Radiation Safety Regs Flashcards
What are the 3 main principles of radiation protection?
- Justifcation
- Optimisation
- Limitation
Describe justification
No practice involving exposures to radiation should be adopted unless it produces sufficient benefit to the exposed individuals…. to offset the detriment it causes.
Describe Optimisation
The magnitude of individual doses, the number of people exposed… should be kept as low as reasonably achievable, (ALARA principle) economic and social factors being taken into account.
Describe Limitation
The exposure of individuals should be subject to dose limits. These are aimed at ensuring that no individual is exposed to radiation risks that are judged to be unacceptable…in any normal circumstances
Where do UK legislation come from?
3 things, 2 tiers
- ICRP 2008
- IRR17
- IMER2017
Who do the following apply to?
IRR2017
IRMER2017
IRR - staff and pubic (work activities)
IRMER - patient (medical exposures)
IRR17
Who enforces it?
- Health and Safety Executive
IRR 17
14 general measures for radiation protection
- Responsibility lies with employer
- Employer needs writted RS policy
- RP committe
- Appointment of RPA
- Radiation risk assessment
- Critical exams
- Controlled areasu
- Local Rules
- RPS
- Classified persons
- Personal monitoring
- Dose Limits (annual for staff)
- Dose investigations
- Radiation Incidents
Dose Limits
Employees > 18
Trainees < 18
Other persons
- Effective dose (mSv)
- 20, 6, 1
- Equivalent dose to lens of eye (mSv)
- 20, 15, 15
- Equivalent dose for skin (mSv)
- 500, 150, 50
- Equivalent dose1 for hands, forearms, feet and ankles (mSv)
- 500, 150, 50
All doses per calendar year, Skin dose is averaged over 1cm^2.
What are requirements for pregnant staff?
& Breastfeeding?
Pregnant
- Equivelent foetus dose should be ALARP and not exceed 1mSv
- Equivelent to 2mSv to surface of women’s abdomen
- Addition risk assessment
Breastfeeding:
- Not to work where ther is risk of intaking radionucluides
- Unsealed sources
- Additional risk assessment
Who should be classified according to IRR17?
Which types of DR work might someone need to be classified for?
What does classification involve? (x3)
Persons likely to recieve >
- 6mSv / year (whole body), 15mSv/year (eye), 150 mSv/year (extremities)
- effective dose > 20mSv or equivelent dose> dose lmit within several mins
Most commonly classified DR procedures
- Interventional radiology, flouro
Classification involves
- Regular medical survailence
- Personal monitoring my ADS
- Personal dose record kepy by CIDI
What are? & What are they used for?
IDR
TADR
TADR2000
The following are used to define controlled/supervised areas:
IDR - Instantaneous dose rate averaged over 1 min
TADR - Time averaged IDR (averaged over 8 hours, i.e. worst case scenario for a day, occupancy factor =1)
TADR2000 - TADR over 2000 hours, taking into account occupancy, use and workload.
TADR limits for controlled and supervised areas
Controlled - > 3 uSv/hour = 6mSv/year
Supervised - >0.5uSv/hour = 1mSv/year
What should an entrance to a controlled area be marked with?
- Warning notice (contolled area, x-rays, risk from radiation)
- Radiation trefoil
- illuminated warning light
Requirements of local rules (x7)
Optional content of local rules (x10)
Required
- Description of area, contolled or supervised
- Name of RPS
- Arrangements for restricting access (e.g. warning signs)
- Conditions for non-classified persons to entry, (personal dosimetry)
- Instructions for safe working to restrict exposure
- Dose investigation levels
- Contingency plans
Optional
- Managment info
- pregnant employees
- risk assessments
- contacting RPA
- staff info and training
- investigation initiation
- personal dosimetry arrangements
- testing and maintenence of safety features
- radiation and contamination monitoring
- reviewing if things are APARP and if LR are effective
What does an RPA do?
Who are they appointed by?
What must they be consulted on?
RPA’s are appointed by employers, meeting competency ctriterions by HSE
They give advice on how to follow regulations:
- Risk assess
- designating controlled/supervised areas
- investigations
- contingency plans
- dose assessment and recording
They must be consulted on:
- Controlled/supervised areas
- plans for installments
- calibration for rad monitoring
- testing of control safety features and systems of work
What does an RPS do?
- Ensure day-to-day compliance with local rules
- e.g. senior radiographer
- Liase with heads of department and RPA
- Understand precautions to be taken and what to do in an eergency
IRMER17
5 General principles of rad protection
- All diagnostic procedures havce risk
- only necessary exposures are done
- alternatives e.g. non-ionising should be sought
- all exposures are justified (risk vs benefit)
- exposures ALARP
IRMER17
Name the 3 types of dutyholders
- Referrer
- Practitioner
- Operator
IRMER17
Refferer
Job description
Requirements
Job description
- the person who reffers patients for c-rays
- registered medical practioner, dental, or other who is entitled by employer’s procedures
Requirements
- patient is uniquely identfied
- clinical information provided to justify the exposure
- information for preg
- signature
IRMER17
Practitioner
Job description
Requirements
Job description
- justifying the eposure
- medical practitioner, dental, or other entitled under emplyer procedures
Requirements
- confirms justification of exposure
- authorises request
- Normally consultant radiologist, cardio, a&e consultant
- can be delegated to an operator
- for RN procedures, practioner must have licence under ARSAC
IRMER17
Practitioner
Job description
Requirements
Job description
- practical aspects of exposure e.g. handling use of radiological equipment, asessing dose, calibration and maintenence of equipment, prep and admin of rad products
Requirements
- must be identified in procedures
- can be same as practitioner (e.g. flouro)
- One procedure can have more than 1 operator, e.g. radiologist
- operators minimise exposure time for each patient
IRMER17
MPE
Job description
Requirements
must be:
- regonised by competent authority
- closely involved in RT procedures
- involved in NM procedures and high dose CT and interventional
- available under contract
Dignostic Reference Levels
How are they defined?
Who publishes them?
How are they presented?
Do they need to be reviewed?
How are they linked to investigations?
- Established for each procedure for standard patient cohort
- published by PHE
- Local DRLs are got from dose audit
- normally given in something that’s easy to measure e.g. DAP or ESD, NOT equivelent dose
- Reviewed every 3 years or if change
- investigation required if patient dose regularly exceeds DRL
When do you report as Significant Unintended Exposure (SAUE)?
Accidental
- Adult 3mSv effective dose
- Child 1mSv effective dose
Unintended
- Depends on what the intended dose was, see ppt. too many to remember
- Either a number, or more than 10 times intended
What 3 things do you need to do research?
- Local REC approval
- Established dose constraints
- Generic risk assessments
IRMER
What needs to happen for comforters and carers?
- Informed of risks
- willingly accept dose and risk involved
- ALARP
- PPE to restict
- no dose limits, but dose constraints
- pregnant women excluded
Protection example DR:
staff and public
- Only essential people in room when x-ray is on
- stand away from patient if poss
- close doors
- minimise beam size
- PPE e.g. gloves, aprons
Protection example DR:
staff and public
Technique
- Only direct beam where it needs to be, avoid radiosensitive organs if poss, collimation, Phantoms and objects used for training
Tube & Filtration
- leakage @1m from focal spot <1mGy in 1 hour over 100cm^2, filtration marked on housing, >2.5mm Al equiv with 1.5mm permenent. Mammo >0.5mm Al
Image receptors
- Use of image intensifier, last image hold, image intensifier housing provides 2mm lead equiv shielding
Exposure factors & switches
- Flouro and radiogtraphic equipment to have AEC, CT have range of mAs, exposure swithces need continous pressure to exposure
Beam size
- Collimation, light beam diaphragm, confine beam within image receptor and area of interst
Protocols
- Standardised kV/mAs settings, pedeatrics, pulsed flouro
Exposure measurement
- AECs should display post-ecposure mAs, indication of patient dose e.g. DAP, something for skin dose in interventional radiology
