bluuebunny/crossref_metadata_2025_split huggingface dataset:
WE‐D‐M100F‐03: MRI/MRS for Chemo/radiation Therapy Response Assessment
Authors: Jackson E 
Published: July 2007

Several functional MR techniques, including dynamic contrast agent enhanced MRI (DCE‐MRI), dynamic susceptibility change MRI (DSC‐MRI), diffusion MRI, blood oxygen level dependent (BOLD) MRI, and in vivo spectroscopy, have been proposed and utilized to monitor the effects of conventional and targeted therapies in a longitudinal, non‐invasive manner. This symposium session will briefly review the physical basis of each of these techniques and then will review representative pre‐clinical and clinical trial findings obtained using these methodologies to assess response to treatment by radiation and/or chemotherapy.Objectives:1. Review the physical basis of DCE‐MRI, DSC‐MRI, diffusion MRI, BOLD MRI, and MR spectroscopy techniques.2. Review representative applications of the techniques described above to pre‐clinical and clinical trial applications for early assessment of radiation therapy, both as a single regimen as well as in combination with chemotherapeutic and/or targeted therapies.
WE‐D‐BRB‐01: Support for Staffing and Assuring Quality in Radiation Oncology
Authors: Mills M , Hogstrom K , Dunscombe P 
Published: July 2007

Standards for commissioning and quality control of radiation therapy equipment have traditionally been established through the consensus of “experts”. The recently implemented Canadian approach to standards (medphys.ca) has broadened the expert panel to include the entire Canadian medical physics community through web‐based consultation. This process and the standards so developed will be discussed. A limitation is that while such standards developed to date in Canada and in many other jurisdictions undoubtedly have made major contributions to the safety and quality of radiation therapy, they could not be described as being evidence based. An approach to “evidence based” commissioning of a treatment planning system, in which the Equivalent Uniform Doses of targets and organs at risk are used as outcome surrogates, will be discussed. The resulting Quality Control Standards, whether using the novel Canadian approach or the more traditional AAPM Task Group approach, require a determinable amount of time that must be performed by medical physicists. Staffing at appropriate levels to accomplish these tasks is the focus of all activities in medical physics. Proper staffing is therefore crucial to patient care, and necessary to meet regulatory requirements. The results from the Abt study of medical physicist work values for radiation oncology physics services: round III may be used to justify personnel and defend staffing to administration for a number of venues of practice. A work model is created to allow the medical physicist to defend QMP work based on both routine and special procedures service mix. The model may be used to develop a cost‐justification report for setting charges for radiation oncology physics services.Objectives:1. Understand alternative options to develop Quality Control Standards for Radiation Oncology Physics.2. Understand what new information will be provided in the Abt III study.3. Understand how to use the Abt studies to justify medical physicist work and staffing.
WE‐D‐L100E‐01: Cone Beam CT Workshop
Authors: Fahrig R , Siewerdsen J , Jaffray D , Boone J 
Published: July 2007

The development of practical large field‐of‐view flat panel x‐ray detectors has lead to an explosion in cone‐beam computed tomography (CT) applications. In this workshop, a number of different clinical applications for cone‐beam CT will be described. Methodologies for addressing issues such as x‐ray scatter, detector lag, and limited field‐of‐view or angular coverage will also be discussed.C‐arm fluoroscopic systems have been used for image guidance in the operating room for many years. With the advent of flat panel‐based C‐arm systems, the availability of portable, operating room‐based computed tomography systems exists. The three dimensional characteristics of CT will likely improve surgical outcomes involving surgical device implantation. The development of a portable C‐arm‐based CT system, for use in the operating theater as well as in other clinical settings, will be discussed.Angiographic suites are designed to optimize vascular imaging geometry. Flat panel‐based angiography suites have undergone modifications to allow CT imaging for some specific vascular imaging applications. These systems are also capable of performance in orthopedic applications. The use of such systems in a number of clinical applications will be described, and corrections methods for x‐ray scatter and detector lag will also be presented.The use of image guidance in radiation therapy applications has skyrocketed, and in many clinical radiation therapy systems, system‐mounted cone‐beam CT systems are available for use for guiding RT delivery. The use of cone‐beam CT for radiation therapy applications will be described, and some of the challenges and limitations of this technology will be discussed.Overall, a sampling of cone‐beam CT applications will be presented in this workshop. The overall flexibility of cone‐beam CT systems to accommodate the wide range of applications described is a testimony to the long term clinical potential of cone‐beam CT systems. This workshop will also describe some of the compromises and limitations which are required when cone‐beam CT geometry is utilized.
WE‐E‐L100F‐01: After the Discovery: Roentgen's Investigation of “Eine Neue Art Von Strahlen”
Authors: Sprawls P 
Published: July 2007

Immediately following Roentgen's discovery of a “Eine neue Art von Strahlen” (new kind of rays), or x‐rays as he later named them, he conducted extensive experiments to determine their properties and possible applications. In this session we follow his thoughts as reported in his three landmark publications and observe many of his experiments through visual recreations of the laboratory activities. We find that he, in investigating this new and different radiation, conceived and used many of the same instruments and techniques used today. Within a few months of intensive research he had discovered, evaluated, and documented essentially every property of x‐radiation.Educational Objectives:1. Reflect on Roentgen's thoughts and ideas as he leads across one of the major frontiers in science and medicine.2. Observe the experiments that demonstrate many characteristics of a new kind of radiation.3. Appreciate the creative techniques and scientific approach of Roentgen as a model for effective research.
WE‐E‐M100J‐02: Functional Imaging of the Lungs for Treatment Planning
Authors: Guerrero T 
Published: July 2007

Delivery of radiotherapy through hypoperfused pulmonary regions for lung cancer treatment has been shown to result in less pulmonary injury in a single prospective trial. This finding suggests a strategy for image‐guided radiotherapy utilizing physiological images in radiotherapy treatment planning for image guidance to avoid the irradiation of highly functional regions and minimize the injury and/or function loss following thoracic radiotherapy. Patients may have inhomogeneous lung function distribution due to tumor invasion of the airway and vascular structures and/or preexisting pulmonary diseases. Imaging studies have found the prevalence of these hypoperfused regions adjacent to the primary tumor from 43 to 74% in non‐small cell lung cancer cases. However, the current thoracic treatment planning practice has been primarily based on using anatomical information from the treatment planning computed tomography (CT). Therefore, the non‐uniform distribution of regional function of normal lung tissue has not been considered in the process of treatment planning. Imaging modalities that have been reported in treatment planning studies to provide image guidance to identify the highly functional regions include single photon emission computed tomography perfusion, hyperpolarized gas magnetic resonance ventilation, and 4D CT derived ventilation imaging. No prospective studies demonstrating improvement in outcome using these modalities for functional image‐guided radiotherapy have yet been reported. Strategies to incorporate functional image guidance include identification of highly functional regions by an expert for avoidance, automated segmentation of pulmonary regions with the highest function for avoidance, and optimization of functional metrics including the dose function histogram.This lecture will provide an overview of the physiologic origins of the functional imaging methods, post‐acquisition processing, and strategies to integrated functional imaging into thoracic treatment planning.Educational Objectives:1. Understand clinical basis for the use of functional imaging for treatment planning.2. Survey the functional imaging modalities which may be utilized for image‐guidance.3. Review strategies to integrated functional imaging into thoracic treatment planning.
WE‐E‐AUD‐01: Artifact Free EBT Film Scanner for Radiotherapy Dosimetry
Authors: Ranade M , DuBose R , Li J , Kozelka J , Simon W , Dempsey J 
Published: July 2007

Purpose: To build a high resolution, accurate, 2D optical densitometer that eliminates scanner‐film artifacts commonly observed in radiochromic film dosimetry. Method and Materials: An optical densitometer was built using a stationary light source and detector with a moving film holder attached to a high precision computerized X‐Y stage. The light source was a red LED (633nm), to conform to EBT film absorption peak. Two silicon photo‐detectors were used to measure incident and transmitted light. The LED output was focused to a sub‐millimeter spotsize at the film. Data acquisition was performed with a 16‐bit A/D card in conjunction with commercial software. The densitometer was used with radiographic EDR2 and radiochromic EBT films. Sensiometric curves and three IMRT field scans were acquired with a resolution of 1mm. The results were compared with the MapCHECK diode array measurement under identical geometry. The EBT film was rotated by 90 degrees and rescanned to record orientation effects. Results: A spotsize of 0.8mm was measured at the film using the half razor technique. The EBT film rotated by 90 degrees showed no orientation effect. From the absolute comparison mode of the MapCHECK analysis software, the average passing rates with 3%/3mm criteria were 97.5% for EBT films and 96.6% for EDR2 films. The main difference between EBT and EDR2 measurements were in low dose areas, with EDR2 readings higher. This is most likely due to over response of the radiographic film to scatter radiation. No artifacts were observed in the scanned films. A scan of 15×15cm took 20 minutes to acquire. Conclusion: The LED densitometer provides accurate film dosimetry with 1mm or better resolution. It eliminates the orientation dependence of EBT film dosimetry. The IMRT results compared well with Mapcheck measurements.This work was supported in part by NCI grant R01‐CA‐100636 and Contract No. HHSN261200522014C.
TH‐C‐M100E‐05: Fabricating a Customized Gating System for Large Bore AcQSim CT Scanner
Authors: Sohn J W , Barritt B , Daher G , Turnbull J P , Park S B , Chankong V , Monroe J I , Klahr P 
Published: July 2007

Purpose: A customized gating system was developed for a large bore CT scanner to produce gated images for use with an active breathing control (ABC) system. Operator triggering following a breath hold is replaced by an electronic gating signal from a bellows. A breathing phantom was constructed and imaged to insure accurate gating. Methods and Materials: A bellows strap wraps around the patient to monitor breathing during CT scans. A universal serial port (USB) cable provides power to the bellows sensor via the circuit box. Bellows signals route to the computer from the circuit box via another USB cable. Operators can set a threshold point in the breathing cycle that corresponds to an ABC breath‐hold to trigger the CT scanner. Software generated signals gate the CT through the circuit box. Unique to this system is an option to scan continuously while the patient is holding a breath, in contrast to commercial gated‐CT systems which take one image per breathing cycle. A breathing phantom was created using a computer programmed actuator, step‐motor, and off‐set ball. A sine wave modeled on human breathing was fed to the actuator. The moving range was 2.10 cm anterior‐posterior and 1.05 cm in lateral direction. The diameter and motion period was 6.4 cm and 5.54 sec. Phantom images taken were: stationary non‐gated, moving gated, and three un‐gated while moving. All image sets were analyzed with the Pinnacle planning system. Volumes generated from contours where used as a metric to determine imaging accuracy. Results: Target volumes of stationary and gated imaging were 146.8 and 145.5cm3, respectively (1% agreement). However, the discrepancies between stationary and all three un‐gated scans ranged from 4.84 to 5.45% with significant shape distortion.Conclusions: We successfully created a custom gating system for a large‐bore CT simulator.
TH‐C‐M100E‐08: Evaluation of Multiple‐Isocenter IMRT Planning Technique for Field Matching with Limited Collimator Field Size
Authors: Fallon K , Xiao Y , Machtay M , Galvin J 
Published: July 2007

Purpose: The Elekta Beam Modulator with fully integrated miniMLC has the precision suited for the treatment of smaller tumors. However, the maximum collimator length in the inf/sup direction is 16 cm when most of the head and neck target sizes have a larger dimension. This study used a multi‐isocenter IMRT planning technique with overlapping fields generated using inverse planning. Measurements have been taken to evaluate plans in terms of volume dose and delivery accuracy. The total monitor units for this technique were compared with a standard IMRT plan. Methods and Materials: Ten patients were planned with multiple beam arrangements; eight beam directions for the upper tumor volume without the supraclav and three to four beam arrangements for the lower tumor volume and supraclav. Treatment planning was performed on a CMS/XiO workstation. Treatment fields were delivered on a flat acrylic phantom containing EDR2 film. Isodose distributions were exported from XiO and compared to the measured data using Omni‐Pro software. Results and Conclusions: Multi‐isocenter techniques provide good coverage to the tumor volume while sparing organs at risk. Film distributions show that XiO does not model the effective tongue and groove that is evident in the film measurement. The magnitude of the tongue‐and‐groove dose decrease is on the order of up to 10%. An analysis of the gamma values shows that even with this discrepancy the agreements between plan and measurement were acceptable. The plans are not significantly degraded with small table inaccuracies on the order of 2mm. The total monitor units for multi‐centered plan increased 20% compared to single isocenter delivery.IMRT planning techniques using two or more isocenters for this collimator show clinically acceptable results when splitting the geometry.
TH‐D‐M100J‐07: CT Image Registration in Sinogram Space
Authors: Mao W , Li T , Wink N , Xing L 
Published: July 2007

Purpose: Object displacement in a CT scan is generally reflected in CT projection data or sinogram. Conventional registrations in the image space are often adversely influenced by the reconstruction‐induced artifacts. A direct sinogram‐based registration has been studied. Method and Materials: It is found that a rigid motion only affects the projection angle and radial distance of the CT projections instead of the intensity. Simple equations have been successfully deduced.A simulated 2D phantom model was adopted and modified to test the algorithm. A physical head phantom was scanned using a kV cone beam scanner. Fan beam sinograms were then generated for the central axial plane.Upon random 2D rigid motions, registrations were carried out in the sinogram space. For every possible motion, the relevant sinogram was generated according to the discovered relationship and compared with the reference sinogram, as a result, the most likely motion was obtained. Results: Simulated and experimental results demonstrate that the new registration technique works well for registration of rigid motion in parallel beam sampling and fan beam sampling CT scans. The images were reconstructed from the registered sinograms and the spatial accuracy of this new registration was better than 2 mm.It is also found that this sinogram registration couldn't be affected by the metal filling, the truncation, or uncompleted projection set. This makes it appealing for various applications in image guided radiation therapy (IGRT). Conclusions: The direct relationships between the object motion and the change of CT projection data (sinogram) were studied and this knowledge was successfully applied to a novel algorithm for sonogram‐based registration. Calculated and experimental results demonstrate that the new registration technique works well particularly when registering images with metal or truncation artifacts.
A Novel Alphavirus Vaccine Encoding Prostate-Specific Membrane Antigen Elicits Potent Cellular and Humoral Immune Responses
Authors: Durso Robert J. , Andjelic Sofija , Gardner Jason P. , Margitich Dennis J. , Donovan Gerald P. , Arrigale Robert R. , Wang Xinning , Maughan Maureen F. , Talarico Todd L. , Olmsted Robert A. , Heston Warren D.W. , Maddon Paul J. , Olson William C. 
Published: July 2007

AbstractPurpose: Prostate-specific membrane antigen (PSMA) is an attractive target for active immunotherapy. Alphavirus vaccines have shown promise in eliciting immunity to tumor antigens. This study investigated the immunogenicity of alphavirus vaccine replicon particles (VRP) that encode PSMA (PSMA-VRP).Experimental Design: Cells were infected with PSMA-VRP and evaluated for PSMA expression and folate hydrolase activity. Mice were immunized s.c. with PSMA-VRP or purified PSMA protein. Sera, splenocytes, and purified T cells were evaluated for the magnitude, durability, and epitope specificity of the anti-PSMA response. Antibodies were measured by flow cytometry, and cellular responses were measured by IFN-γ enzyme-linked immunospot and chromium release assays. Cellular responses in BALB/c and C57BL/6 mice were mapped using overlapping 15-mer PSMA peptides. A Good Laboratory Practice–compliant toxicology study was conducted in rabbits.Results: PSMA-VRP directed high-level expression of active PSMA. Robust T-cell and B-cell responses were elicited by a single injection of 2 × 105 infectious units, and responses were boosted following repeat immunizations. Anti-PSMA responses were detected following three immunizations with 102 infectious units and increased with increasing dose. PSMA-VRP was more immunogenic than adjuvanted PSMA protein. Responses to PSMA-VRP were characterized by Th-1 cytokines, potent CTL activity, and IgG2a/IgG2b antibodies. T-cell responses in BALB/c and C57BL/6 mice were directed toward different PSMA peptides. Immunogenic doses of PSMA-VRP were well tolerated in mice and rabbits.Conclusions: PSMA-VRP elicited potent cellular and humoral immunity in mice, and specific anti-PSMA responses were boosted on repeat dosing. PSMA-VRP represents a promising approach for immunotherapy of prostate cancer.
Elevated Peroxiredoxin 1, but not NF-E2–Related Factor 2, Is an Independent Prognostic Factor for Disease Recurrence and Reduced Survival in Stage I Non–Small Cell Lung Cancer
Authors: Kim Joo-Heon , Bogner Paul N. , Ramnath Nithya , Park Yoorim , Yu Jihnhee , Park Young-Mee 
Published: July 2007

Abstract
Purpose: Lung cancer is the leading cause of cancer death with chance of survival restricted to a subset of non–small cell lung cancer (NSCLC) patients able to undergo surgical resection. However, the recurrence rate of NSCLC after surgery remains high with few prognostic indicators of clinical outcome. Peroxiredoxin1 (Prx1) is shown to be elevated in various cancers and confers an aggressive survival phenotype. We recently cloned the prx1 promoter and found that NF-E2–related factor 2 (Nrf2) is a key transcription factor for prx1 up-regulation. Previous studies suggest that Nrf2 may be constitutively activated in NSCLC. Based on the above information, we investigated whether Prx1 and/or Nrf2 levels have prognostic significance in stage I NSCLC.
Methods and Results: Immunohistochemical expression of Prx1 and Nrf2 was evaluated in paraffin-embedded tissues from 90 patients who underwent a curative surgical resection. Increased expression of cytosolic Prx1 (66.7%) and nuclear Nrf2 (61.8%) was observed in this series. Prx1 elevation, but not Nrf2, correlated with reduced recurrence-free survival and overall survival on univariate (P = 0.01 and P = 0.03) and multivariate (P = 0.003 and P = 0.005) analyses.
Conclusion: This is the first study to test the prognostic significance of Prx1 and Nrf2 in human cancers. Our results show that Prx1 expression status predicts for recurrence and shorter survival in stage I NSCLC after surgery. Considering the possible role of Prx1 and Nrf2 in radioresistance/chemoresistance, it warrants future investigation to evaluate whether elevated Prx1 and/or Nrf2 levels are predictive of treatment response in advanced lung cancer and other malignancies.
Statistical Error Decomposition of Regional-Scale Climatological Precipitation Estimates from the Tropical Rainfall Measuring Mission (TRMM)
Authors: Fisher Brad L. 
Published: July 2007

Abstract
Monthly rainfall estimates inferred from the NASA Tropical Rainfall Measuring Mission (TRMM) satellite contain errors due to discrete temporal sampling and remote spaceborne rain retrievals. This paper develops a regional-scale error model that uses the rain information in the ground data to disentangle the sampling and retrieval errors in the satellite estimate statistically. The proposed method computes a mean rain rate from monthly rainfall statistics for each TRMM rain sensor by subsampling high-resolution ground-based rain data at satellite overpass times. This additional rain-subsampled parameter plays an essential role in the statistical decomposition of the total error distribution into its sampling and retrieval error components. Using the statistical formalism developed in this study, an error analysis was performed on 5 yr of monthly rain estimates produced by the TRMM Microwave Imager (TMI) and precipitation radar (PR) rain sensors aboard TRMM over a quasi 2° × 2° region of the TRMM ground validation (GV) site at Melbourne, Florida. Annual retrieval and sampling error statistics were computed for the TMI and PR using monthly rainfall estimates derived from two independent ground-based sensors: a regional rain gauge network and the Next-Generation Weather Radar (NEXRAD). Subsampled ground-based rainfall estimates produced for the radar and the gauges were highly correlated with the TMI and PR rainfall estimates, and both GV sensors produced relatively consistent error estimates. The PR-to-TMI sampling error ratio was equal to about 1.3, which was in close agreement with prelaunch predications, and the TMI-to-PR retrieval error ratio was about 2.0. For the TMI, a seasonally alternating rainfall bias was also observed that was negative during winter and positive during summer.