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

Diamagnetism, In a non-uniform magnetic material, these substances move fro...

In a non-uniform magnetic material, these substances move from stronger parts of the field to the weaker parts.why?

Dc voltage measurements, DC voltage measurements: Examples of how to ma...

DC voltage measurements: Examples of how to make DC voltage measurements are show in the two diagrams below. In both cases, the red and black test leads are connected to the '

Calculate maximum range r, A tank is filled up to a height 2H by a liquid a...

A tank is filled up to a height 2H by a liquid and is placed on a platform of height H from the ground .the distance x from the ground where a small hole is punched to get maximum

Clamper, assignment of clamper

assignment of clamper

State gauss theorem in electrostatics, State Gauss' theorem in electrostati...

State Gauss' theorem in electrostatics. Using this theorem, derive the expression for the electric field intensity at any point outside a uniformly charged thin spherical shell.

Newton''s rings, why we take large radius of curvature of lens

why we take large radius of curvature of lens

How can time delay between the different modes be reduced, How can time del...

How can time delay between the different modes be reduced? The time delay between the various modes can be reduced when (a) the rays traveling off axis to the fiber are spee

Coulombs law, Coulomb's law (C. de Coulomb) The primary law for electr...

Coulomb's law (C. de Coulomb) The primary law for electrostatics is analogues to Newton's law of universal gravitation. This states that the force among two point charges is p

Scattering of light, Molecules of a medium after absorbing incoming light r...

Molecules of a medium after absorbing incoming light radiations, sends them in all direction. This process is called as Scattering.

Resolution of forces, Resolution of Forces: This topic is important, bu...

Resolution of Forces: This topic is important, but is really the opposite to Addition of forces. Recalling that two forces can be added to give a single force known

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