Radiation Biology unit 2, 1st slides

At the atomic level, what are the interactions

no interaction, absorption or photoelectric effect, compton scatter, & coherent scatter 

No interaction-

When an x-ray photon passes through an atom unchanged, no interaction has  taken place

Compton Scatter

When an x-ray photon collides with an outer- shell electron and ejects the electron from its orbit 

Compton scatter results:

The photon is scattered in a different direction at a lower 
energy 

What's a Compton?

 the ejected electron 

Coherent Scatter-

When an x-ray photon is scattered and no loss of energy occurs  

where THERE IS NO IONZATION IN?  

COHERENT SCATTER 

Compton and coherent scatter are both?

Secondary radaiton, are traveling when they are deflected into matter (the patient’s head) 

What stands out about compton?

It has ionziation and more common in dnetisry

What kind of radition can we proect our patients from? 

Secindary radiation 

Radiation is from where?

Manmade and and narual resources 

Manmade resources of radiation?

Computer, watch, imaging 

Natrual resources of radiation are?

From food like potassium, brazillan nuts have radon 

What is most in the US natrual source of radiation?  

Radon 

Most manmade resource of radtion?

Medical imaging 

Define radon?

A carcinogen, Odorless, colorless, toxic gas

 
What can radon do?

 
Seep into homes 

 Radon is Leading cause of?

 
lung cancer in non-smokers 

What kind of waves does ionzing radiation have?

Short 

The higher the elevation,

the more radiation you get from the sun (someone who lives in denver) 

Who kind of person is getting alot radiation exposure?

A traveler who gets imagging done  

How to measure raditon?

millirem 

Where does radon come form?

The decay of rocks 

Considers radon as a carcinogen?

The epa 

What to do if you get excessive radon in home?

get a mitigation test 

Where is radon common in?  

Ky  

 

What is the leading cuase of radon?

Medical 

Why is ALL ionizing radiation harmful?

It may lead produce biologic changes in living tissue  

What is ionizing radiation?

The removal of electrons 

Absorption

is the total transfer of energy from the x-ray photon to the patient tissues 

Radiatioan biology-

the effects of ionizing radiation on living tissue 

What are the results of biologic changes due to radiation?

Poor health

Does biologic damage= poor health?

no but it can lead to poor health outcomes  

How is radiation used in medicine?

For diagnostic & therapeutic  

What does diagnostic radiation look like in dentistry?

Imaging to look for carious lesions, pathologies, & evaluate bone levels

What does diagnostic radiation look like medically?

X-ray of areas of the body 

What does theraputic radiation look like?

radiation therapies to treat different leukemias or cancers 

What do cells do when they have interacted with ionizing radiation?

The atoms in the cells form ions 

What happeneds after cells have interacted with ionizing radiation?

leads to no change in cells, a change in the cell Or cell they can die  

What happens if the cell dies?

It may or may not be replaced depending on several of factors 

What if the cell changes?

It can reproduce

What happens if cell reproduces because it changed after interacting with ionizing radiation?

may produce a benign or a malignant growth 

What if the cell does not changes?

Nothing haPPENS 

Do all x rays reach the image reecptor?

No, they are abosrbed by the patient’s tissues 

What happnes with sbosrption?

chemical changes occur that result in biologic damage and 
possibly poor health outcomes 

The mechanism of radiation injury?  

Ionization and free radical 

in mechanisms of injury, What happens to the electron that gets dislodged by radiation?

It interacts with other atoms in the tissue. 

In mechanisms of injury, What does the kinetic energy of the dislodged electron cause?

It creates further ionization and breaks molecular bonds within the cell

In mechanisms of injury, What is the result of molecular bonds breaking inside a cell?

It leads to biological change. 

In mechanisms of injury, Can these biological changes always be severe?,

No, they may have little impact or can cause profound effects that result in poor health outcomes which dependent on factors 

In mechanisms of injury, What is the chain reaction caused by radiation knocking out one electron?

The dislodged electron causes more ionizations and bond breakage, spreading damage in tissue. 

Are free radical unstable?

Yes, but they are working to become stable 

Free radical formation?

occurs when the x-ray photon ionizes water 

In Free Radical Formation, What does ionization of water produce?

Hydrogen and hydroxyl free radicals. 

What is a free radical?

An uncharged atom or molecule with a single, unpaired electron in the outermost shell. 

Why are free radicals unstable and highly reactive?

Because they have an unpaired electron. 

When will the limited area-low dose results appear?

after years or generations, linked to cancer, birth abnormalities, and genetic defect 

Limited area low dose example?

Diagnostic radiographs 

Since limited area low dose has a LACK OF RESARCRH,

implement radiation safety procedures and use necessary precautions for the patient and radiographer 

Limited area- low dose

Small amounts absorbed overtime

What’s scary about erythema?

Skin can break which will allow the patient to be more susceptible to infection 

Erythema-

painful reddening of the skin which will last about 2-4 week after RADIATION treatment  

Raditaion theray can cause?  

acute radiation sickness, sickness, sever vomiting, diarrhea, hair loss, erythema 

Success rate of radiation therapy is dependent on?

the radiosensitivity of the cell

When it comes to Limited Area – High Dose think of,

Radiation therapy 

Limited area- high dose-

focusing on a specific area and its getting alot of radiation with the hope to cure the poor health outcome there is 

When we do FINALLY see signs of the whole body-low dose, what does it look like?

Increased rates of leukemia and tumors & reduced life longevity 

Examples of whole body-low dose?

Natural background radiation & Environmental pollution 

Whole body- low dose?

Our whole body reciving radiation, but in low amounts & a very long latent period like up to 20 years..... 

Examples of whole-high dose?

Nuclear warfare, nuclear accident, Chernobyl & Occupational hazard 

Whole body- high dose 

your whole body is receiving radiation and a lot of radiation all at once 

What happens if critical organs are damaged?

diminished quality of life for the individual 

What’s going on with critical organs?

They are exposed to more radiation than others during imaging 
procedures 

Why would bone marrow be very susceptible to radiation exposure?

There are immature cells in the bone marrow 

When there’s a higher cell metabolism

that cell will be more sensitive to radiation exposure 

Mitotic Activity

cell division, the more frequent, more sensitive 

Cell Differentiation

immature (typically found in bone marrow) or not  highly specialized, more sensitive 

Cell Metabolism

all of those chemical reactions that occur in living organisms  

Factors that make cells more responsive to radiation-

mitotic activity, cell differenetaiton, & cell metabolism 

Radiosensitive

A cell that is sensitive to radiation 

radioresistant

A cell that is less sensitive to radiation exposure 

The result with genetic effects?

genetic damage cannot be repaired 

If the damages occur in reprdouctive/germs cells?,

Irradiated person does not suffer from radiation injury, instead The offspring will suffer from cellular mutations 

if the damage occurs in SOMATIC NOT All cells?

Damage will be seen in the person being irradiated person and Not passed on to offspring 

Examples of somatic effects

cataracts, cancer, leukemia & hair loss  

Areas that are Radioresistant?

Salivary glands, thyroid, liver, & kidneys, mature bone 

critical organs in dentistry

lens 0f the eye, Bone marrow,skin & thyroid 

Areas that are radiosensitive to radiation?  

blood cells, reproductive cells, Bone marrow, intestinal mucosa,  

Which age group is more suspectable to radiation injury?

Children  

Total dose

amount of radiation received, or total amount of radiation absorbed 

Dose rate

rate at which exposure to radiation occurs and absorption takes place (dose/time) 

Amount of tissue irradiated

area of the body exposed to radiation 

 
Cell sensitivity

the level at which each cell is sensitive to radiation 

Age:

the age of the individual being irradiated 

Factors that influence how cells react to radiation injury

total dose, dose rate, amount of tissue irradiated, cell sensitivity, & age  

Yes or no? The cells that aren't able to repair or that repair inappropriately will accumulate in the tissue which lead to poor health outcomes 

yass

Cumulative effect

unrepaired damage to the cells accumulates in the tissue and this damage is additive 

Why is radiation damaging/ why are there poor health outcomes due to radiation exposure?

cumulative effect 

Latent period

time cell is exposed to ionizing radiation to the appearance of clinical signs & varies in time 

Period of injury

time when cellular changes occur (cell death, cell injury)