D.8: NUCLEAR MEDICINE (AHL)
UNDERSTANDINGS
- Alpha, beta, gamma, proton, neutron, and positron emissions are used for medical treatment.
- Magnetic resonance imaging (MRI) is an application of NMR technology.
- Radiotherapy can be internal and/or external.
- Targeted Alpha Therapy (TAT) and Boron Neutron Capture Therapy (BNCT) are two methods which are used in cancer
treatment.
APPLICATION AND SKILLS
- Discussion of common side effects of radiotherapy.
- Explanation of why technetium-99m is the most common radioisotope used in nuclear medicine based on its half-life, emission
type, and chemistry.
- Explanation of why lutetium-177 and yttrium-90 are common isotopes used for radiotherapy based on the type of radiation
emitted.
- Balancing nuclear equations involving alpha and beta particles.
- Calculating the percentage and amount of radioactive material decayed and remaining after a certain period of time using the
nuclear half-life equation.
- Explanation of TAT and how it might be used to treat diseases that have spread throughout the body.
NATURE OF SCIENCE
- Risks and benefits – it is important to try and balance the risk of exposure to radiation with the benefit of the technique being
considered.
INTRO: WHAT IS RADIOACTIVITY?
-Usually we speak of chemical reactivity in terms of changes to the distribution of ________________ in atoms. Nuclear
chemistry involves the changes and emissions that result from the transition of unstable atomic _________________into
more stable forms.
-Radioactivity involves the spontaneous emission of _______________ and ______________ from the _______________
as an atom decays into a more ______________ form. The emissions are known as ________________.
-_______________ atomic nuclei emit ____________________.
 STABLE NUCLEUS
UNSTABLE NUCLEUS 
(RADIONUCLIDE)
RADIATION: emission of particles and energy
-Radioactivity is known as _____________________radiation, because it has enough energy to interact with an atom and
cause the removal of ________________.
*(radiation = ionizing = removal of e- from __________ shells = free ____________ = damage to _____ = __________)
TYPES OF RADIATION:
A. SUMMARY
Common Name Particle
*Alpha particle
Helium-4 nucleus
*Beta particle
Positron emission
Proton beam
Electron
Positron
Proton
Symbol
α ; 24 He
β- ; eβ+; e+
p ; 11 p ;
1
1
Neutron beam
Neutron
Charge, e*
+2
Mass, u**
4.0
-1
+1
+1
0.0005
0.0005
1.0
Common Sources
Particle accelerators
H
0
1.0
n ; 01 n
Gamma ray
Photon
γ
0
0
X-ray***
Photon
0
0
*1 e = 1.6 x 10-19 C ; **1 u = 1.7 x 10-27 kg; ***not emitted by radionuclides
Bombardment of
X-ray tubes
B. THE THREE MAIN TYPES OF RADIATION
RADIATION TYPE
DESCRIPTION
- ejection of _____________ particles from the ___________
ALPHA
- alpha particle = ___________ nucleus ( 24 He or 24 )
- helium nucleus = __ p+ and __ n0
BETA
GAMMA
- ejection of ___________ particles from the _____________
- beta particle = _________________ ( 10  )
- formed during the conversion of ______________ to
______________
- emission of very _________ energy gamma (γ)
_______________
- results from energy changes in the nucleus and does not alter
the _____________ or _____________ numbers
- often accompanied by alpha or beta ejection
EXAMPLE
238
92
U
234
90
Th 
11
5
B 
PRACTICE: Balancing Nuclear Equations Involving Alpha and Beta Particles:
1. Write nuclear equations for the following reactions, making reference to section 5 of the IB data booklet:
(a) the alpha decay of an isotope of radon that has mass number 219
(b) the beta decay of carbon-14
TERMS: NUCLEAR MEDICINE
TERM
NUCLEAR MEDICINE
DEFINITION
- uses ___________________ materials in the ___________________ and
___________________ of diseases (esp. cancer)
RADIONUCLIDE
(RADIOISOTOPE)
- unstable _________________ of certain elements that undergo spontaneous
____________________ decay and emit _________________ radiation;
administered in the form of water-soluble __________or ______________ that
are distributed around the body via _____________;
- *Radionuclides exist __________________ (e.g. 235U , 3 H , 40 K ) and all
elements with Z = 84 and higher can be produced ______________________
(most that are used in nuclear medicine are produced this way).
RADIOTHERAPY
- uses ___________________ radiation to treat ______________
INTERNAL RADIOTHERAPY
- radiation sources inserted into patient’s body in the form of metal _________ or
______________ that deliver radiation directly to the ________ of the disease
EXTERNAL RADIOTHERAPY
- cancerous cells destroyed by more powerful sources of ionizing radiation used
such as directed beams of gamma rays, protons, electrons, positrons (positively
charged electrons), or neutrons
RADIOPHARMACEUTICAL
- drugs containing a combination of a ___________________ and a
______________________ active compound (e.g. ____________, ___________)
- aim of drug is to deliver radionuclides to specific tissues or cellular receptors
NUCLEAR MEDICINE TECHNIQUES (EXAMPLES)
NUCLEAR MEDICINE
TYPE
1. CANCER _______________ NUCLEAR IMAGING
(EXTERNAL)
EXAMPLES
(a) Scintigram
DESCRIPTION
- _________ ray photograph generated
by nuclear emissions from the body
- used to detect _____________
(b) PET (Positron Emission
Tomography)
- gives 3D images of _______________
concentration in the body where it
accumulates in target tissue
- application of ________ technology
- produces images of internal body
organs and soft tissue
- identifies presence of tumours
(c) MRI (Magnetic Resonance
Imaging)
2. CANCER ________________
(INTERNAL)
*(a) Targeted Alpha Therapy (TAT)
**(b) Boron Neutron Capture Therapy
(BNCT)
- radioimmunotherapy (See details
below.)
- 105 B + 01 n  115 B  24 + 37 Li
(See details below.)
*TARGETED ALPHA THERAPY (TAT)
https://www.youtube.com/watch?v=YdEt6wjE1Lg (Ted talk)
TAT OVERVIEW / SUMMARY
- _________________ (i.e. _____________________/ secondary) cancers
USED TO CONTROL
- suitable for some pancreatic, ovarian and melanoma cancers
BENEFITS
- _________________ (i.e. targets cancer cells opposed to healthy cells)
- use of alpha emitter = very small ____________ = minimal irradiation of
______________ tissue surrounding the targeted cancer cells  much less than
___________ emitter, for example
TERM
ANTIGEN
DEFINITION / TAT CONNECTION
- any substance that causes an immune system to produce antibodies against it
- In this context, think of an antigen as a unique feature of the cancer cell that makes
it different from a _______________ cell.
ANTIBODY
- ‘Y’ – shaped proteins which function to identify and help remove foreign antigens
or targets such as viruses and bacteria
- In this context, think of the antibody as a protein attracted only to a specific
antigen…the one on the _______________ cell.
- antibody ‘___________’ on antigen and then ________ alpha particle thereby
___________________ cell
RADIOIMMUNOTHERAPY - uses ___________________ isotopes
- immunotherapy refers to the antibody/_______________ interaction
RADIOIMMUNOTHERAPY - contains _________________ and _____________ particle emitter (i.e.
radioisotope that emits alpha particles)
DRUG
208
4
-e.g. Lead-212 = alpha emitter that can be used: 212
82 Pb  2  + 80 Hg
PICTORIAL SUMMARY
**BORON NEUTRON CAPTURE THERAPY (BNCT)
- used to treat brain tumours and recurrent head and neck cancers
BNCT
(SUMMARY
REACTION)
10
5
STEP
DESCRIPTION
B + 01 n 

1
- patient injected with _______-radioactive, non-toxic/inert isotope of ____________ (B-___)
…which is ______________ absorbed by ___________ cells (in head an neck)
2
- patient irradiated with (non-toxic) _____________ which are ______________ by B-10 (this causes
a _______________ reaction)
3
- Radioactive/dangerous boron (B-____) is converted into an isotope of ___________ (Li-____)
- accompanying this conversion is an __________ particle emission which acts directly on tumour
(little damage to surrounding healthy cells…alpha particle only has a range of about ____ cell)
COMMONLY USED RADIOISOTOPES IN NUCLEAR MEDICINE
ISOTOPE
m
Tc )
*Technetium-99m ( 9943
‘m’ = metastable (exists for short
period)
*most commonly used
radioisotope in nuclear medicine
(over ______% if diagnostics rely
on this isotope)
ADVANTAGE
_______-life
EXPLANATION
- half-life = _____ hrs
- enough time for scanning __________________
- decays quickly enough to minimize _______________ exposure
______________
- _______ RADIATION DOSE - relatively low energy
______________ rays ( approx. same wavelength as ____-rays) 
escape body and detected by γ camera or traditional X-ray
equipment
99 m
43
Tc  99
43Tc + γ
- low energy electrons = low radiation dose
Lutetium-77 &
Yttrium-90
Versatile
_______________
properties
- technetium has several stable ________________ states 
readily forms ______________ with _____________
- acts as _____________ by bonding to a wide range of
___________________ active substances (chosen according to
organ to be examined)
emissions
- pure _____________ emitters (decay in one step)
177
90
90
0
0
; 177
39Y  40 Zr + 1 
71 Lu  72 Hf + 1 
- Y-90  used in cancer implant therapy
-Lu-177  effective on small tumours and gamma imaging
HALF-LIFE CALCULATIONS
Calculating the percentage and amount of radioactive material decayed and remaining after a certain period of time using the
nuclear half-life equation.
t
DATA BOOKLET: Nt = No(0.5) k
*Where: Nt = the mass or amount __________________ after time t
No = the _______________mass or amount
t = time _______________
k = decay constant = ___________ –life (of radioisotope)
SAMPLE PROBLEMS:
1. a) What amount of 128
53 I will be left when 3.65 mol of this isotope is allowed to decay for 15.0 min? The half-life of
128
53
I is 25.0 min.
(b) What percentage of the sample has decayed?
2. (a) Technetium-99m has a half-life of 6.01 hours. A fresh sample containing 5.00 g of technetium-99m is prepared from
molybdenum-99 in a hospital at 0900 h. Calculate the mass at 1700 h later that day.
(b) What percentage of the sample has decayed?
*More practice problems: p. 774 of OXFORD text
SIDE EFFECTS OF RADIOTHERAPY
-Side effects mainly occur as a result of the effects of radiation on the _______________ tissue. The ionizing effects of
radiation cause changes in the ____________ of _______________ as well as _______________ cells, particularly in
those that divide ______________, such as ______________ follicles.
COMMON SIDE EFFECTS
- FATIGUE
DESCRIPTION
- _____________ and regular ________________ are important during treatment
- NAUSEA
- more common when the treatment is in the area of the ________________ system
- HAIR LOSS
- this occurs within the treatment area and is usually ________________
- STERILITY
- more likely if treatment is close to ______________ or _____________
- SKIN REACTION
- skin may become red, sore, or itchy in local area of ___________________