Radiography Flashcards
What are the 4 properties of x-rays that make them particularly dangerous?
- they are invisible
- they are cumulative, and their effects build up over time
- they are latent, and their effects are not immediately obvious
- they are painless
What are the two main effect types associated with x ray exposure?
Stochastic
Non stochastic (deterministic)
Describe stochastic effects of x rays
There is a random probability that these effects could occur. The likelihood of these effects increases with misuse of xrays and repeated exposure
What are some examples of stochastic x ray effects on the body?
The most significant is cancer development
Describe non-stochastic or deterministic effects of x rays
All other effects that are possible following exposure to x-radiation
What are some examples of deterministic effects of x rays?
- radiation induced skin burns
- acute radiation syndrome (radiation poisoning)
- cataracts
- anaemia
- sterility
- DNA mutations
According to the HSE, what must exposure to x-radiation be?
ALARP - as low as reasonably practicable
Describe somatic effects of x radiation
Damage from x radiation that becomes apparent during the affected individuals lifetime. It is deterministic.
Examples include skin burns, cataracts, infertility
Describe genetic and teratogenic effects of radiation
Deterministic.
Inheritable changes, and potentially mutations in DNA. These may not affect the individual but can affect their children or even grandchildren
What are some examples of genetic and teratogenic damage by x radiation?
- chromosome changes
- stillbirths
- congenital abnormalities
- infant and childhood mortality
- malformations and teratomas
Define a TERATOGEN
Substances that cause congenital disorders in a developing embryo or fetus.
It is anything that a person who is pregnant is exposed to or ingests while they are pregnant that is known to cause fetal abnormalities
Define a TERATOMA
A tumour made up of several different types of tissue, such as hair, muscle, teeth, or bone. Typically form in the ovary, tailbone, and testicle
Describe the carcinogenic effects of x radiation
This is a stochastic effect. These concern the introduction of cancers in tissues that have been exposed to radiation. Often this is the effect of latent, cumulative exposure e.g. leukaemia
Define a CARCINOGEN
Something that causes cancers
What are the three basic principles of protection from radiation?
- use of radiation must have clear clinical justification (must be for diagnostic purposes, not a shot in the dark)
- any exposure of personnel should be kept to an absolute minimum. This can be aided by correct technique, and correct use of chemical restraints to reduce the need for repeat exposures
- no dose limit should be exceeded, and dosimeters should always be correctly used
What amount do veterinary practices have to pay under the IRR (2017)?
They have to register as medium risk workplaces and pay a fee of £25
What is some of the legislation that regulates the use of x radiation?
- the Ionising Radiation Regulations (2017)
- local radiation rules and regulations
- the Health and Safety at Work Act (1974)
- Controlled Waste Regulations (2012)
-Control of Substances Hazardous to Health (2002)
What different groups of people do x radiation dose limits apply to?
- radiation workers who are over 18 years old
- trainees who are under 18 years old
- other persons
- women of reproductive capacity
What is the dose limit rate for radiation workers who are older than 18?
20 mSv in any calendar year
What is the dose limit rate for trainees who are under 18?
6 mSv in any calendar year
What is the dose limit rate for other persons?
1 mSv in any calendar year
What is the dose limit rate for women of reproductive capacity?
13 mSv in any consecutive period of 3 months
Once a pregnancy has been confirmed and reported to the employer, the dose rate should not exceed 1mSv for the remainder of the pregnancy
When should a pregnant member of staff inform their employer?
As soon as they have a pregnancy diagnosis - risk assessments should be carried out for pregnant and breast feeding employees
Who are the people who have direct control over x radiation in practice?
Radiation Protection Supervisors
Radiation Protection Advisors
Designated Radiographers
What is the Radiation Protection Supervisor?
An authorised person who works in practice. They are responsible for enforcing safe practice and promoting the local rules and scheme of work. They work under the external RPA
What is the Radiation Protection Advisor?
Someone external to the practice. They are competent in advising employers on the safe and compliant use of ionising radiations. It is a requirement under the IRR (2017), and may be a human radiographer, or senior vet. They visit the practice once a year
Who are the designated radiographers?
These are members of practice who have had specific training in the safe use of x-rays, and how to use the equipment. They must be on the list of designated radiographers that should be visible outside the x ray room and their own dosimeter
What are the local rules?
A set of instructions for correct use of the x radiation equipment drawn up by the RPA. They set down:
- equipment details
- procedure and restriction of the controlled area
- methods of restraint
- precautions for manual restraint
- assessment of max dose likely to be received by staff
- the written scheme of work, which details step by step procedures for the radiographer
What is the controlled area?
The controlled area is 2m from the tube head. Nothing should be in this area apart from the patient.
A controlled area must be present if the x ray dose exceeds 7.5mSv per hour, or if any one person is expected to receive more than 6 mSv per year
What should warning lights for x rays indicate?
- when the machine is on
- when x rays are being produced
There should also be an audible beep
Who is responsible for ensuring x ray machine are working correctly?
The manufacturers of the machines - it is a legal requirement that x ray machines are serviced by engineers at least once a year
What groups of people should not carry out x rays?
Pregnant people, those under 16, and members of the public
Where should dosimeters be worn?
In practice only. They should be worn at all times during radiographic procedures
Where should dosimeters be kept?
Outside the x ray room, and out of direct sunlight. They pick up on all kinds of radiation, so should not be stored near microwaves or radios.
What are the two types of dosimeters?
- film badges
- thermoluminescent dosimeters
Describe film badge dosimeters
Contain a small amount of metal x ray film which determines the level of radiation exposed to
Describe thermoluminescent dosimeters
More modern than film badges. They contain radiation sensitive lithium fluoride crystals and are usually orange. The crystals change atomically when exposed to radiation
How long should records from xrays be kept?
50 years!
What different types of PPE are used for x rays?
Lead aprons, lead gloves and lead thyroid/neck protectors
How should a lead apron be stored?
Hanging up, or lying flat. It should never be folded as it could crack the lead
