Unit 6 Radiation Protection

Patient Protection Before Exposure

• Proper prescribing of dental images

• The use of equipment that complies with provincial & federal radiation guidelines.

When should image (x-ray) be taken?

only prescibe when its necessary

Who can prescribe dental radiograph?

• Dentist

• Hygienist

• Denturist

How many images should a patient require?

• The # of films and frequency should be assessed on an individual basis.

• There is no predetermined number!

What are Guidelines for Prescribing Radiograph

 New or a recall patient?

 Risk factors for caries?

 History of periodontal disease?

 Assess growth and development?

 Age of the patient?

• Primary, mixed or permanent dentition?

• Dentulous or edentulous?

Requirements For Dental X-ray Equipment (protecting the patient prior to exposure

Filtration

Collimation

PID

Filtration

• The function of the aluminum filter is to filter out soft x-rays.

• Those soft x-rays are harmful to the patient and do not add any diagnostic value to the image.

• Filtration results in a higher energy and more penetrating beam.

What is the requirements for filtration?

• hinger than 70 kvp you need 2.5 mm pf aluminum

• 70 kvp or low you need 1.5 mm of aluminum

Collimation

The lead collimator restricts the size and shape of the x-ray beam

which reduces the patient’s exposure

A rectangular collimator exposes ___ less tissue than a circular collimato

60%

Requirements from Health Canada for collimation is to restrict the beam size to:

• 7cm for the circular collimation.

• 38.5cm2 for the rectangular collimation.

What PID length is preferred?

longer is preferred because of less divergence

Patient protection during exposure

• Thyroid collar & Lead apron

• Beam Alignment Devices

• Exposure factors

• Proper techniques

What protects the person form scatter radiation?

Thyroid Collars and Lead Aprons

Beam Alignment Devices / Receptor Holder

• Stabilize - less chance for movement.

• Patient does not have to hold the recepto

Exposure factors

• 60-80 kV

• 6-8 mA

• Shortest exposure time possible to create a diagnostic image

What are the proper techniques?

• The radiographer must be knowledgeable in all the techniques.

• Being organized reduces the chances of a double exposure or a retake (additional exposure to the patient

Protecting the Operator

Avoid the primary beam:

• Never hold a receptor in place for a patient.

• Never hold the tubehead during exposure

In Canada, according to Safety Code 30, the minimum distance

is?

3 meters

Radiation Monitoring

 Dental x-ray equipment in Alberta must be registered with the

Alberta Dental Association & College (ADA&C)

 On-site radiation monitoring must be done by qualified service

personnel an Authorized Radiation Protection Agency.

(There are 4 ARPA in Alberta)

 Once equipment is registered, full compliance verification is

required every 5 years.

• Each owner must provide the ADA & C annual confirmation

of facility registration, including evidence of dosimetry service

and management of Quality Assurance.

 Failure to meet the requirements of this program may result in

suspension of the practice!

What is the ONLY way to monitor personnel exposure to ionizing radiation

Dosimeters

Exposure Limits

MPD = maximum permissible dose

✓ for radiation workers is 50 mSv/year.

✓ for pregnant radiation workers is 4 mSv (during pregnancy)

✓ For general public or students in training is 1 mSv/year

Radiation Safety Legislation

◼Federal

Safety Code 30 (Health Canada)

◼Provincial

Radiation Protection Act

Radiation Protection Regulation

What is the ALARA principle?

As Low As Reasonably Achievable