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https://www.readbyqxmd.com/read/28088808/shunt-surgery-in-idiopathic-intracranial-hypertension-aided-by-electromagnetic-navigation
#1
Elvis J Hermann, Manolis Polemikos, Hans E Heissler, Joachim K Krauss
BACKGROUND: Idiopathic intracranial hypertension (IIH) is characterized by increased cerebrospinal fluid (CSF) pressure and normal or slit ventricles. Lumboperitoneal shunting had been favored by many investigators for CSF diversion in IIH for decades; however, it has been associated with various side effects. Because of the small ventricular size adequate positioning of a ventricular catheter is challenging. OBJECTIVES: Here, we investigated the usefulness of electromagnetic (EM)-guided ventricular catheter placement for ventriculoperitoneal shunting in IIH...
January 14, 2017: Stereotactic and Functional Neurosurgery
https://www.readbyqxmd.com/read/28079677/cadaveric-testing-of-robot-assisted-access-to-the-internal-auditory-canal-for-vestibular-schwannoma-removal
#2
Neal P Dillon, Ramya Balachandran, Michael A Siebold, Robert J Webster, George B Wanna, Robert F Labadie
HYPOTHESIS: An image-guided robotic system can safely perform the bulk removal of bone during the translabyrinthine approach to vestibular schwannoma (VS). BACKGROUND: The translabyrinthine approach to VS removal involves extensive manual milling in the temporal bone to gain access to the internal auditory canal (IAC) for tumor resection. This bone removal is time consuming and challenging due to the presence of vital anatomy (e.g., facial nerve) embedded within the temporal bone...
January 10, 2017: Otology & Neurotology
https://www.readbyqxmd.com/read/28074785/deformable-registration-of-ct-and-cone-beam-ct-with-local-intensity-matching
#3
Seyoun Park, William Plishker, Harry Quon, John Wong, Raj Shekhar, Junghoon Lee
Cone-beam CT (CBCT) is a widely used intra-operative imaging modality in image-guided radiotherapy and surgery. A short scan followed by a filtered-backprojection is typically used for CBCT reconstruction. While data on the mid-plane (plane of source-detector rotation) is complete, off-mid-planes undergo different information deficiency and the computed reconstructions are approximate. This causes different reconstruction artifacts at off-mid-planes depending on slice locations, and therefore impedes accurate registration between CT and CBCT...
February 7, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28066887/the-effect-of-beam-purity-and-scanner-complexity-on-proton-ct-accuracy
#4
P Piersimoni, J Ramos-Méndez, T Geoghegan, V A Bashkirov, R W Schulte, B A Faddegon
PURPOSE: To determine the dependence of the accuracy in reconstruction of relative stopping power (RSP) with proton computerized tomography (pCT) scans on the purity of the proton beam and the technological complexity of the pCT scanner using standard phantoms and a digital representation of a pediatric patient. METHODS: The Monte Carlo method was applied to simulate the pCT scanner, using both a pure proton beam (uniform 200 MeV mono-energetic, parallel beam) and the Northwestern Medicine Chicago Proton Center (NMCPC) clinical beam in uniform scanning mode...
January 2017: Medical Physics
https://www.readbyqxmd.com/read/28048917/su-f-j-201-validation-study-of-proton-radiography-against-ct-data-for-quantitative-imaging-of-anatomical-changes-in-head-and-neck-patients
#5
A Hammi, D Weber, A Lomax
PURPOSE: In clinical pencil-beam-scanned (PBS) proton therapy, the advantage of the characteristic sharp dose fall-off after the Bragg Peak (BP) becomes a disadvantage if the BP positions of a plan's constituent pencil beams are shifted, eg.due to anatomical changes. Thus, for fractionated PBS proton therapy, accurate knowledge of the water equivalent path length (WEPL) of the traversed anatomy is critical. In this work we investigate the feasibility of using 2D proton range maps (proton radiography, PR) with the active-scanning gantry at PSI...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048794/su-f-i-54-spatial-resolution-studies-in-proton-ct-using-a-phase-ii-prototype-head-scanner
#6
Tia E Plautz, R P Johnson, H F-W Sadrozinski, A Zatserklyaniy, V Bashkirov, R F Hurley, R W Schulte, P Piersimoni, V Giacometti
PURPOSE: To characterize the modulation transfer function (MTF) of the pre-clinical (phase II) head scanner developed for proton computed tomography (pCT) by the pCT collaboration. To evaluate the spatial resolution achievable by this system. METHODS: Our phase II proton CT scanner prototype consists of two silicon telescopes that track individual protons upstream and downstream from a phantom, and a 5-stage scintillation detector that measures a combination of the residual energy and range of the proton...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048753/su-f-i-32-organ-doses-from-pediatric-head-ct-scan
#7
H Liu, Q Liu, J Qiu, M Majer, Z Knezevic, S Miljanic, H Hrsak, W Zhuo
PURPOSE: To evaluate the organ doses of pediatric patients who undergoing head CT scan using Monte Carlo (MC) simulation and compare it with measurements in anthropomorphic child phantom.. METHODS: A ten years old children voxel phantom was developed from CT images, the voxel size of the phantom was 2mm*2mm*2mm. Organ doses from head CT scan were simulated using MCNPX software, 180 detectors were placed in the voxel phantom to tally the doses of the represented tissues or organs...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048685/tu-d-201-08-experience-complying-with-the-joint-commission-element-of-performance-on-radiation-dose-index-monitoring
#8
M P Supanich
PURPOSE: A new Joint Commission element of performance effective July 2015 requires incidents where the radiation dose index exceeds a defined level be reviewed, analyzed and compared to external benchmarks. This work offers a comprehensive review of the CT exams in which the notification level was exceeded and the reason at one academic medical center. This review may help other institutions set reference levels at clinically relevant values. METHODS: Radiation Dose Structured Reports from each of the 5 diagnostic CT scanners at our institution are automatically sent to our radiation dose index monitoring software platform, Radimetrics from Bayer Healthcare...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048590/we-ab-brb-03-real-time-volumetric-scintillation-dosimetry-for-radiation-therapy
#9
S Beddar
: Despite widespread IMRT treatments at modern radiation therapy clinics, precise dosimetric commissioning of an IMRT system remains a challenge. In the most recent report from the Radiological Physics Center (RPC), nearly 20% of institutions failed an end-to-end test with an anthropomorphic head and neck phantom, a test that has rather lenient dose difference and distance-to-agreement criteria of 7% and 4 mm. The RPC report provides strong evidence that IMRT implementation is prone to error and that improved quality assurance tools are required...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048491/su-f-sps-03-direct-measurement-of-organ-doses-resulting-from-head-and-cervical-spine-trauma-ct-protocols
#10
C Carranza, I Lipnharski, N Quails, N Correa, L Rill, M Arreola
PURPOSE: This retrospective study analyzes the exposure history of emergency department (ED) patients undergoing head and cervical spine trauma computed tomography (CT) studies. This study investigated dose levels received by trauma patients and addressed any potential concerns regarding radiation dose issues. METHODS: Under proper IRB approval, a cohort of 300 trauma cases of head and cervical spine trauma CT scans received in the ED was studied. The radiological image viewing software of the hospital was used to view patient images and image data...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048266/th-cd-207a-11-sensitivity-analysis-of-action-limits-for-real-time-epid-based-delivery-verification-system-using-artificial-clinical-relevant-error-simulations
#11
T Fuangrod, J Simpson, R Middleton, P Greer
PURPOSE: A real-time patient treatment delivery verification system using EPID (Watchdog) has been developed as an advanced patient safety tool. In a pilot study data was acquired for 119 prostate and head and neck (HN) IMRT patient deliveries to generate body-site specific action limits using statistical process control. The purpose of this study is to determine the sensitivity of Watchdog to detect clinically significant errors during treatment delivery. METHODS: Watchdog utilizes a physics-based model to generate a series of predicted transit cine EPID images as a reference data set, and compares these in real-time to measured transit cine-EPID images acquired during treatment using chi comparison (4%, 4mm criteria) after the initial 2s of treatment to allow for dose ramp-up...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048096/su-f-j-205-effect-of-cone-beam-factor-on-cone-beam-ct-number-accuracy
#12
W Yao, C Hua, J Farr, S Brady, T Merchant
PURPOSE: To examine the suitability of a Catphan™ 700 phantom for image quality QA of a cone beam computed tomography (CBCT) system deployed for proton therapy. METHODS: Catphan phantoms, particularly Catphan™ 504, are commonly used in image quality QA for CBCT. As a newer product, Catphan™ 700 offers more tissue equivalent inserts which may be useful for generating the electron density - CT number curve for CBCT based treatment planning. The sensitometry-and-geometry module used in Catphan™ 700 is located at the end of the phantom and after the resolution line pair module...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047989/tu-ab-bra-03-atlas-based-algorithms-with-local-registration-goodness-weighting-for-mri-driven-electron-density-mapping
#13
R Farjam, N Tyagi, H Veeraraghavan, A Apte, K Zakian, M Hunt, J Deasy
PURPOSE: To develop image-analysis algorithms to synthesize CT with accurate electron densities for MR-only radiotherapy of head & neck (H&N) and pelvis anatomies. METHODS: CT and 3T-MRI (Philips, mDixon sequence) scans were randomly selected from a pool of H&N (n=11) and pelvis (n=12) anatomies to form an atlas. All MRIs were pre-processed to eliminate scanner and patient-induced intensity inhomogeneities and standardize their intensity histograms. CT and MRI for each patient were then co-registered to construct CT-MRI atlases...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047926/we-ab-brb-04-cherenkov-imaging-for-radiation-therapy-dose-verification-on-patients
#14
B Pogue
: Despite widespread IMRT treatments at modern radiation therapy clinics, precise dosimetric commissioning of an IMRT system remains a challenge. In the most recent report from the Radiological Physics Center (RPC), nearly 20% of institutions failed an end-to-end test with an anthropomorphic head and neck phantom, a test that has rather lenient dose difference and distance-to-agreement criteria of 7% and 4 mm. The RPC report provides strong evidence that IMRT implementation is prone to error and that improved quality assurance tools are required...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047877/su-c-206-05-pixel-wise-calculation-of-noise-statistics-on-iterative-ct-reconstruction-from-a-single-scan
#15
T Wang, L Zhu
PURPOSE: As iterative CT reconstruction continues to advance, the spatial distributions of noise standard deviation (STD) and accurate noise power spectrum (NPS) on reconstructed CT images become more important for method evaluation ans algorithm parameters settings. Using data of a single scan, we propose a practical method for pixel-wise noise statistics calculation on iterative CT reconstruction image, which enables accurate calculation of noise STD for each pixel and NPS without stationary noise assumption...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047862/we-ab-brb-00-session-in-memory-of-robert-j-shalek-high-resolution-dosimetry-from-2d-to-3d-to-real-time-3d
#16
Harold Li
: Despite widespread IMRT treatments at modern radiation therapy clinics, precise dosimetric commissioning of an IMRT system remains a challenge. In the most recent report from the Radiological Physics Center (RPC), nearly 20% of institutions failed an end-to-end test with an anthropomorphic head and neck phantom, a test that has rather lenient dose difference and distance-to-agreement criteria of 7% and 4 mm. The RPC report provides strong evidence that IMRT implementation is prone to error and that improved quality assurance tools are required...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047789/su-g-iep2-13-toward-heavy-ion-computed-tomography-with-carbon-ions-a-monte-carlo-study
#17
D Shrestha, N Qin, Y Zhang, X Jia, J Wang
PURPOSE: In the present Monte Carlo study, we investigated the use of Carbon ions for computed tomography (CT) with a relatively low imaging dose. This will enable us to avoid any conversion of X-ray CT numbers to the relative stopping power (or relative electron density) values and the associated uncertainties in Carbon dose calculation. METHODS: In the first stage, we studied the propagation of Carbon nuclei through a water phantom using the Geant4 specially to understand their lateral displacement inside the phantom...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047612/su-g-iep4-11-monitoring-tumor-growth-in-subcutaneous-murine-tumor-model-in-vivo-a-comparison-between-mri-and-small-animal-ct
#18
B Wang, W He, D Cvetkovic, L Chen, J Fan, C Ma
PURPOSE: The purpose of the study is to compare the volume measurement of subcutaneous tumors in mice with different imaging platforms, namely a GE MRI and a Sofie-Biosciences small animal CT scanner. METHODS: A549 human lung carcinoma cells and FaDu human head and neck squamous cell carcinoma cells were implanted subcutaneously into flanks of nude mice. Three FaDu tumors and three A549 tumors were included in this study. The MRI scans were done with a GE Signa 1...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047551/su-g-206-05-a-comparison-of-head-phantoms-used-for-dose-determination-in-imaging-procedures
#19
Z Xiong, S Vijayan, J Kilian-Meneghin, S Rudin, D Bednarek
PURPOSE: To determine similarities and differences between various head phantoms that might be used for dose measurements in diagnostic imaging procedures. METHODS: We chose four frequently used anthropomorphic head phantoms (SK-150, PBU-50, RS-240T and Alderson Rando), a computational patient phantom (Zubal) and the CTDI head phantom for comparison in our study. We did a CT scan of the head phantoms using the same protocol and compared their dimensions and CT numbers...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047537/su-f-j-210-a-preliminary-study-on-the-dosimetric-impact-of-detector-based-spectral-ct-on-proton-therapy-treatment-planning
#20
C Cheng, S Lee, R Muzic, B Wessels, F Jesseph, R Ellis, D Mansur, A Dhanantwari
PURPOSE: To compare the difference in Hounsfield unit-relative stopping power and evaluate the dosimetric impact of spectral vs. conventional CT on proton therapy treatment plans. METHOD: The Philips prototype (IQon), a detector-based, spectral CT system (spectral) was used to scan calibration and Rando phantoms. Data were reconstructed with and without energy decomposition to produce monoenergetic 70 keV, 140 keV, and the Zeff images. Relative stopping power (RSP) in the head and lung regions were evaluated as a function of HU in order to compare spectral and conventional CT...
June 2016: Medical Physics
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