1. Atoms, Ions, and Molecules
Chapter 2
Atoms, Ions, and Molecules

2. About this Chapter Make up of atoms, ions, & molecules
Bonds combine atoms, form molecules
Concentrations
Biomolecules

3. Figure 2-1: Atomic structure
Atoms and Elements
Structure of an atom
Protons
Electrons
Neutrons
Mass
Charge
Nucleus
Electron orbitals
Elements
Essential & trace elements
Figure 2-1: Atomic structure

4. All the Elements
Figure 2-2: Periodic table of the elements

5. Elements of the Body

6. Elements other than C, H, O and N in Humans
Primary Elements (3% of all body weight)
Calcium Ca Bones, teeth, muscle and nerve action, blood clotting
Phosphorus P Bones and Teeth, DNA, RNA, ATP. Important in
energy transfer
Trace Elements (Less than 1 % of body weight altogether)
Potassium K Osmotic balance; cell voltage, muscle and nerve
action
Sulfur S Component of proteins (cysteine) and other organic
molecules
Sodium Na Osmotic balance; cell voltage, muscle and nerve
Chlorine Cl Osmotic balance; cell voltage, muscle and nerve
Magnesium Mg Co-factor for many enzymes
Iron Fe Hemoglobin and many enzymes
Copper Cu Co-factor of many enzymes
Zinc Zn Co-factor of many enzymes
Manganese Mn Co-factor of many enzymes
Cobalt Co Co-factor of many enzymes and vitamin B12
Chromium Cr Co-factor of many enzymes and potentiates Insulin
Selenium Se Required for normal liver function
Molybdenum Mo Co-factor of many enzymes

7. Ions and Isotopes Ions have charge Cations + Anions -
Isotopes vary mass
Neutrons
Radioisotopes
Unstable nuclei
Emit energy -radiation
Medical uses as tracers

9. Ions and Isotopes
Figure 2-3: A map showing the relationship between elements, ions, isotopes, and atoms

10. 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

11. 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:

13. 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
A gamma particle is a photon. It is produced as a step in a radioactive decay chain when a massive nucleus produced by fission relaxes from the excited state in which it first formed towards its lowest energy or ground-state configuration.

14. 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

15. In the medical field, useful X-rays are produced when electrons are accelerated to a high energy. The X-rays themselves are produced by the rapid deceleration of electrons in a target material, typically a tungsten alloy, which produces an X-ray spectrum via bremsstrahlung radiation. Some examples of X-ray energies used in medicine are:
superficial X-rays - 35 to 60 keV
diagnostic X-rays - 20 to 150 keV
orthovoltage X-rays - 200 to 500 keV
supervoltage X-rays - 500 to 1000 keV
megavoltage X-rays - 1 to 25 MeV

16. --Superficial radiation therapy (SRT) machines produce low energy x-rays in the same energy range as diagnostic x-ray machines, kV, to treat skin conditions.
--Orthovoltage X-ray machines, which produce higher energy x-rays in the range kV. These are known as "superficial" or "deep" machines depending on their energy range. Orthovoltage units have essentially the same design as diagnostic X-ray machines. These machines are generally limited to less than 600 kV.
--Linear accelerators ("linacs") which produce megavoltage X-rays. The first use of a linac for medical radiotherapy was in 1953 (see also Radiation therapy). Commercially available medical linacs produce X-rays and electrons with an energy range from 4 MeV up to around 25 MeV. The X-rays themselves are produced by the rapid deceleration of electrons in a target material, typically a tungsten alloy, which produces an X-ray spectrum via bremsstrahlung radiation. The shape and intensity of the beam produced by a linac may be modified or collimated by a variety of means. Thus, conventional, conformal, intensity-modulated, tomographic, and stereotactic radiotherapy are all produced by specially-modified linear accelerators. Megavoltage X-rays are by far most common in radiotherapy for treatment of a wide range of cancers. Superficial and orthovoltage X-rays have application for the treatment of cancers at or close to the skin surface.
--Cobalt units which produce stable, dichromatic beams of 1.17 and 1.33 MeV, resulting in an average beam energy of 1.25 MeV. The role of the cobalt unit has partly been replaced by the linear accelerator, which can generate higher energy radiation. Cobalt treatment still has a useful role to play in certain applications (for example the Gamma Knife) and is still in widespread use worldwide, since the machinery is relatively reliable and simple to maintain compared to the modern linear accelerator.

17. Four Primary Types of Ionizing Radiation: Neutrons
Neutrons: Have the same mass as protons but are uncharged
They behave like bowling balls

18. --Fast neutron therapy utilizes high energy neutrons typically between 50 and 70 MeV to treat cancer. Most fast neutron therapy beams are produced by reactors, cyclotrons (d+Be) and linear accelerators. Neutron therapy is currently available in Germany, Russia, South Africa and the United States. In the US three treatment centers operate in Seattle, Washington, Detroit, Michigan and Batavia, Illinois.
--Radiation therapy kills cancer cells in two ways depending on the effective energy of the radiative source.
--Low Linear Energy Transfer radiation damages cells predominantly through the generation of reactive oxygen species free radicals. The neutron is uncharged and damages cells by nuclear interactions. Malignant tumors tend to have low oxygen levels and thus can be resistant to low LET radiation. This gives an advantage to neutrons in certain situations.

19. Proton Therapy
One of the most exciting advances in the fight against cancer – proton therapy – is coming soon to Miami Cancer Institute. When it opens in 2017, the Proton Therapy Center will be the only center of its kind in the region and one of only 14 in the United States.
An advanced form of radiation treatment, proton therapy spares healthy tissue and eliminates many of the side effects of conventional radiation treatment (also known as photon or external beam radiation). It shoots from 360 degrees around the patient. Miami Cancer Institute will feature three proton treatment rooms with the newest form of proton therapy – called pencil-beam scanning – the most precise and accurate way to deliver radiation to a tumor. While traditional X-rays pass through healthy tissue and organs on their way in and out of the body, protons travel through the body and release most of their energy inside a tumor. Using proton therapy reduces the risk of damage to bones and soft tissues and decreases the odds of other tumors later in life, which makes it particularly good for treating childhood cancers.

20. Four Primary Types of Ionizing Radiation
Alpha particles
Beta particles
Gamma rays (or photons)
X-Rays (or photons)
Neutrons

22. How this can be dangerous
How we can protect ourselves
- Types will be discussed later
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.

23. Types or Products of Ionizing Radiation
- Symbols
Types or Products of Ionizing Radiation  
or X-ray
neutron

24. DNA and Radiation

25. Ionizing Radiation at the Cellular Level
Causes breaks in one or both DNA strands or;
Causes Free Radical formation

27. 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.

28. rad 1 rad = 1 Roentgen - 3 bullets will transition 1 by 1 - 1953
- dose relates to an irradiated medium
- 1 Roentgen equivalent to 95 ergs/g of tissue
- gamma vs. neutron (LET)

29. 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
- 5 bullets will transition 1 by 1
- For biological damage (tissue) purposes

30. 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 1
Neutrons & High energy protons
Alpha Particles
- Table Pg. 5
- Function of LET
- Higher LET - Higher Q

31. 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
          

32. Half Life Calculation

33. *Effective dose equivalent
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
Skin
Organ
*Effective dose equivalent

34. Dose Response Relationships
rem—No or minimal symptoms
rem—Moderate to severe illness
rem—Severe illness deaths start above 500 rem
Above 800 rem—Fatal
***Acute whole body doses
0-150 Perhaps increased cancer with long latency\\\ increased cancer risk GI damage at higher rates

35. Your Annual Exposure Activity Typical Dose Smoking 280 millirem/year
Radioactive materials use  in a UM lab
<10 millirem/year
Dental x-ray
10 millirem per x-ray
Chest x-ray 
8 millirem per x-ray
Drinking water 
5 millirem/year
Cross country round trip by air 
5 millirem per trip 
Coal Burning power plant
0.165 millirem/year 

39. Estimated Exposure To The National Population
Between 320 – 360 mr/yr