scholarly journals A Simple Scatter Reduction Method in Cone-Beam Computed Tomography for Dental and Maxillofacial Applications Based on Monte Carlo Simulation

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Chalinee Thanasupsombat ◽  
Saowapak S. Thongvigitmanee ◽  
Sorapong Aootaphao ◽  
Pairash Thajchayapong
Keyword(s):  
Computed Tomography ◽  
Monte Carlo ◽  
Cone Beam Computed Tomography ◽  
Cone Beam ◽  
Projection Data ◽  
Large Area ◽  
X Ray ◽  
X Ray Scattering ◽  
Scatter Reduction ◽  
Ray Scattering

The quality of images obtained from cone-beam computed tomography (CBCT) is important in diagnosis and treatment planning for dental and maxillofacial applications. However, X-ray scattering inside a human head is one of the main factors that cause a drop in image quality, especially in the CBCT system with a wide-angle cone-beam X-ray source and a large area detector. In this study, the X-ray scattering distribution within a standard head phantom was estimated using the Monte Carlo method based on Geant4. Due to small variation of low-frequency scattering signals, the scattering signals from the head phantom can be represented as the simple predetermined scattering signals from a patient’s head and subtracted the projection data for scatter reduction. The results showed higher contrast and less cupping artifacts on the reconstructed images of the head phantom and real patients. Furthermore, the same simulated scattering signals can also be applied to process with higher-resolution projection data.

A feasibility study of time of flight cone beam computed tomography imaging

2021 ◽  
pp. 1-14
Author(s):  
Ignacio O. Romero ◽  
Changqing Li
Keyword(s):  
Computed Tomography ◽  
Cone Beam Computed Tomography ◽  
Time Of Flight ◽  
Cone Beam ◽  
X Ray ◽  
X Ray Scattering ◽  
Scattering Effects ◽  
Breast Phantom ◽  
Scatter Reduction ◽  
Strong Scattering

BACKGROUND: The time of flight (TOF) cone beam computed tomography (CBCT) was recently shown to reduce the X-ray scattering effects by 95%and improve the image CNR by 110%for large volume objects. The advancements in X-ray sources like in compact Free Electron Lasers (FEL) and advancements in detector technology show potential for the TOF method to be feasible in CBCT when imaging large objects. OBJECTIVE: To investigate feasibility and efficacy of TOF CBCT in imaging smaller objects with different targets such as bones and tumors embedded inside the background. METHODS: The TOF method used in this work was verified using a 24cm phantom. Then, the GATE software was used to simulate the CBCT imaging of an 8 cm diameter cylindrical water phantom with two bone targets using a modeled 20 keV quasi-energetic FEL source and various TOF resolutions ranging from 1 to 1000 ps. An inhomogeneous breast phantom of similar size with tumor targets was also imaged using the same system setup. RESULTS: The same results were obtained in the 24cm phantom, which validated the applied CBCT simulation approach. For the case of 8cm cylindrical phantom and bone target, a TOF resolution of 10 ps improved the image contrast-to-noise ratio (CNR) by 57%and reduced the scatter-to-primary ratio (SPR) by 8.63. For the case of breast phantom and tumor target, image CNR was enhanced by 12%and SPR was reduced by 1.35 at 5 ps temporal resolution. CONCLUSIONS: This study indicates that a TOF resolution below 10 ps is required to observe notable enhancements in the image quality and scatter reduction for small objects around 8cm in diameter. The strong scattering targets such as bone can result in substantial improvements by using TOF CBCT.

Monte Carlo dose Assessment in Dental Cone-Beam Computed Tomography

2021 ◽  
Author(s):  
Jinwoo Kim ◽  
Hosang Jeon ◽  
Ho Kyung Kim
Keyword(s):  
Computed Tomography ◽  
Monte Carlo ◽  
Cone Beam Computed Tomography ◽  
Patient Dose ◽  
Mode Analysis ◽  
Cone Beam ◽  
Tube Voltage ◽  
X Ray ◽  
Wide Range ◽  
Detector Geometry

Abstract Most dental cone-beam computed tomography (CBCT) uses an x-ray beam field covering the maxillomandibular region and the width-truncated detector geometry. The spatial dose distribution in dental CBCT is analyzed in terms of local primary and remote secondary doses by using a list-mode analysis of x-ray interactions obtained from the Monte Carlo simulations. The patient-dose benefit due to the width-truncated detector geometry is also investigated for a wide range of detector offsets. The developed dose estimation agrees with the measurement in a relative error of 7.7%. The secondary dose outside of the irradiation field becomes larger with increasing tube voltage. The dose benefit with the width-truncated geometry linearly increases as the detector-offset width is decreased. Leaving the CT image quality out of the account, the MC results reveal that the operation of dental CBCT with a lower tube voltage and a smaller detector-offset width is beneficial to the patient dose.

Workflow-Based Design and Evaluation of a Device for CBCT-Guided Biopsy

2021 ◽  
Vol 15 (3) ◽  
Author(s):  
A. Pfeil ◽  
L. Barbé ◽  
F. Geiskopf ◽  
R. L. Cazzato ◽  
P. Renaud
Keyword(s):  
Computed Tomography ◽  
Remote Control ◽  
Cone Beam Computed Tomography ◽  
Added Value ◽  
Cone Beam ◽  
X Ray ◽  
Novel Device ◽  
Robotic Devices ◽  
Mechanical Devices ◽  
Personalized Cancer

Abstract Biopsies for personalized cancer care can be performed with cone beam computed tomography (CBCT) guidance, but manual needle manipulation remains an issue due to X-ray exposure to physicians. Modern CBCT scanners integrate today real-time imaging and software assistance for needle planning. In this paper, these available features are exploited to design a novel device offering an intermediate level of assistance between simple passive mechanical devices of limited efficiency, and advanced robotic devices requiring adapted procedure workflows. Our resulting system is built to limit its impact on the current manual practice. It is patient-mounted and provides remote control of needle orientation and insertion. A multilayer phantom is specifically developed to reproduce interactions between the needle and soft abdominal tissues. It is used to experimentally evaluate the device added value by comparing assisted versus manual needle insertions. The device is shown to help reducing X-ray exposure by a factor 4, without impacting the accuracy obtained manually.

scholarly journals Dispersion of Silica Particles in Rubber During Elongation Revealed by Ultra Small Angle X-ray Scattering and Reverse Monte Carlo Modelling

2019 ◽  
Vol 92 (4) ◽  
pp. 152-157
Author(s):  
Tomotaka NAKATANI ◽  
Shinji KOHARA ◽  
Taiki HOSHINO ◽  
So FUJINAMI ◽  
Masaki TAKATA
Keyword(s):  
Monte Carlo ◽  
Small Angle ◽  
Silica Particles ◽  
Reverse Monte Carlo ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering
Sign in / Sign up

Export Citation Format

Share Document