7. Late effects of radiation

T/F: Effects of radiation may not be seen for months or even decades

True, those are late effects

What are the 7 late effects of radiation discussed in class

1. Skin effects

2. Cataracts

3. Lifespan shortening (radiation-induced aging)

4. Radiation induced malignancy

5. Genetic effects

6. Critical organs

7. Growth and development

What are 3 late skin effects?

1. fibrosis

2. telangiectasia 

3. skin cancer

Who developed the first cyclotron? When?

1931, university of California 

By the year __ every major university had a cyclotron for research.

1940

What late effect did early cyclotron researchers get? Why?

cataracts

they’d use fluorescent screens to guide the beam without using eye protection, staring directly at the beam

What is the latent period for cataracts

5-30 years

I can’t 53E

What is the threshold dose for cataracts?

200 cGy 

NOTE: Not the same as tolerance dose. Threshold dose is the minimum dose required to even see cataracts.

What is the TD 5/50 (tolerance dose) for cataracts?

1000

(where we see 5% incidence in 50% of the population)

A late effect of radiation is lifespan shortening (radiation-induced aging). Research indicates that, at worst, humans can expect a reduced lifespan of __ for every rad

10 days for every rad

T/F: Lifespan shortening includes radiation induced malignancies.

False: It does not count induced malignancies, just the effects of accelerated, premature aging.

Exposures of less than ___ may actually be helpful (good for you)

1 rad/ year

What are the 6 radiation induced malignancies discussed in class:

1. Stochastic effect (non-threshold effect that could happen at any dose)

2. Thyroid cancer

3. Osteosarcomas

4. Skin cancers

5. Breast cancer

6. Lung Cancer

What is the primary stochastic effect cancer of concern?

Leukemia

Latent period for leukemia:

4-7 years

but risk for approx. 20 years

4dult Leukemia

T/F: the latent period for radiation induced leukemia is much longer than the latent period for radiation-induced solid tumors

False: other way around 

____ leukemias are more prevalent in irradiated adults, while

____leukemias are more prevalent in irradiated children

adults: myeloid leukemias (AML, CML)

children: CLL

Give a historical example of radiation induced leukemias.

tx of ankylosing spondylitis patients with TSI (total spinal irradiation) in the 1940s-1950s (specially in Great Britain)

term. Ankylosing spondylitis

def. an arthritic like condition along the vertebral column that causes a painful huckaback

Give 2 examples of radiation induced thyroid cancers.

1. childhood irradiation with I131 to tx hyperthyroidism

2. Hiroshima/ Nagasaki survivors

Hyperthyroidism is treated by ablating the gland with ___ rad, but before the year___, the dose was___cGy

500 rad

1930s

1200-6000cGy

Give a historical example of radiation induced osteosarcomas

Radium watchdial workers

What is the main radiation that caused osteosarcomas in the radium watchdial workers?

alpha particles tend to get absorbed by bones

The first reported radiation-induced skin cancer was in the year ____, on the following body part____ of ____(person)

1902

hand

a radiologist

FYI: early radiologists made a habit of placing their hand in the path of the beam while observing their hands on early fluoro units

Give 2 historical examples of radiation induced breast cancer

1. Hiroshima / Nagasaki survivors

2. Canadian sanitorium patients in 1960s exposed to many fluoroscopies 

What historical exposures causes radiation-induced lung cancer

1. radon gas exposure

2. pitchblende mixing

What area of radiation-induced malignancies is the weakest in terms of our knowledge of what radiation effects can happen?

Genetic defects

Radiation induced genetic defects can happen cuz ionizing radiation can cause

chromosomal breaks

term. doubling dose

def. the dose that will produce twice the frequence of genetic mutations

as would be observed without the radiation exposure 

Critical organs include the following organs, and can cause the following effects on those organs:

1. gonads = genetic effects

2. bone marrow = leukemia

3. lens of the eye = cataracts

4. skin = skin cancer

Great Britain Loves Skins

Radiation can affect the growth and development of:

What does it impair?

fetus & young children

bone growth, mental abilities and more

The dose-response relationship curves for radiation protection purposes follow the (linear/non-linear) (threshold, non-threshold) model

linear, non-threshold (even tho organs have threshold doses), this is the most conservative model