Impact of Dose Calculation Algorithms and Radiobiological Parameters on Prediction of Cardiopulmonary Complications in Left Breast Radiation Therapy.

Background: Breast cancer requires evaluating treatment plans using dosimetric and biological parameters. Considering radiation dose distribution and tissue response, healthcare professionals can optimize treatment plans for better outcomes. Objective: This study aimed to evaluate the effects of the different Dose Calculation Algorithms (DCAs) and Biologically Model-Related Parameters (BMRPs) on the prediction of cardiopulmonary complications due to left breast radiotherapy. Material and Methods: In this practical study, the treatment plans of 21 female patients were simulated in the Monaco Treatment Planning System (TPS) with a prescribed dose of 50 Gy in 25 fractions. Dose distribution was extracted using the three DCAs [Pencil Beam (PB), Collapsed Cone (CC), and Monte Carlo (MC)]. Cardiopulmonary complications were predicted by Normal Tissue Complication Probability (NTCP) calculations using different dosimetric and biological parameters. The Lyman-Kutcher-Burman (LKB) and Relative-Seriality (RS) models were used to calculate NTCP. The endpoint for NTCP calculation was pneumonitis, pericarditis, and late cardiac mortality. The ANOVA test was used for statistical analysis. Results: In calculating Tumor Control Probability (TCP), a statistically significant difference was observed between the results of DCAs in the Poisson model. The PB algorithm estimated NTCP as less than others for all Pneumonia BMRPs. Conclusion: The impact of DCAs and BMRPs differs in the estimation of TCP and NTCP. DCAs have a stronger influence on TCP calculation, providing more effective results. On the other hand, BMRPs are more effective in estimating NTCP. Consequently, parameters for radiobiological indices should be cautiously used s to ensure the appropriate consideration of both DCAs and BMRPs.

Evaluation of organ dose using size-specific dose estimation (SSDE) and related cancer risk due to chest CT scan during the COVID-19 pandemic.

This study aimed to estimate lung and breast doses for individual patients using the size-specific dose estimate (SSDE) method, as well as calculating effective doses, in patients who underwent chest CT scans during the COVID-19 pandemic. Cancer risk incidence was estimated using excess relative risk (ERR), excess absolute risk (EAR), and lifetime attributable risk (LAR) models from the Biological Effects of Ionizing Radiation Report VII (BEIR-VII). Data from about 570 patients who underwent CT scans for COVID-19 screening were utilized for this study. Using the header of the CT images in a Python script, SSDE and effective dose were calculated for each patient. The SSDE obtained by water equivalent effective diameter (wSSDE) was considered as lung and breast dose, and applied in organ-specific cancer risk estimation. The mean wSSDE value for females (13.3 mGy) was slightly higher than that for males (13.1 mGy), but the difference was not statistically significant (P value = 0.41). No significant differences were observed between males and females in terms of calculated EAR and ERR for lung cancer at 5 and 30 years after exposure (P value = 0.47, 0.46, respectively). Similarly, there was no significant difference in lung cancer LAR values between females and males (P value = 0.48). The results also indicated a decrease in LAR values for both lung and breast cancers with increasing exposure age. In accordance with the ALARA (as low as reasonably achievable) principle, it is important for medical staff and the general public to consider the benefits of CT imaging in detecting such infections. Additionally, imaging medical physicists and CT scan experts should optimize imaging protocols and strike a balance between image quality for detecting abnormalities and radiation dose, all while adhering to the ALARA principle.

Comparison of the Effects of Govarcin Herbal Capsule and Metoclopramide for Alleviating Gastrointestinal Symptoms in Patients with Functional Dyspepsia: A Randomized Double-blind Clinical Trial.

BACKGROUND: Functional dyspepsia (FD) is felt as a discomfort or pain on the center line or upper abdomen. In this study, we investigated the effect of Govarcin herbal capsule on FD so that if it is effective, it can be used in the treatment of patients with this disease. METHODS: Totally, 106 patients enrolled in a double-blind, clinical trial study. The participants had FD and were divided into two groups receiving Govarcin and Metoclopramide by block randomization. The patients were treated for four weeks, taking one Govarcin capsule or Metoclopramide tablet after each meal. The rate of improvement in patients was assessed by mitigation of clinical symptoms, including epigastric pain, fullness, discomfort, nausea, vomiting and heartburn. Also, before and after intervention, we used Nepin questionnaire and ROME III. SPSS statistics 25 software was used for data analyzing. RESULTS: Clinical symptom score changes between Govarcin and Metoclopramide patients' groups showed that there was no significant difference in any of the clinical symptom scores (except for heartburn, p-vale=0.012) between the study groups. Nepean score in Govarcin group before and after treatment was 19.3±4.8 and 8.9±2.8, respectively (p-value<0.001). For Metoclopramide group, these values were 19.8±3.5 and 9.4±2.1 respectively (p-value<0.001). No significant difference was found in terms of Nepean score between the Govarcin and Metoclopramide groups (p-value=0.995). CONCLUSION: Govarcin herbal capsule can be used to remedy symptoms in patients with FD. It seems that Guarcin is as effective as metoclopramide in fighting symptoms of FD as no significant difference in efficacy has been demonstrated between them.

Collapsed Cone Superposition Algorithm Validation for Chest Wall Tangential Fields using Virtual Wedge Filters.

Background: Virtual wedge (VW) is used in radiotherapy to compensate for missing tissues and create a uniform dose distribution in tissues. According to TECDOC-1583 and technical reports series no. 430, evaluating the dose calculation accuracy is essential for the quality assurance of treatment planning systems (TPSs). In this study, the dose calculation accuracy of the collapsed cone superposition (CCS) algorithm in the postmastectomy radiotherapy of the chest wall for breast cancer was evaluated by comparing the calculated and measured dose in VW fields. Methods: Two tangential fields with the typical VW angles were planned using ISOgray TPS in a thorax phantom. The CCS algorithm was used for dose calculation at 6 and 15 MV photon beams. The obtained dose distributions from EBT3 film spaces and TPS were evaluated using the gamma index. Results: The measured and calculated dose values using VW in a heterogeneous medium with different beam energies were in a good agreement with each other (acceptance rate: 88.0%-93.4%). The calculated and measured data did not differ significantly with an increase/decrease in wedge angle. In addition, the results demonstrated that ISOgray overestimated and underestimated the dose of the soft tissue and lung in the planned volume, respectively. Conclusions: According to the results of gamma index analysis, the calculated dose distribution using VW model with the CCS algorithm in a heterogeneous environment was within acceptable limits.

The Alleviating Effect of Herniarin Against Ionizing Radiation-Induced Genotoxicity and Cytotoxicity in Human Peripheral Blood Lymphocytes.

BACKGROUND AND OBJECTIVE: Herniarin is a simple coumarin that is found naturally in some plant species. In this study, we aimed to evaluate the protective effect of herniarin against ionizing radiation-induced genotoxicity and cytotoxicity in human peripheral blood lymphocytes. METHODS: Herniarin was added to human lymphocytes before irradiation with a dose of 2 Gy of Xrays. The antagonistic potential of herniarin against radiation was measured by MTT [3-(4,5- dimethyl-2-thiazolyl)-2,5-diphenyl-2H tetrazolium bromide] assay, micronucleus assay, flow cytometry, and reactive oxygen species (ROS) level analysis. RESULTS: The maximum survival of lymphocytes against radiation was observed at a concentration of 50 µM of herniarin and a treatment time of 1 h. Pretreatment with 50 µM herniarin significantly decreased the micronuclei frequency, the percentage of apoptotic lymphocytes, and the ROS level in irradiated human lymphocytes. Moreover, 50 µM herniarin significantly increased the cytokinesis blocked proliferation index in irradiated lymphocytes. CONCLUSION: Herniarin could reduce radiation-induced cytotoxicity and genotoxicity in human lymphocytes. To complete the results of this study, it is suggested that in the future, more preclinical studies with larger samples or animal models be performed on herniarin.

Synthesis of New Thioureas Derivatives and Evaluation of Their Efficacy as Proliferation Inhibitors in MCF-7 Breast Cancer Cells by Using 99mTc-MIBI Radiotracer.

BACKGROUND AND OBJECTIVES: Anti-tumor activity of some thioureas derivatives is well documented in literature and received considerable attention. The present study aims to synthesize and characterize some novel thioureas and carbonylthioureas as anti-tumor agents for MCF-7 breast cancer cells in vitro and in vivo. MATERIALS AND METHODS: Several 1-allyl-3-(substituted phenyl), N,N'-(phenylene) bis(3- allyldithithiourea) and 1-cyclopropanecarbonyl-3-(substituted phenyl)-thioureas derivatives were synthesized and confirmed by FT-IR spectroscopy, NMR and 13C-NMR. Anti-tumor activity of these compounds was determined by various in vitro and in vivo assays including; MTT, tumor volume measurement as well as,99mTc-MIBI tumor uptake in MCF-7 tumor bearing nude mice. RESULTS: Among all of the synthesized compounds, some thioureas derivatives [3i] and [4b] at 100 nM concentration exhibited significant inhibitory effects on the proliferation of MCF-7 cell in vitro. However, this inhibition was not observed in HUVEC human endothelial normal cells. In vivo anti-tumor effects of the synthesized compounds on MCF-7 xenograft mouse models demonstrated a reduction in the tumor volume for various concentrations between 2 to 10 mg/kg after 21 days. These effects were comparable with Tamoxifen as standard anti-estrogen drug. According to the 99mTc-MIBI biodistribution result, treatment of MCF-7 bearing nude mice with both [3i] and [4b] compounds at the maximum concentration (10 mg/kg) can lead to a significant decrease of 99mTc- MIBI tumor uptake. CONCLUSION: Compounds [3i] and [4b] suppressed the growth of MCF-7 cells in the xenograft nude mice at the doses that were well-tolerated. Our study suggests that these new compounds with their significant anti-tumor effects, may serve as useful candidates for breast cancer therapy.

Dosimetric characteristics of LinaTech DMLC H multi leaf collimator: Monte Carlo simulation and experimental study.

This study evaluated the basic dosimetric characteristics of a Dynamic Multi Leaf Collimator (DMLC) using a diode detector and film measurements for Intensity Modulated Radiation Therapy Quality Assurance (IMRT QA). The EGSnrc Monte Carlo (MC) simulation system was used for the determination of MLC characteristics. Radiation transmission and abutting leaf leakage relevant to the LinaTech DMLC H were measured using an EDGE detector and EBT3 film. In this study, the BEAMnrc simulation code was used for modeling. The head of Siemens PRIMUS linac (6 MV) with external DMLC H was entered into a BEAMnrc Monte Carlo model using practical dosimetry data. Leaf material density, as well as interleaf and abutting air gaps were determined according to the computed and measured dose profiles. The IMRT QA field was used to evaluate the dose distribution of the simulated DMLC H. According to measurements taken with the EDGE detector and film, the total average measured leakage was 1.60 ± 0.03% and 1.57 ± 0.05%, respectively. For these measurements, abutting leaf transmission was 54.35 ± 1.85% and 53.08 ± 2.05%, respectively. To adapt the simulated leaf dose profiles with measurements, leaf material density, interleaf and abutting air gaps were adjusted to 18 g/cm3 , 0.008 cm and 0.108 cm, respectively. Thus, the total average leakage was estimated to be about 1.59 ± 0.02%. The step-and-shoot IMRT was implemented and 94% agreement was achieved between the film and MC, using 3%-3 mm gamma criteria. The results of this study showed that the dosimetric characteristics of DMLC H satisfied international standards.

Validation of a Prototype Optical Computed Tomography System.

In radiation cancer treatments, the most of the side effects could be minimized using a proper dosimeter. Gel dosimeter is the only three-dimensional dosimeter and magnetic resonance imaging (MRI) is the gold standard method for gel dosimeter readout. Because of hard accessibility and high cost of sample reading by MRI systems, some other alternative methods were developed. The optical computed tomography (OCT) method could be considered as the most promising alternative method that has been studied widely. In the current study, gel dosimeter scanning using a prototype optical scanner and validation of this optical scanner was performed. Optical absorbance of the irradiated gel samples was determined by both of conventional spectrophotometer and the fabricated OCT system at 632 nm. Furthermore, these irradiated vials were scanned by a 1.5 T MRI. The slope of the curves was extracted as the dose-response sensitivity. The R2-dose sensitivity measured by MRI method was 0.1904 and 0.113 for NIPAM and PAGAT gels, respectively. The optical dose sensitivity obtained by conventional spectrophotometer and the fabricated optical scanner was 0.0453 and 0.0442 for NIPAM gels and 0.0244 and 0.0242 for PAGAT gels, respectively. The scanning results of the absorbed dose values showed that the new OCT and conventional spectrophotometer were in fair agreement. From the results, it could be concluded that the fabricated system is able to quantize the absorbed dose values in polymer gel samples with acceptable accuracy.