radiation safety

Cells most sensitive to radiation are those which divide the most actively- examples include: 

-epithelium

-hematopoietic cells

-cells lining the small intestine

-reproductive cells 

-fetus (particularly sensitive) 

Ionizing radiation can cause both;

1. Somatic (squamous cell carcinoma on hand)

2. Genetic damage (injury to reproductive cells- e.g. birth defects) 

   1. birth defects may appear in later generations

Chronic exposure of individuals to low levels of radiation is believed to produce the following effects';

1. increase in the incidence of NEOPLASIA

2. specific increase in the incidence of SQUAMOUS CELL CARCINOMA

3. Increase in the frequency of occurrence of LEUKEMIA

4. PREMATURE AGING

Increase risk in children if the expected mother was exposed to a significant amount of radiation

Risk of LEUKEMIA and other cancers

Once a women declares her pregnancy in writing, the radiation dose of the embryo/fetus shall be no greater than;  

0.05 rems (50 millirems) in any month (excluding medical exposure) 

How many months is the embryo/fetus most sensitive to radiation 

First 3 months of pregnancy 

The actual dose received by the embryo/fetus is _____ than the dose received by the mother, because ____________.

LESS, because dose is absorbed by the mother’s body.

Is there any concerns for women in about sterility or loss of ability to bear children from occupational exposure? 

No concern. 

Individuals under the age of 18 years have a greater risk of radiation injury because;

Of their more rapidly reproducing cells.

An RVT may operate radiographic equipment under;

INDIRECT supervision of a licensed Veterinarian.

An unregistered assistant may operate radiographic equipment under;

DIRECT supervision of an RVT or a licensed Veterinarian.

Personnel monitoring equipment/ devices include;

1. Film badges - most common

2. Thermolumnescent dosimeters (TLD) - most common

3. Pocket dosimeters

4. Ring -fluoroscopy

5. Wrist badges -fluoroscopy

Personnel monitors may be performed either; 

monthly or quarterly 

The essential goal of radiation safety is to prevent injury from exposure to;

Ionizing radiation

Whole body (total effective dose equivalent):

5 rems

Skin and extremities (shallow dose equivalents):  

50 rems

Lens of the eye ( eye dose equivalent):

15 rems 

X-ray beam is generated within;

a vacuum tube containing a cathode with a tungsten wire filament, and an anode target. 

Collimating device- reduction of the size of the x-ray beam improves; 

the diagnostic quality of the film by lessening the amount of fog caused by scatter radiation . 

X-ray beam filtration- The regulations specify the amount of total filtration required for veterinary x-ray machines

-at least 1.5mm of aluminum-equivalent for up to 70 kVp

-at least 2.0mm of aluminum-equivalent for over 70 kVP

The amount of inherent filtration produced by most diagnostic x-ray tubes usually ranges from: 

0.5mm to 0.8mm aluminum-equivalent 

Protective apron and gloves minimum lead requirement 

preferably 0.5mm but not less than 0.25mm

Gloves/ aprons are designed to protect the wearer from -

scatter radiation ONLY. they do not reduce the primary x-ray beam enough to provide sufficient protection.

Veterinary radiographers are responsible for adhering to all of the following radiation safety procedures: 

1. Increase or maximize the distance between the operator and source of radiation.

2. Use chemical/ mechanical restraints whenever possible to eliminate the need to hold patient. 

3. Use general anesthesia when total immobility and complete relaxation for accurate positioning.

4. Use appropriate protective devised- gowns, goggles, barriers.

5. Reduce the duration and amount of exposure.   

6. Plan radiographic procedures carefully and avoid unnecessary retakes.  

Principal factors relating to the production of quality radiographs are: 

1. Patient positioning.

2. Body part of interest should be centered of the film.

3. Body part should be perpendicular to the central main x-ray beam and parallel to the film.

4. Align the x-ray tube with the film (cassette).

5. Ensure correct focal- film distance is correct (40 in) .

6. proper techniques selection.

7. precisely measures the body part for use with  technique chart. 

What is the preferred temperature for developing solutions? 

Should not exceed 75 degrees, or fall below 65 degrees. 

Best time for developing optimal diagnostic quality films?

5 minutes at 68-70 degrees

Manual film developing rules:

1. use solutions designed for medical x-ray purposes.

2. change solutions regularly and replenish solutions.

3. avoid contaminating solutions.

4. keep films in the fixer solution for at least 10 minutes.

5. wash films in a running water bath for at least 30 minutes.

6. dry films thoroughly .

Employing/ supervising veterinarian is responsible for the following: (radiation protection)

1. Provide radiation safety rules, including any restrictions of the operating techniques

2. Ascertain each radiographer demonstrates familiarity with the radiation safety rules. 

3. Provide personnel monitoring devices. (dosimeter) 

4. Occupational exposure is to be recorded monthly or quarterly. 

5. Individual does not stand in beam, behind shield, or at least 6 feet away.

6. Surveys/ tests, quality assurance (QA) tests.

7. Report to RHB for any overexposure of personnel 

Posting and record keeping requirements (supervisor) : 

1. Department of Health Services Form current copy.

2. California Control Regulation current copy.

3. Annual report of occupational exposure must be provided to all individuals.

4. “Caution x-ray” signage.