Measurement of the photon and thermal neutron doses of contralateral breast surface in breast cancer radiotherapy

Introduction and purpose:During the radiation therapy of tumoral breast, the contralateral breast (CB) will receive scattered doses. In the present study, the photon and thermal neutron dose values received by CB surface during breast cancer radiation therapy were measured.Materials and methods:The right breast region of RANDO phantom was considered as CB, and the measurements of photon and thermal neutron dose values were carried out on this region surface. The phantom was irradiated with 18 MV photon beams, and the dose values were measured with thermoluminescent dosimeter (TLD-600 and TLD-700) chips for 11 � 13, 11 � 17 and 11 � 21 cm2 field sizes in the presence of physical and dynamic wedges.Results:The total dose values (photon + thermal neutron) received by the CB surface in the presence of physical wedge were 12·06, 15·75 and 33·40 of the prescribed dose, respectively, for 11 � 13, 11 � 17 and 11 � 21 cm2 field sizes. The corresponding dose values for dynamic wedge were 9·18, 12·92 and 29·26 of the prescribed dose, respectively. Moreover, the results showed that treatment field size and wedge type affect the received photon and thermal neutron doses at CB surface.Conclusion:According to our results, the total dose values received at CB surface during breast cancer radiotherapy with high-energy photon beams are remarkable. In addition, the dose values received at CB surface when using a physical wedge were greater than when using a dynamic wedge, especially for medial tangential fields. © Cambridge University Press 2019

The use of EBT3 film and Delta4 for the dosimetric verification of EclipseTM treatment planning system in a heterogeneous chest phantom: An IMRT technique

Background: This study aimed to evaluate the dose calculation accuracy of EclipseTM treatment planning system (TPS) in a heterogeneous chest phantom with the intensity modulated radiotherapy (IMRT) technique using EBT3 film and Delta4. Materials and Methods: Two IMRT plans (A and B) were prepared for radiotherapy of the heterogeneous chest phantom. Plan A was between the left lung and the surrounding soft tissue and plan B was carried out on the soft tissue. EBT3 film and Delta4 were used for dose measurement in the phantom. EclipseTM TPS was also used for dose calculation. Finally, the gamma index values of the TPS with film and TPS with Delta4 were obtained. A 95 passing rate of gamma index with the passing criterion of 3mm/3 and a dose threshold of 20 as the standard criterion was considered in this study. Furthermore, the passing rates of gamma indices of the film and Delta4 were compared with each other via Bland-Altman analysis. Results: The mean passing rate of gamma index with standard passing criterion between the TPS calculations and film measurements was 96.95±0.22, while it was equal to 97.7±0.56 and 98.45±0.21 between the TPS calculations and 2D and 3D Delta4 measurements, respectively. Additionally, the differences between the passing rates of gamma indices of the film and Delta4 were less than 5. Conclusion: The findings demonstrate that the accuracy of dose calculations of EclipseTM TPS in a heterogeneous chest phantom with the IMRT technique is within the standard passing criterion. Furthermore, it can be concluded that there is a good agreement between the film and Delta4, as IMRT QA devices. © 2019 Novin Medical Radiation Institute. All rights reserved

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. © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group

The measurement of thyroid absorbed dose by gafchromic™ EBT2 film and changes in thyroid hormone levels following radiotherapy in patients with breast cancer

Background: Radiotherapy is a main method for the treatment of breast cancer. This study aimed to measure the absorbed dose of thyroid gland using Gafchromic EBT2 film during breast cancer radiotherapy. In addition, the relationship between the absorbed dose and thyroid hormone levels was evaluated. Methods: Forty-six breast cancer patients, with the age ranged between 25 and 35 years, undergoing external radiotherapy were studied. The patients were treated with 6 and 18 MV X-ray beams, and the absorbed thyroid dose was measured by EBT2 film. Thyroid hormone levels, thyroid-stimulating hormone (TSH), triiodothyronine (T3), and thyroxin (T4), were measured before and after the radiotherapy. Pearson's, Spearman's, and Chi-square tests were performed to evaluate the correlation between the thyroid dose and hormone levels. Results: The mean thyroid dose was 26 ± 9.45 cGy with the range of 7.85-48.35 cGy. There were not any significant differences at thyroid hormone levels between preradiotherapy and postradiotherapy (P > 0.05). There was a significant relationship between increased thyroid absorbed dose and changes in TSH and T4 levels (P < 0.05), but it was not significant in T3 level (P = 0.1). Conclusion: Regarding the results, the thyroid absorbed dose can have an effect on its function. Therefore, the thyroid gland should be considered as an organ at risk in breast cancer radiotherapy. © 2020 Isfahan University of Medical Sciences(IUMS). All rights reserved

The measurement of thyroid absorbed dose by gafchromic� EBT2 film and changes in thyroid hormone levels following radiotherapy in patients with breast cancer

Background: Radiotherapy is a main method for the treatment of breast cancer. This study aimed to measure the absorbed dose of thyroid gland using Gafchromic EBT2 film during breast cancer radiotherapy. In addition, the relationship between the absorbed dose and thyroid hormone levels was evaluated. Methods: Forty-six breast cancer patients, with the age ranged between 25 and 35 years, undergoing external radiotherapy were studied. The patients were treated with 6 and 18 MV X-ray beams, and the absorbed thyroid dose was measured by EBT2 film. Thyroid hormone levels, thyroid-stimulating hormone (TSH), triiodothyronine (T3), and thyroxin (T4), were measured before and after the radiotherapy. Pearson's, Spearman's, and Chi-square tests were performed to evaluate the correlation between the thyroid dose and hormone levels. Results: The mean thyroid dose was 26 ± 9.45 cGy with the range of 7.85-48.35 cGy. There were not any significant differences at thyroid hormone levels between preradiotherapy and postradiotherapy (P > 0.05). There was a significant relationship between increased thyroid absorbed dose and changes in TSH and T4 levels (P < 0.05), but it was not significant in T3 level (P = 0.1). Conclusion: Regarding the results, the thyroid absorbed dose can have an effect on its function. Therefore, the thyroid gland should be considered as an organ at risk in breast cancer radiotherapy. © 2020 Isfahan University of Medical Sciences(IUMS). All rights reserved

Trade-off between breast mean glandular dose and image quality in digital and conventional mammogram systems: A multicenter study

Evaluating the patient dose or exposure parameters considering the image quality can improve the chances of accurate diagnosis and reduce the unnecessary exposures from medical devices such as mammography. This study aimed to evaluate digital and conventional mammography machines while considering the trade-off between image quality and mean glandular dose (MGD) using a phantom. In the present study, one full-field digital mammography (FFDM) and two film-screen mammography (FSM) machines were investigated. The MGD values and image quality were assessed using the American College of Radiology (ACR) phantom at various mAs and constant kVp values. The results were obtained and compared with European guidelines. Friedman and Wilcoxon statistical tests were used to show the comparison. The results from the quality control (QC) tests demonstrated that all machines are functioning well. The best image quality in the digital mammography machine was observed at the MGD of 1.8 mGy and 55 mAs. In addition, the two conventional machines had the best image quality regarding the imaging of the ACR phantom at 65 mAs with an MGD of 2.1 mGy. These values were considered as appropriate values for the studied mammography systems. Furthermore, the Friedman test demonstrated that there are significant differences between the measured image quality values obtained from the different machines (p < 0.05), however, according to the Wilcoxon test there were not any significant differences between the conventional machines at various mAs values. Owing to the results, for a medium breast size, the image quality will not be improved with increasing the exposure after a specified MGD corresponds to a certain mAs. It is notable that this value is smaller in digital mammography system at a reasonably low dose