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

Derive lorentz transformation equations, (a) State the postulate of STR and...

(a) State the postulate of STR and deduce Lorentz Transformation. OR Give basic postulate of special theory of relativity. Derive Lorentz Transformation equations. (b) Pro

Release of energy by the process of nuclear fusion, Draw a graph showing th...

Draw a graph showing the variation of binding energy per nucleon with mass number for dissimilar nuclei. Describe, with the help of this graph, the release of energy by the process

Simple cubic and body centred cubic, Normal 0 false false f...

Normal 0 false false false EN-IN X-NONE X-NONE

What is the true weight of the satellite, A satellite has a mass of 5900 kg...

A satellite has a mass of 5900 kg and is in a circular orbit 3.0 x 10 5  m above the surface of a planet. The period of the orbit is two hours. The radius of the planet is 4.15 x 1

Determine watts of power dissipated for potential difference, The constant ...

The constant potential difference across a 2 ohm resistor is 20 volts. How many watts of power are dissipated by this resistor? Ans: 200 watts of power are dissipated throug

Mauls law, Description about mauls law

Description about mauls law

Describe the type of analysis , Suppose that a colleague comes to you for h...

Suppose that a colleague comes to you for help prior to conducting an experiment with two treatments to determine the effects on the density (weight) of cornbread.  The recipe for

Stefan-boltzmann constant, Stefan-Boltzmann constant; sigma (Stefan, L. Bol...

Stefan-Boltzmann constant; sigma (Stefan, L. Boltzmann) The constant of proportionality exist in the Stefan-Boltzmann law. It is equivalent to 5.6697 x 10 -8 W/m 2 /K 4 .

Explain electric flux, Explain electric flux. Write its S.I. units. A spher...

Explain electric flux. Write its S.I. units. A spherical rubber balloon carries a charge that is uniformly distributed over its surface. As the balloon is blown up and enhances in

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