scholarly journals Early experience with four-dimensional computed tomography for observing velopharyngeal closure function in pediatric patients and the evaluation of the exposure dose

2020 ◽  
Author(s):  
Yoshikazu Kobayashi ◽  
Masanao Kobayashi ◽  
Daisuke Kanamori ◽  
Naoko Fujii ◽  
Yumi Kataoka ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Cleft Palate ◽  
Pediatric Patients ◽  
Velopharyngeal Insufficiency ◽  
Absorbed Doses ◽  
Study Results ◽  
Velopharyngeal Closure ◽  
Closure Function

Abstract Background The aims of this study were to perform a four-dimensional assessment of velopharyngeal closure function in pediatric patients with cleft palate using 320-row area detector computed tomography (CT), and to estimate the organ-absorbed doses using Monte Carlo simulation. Methods We evaluated CT image data obtained between July 2018 and August 2019 from five pediatric patients with cleft palate (four boys and one girl; age range, 4–7 years) at Fujita Health University Hospital. The presence of velopharyngeal insufficiency (VPI), patterns of velopharyngeal closure (VPC), and cross-sectional area of VPI were evaluated. In addition, organ-absorbed doses were assumed in the Monte Carlo simulation. However, we did not perform statistical analysis because of the insufficient number of patients enrolled in this study. Results The existence of VPI and hypernasality were completely concordant. The VPC patterns were circular (two patients), circular with Passavant’s ridge (one patient), and unevaluable (two patients). The organ-absorbed doses were relatively lower than those in past reports. Conclusions Our method could be an alternative for patients who refuse the conventional nasopharyngoscopic evaluation.

Evaluation of Velopharyngeal Closure Function With 4-Dimensional Computed Tomography and Assessment of Radiation Exposure in Pediatric Patients: A Cross-Sectional Study

2021 ◽  
pp. 105566562110017
Author(s):  
Yoshikazu Kobayashi ◽  
Masanao Kobayashi ◽  
Daisuke Kanamori ◽  
Naoko Fujii ◽  
Yumi Kataoka ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Radiation Exposure ◽  
Exposure Dose ◽  
Velopharyngeal Insufficiency ◽  
Radiation Doses ◽  
Secondary Surgery ◽  
Cross Sectional ◽  
Computed Tomography Images ◽  
Velopharyngeal Closure ◽  
Closure Function

Objective: Some patients with cleft palate (CP) need secondary surgery to improve functionality. Although 4-dimensional assessment of velopharyngeal closure function (VPF) in patients with CP using computed tomography (CT) has been existed, the knowledge about quantitative evaluation and radiation exposure dose is limited. We performed a qualitative and quantitative assessment of VPF using CT and estimated the exposure doses. Design: Cross-sectional. Setting: Computed tomography images from 5 preoperative patients with submucous CP (SMCP) and 10 postoperative patients with a history of CP (8 boys and 7 girls, aged 4-7 years) were evaluated. Patients: Five patients had undergone primary surgery for SMCP; 10 received secondary surgery for hypernasality. Main Outcome Measures: The presence of velopharyngeal insufficiency (VPI), patterns of velopharyngeal closure (VPC), and cross-sectional area (CSA) of VPI was evaluated via CT findings. Organ-absorbed radiation doses were estimated in 5 of 15 patients. The differences between cleft type and VPI, VPC patterns, and CSA of VPI were evaluated. Results: All patients had VPI. The VPC patterns (SMCP/CP) were evaluated as coronal (1/4), sagittal (0/1), circular (1/2), and circular with Passavant’s ridge (2/2); 2 patients (1/1) were unevaluable because of poor VPF. The CSA of VPI was statistically larger in the SMCP group ( P = .0027). The organ-absorbed radiation doses were relatively lower than those previously reported. Conclusions: Four-dimensional CT can provide the detailed findings of VPF that are not possible with conventional CT, and the exposure dose was considered medically acceptable.

scholarly journals Radiation doses in cone-beam breast computed tomography: A Monte Carlo simulation study

2011 ◽  
Vol 38 (2) ◽  
pp. 589-597 ◽  
Author(s):  
Ying Yi ◽  
Chao-Jen Lai ◽  
Tao Han ◽  
Yuncheng Zhong ◽  
Youtao Shen ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Simulation Study ◽  
Cone Beam ◽  
Radiation Doses ◽  
Monte Carlo Simulation Study ◽  
Breast Computed Tomography

Monte Carlo Simulation of the Computed Tomography Dose Index (CTDI) Using GATE

2020 ◽  
Vol 17 (6) ◽  
pp. 900-907
Author(s):  
M. Mkimel ◽  
R. El Baydaoui ◽  
M. R. Mesradi ◽  
Z. Tahiri ◽  
K. Talasmat ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Computed Tomography Dose Index ◽  
Dose Index

scholarly journals Monte Carlo Simulation for Polychromatic X-Ray Fluorescence Computed Tomography with Sheet-Beam Geometry

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Shanghai Jiang ◽  
Peng He ◽  
Luzhen Deng ◽  
Mianyi Chen ◽  
Biao Wei
Keyword(s):  
Computed Tomography ◽  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Expectation Maximization ◽  
Huge Amount ◽  
X Ray ◽  
Beam Geometry ◽  
Weight Concentration ◽  
Imaging Model ◽  
Maximum Likelihood Expectation Maximization

X-ray fluorescence computed tomography (XFCT) based on sheet beam can save a huge amount of time to obtain a whole set of projections using synchrotron. However, it is clearly unpractical for most biomedical research laboratories. In this paper, polychromatic X-ray fluorescence computed tomography with sheet-beam geometry is tested by Monte Carlo simulation. First, two phantoms (A and B) filled with PMMA are used to simulate imaging process through GEANT 4. Phantom A contains several GNP-loaded regions with the same size (10 mm) in height and diameter but different Au weight concentration ranging from 0.3% to 1.8%. Phantom B contains twelve GNP-loaded regions with the same Au weight concentration (1.6%) but different diameter ranging from 1 mm to 9 mm. Second, discretized presentation of imaging model is established to reconstruct more accurate XFCT images. Third, XFCT images of phantoms A and B are reconstructed by filter back-projection (FBP) and maximum likelihood expectation maximization (MLEM) with and without correction, respectively. Contrast-to-noise ratio (CNR) is calculated to evaluate all the reconstructed images. Our results show that it is feasible for sheet-beam XFCT system based on polychromatic X-ray source and the discretized imaging model can be used to reconstruct more accurate images.

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