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

Transformers.., describe and explain the operation of a transformer

describe and explain the operation of a transformer

Defects of vision and their correction, Defects of vision and their correct...

Defects of vision and their correction There is a simple relationship between the focal length F ,the object distance P and the image distance Q of a thin lens fig(1).

Force, formulas about force in detail

formulas about force in detail

What is the magnitude of the electric field inside capacitor, Five volts ar...

Five volts are applied across the plates of a parallel plate capacitor. The distance of separation of the plates is .02 meters. What is the magnitude of the electric field inside t

Explain spring force (fspring), Explain Spring Force (Fspring) Force ex...

Explain Spring Force (Fspring) Force exerted by a compressed or stretched spring upon any object that attached to it. An object that compresses or stretches a spring is always

Retardation plate, what do you mean by retardation plates?explain their fun...

what do you mean by retardation plates?explain their functioning by taking an example of a quarter wave plate

Grounding a positively charged electroscope, Grounding a Positively Charged...

Grounding a Positively Charged Electroscope While the positively charged electroscope is touched and its charge becomes grounded or neutralized this is depicted within the anim

Evaluate intensity ratio, Two waves of equal frequency have amplitudes...

Two waves of equal frequency have amplitudes 2 units and 3 units respectively. When they superpose coherently the intensity of the resultant wave is I 1 . The intens

Hole passing by the centre of earth, What will happen when a ball is droppe...

What will happen when a ball is dropped in a hole passing by the centre of earth through out diametrically? Ans) The ball will implement simple harmonic motion centered at the ce

Construction & chemical action of cell, Construction & chemical action of C...

Construction & chemical action of Cell: In cells, an electrolyte separates two charge collecting materials called electrodes, to which external connections are made. The electr

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