Radiobiological comparison of 3D conformal and intensity modulated radiation therapy in the treatment of left-sided breast cancer

Background: The current study aimed to compare the tumor control probability (TCP) and normal tssue complicaton probability (NTCP) of three-dimensional conformal radiaton therapy (3D-CRT) and intensity-modulated radiaton therapy (IMRT) for left-sided breast cancer using radiobiological models. Methods: This study was conducted on 30 patents with left-sided breast cancer, who were planned for 3D-CRT and 6-9 fields IMRT treatments using the PROWESS treatment planning system. The planning target volume (PTV) dose of 50 Gy was administered for the 3D-CRT and IMRT plans, respectvely. The Niemierko's equivalent uniform dose (EUD) model was utlized for the estmaton of tumor control probability (TCP) and normal tssue complicaton probability (NTCP). Results: According to the results, the mean TCP values for 3D-CRT, 6-fields IMRT, and 9-fields IMRT plans were 99.07 ±0.07, 99.24 ±0.05 and 99.28 ±0.04, respectvely, showing no statstcally significant difference. The NTCPs of the lung and heart were considerably lower in the IMRT plans, compared to those in the 3D-CRT plans. Conclusions: From the radiobiological point of view, our results indicated that 3D-CRT produces a lower NTCP for ipsilateral lung. In contrast, for TCP calculatons, there was a higher gain with IMRT plans compared to 3D-CRT plans. © 2020 Novin Medical Radiation Institute. All rights reserved

Detection of Ultraweak Photon Emission (UPE) from Cells as a Tool for Pathological Studies

Objective: It is well-known that all living cells emit ultra-weak photon emission (UPE), which is due to byproducts of chemical reactions in cell metabolisms. It has been shown that Reactive Oxygen Species (ROS) in the cells enhances the UPE intensity. The magnitude of such UPE is extremely weak (i.e. a few to 103 photons/ (sec.cm2)), and the detection of such ultra-weak signals is hardly possible via sensitive instruments like photomultiplier tube (PMT) that can detect single photons. Materials and Methods: H2O2 factor with various concentrations was applied on the HT-29 cells to generate ROS. H2O2 concentrations were so low to be nondestructive to the cells. Then, the effect of ROS generation on UPE intensity was investigated. PMT was used to detect UPE from HT-29 cells. Results: The topical application of H2O2 was significantly different (P 0.01) for integrated UPE in the cell groups in the presence of H2O2. Conclusion: The results show that the recorded UPE from HT-29 cells increased with the topical application of exogenous ROS inducer. As a result, UPE can be used as a non-invasive technique for monitoring ROS in cells