A patient receives
A rad of radiation as part of her treatment and absorbs
E J of energy. The RBE of the radiation particles is
R . If the RBE is increased to 1.5
R , what will be the energy absorbed by the patient?
If a 90-kg person is exposed to 50 mrem of alpha particles (with RBE of 16), calculate the dosage (in rad) received by the person. What is the amount of energy absorbed by the person?
The biological effects of ionizing radiation are due to two effects it has on cells: interference with cell reproduction, and destruction of cell function.
A radiation dose unit called the rad is defined in terms of the ionizing energy deposited per kilogram of tissue:
The SI unit for radiation dose is the gray
(Gy), which is defined to be
To account for the effect of the type of particle creating the ionization, we use the relative biological effectiveness (RBE) or quality factor (QF) given in
[link] and define a unit called the roentgen equivalent man (rem) as
Particles that have short ranges or create large ionization densities have RBEs greater than unity. The SI equivalent of the rem is the sievert (Sv), defined to be
Whole-body, single-exposure doses of 0.1 Sv or less are low doses while those of 0.1 to 1 Sv are moderate, and those over 1 Sv are high doses. Some immediate radiation effects are given in
[link] . Effects due to low doses are not observed, but their risk is assumed to be directly proportional to those of high doses, an assumption known as the linear hypothesis. Long-term effects are cancer deaths at the rate of
and genetic defects at roughly one-third this rate. Background radiation doses and sources are given in
[link] . World-wide average radiation exposure from natural sources, including radon, is about 3 mSv, or 300 mrem. Radiation protection utilizes shielding, distance, and time to limit exposure.
Conceptual questions
Isotopes that emit
radiation are relatively safe outside the body and exceptionally hazardous inside. Yet those that emit
radiation are hazardous outside and inside. Explain why.
The RBE for low-energy
s is 1.7, whereas that for higher-energy
s is only 1. Explain why, considering how the range of radiation depends on its energy.
Which methods of radiation protection were used in the device shown in the first photo in
[link] ? Which were used in the situation shown in the second photo?
What radioisotope could be a problem in homes built of cinder blocks made from uranium mine tailings? (This is true of homes and schools in certain regions near uranium mines.)
Find the radiation dose in Gy for: (a) A 10-mSv fluoroscopic x-ray series. (b) 50 mSv of skin exposure by an
emitter. (c) 160 mSv of
and
rays from the
in your body.
One half the
rays from
are absorbed by a 0.170-mm-thick lead shielding. Half of the
rays that pass through the first layer of lead are absorbed in a second layer of equal thickness. What thickness of lead will absorb all but one in 1000 of these
rays?
A plumber at a nuclear power plant receives a whole-body dose of 30 mSv in 15 minutes while repairing a crucial valve. Find the radiation-induced yearly risk of death from cancer and the chance of genetic defect from this maximum allowable exposure.
In the 1980s, the term picowave was used to describe food irradiation in order to overcome public resistance by playing on the well-known safety of microwave radiation. Find the energy in MeV of a photon having a wavelength of a picometer.
Bacteria doesn't produce energy they are dependent upon their substrate in case of lack of nutrients they are able to make spores which helps them to sustain in harsh environments
_Adnan
But not all bacteria make spores, l mean Eukaryotic cells have Mitochondria which acts as powerhouse for them, since bacteria don't have it, what is the substitution for it?
Assimilatory nitrate reduction is a process that occurs in some microorganisms, such as bacteria and archaea, in which nitrate (NO3-) is reduced to nitrite (NO2-), and then further reduced to ammonia (NH3).
Elkana
This process is called assimilatory nitrate reduction because the nitrogen that is produced is incorporated in the cells of microorganisms where it can be used in the synthesis of amino acids and other nitrogen products
There are nothing like emergency disease but there are some common medical emergency which can occur simultaneously like Bleeding,heart attack,Breathing difficulties,severe pain heart stock.Hope you will get my point .Have a nice day ❣️
_Adnan
define infection ,prevention and control
Innocent
I think infection prevention and control is the avoidance of all things we do that gives out break of infections and promotion of health practices that promote life