Iranian Journal of Medical Physics
Volume:17 Issue: 4, Jul-Aug 2020

Natural radioactivity in the soil is considered a major indicator of radiological contamination. Primordial radionuclides are the main source of natural radioactivity. Natural radioactivity transfers radionuclides into the environment and poses radiation hazards to people's health. Therefore, the present study aimed to determine the radon concentration and surface exhalation rate in soil samples collected from different locations of industrial, agricultural, and residential of Al-Diwaniyah governorate, southern Iraq.

In the present study, five different depths of 0, 10, 20, 30, and 40 cm were taken from each location. The radon concentration and exhalation rate were measured using CR-39 detectors (Pershore Moulding Ltd, UK). The CR-39 detectors were left inside plastic cans with soil samples. The tracks of nuclear particles were recorded using an optical microscope.

Results of the present study showed that the radon concentrations in soil samples ranged from 163.58 to 689.89 Bq/m3 with a mean value of 350.64 Bq/m3, while surface exhalation rate was found to be ranged from 0.015 Bq/m2.h to 0.063 Bq/m2.h with an average value of 0.031 Bq/m2.h. The obtained results demonstrated that the radon concentration and exhalation rate decreased with increased depth of soil.

Based on the current findings, it was found that radon concentrations in all the examined soil samples were within the acceptable value of 600 Bq/m3, according to the International Commission on Radiological Protection and International Atomic Energy Agency. However, the sample S13 from AL-Hamad village with a mean value of 642.51±22.95 Bq/m3 was an exception.

The current study aimed to compare the performance of radiobiological models in predicting acute esophagitis (AE) complications after three-dimensional conformal radiation therapy (3D-CRT).

Out of a total of 100 patients, 50 patients with concurrent chemotherapy and 50 patients without such therapy were treated with different total doses and a daily dose range of 1.8-2.4 Gy on the basis of 5 days a week for 3 months. Predictions of AE were based on Lyman–Kutcher–Burman (LKB) and equivalent uniform dose (EUD)-based radiobiological models. Consequently, 3 months of follow-upwere performed to monitor the complication incidence among the studied patients. Receiver operating characteristic (ROC) and univariable logistic regression analyses were carried out to determine the effect of mean dose, volume percentage, and weight loss percentage on the probability of AE grade ³ 2.

The EUD-basedmodel showed a better concordance with the clinical data for all patients (area under the curve [AUC]=0.919) and the concurrent chemoradiotherapy (CCRT) group (AUC=0.986). For the radiation therapy group, the LKB model had a better performance than the EUD-based model (AUC=0.921). Grade ³ 2 esophagitis occurred 37.94±4.0 and 68.39±7.1 days after the initiation of radiation therapy in the chemoradiation and radiation therapy groups, respectively.

The EUD-basedmodel showed a higher agreement with the follow-up data. The incidence time of grade ³ 2 AE in the CCRT was approximately two times shorter than that in the non-CCRT group.

In recent years, the number of complex coronary angiography (CA) is increasing rapidly. These procedures have a significant contribution to medical exposure to the general population. Exposure of patients to high doses of x-rays could cause deterministic effects on the skin. Therefore, the assessment of radiation doses of patients is of great importance. This study aimed to assess maximum entrance skin dose (MESD) of patients who underwent interventional cardiology procedures. Moreover, it was attempted to determine the correlation between MESD and other relevant dosimetric parameters.

The MESDs of 32 patients who underwent CA procedures were measured by an array of thermoluminescence dosimeters (TLDs). In this study, a Perspex tray consisting of 5 rows and 6 columns was used to hold the TLDs. Its long axis was perpendicular to the long axis of the table, and the top edges of the tray were approximately equal to the patient’s shoulders.

The results revealed a linear relationship between dose area product (DAP) values and MESDs (R2=0.89; P=0.00). In addition, there was a significant association between MESD and fluoroscopy time (R2=0.89). Moreover, a weak correlation was observed between MESD and the number of frames per second (R2=0.23).

According to the results, the recorded DAP values and fluoroscopy time can be used to estimate the MESDs of patients undergoing coronary fluoroscopy procedures.

Exposure to ionizing radiation can trigger adverse biological effects on healthy tissues, such as causing hematological toxicity and potential injury to different organs. Ionizing radiation has sufficient energy to liberate electrons from atoms leaving them with unpaired electrons; hence ionizing them and producing free radicals. In the current study, the risk of exposing to 6 Gy x-irradiation on alteration of some hematological parameters and liver tissue lipid peroxidation activity in albino mice in the presence and absence of black grape and ginger extracts as antioxidants have been investigated. Albino mice were exposed to 6 Gy wholebody xirradiation in the absence and presence of black grape and ginger extracts (10mL/Kg). The results of the present study showed a significant decrease in mice red blood cell count, hemoglobin, hematocrit, mean corpuscular volume, and mean corpuscular hemoglobin, following the exposure to 6 Gy x-irradiation (P≤0.05), while all the mentioned parameters were relatively shifted toward the normal values in the mice that received black grape and ginger extracts as a treatment prior to the radiation. Accordingly, our results demonstrated a noticeable increase in the malondialdehyde analysis (MDA) level in the 6 Gy group, while a slight depletion in the MDA level was observed in the group of mice that received black grape and ginger extracts, compared to that of the control group.  the administration of black grape and ginger extracts prior to irradiation may protect the mice from excess hepatocyte lipid peroxidation and alteration of hematological parameters.

The present study aimed to measure the scatter and leakage dose received by out-of-field organs while delivering Radiotherapy (RT) treatment of cervical cancer. Moreover, this study estimated the risk of second cancer (SC). The doses to out-of-field organs were measured using a lithium fluoride (TLD 100) dosimeter while delivering External Beam Radiotherapy (EBRT) by 6 MV photon beam with Brachytherapy Boost (BB) treatment in the humanoid phantom.

The excess absolute risk of SC for the stomach, colon, liver, lung, breast, and kidney, as well as excess relative risk for the thyroid, were estimated based on Biological Effects of Ionizing Radiation VII report.

The out-of-field organ doses varied with respect to distance between organs. The colon (3DCRT-282.13 cGy and IMRT-381.24 cGy in 25 fractions) and kidney (70.65 cGy in 3 fractions) received the highest doses with EBRT and BB, respectively. For most of the aforementioned organs, the calculated dose was 0.2 Gy/fraction according to the treatment planning system. With the age at exposure (i.e., 30 years) as a reference, the highest LARs were associated with the colon (0.74%) and breast (2.76%) in 3DCRT plus BB and IMRT plus BB, respectively. The lifetime attributable risk of SC was also shown to decrease with increasing the age at exposure for all the organs.

Although all the evaluated out-of-field organs in this study showed some levels of risk, the risk was more frequently reported for the colon, stomach, and breast with IMRT technique than that in 3DCRT.

According to the American Society of Radiation Oncology, all patients receive radiation therapy during their illness, where radiation is delivered by the medical linear accelerator (Linac). The aim of this study was to evaluate the quality assurance (QA) of the Linac in analyzing the used dose profile in the treatment of cancer tumors.
This experimental study was performed using Linac (synergy device type) at Baghdad Radiotherapy and Nuclear Medicine laboratories, Baghdad, Iraq. The Star Track device was used for the routine quality assurance of the Linac, using photon beam for the reference Dmax and source to surface distance of 100 cm. The Star Track consists of 453 vented parallel plate ionization chambers.
The flatness and symmetry of beams for the reference field size did not exceed from ±2%, as they were within the allowed range. Moreover, the penumbra region showed a change in value that did not exceed from ±0.2 cm. using the Star Track method; maximum differences in beam symmetry and beam flatness were measured at 0.76%±2% and 1.17%±2%, respectively. Moreover, the maximum difference in the penumbra region was estimated at 0.12±0.2 cm.
The results indicated, the Star Track could successfully calculate the characteristics of dose profile during a time period of 2,500 ms, showing the superiority of this instrument over other verification devices.

The present study was conducted to obtain State diagnostic reference levels (DRLs) of five routine computed tomography (CT) examinations from two CT centers in Ondo State and to identify factors responsible for dose variation and escalation in these CT centers.
Acquisition parameters and CT dose indices were collected from the storage drives of the two CT centers namely Federal Medical Centre, Owo and Trauma Center, Ondo, Ondo State, Nigeria, for six months on electronic spreadsheets for cranial, sinus, chest, abdomen and pelvis examinations. In addition, dose indices for multiphase examinations were collected to analyze chest and abdominal doses. Wilcoxon rank-sum test was used to assess variations in dose distributions of the two health institutions.
The following diagnostic reference levels (DRLs) were obtained at 91 mGy; 1943 mGy.cm, 69 mGy; 1159 mGy.cm, 45 mGy; 1064 mGy.cm, 50 mGy; 2545 mGy.cm and 26 mGy; 622 mGy.cm in cranial, sinus, chest, abdomen and pelvis examinations respectively.
Estimated State DRLs exceed national and other DRLs indicating that there is a need to improve the quality of CT-examination for a better benefit to risk ratio.However, benchmarking DRLs to median dose levels (Achievable dose levels) instead of the upper quartile will be a good starting point in achieving the optimal dose level.

Best radiography practice involves operational optimal machine performance, delivering cost-effective healthcare services under appropriate safety conditions for workers and the public. The present study aimed to investigate the safety status of diagnostic X-ray installations in Mizoram, India. Linearity of time (sec), linearity of current (mA), output reproducibility, table dose (μGy/mAs), peak voltage (kVp) accuracy, and 16 essential safety parameters of 135 X-ray machines were considered in this study. A battery-operated dosimeter and wide-range digital kVp meter were used to measure output radiation and effective peak potential of X-ray tube. Data analysis was performed using SPSS software to obtain the mean, standard deviation, and coefficient of variation. Among different electronic parameters, 59.2% linearity of time, 82.6% linearity of current, 89.7% kVp accuracy, 35.1% output reproducibility, and 92.8% table dose were beyond the acceptable limits. Based on 16 essential safety parameters, it was observed that 98.7% of X-ray machines did not receive proper quality assurance test, 1.9% of the installations employed lead-line patient entrance doors, 46.8% of the machines were operated without any protective barriers and 83.1% of the units were operated without personnel monitoring service. The present study had concluded with more problems than the previous studies in different parts of the world in this regard. Due to the absence of proper quality control (QC) programs, many installations did not follow standard installation guidelines. The authors recommended that proper QC should be implemented by the frequent monitoring of each and every diagnostic X-ray installation.