Ions and Isotopes

Ions have charge
– Cations +
– Anions -

Isotopes vary in mass
– Neutrons
– Radioisotopes
 Unstable nuclei
 Emit energy -radiation
 Medical uses as tracers and treating disease
Four Primary Types of
Ionizing Radiation:
Alpha Particles
Alpha Particles: 2 neutrons and 2 protons
They travel short distances, have large mass
Only a hazard when inhaled
Four Primary Types of
Ionizing Radiation:
Beta Particles
Beta Particles: Electrons or positrons having small mass and
variable energy. Electrons form when a neutron transforms into a
proton and an electron or when a proton transforms into a positron
and a neutron:
Four Primary Types of
Ionizing Radiation:
Gamma Rays
Gamma Rays (or photons): Result when the nucleus releases
Energy, usually after an alpha, beta or positron transition
Four Primary Types of
Ionizing Radiation:
X-Rays
X-Rays: Occur whenever an inner shell orbital electron is removed
and rearrangement of the atomic electrons results with the release of
the elements characteristic X-Ray energy
Four Primary Types of
Ionizing Radiation:
Neutrons
Neutrons: Have the same mass as protons but are uncharged
They behave like bowling balls
Four Primary Types of
Ionizing Radiation

Alpha particles
 Beta particles
 Gamma rays (or photons)
 X-Rays (or photons)
 Neutrons
Ionization

Ionizing radiation is produced by unstable
atoms. Unstable atoms differ from stable
atoms because they have an excess of
energy or mass or both.
 Unstable atoms are said to be radioactive. In
order to reach stability, these atoms give off,
or emit, the excess energy or mass. These
emissions are called radiation.
Types or Products of Ionizing
Radiation

neutron

or X-ray
DNA and Radiation
Ionizing Radiation at the
Cellular Level

Causes breaks in
one or both DNA
strands or;

Causes Free Radical
formation
Commonly Transported
Radioisotopes

Americium-241= Diagnose thyroid
disorders, smoke detectors.
 Cesium-137= Cancer treatment.
 Iodine-125,131= Diagnosis & treatment
liver, kidney,heart, lung and brain.
 Technetium-99m=Bone and brain imaging;
thyroid and liver studies; localization of
brain tumors.
rad

1 rad = 1 Roentgen
rem


Roentgen Equivalent Man
The unit of dose equivalent for any type of
ionizing radiation absorbed by body tissue
in terms of estimated biological effect - Unit
of dose equivalent
 Dose in health record is in units of rem
 1 rem = 1 Roentgen
 1 Sievert (Sv) = 100 REM
 1 mSv = 100 mREM
Quality Factor (Q)
The specific value that accounts for the
ability of different types of ionizing
radiation to cause varying degrees of
biological damage
– X-rays, gamma rays, & beta particles
– Neutrons & High energy protons
– Alpha Particles
1
10
20
Units of Radioactivity

Curie (Ci) = 2.22 E12 dpm or 3.7E10 dps
 Becquerel (Bq) = 1 dps
 Maximum Dose/year = 5 REM or 50 mSv
 Maximum Dose/year for Declared Pregnant
Woman & Minors= 0.5 REM or 5 mSv
Half Life Calculation
Annual Dose Limits
External/Internal Exposure Limits for Occupationally Exposed Individuals
Adult ($18 yrs)
Minor (< 18 yrs)
Whole body*
5000 mrem/yr
500 mrem/yr
Lens of eye
15000 mrem/yr
1500 mrem/yr
Extremities
50000 mrem/yr
5000 mrem/yr
Skin
50000 mrem/yr
5000 mrem/yr
Organ
50000 mrem/yr
5000 mrem/yr
Dose Response Relationships

0-150 rem—No or minimal symptoms
 150-400 rem—Moderate to severe illness
 400-800 rem—Severe illness deaths start
above 500 rem
 Above 800 rem—Fatal
***Acute whole body doses
Your Annual Exposure
Activity
Smoking
Typical Dose
280 millirem/year
Radioactive materials use
in a UM lab
<10 millirem/year
Dental x-ray
Chest x-ray
Drinking water
Cross country round trip by
air
Coal Burning power plant
10 millirem per xray
8 millirem per xray
5 millirem/year
5 millirem per trip
0.165
millirem/year
Effective doses of ionizing radiation from medical
procedures
Subjects
Total
Subjects undergoing more
subjects (n) than 1 procedure (%)
Mean annual effective
dose from procedures
(mSv)
All subjects
952 420
68.8
2.4
•Males
•Females
•18–34 y
•35–39 y
•40–44 y
•45–49 y
•50–54 y
•55–59 y
•60–64 y
453 078
57.9
2.3
499 342
78.7
2.6
233 586
49.5
1.0
118 365
65.7
1.6
144 728
72.1
2.0
146 703
74.9
2.6
131 209
78.2
3.3
115 520
79.5
4.1
62 309
85.9
5.2
Fazel R et al. N Engl J Med 2009; 361: 849-57.
Medical imaging procedures with largest
contribution to cumulative effective dose
Procedure
Average effective dose
(mSv)
Proportion of the total
effective dose from all
study procedures (%)
Myocardial perfusion imaging
CT of abdomen
CT of pelvis
CT of chest
Diagnostic cardiac catheterization
Radiography of the lumbar spine
Mammography
CT angiography of the chest
(noncoronary)
Upper gastrointestinal series
CT of head or brain
PCI
15.6
8
6
7
7
1.5
0.4
15
22.1
18.3
12.2
7.5
4.6
3.3
3.1
3.1
6
2
15
2.4
2.0
1.8
Fazel R et al. N Engl J Med 2009; 361: 849-57.
Estimated Exposure To The
National Population
Between
320 – 360 mr/yr