bluuebunny/crossref_metadata_2025 huggingface dataset:
MO‐FG‐201‐01: High‐Impact Presentations
Authors: Weiker H.
Published: June 2015

Oral presentations are one of the most important tools to advance education, scientific research, and clinical excellence in medical physics. Medical physicists do not often captivate their audiences like a Steve Jobs keynote or a TED talk, but every physicist can learn to engage their audiences and deliver their message in a memorable way using their own personality and style. This interactive session will teach attendees to discover their own style and voice and to use it to engage and connect with their audiences. Audience reception and response will be reviewed in terms of the speaker's executive presence and content, as well as research on the psychology of audiences and physiology of speakers. Physicists will learn how to organize and mentally prepare themselves as well as their PowerPoint slides.

Learning Objectives:

Develop executive presence: poised under pressure to deliver a message in a relaxed, casual, and credible way

Connect with an audience by creating harmony between the content and the visual and audible elements of a presentation

Confidently deliver engaging presentations in the individual's voice and personality

Heidi Weiker and Tanya Weiker are co‐owners of Spherica LLC.
MO‐F‐CAMPUS‐T‐03: Data Driven Approaches for Determination of Treatment Table Tolerance Values for Record and Verification Systems
Authors: Gupta N , DiCostanzo D , Fullenkamp M
Published: June 2015

Purpose:

To determine appropriate couch tolerance values for modern radiotherapy linac R&V systems with indexed patient setup.

Methods:

Treatment table tolerance values have been the most difficult to lower, due to many factors including variations in patient positioning and differences in table tops between machines. We recently installed nine linacs with similar tables and started indexing every patient in our clinic. In this study we queried our R&V database and analyzed the deviation of couch position values from the acquired values at verification simulation for all patients treated with indexed positioning. Mean and standard deviations of daily setup deviations were computed in the longitudinal, lateral and vertical direction for 343 patient plans. The mean, median and standard error of the standard deviations across the whole patient population and for some disease sites were computed to determine tolerance values.

Results:

The plot of our couch deviation values showed a gaussian distribution, with some small deviations, corresponding to setup uncertainties on non‐imaging days, and SRS/SRT/SBRT patients, as well as some large deviations which were spot checked and found to be corresponding to indexing errors that were overriden. Setting our tolerance values based on the median + 1 standard error resulted in tolerance values of 1cm lateral and longitudinal, and 0.5 cm vertical for all non‐ SRS/SRT/SBRT cases. Re‐analizing the data, we found that about 92% of the treated fractions would be within these tolerance values (ignoring the mis‐indexed patients). We also analyzed data for disease site based subpopulations and found no difference in the tolerance values that needed to be used.

Conclusion:

With the use of automation, auto‐setup and other workflow efficiency tools being introduced into radiotherapy workflow, it is very essential to set table tolerances that allow safe treatments, but flag setup errors that need to be reassessed before treatments.
MO‐F‐CAMPUS‐T‐05: SQL Database Queries to Determine Treatment Planning Resource Usage
Authors: Fox C , Gladstone D
Published: June 2015

Purpose:

A radiation oncology clinic's treatment capacity is traditionally thought to be limited by the number of machines in the clinic. As the number of fractions per course decrease and the number of adaptive plans increase, the question of how many treatment plans a clinic can plan becomes increasingly important. This work seeks to lay the ground work for assessing treatment planning resource usage.

Methods:

Care path templates were created using the Aria 11 care path interface. Care path tasks included key steps in the treatment planning process from the completion of CT simulation through the first radiation treatment. SQL Server Management Studio was used to run SQL queries to extract task completion time stamps along with care path template information and diagnosis codes from the Aria database. 6 months of planning cycles were evaluated. Elapsed time was evaluated in terms of work hours within Monday – Friday, 7am to 5pm.

Results:

For the 195 validated treatment planning cycles, the average time for planning and MD review was 22.8 hours. Of those cases 33 were categorized as urgent. The average planning time for urgent plans was 5 hours. A strong correlation between diagnosis code and range of elapsed planning time was as well as between elapsed time and select diagnosis codes was observed. It was also observed that tasks were more likely to be completed on the date due than the time that they were due. Follow‐up confirmed that most users did not look at the due time.

Conclusion:

Evaluation of elapsed planning time and other tasks suggest that care paths should be adjusted to allow for different contouring and planning times for certain diagnosis codes and urgent cases. Additional clinic training around task due times vs dates or a structuring of care paths around due dates is also needed.
MO‐F‐CAMPUS‐J‐01: Effect of Iodine Contrast Agent Concentration On Cerebrovascular Dose for Synchrotron Radiation Microangiography Based On a Simple Mouse Head Model and a Voxel Mouse Head Phantom
Authors: Lin H , Jing J , Lu Y , Xie C
Published: June 2015

Purpose:

To find effective setting methods to mitigate the irradiation injure in synchrotron radiation microangiography(SRA) by Monte Carlo simulation.

Methods:

A mouse 1‐D head model and a segmented voxel mouse head phantom were simulated by EGSnrc/Dosxyznrc code to investigate the dose enhancement effect of the iodine contrast agent irradiated by a monochromatic synchrotron radiation(SR) source. The influence of, like iodine concentration (IC), vessel width and depth, with and without skull layer protection and the various incident X ray energies, were simulated. The dose enhancement effect and the absolute dose based on the segmented voxel mouse head phantom were evaluated.

Results:

The dose enhancement ratio depends little on the irradiation depth, but strongly on the IC, which is linearly increases with IC. The skull layer protection cannot be ignored in SRA, the 700µm thick skull could decrease 10% of the dose. The incident X‐ray energy can significantly affact the dose. E.g. compared to the dose of 33.2keV for 50mgI/ml, the 32.7keV dose decreases 38%, whereas the dose of 33.7 keV increases 69.2%, and the variation will strengthen more with enhanced IC. The segmented voxel mouse head phantom also showed that the average dose enhancement effect and the maximal voxel dose per photon depends little on the iodine voxel volume ratio, but strongly on IC.

Conclusion:

To decrease dose damage in SRA, the high‐Z contrast agent should be used as little as possible, and try to avoid radiating locally the injected position immediately after the contrast agent injection. The fragile vessel containing iodine should avoid closely irradiating. Avoiding irradiating through the no or thin skull region, or appending thin equivalent material from outside to protect is also a better method. As long as SRA image quality is ensured, using incident X‐ray energy as low as possible.
MO‐F‐CAMPUS‐J‐02: Human Implanted Micro Bio Chip for Real‐Time Atrial Fibrillation Monitoring with Wireless Power Transmission
Authors: Lee J
Published: June 2015

Purpose:

There are numerous medical problems whose treatment requires the constant monitoring of vital signs from several body organs. In this study, a micro‐sized implantable electrocardiogram (ECG) sensor for personal heart disease monitoring was developed, as such devices generally provide a high diagnostic yield.

Methods:

An op‐amp amplifies an input electrical potential to the level desired by the user and produces an output potential augmented to this intended level. For this study an instrumentation amplifier was fabricated using op‐amps and configured to amplify micro‐fine ECG signals by a factor of about 100 using a band‐pass filter (BPF). The proposed ECG sensor has a current consumption of about 11 mA and a noise generation inversely proportional to the length of the wireless communication antenna inside the sensor. The packaging materials selected must be biocompatible to avoid causing inflammation or necrosis of human tissues. In addition, a near‐field wireless power transmission system and the medical Implant Communication Service (MICS) was used as a communications and power protocol. MICS operates in the frequency range of 402–405 MHz and is normally used for communication between body‐worn monitoring systems and implants.

Results:

A pig was used as a sensor‐implanted animal model because the animal's physiological characteristics are similar to those of humans. An incision was made between the left 5th–7th ribs and separated using blunt dissection to a depth of 4 mm under the skin. From the experiments, we successfully monitor the ECG with wireless communication and wireless power transmission.

Conclusion:

This study demonstrated that the use of a quasi‐permanent

ECG employing a double loop coil‐shaped magnetic resonance‐type wireless power transmission system sensor eliminates the need for surgical replacement.
MO‐F‐CAMPUS‐I‐02: Accuracy in Converting the Average Breast Dose Into the Mean Glandular Dose (MGD) Using the F‐Factor in Cone Beam Breast CT‐ a Monte Carlo Study Using Homogeneous and Quasi‐Homogeneous Phantoms
Authors: Lai C , Zhong Y , Wang T , Shaw C
Published: June 2015

Purpose:

To investigate the accuracy in estimating the mean glandular dose (MGD) for homogeneous breast phantoms by converting from the average breast dose using the F‐factor in cone beam breast CT.

Methods:

EGSnrc‐based Monte Carlo codes were used to estimate the MGDs. 13‐cm in diameter, 10‐cm high hemi‐ellipsoids were used to simulate pendant‐geometry breasts. Two different types of hemi‐ellipsoidal models were employed: voxels in quasi‐homogeneous phantoms were designed as either adipose or glandular tissue while voxels in homogeneous phantoms were designed as the mixture of adipose and glandular tissues. Breast compositions of 25% and 50% volume glandular fractions (VGFs), defined as the ratio of glandular tissue voxels to entire breast voxels in the quasi‐homogeneous phantoms, were studied. These VGFs were converted into glandular fractions by weight and used to construct the corresponding homogeneous phantoms. 80 kVp x‐rays with a mean energy of 47 keV was used in the simulation. A total of 109 photons were used to image the phantoms and the energies deposited in the phantom voxels were tallied. Breast doses in homogeneous phantoms were averaged over all voxels and then used to calculate the MGDs using the F‐factors evaluated at the mean energy of the x‐rays. The MGDs for quasi‐homogeneous phantoms were computed directly by averaging the doses over all glandular tissue voxels. The MGDs estimated for the two types of phantoms were normalized to the free‐in‐air dose at the iso‐center and compared.

Results:

The normalized MGDs were 0.756 and 0.732 mGy/mGy for the 25% and 50% VGF homogeneous breasts and 0.761 and 0.733 mGy/mGy for the corresponding quasi‐homogeneous breasts, respectively. The MGDs estimated for the two types of phantoms were similar within 1% in this study.

Conclusion:

MGDs for homogeneous breast models may be adequately estimated by converting from the average breast dose using the F‐factor.
MO‐F‐CAMPUS‐J‐02: Commissioning of Radiofrequency Tracking for Gated SBRT of the Liver Using Novel Motion System
Authors: James J , Cetnar A , Nguyen V , Wang B
Published: June 2015

Purpose:

Tracking soft tissue targets has recently been approved as a new application of the Calypso radiofrequency tracking system allowing for gated treatment of the liver based on the motion of the target volume itself. As part of the commissioning process, an end‐to‐end test was performed using a 3D diode array and 6D motion platform to verify the dosimetric accuracy and establish the workflow of gated SBRT treatment of the liver using Calypso.

Methods:

A 4DCT scan of the ScandiDos Delta4 phantom was acquired using the HexaMotion motion platform to simulate realistic breathing motion. A VMAT plan was optimized on the end of inspiration phase of the 4DCT scan and delivered to the Delta4 phantom using the Varian TrueBeam. The treatment beam was gated by Calypso to deliver dose at the end of inspiration. The expected dose was compared to the delivered dose using gamma analysis. In addition, gating limits were investigated to determine how large the gating range can be while still maintaining dosimetric accuracy.

Results:

The 3%/3mm and 2%/2mm gamma pass rate for the gated treatment delivery was 100% and 98.4%, respectively. When increasing the gating limits beyond the known extent of planned motion from the 4DCT, the gamma pass rates decreased as expected. The 3%/3mm gamma pass rate for a 1, 2, and 3mm increase in gating limits were measured to be 96.0%, 92.7%, and 78.8%, respectively.

Conclusion:

Radiofrequency tracking was shown to be an effective way to provide gated SBRT treatment of the liver. Baseline gating limits should be determined by measuring the extent of target motion during the respiratory phases used for planning. We recommend adding 1mm to the baseline limits to provide the proper balance between treatment efficiency and dosimetric accuracy.
MO‐F‐CAMPUS‐J‐03: Development of a Human Brain PET for On‐Line Proton Beam‐Range Verification
Authors: Shao Yiping
Published: June 2015

Purpose:

To develop a prototype PET for verifying proton beam‐range before each fractionated therapy that will enable on‐line re‐planning proton therapy.

Methods:

Latest “edge‐less” silicon photomultiplier arrays and customized ASIC readout electronics were used to develop PET detectors with depth‐of‐interaction (DOI) measurement capability. Each detector consists of one LYSO array with each end coupled to a SiPM array. Multiple detectors can be seamlessly tiled together to form a large detector panel. Detectors with 1.5×1.5 and 2.0×2.0 mm crystals at 20 or 30 mm lengths were studied. Readout of individual SiPM or signal multiplexing was used to transfer 3D interaction position‐coded analog signals through flexible‐print‐circuit cables or PCB board to dedicated ASIC front‐end electronics to output digital timing pulses that encode interaction information. These digital pulses can be transferred to, through standard LVDS cables, and decoded by a FPGA‐based data acquisition of coincidence events and data transfer. The modular detector and scalable electronics/data acquisition will enable flexible PET system configuration for different imaging geometry.

Results:

Initial detector performance measurement shows excellent crystal identification even with 30 mm long crystals, ∼18% and 2.8 ns energy and timing resolutions, and around 2–3 mm DOI resolution. A small prototype PET scanner with one detector ring has been built and evaluated, validating the technology and design. A large size detector panel has been fabricated by scaling up from modular detectors. Different designs of resistor and capacitor based signal multiplexing boards were tested and selected based on optimal crystal identification and timing performance. Stackable readout electronics boards and FPGA‐based data acquisition boards were developed and tested. A brain PET is under construction.

Conclusion:

Technology of large‐size DOI detector based on SiPM array and advanced readout has been developed. PET imaging performance and initial phantom studies of on‐line proton beam‐range measurement will be conducted and reported.

NIH grant R21CA187717; Cancer Prevention and Research Institute of Texas grant RP120326
MO‐F‐CAMPUS‐I‐01: A System for Automatically Calculating Organ and Effective Dose for Fluoroscopically‐Guided Procedures
Authors: Xiong Z , Vijayan S , Rana V , Rudin S , Bednarek D
Published: June 2015

Purpose:

A system was developed that automatically calculates the organ and effective dose for individual fluoroscopically‐guided procedures using a log of the clinical exposure parameters.

Methods:

We have previously developed a dose tracking system (DTS) to provide a real‐time color‐coded 3D‐ mapping of skin dose. This software produces a log file of all geometry and exposure parameters for every x‐ray pulse during a procedure. The data in the log files is input into PCXMC, a Monte Carlo program that calculates organ and effective dose for projections and exposure parameters set by the user. We developed a MATLAB program to read data from the log files produced by the DTS and to automatically generate the definition files in the format used by PCXMC. The processing is done at the end of a procedure after all exposures are completed. Since there are thousands of exposure pulses with various parameters for fluoroscopy, DA and DSA and at various projections, the data for exposures with similar parameters is grouped prior to entry into PCXMC to reduce the number of Monte Carlo calculations that need to be performed.

Results:

The software developed automatically transfers data from the DTS log file to PCXMC and runs the program for each grouping of exposure pulses. When the dose from all exposure events are calculated, the doses for each organ and all effective doses are summed to obtain procedure totals. For a complicated interventional procedure, the calculations can be completed on a PC without manual intervention in less than 30 minutes depending on the level of data grouping.

Conclusion:

This system allows organ dose to be calculated for individual procedures for every patient without tedious calculations or data entry so that estimates of stochastic risk can be obtained in addition to the deterministic risk estimate provided by the DTS.

Partial support from NIH grant R01EB002873 and Toshiba Medical Systems Corp.
MO‐F‐CAMPUS‐I‐04: Patient Eye‐Lens Dose Reduction in Routine Brain CT Examinations Using Organ‐Based Tube Current Modulation and In‐Plane Bismuth Shielding
Authors: Tsai Hui‐Yu , Liao Ying‐Lan , Lai Nan‐Ku , Chen Jun‐Rong , Chen Tou‐Rong
Published: June 2015

Purpose:

The purpose of this study is to assess eye‐lens dose for patients who underwent brain CT examinations using two dose reduction

Methods:

organ‐based tube current modulation (OBTCM) and in‐plane bismuth shielding method.

Methods:

This study received institutional review board approval; written informed consent to participate was obtained from all patients. Ninety patients who underwent the routine brain CT examination were randomly assigned to three groups, ie. routine, OBTCM, and bismuth shield. The OBTCM technique reduced the tube current when the X‐ray tube rotates in front of patients’ eye‐lens region. The patients in the bismuth shield group were covered one‐ply bismuth shield in the eyes’ region. Eye‐lens doses were measured using TLD‐100H chips and the total effective doses were calculated using CT‐Expo according to the CT scanning parameters. The surface doses for patients at off‐center positions were assessed to evaluate the off‐centering effect.

Results:

Phantom measurements indicates that OBTCM technique could reduced by 26% to 28% of the surface dose to the eye lens, and increased by 25% of the surface dose at the opposed incident direction at the angle of 180°. Patients’ eye‐lens doses were reduced 16.9% and 30.5% dose of bismuth shield scan and OBTCM scan, respectively compared to the routine scan. The eye‐lens doses were apparently increased when the table position was lower than isocenter.

Conclusion:

Reducing the dose to the radiosensitive organs, such as eye lens, during routine brain CT examinations could lower the radiation risks. The OBTCM technique and in‐plane bismuth shielding could be used to reduce the eye‐lens dose. The eye‐lens dose could be effectively reduced using OBTCM scan without interfering the diagnostic image quality. Patient position relative the CT gantry also affects the dose level of the eye lens.

This study was supported by the grants from the Ministry of Science and Technology of Taiwan (MOST103‐2314‐B‐182‐009‐MY2), and Chang Gung Memorial Hospital (CMRPD1C0682).
MO‐F‐CAMPUS‐I‐05: Radiation Dosimetry of 99mTc‐IDA‐D‐[c(RGDfK)]2, a SPECT Agent for Angiogenesis Imaging
Authors: Kim J
Published: June 2015

Purpose:

Tc‐99m labeled IDA‐D‐[c(RGDfK)2 ( 99mTc‐RGD) is a recently developed radiotracer for gamma camera or single photon emission computed tomography (SPECT) imaging and promising agent for the visualization of angiogenesis. In this study, we investigated the internal radiation dosimetry of 99mTc‐RGD in humans.

Methods:

Six normal controls (F:M=4:2; 68.3±3.2 years; 56.5±10.7 kg) were participated in this study. Simultaneous anterior and posterior scans of whole‐body were performed using dual head gamma camera system. Before the emission scan, transmission scan was performed just before injection of 99mTc‐RGD using Co‐57 flood source. After an intravenous injection of 388.7±29.3 MBq of 99mTc‐RGD, six serial emission scans were performed at 0, 1, 2, 4, 8 and 24 hours post‐injection. The anterior and posterior images were geometrically averaged and attenuation correction was applied using transmission scan image. Regions of interest (ROIs) were drawn on liver, gallbladder, kidneys, urinary bladder, spleen, brain, and large intestine. Time activity curves were obtained from serial emission scan and ROIs. The number of disintegrations per unit activity administered (residence time) were calculated from the area under the curve of time activity curves and injected dose of each patient. Finally, the radiation dose for each organ and effective doses were obtained using OLINDA/EXM 1.1 software and residence time.

Results:

High radiation doses were reported on renal and biliary excretion tracks such as urinary bladder wall, upper large intestine, kidneys, liver and gallbladder wall and their doses were 19.15±6.84, 19.28±4.78, 15.67±0.90, 9.13±1.71 and 9.09±2.03 µGy/MBq, respectively. The effective dose and effective dose equivalent were 5.08±0.53 and 7.11±0.58 µSv/MBq, respectively.

Conclusion:

We evaluated the radiation dose of 99mTc‐RGD, which has an acceptable effective radiation dose compare to the other Tc‐99m labeled radio‐tracers.
TU‐CD‐213‐03: Communication, Negotiation, and Persuasion: Approaches for Better Results
Authors: Wells M.
Published: June 2015

As part of the AAPM's Scope of Practice, medical physicists are expected to collaborate effectively with practioners and allied health care providers. Interpersonal skills such as communication, negotiation and persuasion are vital for successful collaboration to achieve shared goals. This session will provide some theoretical background of these interpersonal skills as well as specific techniques and practical tools to influence others. Applications of these interpersonal skills for administrative and human resource management purposes vital to medical physicists will be shared. Session attendees will gain knowledge and tools to help them effectively collaborate with administrative and physician leaders in areas such as capital and human resource selection, prioritization, and implementation. Participants will hear methods of how to articulate their goals and to understand the goals of administration, helping ensure alignment of purpose.

Session speakers will present one of the topics: equipment selection, budget creation, contracts, and program‐related policy development. Specifics may include designing a business case in language that administrators understand, calculating the prioritization of budget requests, and influencing policies for safe and effective care. Human resource topics may include staffing justification, recruitment for fit, employment contracts, and benefits. Speakers will provide examples in both radiation therapy and diagnostic imaging departments and will share experiences and outcomes of their approaches for better results.

Learning Objectives:

After this course attendees will be better able to

Understand the shared goal between administrative and physicist leadership.

Articulate the “why” of the technical or human resource need.

Utilize communication, negotiation and persuasion tools to improve collaboration.
TU‐CD‐213‐04: Panel Discussion
Authors: Johnson J.
Published: June 2015

As part of the AAPM's Scope of Practice, medical physicists are expected to collaborate effectively with practioners and allied health care providers. Interpersonal skills such as communication, negotiation and persuasion are vital for successful collaboration to achieve shared goals. This session will provide some theoretical background of these interpersonal skills as well as specific techniques and practical tools to influence others. Applications of these interpersonal skills for administrative and human resource management purposes vital to medical physicists will be shared. Session attendees will gain knowledge and tools to help them effectively collaborate with administrative and physician leaders in areas such as capital and human resource selection, prioritization, and implementation. Participants will hear methods of how to articulate their goals and to understand the goals of administration, helping ensure alignment of purpose.

Session speakers will present one of the topics: equipment selection, budget creation, contracts, and program‐related policy development. Specifics may include designing a business case in language that administrators understand, calculating the prioritization of budget requests, and influencing policies for safe and effective care. Human resource topics may include staffing justification, recruitment for fit, employment contracts, and benefits. Speakers will provide examples in both radiation therapy and diagnostic imaging departments and will share experiences and outcomes of their approaches for better results.

Learning Objectives:

After this course attendees will be better able to

Understand the shared goal between administrative and physicist leadership.

Articulate the “why” of the technical or human resource need.

Utilize communication, negotiation and persuasion tools to improve collaboration.
TU‐CD‐304‐07: Intensity Modulated Electron Beam Therapy Employing Small Fields in Virtual Scanning Mode
Authors: Rodrigues A , Liang B , Yin F , Wu Q
Published: June 2015

Purpose:

Dynamic electron radiation therapies such as dynamic electron arc radiotherapy (DEAR) utilize small fields to provide target conformity and fluence modulation. The purpose of this study is to demonstrate the feasibility of virtual scanning mode using small fields.

Methods:

Monte Carlo simulations (EGSnrc/BEAMnrc/DOSXYZnrc) were performed using validated Varian TrueBeam phase space files for electron beam energies of 6, 9, 12, and 16 MeV and square/circular fields (1×1/1, 2×2/2, 3×3/3, 4×4/4, 5×5/5 cm2/cm diameter). Resulting dose distributions (kernels) were used for subsequent calculations. The following analyses were performed: (1) Comparison of composite square fields and reference 10×10 cm2 dose distributions and (2) Scanning beam deliveries for square and circular fields realized as the convolution of kernels and scanning pattern. Preliminary beam weight and pattern optimization were also performed. Two linear scans of 10 cm with/without overlap were modeled. Comparison metrics included depth and orthogonal profiles at dmax.

Results:

(1) Composite fields regained reference depth dose profiles for most energies and fields within 5%. Smaller kernels and higher energies increased dose in the build‐up and Bremsstrahlung region (30%, 16MeV and 1×1 cm2), while reference dmax was maintained for all energies and composite fields. Smaller kernels (<2×2 cm2) maintained penumbra and field size within 0.2 cm, and flatness within 2%. Deterioration of penumbra for larger kernels (5×5 cm2) were observed. Balancing desirable dosimetry and efficiencies suggests that smaller kernels are used at edges and larger kernels in the center of the target. (2) Beam weight optimization improved cross‐plane penumbra (0.2 cm) and increased the field size (0.4 cm) on average. In‐plane penumbra and field size remained unchanged. Overlap depended on kernel size and optimal overlap resulted in flatness ±2%.

Conclusion:

Dynamic electron beam therapy in virtual scanning mode is feasible by employing small fields to achieve desired dose distributions and acceptable efficiencies.
TU‐CD‐304‐08: Feasibility of a VMAT‐Based Spatially Fractionated Grid Therapy Technique
Authors: Zhao B , Jin J , Liu M , Huang Y , Kim J , Brown S , Siddiqui F , Chetty I , Wen N
Published: June 2015

Purpose:

Grid therapy (GT) uses spatially modulated radiation doses to treat large tumors without significant toxicities. Incorporating 3D conformal‐RT or IMRT improved single‐field GT by reducing dose to normal tissues spatially through the use of multiple fields. The feasibility of a MLC‐based, inverse‐planned multi‐field GT technique has been demonstrated. Volumetric modulated arc therapy (VMAT) provides conformal dose distributions with the additional potential advantage of reduced treatment times. In this study, we characterize a new VMAT‐based GT (VMAT‐GT) technique with respect to its deliverability and dosimetric accuracy.

Methods:

A lattice of 5mm‐diameter spheres was created as the boost volume within a large treatment target. A simultaneous boost VMAT (RapidArc) plan with 8Gy to the target and 20Gy to the boost volume was generated using the Eclipse treatment planning system (AAA‐v11). The linac utilized HD120 MLC and 6MV flattening‐filter free beam. Four non‐coplanar arcs, with couch angles at 0, 45, 90 and 317° were used. Collimator angles were at 45 and 315°. The plan was mapped to a phantom. Calibrated Gafchromic EBT3 films were used to measure the delivered dose.

Results:

The VMAT plan generated a highly spatially modulated dose distribution in the target. D95%, D50%, D5% for the spheres and the targets in Gy were 18.9, 20.6, 23 and 8.0, 9.6, 14.8, respectively. D50% for a 1cm ring 1cm outside the target was 3.0Gy. The peak‐to‐valley ratio of this technique is comparable to previously proposed techniques, but the MUs were reduced by almost 50%. Film dosimetry showed good agreement between calculated and delivered dose, with an overall gamma passing rate of >98% (3% and 1mm). The point dose differences at sphere centers varied from 2–8%.

Conclusion:

The deliverability and dose calculation accuracy of the proposed VMAT‐GT technique demonstrates that ablative radiation doses are deliverable to large tumors safely and efficiently.
TU‐CD‐304‐09: Feasibility Study for Thermoplastic Mask Set Up Monitoring Using Force Sensing Resistor (FSR) Sensor
Authors: Kim T , Kim S , Cho M , Kang S , Kim D , Kim K , Shin D , Suh T
Published: June 2015

Purpose:

To improve the setup accuracy of thermoplastic mask, we developed a new monitoring method based on force sensing technology and evaluated its feasibility.

Methods:

The thermoplastic mask setup monitoring system consists of a force sensing resistor sensor unit, a signal transport device, a control PC and an in‐house software. The system is designed to monitor pressure variation between the mask and patient in real time. It also provides a warning to the user when there is a possibility of movement. A preliminary study was performed to evaluate the reliability of the sensor unit and developed monitoring system with a head phantom. Then, a simulation study with volunteers was conducted to evaluate the feasibility of the monitoring system. Note that the sensor unit can have multiple end‐sensors and every end‐sensor was confirmed to be within 2% reliability in pressure reading through a screening test.

Results:

To evaluate the reproducibility of the proposed monitoring system in practice, we simulated a mask setup with the head phantom. FRS sensors were attached on the face of the head phantom and pressure was monitored. For 3 repeated mask setups on the phantom, the variation of the pressure was less than 3% (only 1% larger than 2% potential uncertainty confirmed in the screening test). In the volunteer study, we intended to verify that the system could detect patient movements within the mask. Thus, volunteers were asked to turn their head or lift their chin. The system was able to detect movements effectively, confirming the clinical feasibility of the monitoring system developed.

Conclusion:

Through the proposed setup monitoring method, it is possible to monitor patient motion inside a mask in real time, which has never been possible with most commonly used systems using non‐radiographic technology such as infrared camera system and surface imaging system.

This work was supported by the Radiation Technology R&D program (No. 2013M2A2A7043498) and the Mid‐career Researcher Program (2014R1A2A1A10050270) through the National Research Foundation of Korea funded by the Ministry of Science, ICT&Future Planning.
TU‐CD‐304‐10: Development and Optimization of “Compton Lens” Collimator Design for Increased Dose Rate in SRS
Authors: Shepard A , Bender E
Published: June 2015

Purpose:

To provide a proof of concept for a new collimator design to increase the dose rate at isocenter for stereotactic radiosurgery (SRS) treatments by taking advantage of off axis Compton scattered photons which are attenuated in current collimators.

Methods:

A fundamentally new collimator design was developed and optimized by introducing a series of slits to a standard block collimator. The introduction of slits allowed for initially off axis radiation that was scattered in the direction of the target to contribute to the target dose. For optimization, the design was broken into two parts: an upper interaction plate where primary scattering occurs, and a lower “Compton slit” region which allows for scattered photons traveling toward the target to reach isocenter. To optimize the design, a series of simulations were performed using MCNP6 in which several key parameters were adjusted and the output was compared to a standard collimator. Key parameters modified included the collimator material, cone size, and interaction plate thickness. The effects of using energies different than the traditional 6 MV beam were also explored.

Results:

An optimized collimator design utilizing a solid interaction plate with a Cesium‐137 beam and a 4 mm cone size resulted in a dose rate increase on the order of 5% relative to standard collimators in use. Currently, designs incorporating a Cesium‐137 source are the most feasible due to necessary size and weight concerns for 6 MV beams.

Conclusion:

Preliminary designs provide a proof of concept and indicate a potential to improve upon the dose rate of current collimators while not largely compromising the sharp dose falloff inherent to SRS. Further optimization into the geometry and positioning of the interaction plate, as well as slit optimization, will likely lead to further dose rate increases than were observed in this study.

Funding for this work was provided by the Wisconsin Alumni Research Foundation (WARF). Authors have a conflict of interest as the technology discussed is patent pending, and thus there is a financial interest in the work.
TU‐CD‐304‐11: Veritas 2.0: A Cloud‐Based Tool to Facilitate Research and Innovation
Authors: Mishra P , Lewis J , Patankar A , Etmektzoglou A , Svatos M
Published: June 2015

Purpose:

We introduce Veritas 2.0, a cloud‐based, non‐clinical research portal, to facilitate translation of radiotherapy research ideas to new delivery techniques. The ecosystem of research tools includes web apps for a research beam builder for TrueBeam Developer Mode, an image reader for compressed and uncompressed XIM files, and a trajectory log file based QA/beam delivery analyzer.

Methods:

The research beam builder can generate TrueBeam readable XML file either from scratch or from pre‐existing DICOM‐RT plans. DICOM‐RT plan is first converted to XML format and then researcher can interactively modify or add control points to them. Delivered beam can be verified via reading generated images and analyzing trajectory log files. Image reader can read both uncompressed and HND‐compressed XIM images. The trajectory log analyzer lets researchers plot expected vs. actual values and deviations among 30 mechanical axes. The analyzer gives an animated view of MLC patterns for the beam delivery. Veritas 2.0 is freely available and its advantages versus standalone software are i) No software installation or maintenance needed, ii) easy accessibility across all devices iii) seamless upgrades and iv) OS independence. Veritas is written using open‐source tools like twitter bootstrap, jQuery, flask, and Python‐based modules.

Results:

In the first experiment, an anonymized 7‐beam DICOM‐RT IMRT plan was converted to XML beam containing 1400 control points. kV and MV imaging points were inserted into this XML beam. In another experiment, a binary log file was analyzed to compare actual vs expected values and deviations among axes.

Conclusions:

Veritas 2.0 is a public cloud‐based web app that hosts a pool of research tools for facilitating research from conceptualization to verification. It is aimed at providing a platform for facilitating research and collaboration.

I am full time employee at Varian Medical systems, Palo Alto.
TU‐CD‐BRD‐01: Making Incident Learning Practical and Useful: Challenges and Previous Experiences
Authors: Ezzell G.
Published: June 2015

It has long been standard practice in radiation oncology to report internally when a patient's treatment has not gone as planned and to report events to regulatory agencies when legally required. Most potential errors are caught early and never affect the patient. Quality assurance steps routinely prevent errors from reaching the patient, and these “near misses” are much more frequent than treatment errors. A growing number of radiation oncology facilities have implemented incident learning systems to report and analyze both errors and near misses. Using the term “incident learning” instead of “event reporting” emphasizes the need to use these experiences to change the practice and make future errors less likely and promote an educational, non‐punitive environment.

There are challenges in making such a system practical and effective. Speakers from institutions of different sizes and practice environments will share their experiences on how to make such a system work and what benefits their clinics have accrued. Questions that will be addressed include:

How to create a system that is easy for front line staff to access

How to motivate staff to report

How to promote the system as positive and educational and not punitive or demeaning

How to organize the team for reviewing and responding to reports

How to prioritize which reports to discuss in depth

How not to dismiss the rest

How to identify underlying causes

How to design corrective actions and implement change

How to develop useful statistics and analysis tools

How to coordinate a departmental system with a larger risk management system

How to do this without a dedicated quality manager

Some speakers’ experience is with in‐house systems and some will share experience with the AAPM/ASTRO national Radiation Oncology Incident Learning System (RO‐ILS). Reports intended to be of value nationally need to be comprehensible to outsiders; examples of useful reports will be shown.

There will be ample time set aside for audience members to contribute to the discussion.

Learning Objectives:

Learn how to promote the use of an incident learning system in a clinic.

Learn how to convert “event reporting” into “incident learning”.

See examples of practice changes that have come out of learning systems.

Learn how the RO‐ILS system can be used as a primary internal learning system.

Learn how to create succinct, meaningful reports useful to outside readers.

Gary Ezzell chairs the AAPM committee overseeing RO‐ILS and has received an honorarium from ASTRO for working on the committee reviewing RO‐ILS reports.

Derek Brown is a director of TreatSafely.org.

Brett Miller has previously received travel expenses and an honorarium from Varian.

Phillip Beron has nothing to report.
TU‐CD‐BRD‐02: Henry Ford Hospital System Experience, with Focus On Motivating and Reviewing
Authors: Miller B.
Published: June 2015

It has long been standard practice in radiation oncology to report internally when a patient's treatment has not gone as planned and to report events to regulatory agencies when legally required. Most potential errors are caught early and never affect the patient. Quality assurance steps routinely prevent errors from reaching the patient, and these “near misses” are much more frequent than treatment errors. A growing number of radiation oncology facilities have implemented incident learning systems to report and analyze both errors and near misses. Using the term “incident learning” instead of “event reporting” emphasizes the need to use these experiences to change the practice and make future errors less likely and promote an educational, non‐punitive environment.

There are challenges in making such a system practical and effective. Speakers from institutions of different sizes and practice environments will share their experiences on how to make such a system work and what benefits their clinics have accrued. Questions that will be addressed include:

How to create a system that is easy for front line staff to access

How to motivate staff to report

How to promote the system as positive and educational and not punitive or demeaning

How to organize the team for reviewing and responding to reports

How to prioritize which reports to discuss in depth

How not to dismiss the rest

How to identify underlying causes

How to design corrective actions and implement change

How to develop useful statistics and analysis tools

How to coordinate a departmental system with a larger risk management system

How to do this without a dedicated quality manager

Some speakers’ experience is with in‐house systems and some will share experience with the AAPM/ASTRO national Radiation Oncology Incident Learning System (RO‐ILS). Reports intended to be of value nationally need to be comprehensible to outsiders; examples of useful reports will be shown.

There will be ample time set aside for audience members to contribute to the discussion.

Learning Objectives:

Learn how to promote the use of an incident learning system in a clinic.

Learn how to convert “event reporting” into “incident learning”.

See examples of practice changes that have come out of learning systems.

Learn how the RO‐ILS system can be used as a primary internal learning system.

Learn how to create succinct, meaningful reports useful to outside readers.

Gary Ezzell chairs the AAPM committee overseeing RO‐ILS and has received an honorarium from ASTRO for working on the committee reviewing RO‐ILS reports.

Derek Brown is a director of TreatSafely.org.

Brett Miller has previously received travel expenses and an honorarium from Varian.

Phillip Beron has nothing to report.
TU‐CD‐BRB‐05: Radiation Damage Signature of White Matter Fiber Bundles Using Diffusion Tensor Imaging (DTI)
Authors: Zhu T , Chapman C , Tsien C , Lawrence T , Cao Y
Published: June 2015

Purpose:

To develop an automated and scalable approach and identify temporal, spatial and dosimetric patterns of radiation damage of white matter (WM) fibers following partial brain irradiation.

Methods:

An automated and scalable approach was developed to extract DTI features of 22 major WM fibers from 33 patients with low‐grade/benign tumors treated by radiation therapy (RT). DTI scans of the patients were performed pre‐RT, 3‐ and 6‐week during RT, and 1, 6 and 18 months after RT. The automated tractography analysis was applied to 198 datasets as: (1) intra‐subject registration of longitudinal DTI, (2) spatial normalization of individual‐patient DTI to the Johns Hopkins WM Atlas, (3) automatic fiber tracking regulated by the WM Atlas, and (4) segmentation of WM into 22 major tract profiles. Longitudinal percentage changes in fractional anisotropy (FA), and mean, axial and radial diffusivity (MD/AD/RD) of each tract from pre‐RT were quantified and correlated to 95%, 90% and 80% percentiles of doses and mean doses received by the tract. Heatmaps were used to identify clusters of significant correlation and reveal temporal, spatial and dosimetric signatures of WM damage. A multivariate linear regression was further carried out to determine influence of clinical factors.

Results:

Of 22 tracts, AD/MD changes in 12 tracts had significant correlation with doses, especially at 6 and 18 months post‐RT, indicating progressive radiation damage after RT. Most interestingly, the DTI‐index changes in the elongated tracts were associated with received maximum doses, suggesting a serial‐structure behavior; while short association fibers were affected by mean doses, indicating a parallel‐structure response.

Conclusion:

Using an automated DTI‐tractography analysis of whole brain WM fibers, we reveal complex radiation damage patterns of WM fibers. Damage in WM fibers that play an important role in the neural network could be associated with late neurocognitive function declines after brain irradiation.

NIH NS064973
TU‐CD‐BRB‐07: Identification of Associations Between Radiologist‐Annotated Imaging Features and Genomic Alterations in Breast Invasive Carcinoma, a TCGA Phenotype Research Group Study
Authors: Rao A , Net J , Brandt K , Huang E , Freymann J , Burnside E , Kirby J , Morris E , Bonaccio E , Giger M , Jaffe C , Ganott M , Sutton E , Le‐Petross H , Zuley M , Dogan B , Whitman G
Published: June 2015

Purpose:

To determine associations between radiologist‐annotated MRI features and genomic measurements in breast invasive carcinoma (BRCA) from the Cancer Genome Atlas (TCGA).

Methods:

98 TCGA patients with BRCA were assessed by a panel of radiologists (TCGA Breast Phenotype Research Group) based on a variety of mass and non‐mass features according to the Breast Imaging Reporting and Data System (BI‐RADS). Batch corrected gene expression data was obtained from the TCGA Data Portal. The Kruskal‐Wallis test was used to assess correlations between categorical image features and tumor‐derived genomic features (such as gene pathway activity, copy number and mutation characteristics). Image‐derived features were also correlated with estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2/neu) status. Multiple hypothesis correction was done using Benjamini‐Hochberg FDR. Associations at an FDR of 0.1 were selected for interpretation.

Results:

ER status was associated with rim enhancement and peritumoral edema. PR status was associated with internal enhancement. Several components of the PI3K/Akt pathway were associated with rim enhancement as well as heterogeneity. In addition, several components of cell cycle regulation and cell division were associated with imaging characteristics.TP53 and GATA3 mutations were associated with lesion size. MRI features associated with TP53 mutation status were rim enhancement and peritumoral edema. Rim enhancement was associated with activity of RB1, PIK3R1, MAP3K1, AKT1,PI3K, and PIK3CA. Margin status was associated with HIF1A/ARNT, Ras/ GTP/PI3K, KRAS, and GADD45A. Axillary lymphadenopathy was associated with RB1 and BCL2L1. Peritumoral edema was associated with Aurora A/GADD45A, BCL2L1, CCNE1, and FOXA1. Heterogeneous internal nonmass enhancement was associated with EGFR, PI3K, AKT1, HF/MET, and EGFR/Erbb4/neuregulin 1. Diffuse nonmass enhancement was associated with HGF/MET/MUC20/SHIP, and HGF/MET/RANBP9. Linear nonmass enhancement was associated with PIK3R1 and AKT activity.

Conclusion:

MRI‐genomic association analysis revealed that several BRCA‐associated gene features were associated with radiologist‐annotated image features.