Advanced VIS-IR Techniques for Diagnosis

Question 1

What is the spectral range of visible light?

Answer 1

390-780nm.

Question 2

What is the spectral range of IR-A (near IR)?

Answer 2

760-1,400nm.

Question 3

What is the spectral range of IR-B?

Answer 3

1,400-3,000nm.

Question 4

What is the spectral range of IR-C?

Answer 4

1,400nm-1mm.

Question 5

Name and describe the cause of the four interactions between light and tissue.

Answer 5

Reflection - Sudden change in refractive index between air and tissue.
Absorption - Pigmentation in tissue.
Scattering - Caused by micro-structures of the tissue.
Fluorescence - Light of one wavelength absorbed and re-emitted as a different longer one.

Question 6

What adverse biological events occur with VIS-IR light?

Answer 6

• Photosensitivity - due to chemicals.
• Photothermal - heating and vaporisation.
• Photomechanical - Shockwaves (by LASER).
• Photochemical - Triggering of chemical reactions.

Question 7

How is peripheral arterial disease (PAD) diagnosed using photoplethysmography (PPG)?

Answer 7

• PPG measure pulsatile blood flow in extremities by measure difference in absorption over time.
• Timing delay between peak flow visible in opposing extremities in PAD patients.
• Shape damping in affected limb.

Question 8

Name some condition Thermal Imaging is used to assess.

Answer 8

• Raynaud’s.
• Inflammation Assessment.
• Mitochnodrial Disease (MERRF).
• Erythromelagia.
• Complex Regional Pain Syndrome.
• FREY SYndrome.
• Renal Fistula Assessment.

Question 9

What is LASER Doppler Imaging used to assess?

Answer 9

Microvascular blood flow.

• Burn depth.
• Thermal hyperaemia.
• Iontophoresis.
• Endothelial function.

Question 10

What is LASER Speckle used in the assessment of?

Answer 10

• Thyroid eye disease.

- Tissue viability.