in present pet/ct scanners, pet attenuation correction is performed by relying on the information given by ct scan. in the ct-based attenuation correction methods, dual-energy technique (dect) is the most accurate approach, which has been limited due to the increasing patient dose. in this feasibility study, we have introduced a new method that can implement dual-energy technique with only a si...

Introduction: Computed tomography (CT) consists of 11% of all imaging methods, but accounts for approximately 67% of radiation exposure due to diagnostic cases. More than one-third of all CT scans are done in the head and neck area. The thyroid gland is irradiated during CT head and neck. According to studies, this gland has the highest levels of radiation-induced cancer, and i...

Introduction: International Commission on Radiological Protection introduced three basic principles of radiation protection, namely justification, optimization, and dose limit. Medical exposure has no dose limits, and generally, diagnostic reference levels are used as a tool for optimization of patient protection. Material and Methods: Dosimetry was performed on 20 CT scanners located in 14 cit...

Background: Computed Tomography (CT) is main contributor of population dose from diagnostic X-ray examinations. Children are more radiosensitive than adults, thus optimization of CT examination in these patients is essential. The purpose of this study was to evaluate dose delivered to pediatric patients’ undergoing CT examination of the common examinations and also establishing local Diag...

Objective: Resistance of metastatic lymph nodes (LNs) to high dose I-131 therapy is associated with high morbidity in patients with differentiated thyroid cancer. We evaluated the role of F-18 FDG PET/CT in the prediction of resistance to high dose I-131 therapy in patients with papillary thyroid cancer. Methods: The subjects were 307 patients who underwent total or near total thyroidectomy fol...

The increased use of computed tomography (CT) and its high radiation dose have led to great concerns about its potential for radiation induced cancer risks. Breast is a radiosensitive tissue based on tissue weighting factors assigned by the International Commission on Radiological Protection (ICRP). Moreover, the dose is maximal on the surface of the patient. Therefore, strategies should be tak...

background: computed tomography (ct) is main contributor of population dose from diagnostic x-ray examinations. children are more radiosensitive than adults, thus optimization of ct examination in these patients is essential. the purpose of this study was to evaluate dose delivered to pediatric patients’ undergoing ct examination of the common examinations and also establishing local diagnostic...

Background: Worldwide the computed tomography (CT) scanning is recognized as a high radiation dose modality. This article aimed to estimate the radiation dose reduction and radiogenic risks for adult patients undertaking abdominal CT examinations. Materials and Methods: A total of 128 patients were studied using 2, 4, 16 and 64 slice CT scanners. The patients were divided into two categories: t...

Introduction: The dose in computed tomography (CT) often approach or exceed the optimum levels, thereby increasing the probability of cancer induction. With wide application of this diagnostic test, it is expedient to determine the effective dose (ED) for each patient to estimate their cancer risk. This study was conducted to investigate the patient-specific dose (PSD) and cancer risk in CT exa...