Methods Of Radthera Flashcards
• radiation therapy technique for which the source of radiation is at some distance from the patien
TELETHERAPY (EXTERNAL BEAM RADIATION THERAPY)
6 Classification of EBRT Machines: GCSOSM
Grenz Ray Therapy
Contact Therapy or Endocavitary
Superficial Therapy Units
Orthovoltage Therapy or Deep Therapy Unit
Supervoltage Therapy Unit
Megavoltage Therapy Unit
therapy applies to treatment with xrays produced at potential ranging from 50 to 150 kV. The
maximum absorbed dose or energy deposited in a mass of tissue occupying a small volume is produced on the
surface with rapid fall off of dose with increasing depth.
SUPERFICIAL THERAPY UNITS
This equipment produces a large amount of soft (low
energy) x-rays which can produce severe skin reaction
thus, it is useful for irradiating tumors to about 5mm depth.
Superficial Therapy unit
SUPERFICIAL THERAPY UNIT (SSD) typically ranges from __ to___ The machine is usually operated at the tube
current of __ to __ mA
15 to 20 cm.
5 to 8 mA
▪ X-ray beams of energy 1 MV or greater can be classified
as megavoltage beams. Although the term strictly applies
to x- ray beams, the gamma ray beams produced by
radionuclides are also commonly included in the category if their energy is 1 MeV or greater.
Megavoltage Therapy Unit
▪ X-ray therapy in the range of 500 to 1,000 kV has been
designated as high-voltage therapy or __ In the quest for higher energy x-ray beam, considerable progress was made after World War II toward developing the high voltage machines.
▪ Since the electron attain high energies before striking the target, a transmission type target may be used to obtain the x-ray beam on the other side of the target.
Supervoltage Therapy Unit
▪ A therapy machine operates at potentials of 40 to 50 kV and facilitates irradiation of accessible lesions at
very short source (focal spot) to the surface of the skin
Contact Therapy or Endocavitary
CONTACT THERAPY: (SSD of __) It operates with a tube current of __.
▪ To absorb low energy x-rays a __-__ mm aluminum
filter is utilized. This quality of radiation is useful for tumors not deeper than _ to _ mm and the beam is almost completely absorbed with 2 cm of soft tissue.
2cms.2 mA
0.5 - 1.0 mm
1-2
is used to describe treatment with x-rays produced at potentials ranging from 150-500 kV. Reasonable tissue penetration of the resultant x-ray beam is achieved with this equipment, which also must be operated with filters to reduce the soft x-rays
Orthovoltage Therapy or Deep Therapy Unit
SSD of orthovoltage
50cm
▪ X-ray therapy in the range of 500 to 1,000 kV has been designated as high-voltage therapy or supervoltage therapy. In the quest for higher energy x-ray beam, considerable progress was made after World War II toward
developing the high voltage machines.
▪ Since the electron attain high energies before striking the
target, a transmission type target may be used to obtain
the x-ray beam on the other side of the target.
Supervoltage Therapy Unit
Grenz Ray therapy
<_ kV
Skin cancerr,very soft energy
20
Contact Therapy
__-__kV
SSD: __cm
__ mA tube current
__-__ mm ( tumors)
40-50
2
2
1-2
Superficial therapy unit
__-__ kV
__mm depth
SSD: __-__
__-__mA
50-150
5
15-20
5-8
