علیرضا شیرازی
دانشیار، دکتری تحصصی ،گروه فیزیک پزشکی، دانشکده فیزیک پزشکی، دانشگاه علوم پزشکی، تهران، ایران
[ 1 ] - افزایش حساسیت تومور به اشعه با استفاده از سلکوکسیب
زمینه و هدف: سرطان یکی از مهمترین عوامل مرگ‌ومیر در دنیا میباشد. به دلیل پیشرفتهای قابل توجه در علم زیستشناسی مولکولی و سلولی، روشهای قبلی درمان سرطان با استراتژیهای جدید بهبود یافتهاند. شناسایی و استفاده از حساسکنندههای شیمیدرمانی و پرتودرمانی و تأثیرات آنها بر تخریب بیشتر بافت تومورال روش درمانی جدید میباشد. آنزیم COX-2 نیز با سلکوکسیب مهار و از ترمیم مجدد تومور جلوگیری مینماید. ...
[ 2 ] - بررسی شبیه سازی اثرات هایپرترمیای ناشی از کاربرد نانوذرات مغناطیسی بربافت همگن واقع در میدان مغناطیسی خارجی
چکیدهدر مطالعات کلینیکی , مشخص کردن توزیع دما درون بافت سالم و نیز بافت تومورال در طی درمان هایپرترمیا دشوار است. از آن جایی که باحس گر های مرسوم دما تنها در تعداد محدودی مکان اندازه گیری می شود مطالعات شبیه سازی کمک می کند که پزشکان به درک بهتری از این روش درمانی دست پیدا کنند. در این مطالعه، سه مدل تومور دو بعدی بر اساس تصاویر توزیع های نانو ذره در تومورهای PC3، DU145 وLAPC4 در محیط COM...
[ 3 ] - The Effect of Breast Reconstruction Prosthesis on Photon Dose Distribution in Breast Cancer Radiotherapy
Introduction: Siliconeprosthetic implants are commonlyutilizedfor tissue replacement and breast augmentation after mastectomy. On the other hand, some patients require adjuvant radiotherapy in order to preventlocal-regional recurrence and increment ofthe overall survival. In case of recurrence, the radiation oncologist might have to irradiate the prosthesis.The aim of this study was to evaluate...
[ 4 ] - Experimental Evaluation of Depth Dose by Exit Surface Diode Dosimeters for Off-Axis Wedged Fields in Radiation Therapy
Introduction Evaluation of the delivered dose of externally wedged photon beams by external diode dosimeters during the treatment process requires the estimation of exit surface dose correction factors in various wedge angles and field sizes. Materials and Methods A system of absorbed dose evaluation, using p-type diode dosimeters placed on the exit surface of a phantom, was characterized for e...
[ 5 ] - A Dosimetric Evaluation of Organs at Risk in Prostate Radiation Therapy using a MAGIC Gel Dosimeter
Introduction: Multiple fields and presence of heterogeneities create complex dose distributions that need three dimensional dosimetry. In this work, we investigated MR-based MAGIC gel dosimetry as a three-dimensional dosimetry technique to measure the delivered dose to bladder and rectum in prostate radiation therapy. Materials and Methods: A heterogeneous slab phantom including bones was made....
[ 6 ] - Megavoltage X-ray Dose Enhancement with Gold Nanoparticles in Tumor Bearing Mice
One of the applications of gold nanoparticles (GNPs) in medicine is radiation dose-enhancing effect. Although there are many simulations, in vitro and in vivo evidence that GNPs can enhance significantly the radiation dose effect of orthovoltage beams. These beams compared with megavoltage (MV) beams, have limited applications in radiotherapy. In order to evaluate GNPs radiosensitization perfor...
[ 7 ] - Evaluating the Expression of NOX2 and NOX4 Signaling Pathways in Rats’ Lung Tissues Following Local Chest Irradiation; Modulatory Effect of Melatonin
Lung injury is one of the major concerns for chest cancer patients that undergo radiotherapy as well as persons exposed to an accidental radiological event. Reduction/oxidation (redox) system plays a key role in lung injury via chronic upregulation of pro-oxidant enzymes. NOX2 and NOX4 are two important reactive oxygen species generating enzymes that are involved in radiation toxicity in some o...
[ 8 ] - In vivo dosimetry of intraoral stent using TLD during external photon beam radiotherapy of oral cavity
Introduction: Individual oral stent is a mouth-opening device that used in head and neck cancer radiotherapy with the intention of decreasing radiation dose to health tissues. The aim of this study was to check the dose delivered to both the hard palate and tongue when patient uses the stent during radiotherapy of tongue carcinoma. Methods and materials<stron...
[ 9 ] - The effect of melatonin on Superoxide dismutase and Glutathione peroxidase activity, and Malondialdehyde levels in the targeted and the non-targeted lung and heart tissues after irradiation in xenograft mice colon cancer
Introduction: Introduction: Radiation causes damage to irradiated tissues and also tissues that do not receive direct irradiation through a phenomenon called bystander effects. Melatonin as a potent antioxidant and anti-inflammatory agent is known for protection of normal tissues against ionizing irradiation. In addition, some studies have suggested that Melatonin may have some...
[ 10 ] - Study the effect of source to diaphragm distance (SDD) on beam penumbra width of Gamma Knife machine model 4C using Monte Carlo simulation
Introduction: Stereotactic radiosurgery (SRS) is one of the conformal radiotherapy methods and Gamma Knife is a non-invasive SRS technique to treat intracranial lesions with 201 Co- 60 sources without need to surgery and bleeding. Beam penumbra phenomenon leads to irradiation outside the field and normal tissues. Therefore, considering it is momentous to attain the acceptable t...
[ 11 ] - Protective Effect of Low Dose Melatonin on Radiation-Induced Damage to Rat Liver
Background: Melatonin is a free radical scavenger. It has also antioxidant effects through its stimulatory actions on antioxidant system. Objective: We conducted this study to examine the effect of different oral doses of melatonin on liver tissue. Methods: We used 42 rats—6 rats in each group. Group I served as the control group; group II rats were pretreated with only melatonin; group III w...
[ 12 ] - Radio-Protective Effects of Some bis-Thiosemicarbazone Compounds
Background: GTS, PTSM and ATSM are bis-thiosemicarbazone ligands used in the preparation of copper radiopharmaceuticals. Chemical structure of these materials indicates that they should have radio-protective effects.Objective: To study the radio-protective effects of GTS, PTSM and ATSM. Methods: This study has focused on radio-protective effects of these compounds at different doses (20, 40 and...
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