Radiation therapy-megavoltage therapy, Physics

Assignment Help:

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.



Related Discussions:- Radiation therapy-megavoltage therapy

Curie weiss law for ferromagnetism, The first question one might ask about ...

The first question one might ask about ferromagnetic material is the source of the large magnetism. The saturation magnetization is so large virtually all the magnetic dipoles in t

Explain alternating current, Alternating Current: (AC) Such a current c...

Alternating Current: (AC) Such a current can be obtained if a resistor is linked in series with a source of alternating voltage. This current alters its direction so many times

Explain time of flight, TIME OF FLIGHT: "It is the total time for which...

TIME OF FLIGHT: "It is the total time for which the projectile remains in air". As, the body goes up and comes back to similar level, so it does not cover vertical distance,

Explain radius of gyration, Radius of gyration may be explained as the dist...

Radius of gyration may be explained as the distance from the axis at which, if the entire mass of the object were to be concentrated, the moment of inertia would be the same about

Presbyopia, Presbyopia: The accommodation power of a person is lost by ...

Presbyopia: The accommodation power of a person is lost by which the suffers a long sightedness. It is known as Presbyopia or lack of accommodation.

Scintillator counter, Ask question #Minimum 10theory0 words accepted#

Ask question #Minimum 10theory0 words accepted#

Fire accident in an industry?, If there is a fire accident in an industry, ...

If there is a fire accident in an industry, what  a safety enginner  will do? Ans) Normal 0 false false false EN-IN X-NONE X-NONE

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd