Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Radiation in medicine > Week 2: Effects of radiation on the body > Flashcards

Week 2: Effects of radiation on the body Flashcards

1
Q

Measuring radiation

A
  • Becquerel (Bq) = The SI unit of radioactivity equal to 1 disintegration per second
  • Curie (Ci) = The traditional unit of radioactivity, equal to the radioactivity of 1g of pure radium-266, no used anymore
  • Gray (Gy) = Equal to 1 joule of radiation absorbed per kg
  • Sievert (Sv) = The SI unit for the amount of radiation roughly equivalent in biological effectiveness to 1 Gy
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Absorbed dose

A

The concentration of energy deposited in tissue as a result of an exposure to ionising radiation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Equivalent Dose

A

A calculation that is based on the properties of different types of radiation, basing it on Absorbed dose and relative biological effectiveness
Only calcualted for individual organs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Effective Dose

A

It is the addition of equivalent doses to all organs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Radiosensitivity

A
  • The probability of a cell, tissue or organ suffering an effeft per unit dose of radiation
  • Radiosensitivity is highest in cells that are highly mitotic or undifferentiated
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

High radiosensitive cells

A

Basal epidermidis
Bone marrow
Thymus
Gonads
Lens cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Low radiosensitivity cells

A

Muscles
Bone
Nervous system tissues

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Determinants of biological effects from radiation

A
  • Dose
  • Type of radiation
  • Area exposed
  • Cell sensitivity
  • Individual sensitivity
  • Rate of absorption
  • Rate of expulson
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Effective half life

A
  • Considers biology + physical half life by the equation:
    1/T Effective = 1/T Physical + 1/T Biological
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Changes to the cell environment using radiation

A
  • Directly affects pH with more OH-
  • Affects lipid bilayer + ionic pumps
  • Proteins changes inpermeability
  • Equilibrium of the cell is shifted
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Unstable chromosomal aberrations/mutations

A
  • Leads to cell death majority of the time
  • Examples of unstable mutations:
    + Dicentrics
    + Ring chromosomes
    + Large deletions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Stable chromosomal aberrations/mutations

A
  • Does not prevent the cell from dividing
  • Examples of stable mutations:
    + Small deletions
    + Aneuploidy (Abnormal number of chromosomes in haploid cells)
    + Reciprocoal transolcations
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Transmissible genomic instability

A
  • Persistent enhancement in rate of genetic changes arise in the descendents of irradiated cells after many gneerations of replication
  • Cell lineage could acquire multiple sequential + interacting gene mutations to create a malignant cell
  • Epigenetics can be affected ie hypomethylation, hypoacetylation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How do cells die after irradiation?

A
  • A result from changes in DNA or biochemistry
  • Most is via mitotic catastropher at interphase
  • Steps:
    + Division ceases
    + Chromatin degradation
    + Shrinkage + nuclear lysis
  • Occurs in tissues with high turnover rates ie bone marrow + mucosal linings
  • In foetus’, they can 1st trImester congenital abnormalities
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Apoptosis-inducing factors

A
  • DNA damage
  • Endoplasmic reticulum stress
  • Microtubule damage
  • Surrounding microenvironment
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Necrosis necroptosis

A
  • Active cell death
  • Triggered by disruption of homeostasis internally + externally
  • Oxidative stress + peroxidation of the cell
17
Q

Autophagy

A
  • Recycles damaged proteins + cell organelles
  • Induced by oxidative stress + endoplasmic reticulum stress + mitochondrial damage
  • DNA damage can lead to nuclear autophagy
  • Protein folding can cause autophagy
  • Linked to radio- + chemo-resistance
18
Q

Effects of ionising radiation on the human body

A
  • Divided into 2 types
    + Non-stochastic/deterministic
    + Stochastic effects
19
Q

Non-stochastic effects

A
  • Believed to be a threshold of radiation
  • Severity increases as dose increases
  • Caused significant cell damage/death
  • Cell death causes functional impairment of a tissue/organ
  • Although relatively rare, deterministic effects secodnary to diagnostic imaging do occasionally occur
20
Q

Example of deterministic effects of ionising radiation

A
  • Radiotherapy cycle
  • Cataract formation
  • Sterility
  • Haematopoietic symptoms
  • GI effects
  • Hair
  • Brain + Nervous system
  • Thyroid
21
Q

Stochastic effects

A
  • Follows a linear no-threshold hypothesis
  • Risk of an effect occuring increases linearly as dose increases
  • A lot of radiation can become cumulative with anecdotal evidence
22
Q

Example doses for radiotherapy

A
  • Stage 1 lung cancer = 54 Gy total given over 3 sessions
  • Stage 3 lung cancer = 60 Gytotal given over 30 sessions
  • Stage 1 breast cancer = 40 Gy total given over 15 sessions
  • Stage 4 prostate cancer, metastasised to bone = 8 Gy total over in 1 session
23
Q

Risks of radiotherapy

A
  • Generally a 6 week course, daily
  • Acute effects can include loss of appetite, nausea, skin damage, hair loss, tiredness + fatigue
  • Later side-effects: Fibrosis, weakened bones, cancers, CNS damage
24
Q

Acute Radiation Syndrome

A
  • Radiation toxicity that has been evidenced from Japan + Chernobyl incidences
  • High dose within a short period of time
  • > 0.7 Gy
  • > 5 Gy of high energy radiation can lead to death within 14 days
25
Q

4 stages of of Acute Radiation Syndrome

A
  • Prodromal stage - Minutes to days following exposure, where nausea, vomiting, headaches, anorexia, maybe diarrhoea
  • Latent stage - Few hours up to a few weeks after exposure, where the patient will look and feel gneerally healthy
  • Illness manifestation stage - Hours to several months, where sympoms occur depending the specific syndrome
  • Recovery or death - Can be several weeks to 2 years, most patients who don’t recover die within several montsh of exposure

Radiation in medicine (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions