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radiography – local rules

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Every dental practice with radiographic (x-ray) equipment is required to provide a set of “local rules”.  These record all the working practices we must follow to ensure that we are safe when working with radiation and that we comply with the various regulations governing radiation in dentistry; in particular the Ionising Radiations Regulations 1999 (IRR99).  This document contains the “local rules” that apply to Hygeia Dental Care’s premises at Malt Mill Lane, Totnes.

duties of employees

All clinical personnel must:

a) Ensure that exposures to staff and all other people are kept as low as reasonably practicable;
b) Take reasonable care when working with any aspect of dental radiography – in particular, radiography must be conducted with due regard to minimising accidental or unintended doses to patients;
c) Immediately report to the RPS (Joanne Giddy) any incident that may result in the overexposure of themselves or anyone else.

All clinical personnel have a duty to exercise reasonable care and act responsibly in relation to radiography.  They are required to know and observe these rules at all times.

x-ray equipment at Malt Mill Lane

There are two x-ray units at Malt Mill Lane:

unit 1

location treatment room 1
manufacturer Trophy Trex
model IRIX 70 – Trophy CCX
serial no. 875097
manufactured 23/6/98
installed 15/10/98
operating potential 67kV
total beam filtration >2.0mm Al
beam profile 33mm x 42mm (with collimator)
focal spot to skin distance 200mm
optimum dose for imaging 0.97mGy (digital sensor – adult mandibular molar)
patient skin dose 0.41mGy (digital sensor – film type 5 – adult mandibular molar)

unit 2

location treatment room 2
manufacturer Trophy Trex
model IRIX 70 – Trophy CCX
serial no. 921048
manufactured 20/7/99
installed 8/99
operating potential 71kV
total beam filtration >2.3mm Al
beam profile 32mm x 42mm (with collimator)
focal spot to skin distance 200mm
optimum dose for imaging 0.89mGy (digital sensor – adult mandibular molar)
patient skin dose 1.10mGy (digital sensor – film type 6 – adult mandibular molar)

 

important note:   The garden area outside must be unoccupied whilst x-rays are being taken.

It is the responsibility of Joanne Giddy (the RPS – see below) to notify the Health and Safety Executive of the use of, and any changes to, the radiography equipment in use at the premises.

radiation protection adviser & medical physics expert

Public Health England Dental X-ray Protection Services (formerly known as the Health Protection Agency Radiation Protection Division; formerly known as the NRPB) has been appointed as Radiation Protection Adviser (RPA) and Medical Physics Expert (MPE) to Hygeia Dental Care in respect of its premises at Malt Mill Lane, Totnes in accordance with Regulation 13 of IRR99 and the Ionising Radiation (Medical Exposure) Regulations 2000 (“IRMER”).  Our primary contact is Sharon Ely.  She can be contacted on 0113 212 7430.

radiation protection supervisor

Joanne Giddy is the appointed Radiation Protection Supervisor (RPS) for Hygeia Dental Care’s premises at Malt Mill Lane, Totnes.  It is her responsibility to ensure that all persons working at the practice observe these local rules and that they comply with IRR99, any other relevant statutory instruments and relevant guidance published by competent professional and statutory bodies.

The RPS (Joanne Giddy) must undergo regular training in radiography (covering the relevant topics set out in IRMER Schedule 2) totalling at least 5 hours of verifiable CPD (Continuing Professional Development) every five years.

It is the responsibility of the RPS to periodically review and (in consultation with the RPA/MPE) update these local rules.

controlled and supervised areas

The IRR specify “controlled” and “supervised” areas in relation to dental intra-oral x-ray equipment.

controlled areas

When either x-ray unit is operating, a “controlled area” exists.  A controlled are is somewhere that you MUST NOT GO while the x-ray unit is in operation.  When an x-ray is being taken in surgery 1, the whole of that room is a controlled area.  When an x-ray is being taken in surgery 2, the whole of that room is a controlled area.

supervised areas

There are no supervised areas outside the controlled areas defined above.  All that clinical personnel need to know about supervised areas is that there are none.  Just be sure to stay out of the controlled areas when the x-ray unit is in operation.

classified persons and written system of work

There are no “classified persons” on our team and the provisions on written systems of work do not apply.

x-ray equipment – testing, servicing, maintenance & repair

All x-ray units at Malt Mill Lane must be subjected to a radiation safety assessment at least once every 3 years.  It is the responsibility of the RPS (Joanne Giddy) to ensure that this is done.  Radiation safety assessments are carried out using standard HPA test packs.  It is the responsibility of the RPS (Joanne Giddy) to ensure that any recommendations made as a result of the assessments are acted upon within 3 months.

All x-ray units at Malt Mill Lane must undergo routine servicing at least once every year.  It is the responsibility of the RPS (Joanne Giddy) to ensure that this is done.  Servicing is undertaken by Edwards Dental who can be contacted on 01803 555739 or 07921 101111.

All x-ray units at Malt Mill Lane must undergo routine surveillance at least once every 6 months.  Routine surveillance checks the correct functioning of the audible and visual warning systems, exposure controls, x-ray arm counterbalance mechanism and condition of the x-ray tube head.  It is the responsibility of the RPS (Joanne Giddy) to ensure that this is done and to arrange for any necessary repairs to be carried out.  Repairs are undertaken by Edwards Dental who can be contacted on 01803 555739 or 07921 101111.

Computer monitors used to view x-ray images at the practice (which means all of them) undergo testing every 3 months to ensure that they are correctly calibrated and reproduce images with good detail, contrast and without distortion.  The results are recorded in section 7 of the Radiation Protection File.  Monitors that do not perform acceptably must be replaced.

Digital x-ray sensors and imaging software used to capture x-ray images undergo testing every 3 months to check sensor condition, image uniformity, low contrast sensitivity and sensor dose response.  The results are recorded in section 7 of the Radiation Protection File.  Sensors (or software) that do not perform adequately must be replaced.

No-one is permitted to interfere with or modify any part of the x-ray equipment unless they have first referred the matter to the RPS (Joanne Giddy).

Following any testing, servicing, maintenance or repair work, no x-ray unit or ancillary equipment may be accepted back into service until the RPS (Joanne Giddy) has reviewed the service report.  This should confirm that the equipment has been left in a state fit for use and that no alterations have been made which may significantly affect patient doses.  If such alterations have been made, the RPS (Joanne Giddy) should seek advice from the RPA/MPE before bringing the equipment back into use, since a critical examination may be required first.

use of x-ray equipment/working procedures

The x-ray equipment must only be operated by a suitably qualified person, or by a person under their supervision who has received adequate training and instruction in the use of the x-ray equipment.  At Malt Mill Lane only Joanne Giddy is qualified to operate the equipment.

The exposures used for radiography must be no greater than those required to yield correct radiographic densities with complete development of the film.  The exposure timings for both x-ray units are pre-set.  The correct film speed settings are selected using the “f” button on the control box.  The practice uses digital sensors.  The correct setting for these is film type 3 in surgery 1 and film type 6 in surgery 2.  The controls must also be set for the appropriate anatomical view.  For other film types and guidance on adjustments to exposure times to compensate for patient size, refer to the IRIX 70 user’s manual.

The operator of the x-ray equipment must take up a position outside the main x-ray beam and where the instantaneous dose rate does not exceed 7.5 microsieverts per hour.  For both x-ray sets the appropriate operator position is outside the door of the room.  The operator must ensure that they are able to view both the warning light on the control hand-switch and the patient during radiography. Electronic viewers installed on the doors permit the operator to view the patient from outside the room. The hand-switch controlling the exposure is on an extendable curly-cable and is brought outside the room by the operator so that the warning light remains visible.

The operator must also ensure that the x-ray tube head is never directed toward a window, a door or an unshielded partition wall.  If this appears to be the case, the patient must be repositioned before the exposure is taken so that the tube head is pointing toward an external wall or shielded internal wall.

The operator must ensure that any personnel who do not routinely work in the surgery (reception and administration personnel, for example) are not present in the room when x-rays are taken.

The operator is supplied with and is required to use x-ray film holders with integral beam alignment devices.  These have been proven to reduce the number of radiographs that are judged unacceptable by reason of positioning errors, thereby reducing the overall number of x-rays taken and x-ray exposure for clinical personnel and patients alike.

During every radiographic examination the operator must observe the radiographic warning light to check that the exposure terminates correctly.  X-ray sets must be turned off (using the switch on the control panel) when not in use.

damage to x-ray equipment

If an x-ray unit is damaged, immediately isolate the unit from the mains electricity supply.  To do this, simply switch the power off using the switch on the front panel of the x-ray control unit.  The x-ray control unit is the box on the wall near the surgery entrance door (to which the remote switch is attached).  Next, switch off the supply circuit labeled “X-ray unit” (circuit breaker number 3) at the consumer unit in the relevant surgery.  Notify the RPS (Joanne Giddy) of the damage immediately.  Do not use the x-ray unit again until the malfunction has been investigated by the RPS (Joanne Giddy) and any necessary remedial action has been taken by service agents.  Servicing is undertaken by Edwards Dental Equipment Services who can be contacted on 01803 555739 or 07921 101111.

contingency plans

If the exposure warning light remains on after the set time has elapsed, or any other fault is indicated or suspected, immediately isolate the x-ray unit from the mains electricity supply.  To do this, simply switch the power off using the switch on the front panel of the x-ray control unit.  The x-ray control unit is the box on the wall near the surgery entrance door (to which the remote switch is attached).  Next, switch off the supply circuit labeled “X-ray unit” (circuit breaker number 3) at the consumer unit in the relevant surgery.  Notify the RPS (Joanne Giddy) of the malfunction immediately.  Do not use the x-ray unit again until the malfunction has been investigated by the RPS (Joanne Giddy) in consultation with the RPA/MPE, a satisfactory explanation has been found and remedial action has been taken by service agents.  Servicing is undertaken by Edwards Dental who can be contacted on 01803 555739 or 07921 101111.

accidental over exposure

If it is suspected that a patient undergoing a medical exposure (or any other person) may have been exposed to ionising radiation to an extent much greater than intended, the incident must be reported immediately to the RPS (Joanne Giddy).  She must investigate the incident immediately in consultation with the RPA (ie the HPA).  Unless the investigation shows beyond reasonable doubt that no such incident occurred, it must be notified to the Health and Safety Executive on 0117 988 6000.  Arrangements must be made for a detailed investigation of the circumstances of the exposure and an assessment of the dose received.

dose investigation level

The formal dose investigation level set by this practice is 1mSv (refer to Radiography Risk Assessment – see section on IRR, regulation 21: Dose Assessment).  Should any member of staff receive an annual dose exceeding 1mSv, the RPS (Joanne Giddy) must conduct a formal investigation in liaison with the RPA/MPE in order to establish why.  The results of any such investigation must be kept for at least 2 years.

pregnancy – clinical personnel

All clinical personnel must inform the RPS (Joanne Giddy) as soon as they become aware that they are pregnant.  This is because working with ionising radiation carries certain risks for a developing foetus.  Compliance with these local rules should normally mean that no special precautions are necessary.  However, the RPS (Joanne Giddy) will consult the RPA/MPE and, if required, implement changes to working practices for the pregnant team member to ensure that the dose to the foetus of any member of staff is unlikely to exceed 1mSv during the declared term of pregnancy.

pregnancy – patients

Pregnant patients only present safety issues in connection with dental radiography when a radiographic examination would result in irradiation of the pelvic area by the primary x-ray beam (eg where a vertex occlusal projection is required).  We do not use such projections on adult patients and therefore this can never be an issue.

Nonetheless, we always identify pregnant patients as part of our clinical risk management procedures by means of medical history taking (treatment code EMED1) and medical history updates (treatment code EMED2).

Where a patient knows or suspects that they are pregnant, then they are – unless there is an urgent need for treatment and radiographic examination is essential – advised that they may defer radiographic examination if they prefer.

assistance with radiography

Clinical personnel must never support the x-ray tube head, or the patient, or hold a sensor in position for the patient.  Whenever a patient requires assistance during a radiographic examination seek the advice of our Radiation Protection Adviser – this is DXPS at PHE who can be reached on 0113 2127430.

film processing

The practice no longer uses wet film systems, so all sections in older editions of these local rules relating to film processing, preparation of solutions, storage of solutions, replacement of solutions, processing times and temperatures and mounting of radiographs no longer apply.

radiographic quality control

When reviewing x-rays, the dentists must note any deterioration in image quality.  If there is any deterioration in quality, they must consider whether this is a result of errors in positioning or exposure.

Errors of positioning should be virtually eliminated by the beam alignment devices provided.  If not, the operator must adjust his or her technique to improve results.

Exposure times are pre-set on the x-ray units at the practice.  This minimises the possibility of error.

Processing errors are no longer possible (because we use a digital system), so a loss of image quality may indicate a malfunction in the x-ray unit or the digital x-ray sensor and the RPS (Joanne Giddy) must be informed.  It is her responsibility to investigate the matter and, if necessary, arrange for the x-ray unit, sensors and software to be checked if she suspects there may be a fault.  In her absence, the operator should consult the RPA.  If it is necessary to arrange for the unit to be checked, contact Edwards Dental on 01803 555739 or 07921 101111.

The practice aims to achieve the following x-ray quality targets:

a) Not less than 70% of x-rays should be of “excellent quality” – with no errors of exposure or positioning

b) Not more than 20% of x-rays should be of only “acceptable quality” – with some errors of exposure or positioning but which do not detract from the diagnostic utility of the radiograph

c) Not more than 10% of x-rays should be of “unacceptable quality” – with errors of exposure or positioning which render the radiograph diagnostically unacceptable

If an operator becomes aware that the quality of films has fallen significantly below these targets, they must inform the RPS (Joanne Giddy) immediately.  She must then take action to ensure that overall quality is improved.

The RPS (Joanne Giddy) is responsible for carrying out audits of radiographic image quality at six monthly intervals.  The results of these audits are recorded in our Radiation Protection File.  If the quality targets set out above are not met, she is responsible for taking action to ensure that overall quality is improved.

The practice also carries out biannual audits of reject x-ray images to determine the causes of clinically unacceptable images and to determine whether any patterns arise that may allow corrective action to be taken.

All x-ray images are graded as “excellent” (grade 1), “acceptable” (grade 2) or “unacceptable/reject” (grade 3) on the day they are taken and this is recorded in the patient notes.  This ensures that any changes in image quality are noted as soon as they occur.

clinical evaluation of x-rays

Clinical evaluation of x-ray images is carried out by Joanne Giddy (who is also the RPS and is the only referrer/operator/practitioner for the purposes of IRMER at this practice) immediately after the image is taken.  This is possible since the image is captured using a digital CCD system and it is therefore available to view only a few seconds after the exposure.  Any caries revealed or other findings relevant to the patient’s management or prognosis are recorded in the patient’s electronic notes during the course of or immediately after their appointment.

referral and justification of x-rays

This practice follows the procedures outlined in ss2.29 to 2.35 of “Guidance notes for dental practitioners on the safe use of x-ray equipment” published by the National Radiological Protection Board in 2001 and the more detailed good practice guidelines entitled “Selection Criteria for Dental Radiography” published by the Faculty of General Dental Practitioners (UK) of the Royal College of Surgeons of England, 3rd edition (2013).

This practice does not carry out x-ray exposures for purely medico-legal reasons nor at the request of third parties.

risk assessment

The practice is required to carry out, record and periodically review a risk assessment for work with x-rays.

It is the responsibility of the RPS (Joanne Giddy) to ensure that the risk assessment is reviewed, updated and any necessary action taken to maintain safe working practices and/or compliance with current regulations.  The risk assessment must be reviewed annually AND:

a) whenever new radiographic techniques or equipment are introduced for the first time (eg first use of panoramic radiography or cephalometry);

b) whenever there are changes to the process or methods of work;

c) whenever new legislation is introduced relating to radiography.

The latest risk assessment is published on this website.

training

All new members of the team receive essential training in relation to the local rules as part of their induction process.  The RPS (Joanne Giddy) must ensure that existing members of the team maintain their knowledge of the local rules and that appropriate training is given either by way of providing written or oral instructions, or at a special training session.

disposal of radiographic waste

Since the practice now uses a digital x-ray system, we no longer produce the associated waste products: lead foil from x-ray wrappers, x-ray developer solution and x-ray fixer solution.

 

Web version 15: 3.9.2017
Previous local rules published: 27.7.2006; 10.4.2008; 9.8.2008; 2.4.2009; 26.1.2012; 23.2.2012; 27.4.2012; 17.12.2012; 13.3.2013; 19.6.2014; 11.4.2015; 3.7.2015; 4.8.2016; 20.10.2016 (reviewed 1.9.2017)

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