Orders of magnitude (radiation) Orders of magnitude (radiation) Recognized effects of higher acute radiation doses are described in more detail in the article on radiation poisoning. Although the International System of Units (SI) defines the sievert (Sv) as the unit of radiation dose equivalent, chronic radiation levels and standards are still often given in units of millirems (mrem), where 1 mrem equals 1/1000 of a rem and 1 rem equals 0.01 Sv. Light radiation sickness begins at about 50–100 rad (0.5–1 gray (Gy), 0.5–1 Sv, 50–100 rem, 50,000–100,000 mrem). The following table includes some dosages for comparison purposes, using millisieverts (mSv) (one thousandth of
Biological effects of radiation on the epigenome the normal development of the brain. DNA methylation influences tissue responses to ionizing radiation. Modulation of methylation in the gene MGMT or in transposable elements such as LINE1 could be used to alter tissue responses to ionizing radiation and potentially opening new areas for cancer treatment. MGMT serves as a prognostic marker in glioblastoma. Hypermethylation of MGMT is associated with the regression of tumors. Hypermethylation of MGMT silences its transcription inhibiting alkylating agents in tumor killing cells. Studies have shown patients who received radiotherapy, but no chemotherapy after tumor extraction, had an improved response to radiotherapy due to the methylation