LASERs: UV Flashcards Preview

Medical Physics: Imaging w/ Non-Ionising Radiation > LASERs: UV > Flashcards

Flashcards in LASERs: UV Deck (17)
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1

What wavelength region of the electromagnetic spectrum is covered by UVA?

315-400nm

2

What wavelength region of the electromagnetic spectrum is covered by UVB?

280-315nm

3

What wavelength region of the electromagnetic spectrum is covered by UVC?

100-280nm

4

What are the components of a UV radiometer?

Diffuser
Filter
Detector
Amplifier
Display

5

What are the features of a Bare silicon detector?

+/-50% inherent variation in the 250-400nm band
UVA phototherapy-type filter
Shaped to accept 315-390nm only (UVA)
Calibration is source specific.

6

What are the features of a bare GaSP detector?

+/-50% inherent variation in the 250-400nm band
UVA phototherapy-type filter
Shaped to accept 290-340nm only (UVB/A)
Calibration is source specific.

7

What are some errors in spectro-radiometry?

Wavelength calibration
Correct Bandwidth
Effect of Stray radiation
Angular dependence of incoming photons.
Linearity of device
Use of Calibration source

8

How do you calibrate a narrow band detector?

Measure the spectral irradiance of the source of interest with a spectra-radiometer.
Integrate over the waveband of interest.
Place the narrow band detector in the same location as the spectra-radiographer.
Adjust eh meter so it reads correctly.

9

What is used for personal dosimetry when working with UV and what properties does it have that make it ideal?

Polysulfone film
- High-performance plastic sheet detects change in light transmission.
Response is proportional to dose, but independent of dose rate and temperature.
Action spectrum matches the bio-effect.

10

What are four effects that UV radiation has on the skin?

Sunburn
Skin Cancer
Skin Aging
Vitamin D Production

11

How far can UVA penetrate into the eye?

Can reach the retina.

12

How far can UVB penetrate into the eye?

Stopped by the cornea.

13

What is an acute effect of UV radiation on the eye?

Photokeratitis (Snow Blindness)

14

What is a chronic effect of UV radiation on the eye?

Cataracts.

15

What is the Maximum Permissible Exposure for the eyes and skin from UV radiation?

30J/m^2 (180-400nm)

16

What is the Maximum Permissible Exposure for the eye from UV radiation?

10,000J/m^2 (315-400nm)

17

Over what time frame is the Maximum Permissible exposure calculated?

Over an 8hour working day.