bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐DD‐A4‐06: Instrumentation Noise Equivalent Exposure (INEE): An Investigation of Spatial Frequency Effects
Authors: Kuhls‐Gilcrist A , Jain A , Bednarek D , Rudin S 
Published: July 2008

Purpose: To expand on previous development of the instrumentation‐noise equivalent exposure (INEE) metric which directly quantifies the quantum‐limited performance range of a detector in terms of entrance exposure, by investigating spatial frequency dependence. Method and Materials: The INEE formalism assumes the total noise of an x‐ray detector is proportional to the incident number of quanta, with an additive term representing contributions resulting from instrumentation‐noise sources. The INEE then represents the threshold exposure below which the detector's performance is no longer driven by quantum statistics, becoming instrumentation‐noise‐limited and is measured using output signal variance plot versus exposure, fitted to . Similarly, to provide a spatial frequency dependent INEE, INEE(u,v), the two‐dimensional NPS (i.e. the variance of image intensity divided among the various frequency components of the image) was measured and plot as a function of exposure at each spatial‐frequency and fit with NPS(u,v)=k(u,v)(Exposure+INEE(u,v)). Output signal variance and NPS were measured using 90 flat‐field images on a digital x‐ray detector according to IEC guidelines and using the RQA 5 spectrum. Results: The measured INEE(u,v) was radially symmetric with the lowest INEE values at low spatial‐frequencies with an increasing INEE at higher spatial‐frequencies. The frequency behavior was determined to be largely dependent on the blur and scattering of the phosphor as described by the detector MTF. Frequency independent INEE was determined to be the weighted mean of INEE(u,v) with k(u,v), over all spatial frequencies. Conclusion: The INEE metric addresses the need for a direct, quantitative measure of the quantum‐noise‐limited exposure range of x‐ray detectors by providing the threshold exposure at which the detector instrumentation‐noise exceeds the quantum‐noise. Frequency dependence was investigated to provide a greater understanding of this promising new metric.(Support: NIH Grants R01‐NS43924, R01‐EB002873, Toshiba Medical Systems Corporation).
SU‐GG‐I‐16: A Segmentation Technique to Estimate Breast Density From Cone Beam Breast CT Images
Authors: Han T , Chen L , Lai C , Liu X , Shen Y , Wang T , Shaw C 
Published: July 2008

Purpose: To describe and demonstrate the use of an improved segmentation technique to estimate breast density from cone beam breast CT (BCT) images. Method and Materials: To compute the breast density, the dense tissue must be separated from the adipose tissue in the BCT images. To accomplish this task, the BCT images were first processed with a previously reported post‐reconstruction method to correct for the beam hardening and scatter induced cupping artifacts. With this method, the adipose signals were extracted from the coronal view CT image and used to form a 3‐D background map which was then subtracted from the original images for correction. The corrected data were edge enhanced and smoothed to reduce the noise levels in the images. The results were processed by threshold segmentation to separate the dense tissue from the adipose tissue and form a 3‐D dense tissue map which was then used to compute the dense tissue volume and the breast density. Results: For demonstration, the proposed technique was applied to cone beam CT images of mastectomy breast specimens to estimate the breast density. The cupping artifacts were successively corrected for and the dense tissue was successfully separated from the adipose tissue with the segmented dense tissue structures matching well with those visualized in the images. Conclusion: We have successfully implemented a method to use cone beam breast CT images to estimate the breast density. The technique was successfully demonstrated with cone beam CT images of mastectomy breast specimens. This technique lends itself to more accurate and consistent measurement of breast density which may be used an indicator for breast cancer risk.This work was supported in part by grants CA104759 and CA124585 from NIH‐NCI, a grant EB00117 from NIH‐NIBIB, and a subcontract from NIST‐ATP.
SU‐GG‐J‐145: Physics Support for Intraprostatic Treatment of Patients with Locally Recurrent Prostate Cancer with the PSA‐Activated Protoxin PRX302
Authors: Boyer A , Coffield S , Culp L , Frankel A , Merchant N , Abi‐Habib R 
Published: July 2008

Purpose: PRX302 is a protoxin in which the native furin‐cleaved pro‐domain has been modified to be proteolytically cleaved by PSA. PSA releases a C‐terminal inhibitory peptide to generate the active toxin, that inserts into the cell membrane to form 1.5 nm pores inducing ion leakage, loss of membrane integrity and cell death. We report on the physics support of a Phase I clinical trial of administration of PRX302 in patients with locally recurrent prostate cancer after radiation therapy. Method and Materials: 24 patients were enrolled. Dose‐escalation consisted of seven cohorts of 3 to 6 patients, each receiving a dose between 0.03 and 3 μg of PRX302/g of prostate. PRX302 was delivered as a multi‐deposit, transrectal ultrasound‐guided, transperineal injection using a modified brachytherapy technique. Images were acquired with a Hawk Type 2102 EXL (B&K Medical, Herlev, Denmark) ultrasonic unit using a rectal probe. The ultrasound display was calibrated against the needle template before each procedure. Commercial treatment planning software (Variseed. Varian Medical Systems) was adopted to select the location and concentration of the injections. Results: The maximal tolerated dose was not reached despite a 100‐fold dose increase. No drug‐related SAEs were observed. Preliminary data suggested biological activity of PRX302. PSA levels decreased in 63% of patients. The percentage of positive prostate biopsy cores post‐therapy decreased in 75% of patients with 3 patients having no positive cores at 30 days following PRX302 therapy. Conclusion: Active medical physics participation in these clinical trials contributed to the preliminary findings that transperineal administration of PRX302 is safe and well tolerated in patients with localized recurrent prostate cancer. MTD was not reached and PRX302 showed convincing signs of biological activity that will be further evaluated in future efficacy studies planned with medical physics input.Conflict of Interest: This Trial was sponsored by Protox Therapeutics, Inc.
SU‐GG‐J‐178: The Development of Eye Fixation Software for the Proton Therapy of Eye Tumors
Authors: Shin D , Yoon M , Lim Y , Kim D , Kwak J , Park S , Lee S , Park S , Cho K 
Published: July 2008

Purpose: Proton therapy is suggested as a next generation radiation therapy with their great dose localization performance compared with linear accelerator. Although proton therapy is recommended for eye melanoma treatment due to its excellence in dose localization, the patient positioning system (PPS) is essential since small error in PPS may cause significant damage to the patient. In this study, we developed an automatic real time eyeball tracking system for the treatment of eye melanoma. Method and Materials: A new automatic eye tracking system was developed using Labview 8.2 software with GUI based development tool (National Instrument), Vision development tool and image acquisition board(National Instrument). The real time image for eye movement was taken using CCD camera, which was transferred to the homemade image analysis program. Using computer outside the treatment room, a real time eye ball tracking based on image pattern matching method was realized by comparing a treatment template image used in the treatment planning with a real time image acquired from CCD camera. Results: Based on the real time image analysis system, we achieved the real time eye ball tracking system with a resolution less than 0.01mm for the eye ball movement which will be used for the treatment of ocular tumor in proton therapy. Conclusion: New automatic eye tracking system has been developed for ocular tumor treatment which is going to be used in the clinical trial with the gating system.Key words: Eye tracking system, Proton therapy, Ocular, Eye treatment.
SU‐GG‐T‐281: Quality Control in the Fabrication of Scintillating Fiber Probes for Radiotherapy Applications
Authors: Jones J , Briere TM , Archambault L , Beddar AS 
Published: July 2008

Purpose: Miniature plastic scintillation detectors (PSDs) and plastic scintillation detector arrays are highly useful in many radiotherapy applications. However, PSDs can show large detector variability between apparently identical detectors. Such variability may impact on the performance of a PSD array. The purpose of this work is to develop a quality control procedure to increase the uniformity of PSDs. Method and Materials: A uniform procedure for fabricating PSDs was established. A quality control bench was then designed, which comprised a precise positioning mechanism, an ultraviolet LED for stimulating the scintillation light in plastic scintillators and a spectrometer to characterize the relative emission spectra of the PSDs as well as their total light output. The reproducibility of the bench itself was evaluated by measurements of a single detector through numerous mounting, un‐mounting cycles. A batch of 15 PSDs was then built and tested for quality. Results: The quality control bench could be used with an average reproducibility of 0.7%. Stimulation of the plastic scintillators by ultraviolet light produced the same emission spectrum as one obtained from ionizing radiation. Quality control measurements for the 15 PSDs showed no major discrepancies in the relative emission spectrum. However, large variations in total light output were observed. The standard deviation of the total light output was 16%, with a maximum variation of 28%. Of all detectors, 13% had a total light output of 0.85 or less relative to the mean. Conclusion: The precision of a plastic scintillation detector will suffer if its total light output is too low. In this work, we have developed a tight quality control procedure for PSDs that could improve the performances of PSDs and PSD arrays. This procedure can be used to prevent detectors with poor light output from being used.Supported by the NCI (1R01CA120198‐01A2).
MO‐A‐AUD C‐01: Practical Considerations for Respiratory Colarated CT Imaging and Target Volume Delineation
Authors: Mutic S 
Published: July 2008

Accurate and conformal treatment of tumors in abdomen and thorax is challenging due to respiratory related motion. Respiratory corralled CT imaging combined with gated treatment delivery can improve both accuracy and conformality of delivered dose distributions. Implementation of respiratory correlated imaging and treatment delivery can be performed in multiple ways and understanding of different techniques and technical challenges is critical for efficient and safe clinical implementation. Formal recommendations for commissioning and clinical use of this technology is scarce. Inadequate evaluation and understanding of these systems can lead to significant treatment errors. This presentation deals with practical issues of respiratory correlated CT imaging and commissioning. Examples of some commonly seen image artifacts are also discussed. Furthermore, contouring based on respiratory correlated images is discussed, again with examples of some of potential pitfalls and artifacts.Education Objectives:1. Commissioning process for respiratory correlated CT imaging and delivery techniques.2. Use of respiratory correlated images for target delineation.3. Common image artifacts and contouring errors seen with respiratory correlated imaging.
MO‐SAMS‐332‐01: The Principles of Quantitative MRI
Authors: Clarke G 
Published: July 2008

The applications of magnetic resonance imaging (MRI) in biomedicine are undergoing rapid evolution. Typically used to produce images that are viewed and subjectively rated by a radiologist, MRI is now being utilized as a scientific apparatus capable of making noninvasive measurements in living tissues. With care, a significant number of physical and biological measurements can be performed and related to individual pixels and groups of pixels in the MR image. This presentation will address the challenges in obtaining quantitative data from MRI.The presentation will review the principles of good practice in quantification, including quality assurance, MR data collection, and analysis. Limits on precision and accuracy are discussed and solutions proposed. Three major topics are considered. First, the signal collection process in MRI will be reviewed concentrating on geometrical relationships derived from MR images and signal‐to‐noise considerations. Then, physical sources of quantitation errors in MRI will be considered; especially resonant frequency offsets, radio frequency (RF) attenuation, dielectric phenomena and eddy current effects. Third, common quantitative measurements using MRI will be explored. The principles underlying the measurement of each quantity are given along with their biological and medical significance and practical approaches for achieving their accurate measurement. Shortcomings of the measurement processes and a summary of potential clinical applications are also discussed. Pathological and developmental observations will be also compared with MRI‐derived quantities where appropriate.This presentation is intended as an introduction to the field of measurement in MRI for anyone who desires to use the scope of modern measurement techniques to quantitatively determine the consequences of disease, its development or its reaction to therapy from MR images. It will be of interest to medical physicists who are considering undertaking quantitative work with MRI, as well as those already in the field.Educational Objectives:1. Appreciate the clinically important quantities that can be measured with MRI.2. Be familiar with the methods and techniques used for quantitative MRI.3. Have a basic understanding of the limits on precision and sources of error in quantitative MRI.
MO‐B‐352‐01: The Clinical Perspective — Multimodality and Multidimensional Imaging
Authors: Vannier M 
Published: July 2008

Modalities like optical, CT, MR, PET/SPECT and US are used separately, but can be combined. Multimodality imaging is necessary when the results of two (or more) modalities differ, and each does something useful but not everything that's required. We will consider several practical examples: residual or recurrent tumor after treatment, eloquent cortex in the brain when a lesion is nearby, drug effect in situ — especially for cytostatic agents, control of thermal ablation, vulnerable plaque, evaluation of gene therapy, and assessment of revascularization benefits depending on tissue viability. All of these scenarios can be detected in one modality, where another provides a morphologic reference useful for guiding therapy.Not only are imaging modalities synergistic, but their performance can be altered and utility extended using exogenous agents, such as contrast media, radiopharmaceuticals, and other targeted compounds with desirable in vivo biological and physical characteristics. Optimizing the combination of modalities, agents, data acquisition, image reconstruction, visualization and analysis can be challenging, but may provide unique capabilities that no single technique could offer.We will evaluate the state‐of‐the‐art for combining modalities in animals and show how this could translate to clinical practice, recognizing the impediments of cost, complexity, reliability, crosstalk, and safety/regulatory restrictions. The need and potential for multimodality techniques and systems already far exceeds what's currently available, so we can identify some unsolved problems where the benefits are not yet available.Educational Objectives1. To understand the synergy between modalities (optical, CT, MR, PET/SPECT, US), contrast agents or tracer compounds, and post‐processing image analysis that provides multimodality and multidimensional capability.2. To provide examples of how multimodality/multidimensional imaging can solve clinical problems in diseases of the brain, cardiovascular system, cancer, and for regenerative medicine.3. To identify several unsolved problems where multimodality/multidimensional imaging may provide clinically useful solutions.
MO‐E‐342‐01: Nuclear Medicine Instrumentation
Authors: Turkington T 
Published: July 2008

Nuclear Medicine instrumentation continues to progress, both hardware and software. Advances in PET/CT include increased PET sensitivity, respiratory gating, time of flight measurement, and improved image reconstruction algorithms that encorporate more physical effects into the acquisition model. Gamma cameras are incorporating new detector materials, and SPECT is being done with new acquisition geometries and reconstructed with new algorithms.We will discuss new developments in nuclear medicine instrumentation, including ones that are currently available commercially and ones that are on the horizon.Educational Objectives:1. Understand three new developments in PET that have the potential to improve image quality.2. Understand how new detector materials allow new acquisition geometries for SPECT.3. Understand how physic effects in the acquisition process can be modeled in the image reconstruction process.Research sponsored by GE Healthcare.
TU‐SAMS‐AUD B‐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: July 2008

Three‐dimensional conformal radiotherapy (3D‐CRT), intensity‐modulated radiotherapy (IMRT), and body stereotactic radiotherapy (BSRT) 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.Educational Objectives:1. To review kV‐CBCT and MV‐CBCT imaging systems for daily localization including:a. Commissioning, image quality, dose, registration process, and acquisition modes.b. Clinical integration.c. QA, stability over time, and downtime.d. Standard clinical applications.e. Novel clinical applications.f. Technology evolution and future directions.
TU‐SAMS‐332‐01: Film‐Screen Mammography QA: What You Need to Know
Authors: Schueler B 
Published: July 2008

The medical physicist provides a valuable service to mammography facilities by helping to ensure the production of high quality images at a low radiation dose. This presentation will describe the role of the medical physicist in mammography QA and equipment performance evaluation of film‐screen systems. Individual tests for both initial and annual equipment evaluations will be described. Special attention will be paid to potential pitfalls, common problems and ways to increase efficiency of the testing process.Educational Objectives1. Review medical physicist responsibilities in film‐screen mammography QA.2. Learn about the specific requirements involved in testing for new equipment installations.3. Review quality control procedures for annual equipment performance evaluations.4. Learn about ways to streamline equipment performance evaluations.
TU‐B‐342‐01: SPECT/CT and PET/CT Dosimetry
Authors: Fahey F 
Published: July 2008

This presentation will discuss the dosimetric factors associated with PET/CT and SPECT/CT including those associated with the administration of radiopharmaceuticals for both PET and SPECT and the specific factors associated application of CT in these hybrid modalities. The dosimetry of the application of these modalities to pediatrics will also be discussed. For SPECT, the dosimetry of the administration of radiopharmaceuticals typically used in SPECT as well as potential methods for maintaining these doses at reasonably low levels. In particular, myocardial perfusion imaging will be discussed. Also the use of new reconstruction techniques and how they may be used to lower the administered activity for some SPECT applications will be discussed. For PET, the dosimetry associated with the use of fluoro‐deoxy‐glucose (FDG) will be discussed including different technical approaches that may lead to lower administered activity. Lastly, the application of CT to both SPECT and PET will be discussed including the requirements for CT‐based attenuation correlation, anatomical correlation and diagnostic CT. Potential methods to reduce CT dose in these protocols will be discussed.Educational Objectives:1. Discuss 2 potential ways to reduce the administered activity in SPECT.2. Describe 2 ways that the acquisition of PET can be modified to make it more efficient.3. List 3 approaches that can be used to reduce the dose of the CT used in conjunction with PET and SPECT.
TU‐C‐AUD B‐03: A Comparison of Heterogeneity Correction Algorithms
Authors: Alvarez P , Molineu A , Hernandez N , Hall F , Followill D , Ibbott G 
Published: July 2008

Purpose: To compare the measured dose distribution to the planned distribution over a PTV centrally located within the lung when heterogeneity corrections are taken into account. Method and Materials: The Radiological Physics Center has constructed an anthropomorphic thorax phantom that includes a target (∼ 1 g/cm3) centrally located in the left lung (∼ 0.33 g/cm3). The phantom was irradiated by 33 institutions with results that meet criteria established for the RTOG 0236 protocol. TLDs and radiochromic films were used as dosimeters within the target region. Institutions were asked to design plans using 3D‐CRT and IMRT techniques. The TLD dose was compared to the dose calculated by the TPS at the center of the target. Film response was normalized to TLD doses and a 2D‐gamma analysis comparison to the planned distribution was performed. Institutions whose irradiation of the phantom did not meet the RTOG 0236 criteria were not included. Results: A 2D‐Gamma analysis was done in the axial, sagittal and coronal planes through the PTV. 5% / 5mm criteria were applied. Due to limitations of the analysis software only the comparison over the axial plane is reported. 21 of the cases were planned with a superposition/convolution or AAA algorithm. For these cases, 92% ± 12% of the pixels in the analyzed region met the criteria. 12 of the cases were planned with a pencil beam or Clarkson algorithm. 74% ± 25% of the pixels meet the criteria for these cases. Conclusion: The superposition convolution heterogeneity correction algorithm showed better agreement with the measured dose distribution across the PTV than the pencil beam and Clarkson algorithms.Work supported by PHS grant CA10953 and CA081647 from the NCI, DHHS.