Search for: treatment-planning
M.Sc. Thesis Sharif University of Technology ; Najafi, Mehdi
Intensity Modulated Radiation Therapy is one of the most commonly used procedures of delivering radiation to cancerous tissues, with the aim of reaching the prescripted dose in the target volume while minimizing damage to nearby healthy organs. Two decisions are of fundamental importance: to select the beam angles and calculate the beam intensities. Beam Angle selection (Beam Angle Optimization) is an important problem. Due to the large amounts of computational time, beam angles are often selected manually based on human experience and intuition. In this study, three optimization methods –Simulated Annealing, Branch & Prune and Local Neighborhood Search- that are selected among known methods...
M.Sc. Thesis Sharif University of Technology ; Rafiee, Majid
external radiation therapy is a methods of cancer treatment or improvement of cancer-related complications. various techniques have been developed for external beam radiation therapy. Among which, Intensity Modulated Radiation Therapy (IMRT), due to its ability to adjust the intensity of radiation beams, has a higher capacity to generate appropriate dose distribution based on tumor size and volume. Intensity Modulated Radiation Therapy is one of the most commonly used procedures of delivering radiation to cancerous tissues, with the aim of reaching the prescripted dose in the target volume while minimizing damage to nearby healthy organs. Two decisions are of fundamental importance: to...
Exact Simulation of Varian Clinac 2100C/D with Use of Phase Space file and Representation of Appropriate Source Model for Clinical Applications, Ph.D. Dissertation Sharif University of Technology ; Sohrabpour, Mostafa ; Rabi Mahdavi, Saeed
MC Simulation is considered to be one of the most accurate methods for transport of radiation in various media. Computational speed is the limiting factor to apply the MC method in clinical settings. One of the methods to increase the speed in MC simulations is the use of phase space file (PSF). PSF is generated by transporting the particles through the linear accelerator head. The characteristics of these particles crossing a reference plane are stored in the PSF file. The PSF can be used in subsequent simulations as a radiation source. The use of PSF is effective but has a drawback of having latent variance. Latent variance is a problem inherent in using phase space files. Latent variance...
M.Sc. Thesis Sharif University of Technology ; Najafi, Mehdi
Intensity Modulated Radiation Therapy is one of the common methods for treating cancer patients because of the ability to transfer high doses of radiation to the tumor and minimize damage to surrounding healthy organs. In this method, the patient is placed in a special bed, while a linear accelerator directs the beams to radiation to the target's size. Patient treatment requires a unique treatment plan, and optimization of the treatment plan involves two basic decisions: (1) selecting the beam angles; (2) calculating the beams intensity. In the radiation therapy process, there are various uncertainty factors, such as patient setup, tumor volume definition, tumor growth or movement, and the...
M.Sc. Thesis Sharif University of Technology ; Rafiee, Majid
As a method of cancer treatment or improvement of cancer-related complications, external radiation therapy is prescribed by physicians, in case of detection of a tumor in a region of patient’s body. Over time, various techniques have been developed for external beam radiation therapy. Among which, Intensity Modulated Radiation Therapy (IMRT), due to its ability to adjust the intensity of radiation beams, has a higher capacity to generate appropriate dose distribution based on tumor size and volume and it is one of the most widely used techniques in cancer treatment centers.The core process in treatment planning is using appropriate computer algorithms which results in posing enough damage to...
M.Sc. Thesis Sharif University of Technology ; Najafi, Mehdi ; Rafiee, Majid
Nowadays, radiation therapy is one of the most common methods for the cancer treatment. Intensity Modulated Radiation Therapy(IMRT) is a novel technique of radiation therapy that aims to delivere sufficient dose to cancerous tissues while sparing healthy organs. There are various uncertainties in radiation therapy problems, including uncertainty about device setup, device errors, interfraction and intrafraction motions. One of the most important uncertainties is the movement of the tumor during the treatment process(intrafraction motion), as this displacement may cause the cancer tissue to not receive sufficient dose and also to damage the healthy tissue due to a violation of their dose...
M.Sc. Thesis Sharif University of Technology ; Rafiee, Majid ; Mahnam, Mehdi
Today, cancer is one of the leading causes of death globally, killing millions of people around the world every year. This indicates the need for more attention to the treatment of this disease. Cancer can be prevented from growing by being diagnosed at an early stage and choosing the proper treatment. Among cancer treatment methods, radiation therapy is one of the most widely used methods, and Intensity-Modulated Radiation Therapy (IMRT) is one of the most efficient and resilient methods of radiation therapy. In the IMRT treatment plan, the optimal choice of radiation intensity is of particular importance abd the mathematical modeling problems related to determining the intensity of beams...
High intensity focused ultrasound (HIFU) ablation of porous liver: numerical analysis of heat transfer and hemodynamics, Article Applied Thermal Engineering ; Volume 170 , April , 2020 ; Firoozabadi, B ; Sharif University of Technology
Elsevier Ltd 2020
In the present study, the influence of the liver vascular bed on heat transfer in a tumor located close to the hepatic artery and exposed to high intensity focused ultrasound (HIFU), is studied numerically. For this purpose, an acoustics-thermal-fluid coupling model based on the porous media theory under the local thermal non-equilibrium assumption is used to calculate the temperature field in the tumor, porous liver, and the hepatic artery. Different generations of the liver vasculature including arterial branches, terminal arterial branches, terminal veins and venous branches are examined at different porosities (the volume fraction of the vasculature). It is found that the liver...
Assessment and comparison of اomogeneity and conformity indexes in step-and-shoot and compensator-based intensity modulated radiation therapy (IMRT) and three-dimensional conformal radiation therapy (3D CRT) in prostate cancer, Article Journal of Medical Signals and Sensors ; Volume 7, Issue 2 , 2017 , Pages 102-107 ; 22287477 (ISSN) ; Shirani Tak Abi, K ; Nedaie, H. A ; Hassani, H ; Gharaati, H ; Samei, M ; Shahi, R ; Zarei, H ; Sharif University of Technology
Intensity modulated radiation therapy (IMRT) and three-dimensional conformal radiation therapy (3D CRT) are two treatment modalities in prostate cancer, which provide acceptable dose distribution in tumor region with sparing the surrounding normal tissues. IMRT is based on inverse planning optimization; in which, intensity of beams is modified by using multileaf collimators and also compensators with optimum shapes in step and shoot (SAS) and compensator-based method, respectively. In the recent study, some important parameters were compared in two IMRT and 3D CRT methods. Prescribed dose was 80 Gy for both IMRT procedures and 70 Gy for 3D CRT. Treatment plans of 15 prostate cancer...
Article Journal of Theoretical Biology ; Volume 236, Issue 3 , 2005 , Pages 311-322 ; 00225193 (ISSN) ; Sarbaz, Y ; Gharibzadeh, S ; Sharif University of Technology
In this paper, we discuss modeling issues of the Parkinson's tremor. Through the work we have employed physiological structure as well as functioning of the parts in brain that are involved in the disease. To obtain more practical similarity, random behaviors of the connection paths are also considered. Medication or treatment of the disease both by drug prescription and electrical signal stimulation are modeled based on the same model introduced for the disease itself. Two new medication strategies are proposed based on the model to reduce the side effects caused by the present drug prescription. © 2005 Elsevier Ltd. All rights reserved
Findings of DTI-p maps in comparison with T 2 /T 2 -FLAIR to assess postoperative hyper-signal abnormal regions in patients with glioblastoma 08 Information and Computing Sciences 0801 Artificial Intelligence and Image Processing, Article Cancer Imaging ; Volume 18, Issue 1 , 2018 ; 14707330 (ISSN) ; Safari, M ; Ameri, A ; Shojaee Moghadam, M ; Arbabi, A ; Tabatabaeefar, M ; Salighehrad, H ; Sharif University of Technology
BioMed Central Ltd 2018
Purpose: The aim of this study was to compare diffusion tensor imaging (DTI) isotropic map (p-map) with current radiographically (T 2/T 2 -FLAIR) methods based on abnormal hyper-signal size and location of glioblastoma tumor using a semi-automatic approach. Materials and methods: Twenty-five patients with biopsy-proved diagnosis of glioblastoma participated in this study. T 2, T 2 -FLAIR images and diffusion tensor imaging (DTI) were acquired 1 week before radiotherapy. Hyper-signal regions on T 2, T 2 -FLAIR and DTI p-map were segmented by means of semi-automated segmentation. Manual segmentation was used as ground truth. Dice Scores (DS) were calculated for validation of semiautomatic...
Spatiotemporal registration and fusion of transthoracic echocardiography and volumetric coronary artery tree, Article International Journal of Computer Assisted Radiology and Surgery ; Volume 16, Issue 9 , 2021 , Pages 1493-1505 ; 18616410 (ISSN) ; Behnam, H ; Fatemizadeh, E ; Faghihi Langroudi, T ; Bayat, F ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH 2021
Purpose: Cardiac multimodal image fusion can offer an image with various types of information in a single image. Many coronary stenosis, which are anatomically clear, are not functionally significant. The treatment of such kind of stenosis can cause irreversible effects on the patient. Thus, choosing the best treatment planning depend on anatomical and functional information is very beneficial. Methods: An algorithm for the fusion of coronary computed tomography angiography (CCTA) as an anatomical and transthoracic echocardiography (TTE) as a functional modality is presented. CCTA and TTE are temporally registered using manifold learning. A pattern search optimization algorithm, using...
The effect of energy spectrum change on DNA damage in and out of field in 10-MV clinical photon beams, Article Medical and Biological Engineering and Computing ; Volume 53, Issue 1 , January , 2015 , Pages 67-75 ; 01400118 (ISSN) ; Xiao, Y ; Sohrabpour, M ; Studenski, M. T ; Sharif University of Technology
Springer Verlag 2015
The aim of this study was to quantify the DNA damage induced in a clinical megavoltage photon beam at various depths in and out of the field. MCNPX was used to simulate 10 × 10 and 20 × 20 cm2 10-MV photon beams from a clinical linear accelerator. Photon and electron spectra were collected in a water phantom at depths of 2.5, 12.5 and 22.5 cm on the central axis and at off-axis points out to 10 cm. These spectra were used as an input to a validated microdosimetric Monte Carlo code, MCDS, to calculate the RBE of induced DSB in DNA at points in and out of the primary radiation field at three depths. There was an observable difference in the energy spectra for photons and electrons for points...
A new deep convolutional neural network design with efficient learning capability: Application to CT image synthesis from MRI, Article Medical Physics ; Volume 47, Issue 10 , 2020 , Pages 5158-5171 ; Karimian, A ; Fatemizadeh, E ; Arabi, H ; Zaidi, H ; Sharif University of Technology
John Wiley and Sons Ltd 2020
Purpose: Despite the proven utility of multiparametric magnetic resonance imaging (MRI) in radiation therapy, MRI-guided radiation treatment planning is limited by the fact that MRI does not directly provide the electron density map required for absorbed dose calculation. In this work, a new deep convolutional neural network model with efficient learning capability, suitable for applications where the number of training subjects is limited, is proposed to generate accurate synthetic computed tomography (sCT) images from MRI. Methods: This efficient convolutional neural network (eCNN) is built upon a combination of the SegNet architecture (a 13-layer encoder-decoder structure similar to the...