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Cone beam CT

Julia Mascolo-Fortin, Dmitri Matenine, Louis Archambault, Philippe Després
BACKGROUND: Four-dimensional cone beam computed tomography allows for temporally resolved imaging with useful applications in radiotherapy, but raises particular challenges in terms of image quality and computation time. OBJECTIVE: The purpose of this work is to develop a fast and accurate 4D algorithm by adapting a GPU-accelerated ordered subsets convex algorithm (OSC), combined with the total variation minimization regularization technique (TV). METHODS: Different initialization schemes were studied to adapt the OSC-TV algorithm to 4D reconstruction: each respiratory phase was initialized either with a 3D reconstruction or a blank image...
March 15, 2018: Journal of X-ray Science and Technology
Claudio Agostinelli, Agnese Agostinelli, Marco Berardini, Paolo Trisi
PURPOSE: The aim of the present study was to analyze the alveolar bone morphology of the upper first and second molars. This analysis aims to evaluate the morphology of a hypothetical postextractive site in the upper molar area to diagnose the possibility of immediate postextraction implant placement. MATERIALS AND METHODS: Cone-beam CT scans of 100 patients were examined. The measurements were made using a dedicated 3D software. Reference points were identified to allow clear and repeatable measurements...
March 19, 2018: Implant Dentistry
K Mohamathu Rafic, S Amalan, B S Timothy Peace, B Paul Ravindran
Background and aim: The practicability of computing dose calculation on cone beam CT (CBCT) has been widely investigated. In most clinical scenarios, the craniocaudal scanning length of CBCT is found to be inadequate for localization. This study aims to explore extended tomographic localization and adaptive dose calculation strategies using Hounsfield unit (HU) corrected CBCT image sets. Materials and methods: Planning CT (pCT) images of the Rando phantom (T12 -to-midthigh) were acquired with pelvic-protocol using Biograph CT-scanner...
March 2018: Reports of Practical Oncology and Radiotherapy
Shi Kang Wong, Pravinkumar G Patil
STATEMENT OF PROBLEM: The inferior alveolar nerve (IAN) frequently loops backward before exiting from the mental foramen and spreads several millimeters medially to the foramen. Implant placement in this area may damage the nerve if the anterior loop area is not carefully identified in a radiographic or computed tomography (CT) evaluation. PURPOSE: The purpose of this observational study was to measure the prevalence of the presence of the anterior loop and to estimate sex and ethnicity-related variations in anterior loop length in the Malaysian population...
March 15, 2018: Journal of Prosthetic Dentistry
Kurtis H Dekker, Rubin Hazarika, Matheus A Silveira, Kevin J Jordan
Optical cone beam computed tomography (CT) scanning of radiochromic gel dosimeters, using a CCD camera and a low stray light convergent source, provides fast, truly 3D radiation dosimetry with high accuracy. However, a key limiting factor in radiochromic gel dosimetry at large (⩾10 cm diameter) volumes is the initial attenuation of the dosimeters. It is not unusual to observe a 5-10×  difference in signal intensity through the dosimeter center versus through the surrounding medium in pre-irradiation images...
March 16, 2018: Physics in Medicine and Biology
Minah Han, Byeongjoon Kim, Jongduk Baek
We investigate the detectability of breast cone beam computed tomography images using human and model observers and the variations of exponent, β, of the inverse power-law spectrum for various reconstruction filters and interpolation methods in the Feldkamp-Davis-Kress (FDK) reconstruction. Using computer simulation, a breast volume with a 50% volume glandular fraction and a 2mm diameter lesion are generated and projection data are acquired. In the FDK reconstruction, projection data are apodized using one of three reconstruction filters; Hanning, Shepp-Logan, or Ram-Lak, and back-projection is performed with and without Fourier interpolation...
2018: PloS One
John W Garrett, Yinsheng Li, Ke Li, Guang-Hong Chen
PURPOSE: Digital breast tomosynthesis (DBT) has been shown to somewhat alleviate the breast tissue overlapping issues of two dimensional (2D) mammography.However, the improvement in current DBT systems over mammography is still limited.Statistical image reconstruction (SIR) methods have the potential to reduce through-plane artifacts in DBT, and thus may be used to further reduce anatomical clutter. The purpose of this work was to study the impact of SIR on anatomical clutter in the reconstructed DBT image volumes...
March 15, 2018: Medical Physics
Nathan Cho, Panagiotis Tsiamas, Esteban Velarde, Erik Tryggestad, Robert Jacques, Ross Berbeco, Todd McNutt, Peter Kazanzides, John Wong
PURPOSE: The Small Animal Radiation Research Platform (SARRP) has been developed for conformal micro irradiation with on-board cone-beam CT (CBCT) guidance. The graphics processing unit (GPU)-accelerated Superposition-Convolution (SC) method for dose computation has been integrated into the treatment planning system (TPS) for SARRP. This paper describes the validation of the SC method for the kilovoltage energy by comparing with EBT2 film measurements and Monte Carlo (MC) simulations...
March 15, 2018: Medical Physics
Georg Böning, Willie M Lüdemann, Julius Chapiro, Martin Jonczyk, Bernd Hamm, Rolf W Günther, Bernhard Gebauer, Florian Streitparth
PURPOSE: The aim of this study was to evaluate the feasibility of cone-beam computed tomography (CBCT)-based real-time 3-D guidance of TIPSS placement and its positioning compared to standard guiding methods. MATERIALS AND METHODS: In a prospective, randomized, consecutive study design from 2015 to 2017, we included 21 patients in the CBCT guided group and 15 patients in the ultrasound (US) guided group. The prospective groups were compared in terms of success rate of intervention, portal vein puncture/procedure time, number of puncture attempts and applied dose...
March 14, 2018: Cardiovascular and Interventional Radiology
Robyn Melanie Benz, Meritxell Alzamora Garcia, Felix Amsler, Johannes Voigt, Andreas Fieselmann, Anna Lucja Falkowski, Bram Stieltjes, Anna Hirschmann
Phantom-based initial performance assessment of a prototype three-dimensional (3-D) x-ray system and comparison of 3-D tomography with computed tomography (CT) were proposed. A 3-D image quality phantom was scanned with a prototype version of 3-D cone-beam CT imaging implemented on a twin robotic x-ray system using three trajectories (163 deg = table, 188 deg = upright, and 200 deg = side), six tube voltages (60, 70, 81, 90, 100, and 121 kV), and four detector doses (0.348, 0.696, 1.740, and [Formula: see text])...
January 2018: Journal of Medical Imaging
Rubens Spin-Neto, Louise H Matzen, Lars W Schropp, Thomas S Sørensen, Ann Wenzel
OBJECTIVES: To assess the impact of head motion artefacts and an automated artefact-correction system on CBCT image quality and interpretability for simulated diagnostic tasks. METHODS: A partially dentate human skull was mounted on a robot simulating four types of head movement (antero-posterior translation, nodding, lateral rotation, and tremor), at three distances (0.75, 1.5, and 3 mm) based on two movement patterns (skull returning/not returning to the initial position)...
March 14, 2018: Dento Maxillo Facial Radiology
Mark C Lawlor, Melissa A Kluczynski, John M Marzo
BACKGROUND: The utility of computed tomography (CT) for measuring medial clear space (MCS) for determination of the stability of supination external rotation (SER) ankle fractures and in comparison to standard radiographs is unknown. We compared MCS on gravity stress (GS) radiographs to GS and weight bearing (WB) cone-beam CT (CBCT). METHODS: An AO SER 44B3.1 ankle fracture was simulated in 10 human cadavers, also serving as controls. MCS was measured on GS radiographs, GS CBCT, and a simulated WB CBCT scan...
March 1, 2018: Foot & Ankle International
John W Hayes, Daniel Gomez-Cardona, Ran Zhang, Ke Li, Juan Pablo Cruz-Bastida, Guang-Hong Chen
PURPOSE: Low signal correction (LSC) in the raw counts domain has been shown to effectively reduce noise streaks in CT because the data inconsistency associated with photon-starved regions may be mitigated prior to the log transformation step. However, a systematic study of the performance of these raw data correction methods is still missing in literature. The purpose of this work was to provide such a systematic study for two well-known low signal correction schemes using either the adaptive trimmed mean (ATM) filter or the anisotropic diffusion (AD) filter in the raw counts domain...
March 12, 2018: Medical Physics
Daniel Gomez-Cardona, John Hayes, Ran Zhang, Ke Li, Juan Pablo Cruz-Bastida, Guang-Hong Chen
PURPOSE: Different low signal correction (LSC) methods have been shown to efficiently reduce noise streaks and noise level in CT to provide acceptable images at low radiation dose levels. These methods usually result in CT images with highly shift-variant and anisotropic spatial resolution and noise, which makes the parameter optimization process highly nontrivial. The purpose of this work was to develop a local task-based parameter optimization framework for LSC methods. METHODS: Two well-known LSC methods: the adaptive trimmed mean (ATM) filter and the anisotropic diffusion (AD) filter, were used as examples to demonstrate how to use the task-based framework to optimize filter parameter selection...
March 12, 2018: Medical Physics
N P Shah, L Murtadha, J Brown
The aims of this study were to find the incidence of bifurcation of the inferior dental nerve (IDN) canal, to describe the characteristics of this variant, and to examine the sensitivity and specificity of dental panoramic tomography to identify it. We classified bifurcations by size and position relative to the main canal and the lower third molar using cone-beam computed tomography (CT) and dental panoramic tomography. In our study of 281 patients, 106 (38%) had bifurcations, and in one quarter, these were classified as large accessory canals...
March 7, 2018: British Journal of Oral & Maxillofacial Surgery
Dong Il Gwon, Gi-Young Ko, Young Baek Kwon, Hyun-Ki Yoon, Kyu-Bo Sung
Objective: To investigate the technical and clinical outcomes of plug-assisted retrograde transvenous obliteration (PARTO) for the treatment of gastric varices (GV) and to evaluate the role of intra-procedural cone-beam computed tomography (CBCT) performed during PARTO to confirm its technical success. Materials and Methods: From January 2016 to December 2016, 17 patients with GV who had undergone PARTO were retrospectively evaluated. When the proximal part of the afferent vein was identified on a fluoroscopy, non-contrast CBCT images were obtained...
March 2018: Korean Journal of Radiology: Official Journal of the Korean Radiological Society
Jie Wei, Ming Chao
PURPOSE: We presented a feasibility study to extract the diaphragm motion from the inferior contrast cone beam computed tomography (CBCT) projection images using a constrained linear regression optimization algorithm. METHODS: The shape of the diaphragm was fitted by a parabolic function which was initialized by five manually placed points on the diaphragm contour of a pre-selected projection. A constrained linear regression model by exploiting the spatial, algebraic, and temporal constraints of the diaphragm, approximated by a parabola, was employed to estimate the parameters...
February 2018: Physica Medica: PM
Cristina Garibaldi, Cristiana Fodor, Giulia Riva, Damaris Patricia Rojas, Samantha Dicuonzo, Elisa Pace, Giuseppe Fanetti, Paolo De Marco, Veronica Dell'acqua, Giulia Marvaso, Maria Cristina Leonardi, Roberta Lazzari, Federica Cattani, Marta Cremonesi, Roberto Orecchia, Barbara Alicja Jereczek-Fossa
PURPOSE: To evaluate inter-fraction tumor localization errors (TE) in the RapidArc® treatment of pelvic cancers based on CBCT. Appropriate CTV-to PTV margins in a non-IGRT scenario have been proposed. METHODS: Data of 928 patients with prostate, gynecological, and rectum/anal canal cancers were retrospectively analyzed to determine systematic and random localization errors. Two protocols were used: daily online IGRT (d-IGRT) and weekly IGRT. The latter consisted in acquiring a CBCT for the first 3 fractions and subsequently once a week...
February 2018: Physica Medica: PM
Mohammad Haekal, Hidetaka Arimura, Taka-Aki Hirose, Yusuke Shibayama, Saiji Ohga, Junichi Fukunaga, Yoshiyuki Umezu, Hiroshi Honda, Tomonari Sasaki
PURPOSE: To analyze the uncertainties of the rectum due to anisotropic shape variations by using a statistical point distribution model (PDM). MATERIALS AND METHODS: The PDM was applied to the rectum contours that were delineated on planning computed tomography (CT) and cone-beam CT (CBCT) at 80 fractions of 11 patients. The standard deviations (SDs) of systematic and random errors of the shape variations of the whole rectum and the region in which the rectum overlapped with the PTV (ROP regions) were derived from the PDMs at all fractions of each patient...
February 2018: Physica Medica: PM
Zhigui Ma, Haoming Zhao, Baoting Fan, Chi Yang, Minjie Chen, Shanyong Zhang
To evaluate the feasibility of the orthodontic traction after local resection of the condylar osteochondroma (OC).From November 2011 to September 2016, consecutive patients with condylar OC who underwent orthodontic extraction after local resection of the mass were reviewed. Clinical data and cone-beam computed tomography (CT) were obtained before treatment (T0), 1 week after surgery (T1), and at least 6-month follow-up after OC resection (T2). Repeated-measures analysis of variance with Bonferroni multiple-comparison test was used to compare the 3-dimensional cephalometric variables at different time points and the paired t test was used to compare changes of temporomandibular joint (TMJ) space between the 2 sides at T1 and T2...
March 2018: Medicine (Baltimore)
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