Chat 5

Question 1

absorption

Answer 1

Energy of the beam is transferred to the material through which it passes

Question 2

Genetic Effect of radiation

Answer 2

If defective DNA is contained in reproductive cell, then the defect may be passed along to further generations of organisms
**only occur in reproductive cells

Question 3

Radiation effects on cytoplasm

Answer 3

1. Increased permeability or rupture of membranes
2. Nonfunctional organelles such as lysosomes, endoplasmic reticulum, or mitochondria
3. Inactivation of enzymes
4. Coagulation of the cytoplasmic fluid

Question 4

Radiation effects on then nucleus

Answer 4

1. Damage in the nucleus often affects the chromosomes, which contain DNA.
2. Radiation my alter the base sequence of the DNA molecule and make it defective.
3. Defective DNA may lead to the disruption of the mechanisms for cell division (mitosis).
4. Cell division may be delayed or the reproductive capacity of the cells may be lost. Errors that are permanently incorporated into the DNA are passed on to future generations of the affected cells as mutations.

Question 5

Factors that make cells more sensitive to radiation

Answer 5

1. A high mitotic rate (it undergoes frequent cell division)
2. A long mitotic history ( it undergoes many divisions over time)
3. A primitive or immature nature (it must undergo further growth or development)
4. An undifferentiated nature (It is not highly specialized in function)

Question 6

What is the cell that is most sensitive to radiation? Why?

Answer 6

Small Lymphocyte

Highly specialized cell that is part of the immune system.. It will not divide once it is mature

Question 7

Effects of radiation immediately?

Answer 7

Do not show up immediately due to latent period

Question 8

latent period

Answer 8

Time from exposure to radiation and the signs and symptoms of biologic damage.

Question 9

What affects how long the latent period will be

Answer 9

May be as short as a few hours or as long as 20 years or more
-depends on total dose of radiation received and the amount of time it took to receive the dose

Question 10

List the Most Sensitive Cells to Least Sensitive Cells

Answer 10

1. Small Lymphocyte
Bone Marrow
Reproductive cells
Intestinal Mucosa
2. Skin
Lens of the eye
Oral mucosa
3. Connective Tissue
Small blood vessels
Growing bone and cartilage
4. Mature bone and cartilage
Salivary gland
Thyroid gland
Kidney Liver
5. Muscle 
Nerve

Question 11

Cumulative effects of radiation

Answer 11

• From repeated radiation exposure

- Radiation itself does not accumulate in tissues, but some of the unrepaired damage might.

Question 12

Cumulative effects of Radiation on the Lens of eye produces

Answer 12

Cataracts

Question 13

Cumulative effects of radiation on the bone marrow

Answer 13

leukemia

Question 14

Cumulative effects of radiation on the salivary gland

Answer 14

Cancer

Question 15

Cumulative effects of radiation on the thyroid gland

Answer 15

Cancer

Question 16

Cumulative effects of radiation on the Skin

Answer 16

Cancer

Question 17

Cumulative effects of radiation on the Gonads

Answer 17

Genetic Abnormalities

Question 18

Units for exposure to radiation

Answer 18

SI Units- Coulombs per kilogram

Old Term- Roentgen (common)

Question 19

Unit for absorbed dose by the tissues

Answer 19

gray (Gy)

Question 20

Critical Organs

Answer 20

Organs when exposed to radiation and damaged- the quality of an individuals life declines

Question 21

Skin

Answer 21

• first tissue exposed to radiation
• response to radiation is reddening or erythema
• increases risk of skin cancer
• does to the skin is substantially reduced with F speed Film and rectangular collimation

Question 22

Lens of the eye

Answer 22

• may produce cataracts
• more susceptible to radiation in children
• no longer considered a critical organ

Question 23

Thyroid Gland

Answer 23

• resistant to radiation in adults
• more susceptible to radiation in children
• Thyroid collar reduce risk by half

Question 24

Leukemia

Answer 24

• malignant changes in marrow may result in leukemia
• Marrow is found in the jaws, skull, and C-spine
• About 13% of the total bone marrow lies in the head and neck areas

Question 25

Salivary Glands

Answer 25

- moderately sensitive to radiation - association has been shown between tumors in the salivary glands and people who have received full-mouth radiographs before 20

Question 26

ALARA Concept

Answer 26

As Low As Reasonably Achievable

Question 27

Receptor Speed

Answer 27

1) Film- fastest possible speed should be used for periapicals and bitewings 2) E speed Film- no long produced; reduced exposure by at leasts 40% when compared to D speed 3) F speed film- reduces exposure by approximately 20% compared w/E speed film for a reduction of approx. 60% compared w/D speed film 4) Digital imaging receptors require less exposure than F speed 5) Charge-Coupled Device (CCD)- requires about 1/10 of radiation of D speed film

Question 28

Radiation Protection for the Patient

Answer 28

``` Receptor Speed Selection Criteria Kilovoltage Filtration Beam Collimation Cylinders Technique Proper Chemical Processing Protection ```

Question 29

Selection Criteria

Answer 29

-patients history and clinical examination rather than prescribing images routinely or according to arbitrary time tables

Question 30

Kilovoltage

Answer 30

1) Low Kilovoltage result in higher patient doses, primarily to the skin 2) 60-90 kVp; common 70 kVp

Question 31

Filtration

Answer 31

Filtration removes the low energy X-rays from the beam 1) Units operating at 70 kVp or more should have filtration equivalent to 2.5 mm of aluminum 2) Units operating at less than 70 kVp should have the equivalent of 1.5 mm aluminum

Question 32

Beam Collimation

Answer 32

1) The X-ray beam should be collimated so that is no more than 7cm in diameter at the patients face. 2) Rectangular collimation can result in a dose reduction of 50% to 90%`

Question 33

Cylinders

Answer 33

1) Open-ended circular or rectangular lead-lined cylinders are preferred for directing the x-ray beam. 2) A long cylinder will reduce the exposure to the patient more than short cylinder 3) Plastic cones are Not recommended and are illegal in some states due to scatter radiation

Question 34

Technique

Answer 34

1) receptor-holding device is recommended | 2) Retakes should be kept to a minimum

Question 35

Protection

Answer 35

1) Thyroid collars should be used on all patients for intramural imaging except when it interferes w/the examination 2) Leaded apron may not be necessary if technique is good

Question 36

Radiation protection for the operator

Answer 36

1) Operator stands behind appropriate barrier while exposing images. 2) Barrier should have window or other means of monitoring the patient 3) If no barrier, the operator should stand 6 feet away in an area that lies between 90 degrees and 135 degrees 4) Dental personnel should never hold image receptors for patients. If assistance is necessary, as a family member or guardian for help 5) Operator should never hold the tube head for stability, and if the equipment is unstable-it should not be used until it is professionally prepared. 6) Operatory that contains X-ray unit should be constructed so that it protects the people in the surrounding areas

Question 37

Prescribing images

Answer 37

The decision to obtain dental images for patients and the number or types of images to be obtained are to be determined by licensed dentists -need to obtain patient history; clinical exam