bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐FF‐I‐147: Monte Carlo Based Evaluation of 3D PET Quantification Inaccuracy for the Lung
Authors: Kang H , Schmidtlein CR , Mitev K , Gerganov G , Madzhunkov Y , Humm JL , Amols HI , Kirov AS 
Published: April 2010

Purpose: Our goal is to investigate the effect on PET accuracy of the various physical and instrumental phenomena using realistic Monte Carlo (MC) models of patient activity distributions and PET scanners. Methods and materials: Data from a lung PET/CT scan is used to create numerical voxelized phantom for realistic MC simulations using the GATE MC code. We compared the activity reconstructed from the simulations to the input (“true”) values. We investigated the effects of random coincidences, photon scatter and positional shift between transmission and emission scans on the degradation of 3D PET quantification accuracy. Results: When exact attenuation, scatter and random corrections are applied, the activity from the simulated scans deviated from the input by more than 50% for 25% of the voxels. Inaccuracy of the random and scatter corrections of 20% will add additional quantification errors of about 20% and 40% respectively. The attenuation correction (AC) adds random and scatter events to the high tissue density regions. AC based on misaligned transmission data causes pronounced changes in the activity distribution in regions that have a high density gradient such as at junctions between soft tissue, bone and lung. AC misalignment causes errors of the activity levels, which may exceed a factor of five around the ribs for 1.5 cm shift between the PET data and the AC image. Conclusions: MC methods are a useful tool in investigating PET scanner response to realistic distributions of the activity and the attenuation properties and in establishing the uncertainty in PET quantification in patient studies. The potential quantification errors due to possible misregistration and inaccurate scatter and random corrections have been determined as indicated above for the lung.Supported in part by NCI grant CA‐059017 and performed in part on the Physon cluster, funded by Bulgarian NSF contract DO‐1‐872.
SU‐FF‐I‐165: Ultrasound Transducer Performance Evaluation Summary for a Large Multi‐Specialty Clinic
Authors: Kruger R 
Published: April 2010

Purpose: The objective of this study was to evaluate and identify the type of element failures found in ultrasound transducers used in our clinical practice.Method and Materials: Assessing transducer functional performance was accomplished using the Sonora FirstCall Test System, Sonora Medical Systems Inc. (Longmont, CO, USA). This system is an ultrasound transducer tester, which can test all essential transducer parameters according to FDA regulation 21CFR 820. The system was used to evaluate 199 transducers at 7 clinical sites from September 2007 to December 2008. All transducers were of the same manufacturer and may have been tested up to three times. The test system is connected to the transducer but not the ultrasound scanner. Each transducer element is tested and evaluated. The test is performed in water, where the elements are activated one by one using a metal target plate to reflect the ultrasound pulse emitted by each activated element. The returning pulse is analyzed by means of the peak‐to‐peak amplitude, center frequency, pulse width, bandwidth, and the pulse waveform. Additionally, the accumulated capacitance of every element is evaluated and element electrical integrity is tested identifying electrical failures. Results: This investigation found that 35 transducers (17.6%) failed our acceptance criteria. The 199 transducers evaluated during this study consisted of 5,168 total elements. An evaluation of the 35 transducers that failed our acceptance criteria resulted in a total of 291 elements that had one of the following defects: dead elements, lens delamination, wire cuts, capacitance short. Conclusion: Ultrasound Quality Assurance measurements using a commercial phantom are subjective and can require a considerable investment. Our survey indicates an urgent need for increased quantitative testing of the transducers in clinical departments, such testing should augment the current QA program to insure the highest quality performance of clinical ultrasound systems.
SU‐FF‐I‐171: New High‐Resolution Detector Changer for a Clinical Fluoroscopic C‐Arm Unit
Authors: Wang Weiyuan , Keleshis C , Kuhls‐Gilcrist A , Ionita C , Jain A , Bednarek D , Rudin S 
Published: April 2010

Purpose: To investigate a means to alternate image acquisition between a high‐resolution region‐of‐interest (ROI) detector and a standard flat‐panel detector (FPD) when used for neurovascular image‐guided interventions with a clinical fluoroscopic C‐arm so that the larger area detector could be used during initial parts of a procedure and the high‐resolution detector used during critical parts of the intervention when better images are needed. Method and Materials: A new detector changer was designed, fabricated, and mounted on a clinical fluoroscopic unit to allow a ROI detector such as the Micro‐Angiographic Fluoroscope (MAF) or Solid‐State X‐ray Image Intensifier (SSXII) to be introduced in front of the standard FPD to enable high‐resolution fluoroscopy, DSA, and conebeam computed tomography. The x‐ray collimation automatically adjusts the field‐of‐view (FOV) when the changer inserts or retracts the ROI detector so that the correct FOV, smaller for the ROI detector or larger for the FPD, respectively, is implemented. A touch sensor at the front of the ROI detector holder causes the entire imaging unit (FPD and ROI detector) to retract upon physical contact in order to avoid collision with a patient or other objects on or near the table. Results: The new detector changer has been installed onto a Toshiba Infinix clinical fluoroscopic C‐arm unit. The changer provides stable support for the ROI detector, allowing operator selection of high‐resolution ROI or standard FPD. The collision avoidance and automatic collimation features have worked reliably during laboratory evaluation and should provide a patient‐safe imaging capability. Conclusion: The new detector changer mounted on a commercial clinical fluoroscopic C‐arm unit provides a safe and rapid means to exchange imaging detectors to accommodate the resolution requirements of angiographic and interventional vascular imaging during the course of a procedure.(Partial support: NIH Grants R01‐EB008425, R01‐EB002873)
SU‐FF‐J‐24: Functional Planning for Tomotherapy‐Based Stereotactic Body Radiotherapy (SBRT) for Peripheral Lung Tumors
Authors: Cai J , McLawhorn R , Read P , Larner J , Sheng K , Altes T , de Lange E , Benedict S 
Published: April 2010

Purpose: To investigate the impact of incorporating hyperpolarized heliume‐3 (HP He‐3) MRI ventilation images to Tomotherapy‐based stereotactic body radiation therapy (SBRT) planning for peripheral lung tumors. Method and Materials: CT and HP He‐3 MRI ventilation images of 6 subjects were co‐registered for segmentation. Highly functional lungs (HFL) were defined as the 70‐percentile hyperventilation lungs and less functional lungs (LFL) were subsequently calculated. A cylinder‐shaped artificial object was created in peripheral lungs to mimic planning‐target‐volume (PTV). Two Tomotherapy‐based IMRT plans, a anatomical plan (Plan 1) and a functional plan (Plan 2), were designed with SBRT‐type prescription (60Gy in 5 fractions) and normal tissue constrains. The following dosimetric parameters were compared between two plans: total lung V20 (TLV20), highly functional lungs V20 (HFLV20), less functional lungs V20 (LFLV20), mean total lung dose (MTLD), mean highly functional lung dose (MHFLD), mean less functional lung dose (MLFLD), max dose to organs at risk (OARs) and conformality index (CI). Results: Compared to Plane 1, Plan 2 significantly reduced HFLV20 (median reduction 2.1%, range 0.7–2.9%, p‐value=0.031), TLV20 (median reduction 1.6%, range 0.5–2.1%, p‐value=0.031), MHFLD (median reduction 0.8Gy, range 0.4–1.0Gy, p‐value=0.031), and MTLD (median reduction 0.7Gy, range 0.1–1.0Gy, p‐value=0.031). There was no significant difference in LFLV20 and MLFLD (p‐value is 0.438 and 0.156 respectively). Dose constrains for OARs were satisfied in all plans and max doses to OARs were not significantly changed in Plan 2 (p‐values range: 0.063–0.563). CI was generally reduced in Plan 2 (median reduction 0.02) but the difference is insignificant (p‐value=0.125). Conclusions: The incorporation of HP He‐3 MRI ventilation information to the Tomotherapy‐based SBRT planning for peripheral lung cancer improved the sparring of radiation dose to highly functional lungs and can potentially preserve more highly functional lungs.Conflict of Interest: Dr. Paul W. Read serves as a consultant for Tomotherapy Inc.
SU‐FF‐J‐27: Calibration of the Dual‐Transducer Focused Acoustic Radiation Field for a Multimodal Sono‐Contrast NIR Spectroscopy System
Authors: Yan K , Huang K , Podder T , Yu Y 
Published: April 2010

Purpose: To calibrate the dual‐transducer focused acoustic radiation field, register the focus center in the imaging ultrasound system, and establish a monthly calibration protocol for a noninvasive multi‐modal breast cancer scanning system. Method and Materials: The scanhead incorporated two 1MHz focused transducers aligned orthogonally to deliver acoustic radiation force (ARF) in a 2.4cm region. A commercial ultrasound probe, located in the same vertical plane as the focused transducers, was used in the system for image co‐registration. Dielectric fluid was filled into the scanhead as the ultrasound transmission media. The scanhead was merged into a water tank filled with degassed distilled water. A function generator connected with an amplifier was used to drive the focused transducers. The imaging ultrasound probe was connected to a commercial ultrasound system. The focused transducers were excited by 1MHz continuous sine wave with amplitude of 200mv from a function generator, amplified by the amplifier. A hydrophone was aligned vertically below the bottom plate and moved by a 3D motion platform (resolution 0.05mm) in the 3D Cartesian space at a step of 0.1mm. An oscilloscope was connected with the hydrophone for data display and acquisition of the voltage signals for calculating the acoustic intensity. Results: The focal spot that has the maximum peak‐positive voltage signal on the oscilloscope was found at 2.34 cm below the bottom plate, which is the designed intersection of the axes of the two focused transducers. The Spatial Peak Temporal Average Intensity was determined to be 0.4 W⋅cm−2, below the FDA therapeutic ultrasound limits (0.72 W⋅cm−2). The focal spot was then registered in the imaging ultrasound images. Conclusions: This study established the baseline of the dual‐transducer focus acoustic radiation field. A monthly calibration protocol has been developed following the same procedure for the focused acoustic radiation field.Acknowledgement: supported by NCI Grant CA107860.
SU‐FF‐J‐35: Severe Inter‐Fractional Anatomic Changes and Their Dosimetric Impact in Abdominal Irradiation, An Indication for Adaptive Re‐Planning
Authors: Qi X , Wang K , Siker M , Firat S , Erickson B , Li X 
Published: April 2010

Purpose: To study the dosimetric impact of inter‐fractional anatomic changes in the abdominal region during the course of radiation therapy and to determine the frequency of adaptive re‐planning. Methods and material: Daily CT images acquired for selected abdominal cancer patients treated on a helical Tomotherapy unit were analyzed. The targets and organs at risk (OAR), such as kidneys, liver, cord and stomach, were delineated based on daily CT registered with the planning CT. The 3D dose distribution and dose volume histograms (DVHs) delivered to the patient on the day were reconstructed based on the CT of the day and the shifts performed (verification dose) using the Planned Adaptive software in the Tomotherapy planning system. The daily patient anatomy including body weight and locations, volumes and shapes of targets and OARs, as well as dose volume parameters including DVHs, maximum, minimum and mean doses and equivalent uniform dose (EUD) were compared to those from the planning CT. Results: Significant interfractional anatomic changes were observed for a patient with severe weight loss. In this patient with a suprarenal tumor, significant weight loss was observed during the second week (day 8) of radiotherapy, which led to 6.2%, 10.3% and 7% increases in maximum doses for PTV, the cord and unspecified tissue, respectively, from their values in the original plan. Compared to the original plan, the EUD changed by 24.6%, 11.3% and 14.6% respectively, for the right kidney, liver and stomach. In a cholangiocarcinoma case, dramatically organ volumetric and/or geometric changes for the liver and stomach were observed, resulting in changes in EUD of 16%, 22% and 46% for the liver, stomach and left‐kidney, respectively.Conclusion: Dramatic inter‐fractional anatomic changes in abdominal region, which can result in significant dosimetric impact and therefore, should be accounted for by an adaptive strategy, such as re‐planning.
SU‐FF‐J‐45: Performance of a PET‐Guided Breast Biopsy System
Authors: Matthews CG , Kalinyak JE , Payne S , Kassab R , Luo W 
Published: April 2010

Purpose: Positron emission mammography (PEM) imaging has identified lesions with no anatomic correlate, thereby creating a need to sample using only PET guidance. Bench tests were designed to validate the first PET‐guided breast biopsy system for clinical use. Method and Materials: A commercially available Naviscan PET scanner with its Stereo Navigator breast biopsy accessory is used with third party, vacuum‐assisted, core needle biopsy (CNB) devices. A series of bench tests with phantoms determined the performance of the system for breast biopsy. The targeting accuracy test series compared the physical versus image coordinates in 3D of radioactive targets. The guidance accuracy test series checked the placement in guiding biopsy needles to the correct position such that it would intersect with a Na‐22 point source, i.e., replicating the guidance of a biopsy needle to a suspected lesion in a human breast. The glyph placement accuracy series verified the software glyph overlays correlated to the physical location of the guidance hardware and biopsy needle. The biopsy sampling test series evaluated the ability of the system to accurately target an FDG lesion, to confirm localization of the lesion using a Ge‐68 line source, and to verify accurate sampling with CNB tools Results: Targeting accuracy was found to be 0.5 ± 0.3 mm in‐plane and 1.0 ± 0.9 cross‐plane. The needle guidance accuracy was 0.9 ± 0.6 mm parallel to the needle and 2.3 ± 1.3 perpendicular to the needle. The computer‐generated glyphs were correctly placed with respect to the physical target location 100% of the time. The biopsy sampling was 96% successful. Conclusion: Bench testing of the first PET‐guided breast biopsy system demonstrated a high degree of guidance accuracy for use in PEM‐identified breast lesion sampling. The system was cleared for clinical use.Conflict of Interest: Research sponsored by Naviscan, Inc.
SU‐FF‐J‐46: Treatment of Bone Metastases Using MR Guided Focused Ultrasound
Authors: Chen L , Ma C , Richardson T , Freedman G , Konski A 
Published: April 2010

Purpose: To evaluate the safety and efficacy of MR guided focused ultrasound (MRgFUS) treatment for bone metastases. Method and Materials: A 50‐year‐old patient with painful scapula bone metastases refractory to pain medication was recruited in this study. The treatment was performed under local IRB approval using an MRgFUS system consisting of an Insightec ExAblate 2000 with a GE 1.5T MR scanner. The focal region is approximately 2mm in diameter and 10mm in length. Beside the regular monthly and annual quality assurance (QA) measurements, pre‐treatment machine calibration included the functionality of the treatment software and the mechanical motion control. The focal spot was verified using MR thermometry. The safety system and panic buttons were checked. The patient is positioned on a gel pad on the treatment table in line with the transducer. The gel pad was immersed in degassed water that acts as an interface between the treatment table and the gel pad for acoustic coupling. Caution was taken with all gas bubbles removed between the interfaces. Treatment was performed under conscious sedation. Six sonications were delivered with frequency 1 MHz, acoustic power 32 ±4 W, energy 628±78 J and 20s durations. Phase MR Images were used to monitor the temperature change in real‐time. Based on the treatment feed back, acoustic power was adjusted to reach designed temperatures (⩾60 °C) for individual sonications. Results: The patient tolerated the MRgFUS treatment well. There were no treatment‐related adverse events including skin toxicity. The patient reported rapid pain decrease from 8 out of 10 (0 – 10 scale) pretreatment to 2 within 24 hrs, and has continued to report between 2 – 2.5 up to 2 months following treatment.Conclusions: MRgFUS is a safe, effective and noninvasive treatment modality for bone palliation and pain relief. A comprehensive QA program has been developed for the MRgFUS system.
SU‐FF‐J‐49: Geometric Validation Of MV‐Topograms And Digitally Reconstructed KV‐Topograms
Authors: Goddu S , Palaniswaamy G , Moore K , White B , Yang D , Rangaraj D , Mutic S , Low D 
Published: April 2010

Purpose: While Tomotherapy offers volumetric Imaging for image‐guided radiation‐therapy, it suffers from the drawbacks of slow image‐reconstruction, and lack of planar imaging capability. Megavoltage (MV) topograms and kilo‐voltage digitally reconstructed topograms (kV‐DRTs), have the potential for reducing daily‐localization times and patient‐dose. Both kV‐DRTs and MV‐topograms were generated using our in‐house Topographic Registration (TopoReg) Software. Primary goals of these tests were to validate the geometric integrity of the topograms in all 3‐ dimensions. Methods: TopoReg software uses high‐resolution CT‐datasets for reconstructing the kV‐DRTs while the MV‐topograms are created from the Tomotherapy exit detector data. TopoReg software includes several tools for image enhancement and registration. Geometric verification of the reconstructed topograms was done in three steps; planar, volumetric, and anthropomorphic. The first phantom includes four 17×17×0.5 cm3 water‐equivalent plastic (WEP) plates fixed on top of a 40×40×1 cm3 WEP for planar verification. There were two sets of holes on each WEP plate, separated by 12.5 cm. The second phantom was a Styrofoam cube (30×30×30 cm3) with embedded WEP plates; two plates on the diagonal axis and one plate on each side. Head and neck, thorax, and pelvis phantoms were also imaged and compared. The phantoms were imaged using Brilliance Large bore CT scanner and kV‐DRTs were generated. MV‐topograms were generated from the exit detector data. Results: Geometric verification was conducted by comparing fiducial positions on the topograms. MV‐topograms are overlaid on kV‐DRTs for registration. Both translations and rotations were allowed during image registration. Geometric accuracy was within ±1 mm in all 3‐dimensions and the image quality of the topograms was adequate for bony anatomy‐based registrations. Conclusion: TopoReg software is valid and the geometric accuracy of the MV‐topograms and kV‐DRTs was acceptable for clinical implementation.This work supported in part by a grant from Tomotherapy.
SU‐FF‐J‐67: Marker‐Less Verification of Respiratory‐Gated Radiotherapy for Lung Cancer
Authors: Berbeco R , Aristophanous M , Rottmann J , Park S 
Published: April 2010

Purpose: To maximize the potential benefit of respiratory gating for lung tumors, a method of image‐guided verification is necessary. We propose using the MV EPID in cine mode during respiratory‐gated radiotherapy to verify the location of the tumor without the aid of implanted fiducials. Method and Materials: The verification procedure to be studied is as follows: prior to each fraction of gated radiation therapy, a gated radiograph is acquired for each of the therapy beam angles. This reference image is then compared to cine EPID images acquired during respiratory‐gated radiotherapy. The target can be visualized in the images and the deviation from the reference position calculated. Phantom studies were performed using a dynamic phantom and internal respiratory traces derived from patients undergoing lung SBRT treatments. Setup images were taken when the external surrogate signal was in the reference (exhale) position and gated radiotherapy was simulated using clinically realistic fields. The reference and treatment images were loaded into offline research software and the location of the target relative to the reference was calculated using a template matching algorithm. Clinical patient data has also been used to demonstrate the feasibility of the technique for an oblique treatment beam. Results: Preliminary phantom and clinical studies demonstrate that the target can be tracked through a series of MV cine EPID images. From both studies, accuracy was assessed to be better than 1 mm. Conclusion: A procedure for confirming the target location during lung cancer respiratory‐gated radiotherapy without the aid of internal fiducials has been defined. Although the proposed procedure is demonstrated retrospectively, in principle, in could be performed in real‐time.Conflict of interest: Research funded, in part, by Varian Medical Systems, Inc.
SU‐FF‐T‐04: Permanent Brachytherapy Seed Localization Via Iterative Forward Projection Matching (IFPM) Algorithm Using Intraoperative Cone‐Beam CT Sinogram Projections
Authors: Pokhrel D , Murphy M , Todor D , Lazos D , Weiss E , Motai Y , Williamson J 
Published: April 2010

Purpose: To experimentally validate a new algorithm for reconstructing the 3D positions of implanted brachytherapy seeds from intraoperatively acquired 2D cone‐beam CT sinogram projections. Methods and materials: The iterative forward projection matching (IFPM) algorithm consists of finding the 3D‐seed geometry that minimizes the sum‐of‐squared‐intensity differences between computed projections of the candidate seed array positions and experimentally acquired auto‐segmented projections of the implanted seeds. Starting with clinically reasonable initial‐estimate of the seed configuration, e.g., the ultrasound pre‐plan, IFPM iteratively refines the 3D‐seed coordinates and the imaging view‐points until the computed and measured projections match. Four post‐implant patients were scanned using an Acuity digital‐simulator with a full 660 projections conebeam‐CT(CBCT) for post‐implant dosimetry. 3–10 x‐ray images were selected from the CBCT sinogram and were preprocessed to create the binary seed‐only images. 2D Gaussian functions centered at each binary image centroid were used to create gray scale images. The Gaussian width was reduced when IFPM converged. To quantify IFPM accuracy, the reconstructed seed positions were forward projected and overlaid with the measured seed images and found the nearest‐neighbor‐distance between computed and measured seed positions for each image‐pair. Results: For all example cases, the mean registration error was found to be about 1.2mm; the IFPM converged in 16–21 iterations and in 4–7 iterations following reduction of Gaussian blurring function width with computation time of about 1.9–2.3 minutes/iteration on a 2 GHz processor. Discussion: The IFPM algorithm avoids the need for matching corresponding seeds images on each projection as required by standard back‐projection methods. Also it has a potential to accommodate incomplete data by iteratively recreating the overlap seeds on the matching computed projections. Our preliminary results of the patient's studies demonstrated that ∼1mm accuracy in reconstructing the 3D‐positions of brachytherapy seeds from the measured 2D projections.Supported by Varian‐Medical‐Systems