1 Radiation Therapy

Question 1

Sulfhydryl components

Answer 1

scavenge free radicals

Question 2

Administering a dose in fractions with adequate time between applications allows

Answer 2

the repair of sublethal damage

and the repopulation of tissue cells.

Question 3

Tumors often have poorly developed

Answer 3

blood vessels intermittent blood flow

Question 4

Dose range for solid tumor cure

Answer 4

60 to 80 Gy,

Question 5

Preventive (adjuvant) doses

Answer 5

45–60 Gy in 1.8–2 Gy fractions (for breast, head, and neck cancers.)

Question 6

In North America, Australia, and Europe, the typical fractionation schedule

Answer 6

for adults is 1.8 to 2 Gy per day, five days a week, For children, a typical fraction size may be 1.5 to 1.8 Gy per day

Question 7

External beam radiation therapy fails

Answer 7

to eradicate the primary tumor in 1 out of 3 patients

Question 8

E of protons used in proton therapy

Answer 8

190MeV with range 25cm (Bragg-Peak)

Question 9

the most common form of radiotherapy

Answer 9

External beam radiotherapy or teletherapy

Question 10

Kilovoltage (“superficial”) X-rays

Answer 10

treating skin cancer and

superficial structures. 50 to 200 kV

Question 11

Megavoltage (“deep”) X-rays

Answer 11

treat deep-seated tumors
(e.g. bladder, bowel, prostate, lung, or brain). 1 to 25 MV. Most common in therapy and produced in linac and Co units (Co-60 teletherapy machine)

Question 12

diagnostic X-rays

Answer 12

20 to 150 kV

Question 13

orthovoltage X-rays

Answer 13

200 to 500 kV

Question 14

supervoltage X-rays

Answer 14

500 to 1000 kV

Question 15

Intensity Modulated Radiation Therapy

Answer 15

intensity modulation is achieved by moving the leaves in the MLC(Multi-Leaf Collimator) during the course of treatment, thereby delivering a radiation field with a non-uniform (i.e. modulated) intensity in beamlets

Question 16

3D Conformal Radiation Therapy

Answer 16

utilizes sophisticated computer technologies such as CT scans and MRI images to view tumors in three dimensions (3D)-width, height and depth. With superior tumor imaging, patient treatment plans can be created with greater precision.

Question 17

Neutron Capture Therapy

Answer 17

the patient is injected with a tumor localizing drug containing a non-radioactive isotope that has a high cross section for slow neutron capture.;patient is radiated with epithermal neutrons, which after losing energy as they penetrate tissue, are
absorbed by the injected isotope, which then emits high-energy charged particles that deposit their kinetic energy locally,
thereby resulting in the killing of cancer cells.

Question 18

Isotopes Used in Neutron Capture Therapy

Answer 18

boron-10 only - BNCT

Question 19

The BNCT Reaction

Answer 19

10B+n=7Li+4He+Gamma (0.477 MEv)

Question 20

B agents used clinically

Answer 20

Sodium borocaptate (BSH); Boronophenylalanine (BPA)

Question 21

BNCT Dose Components

Answer 21

1H(n,gamma)2H, 14N(n,p)14C; fast neutrons from recoil. D=CFD(boron)+RBE(N)D(N)+RBE(R)D(R)+RBE(gamma)D(gamma)

Question 22

Brachytherapy or Endocurietherapy

Answer 22

Implanting radioactive sources into or close to tumor 50-70 Gy in 5-9
days is common

Question 23

common for temporary implants in Interstitial therapy

Answer 23

Iridium-192

Question 24

iodine- 125 in Interstitial therapy

Answer 24

common for permanent implants total prescribed dose of 160 Gy, with 80 Gy delivered in the first 60 days.most effective in slow-growing tumors

Question 25

Radio-Immuno Therapy

Answer 25

administration of a radionuclide conjugated

to a monoclonal antibody for therapeutic intent

Question 26

Radioimmunotherapy Limitations

Answer 26

Bone marrow toxicity, poor tumor penetration, poor tumor antigen/receptor expression: Iodine-131, alpha emitters: Ac-225(7MEV alpha, milked from 229 Th cow), Th-227 (6MEV alpha), U-230, At-211

Question 27

cancer Societal Cost

Answer 27

106b

Question 28

cancer survival rate

Answer 28

40%

Question 29

Radiograph- x-ray

Answer 29

Intensity of diagnostic x-rays (10 - 150

keV) attenuated in body

Question 30

Computed Tomography

Answer 30

Spatial distribution of attenuation coefficients in body

Question 31

Magnetic Resonance Imaging:

Answer 31

Spatial distribution of proton density in body

Question 32

CT or CAT Scan

Answer 32

shows organs of interest at selected levels
of the body. They are visual equivalent of bloodless slices of anatomy, with each scan being a single slice. source of the x-ray beam encircles or rotate around the patient. X-rays passing through the body are
detected by an array of detectors. Information from the detectors is computer processed and then displayed as an image on a video screen.

Question 33

CT vs MRI

Answer 33

MRI has no radiation, and good for soft tissue difference recognition. A longer time than CT and more expensive.

Question 34

Technetium-99m

Answer 34

half life of 6 hours, gamma emitter from Mo cow. Scan is done 2-3 h after injection, takes about 30 min

Question 35

SPECT

Answer 35

uses radioactive tracers and scanner can give information about blood flow to tissues and chemical reactions (metabolism) in the body. Antibodies can be labeled with radioactive tracers and attach to a tumor.

Question 36

Positron Annihilation

Answer 36

β+ + β-=2γ with E= 2*0.511 MEv

Question 37

PET tracer for Cerebral blood flow

Answer 37

Positron emission tomography. 15O in water tracer

Question 38

FDG

Answer 38

Most used PET tracer. Tracer for 18F for glucose metabolism. Taken up by tumors.

Question 39

CT and SPECT

Answer 39

CT gives an image of an anatomical structure while SPECT gives info about the metabolism and functions of organs.

Question 40

SPECT

Answer 40

Single-photon emission computed tomography

Question 41

Dual-Modality Imaging

Answer 41

Structural Imaging (CT, MRI) + Functional Imaging (SPECT, PET)