bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐GG‐J‐118: Geometrically Targeted Radiation Enhancer Using Semiconductive Nanoparticles
Authors: Sheng K , Wang L , Rzigalinski B , Read P , Larner J , Yang W 
Published: August 2010

Purposes: Photo‐emitting semiconductive nanoparticles conjugated with photosensitizer molecules are a promising enhancer for radiation therapy. The purposes are to study toxicity, biodistribution, and in vivo efficacy of the nano‐conjugate. Methods and materials: The toxicity of the conjugate was evaluated by propidium iodide uptake of both 3T3 fibroblast and normal organotypic brain cells 5 to 10 days post exposure to drug with a concentration from 24fM to 24μM. H460 cancer cells were used as the xenograft model in nude mice and the tumors were grown for 1 week. To investigate the biodistribution, tail vein injection of 42nM QDs with or without conjugated folic acid were administered in 2 doses at 24 hours and 16 hours prior to dissection. Tissue samples were taken from the liver, the kidney and the tumor. To measure the efficacy, QDs conjugated with Photofrin and (or) folic acid were injected with the same total dose. 8 Gy of radiation were delivered in a single fraction. The tumor size was measured twice a week and compared with the control group. Results: There was no detectable toxicity for QD concentration up to 24 pM. Cell death was observed at 24nM but remained at a very low level. Less than 2% positively labeled tumor cells were observed under fluorescent microscope with QDs alone. However, the percentage of positively labeled cells increased 38 folds with folate. The in vivo efficacy study is consistent with the biodistribution, with no detectable tumor growth delay from QD/Photofrin alone but a significant growth delay of 3 days (p=0.05) was observed with QDs conjugated to both Photofrin and folate.Conclusions: Toxicity of the conjugate to normal tissue is low at the level for radiation enhancement. Effectiveness is demonstrated for the first time on an animal model. Methods of drug delivery play critical roles in the efficacy.
SU‐GG‐J‐119: Induction of Plasmonic Heating Inside Breast Tumor Phantom Using Gold Nanorods and Near‐Infrared Laser
Authors: Cho S , Siddiqi A , Manohar N 
Published: August 2010

Purpose: To demonstrate and quantify gold nanorods (GNRs)‐induced plasmonic heating inside breast tumor phantom during near‐infrared (NIR) laser illumination. Method and Materials: GNRs were fabricated using published procedures. Two types of breast gel phantoms were fabricated. The first phantom was nearly water‐equivalent as it was fabricated using 1.5% agar gel (98.5% water). The second phantom, on the other hand, was fabricated using a more turbid intralipid‐based gel (2% agar, 2% intralipid, and 96% water). Both phantoms contained an identical GNR‐filled cavity with 4 mm inner diameter. The cavity was filled with approximately 0.1 weight percent GNRs and located at the center of a quadrant of hemispherical phantom at 2.5 cm depth measured from the base of the phantom. Both phantoms were illuminated with an 808 nm NIR laser at 1 W power under the identical geometry. Thermocouples were used to measure the temperature changes within the cavity and surrounding medium. Results: There was significant difference between the two gel phantoms in terms of achievable temperature rise within a GNR‐filled cavity. For a 60 second illumination, the cavity inside an agar‐based gel phantom was heated up to 15°C above the background temperature, while there was a temperature change of only about 1.5°C within the cavity inside an intralipid‐based gel phantom. Conclusion: The current results suggest tumors inside breast tissue with high water content may be easily heated up to a few degrees above the surrounding body temperature within a short time interval (e.g., on the order of 10 seconds) without much difficulty. According to the current results, however, it might be difficult to achieve such a temperature change for tumors inside breast tissue similar to intralipid‐based gel in terms of its optical property.This work has been supported by the US Department of Defense, Breast Cancer Research Program, Concept Award, W81XWH‐08‐1‐0686.
SU‐GG‐T‐522: Investigation of Intracranial Localization for SRS and SRT Using MV‐CBCT
Authors: Johnson M , Gayou O 
Published: August 2010

Purpose: To investigate the accuracy and precision of Mega‐Voltage Cone Beam Computed Tomography (MV‐CBCT) localization for intracranial stereotactic treatment deliveries. Method and Materials: A Rando head phantom containing a metal ball bearing (BB) was mounted with a head frame. A treatment plan targeting the BB was generated and three localization methods were compared. The first, was the standard technique using laser micro‐alignment to the isocenter projected onto target positioning sheets. Second, a standard MV‐CBCT was acquired, using skull based registration with the treatment planning CT and millimeter precision correction using the motorized treatment couch. For the third, a micro‐adjustment of the head frame position using a Vernier scale was used to apply the MV‐CBCT correction with a 0.1 mm accuracy. After localization with each method was achieved, a series of 1.0 × 1.0 cm fields from gantry angles 0, 90, 180 and 270 degrees was used to asses target alignment by measuring the BB position relative to the beam central axis. Results: The standard localization technique resulted in an average displacement of the BB with respect to the beam central axis of 1.2 ± 0.1 mm. Skull‐based localization with MV‐CBCT using millimeter precision couch offsets resulted in a displacement of the BB with respect to the beam central axis of 2.3 mm. Localization with MV‐CBCT and micro‐adjustment resulted in a displacement of the BB with respect to the beam central axis of 1.2 ± 0.2 mm. Conclusion: After modifications were applied to the MV‐CBCT localization technique, accuracy was as good as the standard approach for head frame cases. When MV‐CBCT localization is applied to a frameless case, the anatomy‐based alignment eliminates the variability of interfraction patient positioning within the immobilizing mask.Conflict of Interest: Research partially funded by Siemens Medical Solutions.
SU‐GG‐T‐565: Radiotherapy of Patients with Bilateral Hip Replacement Using Volumetric Modulated Arc Therapy (RapidArc)
Authors: Aydogan B , Yeginer M 
Published: August 2010

Purpose: To investigate a volumetric modulated arc therapy (RapidArc)‐based scheme to improve dose homogeneity, target coverage and organ at risk sparing in prostate cancer patients with hip replacement. Method and Materials: RapidArc (RA) treatment plans for previously treated 7 prostate patients with hip replacement are generated and compared with the IMRT plans used in their treatments. The total prescription dose of 50.4 Gy is delivered in 28 fractions of 1.8 Gy/fraction. Organs at risk (OARs) include bladder, rectum, small bowel and femoral heads. Magnetic Resonance images are co‐registered with computed tomography images to correctly delineate prostate volume. Inhomogeneity correction is turned off for both IMRT and RA plans. Single (sRA) and double (dRA) RapidArc plans are generated and compared with the seven‐field IMRT plans. Two 60‐degree lateral sectors between 60–120 degrees and 240–300 degrees were skipped to avoid irradiation through the high Z materials in the hip. All plans are optimized and normalized to provide a minimum of 94% target coverage with the prescription dose. Results: The maximum PTV doses are 54.5Gy (IMRT), 57.1Gy (sRA) and 52.8Gy (dRA). Overall, dRA performed better in PTV coverage, dose homogeneity and the OAR sparing than did sRA and IMRT. For instance, V100 for rectum is 13%, 30% and 50% with dRA, IMRT and sRA. Homogeneity index (HI) is 103.5%, 106.7% and 109% for dRA, IMRT and sRA, respectively. The total monitor unit is 968 MU (IMRT), 429 MU (sRA) and 518 MU (dRA). Conclusion: RapidArc with one and two arcs is investigated in prostate cancer patients with hip replacement. Only RapidArc with two arcs (dRA) showed some improvements in OAR and healthy tissue sparing, target coverage and dose homogeneity with respect to IMRT. The treatment delivery is more efficient with single arc RapidArc.Conflict of Interest: Sponsored by Varian Medical Systems, Inc.
MO‐A‐201C‐01: Modern US Equipment and US Physics
Authors: Fowlkes B 
Published: August 2010

Diagnostic ultrasound imaging has advance substantially over the past 25 years and this has been accelerated by the progressive move toward digital systems. Modern ultrasound systems rely heavily on multi‐element array transducers, image reconstruction, and signal processing to produce the clinical images seen today. In addition, there has been a significant effort to make ultrasound more portable and less expensive while trying to maintain image quality and performance. Those involved in the operation and evaluation of ultrasound systems need to understand the technology and approaches being used in ultrasound imaging today.This lecture will provide the background understanding of ultrasound physics and its application in imaging systems and the evolution of imaging toward the modern digital devices being used today.Learning Objectives:1. Understand fundamental physics and operation of b‐mode and Doppler.2. Understand recent advances in signal processing including harmonic imaging, coded excitation, automated optimization methods, compound imaging and speckle reduction.3. Understand the methods for image improvements by the processing methods used in ultrasound imaging.
MO‐A‐202‐01: Patient Dose and the Modern Angiographic System
Authors: Schueler B 
Published: August 2010

Recently, the FDA announced a new initiative to promote the safe use of fluoroscopy and CT devices which includes enhancement of radiation dose measurement, display and recording. This initiative has resulted from increased scrutiny of patient radiation exposure from medical procedures and notable incidents of deterministic effects resulting from high exposure levels. In the present environment, it is critical that medical physicists have a clear understanding of radiation dose quantities and measurement methods. This course will focus on radiation dose in fluoroscopic equipment.Quality control testing of fluoroscopy systems should include measurement of patient dose to ensure dose rates are appropriate and meet regulatory requirements and verify that displayed dose values are accurate. The medical physicist should also understand the variation in dose rate and image quality with respect to spectral filtration, kVp, pulse rate and patient thickness. This understanding is necessary to ensure appropriate dose settings are available to the operator. Education of fluoroscopy operators in how to optimize image quality and minimize patient dose is another important role for the medical physicist.Learning Objectives:1. Review fluoroscopic dose quantities.2. Understand the operation of kerma‐area‐product meters.3. Learn how to verify the accuracy of displayed dose values, including recommended quality control testing frequencies and control limits.4. Understand how to measure fluoroscopy and fluorography phantom entrance air kerma for comparison to expected reference standards and regulatory maximum limits.5. Review equipment factors and operator factors that affect patient fluoroscopy dose and image quality optimization.
MO‐B‐202‐01: Status/Impact of Lowering the Annual Limit from 5‐2 Rem
Authors: Cool D 
Published: August 2010

Options to Revise the Nuclear Regulatory Commission's Radiation Protection RegulationsThe Nuclear Regulatory Commission (NRC) is in the process of engaging stakeholders on issues associated with possible changes to the radiation protection regulations contained in 10 CFR Part 20, and other parts of the NRC regulations, to increase alignment with recent recommendations of the International Commission on Radiological Protection. The Commission is particularly seeking to explore implications, as appropriate and where scientifically justified, of greater alignment with ICRP Publication 103. Other information from national and international sources are also being considered. Given that the NRC regulations provide adequate protection, the discussion has been focusing on discerning the benefits and burdens associated with revising the radiation protection regulatory framework. The NRC staff is to provide recommendations to the Commission in late 2011.The staff has identified a number of key issues for ongoing discussion, as a result of its initial analysis, and as a result of consultations with stakeholders during 2009 and early 2010. These key issues include: 1) the use of effective dose and implications of incorporating the latest recommendations for tissue and radiation weighting factors; 2) the occupational dose limits; 3) the dose limits for special populations, such as the dose limit for the embryo/fetus of a declared pregnant woman; and 4) the use of constraints as a formal part of licensee radiation protection programs and the process of keeping exposures As Low As Reasonably Achievable.Learning Objectives:1. Understand the issues and background for possible changes to NRC's radiation protection regulations.2. Understand implications of possible changes, and provide user feedback to be incorporated into the ongoing technical basis development.
MO‐D‐BRA‐01: Nano ‐ Cancer and Radiation Therapy
Authors: Khan M , Lanza G , Miften M 
Published: August 2010

The field of nanotechnology in cancer includes the use of materials precisely constructed at the molecular level to develop devices and novel imaging and therapy techniques to improve the therapeutic ratio of cancer treatments. Recent advances in the application of nanotechnology to cancer hold a great promise to improve the detection, treatment, and prevention of cancer. In this scientific symposium, we will present a primer on the science of nanotechnology and discuss how it can be used to improve the imaging and treatment of cancer, including radiation therapy. We will describe the latest research and development in this exciting and rapidly advancing field. We will review newly developed cancer diagnostics and therapies, including the combination of imaging combined with drug delivery, based on nanotechnology and identify future directions.The specific objectives of the symposium are to:1. Provide a primer on nanotechnology in cancer and the science behind it.2. Describe the potential use of nanotechnology to improve the imaging of cancer and imaging combined with drug delivery.3. Describe the potential use of nanotechnology to improve the treatment of cancer, including radiation treatment.4. Describe the potential use of nanotechnology to deliver the treatment directly to the tumor while sparing healthy tissue, including radiation treatment.5. Describe promising newly developed cancer diagnostics and therapies based on nanotechnology, future directions, and the role medical physicists can play to advance the field.6. Describe the challenges of translating nanotechnology from the academic bench to the clinic.
MO‐D‐204B‐03: Correlation of PET Images of Metabolism, Proliferation and Hypoxia to Characterize Tumor Phenotype in Patients with HNSCC
Authors: Nyflot M , Harari P , Perlman S , Jeraj R 
Published: August 2010

Purpose: As positron emission tomography gains increasing prominence in tumor staging, radiotherapy target definition, and treatment assessment, better descriptions of tumor physiology are desired. In order to establish interrelation between tumor phenotypes, we have correlated PET images of metabolism, proliferation, and hypoxia in patients with head and neck squamous cell carcinoma (HNSCC). Method and Materials: PET/CT images of patients with HNSCC were acquired using [18F]FDG (a surrogate of metabolism), [18F]FLT (proliferation), and [61Cu]CuATSM (hypoxia). Patients were immobilized with thermoplastic head masks. Images were coregistered via bony anatomy and normalized to SUV. For each patient, ROIs were drawn on PET images over primary tumors (n=8) and nodal volumes (n=7). Correlation coefficients between FDG, FLT, and CuATSM distributions were calculated 1) at the voxel level, by comparing image values and 2) at the ROI level, by comparing mean SUV. Results: When comparing primary tumors at the voxel level, highest correlation coefficients were observed between FLT and FDG uptake. FDG:FLT on average had R=0.77 [range 0.52–0.89] compared to R=0.54 for FDG:CuATSM [range 0.09–0.79] and R=0.49 for FLT:CuATSM [range −0.02–0.76]. Nodal volumes showed similar trends. When comparing tumors at the ROI level, correlations were low (R<0.35) for all primary volumes and all nodal volumes except for FDG:CuATSM (R=0.72). Conclusion: FDG:FLT had the highest degree of correlation at the voxel level, while FLT:CuATSM and FDG:CuATSM exhibited high variability between patients. Voxel‐based regression of imaging surrogates may represent a superior technique to ROI‐based regression, which lacks spatial information, and is a valuable first step in the implementation of spatial correlation for tumor staging, radiotherapy target definition, or treatment assessment.Conflict of Interest: Research sponsored in part by Genentech.
MO‐D‐201C‐01: Advances in MR: State of the Art Today and Future Directions — MR Instrumentation
Authors: Pelc N.J. 
Published: August 2010

Even though Magnetic Resonance as a modality is now several decades old, instrumentation continues to advance at a vigorous pace. The purpose of this presentation is to review recent advances in the current state of the art and to discuss directions of continued progress. The main magnet continues to be the central platform component from the standpoint of cost and footprint. There has been steady increase in the number of clinical systems at higher field strength (e.g., 3T vs. 1.5T), and the expected increase in signal‐to‐noise ratio is now being realized. Another significant trend has been the increase in bore diameter and decrease in magnet length, both of which are appreciated by patients. A number of systems for human in‐vivo studies at even higher field strength (e.g., 7T) are now in use. These present significant technical challenges that are being addressed, especially in B0 and B1 homogeneity and in RF power deposition. The number of channels used for simultaneous signal reception also continues to increase, with related improvements in SNR and imaging speed through parallel imaging. A newer development is simultaneous RF transmission. This new field of “parallel transmission” promises to overcome problems with B1 homogeneity and perhaps power deposition. Hybrid systems that combine MR with other diagnostic or therapeutic modalities are also receiving attention. Among these hybrids are MR guided focused ultrasound, MR/PET, X‐ray/MR hybrids, and systems for MR guided radiation therapy systemsLearning Objectives:1. Recognize recent technology trends in Magnetic Resonance2. Understand the benefits and disadvantages of parallel excitation and reception3. Understand the challenges in combined modality systems4. Examine possible future directions for Magnetic ResonanceResearch sponsored by GE Healthcare.
MO‐D‐201B‐01: Carbon Nanotube X‐Ray: Promises and Challenges
Authors: Zhou Otto 
Published: August 2010

Purpose: To develop a carbon nanotube based field emission x‐ray technology for medical imaging and radiation therapy Method and Materials: Carbon nanotubes (CNTs) are used as the field emission “cold cathode”. The x‐ray tube current is generated by applying an external electrical field to extract the electrons from the CNTs. By varying the extraction electrical field, x‐ray radiation with programmable waveforms can be readily generated and gated with physiological signals. Spatially distributed x‐ray source arrays with one‐ and two‐ dimensionally distributed focal spots are constructed by using matrix addressable multi‐pixel CNT cathode. Switching, scanning, and regulating the x‐ray beams are achieved by specially designed gate control electronics. Results: Programmable and spatially distributed field emission x‐ray source arrays have been developed. After substantial R&D efforts these x‐ray sources are now capable of delivering the spatial resolution, the x‐ray flux, and the energy required for medical imaging applications. Utilizing the rapid programmable capability of the CNT field emission source, a prospective respiratory and cardiac gated micro‐CT scanner has been developed that is capable of high‐resolution in vivo imaging of free‐breathing small animals. A proof‐of‐concept stationary digital breast tomosynthesis scanner with a distributed multi‐beam x‐ray source array has been demonstrated which collects project images without mechanical motion and has the potential to substantially reduce the scanning time and therefore motion blurs. Utilizing the capability of distributing the x‐ray power over a large focusing track instead of small spot on the anode, a compact high dose and dose rate microbeam radiation therapy system is currently under development at UNC. Conclusion: The distributed field emission x‐ray source array technology offers unique capabilities that are attractive for tomography imaging and potentially for radiotherapy. The flexibility in source configuration opens up new possibilities in system design. As a brand new source technology, issues such as reliable and long term stability which are critical for commercial products need further investigation and improvement.Conflict of Interest: Zhou is a board director of XinRay Systems which develops and commercializes the CNT X‐Ray source technology.
MO‐E‐202‐01: A Primer on Proton Therapy
Authors: Palta J , Slopsema R , Engelsman M , Dong L 
Published: August 2010

The use of protons for radiation therapy offers theoretical advantages. Compared to external beam photon radiotherapy, proton therapy enables lowering of the integral dose to the patient due to the finite range of protons. However, proton therapy is less tolerant than photon therapy to uncertainties in both treatment planning and treatment delivery. Therefore, it is important to understand the potential sources of dosimetric uncertainties, the impact of these uncertainties in the accuracy and conformity of dose delivered to patients, and potential strategies that translate physical advantage of proton therapy into a maximized dosimetric benefit in the patient.One unique difference between proton therapy and photon therapy is that the dose distributions can be significantly affected by changes in anatomy and nearby tissue heterogeneities along proton beam directions. Photon‐based PTV is purely based on a geometric concept which disassociates spatial dose distribution from the movements of the patient and internal organs. The traditional PTV concept is inadequate for proton therapy, especially in the presence of setup errors, motion, and anatomical variations.This session will provide an overview of the state‐of‐the‐art in proton therapy. We will discuss in detail the management of planning and delivery uncertainties for both passively scattered proton therapy and the newest spot‐scanning proton therapy techniques.Learning Objectives:1. Understand the state‐of‐the‐art on proton therapy2. Understand the need for knowing potential sources of treatment planning and delivery uncertainties in proton therapy3. Learn strategies to mitigate both proton therapy planning and delivery uncertainties