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

Rotational equilibrium, A light horizontal bar has a length of 3m. If a 102...

A light horizontal bar has a length of 3m. If a 102-kg mass is placed 80 cm away from the left end of the bar and a 109-kg mass is placed 2.15 m from the left end, where must it be

What is meant by the term modulation, What is meant by the term 'modulation...

What is meant by the term 'modulation'? Define with the help of a block diagram, how the process of modulation is carried out in radio broadcasts.

Measurement of the thickness of a thin transparent mica slit, Q.   Describe...

Q.   Describe the method of measurement of the thickness of a thin transparent mica slit using Fresnel's Bi-prism. Give necessary theory. Draw suitable diagram. Measurement of

Magnetism, explain origin of dimagnetsm on the basis of its atomic structur...

explain origin of dimagnetsm on the basis of its atomic structure

Motion, motion mean laws of motion explain explian motion lesson

motion mean laws of motion explain explian motion lesson

Discuss about the term graded index fibre, Discuss about the term graded in...

Discuss about the term graded index fibre. Graded index fibre: A graded index fibre is diverse from the step index fibre not merely in the core refractive index variation bu

Constant negative velocity, Constant Negative Velocity Observe in which...

Constant Negative Velocity Observe in which the object below moves along with a constant velocity within the negative direction. The dot diagram displays in which each consecut

Light and sound, Does a piece of glass reflect more light than a piece of p...

Does a piece of glass reflect more light than a piece of paper?

Evaluate the current in given example, Q. If a dog rolled around on a carpe...

Q. If a dog rolled around on a carpet as well as gets statically and a flea jumps on it will the flea get electrocuted? Answer:- It will but possibly not and such experime

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