Concept about Radiation – This book covers the entire syllabus of “Community Health Nursing” prescribed by the Universities of Bangladesh- for Basic and diploma nursing students. We tried to accommodate latest information and topics.
This book is examination friendly setup according to the teachers’ lectures and examination’s questions. At the end of the book previous university questions are given. We hope in touch with the book students’ knowledge will be upgraded and flourished. The unique way of presentation may make your reading of the book a pleasurable experience.
Concept about Radiation
Definition
The term radiation includes both electro-magnetic waves of energy (e.g.radiowaves, visible light and x-rays) and particles emitted from atmosphere under certain conditions.
Sources of radiation
Radiation is a part of man’s environment. The ‘sources of radiation to which men are exposed are divided into two groups:
A. Natural and
B. Man-made.
A. Natural radiation
1. Cosmic Radiation: The sun and stars send a constant stream of cosmic radiation to Earth, much like a steady drizzle of rain. Differences in elevation, atmospheric conditions, and the Earth’s magnetic field can change the amount (or dose) of cosmic radiation that we receive.
2. Terrestrial Radiation: The Earth itself is a source of terrestrial radiation, Radioactive materials (including uranium, thorium, and radium) exist naturally in soil and rock. Essentially all air contains radon, which is responsible for most of the dose that Americans receive each year from natural background sources. In addition, water contains small amounts of dissolved uranium and thorium, and all organic matter (both plant and animal) contains radioactive carbon and potassium.
Some of these materials are ingested with food and water, while others (such as radon) are inhaled. The dose from terrestrial sources varies in different parts of the world, but locations with higher soil concentrations of uranium and thorium generally have higher doses.
3. Internal Radiation: All people have internal radiation, mainly from radioactive potassium-40 and carbon-14 inside their bodies from birth and, therefore, are sources of exposure to others. The variation in dose from one person to another is not as great as that associated with cosmic and terrestrial sources.
4. Radon and its daughter products
B. Man-made:
1. medicine sources of ionization radiation,
2. Medical and dental: x-rays, radioisotopes
3. nuclear explosions,
4. Nuclear: Radioactive fallout due to nuclear explosions (Isotopes of carbon C14, iodine 1131, cesium Cs137, and strontium Sr90)
5. Nuclear power plants and their fuel cycle.
6. consumer products,
7. Occupational exposure
8. Miscellaneous: Television sets, cell phones, luminous wrist watches etc.
Types of ionizing radiation
The term ionizing radiation’ is applied to that radiation which has the ability to penetrate tissues and deposit its energy within them. Ionizing radiation may be classified as follows;
1. Electromagnetic radiations:
- X-rays
- Gamma rays
2. Corpuscular radiations
- Alpha-particles
- Beta particles (electrons)
- Protons
Effects of radiation
1. Biologic effects:
a. Somatic
Immediate:
- Radiation sickness
- Acute radiation syndrome
Delayed:
- Leukaemia
- Carcinogenesis
- Fetal developmental abnormalities
- Shortening of life
b. Genetic:
- Chromosome mutation.
- Point mutations.
3. Acute general effects:
a. Central nervous system syndrome (Exposure to 10,000 rads or above):
- Intraocular pressure
- Headache
- Nausea
- Vomiting
- Papilledema.
b. Gastrointestinal syndrome (Exposure to above 400 rads):
- Anorexia
- Nausea
- Vomiting
- Loose motion, mucoid stool
- Malena (sometimes).
c. Long-term or late effects
- High dose, long term exposure (X-ray, gamma-ray, ultraviolet ray):
- Cataract
- Sterility
- Low dose, long term exposure (X-ray, gamma-ray, ultraviolet ray): Aplastic anaemia
- Long term exposure to beta-ray:
- Chronic radiodermatitis
- Hyperpigmentation
- Depigmentation
- Atrophy
- Squamous cell carcinoma
- Basal cell carcinoma.
- Cancers due to radiation exposure:
- Skin – squamous cell carcinoma and basal cell carcinoma.
- Bone tumour
- Leukemia,
- Lymphoma
- Lung cancer
- Thyroid carcinoma
- Prenatal radiation effect: Various types of congenital deformation.
Acute radiation syndrome
A single exposure of a large dose of over 100 repenetrating radiation on the whole body within 1 to 2 days, results in a progressive series of signs and symptoms known as acute radiation syndrome.
The sign-symptoms of acute radiation syndrome:
- Vomiting and nausea, may be accompanied by diarrhoea and abdominal pain.
- Headache, erythema of skin and conjunctivitis.
- Loss of hair and fine desquamation of skin.
- Severe hematological damage-aplasia of bone marrow, agranulocytosis, thrombocytopenia resulting in hematological disturbances.
Radiation protection
Protection measures for external irradiation are:
- Unnecessary X-ray examinations should be avoided, especially in the case of children and pregnant women.
- Adequate control and surveillance of X-ray installations.
- Protection of workers use of lead shields and lead rubber aprons.
- Improvement in techniques.
- Workers must wear a film badge or dosimeter, which shows accumulated exposure to radiation.
- Periodic medical examinations, regular working hours, recreation and holidays must be ensured to workers.
Radiation units
The unit of radioactivity is becquerel (Bq). The activity of a radioactive material is the number, disintegration per unit of time.
1 Bq is equal to 1 disintegration per second.
Ways of measuring potency of radiation:
1. Roengen –It is the unit of exposure. It is the amount of radiation absorbed in air at a given point, i.e., number of ions produced in 1 ml of air.
2. Rad –It is the unit of absorbed dose. It is the amount of radioactive energy absorbed per
gram of tissue or any material.
3. Rem-It is the product of the absorbed dose and the modifying factors. The rem indicates the degree of potential danger to health.
SI Units of radiation
1. Coulomb per kilogram (C/Kg), it repaced the roentgen. It is the unit of exposure. 1 roentgen = 2.58 x 10 Ckg.
2. Gray (Gy), it replaced the rad. It is the unit of absorbed dose, defined as the dose of ionizing radiation that impart 1 joule of energy to 1 kg of absorbing material. 1 rad 0.01 Gy.
3. Sievert (Sv), it replaced the rem. It is the SI unit of dose equivalent. The dose equivalent of 1 sievert is equal to 100 rems.
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