Assessment of Patient Radiation Dose in Interventional Procedures at Shahid Madani Heart Center in Khorramabad, Iran

Introduction: Coronary angiography is the most common angiographic procedure for diagnosis and treatment of the heart diseases. Herein, we aimed to evaluate the entrance surface dose (ESD), dose area product (DAP), as well as cancer risk in interventional cardiology procedures. Materials and Methods: This study was conducted during July-December 2015 at Shahid Madani Heart Center in Khorramabad, Iran. A total of 225 adult patients including 122 females and 103 males regardless of the risk factors for coronary diseases were participated. Of them, 199 and 26 patients underwent diagnostic coronary angiography (CA) and percutaneous transluminal coronary angioplasty (PTCA), respectively. Each patient underwent CA or PTCA separately. All the procedures were carried out using Siemens angiography system with the pulsed fluoroscopy of 10-30 pulses/s and cine frame rate of 15 frames/s. DAP, ESD, fluoroscopy time (FT), as well as the number of sequences and frames per sequence were collected for each 199 CA and 26 PTCA procedures. Results: The median values of DAP were 19.77±14.88 and 57.11±33.36 Gy.cm2 in CA and PTCA, respectively. In addition, the median values of ESD were 323.12±245.39 and 1145.22±594.42 mGy in CA and PTCA, respectively. FTs were 114.59±74.33 s in CA and 424.15±292.93 s in PTCA. Conclusion: The average patient dose and cancer risk estimates in both CA and PTCA were consistent with the reference levels. However, in agreement with other interventional procedures, dose levels in the interventional cardiology are influenced by staff and clinical protocols, as well as the type of equipment

Numerical Study for Optimizing Parameters of High-Intensity Focused Ultrasound-Induced Thermal Field during Liver Tumor Ablation: HIFU Simulator

Introduction High intensity focused ultrasound (HIFU) is considered a noninvasive and effective technique for tumor ablation. Frequency and acoustic power are the most effective parameters for temperature distribution and the extent of tissue damage. The aim of this study was to optimize the operating transducer parameters such as frequency and input power in order to acquire suitable temperature and thermal dose distribution in the course of a numerical assessment. Materials and Methods To model the sound propagation, the Khokhlov-Zabolotskava-Kuznetsov (KZK) nonlinear wave equation was used and simulation was carried out using MATLAB HIFU toolbox. Bioheat equation was applied to calculate the transient temperature in the liver tissue. Frequency ranges of 2, 3, 4, and 5 MHz and power levels of 50 and 100 W were applied using an extracorporeal transducer. Results Using a frequency of 2 MHz, the maximum temperatures reached 53°C and 90°C in the focal point for power levels of 50 W and 100 W, respectively. With the same powers and using a frequency of 3 MHz, the temperature reached to 71°C and 170°C, respectively. In addition, for these power levels at the frequency of 4 MHz, the temperature reached to 72°C and 145°C, respectively. However, at the 5 MHz frequency, the temperature in the focal spot was either 57°C or 79°C. Conclusion Use of frequency of 2 MHz and power of 100 W led to higher thermal dose distribution, and subsequently, reduction of the treatment duration and complications at the same exposure time in ablation of large tumors

Health Risk Assessment of Natural Background Radiation in Residents of Khorramabad, Iran

Introduction Radioactive materials naturally exist in the world. Indeed, approximately 82% of human-absorbed radiation doses, which are out of human control, arise from natural sources of radiation including cosmic, terrestrial, and exposure through inhalation or ingestion. Thus, the aim of the present study was to estimate health risk, as well as the effective and organ doses from naturally occurring background radiation in residents living in the vicinity of Khorramabad, Iran. Materials and Methods This cross-sectional study was carried out in Khorramabad, Iran. The measurements were performed using Geiger-Muller detector (RDS-110) during daylight from April to June, 2015. The natural gamma radiation measurements were made both indoor and outdoor across five regions of Khorramabad (north, south, west, east, and center). Results The estimated mean absorbed dose rate in outdoor and indoor zones were 0.09±0.024 and 0.117±0.032 mSvy-1, respectively. Additionally, the mean annual effective dose was calculated as 0.69±0.19 mSvy-1, while the estimated health risk probability was 0.0345%. Conclusion The average annual effective dose arising from gamma background radiation was higher than global values. Therefore, more studies are required to examine the relationship between radiation-induced effects and the natural background radiation level in Khorramabad