scholarly journals Investigating the Effect of Air Cavities of Sinuses on the Radiotherapy Dose Distribution Using Monte Carlo Method

2019 ◽  
Vol 9 (1Feb) ◽  
Author(s):  
F Seif ◽  
M R Bayatiani ◽  
S Hamidi ◽  
M Kargaran
Keyword(s):  
Monte Carlo ◽  
Dose Distribution ◽  
Sphenoid Sinus ◽  
Neck Region ◽  
Cavity Size ◽  
Air Cavity ◽  
Head And Neck Region ◽  
Radiotherapy Dose ◽  
Dose Deposition ◽  
Air Cavities

Background: Considering that some vital organs exist in the head and neck region, the treatment of tumors in this area is a crucial task. The existence of air cavities, namely sinuses, disrupt the radiotherapy dose distribution. The study aims to analyze the effect of maxillary, frontal, ethmoid and sphenoid sinuses on radiotherapy dose distribution by Monte Carlo method.Materials and Methods: In order to analyze the effect of the cavities on dose distribution, the maxillary, frontal, ethmoid and sphenoid sinus cavities were simulated with (3×3.2×2) cm3, (2×2×3.2) cm3, (1×1×1.2) cm3 and(1×1×2) cm3 dimensions.Results: In the analysis of the dose distribution caused by cavities, some parameters were observed, including: inhomogeneity of dose distribution in the cavities, inhomogeneity of dose on the edges of the air cavities and dispersion of the radiations after the air cavity. The amount of the dose in various situations showed differences: before the cavity a 0.64% and a 2.76% decrease, a 12.06% and a 17.17% decrease in the air zone, and a 2.25% and a 5.9% increase after the cavity.Conclusion: The results indicate that a drop in dose before the air cavities and in the air zone occurs due to the lack of scattered radiation. Furthermore, the rise in dose was due to the passage of more radiation from the air cavity and dose deposition after the air cavity. The changes in dose distribution are dependent on the cavity size and depth. As a result, this has to be noted in the treatment planning and MU calculations of the patient.

scholarly journals Investigating the Effect of Air Cavities of Sinuses on the Radiotherapy Dose Distribution Using Monte Carlo Method

2019 ◽  
Vol 9 (1Feb) ◽  
Author(s):  
F Seif ◽  
M R Bayatiani ◽  
S Hamidi ◽  
M Kargaran
Keyword(s):  
Monte Carlo ◽  
Dose Distribution ◽  
Sphenoid Sinus ◽  
Neck Region ◽  
Cavity Size ◽  
Air Cavity ◽  
Head And Neck Region ◽  
Radiotherapy Dose ◽  
Dose Deposition ◽  
Air Cavities

Background: Considering that some vital organs exist in the head and neck region, the treatment of tumors in this area is a crucial task. The existence of air cavities, namely sinuses, disrupt the radiotherapy dose distribution. The study aims to analyze the effect of maxillary, frontal, ethmoid and sphenoid sinuses on radiotherapy dose distribution by Monte Carlo method.Materials and Methods: In order to analyze the effect of the cavities on dose distribution, the maxillary, frontal, ethmoid and sphenoid sinus cavities were simulated with (3×3.2×2) cm3, (2×2×3.2) cm3, (1×1×1.2) cm3 and(1×1×2) cm3 dimensions.Results: In the analysis of the dose distribution caused by cavities, some parameters were observed, including: inhomogeneity of dose distribution in the cavities, inhomogeneity of dose on the edges of the air cavities and dispersion of the radiations after the air cavity. The amount of the dose in various situations showed differences: before the cavity a 0.64% and a 2.76% decrease, a 12.06% and a 17.17% decrease in the air zone, and a 2.25% and a 5.9% increase after the cavity.Conclusion: The results indicate that a drop in dose before the air cavities and in the air zone occurs due to the lack of scattered radiation. Furthermore, the rise in dose was due to the passage of more radiation from the air cavity and dose deposition after the air cavity. The changes in dose distribution are dependent on the cavity size and depth. As a result, this has to be noted in the treatment planning and MU calculations of the patient.

scholarly journals Effect of dental restorations and prostheses on radiotherapy dose distribution: a Monte Carlo study

2009 ◽  
Vol 10 (1) ◽  
pp. 80-89 ◽  
Author(s):  
David W. H. Chin ◽  
Nathaniel Treister ◽  
Bernard Friedland ◽  
Robert A. Cormack ◽  
Roy B. Tishler ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Dose Distribution ◽  
Monte Carlo Study ◽  
Dental Restorations ◽  
Radiotherapy Dose

scholarly journals Dosimetric Effects of Air Cavities for MRI-Guided Online Adaptive Radiation Therapy (MRgART) of Prostate Bed after Radical Prostatectomy

2022 ◽  
Vol 11 (2) ◽  
pp. 364
Author(s):  
Jonathan Pham ◽  
Minsong Cao ◽  
Stephanie M. Yoon ◽  
Yu Gao ◽  
Amar U. Kishan ◽  
...  
Keyword(s):  
Radiation Therapy ◽  
Electron Density ◽  
Deformable Registration ◽  
Imrt Plan ◽  
Cavity Size ◽  
Air Cavity ◽  
Prostate Bed ◽  
Density Map ◽  
Air Cavities ◽  
Electron Density Map

Purpose: To evaluate dosimetric impact of air cavities and their corresponding electron density correction for 0.35 tesla (T) Magnetic Resonance-guided Online Adaptive Radiation Therapy (MRgART) of prostate bed patients. Methods: Three 0.35 T MRgRT plans (anterior–posterior (AP) beam, AP–PA beams, and clinical intensity modulated radiation therapy (IMRT)) were generated on a prostate bed patient’s (Patient A) planning computed tomography (CT) with artificial rectal air cavities of various sizes (0–3 cm, 0.5 cm increments). Furthermore, two 0.35 T MRgART plans (‘Deformed’ and ‘Override’) were generated on a prostate bed patient’s (Patient B) daily magnetic resonance image (MRI) with artificial rectal air cavities of various sizes (0–3 cm, 0.5 cm increments) and on five prostate bed patient’s (Patient 1–5) daily MRIs (2 MRIs: Fraction A and B) with real air cavities. For each MRgART plan, daily MRI electron density map was obtained by deformable registration with simulation CT. In the ‘Deformed’ plan, a clinical IMRT plan is calculated on the daily MRI with electron density map obtained from deformable registration only. In the ‘Override’ plan, daily MRI and simulation CT air cavities are manually corrected and bulk assigned air and water density on the registered electron density map, respectively. Afterwards, the clinical IMRT plan is calculated. Results: For the MRgRT plans, AP and AP–PA plans’ rectum/rectal wall max dose increased with increasing air cavity size, where the 3 cm air cavity resulted in a 20%/17% and 13%/13% increase, relative to no air cavity, respectively. Clinical IMRT plan was robust to air cavity size, where dose change remained less than 1%. For the MRgART plans, daily MRI electron density maps, obtained from deformable registration with simulation CT, was unable to accurately produce electron densities reflecting the air cavities. However, for the artificial daily MRI air cavities, dosimetric change between ‘Deformed’ and ‘Override’ plan was small (<4%). Similarly, for the real daily MRI air cavities, clinical constraint changes between ‘Deformed’ and ‘Override’ plan was negligible and did not lead to change in clinical decision for adaptive planning except for two fractions. In these fractions, the ‘Override’ plan indicated that the bladder max dose and rectum V35.7 exceeded the constraint, while the ‘Deformed’ plan showed acceptable dose, although the absolute difference was only 0.3 Gy and 0.03 cc, respectively. Conclusion: Clinical 0.35 T IMRT prostate bed plans are dosimetrically robust to air cavities. MRgART air cavity electron density correction shows clinically insignificant change and is not warranted on low-field systems.

scholarly journals Investigating the Impact of Knee Prosthesis in Patients’ Body on Radiation Dose Distribution: A Monte Carlo Approach

2019 ◽  
Author(s):  
M R Bayatiani ◽  
F Seif ◽  
S Hamidi ◽  
S Bagheri
Keyword(s):  
Monte Carlo ◽  
Titanium Alloy ◽  
Dose Reduction ◽  
Alloy Steel ◽  
Dose Distribution ◽  
Knee Prosthesis ◽  
Cobalt Chromium ◽  
Radiotherapy Dose ◽  
Cobalt Chromium Molybdenum ◽  
The Impact

Introduction: Metal prostheses in patients affect the radiotherapy dose distribution. Metal prostheses with high density and atomic number cause major changes in scattering and attenuation of radiation. The present study aims to assess the impact of metal knee prosthesis with various dimensions and materials on radiotherapy dose distribution. Material and Methods: In this research, the Varian Linac and water phantom were simulated using the MCNPX code. Dose distribution of photon beam in a water phantom, with and without the presence of knee prostheses made of cobalt-chromium-molybdenum alloy, steel, titanium, and titanium alloy used in men and women was investigated using the Monte Carlo simulation.Results: The prosthesis led to an increase in dose in comparison with cases that there was used no prosthesis. According to values of the depth dose percentage, the maximum dose increase was found to be 6.8%, 6.1%, 4%, and 4.29%, and dose reduction 41.18%, 40.66%, 37.76%, and 37.51% for prosthetics with men’s knee dimensions made of cobalt-chromium-molybdenum alloy, steel, titanium alloy, and titanium, respectively. Above all, does increasing to 6.4%, 5.9%, 3.8%, and 3.94% and doses reducing to 40.87%, 40.36%, 36.94%, and 36.69 were observed in prosthetics for women. The highest amount of dose reduction for men’s prostheses made of mentioned materials was found to be 48.75%, 47.7%, 45%, and 45.8%, respectively. In addition, it was 46.36%, 45.8%, 43.8%, and 43.95% for women’s prostheses, respectively.Conclusion: Material will have a significant impact if a part of the knee bone places behind the prosthesis. According to the obtained values, it is recommended to utilize prostheses made of titanium and titanium alloys for knee arthroplasty. The prosthesis can either increase or decrease dose in tumor or lead to increase dose at organs at risk.

Monte Carlo as a tool to evaluate the effect of different lung densities on radiotherapy dose distribution

2014 ◽  
Vol 162 (1-2) ◽  
pp. 115-119 ◽  
Author(s):  
B. Caccia ◽  
C. Andenna ◽  
G. Iaccarino ◽  
V. Landoni ◽  
A. Soriani ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Dose Distribution ◽  
Radiotherapy Dose

scholarly journals Myxofibrosarcoma of the sphenoid sinus

2002 ◽  
Vol 116 (6) ◽  
pp. 464-466 ◽  
Author(s):  
Paul K. Y. Lam ◽  
Nigel Trendell-Smith ◽  
Jimmy H. C. Li ◽  
Y. W. Fan ◽  
Anthony P. W. Yuen
Keyword(s):  
Head And Neck ◽  
Malignant Fibrous Histiocytoma ◽  
Sphenoid Sinus ◽  
Fibrous Histiocytoma ◽  
Neck Region ◽  
Accurate Diagnosis ◽  
Close Collaboration ◽  
Rare Tumour ◽  
Head And Neck Region ◽  
Sphenoid Sinuses

Myxofibrosarcoma was originally described as the myxoid variant of malignant fibrous histiocytoma (MFH). It is uncommon in the head and neck region. We hereby report a case of myxofibrosarcoma in the sphenoid sinuses. The diagnostic and management difficulties are discussed. Close collaboration between surgeon, radiologist, histopathologist and clinical oncologist in making accurate diagnosis and appropriate management of this rare tumour are emphasized.

Đánh giá ảnh hưởng của hốc khí và trường chiếu nhỏ tới phân bố liều của kế hoạch JO - IMRT trên bệnh nhân ung thư đầu cổ bằng phương pháp MONTE CARLO

2020 ◽  
Author(s):  
Oanh Luong Thi
Keyword(s):  
Monte Carlo ◽  
Head And Neck ◽  
Dose Distribution ◽  
Interface Region ◽  
Field Size ◽  
Imrt Plan ◽  
Air Cavity ◽  
Study Results ◽  
Tissue Interface ◽  
Dose Reductions

Purposes: The goal of this study was to use Monte Carlo (MC) simulation to examine the dosimetric effects of the air cavity on JO-IMRT dose distribution at air-tissues interfaces in head-and-neck (H&N) patients. Methods: The EGSnrc - MC code system was used to calculate the dose reductions in air-tissue interface region for single field irradiations with 1×1, 2×2, 3×3, 4×4, and 5×5 cm2 in solid acrylic phantoms (30×30×20 cm3) and seven fields in a JO-IMRT plan. With phantom, the PDD values in both with and without an air cavity (15×4×4 cm3) which is 2.5 cm away from the anterior surface of phantom were used to evaluate. With the JO-IMRT plan, the dose-volume histograms (DVH), slice by slice isodose, and the gamma index using global methods implemented in PTW-VeriSoft with 3%/3 mm criteria were used to evaluate. Results: The study results indicate that the dose reductions in the air-tissue interface region of the phantom are strongly dependent on field size. The average percentage dose reductions at 1 mm from the air‑water interface for the field size 1×1, 2×2, 3×3, 4×4, and 5×5 cm2 are 62.04%, 52.34%, 40.71%, 26.72%, and 19.85%, respectively. Additionally, the mean MC dose in the PTV (65.58 Gy) of patients were lower than the TPS predicted dose (71.41 Gy). Conclusions: From this study, we conclude that the dose reduction in near air-tissue interfaces is a significant effect on JO-IMRT dose distribution in head-and-neck (H&N) patients.

Sign in / Sign up

Export Citation Format

Share Document