Radiation Dose
Is the risk of developing cancer from radiation dependent on previous radiation dose? In order to answer the question, “Should previous CT dose influence a given exam?” we need to understand if there are cumulative effects of being exposed to radiation that will change the relative risk for subsequent exams. For each patient that is […]
LET (Linear Energy Transfer), RBE (Relative Biological Effectiveness) and OER (Oxygen Enhancement Ratio) are important terms in radiation biology and relate to the relative damage that will occur with radiation under different circumstances. As LET increases there are more energetic electrons deposited closely together and thus damage to DNA is more likely. Therefore, even with
LET, RBE and OER (Oh My!). Radiologic Technologists Guide to 3 Radiation Biology Terms. Read More »
Radiation damage can be either acute or chronic depending on the conditions. Acute radiation effects are due to short exposures to radiation at a relatively high dose rates and the impact is observed within days or weeks (examples include acute radiation syndromes). Whereas chronic radiation effects are typically associated with lower doses and the effects
Radiation Carcinogenesis In this post we will describe the stochastic effect of radiation carcinogenesis (a fancy way of saying a higher risk of cancer induction after being exposed to ionizing radiation). The mechanism for carcinogenesis is primarily x-rays coming in, generating energetic electrons which then either directly or indirectly cause DNA damage. The data which
Radiation risks to germline cells (sperm and ova) include reduced fertility, and hereditary risks of increased mutation rate. These effects are dependent on the radiation dose: (males) [0.15-0.5 Gy] reduced sperm count, [0.5-6 Gy] temporary sterility, [greater 6 Gy] permanent sterility, and (females) [2-12 Gy depending on age] causes permanent sterility. Hereditary risks of increased
The acute radiation syndromes are cause by a sudden large dose of radiation to the body and depending upon the dose level one will experience either: Cerebral Vascular (a.k.a. CNS) Syndrome, Gastrointestinal (GI) syndrome, or hematopoietic (bone marrow) syndrome. This listed order is the order of severity and of the higher dose levels lead to
Acute Radiation Syndromes [ Hematopoietic, GI, CNS ] for Radiologic Technologists Read More »
Cataracts are formed when cells are damaged or die in the lens of the eye. The dose level which leads to cataract induction depends on the dose fractionization, ie. how many weeks/months was the dose delivered. The radiation dose which has been shown to cause cataract is between 2mGy (single fraction) -5.5 mGy (dose distributed
Cataract Induction from X-ray Radiation (Illustrations, Dose levels) Read More »
The motivation for gonad shielding is to reduce the hereditary specific risks of radiation, and it is still common practice at many institutions. The reasons that shielding will soon be phased out include: hereditary risk in humans has not been demonstrated even at high doses, the radiation doses have reduced greatly from the 1950s (orders
The body is composed of individual cells wherein the genetic information is stored in DNA (deoxyribose nucleic acid). This DNA can be damaged by ionizing radiation, i.e. radiation which has sufficient energy to remove electrons from atoms. The DNA damage can be either direct (i.e. the electron hits the DNA directly) or indirect (i.e. the
The radiation dose for x-ray radiography and CT is compared with the background radiation dose levels (average in United States of 3mSv). The different exams Abdomen, Bone, Head and Neck, Chest, Cardiac, and Mammography are presented. For reference the sources of background radiation of cosmic radiation and Radon are presented. Background Radiation Overview To provide
