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Physics of light in medicine

الكلية كلية طب حمورابي     القسم الكلية ذات القسم الواحد     المرحلة 1
أستاذ المادة نادية حسين صاحب طاهر       07/12/2018 14:00:59

Physics of light in medicine

Objectives
1- Definition.
2-Knowledge of the physical properties of light.
3-To get information about applications of light in medicine.
4- To get information about the principle of using laser in medicine.

Definition
 Light is a form of electromagnetic radiation.
Human eye has the capability to detect or sense some part of the complete electromagnetic spectrum.


Properties of Light

1- The speed of light when it goes from one material into another given by equation:
n= c / v
c: Speed of light in vacuum
v: Speed of light in material
n: Refractive index

When light is absorbed, its energy generally appears as heat.
This property is the basis for the use IR
light to heat tissues.

Also the heat produced by laser beams is used to weld and to coagulate small blood vessels.

Some time when a light photon is absorbed,
a lower energy light photon is emitted.
This property is known as fluorescence


2. Light is reflected to some extent from all surfaces.

There are two types of reflection:

A- Diffuse reflection: occurs when rough surface scatter the light in many direction.

B- Specular reflection: it is obtained from very smooth surface such as mirrors.

3. Refraction: When light passes through a substance or medium, light gets bend on the basis of the wavelength or frequency. This phenomenon is termed as the refraction. It follows Snell’s Law of refraction.

4. Light transmittance is defined as the ratio of the intensity of the Incident light on the substance to the intensity of light which passes through the substance or comes out from the substance

Bronchoscope: Are used for examining the air passages into lungs. Some endoscopes are rigid tubes with a light source to illuminate the area of interest.

Flexible endoscopes can be used to obtain information from regions of the body that cannot be examined with rigid endoscopes, such as the small intestine and much of large intestine.

Laser in Medicine

Light Amplification by Stimulated Emission of Radiation
When an electron makes a transition from higher energy to lower energy state, a photon is emitted.
The emission process can be one of two types:
1-Spontaneous Emission.
2-Stimulated Emission.


المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .