Summary of Chapter 7 (Molecular and Cellular Biology)

2 Protons and 2 Neutrons

What are alpha particles made up of?

Alpha particle

consists of 2 protons and 2 neutrons; very heavy; causes superficial/skin damage; can be stopped by black construction paper

Superficial/skin damage

What type of damage do alpha particles cause?

Black construction paper

What can stop alpha particles?

Ionization

Instability of an atom caused by addition or removal of electrons

Linear Energy Transfer (LET)

Amount of energy deposited in a tissue over path of radiation beam

Low LET

when radiation deposits little energy in tissues; x-rays and gamma rays

X-rays and gamma rays

What are two types of radiation that cause Low LET?

alpha

What’s a type of radiation that results in High LET?

High LET

When radiation deposits greater energy in tissue; alpha

Prostate Seeds

What’s a type of LET used in Nuclear Medicine that’s implanted?

Implanted, ingested, injected, or inhaled

High LET is potentially dangerous if ______________ (Prostate seeds) or ______________, ______________, or ______________ in Nuclear Medicine

Relative Biologic Effectiveness (RBE)

relative damage to tissues due to radiation being deposited

directly

LET and RBE are directly or indirectly proportional?

(Air Kerma) or Gray (Gy)/Rad

used to measure amount of radiation deposited in ANY object whether living or inanimate

Gray

What’s the SI unit for Rads?

Rad

What’s the traditional unit for Gray?

Radiation Absorbed Dose

This is what RAD stands for when measuring amount of radiation deposited in any living tissue.

Seivert (Sv)/Rem

What are the units used to measure radiation absorbed in HUMAN tissue only?

Seivert

What is the SI unit for Rems?

Rems

What’s the traditional unit for Seivert?

Radiation Equivalent to Man

What does REM stand for when you’re measuring radiation absorbed in HUMAN tissue?

Coulombs/Kg (C/Kg); Roentgen (R)

Measure of ionization IN AIR or IN AIR exposure

Air Kerma

Rads can also be measured in ______________?

2.58 × 10^-4 C/Kg

1 Roentgen equals how many Coulombs/Kg?

Becquerel (Bq)/Curie

Used to measure radioactivity (Usually in nuclear medicine)

Coulombs/Kg

What’s the SI unit for Roentgen?

Roentgen

What’s the traditional unit for Coulombs/Kg?

Becquerel

What’s the SI unit for Curies?

Curie

What’s the traditional unit for Bequerels?

Seiverts = Gray x QF

How to find the dose equivalent in seiverts?

Rems = Rads x QF

How to find the dose equivalent in Rems?

SI x 100

How do you convert the SI unit to a traditional unit?

1

X-rays, beta particles, gamma rays have a quality factor of ______________

20

Alpha particles and fast neutrons have a quality factor of ______________

Radiation Weighting Factor

Quality factor is similar to ______________

Oxygen enhancement ratio (OER)

Tissue irradiated under oxygenated or aerobic conditions is MORE sensitive to radiation than when irradiated under anoxic or hypoxic conditions

Radiation therapy

OER is important to understand in ______________ because healthy, oxygenated tissue may not require as much radiation to kill cancer cells

Law of Bergonie & Tibondeau

young cells are more vulnerable to radiation damage; stem, immature, precursor, or undifferentiated cells

5%

DIRECT action of damage to cells from radiation occurs ______________ of the time (direct hit to DNA)

95%

INDIRECT action of damage to cells from radiation occurs ______________ of the time (due to radiolysis of water)

direct hit to DNA; radiolysis of water

Direct action is a ______________; Indirect action is due to ______________

Free radicals

Radiolysis of water can result in formation of ______________ (*) which are extremely unstable, can travel and cause point lesions away from area that was irradiated

Hydroxyl Radical (OH*) and Hydroperoxyl Radical (HO₂)

What are the 2 types of free radicals that are formed due to the radiolysis of water?

Hydrogen Peroxide (H₂O₂)

Two hydroxyl (OH*) radicals can combine to form ______________ which is toxic to the cell

Hydroxyl (OH*)

2 of what type of radicals can combine to form hydrogen peroxide (H₂O₂)

Point mutation

When radiation interacts with DNA and severs a side rail or rung of the DNA ladder; can sometimes be reversed by repair enzymes

Repair enzymes

What are the structures that can fix some point mutations?

Karotype

photomicrograph of chromosome that shows damage from radiation

DNA

Mastermind of cell and necessary for cell survival

0.25 (Gy)/25 (Rads)

A whole body dose of ______________ depresses blood cell count (Threshold dose)

Lethal dose of 3-4 Gy (300-400 Rads) that may kill 50% of exposed population in 60 days

Describe LD 50/60

Lymphocytes

What are the MOST radiosensitive cells in the body (least radioresistant)

Adult Nerve Cells

What are the LEAST radiosensitive cells in the body (most radioresistant)

2 Gy (200 Rads)

This dose may cause temporary sterility in males and females (Threshold dose)

5 Gy (500 Rads); 5-6 Gy (500-600 Rads)

This dose may cause permanent sterility in females; What about in males? (Threshold dose)

Threshold dose

This is the amount of radiation that’s required to produce a given effect