INAYA MEDICAL COLLEGE (IMC) RAD 232 - LECTURE 1 RADIATION PHYSICS DR. MOHAMMED MOSTAFA EMAM
LECTURES & CLASS ACTIVITIES https://inayacollegedrmohammedemam.wordpress.com/ Password: drmohammedemam 16-02-2015 DR. MOHAMMED MOSTAFA EMAM 2
Radiation: It is defined as the process by which energy is emitted from a source and propagated through the surrounding medium. 16-02-2015 DR. MOHAMMED MOSTAFA EMAM 3
NUCLEUS CHARACTERISTICS This appear is a nucleus; the red ones are going to be the protons and the blue ones are going to be the neutrons. 16-02-2015 DR. MOHAMMED MOSTAFA EMAM 4
NUCLEUS CHARACTERISTICS If we look at the periodic table, we can see neon has same number of proton and neutron, similar way calcium also have same no. of neutrons and protons. Stable atoms 16-02-2015 DR. MOHAMMED MOSTAFA EMAM 5
NUCLEUS CHARACTERISTICS Uranium have 92P and 146N. Why is that??? Nucleus is held together by a strong nuclear force; All these nucleons are held together by this force (came from neutrons) which hold the nucleus together. 16-02-2015 DR. MOHAMMED MOSTAFA EMAM 6
Radioactivity : It is the act of emitting radiation spontaneously from the unstable atoms. Unstable atoms differ from stable atoms because they have an excess of energy or mass or both. Unstable atoms are known as radioactive atoms. E.g. Carbon 14, Uranium 238 16-02-2015 DR. MOHAMMED MOSTAFA EMAM 7
16-02-2015 DR. MOHAMMED MOSTAFA EMAM 8
CLASSIFICATION OF RADIATION Radiation Non-ionizing Ionizing Directly ionizing (charged particles: electrons, protons, etc Indirectly ionizing (neutral particles: photons, neutrons. 16-02-2015 DR. MOHAMMED MOSTAFA EMAM 9
NON-IONIZING RADIATION Non-ionizing radiation refers to any type of electromagnetic radiation that does not carry enough energy to ionize an atom or molecule. Examples: Near ultraviolet radiation infrared radiation, microwave, radio waves, etc 16-02-2015 DR. MOHAMMED MOSTAFA EMAM 10
IONIZING RADIATION Ionizing radiation has sufficient energy to ionize an atom or molecule. Ionization is a process in which a charged portion of a molecule (usually electron) is given enough energy to break away from the atom. Ionization results in the formation of charged particles or ions; the molecule with net positive charge and the free electron with a net negative charge. All ionizing radiation is capable, directly and indirectly of removing electrons from most of the molecules. Ionizing radiation has enough energy to damage DNA in cells which in turn may lead to cancer. 16-02-2015 DR. MOHAMMED MOSTAFA EMAM 11
ALPHA RADIATION 16-02-2015 DR. MOHAMMED MOSTAFA EMAM 12
16-02-2015 DR. MOHAMMED MOSTAFA EMAM 13
Characteristics of alpha radiation: Alpha radiation is not able to penetrate skin. Alpha emitting materials can be harmful to humans if the materials are inhaled, swallowed or absorbed through open wounds. 16-02-2015 DR. MOHAMMED MOSTAFA EMAM 14
Characteristics of alpha radiation: Alpha radiation is not able to penetrate skin. Alpha radiation is the least penetrating. It can be stopped (or absorbed) by a sheet of paper. 16-02-2015 DR. MOHAMMED MOSTAFA EMAM 15
Characteristics of alpha radiation: When alpha particles are emitted outside our bodies, virtually all of their ionizing radiation is harmlessly absorbed by the nonliving outer layer of our skin. This means that alpha radiation doesn t have much effect on our health unless radioactive isotopes get inside our bodies and emit radiation internally. 16-02-2015 DR. MOHAMMED MOSTAFA EMAM 16
Alpha radiation travels a very short distance through air. A variety of instruments have been designed to measure alpha radiation. Instruments can not detect alpha radiation even a thin layer of water, blood, dust, paper or other material, because alpha radiation is not penetrating 16-02-2015 DR. MOHAMMED MOSTAFA EMAM 17
USES OF ALPHA RADIATIONS Alpha particles are most commonly used in smoke alarms (smoke detectors). The alpha particles ionize air between a small gap. A small current is pass through the ionized air. Smoke particles from fire that enter the air gap reduces the current flow, sounding the alarm. Alpha decay can produce safe power sources for radioisotope thermoelectric generators used for space probes and artificial heart pacemakers. 16-02-2015 DR. MOHAMMED MOSTAFA EMAM 18
BETA RADIATION Beta radiation is a stream of electrons called beta particles. When a beta particle is ejected, a neutron in the nucleus is converted to a proton, so the mass number of nucleus is unchanged, but the atomic number increases by one unit. 16-02-2015 DR. MOHAMMED MOSTAFA EMAM 19
Thorium undergoes radioactive decay to form Protactinium and beta particle. 16-02-2015 DR. MOHAMMED MOSTAFA EMAM 20
Characteristics of beta radiation: Beta radiation is more hazardous because it can also cause ionization of living cells. If the particles hits a molecule of DNA it can cause spontaneous mutation and cancer. 16-02-2015 DR. MOHAMMED MOSTAFA EMAM 21
Characteristics of beta radiation: Beta emitting contaminants may be harmful if deposited internally. Beta radiation may travel meters in air and is moderately penetrating, so It can penetrate human skin to germinal layer where new cells are produced. 16-02-2015 DR. MOHAMMED MOSTAFA EMAM 22
Characteristics of beta radiation: Beta radiation is more hazardous because it can also cause ionization of living cells. If the particles hits a molecule of DNA it can cause spontaneous mutation and cancer. 16-02-2015 DR. MOHAMMED MOSTAFA EMAM 23
Characteristics of beta radiation: Beta radiation is more hazardous because it can also cause ionization of living cells. If the particles hits a molecule of DNA it can cause spontaneous mutation and cancer. 16-02-2015 DR. MOHAMMED MOSTAFA EMAM 24
Beta radiation cannot be detected with an ionization chamber such as a CD V-715. Clothing and turnout gear provide some protection against most beta radiation. Turnout gear and dry clothing can keep beta emitters off of the skin. 16-02-2015 DR. MOHAMMED MOSTAFA EMAM 25
USES OF BETA RADIATIONS Beta radiation are widely used in medicine. In brachytherapy, beta radioisotopes can be used to irradiate areas inside a patient to prevent the growth of certain tissues. Beta particles are also used in some forms of therapy to kill cancer cells. 16-02-2015 DR. MOHAMMED MOSTAFA EMAM 26
USES OF BETA RADIATIONS Brachytherapy is a procedure that involves placing radioactive material inside your body. Brachytherapy is one type of radiation therapy that's used to treat cancer. 16-02-2015 DR. MOHAMMED MOSTAFA EMAM 27
USES OF BETA RADIATIONS Brachytherapy is sometimes called internal radiation. Brachytherapy allows doctors to deliver higher doses of radiation to more-specific areas of the body, compared with the conventional form of radiation therapy (external beam radiation) that projects radiation from a machine outside of your body. 16-02-2015 DR. MOHAMMED MOSTAFA EMAM 28
USES OF BETA RADIATIONS Brachytherapy may cause fewer side effects than does external beam radiation, and the overall treatment time is usually shorter with brachytherapy. 16-02-2015 DR. MOHAMMED MOSTAFA EMAM 29
USES OF BETA RADIATIONS Beta radiation is used in leak detection in the pipeline. This is achieved by adding small amount of beta radiation to the fluid. The area above the ground where high intensity of beta radiation is detected will pin point the leak sources in the pipeline. 16-02-2015 DR. MOHAMMED MOSTAFA EMAM 30
USES OF BETA RADIATIONS Carbon-14 is used as tracers in chemical and biological research. The age of the ancient organic materials can also be found by measuring the amount of Carbon-14 that is left. 16-02-2015 DR. MOHAMMED MOSTAFA EMAM 31
GAMMA RADIATION Gamma radiation is electromagnetic radiation of high frequency and therefore high photons with a very short wavelength. 16-02-2015 DR. MOHAMMED MOSTAFA EMAM 32
GAMMA RADIATION The emission of gamma radiation results from an energy change within the atomic nucleus. 16-02-2015 DR. MOHAMMED MOSTAFA EMAM 33
GAMMA RADIATION It should be noted that the emission of gamma rays does not change the mass number or atomic number of the nucleus. 16-02-2015 DR. MOHAMMED MOSTAFA EMAM 34
GAMMA RADIATION Alpha and beta emission are often accompanied by gamma emission, as an excited nucleus drops to a lower and more stable energy change. 16-02-2015 DR. MOHAMMED MOSTAFA EMAM 35
X-RAYS X-ray photons carry enough energy to ionize atoms and disrupt molecular bond. This makes it a type of ionizing radiation and thereby harmful to living tissues. X-ray machine sends individual x-ray particles through the body. The image is recorded on a computer or film. 16-02-2015 DR. MOHAMMED MOSTAFA EMAM 36
Characteristics of gamma radiation and x-rays: Gamma radiation and X-rays are electromagnetic radiation like visible light, radio waves, and ultraviolet light. These electromagnetic radiations differ only in the amount of energy they have. Gamma rays and X-rays are the most energetic of these. X-rays are like gamma rays. They, too, are penetrating radiation. 16-02-2015 DR. MOHAMMED MOSTAFA EMAM 37
Gamma radiation is able to travel many meters in air and many centimeters in human tissue. Radioactive materials that emit gamma radiation and X-rays constitute both an external and internal hazard to humans Gamma radiation or X-rays frequently accompany the emission of alpha and beta radiation 16-02-2015 DR. MOHAMMED MOSTAFA EMAM 38
Gamma radiation is detected with survey instruments, including civil defense instruments. Low levels can be measured with a standard Geiger counter, such as the CD V-700. High levels can be measured with an ionization chamber, such as a CD V-715. Instruments designed solely for alpha detection will not detect gamma radiation Pocket chamber (pencil) dosimeters, film badges, thermo luminescent, and other types of dosimeters can be used to measure accumulated exposure to gamma radiation. 16-02-2015 DR. MOHAMMED MOSTAFA EMAM 39
USES OF GAMMA RADIATIONS Even after it has been packaged, gamma rays can be used to kill bacteria, mould and insects in food. This process prolongs the shelf-life of the food, but sometimes changes the taste. Gamma rays are also used to sterilise hospital equipment, especially plastic syringes that would be damaged if heated. 16-02-2015 DR. MOHAMMED MOSTAFA EMAM 40
The most common tracer is called Technetium-99 and is very safe because it only emits gamma rays and doesn't cause much ionization. Radioisotopes can be used for medical purposes, such as checking for a blocked kidney. To do this a small amount of Iodine-123 is injected into the patient, after 5 minutes 2 Geiger counters are placed over the kidneys. Also radioisotopes are used in industry, to detect leaking pipes. To do this, a small amount is injected into the pipe. It is then detected with a GM counter above ground. 16-02-2015 DR. MOHAMMED MOSTAFA EMAM 41
Checking welds. If a gamma source is placed on one side of the welded metal, and a photographic film on the other side, weak points or air bubbles will show up on the film, like an X-ray. Because Gamma rays can kill living cells, they are used to kill cancer cells without having to resort to difficult surgery. This is called "Radiotherapy", and works because cancer cells can't repair themselves when damaged by gamma rays, as healthy cells can 16-02-2015 DR. MOHAMMED MOSTAFA EMAM 42
USES OF X-RAYS X-rays are used in medicine for medical analysis. Dentists use them to find complications, cavities and impacted teeth. Soft body tissue are transparent to the waves. Bones also block the rays. X-rays are used in industry to inspect products made by various kinds of materials. X-ray machines are used in airports to check luggage etc. 16-02-2015 DR. MOHAMMED MOSTAFA EMAM 43
In Science x-rays are used to analyze the arrangement of atoms in many kinds of substances, particularly crystals. Archaeologists used X-rays to examine ancient objects covered by a crust of dirt. X-rays are also used in consumer goods the manufactures treat certain kinds of plastic to check the quality of many mass produced products. 16-02-2015 DR. MOHAMMED MOSTAFA EMAM 44