X-Ray Safety
X-rays refer to a kind of electromagnetic radiation generated when a strong electron beam bombards metal inside a glass tube. The frequency of this radiation is very high - 0.3 to 30 Ehz (exahertz or billion gigahertz). There are natural and artificial sources of ionizing radiation. Artificial sources of radiation include X-ray machines, radioactive isotopes used in nuclear medicine, gamma cameras, nuclear gauges, and nuclear power plants.
The radiation dose relates to the amount of radiation energy absorbed by the human body. To account for the way in which different types of radiation cause harm to tissue or an organ, the radiation dose is expressed as the equivalent dose in units of sievert (Sv). The dose in Sv is equal to the total external and internal "absorbed doses" multiplied by a "radiation weighting factor."
The main methods to control radiation exposure include engineering controls, administrative controls and personal protective equipment. Examples of these controls include:
- Education and training
- Reducing exposure time
- Increasing the distance from the radiation source
- Using a physical barrier that modifies the pathway between the employee and source of radiation (e.g., concrete or lead)
- Monitoring of exposures (individual and collective monitoring)
- Recording exposures
- Providing health surveillance
- Promoting a health and safety culture
- Complying with established radiation exposure (dose) limits
When operating x-ray equipment to irradiate a human, the operator must be:
- A radiation technologist registered with the New Brunswick Regulatory College for Medical Radiology Technologists,
- A dental hygienist registered with the New Brunswick College of Dental Hygienists,
- A formally trained dental assistant registered with the New Brunswick Dental Society,
- A dentist registered with the New Brunswick Dental Society,
- An interventional radiologist or an interventional cardiologist registered with the New Brunswick Medical Society,
- A chiropractor registered with the New Brunswick Chiropractors Association, or
- A student undergoing a course of instruction in a school approved by the Canadian Association of Medical Radiation Technologists, the Canadian Medical Association, the Canadian Dental Association or the Canadian Chiropractic Association.
When operating x-ray equipment to irradiate animals or items other than a human, the operator must be:
- competent in maintaining or testing of x-ray equipment,
- competent in x-ray radiation physics,
- licensed as a veterinarian by the New Brunswick Veterinary Medicine Association,
- certified as a Level I, II or III industrial radiographer, in accordance with the Canadian General Standards Board (CGSB) standard CAN/CGSB-48.9712-2014 “Non-Destructive Testing-Qualification and Certification of NDT Personnel”, or a standard offering equivalent or better protection, or
- working under the direct and close supervision of a person referred to in this list above.
While respecting the information above, any person may operate x-ray equipment, other than for the irradiation of humans, if the x-ray source, the object or part of the object being exposed to X-rays, and any detection device are enclosed in a cabinet that prevents access to and protection for persons from exposure to the X-ray beam.
X-ray equipment
An employer and an employee must make sure that the equipment is operated, maintained, inspected, and repaired according to the manufacturer’s instructions, the Radiation Emitting Devices Act (Canada), appropriate safety codes on radiation, and any other procedure approved by the Chief Compliance Officer as required.
Owners must:
- Make sure that the x-ray equipment is installed in a place that is shielded.
- Make sure that the x-ray radiation worker is not exposed to doses higher than:
Note that exposure limits to an employee can exclude natural radiation and radiation exposure from personal medical and dental procedures. Owners must also make sure that any x-ray radiation worker who is a nuclear energy worker does not exceed a combined dose of ionizing radiation that are higher than the limits in the Nuclear Safety and Control Act.
- Not allow the x-ray radiation worker to continue work that might expose them further when that employee has exceeded any of the dose limits, until the Chief Compliance Officer approves further work.
- Make sure that each employee is informed (in writing) that they are an x-ray radiation worker and what the specified dose limits are.
- Maintain records for each x-ray radiation worker, including their date of birth, gender, date of becoming an x-ray radiation worker, weekly radiation exposure and number of hours worked per week.
- When required by the Safety Codes, provide an x-ray radiation employee with a personal dosimeter, maintain each radiation exposure report for at least three years, and make sure the employee is told about their exposure within 72 hours when a single or cumulative exposure of 5.0 mSv or greater is reached unless it can be shown that the exposure will not be more than 1 mSv per year, then no ongoing monitoring or record keeping is required.
- Request, with the consent of the employee, a medical examination when there is reason to believe that the employee has received an acute whole-body does of ionizing radiation more than 500 mSv, or an extremity exposure more than 5000 mSv. This medical exam should be done during normal working hours for the employee, and any costs required paid by the owner.
Employees
An X-ray radiation worker must inform the owner of their pregnancy as soon as they become aware of being pregnant.