Lecture 3 Flashcards
Hazards of radiation
- Ionising radiation is harmful to living tissues, causes intracellular ionisation causing free radical production, this interferes with the molecular chemistry of the cells
- doses of radiation are cumulative - long term exposure to small does = bad
What does the damage from radiation depend on?
- The tissue irradiated
- The charectoristics of the radiation e.g x-ray
- Dose of radiation
-Time period of exposure
What tissues are most commonly effected by radiation?
Rapidly diving cells so skin, gut and gametes - gametes means that side effects can be passed onto the next generation
e.g Bone marrow, ovary/ testes, skin, GI tract, embryo (pregnant)
Effects of radiation
- inflammation
- Slowed cell growth
- Necrosis
- potential malignant change - may take years to manifest
- Genetic mutation - effects individual or future generations
e.g. skin cancer developing several years after work with X-rays has ceased
ALARA/ ALARP principle
As Low As Reasonable Achievable/ Practicable
0 won’t always be practical e.g x-raying a horse in the field
Keep doses of radiation to patients and personnel
Methods of protection
- increase space/ distance - link to the inverse square law of X-rays
- Barriers
- Protective clothing - Lead aprons and gloves
- Time - reduced time = reduced radiation dose
Barriers as a method of protection
Stone or brick wall usually sufficient enough to stop scattered radiation but not necessarily primary beam
A cavity wall is usually adequate - lead or barium plaster can be added to stop the primary beam
Protective clothing as a method of protection
Lead aprons or gloves
Only provides protection to scattered radiation, not against the primary beam
Time as a method of protection
Shortening time reduces the radiation dose
shortening examination times for certain procedures such as scinitgraphy (using radioactive isotopes) and fluoroscopy (continuous x-ray production) will reduce doses to personnel
Legislation from?
BVA guidance notes - safe use of ionising radiation in veterinary practice
Ionising radiation regulations 2017 (IRR17)
What does the legislation state practices must do?
- Notify health and safety executive that they are using radiation on the premise - part of formal notification procedures
- Have a ‘local rules’ document in place- details specific information about personnel
Who enforces the legislation
External to practice: Radiation protection adviser (RPA) - gives advice on radiation safety
Internal in practice: Radiation protection superviser (RPS) - the practice will nominate one, on daily basis will be involved with taking x-rays
What is a controlled area?
Area where the radiation dose may exceed 7.5uSv/hour
- Usually 2m around a vertical beam
only exists when xray machine is on and is connected to mains supply
- Access to this area needs to be restricted
- Must have waring signs and lights
- Can be temporary e.g. in stables
- The area will be defined with advise from the RPA
A practices local rules
- Names of RPA and RPS
- Controlled areas
- X-ray equipment being used
- Servicing and fault reporting arrangements - on an annual basis
- PPE- including safe storage and checks
- Personal dosimetry - personal monitoring of exposure
- Contingency plan (if emergency fault develops
- Record keeping - exposure book
- Written system of work e.g. training, personal permitted to be involved, access to controlled area etc.
Basic safety rules 1
- No animal should be manually restrained for radiography except in exceptional circumstances
- use positioning aids such as sand bags and foam blocks
