REVISION OF RADIOISOTOPES POST AFTER LECTURE 

Radioisotopes- they are atoms that contain unstable combinations of protons and neutrons. protons have a postive charge repels the neutrons. this will push the atome nuclues apart and breaking the binding energy. they have the same atomic number but different mass numbers. same PROTONS but different NEUTRONS. 

protons= smaller number. 

neutrons- atomic number - proton number 

radioactivity- the process of spontaneous disintegration of atomic nuclei and emerssion of energy. unstable atom have excess energy and the atom that rids itself of its extra energy gives it off in electromagnetic waves called radiation.  

half life - the amount of time required for radioactivity to be reduced by 50%. the time taken for half of the radioisotope to dissappear. half-life can be used to determine approximately how many atoms of an isotope can decay in a certain time period - which in turn allows us to know how much energy is released in that time period due to the decay.

inverse sqaure law - the intensity of radiation in terms of dose rate is inversely proportional to the square of the disance

Alpha decay-  same make up as helium atom with 2 neutrons and protons with postiive charges and low penetrating power. can only pass through paper, measured by a gieger counter- device that gets used to measure the energy of ionizing radiation in an area. 

-do not penetrate skin and cause no damage to tissues below

-cannot even penetrate paper 

BETA decay -negative one charge same as electron. stopped by aluminium sheets or few centimeters of plastic or a few millimeters of metal.

GAMMA decay - waves and not particles, no mass no charge. stopped by only thick lead or concrete more than 7cm. emitted together with alpha and beta particles. 

Hazards of Alpha Radiation 

1) Since alpha particles cannot penetrate the dead layer of the skin, they do not present a hazard from  exposure external to the body. 

2) serious hazard when they are in close proximity to cells and tissues such as the lung. Special precautions are taken to ensure that alpha emitters are not inhaled, ingested or injected.

 Hazards of Beta radiation 

1) larger penetrating power and can cause higher external damage to the skin and affect cells inside our bodies.

2)  do have more penetrating power, which means that they can get through your skin and affect cells inside you. 

3) if the struck molecule is DNA material that predisposes to a mutation. Beta radiaiton is used in radiotherapy to kill cancerous cells. They can penetrate the layer of cells where new skin cells are produced, and prolonged localized exposure can cause skin injury.

 Hazards of Gamma Radiation 

1) Gamma rays do not ionize at all and does not cause damage directly. 

2) Once absorbed by an atom, it gains alot of energy and may emit other particles.  It carries so much energy it may harm the surrounding viable cells. 

3) Gamma rays are very pentrating and exposure may cause damage through external diffusion. 

4) They are very damaging to rapidly diving cells, and prolonged exposure can lead to burning of the skin and irreversible damage to internal tissue and organs. Chromosomes maybe affected and high levels can even be fatal.

reducing radioisotope hazards 

Time:  The time of exposure to penetrating radiation can be reduced by planning operations or by using special procedures during operations.

 
Planning Operations 

 
• Review the safety aspects of the operation in detail.
• Carry out trial runs with no or low levels of radioactivity.
• Design operations to be a sequence of simple steps that
can be accomplished quickly and safely.
• Adjust equipment to ensure that you are comfortable
when handling radioactivity.

During the Operation

• Equipment should be assembled before introducing the
radiation source.
• The dose rates at various steps in the operation should
be monitored or known to ensure that effort is concentrated to reduce time of working in high radiation fields.
• Operations that do not require proximity to radioactive
materials – for example, paperwork or resting – should
be carried out away from the radiation areas.
• Regularly monitor and promptly remove contaminated
gloves.

Distance

 Ionizing radiation spreads through space like light or heat. Generally, the farther you are from a source of radiation the lower your dose rate.
Distance is very useful for protection when handling physically small sources. The dose rate from a small source is inversely proportional to the square of the distance from the
source.
This “inverse square law” means, for example, that if the distance from the source is doubled, the dose rate will be one fourth.

Shielding
Dense materials with high atomic numbers, such as lead, form the most effective and compact shields for small sources of penetrating radiation.

Methods for Reducing Exposure

• Store radioactive materials emitting penetrating radiation in lead containers with lead lids.
• Where space permits, concrete blocks may be used to enclose a radioactive storage area.
• Whenever practical, use dilute solutions of high energybeta-emitting radionuclides since the larger volume of liquid will effectively absorb more of the beta rays.

 
Preventing Inhalation
Inhalation intakes can be prevented by ensuring that radioactive materials are secured in sealed containers.
 Fume hoods provide protection by drawing air past the worker into an enclosure and safely exhausting it.

Preventing Skin Absorption
 Additional protection can be provided by using splash guards and by wearing gloves, a lab coat and other protective clothing.Avoid sharp objects and handle syringes carefully to prevent
inadvertent self-injection.

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