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

Explain beat period and beat frequency, Beat period : The time interval am...

Beat period : The time interval among two successive beats is called as beat period. Beat frequency : The number of beats given per second is called as beat frequency.

Physics Matlab Report, Hello, I have some computing physics coursework in...

Hello, I have some computing physics coursework involving Matlab. I would like to know if your organisation can get this coursework done for me. I am ready to upload the assignme

Explain electromagnetism, Electromagnetism: A temporary magnet formed b...

Electromagnetism: A temporary magnet formed by winding a coil of insulated copper wire around a piece of shift iron is known as electromagnet. When current is passed it behaves

Explain emitted photoelectrons, Light with a frequency of 7.5 x 10 14 Hz i...

Light with a frequency of 7.5 x 10 14 Hz is able to eject electrons from the metal surface of a photocell that has a threshold frequency of 5.2 x 10 14 Hz. What stopping potentia

Determine the phase angle between voltage and current, A coil havingof a re...

A coil havingof a resistance of 100 and an inductance of 200mH. If an alternating voltage, v, givenby v=200sin500t volts is applied across the coil, measure (a) The circuit

What are the alternatives to prevent tuberculosis, Alternatives to prevent ...

Alternatives to prevent tuberculosis - Another possible regimen for treatment of latent TB is daily rifampin alone for 4 months, which may be useful in persons intolerant to is

Big fish motion catches little fish-momentum and collision, Big Fish in Mot...

Big Fish in Motion Catches Little Fish Inelastic Collision: The animation below portrays the inelastic collision among a extremely massive fish and a less massive fish. Befor

Detection (receiver), Detection (Receiver): The antenna receiver these mod...

Detection (Receiver): The antenna receiver these modulated waves from different transmitting stations. Channel selector selects the desired signals. The selected signals are am

What is the child kinetic energy at the top of the swing, A 35-kg child is ...

A 35-kg child is riding on a swing that rises to a maximum height of 0.80 m. Neglecting friction, what is the child's gravitational potential energy at the top of the swing?

Describe reverberation time and absorption coefficient, Describe "Reverbera...

Describe "Reverberation time" and "Absorption coefficient". Illustrate Sabine's formula for reverberation time in a closed auditorium.

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