d8

Question 1

Alpha, beta, gamma, proton, neutron and positron emissions are used for

Answer 1

medical treatment.

Question 1

Alpha particles

Answer 1

nuclei of helium-4.

Question 2

draw symbol for alpha particles

Question 3

Beta particles

Answer 3

high energy electrons emitted from atomic nuclei

Question 4

draw symbol for beta particles

Question 5

Gamma rays

Answer 5

photons with very short wavelengths

Question 6

draw symbol for gamma rays

Question 7

Positrons

Answer 7

positively charged electrons

Question 8

what is Magnetic resonance imaging (MRI)

Answer 8

an application of NMR (nuclear magnetic resonance) technology

Question 9

describe MRI scanners

Answer 9

use superconductive magnets to create powerful magnetic fields and also produce radio waves.

Question 10

describes how MRI works

Answer 10

1. When a patient is placed inside the magnet, the protons in the body constantly change their states, absorbing and emitting radio waves of a certain frequency, which are then detected by the scanner and processed on a computer.
2. The protons in water, lipids, carbs and proteins have different chemical environments which can easily be distinguished by 1H NMR chemical shifts. The concentrations of these compounds in various tissues are different, so MRI provides detailed images.

Question 11

pros of MRI scanners

Answer 11

No ionising radiation so can be used repeatedly without increasing the risk of cancer to the patient

Question 12

cons of MRI scanners

Answer 12

• High cost of equipment
• Interaction of magnetic fields with metal body implants

Question 13

use of radiotherapy

Answer 13

used to treat cancer.

Question 14

two types of radiotherapy

Answer 14

internal (brachytherapy)
external

Question 15

internal radiotherapy

Answer 15

Radiation sources are inserted into the patient’s body in the form of metal wires or pellets that deliver radiation directly to the site of the disease.

Question 16

External radiotherapy

Answer 16

Involves precisely directed beams of gamma rays, protons, electrons or neutrons.

Question 17

why are cancer cells are more likely to die from radiation exposure than normal cells?

Answer 17

• their accumulation of DNA errors, which eventually limits their ability to grow and multiply
• their reduced ability to repair their genetic material.

Question 18

give and explain the common side effects of radiotherapy

Answer 18

Common side effects of radiotherapy: hair loss, nausea, fatigue and sterility. A long term risk of radiotherapy is the development of secondary cancers.
Normal dividing cells are also sensitive to induced DNA errors by ionising radiation.

Question 19

what are Targeted Alpha Therapy (TAT) and Boron Neutron Capture Therapy (BNCT)

Answer 19

two methods which are used in cancer treatment.

Question 20

TAT:

Answer 20

• controlled amounts of alpha emitters can be delivered by a carrier drug or protein directly to the targeted cancer cells, which will be selectively destroyed by radiation without significant damage to the surrounding tissues.
• at the same time, collisions of alpha and beta particles with atomic nuclei produce secondary gamma radiation, which can be detected and used to map the distribution of cancer cells in the body.

Question 21

BNCT:

Answer 21

High intensity neutron beams are used, taking advantage of the ability of boron-10 to absorb neutrons and transform into boron-11, which immediately undergoes alpha decay.
[WRITE EQUATION]
Both lithium-7 ions and alpha particles cause extensive cellular damage in a very limited range. Therefore tumours can be destroyed if they accumulate sufficient boron-10, which can be administered by intravenous injection of certain organoboron compounds.

Question 22

Explain why Technetium-99m is the most common radioisotope used in nuclear medicine based on its emission type

Answer 22

Emission type/chemistry:
- nucleus is metastable- can only exist for a short period of time
- nucleus returns to a lower energy state by emitting electromagnetic radiation:
[WRITE EQUATION]
- photons produced by t-99m have approximately the same wavelength as x-rays so can be detected using traditional x-ray material.
- energy of the photons is relatively low so reduces the radiation dose received by the patient and medical personnel.

Question 23

Explain why Technetium-99m is the most common radioisotope used in nuclear medicine based on its chemistry

Answer 23

T-99m has various oxidation states (+3, +4, +7) and readily forms complexes with various ligands, which can be administered by injection and delivered to target organs/tissues.

Question 24

Explain why Technetium-99m is the most common radioisotope used in nuclear medicine based on its half life

Answer 24

6 hours, making it ideal for medical imaging
After the gamma scan is complete nearly all the injected radionuclide decays within two days, minimising the patient’s exposure to radiation
Long enough to prepare various complexes of this radionuclide with biologically active ligands

Question 25

define half-life

Answer 25

the time required for half of the initial amount of radionuclide to decay

Question 26

two similarities between Lutetium-117 + Yttrium-90

Answer 26

Pure beta emitters used in radiotherapy
Nuclides decay in one step and produce stable isotopes:
insert equation

Question 27

Yttrium-90 is used as

Answer 27

a common radiation source for cancer brachytherapy + palliative treatment of arthritis.

Question 28

why is Lutetium-177 useful?

Answer 28

• produces low-energy beta particles with reduced tissue penetration, which is very useful in the targeted therapy of small tumours.
• emits just enough gamma rays for visualising tumours and monitoring the progress of their treatment.