A Study of Sonodynamic Therapy of Melanoma C540 Cells in Vitro by Titania/Gold Nanoparticles.

Background: Sonodynamic Therapy (SDT), a safe and non-invasive strategy in tumor therapy, is in development using novel sono-sensitizers, activated by low-intensity ultrasound radiation. SDT mainly progresses through Reactive Oxygen Species (ROS) generation followed by cell annihilation. Objective: The current study aimed to investigate the effect of ultrasound therapy with titania/gold nanoparticles (NPs) on melanoma cancer. Material and Methods: In this experimental study, Titania/gold NPs (TGNPs) were synthesized, and their activity was investigated in sonodynamic therapy of a melanoma cancer cell line (C540). SDT was performed at 1.0 W cm-2 and 1.0 MHz for one minute. Results: The synthesized NPs that comprised gold NPs of <10 nm into titania NPs of <20 nm showed great stability and cytocompatibility. While TGNPs were biocompatible, a remarkable rate of cell ablation was observed upon ultrasound irradiation due to ROS generation. Conclusion: The SDT using TGNPs can be introduced as an alternative and low-cost treatment method for melanoma malignancy.

Out-of-Field Dose Measurement by TLD Dosimetry and Estimation of Radiation-Induced Secondary Cancer Risk of Thyroid and Breast from Head Radiotherapy.

Background: Radiation therapy, the most common form of cancer treatment, can result in late complications, such as secondary breast and thyroid cancers. Objective: This study aimed to evaluate the risk of secondary cancers using two radiobiological models of Excess Absolute Risk (EAR) and Excess Relative Risk (ERR) in patients with brain cancer undergoing radiotherapy for improved survival rates of cancer patients. Material and Methods: In this expository cross-sectional study, 45 patients under the age of 40 years underwent Whole Brain Radiotherapy (WBRT) using a compact accelerator in Shahid Ramezanzadeh Hospital, Yazd, Iran. Out-of-field organ dose measurement was performed using a Thermoluminescent Dosimeter (TLD) to determine the dose to thyroid and breast tissues. The risk of secondary cancers in these organs was calculated 3, 5, 10, 15, and 20 years after radiation therapy. Results: The mean values of thyroid cancer risk in men and women were 0.418±0.509 and 0.274±0.306, respectively. ERR values of breast cancer in 3-, 5-, 10-, 15-, and 20-year women undergoing radiation therapy were 1.084±2.938, 0.594±1.407, 0.248±0.497, 0.138±0.248, and 0.091±0.148, respectively. EAR values of breast cancer in 3-, 5-, 10-, 15-, and 20-year women following radiation therapy were 0.064±0.060, 0.077±0.071, 0.119±0.100, 0.178±0.248, and 0.259±0.178, respectively. Conclusion: After irradiation, the risk of secondary cancer is affected by factors, such as the patient's age and gender. The secondary thyroid cancer is higher than that of other organs, such as the breast, in the patients undergoing WBRT.

Patterns and trends of population radiation exposure and projected the risk of exposure-induced death from gamma camera examinations in Yazd Province.

INTRODUCTION: The use of nuclear medicine examinations as imaging modalities has recently increased. This study aimed to assess the radiation dose delivered to patients from common diagnostic nuclear medicine examinations and estimate the risk of exposure-induced death (REID). In addition, the frequency of nuclear medicine procedures were evaluated from 2015-2018. MATERIALS AND METHODS: The data were collected from adult patients who had undergone cardiac, skeletal, renal, lacrimal, and thyroid imaging. For each patient, the effective dose was calculated using dose conversion factors, and REID was estimated using PCXMC. The frequency of examinations between 2015 and 2018 was obtained from the hospital information system (HIS). RESULTS: The highest estimated effective dose was attributed to the scans of myocardial stress (8.09 ± 1.28 mSv), myocardial rest (5.59 ± 1.27 mSv), and thyroid imaging (3.93 ± 0.55 mSv). In addition, cardiac stress examination had the highest REID values for solid cancers (212.5 ± 67.5) and bone scans had the highest REID values for leukemia (11.5 ± 2.5). A large increase in the number of myocardial perfusion scans was a significant contributor to an increase in collective effective dose from 23.37 man-Sv in 2015 to 49.47 man-Sv in 2018, a compound annual growth rate (CAGR) of 26%. CONCLUSION: Although the annual frequency and per capita effective dose of nuclear medicine procedures in Yazd Province increased continuously, they were comparably lower than those reported for other countries. Despite this, the cancer risks of nuclear medicine scans at the individual level are negligible (around 0.01% excess fatal cancer risk), yet the increasing tendency for these examinations could be of concern.

ESTIMATION OF DIAGNOSTIC REFERENCE LEVELS AND ACHIEVABLE DOSES FOR PEDIATRIC PATIENTS IN COMMON COMPUTED TOMOGRAPHY EXAMINATIONS: A MULTI-CENTER STUDY.

This study was conducted to determine first local diagnostic reference levels (DRLs) and achievable doses (ADs) for pediatric patients during the most common computed tomography (CT) procedures in Yazd province. The DRL was obtained based on volume CT dose index (CTDIvol) and dose length product (DLP) for four various age groups of children. Data were collected from the most commonly performed pediatric CT scans, including abdomen-pelvis, chest, brain and sinus examinations, at six high-loaded institutes. The patients' data (766 no.) in terms of CTDIvol and DLP were obtained from four age groups: ≤1-, 1-5-, 5-10- and 10-15-y-old. The 75th percentiles of CTDIvol and DLP were considered as DRL values and the 50th percentiles were described as ADs for those parameters. Consequently, the acquired DRLs were compared with other national and international published values. The DRLs in terms of CTDIvol for abdomen-pelvis, chest, brain and sinus examinations were 3, 8, 9 and 10 mGy; 4, 5, 5 and 5 mGy; 25, 28, 29 and 38 mGy; and 23, 24, 26 and 27 mGy for four different age groups of ≤1-, 1-5-, 5-10- and 10-15-y-old, respectively. The DRL values in terms of DLP were 75, 302, 321 and 342 mGy.cm; 109, 112, 135 and 170 mGy.cm, 352, 355, 360 and 481 mGy.cm; and 206, 211, 228 and 245 mGy.cm, respectively, for the mentioned age groups. In this study, the DRL and AD values in the brain examination were greater among the other studied regions. The DRL plays a critical role in the optimization of radiation doses delivered to patients and in improving their protection. This study provides the local DRLs and ADs for the most common pediatric CT scanning in Yazd province to create optimum situation for the clinical practice.

Radiation dose and risk of exposure-induced death associated with common computed tomography procedures in Yazd Province.

PURPOSE: This survey was conducted to evaluate the radiation dose delivered to the patients through different CT procedures along with its corresponding risks in Yazd province. METHOD: Data for the five most common procedures were collected from six institutions from September 2017. The effective dose for each patient was estimated by ImpactDose software. The risk of exposure-induced death (REID) was calculated by coupling the BEIR VII model and ICRP 103 data for the Asian population. RESULTS: The median effective doses for the five most common procedures, in descending order, were as follows: 5.19 mSv for abdomen-pelvis, 3.30 mSv for routine chest, 3.00 mSv for chest HRCT, 0.76 mSv for Brain and 0.47 mSv for sinus. Averaged over all the procedures, the ratio of maximum to minimum of effective dose was 90-fold. The highest associated risk was tied to high-resolution CT scans for women which was estimated to be 1 exposure-induced death related to 2096 scans performed on a 20-year old patient. CONCLUSION: The estimated effective doses for all the procedures except sinus were comparably low, however, the variations among patient doses, even for a given procedure, were substantially high, indicating that further optimization processes need to be undertaken. Moreover, it was estimated that approximately 2000 scans of abdomen-pelvis performed on 20 year-old women could result in 1 radiation-induced cancer death, which in large scales may cause drastic health issues. In this regard, several approaches, one of which is the implementation of DRLs, can be suggested to reduce the collective dose from CT scans.

European trends in radiology: investigating factors affecting the number of examinations and the effective dose.

The advances in technology have led to a growing trend in population exposure to radiation emerging from the invention of high-dose procedures. It is, for example, estimated that annually 1.2% of cancers are induced by radiological scans in Norway. This study aims to investigate and discuss the frequency and dose trends of radiological examinations in Europe. European Commission (EC) launched projects to gain information for medical exposures in 2004 and 2011. In this study, the European Commission Radiation Protection (RP) reports No. 154 and 180 have been reviewed. The RP 154 countries' data were extracted from both reports, and the average variation trend of the number of examinations and effective doses were studied. According to the results, plain radiography and fluoroscopy witnessed a reduction in the frequency and effective dose per examination. Nevertheless, European collective dose encountered an average increase of 23%, which resulted from a growing tendency for implementation of high-dose procedures such as CT scans and interventional examinations. It is worth noting that most of the CT procedures have undergone an increase in effective dose per examination. Although demand and dose per examination in some radiological procedures (such as intravenous urography (IVU) have been reduced, population collective dose is still rising due to the increasing demand for CT scan procedures. Even though the individual risks are not considerable, it can, in a large scale, threaten the health of the people at the present time. Due to this fact, better justification should be addressed so as to reduce population exposure.

Photosensitizer effects of MWCNTs-COOH particles on CT26 fibroblastic cells exposed to laser irradiation.

In the current study, photosensitizer effect of carboxylate multiwalled carbon nanotubes (MWCNTs-COOH) on CT26 fibroblastic cells following near infrared (NIR) irradiation was quantized in photo-thermal therapy (PTT). Moreover, it was tried to achieve optimal dose of MWCNTs-COOH and laser exposure time. Characterizations of MWCNTs-COOH were scrutinized using scanner electron microscope (SEM), spectrophotometer, and particle size analyzer. The seeded CT26 cells were treated with nontoxic concentrations of MWCNTs-COOH and then irradiated. Finally, viability (%) of the CT26 cells was determined using MTT assay. The findings revealed that 10, 50, and 80 µg/mL of MWCNTs-COOH have remarkable photosensitizer effects on CT26 cancerous cell lines against NIR irradiation (2.5 W/cm2). It was shown that using the 80 µg/mL concentration of MWCNTs-COOH against 60, 120, 180, 240, and 300 s of NIR irradiation and also, 10 and 50 µg/mL concentration of MWCNTs-COOH against 180, 240, and 300 s of NIR irradiation can lead to significant decrease in mean cell viability (%) by more than 50%. According to the obtained data, it seems that using the PPT with MWCNTs-COOH, as adjunct therapy in CT26 fibroblastic cells, can help to increase therapeutic ratio of main modalities of cancer treatment such as radiotherapy, chemotherapy, and surgery.

Estimation of radiation dose-reduction factor for cerium oxide nanoparticles in MRC-5 human lung fibroblastic cells and MCF-7 breast-cancer cells.

In the current study, radiation dose-reduction factor (DRF) of nanoceria or cerium oxide nanoparticles (CONPs) in MRC-5 Human Lung Fibroblastic Cells and MCF-7 Breast-Cancer Cells was estimated. Characterization of CONPs was determined using scanner electron microscope (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM) and spectrophotometer. Then, six plans were designed with different radiation dose values on planning target value. The obtained MRC-5 and MCF-7 cells were treated with non-toxic concentrations of CONPs and then exposed. Finally, cell viability (%) of the cell lines was determined using MTT assay. The findings showed that CONPs have no significant radioprotective effect against 10 cGy radiation dose value. Nevertheless, 70 µM CONPs resulted in a significant radioprotection against 100, 200, 300, 400 and 500 cGy radiation dose values compared with the control group in MRC-5 cells. For all radiation dose values, mean cell viability (%) of MCF-7 had not increased significantly at the presence of nanoceria compared with control group. According to the findings, it was revealed that the use of CONPs have a significant radioprotective effect on normal lung cells, while they do not provide any protection for MCF-7 cancer cells. These properties can help to increase therapeutic ratio of radiotherapy.