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

Illustrate a labelled diagram of hertz experimental, Illustrate a labelled ...

Illustrate a labelled diagram of Hertz's experimental set-up to produce electromagnetic waves. Describe the generation of- electromagnetic waves using this set-up.

Thermo electric thermometer, #question.what isthe range of thermoelectric t...

#question.what isthe range of thermoelectric thermometer?.

Is low attenuation is a sign of good quality fibers, Is low attenuation is ...

Is low attenuation is a sign of good quality fibers? Usually yes low attenuation is a sign of good quality fibers, but within lighting fiber optics the manufacturer's attenua

ASSIGNMENT, VRIFY THE CURRENT DIVIDER RELATION AND VOLTAGES DIVIDER RELATIO...

VRIFY THE CURRENT DIVIDER RELATION AND VOLTAGES DIVIDER RELATION

Density of energy state, Q. What is the density of energy states in metals?...

Q. What is the density of energy states in metals? Obtain an expression for the density of states for free electron gas in metals.   Ans.  Density of energy state is define

Describe the variation of the radius of bright fringe, Describe the variati...

Describe the variation of the radius of bright fringe of Newton's rings with refractive index of the thin film enclosed between the glass plate and plan-convex lens when observed b

Electrostatic shielding, 12 to 16 pages project or assignment on electrosta...

12 to 16 pages project or assignment on electrostatic shielding

What is the force required to accelerate a mass, What is the force required...

What is the force required to accelerate a mass of one kilogram one meter per second per second? Basically, you have defined the Newton. Force is the vector product of mass

Why x-ray photon collides with a free electron, An x-ray photon collides wi...

An x-ray photon collides with a free electron, and the photon is scattered.  During this collision there is conservation of: a) momentum but not energy b) neither moment

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