnosis of hepatocellular carcinoma.

Results:

For DSA from the PA direction, the organ doses for the actual measurements and MC simulation were 2.2 and 2.4 mGy/100 mAs at the liver, respectively, and 3.0 and 3.1 mGy/100 mAs at the spinal cord, while for CT, the organ doses were 15.2 and 15.1 mGy/100 mAs at the liver, and 14.6 and 13.5 mGy/100 mAs at the spinal cord. The maximum difference in organ dose between the actual measurements and the MC simulation was 11.0% of the spleen at PA, 8.2% of the spinal cord at RAO, and 6.1% of left kidney at LAO with DSA and 9.3% of the stomach with CT. The combined organ dose (4 DSAs and 6 CT scans) with the use of actual patient conditions was found to be 197.4 mGy for the liver and 205.1 mGy for the spinal cord.

Conclusion:

Our method makes it possible to accurately assess the organ dose to patients for abdominal intervention with combined DSA and CT.
TU‐H‐CAMPUS‐JeP1‐02: Fully Automatic Verification of Automatically Contoured Normal Tissues in the Head and Neck
Authors: McCarroll R , Beadle B , Yang J , Zhang L , Mejia M , Kisling K , Balter P , Stingo F , Nelson C , Followill D , Court L
Published: July 2016

Purpose:

To investigate and validate the use of an independent deformable‐based contouring algorithm for automatic verification of auto‐contoured structures in the head and neck towards fully automated treatment planning.

Methods:

Two independent automatic contouring algorithms [(1) Eclipse's Smart Segmentation followed by pixel‐wise majority voting, (2) an in‐house multi‐atlas based method] were used to create contours of 6 normal structures of 10 head‐and‐neck patients. After rating by a radiation oncologist, the higher performing algorithm was selected as the primary contouring method, the other used for automatic verification of the primary. To determine the ability of the verification algorithm to detect incorrect contours, contours from the primary method were shifted from 0.5 to 2cm. Using a logit model the structure‐specific minimum detectable shift was identified. The models were then applied to a set of twenty different patients and the sensitivity and specificity of the models verified.

Results:

Per physician rating, the multi‐atlas method (4.8/5 point scale, with 3 rated as generally acceptable for planning purposes) was selected as primary and the Eclipse‐based method (3.5/5) for verification. Mean distance to agreement and true positive rate were selected as covariates in an optimized logit model. These models, when applied to a group of twenty different patients, indicated that shifts could be detected at 0.5cm (brain), 0.75cm (mandible, cord), 1cm (brainstem, cochlea), or 1.25cm (parotid), with sensitivity and specificity greater than 0.95. If sensitivity and specificity constraints are reduced to 0.9, detectable shifts of mandible and brainstem were reduced by 0.25cm. These shifts represent additional safety margins which might be considered if auto‐contours are used for automatic treatment planning without physician review.

Conclusion:

Automatically contoured structures can be automatically verified. This fully automated process could be used to flag auto‐contours for special review or used with safety margins in a fully automatic treatment planning system.
TU‐H‐CAMPUS‐TeP1‐05: Fast Processed 3D Printing‐Aided Urethane Resin (PUR) Bolus in Radiation Therapy
Authors: Zhao B , Chiu T , Gu X , Lee H , Nedzi L , Jiang S
Published: July 2016

Purpose:

3D printed custom bolus is regularly used in radiation therapy clinic as a compensator. However, usual method of bolus printing with 100% filling is very time‐consuming. The purpose of this study is to evaluate the feasibility and benefit of 3D printed bolus filled with UR.

Methods:

Two boluses were designed on nose (9e electrons) and ear (6× photons) for a head phantom in treatment planning system (TPS) to achieve dose coverage to the skin. The bolus structures (56–167cc) were converted to STereoLithographic (STL) model using an in‐house developed algorithm and sent to a commercial fused deposition modeling (FDM) printer. Only shells were printed with polylactic acid (PLA) material. Liquid UR was then placed in a vacuum pump and slowly poured into the hollow bolus from its top opening. Liquid UR hardened in around half an hour. The phantom was rescanned with custom boluses attached and the dosimetry was compared with original design in TPS. Basic CT and dose properties were investigated. GaF films were irradiated to measure dose profile and output of several open photon and electron beams under solid water and UR slabs of same thicknesses.

Results:

CT number was 11.2±7.3 and 65.4±7.8, respectively for solid water(∼1.04g/cc) and UR(∼1.08g/cc). The output measurement at dmax for 6× was within 2% for the two materials. The relative dose profiles of the two materials above dmax show 94–99% Gamma analysis passing rates for both photons and electrons. Dose distributions with 3D PUR boluses maintained great coverage on the intended skin regions and resembled that with computer generated boluses. Manufacturing 3D PUR boluses was 3–4 times faster than 100% printed boluses. The efficiency significantly improves for larger boluses.

Conclusion:

The study suggests UR has similar dose responses as solid water. Making custom bolus with UR greatly increases clinical workflow efficiency.
TU‐H‐CAMPUS‐IeP2‐01: Quantitative Evaluation of PROPELLER DWI Using QIBA Diffusion Phantom
Authors: Yung J , Ai H , Liu H , Stafford R
Published: July 2016

Purpose:

The purpose of this study is to determine the quantitative variability of apparent diffusion coefficient (ADC) values when varying imaging parameters in a diffusion‐weighted (DW) fast spin echo (FSE) sequence with Periodically Rotated Overlapping ParallEL Lines with Enhanced Reconstruction (PROPELLER) k‐space trajectory.

Methods:

Using a 3T MRI scanner, a NIST traceable, quantitative magnetic resonance imaging (MRI) diffusion phantom (High Precision Devices, Inc, Boulder, Colorado) consisting of 13 vials filled with various concentrations of polymer polyvinylpyrrolidone (PVP) in aqueous solution was imaged with a standard Quantitative Imaging Biomarkers Alliance (QIBA) DWI spin echo, echo planar imaging (SE EPI) acquisition. The same phantom was then imaged with a DWI PROPELLER sequence at varying echo train lengths (ETL) of 8, 20, and 32, as well as b‐values of 400, 900, and 2000. QIBA DWI phantom analysis software was used to generate ADC maps and create region of interests (ROIs) for quantitative measurements of each vial. Mean and standard deviations of the ROIs were compared.

Results:

The SE EPI sequence generated ADC values that showed very good agreement with the known ADC values of the phantom (r2 = 0.9995, slope = 1.0061). The ADC values measured from the PROPELLER sequences were inflated, but were highly correlated with an r2 range from 0.8754 to 0.9880. The PROPELLER sequence with an ETL=20 and b‐value of 0 and 2000 showed the closest agreement (r2 = 0.9034, slope = 0.9880).

Conclusion:

The DW PROPELLER sequence is promising for quantitative evaluation of ADC values. A drawback of the PROPELLER sequence is the longer acquisition time. The 180° refocusing pulses may also cause the observed increase in ADC values compared to the standard SE EPI DW sequence. However, the FSE sequence offers an advantage with in‐plane motion and geometric distortion which will be investigated in future studies.
TU‐H‐CAMPUS‐IeP2‐03: Development of 3D Printed Coronary Phantoms for In‐Vitro CT‐FFR Validation Using Data from 320‐ Detector Row Coronary CT Angiography
Authors: Ionita C , Angel E , Mitsouras D , Rudin S , Bednarek D , Zaid S , Wilson M , Rybicki F
Published: July 2016

Purpose:

To validate Computed Tomography Fractional Flow Reserve (CT‐FFR) measurements with accurate 3D printed coronary phantoms.

Methods:

DICOM data from four phases in two patients imaged with a standard 320 × 0.5mm coronary CT acquisition (70–80% cardiac cycle) underwent semi‐automated segmentation using a research workstation. Both patients had a >50% stenosis from the clinical image interpretation. Each volume was saved as a Stereo Lithographic (STL) file with 250 micron resolution. The 3D geometries were qualitatively assessed; the best of the four phases was 3D printed using a Stratasys Eden260V printer in Tango+, a rubber‐like material that roughly emulates mechanical properties of human vasculature. We connected the model to a programmable pump and measured the pressure drop using pressure sensors embedded proximal and distal to the arterial stenosis. Next, the STL files used for the 3D printed models were uploaded in the ANSYS meshing tool (ICEM CFD 16.1). A standard meshing process was applied and the meshed geometry was directly imported in the ANSYS Fluent for Computational Flow Dynamics simulations. The CFD simulations were used to calculate the CT‐FFR and compared to the bench top FFR measured in the 3D printed phantoms.

Results:

FFR‐CT measurements and phantoms were completed in within an hour after the segmentation. Patient 1 had a 60% stenosis that resulted in a CT‐FFR of 0.68. The second case had a 50% stenosis and a CT‐FFR of 0.75. The average bench top FFR measurements were 0.72 and 0.80, respectively.

Conclusion:

This pilot investigation demonstrated the use of a bench‐top coronary model for CT‐FFR validation. The measurements and the CFD simulations agreed within 6%. Project supported by Support: Toshiba America Medical Systems Corp.and NIH grant R01‐EB002873.

Project supported by Toshiba America Medical Systems Corp.and partial support from NIH grant R01‐EB002873
TU‐H‐CAMPUS‐JeP2‐01: Inter‐Observer Delineation Comparison of Visible Glandular Breast Tissue On Magnetic Resonance Imaging and Computed Tomography (prone and Supine)
Authors: Pogson EM , Delaney G , Ahern V , Boxer M , David S , Dimigen M , Harvey J , Koh E , Lim K , Papadatos G , Yap M , Batumalai V , Metcalfe P , Holloway L
Published: July 2016

Purpose:

Breast cancers predominantly arise from Glandular Breast Tissue (GBT). If the GBT can be treated effectively post‐operatively utilising radiotherapy this may be adequate volumetric coverage for adjuvant breast radiotherapy. Adequate imaging of the GBT is necessary and will be assessed between MRI and CT modalities. GBT visualisation is acknowledged to be qualitatively superior on Magnetic Resonance Image (MRI) compared to Computed Tomography (CT), the current radiotherapy imaging standard, however this has not been quantitatively assessed. For radiotherapy purposes it is important that any treatment volume can be consistently defined between observers. This study investigates the consistency of CT and MRI GBT contours for potential radiotherapy planning.

Methods:

Ten experts (9 breast radiation oncologists and 1 radiologist) contoured the extent of the visible GBT for 33 patients on MRI and CT (both without contrast), which was performed according to a contouring guideline in supine and prone patient positions. The GBT volume was not a conventional whole breast radiotherapy planning volume, but rather the extent of GBT that was indicated from the CT or MR imaging. Volumes were compared utilizing the dice similarity coefficient (DSC), kappa statistic, and Hausdorff Distances (HDs) to ascertain the modality that was most consistently volumed.

Results:

The inter‐observer concordance was of substantial agreement (kappa above 0.6) for the CT supine, CT prone, MRI supine and MRI prone datasets. The MRI GBT volumes were larger than the CT GBT volumes (p<0.001). Inter‐observer conformity was higher for CT than MRI, although the magnitude of this difference was small (VOI<0.04). Conformity between modalities (CT and MRI) was in agreement for both prone and supine, DSC=0.75. Prone GBT volumes were larger than supine for both MRI and CT.

Conclusion:

MRI improves the extent of GBT delineation. The role of MRI guided, GBT‐targeted radiotherapy requires investigation in a clinical trial.

This work was supported by a grant number APP1033237 from Cancer Australia and the National Breast Cancer Foundation.
TU‐H‐CAMPUS‐JeP2‐02: Interobserver Variability of CT, PET‐CT and MRI Based Primary Tumor Delineation for Lung Cancer
Authors: Karki K , Hugo G , Saraiya S , Jan N , Schuster J , Schutzer M , Fahrner L , Groves R , Ford J , Weiss E
Published: July 2016

Purpose:

Target delineation in lung cancer radiotherapy has, in general, large variability. MRI has so far not been investigated in detail for lung cancer delineation variability. The purpose of this study is to investigate delineation variability for lung tumors using MRI and compare it to CT alone and PET‐CT based delineations.

Methods:

Seven physicians delineated the primary tumor volumes of nine patients for the following scenarios: (1) CT only; (2) post‐contrast T1‐weighted MRI registered with diffusion‐weighted MRI; and (3) PET‐CT fusion images. To compute interobserver variability, the median surface was generated from all observers’ contours and used as the reference surface. A single physician labeled the interface types (tumor to lung, atelectasis (collapsed lung), hilum, mediastinum, or chest‐wall) on the median surface. Volume variation (normalized to PET‐CT volume), minimum distance (MD), and bidirectional local distance (BLD) between individual observers’ contours and the reference contour were measured.

Results:

CT‐ and MRI‐based normalized volumes were 1.61±0.76 (mean±SD) and 1.38±0.44, respectively, both significantly larger than PET‐CT (p<0.05, paired t‐test). The overall uncertainty (root mean square of SD values over all points) of both BLD and MD measures of the observers for the interfaces were not significantly different (p>0.05, two‐samples t‐test) for all imaging modalities except between tumor‐mediastinum and tumor‐atelectasis in PET‐CT. The largest mean overall uncertainty was observed for tumor‐atelectasis interface, the smallest for tumor‐mediastinum and tumor‐lung interfaces for all modalities. The whole tumor uncertainties for both BLD and MD were not significantly different between any two modalities (p>0.05, paired t‐test). Overall uncertainties for the interfaces using BLD were similar to using MD.

Conclusion:

Large volume variations were observed between the three imaging modalities. Contouring variability appeared to depend on the interface type. This study will be useful for understanding the delineation uncertainty for radiotherapy planning of lung cancer using different imaging modalities.

Disclosures: Research agreement with Phillips Healthcare (GH and EW), National Institutes of Health Licensing agreement with Varian Medical Systems (GH and EW), research grants from the National Institute of Health (GH and EW), UpToDate royalties (EW), and none (others). Authors have no potential conflicts of interest to disclose.
TU‐H‐CAMPUS‐TeP2‐04: Measurement of Stereotactic Output Factors with DNA Double‐Strand Breaks
Authors: Cline K , Obeidat M , Stathakis S , Kabat C , Markovic M , Papanikolaou N , Rasmussen K , Gutierrez A , Ha C , Lee S , Shim E , Kirby N
Published: July 2016

Purpose:

Radiotherapy treatment is specified by radiation dose prescriptions, but biological DNA damage actually controls treatment effectiveness. It is impractical to directly measure dose in the clinic, so we measure quantities, such as collected charge, and calculate the relationship to dose. At small fields, such as those in stereotactic radiosurgery (SRS), charged‐particle equilibrium (CPE) breaks down and the accuracy of the measurement for delivered dose decreases. By measuring DNA double‐strand breaks (DSB) directly, we believe treatment accuracy could improve by providing a more meaningful measurement.

Methods:

A DNA dosimeter, consisting of magnetic streptavidin beads attached to 4 kilobase pair DNA strands labeled with biotin and fluorescein amidite (FAM) on opposing ends, was suspended in phosphate‐buffered saline (PBS). Twenty µL samples were placed in plastic micro‐capillary tubes inside a water tank setup and irradiated with 10 cm, 3 cm, 1.25 cm, 0.75 cm, and 0.5 cm radiation field sizes, where the three smallest sizes were cones. After irradiation, the dosimeters were mechanically separated into beads (intact DNA) and supernatant (broken DNA/FAM) using a magnet. The fluorescence was read and the probability of DSB was calculated. This was used to calculate the output factor for an SRS beam and compared to that measured using a diode detector.

Results:

The output factors relative to a 10 cm field were 0.89±0.07, 0.76±0.08, 0.59±0.04, and 0.78±0.12 for the field sizes of 3 cm, 1.25 cm, 0.75 cm, and 0.5 cm, respectively. Some of the diode measurements do not fall within these uncertainties.

Conclusion:

This was the first attempt to measure output factors in a water tank with the DNA dosimeter. Although differences compared to the diode were observed, the uncertainty analysis ignored systematic errors. For future work, we will repeat this experiment to quantify and correct systematic errors, such as those caused by positional alignment and sample contamination.

This work was funded in part by CPRIT (RP140105).
TU‐H‐CAMPUS‐JeP3‐05: Adaptive Determination of Needle Sequence HDR Prostate Brachytherapy with Divergent Needle‐By‐Needle Delivery
Authors: Borot de Battisti M , Denis de Senneville B , Maenhout M , Hautvast G , Binnekamp D , Lagendijk J J W , Van Vulpen M , Moerland M A
Published: July 2016

Purpose:

To develop a new method which adaptively determines the optimal needle insertion sequence for HDR prostate brachytherapy involving divergent needle‐by‐needle dose delivery by e.g. a robotic device. A needle insertion sequence is calculated at the beginning of the intervention and updated after each needle insertion with feedback on needle positioning errors.

Methods:

Needle positioning errors and anatomy changes may occur during HDR brachytherapy which can lead to errors in the delivered dose. A novel strategy was developed to calculate and update the needle sequence and the dose plan after each needle insertion with feedback on needle positioning errors. The dose plan optimization was performed by numerical simulations. The proposed needle sequence determination optimizes the final dose distribution based on the dose coverage impact of each needle. This impact is predicted stochastically by needle insertion simulations. HDR procedures were simulated with varying number of needle insertions (4 to 12) using 11 patient MR data‐sets with PTV, prostate, urethra, bladder and rectum delineated. Needle positioning errors were modeled by random normally distributed angulation errors (standard deviation of 3 mm at the needle's tip). The final dose parameters were compared in the situations where the needle with the largest vs. the smallest dose coverage impact was selected at each insertion.

Results:

Over all scenarios, the percentage of clinically acceptable final dose distribution improved when the needle selected had the largest dose coverage impact (91%) compared to the smallest (88%). The differences were larger for few (4 to 6) needle insertions (maximum difference scenario: 79% vs. 60%). The computation time of the needle sequence optimization was below 60s.

Conclusion:

A new adaptive needle sequence determination for HDR prostate brachytherapy was developed. Coupled to adaptive planning, the selection of the needle with the largest dose coverage impact increases chances of reaching the clinical constraints.

M. Borot de Battisti is funded by Philips Medical Systems Nederland B.V.; M. Moerland is principal investigator on a contract funded by Philips Medical Systems Nederland B.V.; G. Hautvast and D. Binnekamp are fulltime employees of Philips Medical Systems Nederland B.V.