Radiation therapy-megavoltage therapy, Physics

Megavoltage  therapy:

Kerst developed the betatron  which accelerates electrons to high energy .It open a new radiation therapy era-the supervoltage or  megavoltage era.Another development in the radiation therapy is the application of man made  radioactive  source .

One of the radioactive sources:


Cobalt 60:
it emits penetrating  gamma  rays of about 1.25 Mev energy.60Co units (also called cobalt teletherapy  and  cobalt  bomb units)


-The high energy gamma rays emitted by 60Co are absorbed by tissue and produce high energy electrons .
- Most of electrons  move in the same direction as  the original beam .
- As the gamma ray beam penetrates the first few mm beneath  the skin ,the no. of electrons increases and the energy deposited by them increases.
- The dose maximum  occurs  about 5 mm below the  skin .
-The relatively  low  dose at the skin from high energy x-rays of  gamma rays  is referred  to as the skin –sparing effect.
-The radiation from 60Co  teletherapy unit is emitted continuously ,the unit is turned on by rotating  the source wheel until the source is over the beam port in the  large lead shield .It is turn off by rotating the source wheel until the source  shielded by the wheel  fig (1).

 

2137_Radiation therapy-Megavoltage  therapy.png

Mega voltage therapy has three  major  advantages :

-    The maximum dose  occurs  below the skin and the skin sparing effect greatly reduces the pain from the treatment.
-    The high energy is almost completely in the Compton  effect region and doses not give a large doses to the bone .
-    The greater penetrating  ability permits better treatment of tumors deep inside the body.


Posted Date: 10/1/2012 7:50:05 AM | Location : United States







Related Discussions:- Radiation therapy-megavoltage therapy, Assignment Help, Ask Question on Radiation therapy-megavoltage therapy, Get Answer, Expert's Help, Radiation therapy-megavoltage therapy Discussions

Write discussion on Radiation therapy-megavoltage therapy
Your posts are moderated
Related Questions
Explain  vectors Vectors : a quantity that has a size as well as direction is known a vector. So, for example, the wind blows with some speed and in some direction. So the win

Bohr given a model for hydrogen molecule which is also applicable for some lighter atoms in which a one electron revolves around a stationary nucleus of positive charge Ze (known a

A monkey of mass m climbs a rope slung over a light frictionless pulley.The opposite end of the rope is tied to a block of Mass M lying on a smooth horizontal plane.Find the accele

Discusse about motion of satellite

as flux = E.A and flux density is equal to flux/A then why A/A cannot e cancelled ?

Surface crystallography and epitaxy. Fe thin films are grown on a single-crystal Al(100) substrate surface. The films grow with no dislocations (if they are thin enough) with sug


Permeability of free space; magnetic constant; mu_0 The ratio of the magnetic flux density in a substance is to the external field strength for vacuum. This is equal to 4 pi x

Explain Generation of electrical energy Generation of electrical energy : The conversion of energy available in dissimilar forms  in nature into electrical energy is called as

create and sketch an equipment to conserve energy