bluuebunny/crossref_metadata_2025_split huggingface dataset:
TU‐C‐342‐04: Advances in Endovascular Image‐Guided Interventions
Authors: Rudin S , Hoffmann KR , Bednarek DR 
Published: July 2008

In a recent Medical Physics “Vision 2020” paper (Medical Physics 35(1): 301–309, Jan 2008), the authors reviewed the state of endovascular image‐guided interventions (EIGI) and offered some predictions for the future. Here we review the current status of the field and of some of these advances. First, endovascular devices (such as clot busting tools, stents and their catheter delivery systems, and blood flow modifiers) are becoming finer, more complex, and are enabling the replacement of invasive surgical procedures with minimally invasive EIGI procedures. Innovative methods of actuating motion at the catheter tip, such as the use of external magnetic fields, are being introduced. Second, along with improvements in devices, imaging systems that provide real‐time high‐resolution image guidance are being developed including a Solid State X‐ray Image Intensifier based on electron multiplying charge coupled devices (EMCCDs) that provide large on‐chip gain to overcome instrumentation noise such as that characteristic of current flat panel detectors. SSXIIs also have very high resolution capable of exceeding 10 lp/mm yet with no lag or ghosting. Third, the new high‐resolution region‐of‐interest (ROI) detectors can be used in combination with large conventional detectors for dual‐detector cone‐beam computer tomography (CB‐CT) to visualize ROIs within larger objects yet with minimal truncation artifact and with reduced integral dose. Fourth, during an interventional procedure, limited projection views can be taken to generate full 3D representations of the vasculature with accurate determination of vessel lumen morphology to enable computer fluid dynamic (CFD) calculations which in turn can be used to plan further EIGI treatment within the patient treatment time. Finally, as EIGI procedures become more complex, the consequent patient dose especially where improved image quality is implemented must be more carefully monitored. For example, we found that patient dose actually increased for certain electro‐physiology (EP) procedures performed in our EP Lab following replacement of a mobile c‐arm with a fixed unit capable of generating improved image quality. In conclusion, while progress is being made toward fulfilling the predictions made by the authors in the Vision 2020 paper published early in 2008, EIGI remains open to continuing exciting advancements.Educational Objectives:1. Appreciate the progress being made in improved EIGI devices and imaging systems.2. Understand the operation of new high‐resolution micro‐angiographic systems including the SSXII and the operation of dual‐detector ROI CB‐CT systems.3. Understand the role of limited view acquisition for providing 3D images.4. Appreciate the patient exposure burden during EIGI procedures.[Supported in part by NIH Grants R01 EB002873, R01 NS43924, R01 EB00842501, R01 HL52567, UB Foundation IRDF, and an equipment grant from Toshiba Medical Systems Corp.].
TU‐D‐AUD C‐03: Liquid Scintillators for 2D Photon Dosimetry
Authors: Poenisch F , Archambault L , Briere T , Sahoo N , Beddar S , Mohan R , Gillin M 
Published: July 2008

Purpose: Liquid scintillators have the potential of providing real‐time dosimetric information in 2D and even possibly in 3D. The purpose of this work is to study the performance of a liquid scintillator (LS) detector system for photon beam dosimetry. Method and Materials: The detector system consisted of a lucite tank (7×7×16 cm3), a camera objective and a cooled CCD type camera (Luca, Andor Technology, South Windsor, CT), which was shifted by 59 cm with respect to the center of the tank. The LS material BC‐531 (Saint‐Gobain, Newbury, OH) was used. The detector system was irradiated with 6‐MV photons on a Varian Clinac 21EX under standard conditions. Different field sizes, dose rates and camera light enhancement modes were measured and compared to the dose profiles of the treatment machine. Results: The light signal produced by the LS was slightly distorted by light scattering isotropically within the liquid and refraction at the tank interface. Taking into account this blurring we could reproduce the dose distribution. The LS material is nearly water equivalent. The detector system was also found to be dose rate independent. Using the electron magnification mode of the CCD camera we were also capable of measuring very low dose rates from an I‐125 seed. Conclusion: The present detector system is suitable for measuring 2D dose distributions under the conditions used in therapeutic photon treatments. Further investigations are underway to fully characterize this system to make it practical for routine clinical use.Supported by the NCI (1R01CA120198‐01A2).
TU‐E‐350‐01: New Member Symposium/Meet the Experts
Authors: Herman M 
Published: July 2008

The New Members Symposium will provide an introduction to the AAPM, our current officers, council chairs and operations. AAPM leaders will remain at the symposium to continue informal discussions following the brief opening presentations.The New Members Symposium is followed directly by the Meet the Experts sessions in the same room. Bill Hendee, Gary Barnes, Dan Low and Jim Hevezi, all individuals with many years of experience will address current issues and lead discussions on many medical physics aspects of Imaging Research, Imaging Clinical, Therapy Research and Therapy clinical.Educational Objectives:1. To introduce new members to the AAPM leadership and operations.2. To provide discussions with experts in medical physics
WE‐E‐AUD C‐06: 4D Imaging of Lung Cancer Patients Treated with Stereotactic Body Radiotherapy (SBRT): Assessment of Target Volumes
Authors: Ouyang I , Wen N , Chen Q , Babij D , Aref I , Ajlouni M , Movsas B , Chetty IJ 
Published: July 2008

Purpose: To compare target volumes assessed via 4D and free‐breathing CT scans for patients treated with peripheral lung lesions. Method and Materials: The target volumes of five lung cancer patients imaged using 4D‐CT and treated with hypo‐fractionated SBRT (12 Gy/Fxn × 4Fxn) were retrospectively analyzed. For each patient 6‐to‐8 CT datasets were acquired between inhale and exhale respiratory phases on a Philips 16 slice 4D‐CT scanner. The GTV was segmented on each dataset using a maximum‐intensity‐projection (MIP) method and an ITV (ITV4D), representing the composite of GTVs, was formed. The ITV4D was expanded uniformly 5mm to generate a PTV (PTV4D). The GTV was also contoured on the free‐breathing scan and expanded using population‐based margins of 5mm and 10mm in the axial and longitudinal planes, respectively, to form a free‐breathing‐based PTV (PTVFB), following RTOG ♯0236. Finally, a target volume defined as a composite of GTVs contoured on only the inhale and exhale datasets was generated to form the ITVInh_Exh. Results: For three of five patient images, PTV4D was substantially larger than PTVFB (average increase of 33%; max.=65%). In one case the volumes were equivalent and in the remaining case PTV4D was 11% smaller than PTVFB. Significant shape changes were also observed in some instances between PTV4D and PTVFB suggesting that PTVFB was improperly designed. The ITVInh_Exh was smaller than the ITV4D in all cases (mean=31%; max.= 78%, smaller) suggesting that the inhale and exhale breathing phases sometimes fail to capture the largest extents of tumor motion in the respiratory cycle. Conclusion: Results suggest that, based on 4D imaging, the use of population‐based margin expansions may not adequately account for tumor motion of peripheral lung tumors. This may be of increased consequence in the SBRT setting, where the overall effects of motion may be escalated given the small number of fractions.Acknowledgement_NIH‐R01‐CA106770.
TH‐A‐350‐01: Putting the A Into ADCL, the Role of the Calibration Laboratory Accreditation Sub‐Committee
Authors: McEwen M , Stevens D , Slowey T , Seuntjens J 
Published: July 2008

The Calibration Laboratory Accreditation Subcommittee (CLA) of the AAPM oversees the accreditation of the ADCLs (Accredited Dosimetry Calibration Laboratories) who provide calibration services to clinical users in North America and around the world. The AAPM accreditation is similar to other accreditation programs that use the international standard for calibration and testing laboratories (ISO17025) but with additional focus on technical competencies through a strict set of AAPM‐developed Criteria. The purpose of this accreditation is to provide users with the highest level of confidence in equipment calibrations which form the basis for radiation treatments in the clinic.The CLA is currently working towards obtaining recognition by the National Cooperation for Laboratory Accreditation (NACLA) that the accreditation program satisfies the ISO standard 17011. This standard covers accrediting bodies and one of its requirements is that AAPM develop a pool of trained assessors. The main of aim, therefore, of this presentation is to give potential assessors (who could be members of the AAPM outside of the CLA) an introduction to the accreditation process with particular focus on on‐site assessments. Accreditation by the CLA requires a site visit every four years in which every aspect of the laboratories performance (as related to calibration services) is assessed. Quality manuals and procedures are reviewed and sample calibrations witnessed to verify that the laboratories are continuing to provide the high quality of service demanded by the AAPM Criteria.Although this lecture is aimed specifically at a small sub‐group of AAPM members there is much in the discussion of quality systems and the audit process that would of value to a wider audience. The details may be different but the approach set out here (e.g. development and review of Quality Systems, gathering of objective evidence) can be applied to a variety of QA applications in clinics and elsewhere.Since it is not possible to cover the whole accreditation process in one lecture those interested in becoming assessors for the CLA should contact the lead author prior to the meeting for additional material to review.Educational Objectives:1. Understand the role of the CLA in the accreditation of the ADCLs.2. Understand the requirements of the AAPM Criteria for Accreditation.3. Understand the steps in the accreditation process.4. Understand how an accreditation audit should be carried out.
TH‐SAMS‐AUD B‐01: Introduction To: Quality Assurance for Advanced RT Technologies—The Challenge for RT Clinical Trials
Authors: Olch A 
Published: July 2008

We as medical physicists have a crucial role to play in ensuring that all patients on radiotherapy protocols are treated comparably. Without this comparability, the validity of outcome results from the pooled patient data may be jeopardized. Advances in radiation therapy technology and delivery techniques have naturally led to the desire to incorporate such new tools into clinical trials, yet standardized quality assurance (QA) procedures are not fully developed and widely practiced. Although several task groups within the AAPM have been formed to set standards for QA for these new technologies, a major challenge is to conduct clinical trials that involve both the old and new technologies without overwhelming individual physicists with additional testing. National and international multi‐institutional clinical trials uniquely challenge the medical physics community to maintain comparability while at the same time requiring or permitting patient treatments that incorporate advanced technologies such as IMRT, image guided radiotherapy, image fusion, and other techniques.The AAPM Working Group on Clinical Trials presents this continuing education symposium in order to discuss the efforts underway to design QA methods for advanced radiotherapy technologies especially in the context of clinical trials with the intent to address the issue of comparability and standardization of protocol data. We will present the work of Task Group 113, an important player in these efforts, on providing guidance as to physics practice standards for QA for radiotherapy clinical trials. The task group's recommendations on QA procedures and reporting methods are intended to facilitate highly consistent protocol treatments and data submission.The Working Group on clinical trials has identified several topics that pose significant challenges with respect to consistency of physics practices: dose calculations with heterogeneity corrections, localization verification, image fusion techniques, and the treatment of moving targets. In this course, the history and the current state of the art will be described for each topic. The discussion about these areas should be of interest whether or not one is involved in clinical trials.Educational Objectives:1. Understand the quality assurance issues facing Medical Physicists using advanced technologies and how these relate to clinical trial data validity.2. Learn what Task Group 113 is doing to address the accuracy and consistency of data we send to quality assurance review centers.3. Understand the problems and potential solutions to controversies in quality assurance measures for image fusion, target motion, patient localization, and heterogeneity corrections.
TH‐SAMS‐AUD B‐03: Requirements for Addressing Respiratory Motion in Cooperative Group Clinical Trials (SAM Session)
Authors: Ibbott G 
Published: July 2008

In mid‐2006, the National Cancer Institute (NCI) published updated guidelines for the use of intensity‐modulated radiation therapy (IMRT) on clinical trials, specifically when the target volume included the thoracic region or other areas in which respiratory motion could have a significant effect. In addition to requiring heterogeneity corrections, the NCI now requires that the clinical protocol address the localization and immobilization of both the patient and the tumor. Imaging must be performed in a manner that provides a representation of the target volume without motion artifact. Procedures must be defined to document reproducible daily position of the patient and target. Some form of credentialing is required.The Radiological Physics Center (RPC) has been enlisted to participate in the credentialing process for institutions participating in certain cooperative group trials in which respiratory motion is an issue. To accomplish this, the RPC has constructed several phantoms that mimic the thoracic and abdominal region, and which can be placed on a moving platform to simulate respiratory motion. The combination of phantom and moving platform have been used to evaluate compensation techniques for respiratory motion at several institutions. The techniques employed and the results of these measurements will be described as well as those reported in the literature.Educational Objectives:1. Review the structure supporting cooperative group clinical trials in the US.2. Become familiar with the NCI guidelines for the use of IMRT in clinical trials.3. Learn about the effects of respiratory motion during thoracic treatments.4. Understand the information derived from the RPC's moving anthropomorphic phantoms.This research is supported by grants CA 10953 and 81647 awarded by NCI, DHHS.
TH‐SAMS‐AUD B‐04: Heterogeneity Corrections in Clinical Trials
Authors: Papanikolaou N , Klein E 
Published: July 2008

Clinical trials rely on accurate dose reporting, both for the planning target volumes and organs at risk (OAR). Until recently, clinical trials have not mandated that heterogeneity corrections be applied in dose calculations. Therefore history of prescription and reported doses has been for homogenous water equivalent media. The reticence is attributed to lack of confidence in commercial treatment planning algorithms and in lack of direction as how to change prescriptions when accounting for heterogeneous media. Thorax irradiation is the most challenging example of where corrections and prescription changes are difficult but necessary. Two well reported studies, RTOG‐8808 and RTOG‐9311, required complementary parallel calculations performed. One set was the prescribed and treated homogeneous (water) based calculations, and the other was retrospective heterogeneous CT‐based calculations, but using the homogeneous based MU. The calculations demonstrated major variations in the doses that would have been reported depending if heterogeneity corrections were exclusively used. This was confirmed by dosimetric studies showing the failure of algorithms of the 1990s, particularly in regions of non‐equilibrium. As OAR, particularly lung volume, were often the limiting factor, dose calculations to the lung itself had to be accurate. High energy‐small fields had the largest deviations. The commercial introduction of superposition and Monte Carlo algorithms has remedied the situation by providing accurate calculations, provided they are implemented properly. Simultaneously, publication of AAPM's Report of TG‐65 (Inhomogeneity Corrections) gave direction to physicists as how to work with clinician partners to transition to correction based plans and change prescriptions accordingly.Educational Objectives:1. The history of corrections for clinical trials.2. Progression of algorithms.3. Methods for making the transition to using heterogeneity corrections.
TH‐A‐AUD C‐01: TomoTherapy Commissioning and QA
Authors: Staton R 
Published: July 2008

Helical tomotherapy using the HiArt system can provide highly conformal dose distributions through the implementation of helically delivered intensity modulated radiation therapy (IMRT). The TomoTherapy HiArt system uses a 6 MV linear accelerator mounted on a ring gantry with a simultaneously translating couch. The system also provides image guidance via megavoltage CT. Since this design is significantly different than traditional medical linear accelerators, a unique quality assurance program must be implemented to thoroughly test the HiArt delivery system.This course will provide an overview of the HiArt system components, acceptance testing and commissioning, beam “twinning” for recommissioning of an existing machine to match the TomoTherapy “gold” standard, and basic quality assurance recommendations. The use of ion chamber and diode arrays for patient‐specific delivery QA will also be discussed.Educational Objectives:1. Understand the core concepts of helical tomotherapy.2. Understand the commissioning process for a new HiArt system and the beam “twinning” and recommissioning of an existing HiArt system.3. Understand the machine QA procedures for helical tomotherapy.4. Understand the helical tomotherapy patient‐specific delivery QA process, including the use of ion chamber and diode arrays.Conflict of Interest: Our group holds a research grant from TomoTherapy, Inc.
TH‐B‐AUD A‐01: Accurate Clinical Measurements
Authors: Gibbons J , Seuntjens J 
Published: July 2008

Image‐guided radiation therapy deliveries are becoming increasingly complex and their verification involves clinical measurements in situations that are no longer covered by reference dosimetry protocols or relative dosimetry procedures with simple corrections. In this era of joint imaging‐therapy developments, accurate dosimetry techniques are sometimes trivialized and important effects not understood or ignored. However, clinical measurements increasingly involve reference and relative dosimetry of complex charged particle disequilibrium configurations and their interpretation.This presentation consists of two parts: the first part revisits principles of measurement dosimetry, definitions of detectors and phantoms, reference dosimetry for conventional beams and also discusses some new developments in reference dosimetry of non‐conventional beams. The second part of the presentation concentrates on relative dose measurements with the goal to generate 3D distributions as well as integrated measurements and derived quantities. We conclude with a discussion of relative dosimetry in special cases including the photon build‐up region as well as narrow fields.Educational Objectives:1. To understand the principles of clinical measurement dosimetry.2. To get an overview of detectors and phantoms for reference and relative dosimetry.3. To understand standard clinical reference dosimetry techniques and be exposed to some of the new developments in reference dosimetry in non‐standard beam configurations.4. To get an overview of relative dosimetry techniques for the purpose of 3D dose distributions5. To be aware of the complications of measurements in electronic disequilibrium such as in the photon build‐up and for small photon fields.
TH‐B‐342‐01: X‐Ray Imaging Dose to Patients in the Era of Image‐Guided Radiation Therapy
Authors: Ding G , Price R , Coffey C 
Published: July 2008

Image‐guided radiation therapy (IGRT) makes it possible to locate the treatment target before each radiation dose is delivered while the patient is in the treatment position. It not only minimizes the volume of normal tissue exposed to radiation during treatment but also ensures adequate dose to the treatment target. With the advance of technology, IGRT has emerged as the new paradigm in radiotherapy. The increased clinical availability of new emerging imaging procedures, such as cone beam CT, has resulted in a dramatic growth in its usage and therefore, IGRT procedures may also entail new risk to radiosensitive organs. Unlike diagnostic imaging in radiology, image‐guided procedures are performed much more frequently or daily. Knowledge of radiation dose to patients and accurate dosimetry of radiation dose to organs from each imaging procedure is becoming increasingly important for clinicians as information to consider in making informed decisions regarding the increased dose to radiosensitive organs. This lecture will provide an overview of the commonly used image‐guided rocedures and discuss recent advances in the accurate dosimetry for these imaging procedures, especially for emerging cone beam CT scans. The x‐ray imaging procedures in radiotherapy include megavoltage electronic portal imaging (MV EPI), kilovoltage digital radiography (kV DR), megavoltage cone‐beam CT (MV‐CBCT) and kilovoltage cone‐beam CT (kV‐CBCT).Educational Objectives:1. Understand the commonly used image‐guided procedures in radiation therapy and differences between diagnostic x‐ray imaging and image‐guidance imaging.2. Obtain a prospective view about radiation doses to organs from each image‐guided procedure, especially cone beam CT.3. Learn the large variations between dose to bone (or bone marrow) and dose to soft tissues for x‐rays at kilovoltage energy range.
TH‐SAMS‐AUD B‐01: The Good, The Bad and the Ugly — A Regulatory Update
Authors: Fairobent L , Gilley D , Cameron F , McBurney R 
Published: July 2008

There have been a number of new NRC orders that impact unescorted access to Category 1 and 2 materials such as gamma knife and blood irradiators. Fingerprinting and FBI background checks must now be done. In addition, 10 C.F.R. Part 35 requires that a preceptor statement be signed by an individual that is an Authorized medical Physicist, Radiation Safety Officer, Authorized User or Authorized Nuclear Pharmacist. Recently the Nuclear Regulatory Commission (NRC) has issued findings against signors of preceptor statement for falsifying information. This session will address the liabilities of medical physicists in signing preceptor states, in serving as the “trustworthy and reliable” official for a license in determining unescorted access. It will address differences in non‐agreement states and agreement states.Finally, the AAPM has a policy statement that states: in essence to practice medical physics you must have a masters or Ph.D. and be board certified in one of the disciplines of medical physics. There are four states that required licensure of medical physicists for a number of years. The final talk in this session will look at whether or not having licensure has made a difference in the quality of medical physics practiced and the ramifications of the new Part 35 requirements for training and experience.