bluuebunny/crossref_metadata_2025 huggingface dataset:
SU‐G‐TeP4‐07: Automatic EPID‐Based 2D Measurement of MLC Leaf Offset as a Quality Control Tool
Authors: Ritter T , Schultz B , Kim G , Barnes M , Perez M , Farrey K , Popple R , Greer P , Moran J
Published: July 2016

Purpose:

The MLC dosimetric leaf gap (DLG) and transmission are measured parameters which impact the dosimetric accuracy of IMRT and VMAT plans. This investigation aims to develop an efficient and accurate routine constancy check of the physical DLG in two dimensions.

Methods:

The manufacturer's recommended DLG measurement method was modified by using 5 fields instead of 11 and by utilizing the Electronic Portal Imaging Device (EPID). Validations were accomplished using an ion chamber (IC) in solid water and a 2D IC array. EPID data was collected for 6 months on multiple TrueBeam linacs using both Millennium and HD MLCs at 5 different clinics in an international consortium. Matlab code was written to automatically analyze the images and calculate the 2D results. Sensitivity was investigated by introducing deliberate leaf position errors. MLC calibration and initialization history was recorded to allow quantification of their impact. Results were analyzed using statistical process control (SPC).

Results:

The EPID method took approximately 5 minutes. Due to detector response, the EPID measured DLG and transmission differed from the IC values but were reproducible and consistent with changes measured using the ICs. For the Millennium MLC, the EPID measured DLG and transmission were both consistently lower than IC results. The EPID method was implemented as leaf offset and transmission constancy tests (LOC and TC). Based on 6 months of measurements, the initial leaf‐specific action thresholds for changes from baseline were set to 0.1 mm. Upper and lower control limits for variation were developed for each machine.

Conclusion:

Leaf offset and transmission constancy tests were implemented on Varian HD and Millennium MLCs using an EPID and found to be efficient and accurate. The test is effective for monitoring MLC performance using dynamic delivery and performing process control on the DLG in 2D, thus enhancing dosimetric accuracy.

This work was supported by a grant from Varian Medical Systems.
SU‐G‐TeP4‐08: Automating the Verification of Patient Treatment Parameters
Authors: DiCostanzo D , Ayan A , Woollard J , Gupta N
Published: July 2016

Purpose:

To automate the daily verification of each patient's treatment by utilizing the trajectory log files (TLs) written by the Varian TrueBeam linear accelerator while reducing the number of false positives including jaw and gantry positioning errors, that are displayed in the Treatment History tab of Varian's Chart QA module.

Methods:

Small deviations in treatment parameters are difficult to detect in weekly chart checks, but may be significant in reducing delivery errors, and would be critical if detected daily. Software was developed in house to read TLs. Multiple functions were implemented within the software that allow it to operate via a GUI to analyze TLs, or as a script to run on a regular basis. In order to determine tolerance levels for the scripted analysis, 15,241 TLs from seven TrueBeams were analyzed. The maximum error of each axis for each TL was written to a CSV file and statistically analyzed to determine the tolerance for each axis accessible in the TLs to flag for manual review. The software/scripts developed were tested by varying the tolerance values to ensure veracity. After tolerances were determined, multiple weeks of manual chart checks were performed simultaneously with the automated analysis to ensure validity.

Results:

The tolerance values for the major axis were determined to be, 0.025 degrees for the collimator, 1.0 degree for the gantry, 0.002cm for the y‐jaws, 0.01cm for the x‐jaws, and 0.5MU for the MU. The automated verification of treatment parameters has been in clinical use for 4 months. During that time, no errors in machine delivery of the patient treatments were found.

Conclusion:

The process detailed here is a viable and effective alternative to manually checking treatment parameters during weekly chart checks.
SU‐G‐TeP4‐13: Interfraction Treatment Monitoring Using Integrated Invivo EPID Images
Authors: Defoor D , Papanikolaou N , Stathakis S
Published: July 2016

Purpose:

To investigate inter‐fraction differences of dose delivery by analyzing portal images acquired during treatment and implement an automated system to generate a report for each fraction. Large differences in images between fractions can alert the physicist of possible machine performance issues or patient set‐up errors.

Methods:

A Varian Novalis Tx equipped with a HD120 MLC and aS1000 electronic portal imaging device (EPID) was used in our study. EPID images are acquired in continuous acquisition mode for 32 volumetric arc therapy (VMAT) patients. The images are summed to create an image for each arc and a single image for each fraction. The first fraction is designated as the reference unless a machine error prevented acquisition of all images. The images for each beam as well as the fraction image are compared using gamma analysis at 1%/1mm, 2%/2mm and 3%/3mm. A report is then generated using an in house MatLab program containing the comparison for the current fraction as well as a history of previous fractions. The reports are automatically sent via email to the physicist for review. Fractions in which the total number of images was not within 5% of the reference number of images were not included in the results.

Results:

91 of the 182 fractions recorded an image count within 5% of the reference. Gamma averages over all fractions and patients were 96.2% ±0.8% at 3%/3mm, 92.9% ±1% at 2%/2mm and 80.6% ±1.8% at 1%/1mm. The SD between fractions for each patient ranged from .004% to 10.4%. Of the 91 fractions 3 flagged due to low gamma values. After further investigation no significant errors were found.

Conclusion:

This toolkit can be used for in‐vivo monitoring of treatment plan delivery an alert the physics staff of any inter‐fraction discrepancies that may require further investigation.
SU‐G‐TeP4‐15: The Roucoulette: A Set of Quality Control Tests for Dynamic Trajectory (4Pi) Treatment Delivery Techniques
Authors: Teke T
Published: July 2016

Purpose:

To present and validate a set of quality control tests for trajectory treatment delivery using synchronized dynamic couch (translation and rotation), MLC and collimator motion.

Methods:

The quality control tests are based on the Picket fence test, which consist of 5 narrow band 2mm width spaced at 2.5cm intervals, and adds progressively synchronized dynamic motions. The tests were exposed on GafChromic EBT3 films. The first test is a regular (no motion and MLC static while beam is on) Picket Fence test used as baseline. The second test includes simultaneous collimator and couch rotation, each stripe corresponding to a different rotation speed. Errors in these tests were introduced (0.5 degree and 1 degree error in rotation synchronization) to assess the error sensitivity of this test. The second test is similar to the regular Picket Fence but now including dynamic MLC motion and couch translation (including acceleration during delivery) while the beam is on. Finally in the third test, which is a combination of the first and second test, the Picket Fence pattern is delivered using synchronized collimator and couch rotation and synchronized dynamic MLC and couch translation including acceleration. Films were analyzed with FilmQA Pro.

Results:

The distance between the peaks in the dose profile where measured (18.5cm away from the isocentre in the inplane direction where non synchronized rotation would have the largest effect) and compared to the regular Picket Fence tests. For well synchronized motions distances between peaks where between 24.9–25.4 mm identical to the regular Picket Fence test. This range increased to 24.4–26.4mm and 23.4–26.4mm for 0.5 degree and 1 degree error respectively. The amplitude also decreased up to 15% when errors are introduced.

Conclusion:

We demonstrated that the Roucoulette tests can be used as a quality control tests for trajectory treatment delivery using synchronized dynamic motion.
MO‐AB‐204‐00: Interoperability in Radiation Oncology: IHE‐RO Committee Update
Authors: Hadley Scott
Published: July 2016

You've experienced the frustration: vendor A's device claims to work with vendor B's device, but the practice doesn't match the promise. Getting devices working together is the hidden art that Radiology and Radiation Oncology staff have to master. To assist with that difficult process, the Integrating the Healthcare Enterprise (IHE) effort was established in 1998, with the coordination of the Radiological Society of North America.

Integrating the Healthcare Enterprise (IHE) is a consortium of healthcare professionals and industry partners focused on improving the way computer systems interconnect and exchange information. This is done by coordinating the use of published standards like DICOM and HL7. Several clinical and operational IHE domains exist in the healthcare arena, including Radiology and Radiation Oncology. The ASTRO‐sponsored IHE Radiation Oncology (IHE‐RO) domain focuses on radiation oncology specific information exchange. This session will explore the IHE Radiology and IHE RO process for;

IHE solicitation process for new profiles.

Improving the way computer systems interconnect and exchange information in the healthcare enterprise

Supporting interconnectivity descriptions and proof of adherence by vendors

Testing and assuring the vendor solutions to connectivity problems.

Including IHE profiles in RFPs for future software and hardware purchases.

Learning Objectives:

Understand IHE role in improving interoperability in health care.

Understand process of profile development and implantation.

Understand how vendors prove adherence to IHE RO profiles.

S. Hadley, ASTRO Supported Activity
MO‐AB‐204‐01: IHE RO Overview
Authors: Hadley S.
Published: July 2016

You've experienced the frustration: vendor A's device claims to work with vendor B's device, but the practice doesn't match the promise. Getting devices working together is the hidden art that Radiology and Radiation Oncology staff have to master. To assist with that difficult process, the Integrating the Healthcare Enterprise (IHE) effort was established in 1998, with the coordination of the Radiological Society of North America.

Integrating the Healthcare Enterprise (IHE) is a consortium of healthcare professionals and industry partners focused on improving the way computer systems interconnect and exchange information. This is done by coordinating the use of published standards like DICOM and HL7. Several clinical and operational IHE domains exist in the healthcare arena, including Radiology and Radiation Oncology. The ASTRO‐sponsored IHE Radiation Oncology (IHE‐RO) domain focuses on radiation oncology specific information exchange. This session will explore the IHE Radiology and IHE RO process for;

IHE solicitation process for new profiles.

Improving the way computer systems interconnect and exchange information in the healthcare enterprise

Supporting interconnectivity descriptions and proof of adherence by vendors

Testing and assuring the vendor solutions to connectivity problems.

Including IHE profiles in RFPs for future software and hardware purchases.

Learning Objectives:

Understand IHE role in improving interoperability in health care.

Understand process of profile development and implantation.

Understand how vendors prove adherence to IHE RO profiles.

S. Hadley, ASTRO Supported Activity
MO‐AB‐BRA‐07: Low Dose Imaging with Avalanche Amorphous Selenium Flat Panel Imager
Authors: Scheuermann J , Howansky A , Goldan A , Leveille S , Tousignant O , Tanioka K , Zhao W
Published: July 2016

Purpose:

We present the first active matrix flat panel imager (AMFPI) capable of producing x‐ray quantum noise limited images at low doses by overcoming the electronic noise through signal amplification by photoconductive avalanche gain (gav). The indirect detector fabricated uses an optical sensing layer of amorphous selenium (a‐Se) known as High‐Gain Avalanche Rushing Photoconductor (HARP). The detector design is called Scintillator HARP (SHARP)‐AMFPI. This is the first image sensor to utilize solid‐state HARP technology.

Methods:

The detector's electronic readout is a 24 × 30 cm2 array of thin film transistors (TFT) with a pixel pitch of 85 µm. The HARP structure consists of a 15 µm layer of a‐Se isolated from the high voltage (HV) and signal electrode by a 2 µm thick hole blocking layer and electron blocking layer, respectively, to reduce dark current. A 150 µm thick structured CsI scintillator with reflective backing and a fiber optic faceplate (FOP) was coupled to the semi‐transparent HV bias electrode of the HARP structure. Images were acquired using a 30 kVp Mo/Mo spectrum typically used in mammography.

Results:

Optical sensitivity measurements demonstrate that gav = 76 ± 5 can be achieved over the entire active area of the detector. At a constant dose to the detector of 6.67 µGy, image quality increases with gav until the effective electronic noise is negligible. Quantum noise limited images can be obtained with doses as low as 0.18 µGy.

Conclusion:

We demonstrate the feasibility of utilizing avalanche gain to overcome electronic noise. The indirect detector fabricated is the first solid‐state imaging sensor to use HARP, and the largest active area HARP sensor to date. Our future work is to improve charge transport within the HARP structure and utilize a transparent HV electrode.
MO‐AB‐206‐01: PET Physics
Authors: Turkington T.
Published: July 2016

This education session will cover the physics and operation principles of gamma cameras and PET scanners.

The first talk will focus on PET imaging. An overview of the principles of PET imaging will be provided, including positron decay physics, and the transition from 2D to 3D imaging. More recent advances in hardware and software will be discussed, such as time‐of‐flight imaging, and improvements in reconstruction algorithms that provide for options such as depth‐of‐interaction corrections. Quantitative applications of PET will be discussed, as well as the requirements for doing accurate quantitation. Relevant performance tests will also be described.

Learning Objectives:

Be able to describe basic physics principles of PET and operation of PET scanners.

Learn about recent advances in PET scanner hardware technology.

Be able to describe advances in reconstruction techniques and improvements

Be able to list relevant performance tests.

The second talk will focus on gamma cameras. The Nuclear Medicine subcommittee has charged a task group (TG177) to develop a report on the current state of physics testing of gamma cameras, SPECT, and SPECT/CT systems. The report makes recommendations for performance tests to be done for routine quality assurance, annual physics testing, and acceptance tests, and identifies those needed satisfy the ACR accreditation program and The Joint Commission imaging standards. The report is also intended to be used as a manual with detailed instructions on how to perform tests under widely varying conditions.

Learning Objectives:

At the end of the presentation members of the audience will:

Be familiar with the tests recommended for routine quality assurance, annual physics testing, and acceptance tests of gamma cameras for planar imaging.

Be familiar with the tests recommended for routine quality assurance, annual physics testing, and acceptance tests of SPECT systems.

Be familiar with the tests of a SPECT/CT system that include the CT images for SPECT reconstructions.

Become knowledgeable of items to be included in annual acceptance testing reports including CT dosimetry and PACS monitor measurements.

T. Turkington, GE Healthcare
MO‐A‐209‐02: A Tale of Two Journals: Open‐Access and Subscription‐Based Publications
Authors: Bourland J.
Published: July 2016

Scientific publishing is a major endeavor of the AAPM. Although publishing requires substantial resources, it has the potential to generate both reputation and revenue to further the missions of our society. The AAPM owns and publishes two journals: Medical Physics and the Journal of Applied Clinical Medical Physics (JACMP). Medical Physics, with the tagline “The international journal of medical physics research and practice,” publishes research concerned with the application of physics and mathematics to the solution of problems in medicine and human biology, with an emphasis on theoretical and experimental approaches. The JACMP is an applied journal that publishes papers designed to help clinical medical physicists perform their responsibilities more effectively and efficiently for the greater benefit of patients. The two journals reflect two different missions, reach two different (yet often overlapping) audiences, engage two different publication approaches, and operate under two different financial models. A journal must serve both “producers” (authors who submit manuscripts to – and ultimately have their work published in – the journal) and “consumers” (readers – either individuals who access journal content or subscribing institutions that make the journal's content available to its members). Any viable publication model and cost‐recovery structure must satisfy the interests of both groups without sacrificing the needs of the scientific community. The purpose of this symposium is to explore the roles of the AAPM's two journals in advancing the scientific and clinical missions of the society and to understand the complex interplay of economic factors that impact financial decisions governing the journals and the returns they bring to the AAPM.

Learning Objectives:

Appreciate the complementary roles of Medical Physics and JACMP in advancing the scientific and clinical missions of the AAPM.

Understand AAPM resources committed to the two journals and the return on these investments.

Understand the role of the AAPM's Journals Business Management Committee in the financial stability of the two journals.

Explore the potential benefits and pitfalls of various economic and publication models for the two journals.

J. Bourland, Member, Journals Business Management Committee, AAPM.
MO‐B‐201‐01: Overcoming the Challenges of Motion Management in Current Lung SBRT Practice
Authors: Shang C.
Published: July 2016

The motion management in stereotactic body radiation therapy (SBRT) is a key to success for a SBRT program, and still an on‐going challenging task. A major factor is that moving structures behave differently than standing structures when examined by imaging modalities, and thus require special considerations and employments. Understanding the motion effects to these different imaging processes is a prerequisite for a decent motion management program. The commonly used motion control techniques to physically restrict tumor motion, if adopted correctly, effectively increase the conformity and accuracy of hypofractionated treatment. The effective application of such requires one to understand the mechanics of the application and the related physiology especially related to respiration. The image‐guided radiation beam control, or tumor tracking, further realized the endeavor for precision‐targeting. During tumor tracking, the respiratory motion is often constantly monitored by non‐ionizing beam sources using the body surface as its surrogate. This then has to synchronize with the actual internal tumor motion. The latter is often accomplished by stereo X‐ray imaging or similar techniques. With these advanced technologies, one may drastically reduce the treated volume and increase the clinicians’ confidence for a high fractional ablative radiation dose. However, the challenges in implementing the motion management may not be trivial and is dependent on each clinic case. This session of presentations is intended to provide an overview of the current techniques used in managing the tumor motion in SBRT, specifically for routine lung SBRT, proton based treatments, and newly‐developed MR guided RT.

Learning Objectives:

Through this presentation, the audience will

understand basic roles of commonly used imaging modalities for lung cancer studies;

familiarize the major advantages and limitations of each discussed motion control methods;

familiarize the major advantages and limitations of each discussed radiation beam control methodology and tumor tacking method;

understand the key points in motion management for a high quality SBRT program.
MO‐B‐BRC‐00: Prostate HDR Treatment Planning ‐ Considering Different Imaging Modalities
Authors: Prisciandaro Joann
Published: July 2016

Brachytherapy has proven to be an effective treatment option for prostate cancer. Initially, prostate brachytherapy was delivered through permanently implanted low dose rate (LDR) radioactive sources; however, high dose rate (HDR) temporary brachytherapy for prostate cancer is gaining popularity. Needle insertion during prostate brachytherapy is most commonly performed under ultrasound (U/S) guidance; however, treatment planning may be performed utilizing several imaging modalities either in an intra‐ or post‐operative setting. During intra‐operative prostate HDR, the needles are imaged during implantation, and planning may be performed in real time. At present, the most common imaging modality utilized for intra‐operative prostate HDR is U/S. Alternatively, in the post‐operative setting, following needle implantation, patients may be simulated with computed tomography (CT) or magnetic resonance imaging (MRI). Each imaging modality and workflow provides its share of benefits and limitations.

Prostate HDR has been adopted in a number of cancer centers across the nation. In this educational session, we will explore the role of U/S, CT, and MRI in HDR prostate brachytherapy. Example workflows and operational details will be shared, and we will discuss how to establish a prostate HDR program in a clinical setting.

Learning Objectives:

Review prostate HDR techniques based on the imaging modality

Discuss the challenges and pitfalls introduced by the three imagebased options for prostate HDR brachytherapy

Review the QA process and learn about the development of clinical workflows for these imaging options at different institutions
MO‐B‐BRB‐00: Three Dimensional Dosimetry
Authors: Schreiner L. John
Published: July 2016

Full three‐dimensional (3D) dosimetry using volumetric chemical dosimeters probed by 3D imaging systems has long been a promising technique for the radiation therapy clinic, since it provides a unique methodology for dose measurements in the volume irradiated using complex conformal delivery techniques such as IMRT and VMAT. To date true 3D dosimetry is still not widely practiced in the community; it has been confined to centres of specialized expertise especially for quality assurance or commissioning roles where other dosimetry techniques are difficult to implement. The potential for improved clinical applicability has been advanced considerably in the last decade by the development of improved 3D dosimeters (e.g., radiochromic plastics, radiochromic gel dosimeters and normoxic polymer gel systems) and by improved readout protocols using optical computed tomography or magnetic resonance imaging.

In this session, established users of some current 3D chemical dosimeters will briefly review the current status of 3D dosimetry, describe several dosimeters and their appropriate imaging for dose readout, present workflow procedures required for good dosimetry, and analyze some limitations for applications in select settings. We will review the application of 3D dosimetry to various clinical situations describing how 3D approaches can complement other dose delivery validation approaches already available in the clinic. The applications presented will be selected to inform attendees of the unique features provided by full 3D techniques.

Learning Objectives:

L. John Schreiner: Background and Motivation

Understand recent developments enabling clinically practical 3D dosimetry,

Appreciate 3D dosimetry workflow and dosimetry procedures, and

Observe select examples from the clinic.

Sofie Ceberg: Application to dynamic radiotherapy

Observe full dosimetry under dynamic radiotherapy during respiratory motion, and

Understand how the measurement of high resolution dose data in an irradiated volume can help understand interplay effects during TomoTherapy or VMAT.

Titania Juang: Special techniques in the clinic and research

Understand the potential for 3D dosimetry in validating dose accumulation in deformable systems, and

Observe the benefits of high resolution measurements for precision therapy in SRS and in MicroSBRT for small animal irradiators

Geoffrey S. Ibbott: 3D Dosimetry in end‐to‐end dosimetry QA

Understand the potential for 3D dosimetry for end‐to‐end radiation therapy process validation in the in‐house and external credentialing setting.

Canadian Institutes of Health Research; L. Schreiner, Modus QA, London, ON, Canada; T. Juang, NIH R01CA100835
MO‐B‐BRB‐01: 3D Dosimetry in the Clinic: Background and Motivation
Authors: Schreiner L.
Published: July 2016

Full three‐dimensional (3D) dosimetry using volumetric chemical dosimeters probed by 3D imaging systems has long been a promising technique for the radiation therapy clinic, since it provides a unique methodology for dose measurements in the volume irradiated using complex conformal delivery techniques such as IMRT and VMAT. To date true 3D dosimetry is still not widely practiced in the community; it has been confined to centres of specialized expertise especially for quality assurance or commissioning roles where other dosimetry techniques are difficult to implement. The potential for improved clinical applicability has been advanced considerably in the last decade by the development of improved 3D dosimeters (e.g., radiochromic plastics, radiochromic gel dosimeters and normoxic polymer gel systems) and by improved readout protocols using optical computed tomography or magnetic resonance imaging.

In this session, established users of some current 3D chemical dosimeters will briefly review the current status of 3D dosimetry, describe several dosimeters and their appropriate imaging for dose readout, present workflow procedures required for good dosimetry, and analyze some limitations for applications in select settings. We will review the application of 3D dosimetry to various clinical situations describing how 3D approaches can complement other dose delivery validation approaches already available in the clinic. The applications presented will be selected to inform attendees of the unique features provided by full 3D techniques.

Learning Objectives:

L. John Schreiner: Background and Motivation

Understand recent developments enabling clinically practical 3D dosimetry,

Appreciate 3D dosimetry workflow and dosimetry procedures, and

Observe select examples from the clinic.

Sofie Ceberg: Application to dynamic radiotherapy

Observe full dosimetry under dynamic radiotherapy during respiratory motion, and

Understand how the measurement of high resolution dose data in an irradiated volume can help understand interplay effects during TomoTherapy or VMAT.

Titania Juang: Special techniques in the clinic and research

Understand the potential for 3D dosimetry in validating dose accumulation in deformable systems, and

Observe the benefits of high resolution measurements for precision therapy in SRS and in MicroSBRT for small animal irradiators

Geoffrey S. Ibbott: 3D Dosimetry in end‐to‐end dosimetry QA

Understand the potential for 3D dosimetry for end‐to‐end radiation therapy process validation in the in‐house and external credentialing setting.

Canadian Institutes of Health Research; L. Schreiner, Modus QA, London, ON, Canada; T. Juang, NIH R01CA100835
MO‐B‐BRB‐04: 3D Dosimetry in End‐To‐End Dosimetry QA
Authors: Ibbott G.
Published: July 2016

Full three‐dimensional (3D) dosimetry using volumetric chemical dosimeters probed by 3D imaging systems has long been a promising technique for the radiation therapy clinic, since it provides a unique methodology for dose measurements in the volume irradiated using complex conformal delivery techniques such as IMRT and VMAT. To date true 3D dosimetry is still not widely practiced in the community; it has been confined to centres of specialized expertise especially for quality assurance or commissioning roles where other dosimetry techniques are difficult to implement. The potential for improved clinical applicability has been advanced considerably in the last decade by the development of improved 3D dosimeters (e.g., radiochromic plastics, radiochromic gel dosimeters and normoxic polymer gel systems) and by improved readout protocols using optical computed tomography or magnetic resonance imaging.

In this session, established users of some current 3D chemical dosimeters will briefly review the current status of 3D dosimetry, describe several dosimeters and their appropriate imaging for dose readout, present workflow procedures required for good dosimetry, and analyze some limitations for applications in select settings. We will review the application of 3D dosimetry to various clinical situations describing how 3D approaches can complement other dose delivery validation approaches already available in the clinic. The applications presented will be selected to inform attendees of the unique features provided by full 3D techniques.

Learning Objectives:

L. John Schreiner: Background and Motivation

Understand recent developments enabling clinically practical 3D dosimetry,

Appreciate 3D dosimetry workflow and dosimetry procedures, and

Observe select examples from the clinic.

Sofie Ceberg: Application to dynamic radiotherapy

Observe full dosimetry under dynamic radiotherapy during respiratory motion, and

Understand how the measurement of high resolution dose data in an irradiated volume can help understand interplay effects during TomoTherapy or VMAT.

Titania Juang: Special techniques in the clinic and research

Understand the potential for 3D dosimetry in validating dose accumulation in deformable systems, and

Observe the benefits of high resolution measurements for precision therapy in SRS and in MicroSBRT for small animal irradiators

Geoffrey S. Ibbott: 3D Dosimetry in end‐to‐end dosimetry QA

Understand the potential for 3D dosimetry for end‐to‐end radiation therapy process validation in the in‐house and external credentialing setting.

Canadian Institutes of Health Research; L. Schreiner, Modus QA, London, ON, Canada; T. Juang, NIH R01CA100835
MO‐DE‐204‐03: Radiology Dose Optimisation ‐ An Australian Perspective
Authors: Schick D.
Published: July 2016

The main topic of the session is to show how dose optimization is being implemented in various regions of the world, including Europe, Australia, North America and other regions.

A multi‐national study conducted under International Atomic Energy Agency (IAEA) across more than 50 less resourced countries gave insight into patient radiation doses and safety practices in CT, mammography, radiography and interventional procedures, both for children and adults. An important outcome was the capability development on dose assessment and management.

An overview of recent European projects related to CT radiation dose and optimization both to adults and children will be presented. Existing data on DRLs together with a European methodology proposed on establishing and using DRLs for paediatric radiodiagnostic imaging and interventional radiology practices will be shown.

Compared with much of Europe at least, many Australian imaging practices are relatively new to the task of diagnostic imaging dose optimisation. In 2008 the Australian Government prescribed a requirement to periodically compare patient radiation doses with diagnostic reference levels (DRLs), where DRLs have been established. Until recently, Australia had only established DRLs for computed tomography (CT). Regardless, both professional society and individual efforts to improved data collection and develop optimisation strategies across a range of modalities continues. Progress in this field, principally with respect to CT and interventional fluoroscopy will be presented.

In the US, dose reduction and optimization efforts for computed tomography have been promoted and mandated by several organizations and accrediting entities. This presentation will cover the general motivation, implementation, and implications of such efforts.

Learning Objectives:

Understand importance of the dose optimization in Diagnostic Radiology.

See how this goal is achieved in different regions of the World.

Learn about the global trend in the dose optimization and future prospectives.

M. Rehani, The work was a part of the work of IAEA where I was an employee and IAEA is a United Nations organization
MO‐DE‐204‐01: Radiation Doses in Over 50 Developing Countries of Asia, Africa, Eastern European and Latin America
Authors: Rehani M.
Published: July 2016

The main topic of the session is to show how dose optimization is being implemented in various regions of the world, including Europe, Australia, North America and other regions.

A multi‐national study conducted under International Atomic Energy Agency (IAEA) across more than 50 less resourced countries gave insight into patient radiation doses and safety practices in CT, mammography, radiography and interventional procedures, both for children and adults. An important outcome was the capability development on dose assessment and management.

An overview of recent European projects related to CT radiation dose and optimization both to adults and children will be presented. Existing data on DRLs together with a European methodology proposed on establishing and using DRLs for paediatric radiodiagnostic imaging and interventional radiology practices will be shown.

Compared with much of Europe at least, many Australian imaging practices are relatively new to the task of diagnostic imaging dose optimisation. In 2008 the Australian Government prescribed a requirement to periodically compare patient radiation doses with diagnostic reference levels (DRLs), where DRLs have been established. Until recently, Australia had only established DRLs for computed tomography (CT). Regardless, both professional society and individual efforts to improved data collection and develop optimisation strategies across a range of modalities continues. Progress in this field, principally with respect to CT and interventional fluoroscopy will be presented.

In the US, dose reduction and optimization efforts for computed tomography have been promoted and mandated by several organizations and accrediting entities. This presentation will cover the general motivation, implementation, and implications of such efforts.

Learning Objectives:

Understand importance of the dose optimization in Diagnostic Radiology.

See how this goal is achieved in different regions of the World.

Learn about the global trend in the dose optimization and future prospectives.

M. Rehani, The work was a part of the work of IAEA where I was an employee and IAEA is a United Nations organization
MO‐DE‐201‐01: Introduction to the MPLA and Emotional Competencies
Authors: Clements J.
Published: July 2016

Medical physicists possess technical knowledge and problem solving skills required to deliver high quality diagnosis and treatment in the clinic, to provide excellence in research, or to transfer expertise in industrial or regulatory environments. As the healthcare industry rapidly evolves, medical physicists must make a case for ensuring recognition of their value. One of many ways the AAPM is working to ensure stewardship of the profession is through development of the Medical Physics Leadership Academy (MPLA).

This session will provide an introduction to the MPLA and one of its focus areas of emotional intelligence. The session will make the case for emotional competencies in addition to technical competencies. MPLA work group representatives will share consolidated results from conducting 360 feedback assessments used to measure emotional competencies of medical physicists. Some emotional competencies contribute more to professional success than others, and the session will explain how to overcome shortcomings. Two specific emotional competencies will be covered: selfawareness and empathy.

Learning Objectives:

Understand the importance of medical physics leadership in the future of health care

Understand emotional intelligence and emotional competencies and ways they can be measured

Utilize self‐awareness and empathy to improve management of our own emotions and others
MO‐D‐BRC‐01: Memorial Lecture
Authors: Fraass B.
Published: July 2016

Treatment planning is a central part of radiation therapy, including delineation in tumor volumes and critical organs, setting treatment goals of prescription doses to the tumor targets and tolerance doses to the critical organs, and finally generation of treatment plans to meet the treatment goals. National groups like RTOG have led the effort to standardize treatment goals of the prescription doses to the tumor targets and tolerance doses to the critical organs based on accumulated knowledge from decades of abundant clinical trial experience. The challenge for each clinical department is how to achieve or surpass these set goals within the time constraints of clinical practice. Using fifteen testing cases from different treatment sites such as head and neck, prostate with and without pelvic lymph nodes, SBRT spine, we will present clinically utility of advanced planning tools, including knowledge based, automatic based, and multiple criteria based tools that are clinically implemented.

The objectives of this session are:

Understand differences among these three advanced planning tools

Provide clinical assessments on the utility of the advanced planning tools

Discuss clinical challenges of treatment planning with large variations in tumor volumes and their relationships with adjacent critical organs.

Ping Xia received research grant from Philips. Jackie Wu received research grant from Varian; P. Xia, Research support by Philips and Varian; Q. Wu, NIH, Varian Medical
MO‐D‐BRC‐03: Knowledge‐Based Planning
Authors: Wu Q.
Published: July 2016

Treatment planning is a central part of radiation therapy, including delineation in tumor volumes and critical organs, setting treatment goals of prescription doses to the tumor targets and tolerance doses to the critical organs, and finally generation of treatment plans to meet the treatment goals. National groups like RTOG have led the effort to standardize treatment goals of the prescription doses to the tumor targets and tolerance doses to the critical organs based on accumulated knowledge from decades of abundant clinical trial experience. The challenge for each clinical department is how to achieve or surpass these set goals within the time constraints of clinical practice. Using fifteen testing cases from different treatment sites such as head and neck, prostate with and without pelvic lymph nodes, SBRT spine, we will present clinically utility of advanced planning tools, including knowledge based, automatic based, and multiple criteria based tools that are clinically implemented.

The objectives of this session are:

Understand differences among these three advanced planning tools

Provide clinical assessments on the utility of the advanced planning tools

Discuss clinical challenges of treatment planning with large variations in tumor volumes and their relationships with adjacent critical organs.

Ping Xia received research grant from Philips. Jackie Wu received research grant from Varian; P. Xia, Research support by Philips and Varian; Q. Wu, NIH, Varian Medical
MO‐DE‐BRA‐02: SIMAC: A Simulation Tool for Teaching Linear Accelerator Physics
Authors: Carlone M , Harnett N , Harris W , Norrlinger B , MacPherson M , Lamey M , Anderson R , Oldham M
Published: July 2016

Purpose:

The first goal of this work is to develop software that can simulate the physics of linear accelerators (linac). The second goal is to show that this simulation tool is effective in teaching linac physics to medical physicists and linac service engineers.

Methods:

Linacs were modeled using analytical expressions that can correctly describe the physical response of a linac to parameter changes in real time. These expressions were programmed with a graphical user interface in order to produce an environment similar to that of linac service mode. The software, “SIMAC”, has been used as a learning aid in a professional development course 3 times (2014 – 2016) as well as in a physics graduate program. Exercises were developed to supplement the didactic components of the courses consisting of activites designed to reinforce the concepts of beam loading; the effect of steering coil currents on beam symmetry; and the relationship between beam energy and flatness.

Results:

SIMAC was used to teach 35 professionals (medical physicists; regulators; service engineers; 1 week course) as well as 20 graduate students (1 month project). In the student evaluations, 85% of the students rated the effectiveness of SIMAC as very good or outstanding, and 70% rated the software as the most effective part of the courses. Exercise results were collected showing that 100% of the students were able to use the software correctly. In exercises involving gross changes to linac operating points (i.e. energy changes) the majority of students were able to correctly perform these beam adjustments.

Conclusion:

Software simulation(SIMAC), can be used to effectively teach linac physics. In short courses, students were able to correctly make gross parameter adjustments that typically require much longer training times using conventional training methods.
TU‐AB‐BRC‐11: Moving a GPU‐OpenCL‐Based Monte Carlo (MC) Dose Engine Towards Routine Clinical Use: Automatic Beam Commissioning and Efficient Source Sampling
Authors: Tian Z , Li Y , Folkerts M , Jiang S , Jia X
Published: July 2016

Purpose:

We have previously developed a GPU‐OpenCL‐based MC dose engine named goMC with built‐in analytical linac beam model. To move goMC towards routine clinical use, we have developed an automatic beam‐commissioning method, and an efficient source sampling strategy to facilitate dose calculations for real treatment plans.

Methods:

Our commissioning method is to automatically adjust the relative weights among the sub‐sources, through an optimization process minimizing the discrepancies between calculated dose and measurements. Six models built for Varian Truebeam linac photon beams (6MV, 10MV, 15MV, 18MV, 6MVFFF, 10MVFFF) were commissioned using measurement data acquired at our institution. To facilitate dose calculations for real treatment plans, we employed inverse sampling method to efficiently incorporate MLC leaf‐sequencing into source sampling. Specifically, instead of sampling source particles control‐point by control‐point and rejecting the particles blocked by MLC, we assigned a control‐point index to each sampled source particle, according to MLC leaf‐open duration of each control‐point at the pixel where the particle intersects the iso‐center plane.

Results:

Our auto‐commissioning method decreased distance‐to‐agreement (DTA) of depth dose at build‐up regions by 36.2% averagely, making it within 1mm. Lateral profiles were better matched for all beams, with biggest improvement found at 15MV for which root‐mean‐square difference was reduced from 1.44% to 0.50%. Maximum differences of output factors were reduced to less than 0.7% for all beams, with largest decrease being from1.70% to 0.37% found at 10FFF. Our new sampling strategy was tested on a Head&Neck VMAT patient case. Achieving clinically acceptable accuracy, the new strategy could reduce the required history number by a factor of ∼2.8 given a statistical uncertainty level and hence achieve a similar speed‐up factor.

Conclusion:

Our studies have demonstrated the feasibility and effectiveness of our auto‐commissioning approach and new efficient source sampling strategy, implying the potential of our GPU‐based MC dose engine goMC for routine clinical use.
TU‐AB‐BRA‐02: An Efficient Atlas‐Based Synthetic CT Generation Method
Authors: Han X
Published: July 2016

Purpose:

A major obstacle for MR‐only radiotherapy is the need to generate an accurate synthetic CT (sCT) from MR image(s) of a patient for the purposes of dose calculation and DRR generation. We propose here an accurate and efficient atlas‐based sCT generation method, which has a computation speed largely independent of the number of atlases used.

Methods:

Atlas‐based sCT generation requires a set of atlases with co‐registered CT and MR images. Unlike existing methods that align each atlas to the new patient independently, we first create an average atlas and pre‐align every atlas to the average atlas space. When a new patient arrives, we compute only one deformable image registration to align the patient MR image to the average atlas, which indirectly aligns the patient to all pre‐aligned atlases. A patch‐based non‐local weighted fusion is performed in the average atlas space to generate the sCT for the patient, which is then warped back to the original patient space. We further adapt a PatchMatch algorithm that can quickly find top matches between patches of the patient image and all atlas images, which makes the patch fusion step also independent of the number of atlases used.

Results:

Nineteen brain tumour patients with both CT and T1‐weighted MR images are used as testing data and a leave‐one‐out validation is performed. Each sCT generated is compared against the original CT image of the same patient on a voxel‐by‐voxel basis. The proposed method produces a mean absolute error (MAE) of 98.6±26.9 HU overall. The accuracy is comparable with a conventional implementation scheme, but the computation time is reduced from over an hour to four minutes.

Conclusion:

An average atlas space patch fusion approach can produce highly accurate sCT estimations very efficiently. Further validation on dose computation accuracy and using a larger patient cohort is warranted. The author is a full time employee of Elekta, Inc.