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

What are wave fronts, What are wave fronts? (Physics) A wave front is a...

What are wave fronts? (Physics) A wave front is an imaginary surface joining all points in space that are reached at the similar instant by a wave propagating by a medium. L

Filter, what is resistor filter?

what is resistor filter?

How many significant digits in 100m, How many significant digits are there ...

How many significant digits are there in each of the following measurements? a. 100 m 1 b. 0.0023 m/s 2 c. 100.1 m 4 d. 2.0023 5

Damped simple harmonic motion, Damped Simple Harmonic Motion Adding a d...

Damped Simple Harmonic Motion Adding a damping force proportional to x to the equation of easy harmonic motion, the first derivative of x along with respect to time, the equati

Evaluate tha power consumption bulb in series, Two students, A and B, livin...

Two students, A and B, living in neighbouring college rooms, decided to economise by connecting their ceiling lights in series. They agreed that each would install a 100-W bulb

Which of the two objects will start to slide first, Two objects are placed ...

Two objects are placed on a flat turntable at 10.0 cm and 20.0 cm from the center, respectively. The coefficient of static friction with the turntable is 0.50. The turntable's

Define sound waves, The energy to which the human ears are sensitive is nam...

The energy to which the human ears are sensitive is named as sound. In general all parts of waves are produced in an elastic material phase, Irrespective of while these are listen

Magnetic field is zero, Two parallel wires P and Q situated at a separation...

Two parallel wires P and Q situated at a separation of 6 cm carry electric currents i 1 =5 A and i2 = 2 A in opposite directions as given in fig-. Determine the point on the line

Radioactivity-bone cancer, Bone cancer -  A portion of the skeleton being ...

Bone cancer -  A portion of the skeleton being destroyed by cancer will be trying to rebuild itself and will take up more or many elements than normal bone. - The blood is injecte

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