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

Maxwells electromagnetic equation, Starting from Maxwell's electromagnetic ...

Starting from Maxwell's electromagnetic equation in free space, Get Poynting theorem.

Describe q-factor in oscillation, Describe Q-factor in oscillations? How do...

Describe Q-factor in oscillations? How does it relay on damping

Strong anthropic principle, A more forceful argument which the weak princip...

A more forceful argument which the weak principle: This implies that if the laws of the Universe were not favorable to the development of intelligent creatures to ask regarding the

Concept of wave front , Concept of wave front  The basis of Huygens ...

Concept of wave front  The basis of Huygens wave theory of light is his principle concerning construction of wave front. When a disturbance from a light source travels i

Ratio of specific charge of a proton and an alfa-particle, The ratio of sp...

The ratio of specific charge of a proton and an  alfa-particle is: (1) 2 : 1 (2) 1 : 2 (3) 1 : 4 (4) 1 : 1 Ans:(1) 2 : 1

Wha is commutator, Commutator: The commutator is a form of rotating swi...

Commutator: The commutator is a form of rotating switch placed among the armature and external circuit and so arranged that it will reverse the link with the external circuit a

What is the dimentional formula of latent heat?, Hf = mLf m - (g/lbs) *1lb...

Hf = mLf m - (g/lbs) *1lb = 454g Lf - latent heat of fusion - 80 kcal/kg fr water Hope

Astrophysics, what will happen if we place a glass with the size of the ear...

what will happen if we place a glass with the size of the earth at a distance of 10 light years apart

YDSE, Consider Young’s double slit experiment with a finite ...

Consider Young’s double slit experiment with a finite sized ( height 2b) source whose center point is symmetrically oriented about the mid

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