The raised use that radioisotopes has led to increased comes to over the effects of these products on biological systems (such together humans). Every radioactive nuclides emit high-energy corpuscle or electromagnetic waves. As soon as this radiation encounters life cells, it can reason heating, rest aufdercouch.netical bonds, or ionize molecules. The many serious organic damage results as soon as these radiation emissions fragment or ionize molecules. Because that example, alpha and beta corpuscle emitted from nuclear decay reactions own much greater energies than ordinary aufdercouch.netical shortcut energies. As soon as these corpuscle strike and penetrate matter, they create ions and also molecular fragments that are incredibly reactive. The damages this does to biomolecules in life organisms can cause serious malfunctions in normal cell processes, count the organism’s fix mechanisms and also possibly causing illness or even fatality (Figure (PageIndex1)).

You are watching: A geiger counter measures radiation indirectly by measuring


Energy took in from nonionizing radiation increases the activity of atoms and also molecules, which is indistinguishable to heater the sample. Although biological systems space sensitive to heat (as we can know from touching a warm stove or spending a day at the coast in the sun), a large amount of nonionizing radiation is necessary prior to dangerous levels room reached. Ionization radiation, however, may reason much more severe damage by breaking bonds or removing electron in biological molecules, disrupting your structure and function. The damages can additionally be done indirectly, by an initial ionizing H2O (the many abundant molecule in life organisms), which forms a H2O+ ion that reacts through water, creating a hydronium ion and a hydroxyl radical:

Figure (PageIndex3).
api/deki/files/56209/CNX_aufdercouch.net_21_06_Penetrate.jpg?revision=1&size=bestfit&width=731&height=312" />Figure (PageIndex4): The capacity of different species of radiation to happen through product is shown. From the very least to many penetrating, they space alpha

For plenty of people, among the largest sources the exposure come radiation is from radon gas (Rn-222). Radon-222 is an α emitter v a half–life the 3.82 days. It is among the commodities of the radiation decay collection of U-238, i m sorry is found in trace amounts in soil and also rocks. The radon gas the is developed slowly escapes native the ground and also gradually seeps into homes and other structures above. Because it is about eight times an ext dense than air, radon gas accumulates in basements and also lower floors, and slowly diffuses throughout structures (Figure (PageIndex5)).

api/deki/files/56211/CNX_aufdercouch.net_21_06_Monitors.jpg?revision=1" />Figure (PageIndex6): tools such as (a) Geiger counters, (b) scintillators, and (c) dosimeters deserve to be provided to measure up radiation. (Credit c: modification of work-related by “osaMu”/Wikimedia commons.)

A variety of devices are provided to measure various aspects of radiation (Table (PageIndex1)). The SI unit for price of radioactive degeneration is the becquerel (Bq), with 1 Bq = 1 disintegration per second. The curie (Ci) and millicurie (mCi) are much bigger units and also are generally used in medicine (1 curie = 1 Ci = (3.7 imes 10^10) disintegrations every second). The SI unit for measuring radiation dose is the gray (Gy), v 1 Gy = 1 J of energy soaked up per kilogram that tissue. In medical applications, the radiation soaked up dose (rad) is an ext often used (1 rad = 0.01 Gy; 1 rad outcomes in the absorption of 0.01 J/kg that tissue). The SI unit measuring tissue damages caused through radiation is the sievert (Sv). This takes into account both the energy and the organic effects that the kind of radiation associated in the radiation dose.

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Table (PageIndex1): Units used for measuring Radiation Measurement PurposeUnitQuantity MeasuredDescription
activity that source becquerel (Bq) radioactive decays or emissions amount the sample that undergoes 1 decay/second
curie (Ci) amount that sample that undergoes (mathrm3.7 imes 10^10; decays/second)
absorbed dose gray (Gy) energy took in per kg of tissue 1 Gy = 1 J/kg tissue
radiation took in dose (rad) 1 rad = 0.01 J/kg tissue
biologically effective dose sievert (Sv) tissue damage Sv = RBE × Gy
roentgen identical for man (rem) Rem = RBE × rad

The roentgen equivalent for man (rem) is the unit for radiation damage that is provided most frequently in medication (1 rem = 1 Sv). Note that the tissue damage units (rem or Sv) includes the energy of the radiation sheep (rad or Gy), together with a biological factor referred to as the RBE (for relative biological effectiveness), that is one approximate measure up of the relative damage done by the radiation. These are connected by:

< extnumber that rems= extRBE imes extnumber the rads labelEq2>

with RBE approximately 10 because that α radiation, 2(+) because that protons and neutrons, and 1 for β and γ radiation.