bluuebunny/crossref_metadata_2025_split huggingface dataset:
MO‐A‐210A‐01: Update On Fluoroscopy Physics
Authors: Balter S 
Published: April 2010

Radiation usage during fluoroscopically guided interventions can be high enough to warrant careful dosimetry and patient management. Basic compliance with the usual set of local regulatory requirements is sufficient for patient safety in the interventional environments. For example, modern systems meeting all current regulatory dose restrictions are capable of delivering table‐top air kerma rates exceeding 200 mGy/min for normal mode fluoroscopy and 1,500 mGy/min for cinefluorography.Clinical dosimetry during each complex intervention is facilitated by dosimetric instrumentation built into the fluoroscopic system. The Society of Interventional Radiology has published a standard of practice recommending dosimetry for all interventional procedures. In 2008, the ACR published a technical standard for the use of radiation in fluoroscopic procedures. A DICOM Structured Report for detailed reporting of radiation usage in interventional fluoroscopy has been defined, tested and is currently being deployed in clinical systems. The Joint Commission has included fluoroscopic procedures with skin doses exceeding 15 Gy in its list of sentinel events; with the implicit challenge to facilities that they can prove the absence of such occurrences.This course reviews technical elements for a program of patient fluoroscopic radiation safety. ICRU diagnostic dosimetric quantities and their fluoroscopic extensions. Construction, dosimetric features, and performance characteristics of modern fluoroscopes. Extended QA protocols for compliance measurements, system characterization and clinical dosimetry. Dose recording and reporting, including DICOM‐DOSE. The Joint Commission fluoroscopy sentinel event.Learning Objectives1. Understand dosimetric concepts relating to interventional fluoroscopy2. Characterize the dosimetric features and performance of a modern fluoroscope3. Be able to set up a clinical dose recording and reporting policy that will meet clinical and JC requirements.
MO‐B‐BRD‐01: Quality Assurance in Stereotactic Radiosurgery and Fractionated Stereotactic Radiotherapy
Authors: Shepard D , Solberg T 
Published: April 2010

In the 50‐plus years since it was first introduced, stereotactic radiosurgery, high‐dose irradiation of cranial neoplasms delivered in a single fraction, has become a standard of care in the treatment brain tumors, vascular malformations, functional disorders, and pain. Modern radiosurgery can be performed non‐invasively and on an outpatient basis, yet with an extremely high degree of accuracy. Within the past ten years, the field of radiosurgery has seen numerous technological enhancements, including: the development of dedicated devices for stereotactic delivery, the use of relocatable frames to facilitate fractionated delivery, the development of image guided and “frameless” approaches, and the application to extracranial tumor sites. Each of these developments is accompanied by its own challenges in assuring targeting and dosimetric accuracy. In this presentation we review the technologies for stereotactic localization and treatment of cranial targets with particular emphasis on the quality assurance aspects associated with establishing and maintaining a clinical radiosurgery program.Learning Objectives:1. Differentiate how radiation is delivered for Gamma Knife and Linac‐based (conventional and robotic) stereotactic radiosurgery.2. Define the treatment planning parameters for Gamma Knife and Linac‐based stereotactic radiosurgery.3. Discuss measures for assuring accuracy in stereotactic localization and dose delivery for Gamma Knife and Linac‐based stereotactic radiosurgery.
MO‐B‐303A‐01: Digital Mammography Update: Design and Characteristics of Current Systems
Authors: Kanal K 
Published: April 2010

Full Field Digital Mammography (FFDM) systems are fast becoming popular and replacing conventional film‐screen mammography systems. FFDM systems use a digital detector instead of screen‐film to capture the image of the breast. Several FFDM systems based on different digital detector design and materials are currently available. Some systems are characterized as direct conversion detectors and some are based on indirect conversion process. The digital detectors can be characterized by image quality metrics such as detector quantum efficiency (DQE) and modulation transfer function (MTF).In this lecture, the physics and technology of the digital detectors used in FFDM will be discussed as well as the advantages and applications arising due to the availability of these systems will be presented. The most recent commercially available systems will also be discussed.Learning Objectives:1. Understand the physics of digital detector technology2. Understand the image quality metrics such as DQE and MTF3. Recognize that vendors use varying detector technology in FFDM systems4. Appreciate the advantages and disadvantages of digital mammography systems
MO‐D‐BRD‐05: The Proton Beam Therapy Facility at PSI
Authors: Garvey T 
Published: April 2010

The centre for proton therapy at the Paul Scherrer Institute was expanded recently following the commissioning of a new superconducting‐magnet cyclotron (COMET) dedicated to patient treatment. The accelerator was built by ACCEL Instruments GmbH (Varian), based on a design from the National Superconducting Cyclotron Laboratory (Michigan State University). The cyclotron is specified to provide a 500 nano‐Ampere beam of protons at a fixed energy of 250 MeV. The large magnetic field (∼ 3T) required at extraction is provided by the superconducting coils. A high power radio‐frequency system, operating at 72.8 MHz (second harmonic of the cyclotron frequency) provides the required acceleration of protons following their emission from a cold‐cathode ion source. The facility has also been up‐graded with the addition of new gantry (Gantry‐2) for patient treatment and a new beam line dedicated to eye treatments (OPTIS2). A novel feature of COMET is the high beam extraction efficiency (> 80%). This limits component irradiation and facilitates the regular maintenance periods which are an important consideration for any patient treatment center where high reliability and availability are required. We will describe the modes of operation of PROSCAN and, in particular, the spot‐scanning technique used to irradiate tumours. Magnetic elements permit rapid transverse deflection of a pencil beam for two dimensional scanning. An energy “degrader” allows rapid scanning in energy over the range of 70 – 238 MeV. This results in a variable depth of penetration of the beam, thus permitting a complete three dimensional scan. The beamlines which transport protons from COMET towards the two patient gantries and to OPTIS2 will also be discussed. They require sophisticated diagnostics for safe and reliable use of the facility. The various diagnostics include ionization chambers, secondary emission monitors and multi‐leaf Faraday cups. They are used to measure beam current, profile, position, halo and loss. The role of the diagnostics as interlocks for safe operation of the beamlines will also be described.Learning Objectives:1. Understanding the principle of the spot scanning technique.2. Understanding the issues concerning diagnostics for safe beam‐line operation.
MO‐D‐BRB‐01: Study of Systemic and Random Errors On VMAT and IMRT Plan Quality and Deliver Accuracy
Authors: Chen F , Rao M , Ye J , Luan S , Shepard D , Cao D 
Published: April 2010

Purpose: During the delivery of volumetric modulated arc therapy (VMAT), random errors exist in both the MLC leaf positions and the gantry angle. In this work, we investigated the impact of such random errors on VMAT plan quality and delivery accuracy. The impact of system calibration errors was also examined. For comparison purposes, we performed a similar study on step‐and‐shoot IMRT plans. Material and Method: VMAT plans for three treatment sites (prostate, pancreas and head‐&‐neck) were created using a home‐grown arc sequencer. Next, random and systematic leaf position errors were introduced into these plans with the random errors sampled from Gaussian distributions of varying widths ranging from 1 to 3mm. Two types of systematic errors, including MLC bank shifts in the same direction (Type I: leaf gap unchanged) and MLC bank shifts in opposite directions (Type II: leaf gap increase/decrease). The plan quality variations were compared in the Pinnacle3 planning system. Plans with systematic errors were verified using the MatriXX ion chamber array with gamma evaluation criteria of 3%/3mm. Results: The plan degradation observed for VMAT plans was slightly less as compared to that for fixed‐field IMRT plans when random errors up to 3mm to the leaf positions were introduced. With type I systematic errors of 3mm on leaf positions, the average standard deviation of PTV dose increased by 10.2%. This value increased to 18.4% for the corresponding fixed‐field IMRT plans. A larger impact on the IMRT plans was also observed when type II systematic errors were introduced. The above results were confirmed by plan verification measurements with higher gamma passing rates for VMAT plans when systematic errors were applied. Conclusion: The VMAT delivery technique has better tolerance to random and systematic errors in gantry angle and MLC leaf position errors as compared with step‐and‐shoot IMRT.Research supported by Elekta.
MO‐D‐210A‐02: Clinical CT Applications with Photon‐Counting Detectors
Authors: Levinson R 
Published: April 2010

Photon‐counting detectors are now being introduced in medical imaging systems. A major challenge for PC detectors is to enable high count rate operation required for medical imaging. High count rate operation is now available with state‐of‐the art pulse counting electronics. Pulse counting techniques can work together with direct‐conversion sensors enabling additional cost and performance benefits versus indirect‐conversion sensors.PC detectors are easily configurable for multi‐energy acquisitions, enabling dual and triple (k‐edge) imaging techniques. The energy discrimination and binning by PC detectors competes well with the energy separation achieved with dual kVp imaging systems and provides unique performance capabilities for triple/k‐edge imaging.PC detectors have been shown to have negligible levels on electronic noise. The low noise performance enables new scanning techniques and ultimately reduces the radiation dose the patient, an important consideration in the design of X‐ray imaging systems.This lecture will provide an overview on the use of photon‐counting detectors in dual‐energy CT imaging and image quality on clinical CT applications.Learning Objectives:1. Understand the operation of direct‐conversion, photon‐counting detectors2. Application of photon‐counting detectors to multi‐energy CT imaging3. Use of photon counting CT system in a clinical setting
MO‐FF‐A1‐05: Quantitative Radiation Therapy Dosimetry Using Reusable Storage Phosphor KCl:Eu2+
Authors: Han Zhaohui , Driewer Joseph P , Zheng Yuanshui , Low Daniel A , Li H. Harold 
Published: April 2010

Purpose: To investigate the quantitative use of a novel dosimeter for radiation therapy dosimetry. Methods and Materials: Cylindrical dosimeters 7 mm in diameter and 1 mm thick were fabricated. Dosimetric properties were studied with an in‐house optical readout system after irradiation by a linear accelerator. The overall experimental uncertainty was estimated to be within ±2.5%. Results: 1) showed satisfactory radiation hardness. There was no significant change in the stimulation spectra after irradiation up to 200 Gy when compared to a fresh sample, indicating that this material could be reused at least 100 times if 2 Gy per use was assumed, e.g., for a patient‐specific IMRT QA; 2) exhibited supra‐linear response to dose after irradiation from zero cGy to 800 cGy; 3) After x‐ray irradiation the PSL signal decayed with time and eventually reached a plateau (0.1% per hour) after 12 hours, which was significantly better than a commercial CR (computed radiography) plate; 4) The sensitivity of the dosimeter was independent of the dose rate ranging from 15 cGy/min (underneath a MLC) to 1000 cGy/min; 5) The sensitivity showed no energy dependence for either open x‐ray or megavoltage electron fields; 6) Over‐response to low‐energy scattered photons was comparable to radiographic film, e.g., a Kodak EDR2 film. Reduction of dosimeter thickness to tens of microns would minimize the energy dependence. Conclusion: We have demonstrated that dosimeters have many desirable dosimetric characteristics and that has great potential to replace as the primary storage phosphor material for radiation therapy dosimetry. In the future, a large‐area based CR plate created using modern thin film techniques would provide a reusable, quantitative, high‐resolution two‐dimensional dosimeter with minimal energy dependence.This work is supported in part by an NIH grant CA131690.
MO‐FF‐A2‐05: A Novel Stereotactic Radiosurgical Device for the Treatment of Age‐Related Macular Degeneration (AMD)
Authors: Chell E , Firpo M , Bolch W , Lee C , Hanlon J 
Published: April 2010

Purpose: Age‐related Macular Degeneration (AMD) is the leading cause of blindness in people over 65 in the U.S. It is caused by a proliferation of capillaries in the retina and can result in profound and rapid loss of central vision. As a neovascular disease, it has been shown to be susceptible to radiotherapy. Recently, a 100kVp tabletop stereotactic radiosurgical (SRS) device has been developed to deliver highly‐collimated beams of X‐rays to the fovea to treat AMD. This study is an evaluation of that system. Method and Materials: The device delivers a three‐port, 16Gy single fraction dose to the macula. Using a suction‐enabled contact lens assembly (“the I‐Guide”) to stabilize the eye, three 4mm diameter beams of 100kVp x‐rays are delivered to the fovea, directed by a positioning robot. The beams enter the eye through the sclera and avoid the radio‐sensitive lens. The I‐Guide includes reflective fiducials that are monitored by cameras, and the real‐time position of the beam on the retina is calculated from the fiducial positions. Because of uniformity across adult eye populations, a class‐solution treatment plan was implemented using a single parameter (eye length). Software manages treatment time and automatic gating of beam in case of excessive eye motion. A clinical trial is underway. Results: 100kVp proves an optimal energy for ophthalmic radiotherapy. A therapeutic dose to the retina can be delivered with negligible impact to the brain and the scleral entry dose is well‐tolerated. The scatter from the narrow beam is minimal to sensitive structures in the eye. Submillimeter targeting precision was demonstrated in the lab and in the clinic. Submillimeter motion‐management was also demonstrated. Conclusion: The eye‐specific SRS device shows great promise for providing a precise and non‐invasive method of treating AMD.Research sponsored by Oraya Therapeutics.
TU‐A‐BRD‐01: KV and MV Cone‐Beam CT Imaging for Daily Localization: Commissioning, QA, Clinical Use, and Limitations
Authors: Hammoud R , Miften M , Moseley D , Pouliot J 
Published: April 2010

Three‐dimensional conformal radiotherapy (3D‐CRT), intensity‐modulated radiotherapy (IMRT), and stereotactic body radiotherapy (SBRT) allow for the generation of highly conformal dose distributions for patients with tumor volumes wrapped around or adjacent to critical structures. As a consequence of steep dose gradients between the target and organs‐at‐risk, precise localization of the target volume and surrounding normal tissue is essential. However, variations in patient setup and organ motion are limiting factors in the accurate delivery of radiation treatment with a high degree of precision. Recent online image‐guided RT techniques using kilo‐Voltage cone‐beam CT (kV‐CBCT) and Mega‐Voltage CBCT (MV‐CBCT) are now offering the opportunity to overcome these limitations and greatly improve treatment localization accuracy. These IGRT techniques using the latest imaging technologies represent an improvement over traditional techniques such as 2D portal imaging. It allows for the use of volumetric online imaging to account for organ motion and setup variation by providing multiple anatomical views of the patient during the full course of RT treatment. The selection of imaging modality and system to use in support of a treatment protocol is often a compromise between image quality, efficiency, availability, and dose. The objective of this educational session is to review the current kV‐CBCT and MV‐CBCT imaging systems and their evolution for daily localization including1. Commissioning, image quality, dose, registration process, and acquisition modes2. Clinical integration3. QA, stability over time, and downtime4. Standard clinical applications5. Novel clinical applications6. Technology evolution and future directions
TU‐A‐303A‐01: C‐Arm Cone‐Beam CT: Principles and Applications
Authors: Siewerdsen J , Chen G 
Published: April 2010

This Continuing Education session surveys the principles of 3D reconstruction, image quality, radiation dose, and applications of C‐arm cone‐beam CT. The availability of such systems has grown over the past several years, with applications including neurovascular and cardiovascular imaging in image‐guided interventions and surgery. Some systems employ conventional x‐ray image intensifiers, with corresponding limitations in image quality (i.e., imaging of high‐contrast structures only). More recent systems incorporating a flat‐panel detector in the imaging chain demonstrate increased field of view, higher 3D spatial resolution, improved noise characteristics, and the capability to visualize soft‐tissue structures. The basic principles of cone‐beam CT image reconstruction are reviewed (Feldkamp algorithm) in comparison to conventional fan‐beam filtered backprojection. The influence of image artifacts most relevant to C‐arm cone‐beam CT are reviewed — in particular, x‐ray scatter, object truncation, and the “cone‐beam” artifact. The factors governing 3D image quality are explained, with emphasis on the ability to image soft‐tissue structures, and issues of radiation dose characterization are discussed. The spectrum of various C‐arm cone‐beam CT systems is discussed in relation to primary applications in image‐guided interventions. Emphasis throughout is in regard to factors most relevant to the practicing medical physicists.Learning Objectives: Attendees will gain practical understanding of:1. Basic principles of 3D cone‐beam CT reconstruction2. Image quality and artifacts most relevant to cone‐beam CT3. Spectrum of systems and applications of C‐arm cone‐beam CTI
TU‐A‐213A‐01: CT Clinical Perspective: Challenges and the Impact of Future Technology Developments
Authors: Vannier M 
Published: April 2010

Computed tomography is not the most frequent radiologic imaging procedure, but is arguably the most important in terms of clinical impact. CT is used extensively for emergencies, cardiovascular, pulmonary, gastrointestinal, endocrine, neurological, orthopedic and other applications — often as the first and only imaging procedure needed for diagnosis. The chances are very high that a patient will have a CT scan in the emergency department, as an outpatient or as an inpatient for a multitude of indications — pain, trauma, suspected infection or malignancy, and frequently to investigate symptoms such as pain, or to answer a question raised by another abnormal test, such as an EKG abnormality or ultrasound finding.Despite the universality of CT in hospitals and clinics as well as free‐standing imaging centers, the technology continues to evolve with greater coverage, faster acquisition and multienergy sources or detectors. Multimodality scanners based on CT incorporate PET/SPECT and in the future, MRI to combine morphologic and functional imaging.The most demanding imaging applications are cardiovascular, where complex motion and small morphologic features coexist, so imaging methods that are very satisfactory elsewhere in the body may not be successful. Clinical CT scanning consists of administering toxic materials, e.g., contrast media, often monitoring the EKG and illuminating the body with high brightness x‐rays. Larger area detectors and higher acquisition rates are welcome improvements, but don't solve all of the problems encountered with scan variability due to respiratory, random body, and cardiac motion, especially in a spectrum of patients from infant to massively obese adult sizes (< 1 kg to 250 kg or more). The challenges and pitfalls in CT and multimodality imaging will be delineated and evaluated relative to current and future technology.Learning Objectives:1. The role of x‐ray computed tomography (CT) in clinical medicine is central to diagnostic radiology and its functions as a hospital‐based department and service to outpatients.2. CT technology developments, including wide area coverage multirow detector scanners, dual energy acquisition systems, visualization and post‐processing introduce changes in CT applications and utilization.3. The limitations of a single modality, such as CT, can be overcome by integrating complementary instrumentation, especially PET/SPECT, MRI and others (such as ultrasound and fluoroscopy) to provide simultaneous morphologic and functional imaging capabilities.
TU‐A‐213A‐02: Quantitative PET/CT Imaging for Drug Discovery, Clinical Trials, and Individual Response to Therapy
Authors: Kinahan P 
Published: April 2010

Recent publications have established quantitative measures of tracer uptake used in positron emission tomography (PET) imaging as a predictor of patient outcome including pathologic response, disease‐free survival and overall survival in single institution imaging and therapy trials. There is increasing interest in using PET as a biomarker to evaluate response to therapy and possibly as an endpoint for cancer therapeutic response in multi‐center trials. However, several sources of variance and inherent in quantifying PET tracer uptake should understood and determined in order to ascertain the significance of differences in serial measurements and aid estimation of expected variances during clinical trial design.In this presentation we will review the major sources of bias and variability from the patient, imaging protocol, data processing, and image analysis. We will also briefly discuss artifacts from PET and PET/CT imaging.The presentation will conclude with a review of efforts to address complexities that arise from combining quantitative PET/CT data from multiple patients at multiple sites. Research partially supported by NCI Contract 24XS036‐004 (RIDER).