Radiation Therapy

Question 1

What is an alpha particle?

Answer 1

Positively (+) charges electron
Two protons and two neutrons

Question 2

What is a beta particle?

Answer 2

Negatively (-) charged electron

Question 3

What is the penetrance of a negatively charged electron/beta particle?

Answer 3

None, it is stopped by a few sheets of aluminum or a few mm of tissue

Question 4

Which penetrates further, alpha or beta particles?

Answer 4

Beta

Question 5

What is a gamma particle?

Answer 5

Originates within the nucleus

Question 6

Where do x-rays originate?

Answer 6

Outside the nucleus

Question 7

What is an x-ray?

Answer 7

Electron-beams used most commonly to produce photon beams by bombarding material (tungsten) with high-energy accelerated electrons

Question 8

What is a proton?

Answer 8

Large positively (+) charged, created by acceleration at 300 mEV energies

Question 9

What is a neutron?

Answer 9

A large neutrally charged particle, MADE by accelerating a charged particle against a suitable substance or by fission

Question 10

What is a pi meson?

Answer 10

Negative pi mesons appear particularly suited for radiation therapy as their penetration and depth-dose profile lend themselves to shaping the high dose area to the tumor size and location

I.E. nuclear glue to hold up neutrons and protons in the nucleus

Question 11

What is the clinical application of the photoelectric effect?

Answer 11

Diagnostic radiology

Question 12

Is the photoelectric effect dependent on atomic number?

Answer 12

Yes, Z^3

Question 13

What is pair production?

Answer 13

A radiologic phenomenon that starts to occur at 1.02 mEV and continues to 30 mEV

Question 14

Is pair production dependent on atomic number?

Answer 14

Yes

Question 15

What is the clinical application of the Compton effect?

Answer 15

Radiotherapy

Question 16

What particle in the Compton effect interacts with DNA directly and H2O to form hydroxyl free radicals?

Answer 16

Displaced electrons

Question 17

What is the energy associated with the Compton effect?

Answer 17

2, but usually 6-20 MeV

Question 18

In the Compton effect, what does the incident photon interact with?

Answer 18

Loosely bound outer orbital electron

Question 19

In the Compton effect, what is the direct action?

Indirect action?

Answer 19

Direct: DNA Interaction

Indirect: formation of free hydroxyl radicals

Question 20

In the Compton effect, is absorption dependent on tissue density or number?

Answer 20

No

Question 21

What are the most common sources of brachytherapy in Gyn cancers?

Answer 21

Cesium 137 (30 yrs)
Iridium 192 (74 days)

Question 22

What type of energy is produced by bombarding material with highly accelerated electrons?

Answer 22

X-rays

Question 23

What is the origin of gamma rays?

Answer 23

Originates within the nucleus and are emitted from radioisotope decay

Question 24

What is linear energy transfer?

Answer 24

Rate of energy deposition along the path of the beam

Question 25

What has high LET?

Answer 25

Densely ionizing radiation like neutrons, alpha particles, pi-mesons

Question 26

What has low LET?

Answer 26

Sparsely ionizing radiation like gamma rays and high energy electrons (x-rays)

Question 27

What are the benefits of high LET energy?

Answer 27

More effective for NECROTIC tumors (hypoxic)

Question 28

What has the highest LET?

Answer 28

Neutrons

Question 29

What has the lowest LET?

Answer 29

250 kv x-ray