CLINICAL RADIATION GENERATORS

Question 1

Adequate dose cannot be delivered to a tumor beyond this depth

Answer 1

Orthovoltage
<2 cm

Question 2

In order for an adequate dose to be delivered to a tumor in DEEP THERAPY;

Answer 2

Increase beam filtration or HVL

Question 3

Disadvantages of Orthovoltage Therapy

Answer 3

Increase absorption in bone thus, making it unsuitable for treating tumors behind bone
Increase scattering
Depth dose distribution
Skin dose

Question 4

In the early days, treatments where given until..

Answer 4

skin becomes red or reached its radiation tolerance

Question 5

Limitation of Low energy beams/machines

Answer 5

Decrease depth dose distributions
Do not spare skin and normal tissue

Question 6

Advantages of Superficial Therapy

Answer 6

Limited penetration to underlying tissues
Rapid fall off

Question 7

KV Therapy Units/Machines

Answer 7

Grenz ray therapy
Contact therapy
Superficial therapy
Orthovoltage therapy
Supervoltage therapy

Question 8

water cooling system is for:

Answer 8

heat dissipation

Question 9

Requirements for Radiation Generators

Answer 9

High particle energy for penetration
High particle flux for sufficient dose rate
Energy efficient
Not too expensive
Reliable
Simple to operate
Safe

Question 10

Megavoltage Units/Machines

Answer 10

LINAC
COBALT 60
VAN DE GRAAFF
BETATRON
MICROTRON
CYCLOTRON

Question 11

electrostatic machine designed to accelerate charged particles

Answer 11

Van de graaff

Question 12

device that produces microwaves

Answer 12

Magnetron

Question 13

• high power oscillator
• generate microwave pulses for several microseconds
• with a repitition rate of several hundred pulses
• has cylindrical construction: central cathod, outer anode, and resonant cavities

Answer 13

Magnetron

Question 14

operate at 2 MV peak power output to power low energy LINACS (6 MV/less)

Answer 14

Magnetron

Question 15

T/F
electrons emitted from the cathode are accelerated TOWARD the anode by the action of pulsed DC electric field

Answer 15

T

Question 16

not a generator
microwave amplifier

Answer 16

klystron

Question 17

buncher cavity needs to be driven by a low power microwave oscillator

Answer 17

Klystron

Question 18

velocity of electrons is altered by

Answer 18

action of electric field known as velocity modulation

Question 19

series of discs

Answer 19

irises

Question 20

Advantage of Microtron to LINAC

Answer 20

simplicity
easy energy selection
small beam energy spread
smaller machine

Question 21

electrons from the gun

Answer 21

velocity of 0.8 c

Question 22

Used to generate high energy protons and
heavy ions for therapy.
◾Used to accelerate deuterons to produce
neutrons.
◾Used for the production of radionuclide’s . i.e.
for PET

Answer 22

Medical application of cyclotron

Question 23

Low energy photons (4 - 8 MV)

Answer 23

external wedges
fixed flattening filter
isocentric mounting
single transmission ionization
symmetric jaws

Question 24

begin building a LINAC

Answer 24

Henry Kaplan & Edward Ginzton 1952

Question 25

Kaplan and Saul Rosenberg

Answer 25

begin trials using the LINAC with chemotherapy to treat Hodgkins disease

Question 26

1st use of cyberknife

Answer 26

1994

Question 27

High energy

Answer 27

Klystron

Question 28

Low energy

Answer 28

Magnetron

Question 29

uses changing field in operation

Answer 29

LINAC Betatron Cyclotron Microtron

Question 30

uses positive charge

Answer 30

Van de graaff Cyclotron

Question 31

applies thermionic emission

Answer 31

LINAC Microtron Betatron Grenz ray Contact therapy Superficial therapy Orthovoltage or deep therapy Supervoltage therapy

Question 32

Uses filter

Answer 32

LINAC Grenz ray Contact or Endocavitary therapy Superficial therapy Orthovoltage therapy Supervoltage therapy

Question 33

beam ha a continuous spectrum of:

Answer 33

Bremmstrahlung xrays

Question 34

the penetrating power is adjusted through :

Answer 34

beam hardening by filtration

Question 35

beam quality depends on

Answer 35

accelerating potential and voltage

Question 36

damage DNA directly :

Answer 36

electric & proton

Question 37

T/F oxygen is best radiosensitizer in radthera

Answer 37

T

Question 38

Disadvantage of Betatron

Answer 38

low dose limited field size needs large treatment room due to large size limited motion

Question 39

allow electrons to travel along the waveguide and focus the beam

Answer 39

small holes or irises between copper cells

Question 40

who invented cobalt 60 unit in the 1950s

Answer 40

Dr. Harold Johns

Question 41

radioactive cobalt 60 isotope was discovered by?

Answer 41

Glenn T. Seaborg

Question 42

cobalt 60 is produced by:

Answer 42

irradiating or neutron bombardment of a stable cobalt (59Co) in a nuclear reactor

Question 43

primary treatment for laryngeal cancer

Answer 43

cobalt 60

Question 44

components of cobalt60 machine

Answer 44

gantry machine console patient support radioactive source source housing

Question 45

cobalt60 source emits two photons per disintegration with energies of

Answer 45

1.33 MeV & 1.17 MeV

Question 46

half life of cobalt60

Answer 46

5.26 years

Question 47

uses applicators / cones for field concentration

Answer 47

Superficial therapy

Question 48

In supervoltage, the voltage was stepped up in an efficient manner because of:

Answer 48

Resonant transformer - generatws xrays from 300 to 2000 kV

Question 49

Megavoltage Therapy Units

Answer 49

Van de graaff Betatron Microtron LINAC Cyclotron Cobalt 60

Question 50

machine using isotopes

Answer 50

teletherapy cobalt60 cesium137

Question 51

low energy photons 4-8 MV

Answer 51

external wedges fixed flattening filter isocentric mounting single transmission ionization chamber symmetric jaws

Question 52

medium energy photons 10-15 MV & electrons

Answer 52

bent beam dual transmission ionization chamber electron cones flattening filter movable target

Question 53

high energy photons 18-25 MV & electrons

Answer 53

achromatic magnet automatic wedge selector dual photon energy dual scattering foils

Question 54

made to spread the beam to get a uniform electron fluence

Answer 54

scattering foil

Question 55

make the beam intensity uniform since LINAC ic strongly forward peaked

Answer 55

flattening filter

Question 56

for accelerating guide and RF generator

Answer 56

vacuum pumping system

Question 57

used for cooling the accelerating guide, target, RF

Answer 57

water cooling system

Question 58

for pneumatic movement of the target and other beam shaping components

Answer 58

air pressure system

Question 59

against leakage radiation

Answer 59

shielding