S.I. No. 250/1998 - European Community (Radiological and Nuclear Medicine Installations) Regulations, 1998

1. Means of preventing emission of radiation when the exposure switch is not activated.

2. Visual means of indicating the state of charge of the high potential capacitor.

3. Means of discharging the high potential capacitor to less than 30 volts without producing radiation.

Radiation Output

a.

Indication

The current and exposure time settings (or mAs setting) should be clearly indicated on the control panel.

b.

Magnitude

The radiation output measured at 1 metre from the focal spot should be in the range: -

25 - 75m Gy/mAs for single phase units

40 - 115m Gy/mAs for three phase units

with the voltage set at 80 kVp

c.

Consistency

The radiation output shall be constant for repeated exposures within :-

10% for single phase units

5 % for three phase units

d.

Variation with change in selected current

The variation shall be within:-

15% for single phase units

10% for three phase units

e.

Variation with selected mAs

The variation shall be linear within

20% for single phase units 10% for three phase units

f.

Variation with selected kV

The radiation output should vary according to the square of the selected tube voltage.

Timer Accuracy

The actual exposure time shall be within 10% of the selected exposure time.

Field Size

General purpose radiographic equipment shall be provided with an adjustable collimator which provides adjustment of the field size and with a light beam diaphragm.

When the axis of the x-ray beam is perpendicular to the plain of the image receptor, the centres of the x-ray field and the image receptor shall be aligned to within 2% of the source - image receptor distance.

The sum of the misalignment of any two opposite edges of the visually defined field with the respective edges of the x-ray field shall not exceed 3% of the distance from the source to the centre of the visually defined field, and the sum of the deviations in two perpendicular directions shall not exceed 4%.

3.

FLUOROSCOPY

In addition to the requirements for general radiography the following additional requirements hold for fluoroscopy systems.

Imaging devices

Equipment for fluoroscopy shall be provided with the means of confining the radiation beam to the image receptor area whatever the distance between tube and receptor.

Image intensifiers and TV systems shall be used as the image registration systems in fluoroscopy.

The housing of the image intensifier shall provide shielding equivalent to at least 2 mm Pb for use up to 100 kVp, or 2.5 mm Pb for use up to 150 kVp.

Exposure switches

Footswitches shall be designed to prevent inadvertent production of x-rays. If resetting of the timer is automatic then a further exposure should only be possible if pressure has been released completely from the switch.

In addition to the mechanical means of terminating screening via the switches there shall be provision for automatic termination after a predefined screening time not exceeding 10 minutes. The device shall give an audible signal before termination to enable the operator to reset the system if the exposure time needs to be extended.

Fluoroscopy systems that utilise both hand and foot switches shall be designed so that one or the other switch is operational at one time but not both simultaneously.

Operator protection

Adequate protection for staff against scattered radiation shall be provided on tables and stands used for fluoroscopy.

Patient doses

Dose-Area product meters should be fitted to fluoroscopy equipment in hospitals which undertake radiological training.

The skin entrance air-kerma rate shall not exceed 100 mGy/min and should not exceed 50 mGy/min at the shortest focal spot to skin distance specified for the equipment.

4.

COMPUTERISED TOMOGRAPHY (CT)

The following additional requirements hold for CT in addition to those for general radiography.

Shield size

The radiation beam should have no cross sectional dimension greater than that required to cover the active element of the radiation detector.

Shielding

The housing should provide shielding equivalent to at least 2.5 mm Pb.

Automatic exposure termination

The exposure should terminate as soon as the selected scan has been completed or scanning stops. If scanning mode is selected an exposure should not be possible if there is a failure of the scanning motor.

Emergency Stop

There shall be a simple mechanism to terminate an exposure in an emergency.

5.

MAMMOGRAPHY

Focal spot

The position of the focal spot shall be clearly marked on the tube housing.

The focal spot should have dimensions ≤ 0.5 x 0.5 mm. If magnification is to be performed then the focal spot should be ≤ 0.2 x 0.2 mm.

Filtration

The total filtration of the assembly should be ≥ 0.5 mm. Al or ≥ 0.03 mm Mo. The total filtration should be clearly marked on the tube housing.

For units equipped with changeable filters there shall be a clear indication which filter is selected.

The tube voltage should range between 25 and 35 kVp. The kVp setting on the control panel should be accurate to 1 kV and shall be within 2 kV of the dial setting.

Mains compensation

The mains electrical compensation should be automatic. The tube voltage shall be maintained at a value of within 1 kV of the selected value /kV for a mains voltage fluctuation of 7%

The leakage radiation from the tube housing should be less than 0.25 mGy in one hour (air-kerma) at one metre from the focal spot measured over an area not exceeding 100 cm

2

at the maximum tube rating.

Exposure control

The exposure switch shall initiate an exposure when pressure is applied and the exposure shall terminate if pressure is released.

The system should be Fitted with automatic exposure control. This should be reliable and consistent and maintain a variation of film density of less than 0.1 density units for the range of tube voltages and breast thicknesses of 2 to 6 cm. This may not be possible with

some

older equipment (manufactured prior to 1988).

The system should be fitted with a guard timer to terminate an exposure after a predefined time if the automatic exposure control mechanism has not functioned properly. The value of the predefined time should be documented by the manufacturer.

The manufacturer should clearly document whether the automatic exposure control mechanism can compensate for film reciprocity law failure.

The control panel shall clearly indicate when an exposure is taking place. The system should be provided with a post-exposure readout of mAs.

Focus to film distance

The focus to film distance should fall in the range of 55 - 65 cm.

Grids

The system should be provided with a secondary radiation grid with a grid exposure factor of less than three. The grid specifications (grid ratio line density, stationary or bucky, etc.) should be documented by the manufacturer.

Compression plate

A compression plate shall be provided on the system. The compression force should be greater than 150 N and less than 200 N.

Use of low attenuating materials

The table top grid and cassettes shall be made from low attenuating materials.

Breast dose

The entrance dose to the breast should not exceed 7 mGy. The mean glandular dose per radiograph should not exceed 3 mGy and shall not exceed 5 mGy.

Support table

The support table shall act as a primary beam absorber. There shall be no significant transmission of radiation through it.

6.

DENTAL X-RAY SYSTEMS

Focal spot

The position of the focal spot shall be marked on the tube housing.

The focal spot size should be measured throughout the working life of the tube to determine the extent of deterioration.

Leakage radiation"

The leakage radiation shall be less than 1 mGy in one hour (air-kerma) measured at I metre from the focal spot and over an area not exceeding 100 cm

2

for the maximum tube rating. For systems involving intra-oral films the leakage radiation should not exceed 0.25 mGy in one hour under the same measurement conditions.

Kilovoltage

The tube potential shall not be less than 50 kVp and the kVp setting on the control panel should be accurate to within 5

Filtration

The total filtration shall be at least 1. 5 mm Al for kVp < 70 kV and at least 2.5 mm Al for kVp ≥ 70kV. The inherent filtration should be marked on the tube housing and added filters should be marked with their value in Al equivalence.

Focus to skin distance

For systems employing intra-oral films the field spacer cone shall ensure a minimum focus to skin distance of

20 cm for kVp ≥ 60kV

and 18 cm for kVp < 60kV

Open ended cones should be used.

The field width at the patient end of the cone should be less than 6 cms and shall be less than 7 7cms.

Exposure control

An exposure shall be initiated only by applying pressure to the exposure switch. It shall also be possible to manually terminate an exposure by releasing the pressure on the switch.

When the mains voltage is switched on there should be a clear indication of this on the control panel.

The control panel shall be fitted with a light to indicate that an exposure is in progress.

Where preset exposure times are assigned in different dental examinations, as in anatomical timer, the preset time should be clearly documented by the manufacturer.

The preset exposure times shall be within 10% of those specified by the manufacturer. The same holds for manually selected exposure times.

Operator-protection

The cable length shall be sufficient to allow the operator stand at least 2 m from the x-ray tube and patient.

Radiation Output Consistency

For repeat exposures, the output shall be constant to within ; 10%.

Panoramic Units

Panoramic units should be fitted with a device to limit the minimum focus to skin distance to 15 cm.

On panoramic units the primary beam shall be collimated such that the size of the useful beam at the image receptor does not exceed by more than 2% of the source to image receptor distance, each dimension of the scanning slit.

Film storage and processing (all applications)

Storage and processing facilities shall be designed and located so that films are not exposed to more than 2 Gy prior to development.

7.

NUCLEAR MEDICINE INSTALLATIONS

Gamma camera performance parameters to be tested and documented

Integral and differential uniformity.

Integral resolution.

The system resolution at the collimator surface and at 10 cm depth in tissue equivalent material for each collimator.

The sensitivity of the system with each collimator over the range of energies for which that collimator is to be used.

Design and Performance standards

The gamma camera should have a mechanism for selecting `energy windows' appropriate to the range of radionuclides used in the installation. It should clearly indicate which energy window is operational and should have a simple system for verifying the accuracy of the window position.

The gamma camera should have a mechanism for terminating a study manually, by predefined counts and by predefined time. For systems that perform whole-body scanning or tomography there shall be an emergency stop mechanism.

The integral uniformity shall be 10%.

Shielding

The installation shall have a facility for preparing radiopharmaceutical injections with adequate protection for the operator and patient.

Syringe shields shall be available in the installation. If radiopharmaceutical injections have to be transported "within the installation then shielded transport boxes shall be available also.

Calibration

An Activity Calibrator/Dose Calibrator shall be used to quantify radioactive content of radiopharmaceutical injections. The Calibrator should be accurate to within 15% and should be linear with variation in activity. The calibrator shall be calibrated at least every year.

Radiological Hygiene

Washing facilities and appropriate decontamination equipment shall be provided in the installation.

Calibrated contamination monitoring equipment shall be available in the installation.

The installation should have a designated waiting area segregated from that used for other imaging modalities.

Radioactive waste

Suitable shielded storage facilities for waste material shall be available in the installation to enable compliance with local waste disposal requirements.

Given under the Official Seal of the Minister for Health and Children this 21st day of July 1998

Brian Cowen T.D.

MINISTER FOR HEALTH AND CHILDREN

EXPLANATORY NOTE

These regulations establish the criteria of acceptability to be met for radiological installations and nuclear medicine installations. The Regulations implement the provisions of EC Directive 84/466 Euratom of 3 September of 1984 laying down the basic measures for radiation protection of persons undergoing medical examination or treatment and to provide protection for workers and the general public.

4. Mechanical Performance (external beam equipment)

NB

In this section the isocentre is defined as the centre of the smallest sphere through which the axes of the radiation beams pass in all conditions.

(i) Accuracy of devices indicating the isocentre: 2 mm under all conditions.

(ii) Accuracy of devices indicating the axis of the beam: 2 mm regardless of any variation in either field size of SSD.

(iii) Accuracy of devices indicating distance along the axis: 2 mm over working range.

(iv) Accuracy of numerical indication of x-ray field size ≥ 2 mm up to 20cmx20cm field size and ≥ 1% for larger field sizes.

(v) At normal treatment distance (NTD)

Distance between edge of light field and 50% x-ray contour for field sizes 5 cm minimum dimension to the maximum available: 2 mm (this may increase to 3 mm at 1.5 NTD).

(vi) Distance between centre of radiation and light fields ≥ 2 mm at NTD and ≥ 3 mm at 1.5 NTD.

(vii) Couch movements.

(a) For a vertical movement of 20 cms, which includes NDT, the horizontal movement shall be ≥ 2 mm.

(b) Couch isocentre rotational movement.

The couch isocentre shall pass within 2 mm of the isocentre.

(c) Couch rotational movement.

Couch rotation axis shall be parallel to the couch isocentre rotation axis to

0.5°.

(d) Couch rigidity.

The couch top at the isocentre should not deflect vertically by more than 5 mm for a load increase of 30 kg to 135 kg at full couch extension.

(viii) Accuracy of scales

(a) Angular scales should indicate angles correct to 0.5°.

(b) Linear scales and readouts should read correct to 0.5 mms.

5. Dosimetry

In this section d

80

is the depth in centimetres of the 80% depth—dose value for a 10 cm x 10 cm field at the isocentric distance from the machine.

(i) Tolerance limits for x-rays

(a) energy < 10 MV d

80

= 8.5 cm

allowable deviation in d

80

: 2 mm

(b) energy > 10 MV d

80

: 8.5 cm

allowable deviation in d

80

: 3 m(c) variation with gantry angle and pulse rate frequency: 1 mm.

(ii) Tolerance limits for electrons

a) deviation in d

80

: 2 mm for energies up to 30 MeV (d

80

= 9 cm).

b) variation with gantry angle and pulse rate frequency: 1 mm.

(iii) Field uniformity (photons)

(i) Flatness limits are given in the following table

Field Size

Value of x along

Flatness

Major Axis

Diagonal

50 - 100 mm

10 mm

25 mn

1.06

101- 300 mm

0.1 x Field Size

0.2 x Field Size

1.06

+ 5 mm

301 - Max

30 mm

65 mm

1.10

Where x is the distance from the edge of the field and the flatness is defined as

Maximum dose within the beam

Minimum dose within the flattened area

(ii) Variation of flatness with gantry angle, prf

1.5

% (provided that flatness limits in (i) are not exceeded.

(iii) Field Symmetry

Greatest values of ratio of High Dose/Low Dose for each pair of points, each averaged over 10 mm profile line, within the flattened area.

Symmetry tolerance limits 1.03

(iv) Field Uniformity (electrons)

(a) Flatness specification

(i) At the depth-dose maximum, the distance between the 90% dose level and the geometrical beam edge is

along major axes = 10 mm

along diagonals = 20mm

and the maximum dose at any point relative to the actual axix is 1.03.

(ii) At the depth of the 90% depth-dose value, the corresponding distance between the 80% dose level and the geometrical beam edge is

along major axes = 15 mm

along diagonals = 30 mm

(b) Variation with gantry angle, p.r.f.

Allowable variation = 1.5% provided that the above flatness limits are not exceeded.

(c) Symmetry

Symmetry = Greatest Value of High Dose/Low dose for each pair of points each averaged over 10 mm of profile within the region bounded by the 90% dose values.

Symmetry Tolerance Limit = 1.03.

(v) X-ray contamination

(electrons only)

When measured 10 cm beyond the electron range, and expressed as a percentage of the maximum electron beam dose on the central axis of the beam, the x-ray Contamination shall not exceed the following values

898 Nominal Energy MeV

% Allowable Contamination

4

3.5

6

3.8

8

4.0

10

4.3

15

5.0

20

6.3

25

7.5

30

8.8

Depth-dose fall-off

Ratio of

Practical Range

: 1.7 for all Nominal Energies 4-30 MeV

d

80

Output

(i) Linearity—at least 10 exposures involving the same nominal dose shall be used to calculate the standard deviation in the measured values.

Limit .02 Gy or 2% which ever is the greater.

(ii) Reproductability—the nominal dose selected for the linearity test shall be divided into 5 equal portions. Measurements should be made of the total dose for all, five portions given sequentially.

The total reading shall be compared with the mean of the measured values found in (i) above.

Limit: .5 %

(iii) Variation with gantry angle, prf: difference between largest and smallest output < 3 %

6.

Dosimetry Equipment

(i) Dosimetry Calibration Equipment

Dosimeters used for patient dosimetry shall have a calibration which is traceable to a primary standard laboratory.

(ii) Radiation Survey Equipment

Dosimeters used for radiation surveys shall have a calibration which is traceable to at least a secondary standard laboratory.

2.

GENERAL RADIOGRAPHY

Warning lights/indicators

A clear signal shall be given on the control panel indicating when the x-ray tube is prepared to emit x-rays, and also when an exposure is taking place.

For permanently installed equipment there shall be a warning light at each entrance door to indicate when the x-ray tube is primed to emit radiation. This light shall be accompanied by a notice which indicates that entry is prohibited when the light is on.

Where two or more tubes are controlled from the same generator there should be a clear indication which tube is selected to produce x-rays.

Exposure Control

The exposure switch shall be designed so that an exposure may only be initiated by applying pressure to the switch and that the exposure may be terminated by removing such pressure.

For mobile systems the exposure switch shall allow the operator to stand at least 3 metres (m) from both the tube and the patient.

A key operated locking switch or equivalent should be provided for mobile equipment to prevent use by unauthorised personnel.

Focal spot

a. Indication

Every tube housing should have a mark indicating the position of the focal spot position.

b. Focal spot size

While no absolute standard is specified, focal spot size determinations should be carried out throughout the working life of a tube as part of the quality control procedures.

Leakage radiation

The leakage radiation from the tube housing shall be less that 1 mGy and should be less than 0. 1 mGy in one hour (air-kerma) at 1 m from the focal spot at the maximum tube rating. The measurement shall be made over an area not exceeding 100 cm

2

Filtration

The inherent filtration of the tube assembly should be marked on the housing.

The total filtration of the x-ray beam shall be at least 2.5 mm Al of which 1.5 mm shall be permanent. The added filters should be marked clearly with the Al equivalent thickness.

Kilovoltage

The tube voltage setting shall be clearly indicated on the control panel and shall be accurate to within:- 10% in the case of single phase units and 5% in the case of three phase units.

Mechanical Stability

The x-ray tube shall be securely fitted and correctly aligned within the tube housing. The tube housing shall be securely supported by mechanical means.

Capacitor Discharge Equipment

Capacitor discharge equipment shall be equipped with a

6. The provisions of these regulations shall be without prejudice to the rights and responsibilities of the Radiological Protection Institute of Ireland in relation to the custody, transportation, handling, holding, storage, use, manufacture, production, processing, importation, distribution, exportation, or other disposal of radioactive devices, nuclear devices or irradiating apparatus.

7. Radiological and nuclear medicine equipment, apparatus and installations being used for diagnostic or therapeutic purposes including general radiography, fluoroscopy, computerised tomography, mammography, dental radiography, nuclear medicine and radiotherapy shall comply with the criteria listed in the Schedule to these Regulations.

8. The competent authority in the state for the purpose of Article 3 of Council Directive 84/466/Euratom shall be the Minister for Health and Children.

SCHEDULE

1.

RADIOTHERAPHY

TREATMENT ROOMS

(i) Dose Control

Treatment Rooms (excluding wards where manually controlled sealed source treatment are carried out) shall be designed and shielded so that, from a consideration of work practices, use and occupancy factors, the following doses would not be exceeded. (For rooms used to house equipment operating above 10 MeV the neutron generated contribution to dose shall be included).

Category of Personnel

Design Level (millisieverts/year)

Exposed workers

5

Other workers employed in the hospital or clinic

.5

* In patients (per admission but exlcluding radiation doses associated with their medical care)

.5

Visitors temporarily occupying locations adjacent to treatment rooms

.5

All others

.05

* Shielding requirements for in patient wards should take account of such factors as typical length of hospital stay and the number of times the same patient might be admitted per year.

(TO BE READ IN CONJUNCTION WITH

S.I. No. 43 of 1991

)

(ii) Barriers & Interlocks

The entrance to the treatment room shall be fitted with a door or other barrier with an interlock which switches off the radiation source if entry is attempted. It shall not be possible to restart treatment other than from the control console.

(iii) Warning Signals & Notices

The entrance shall be fitted with one light which illuminates

when

the equipment is in a state of readiness to emit radiation and another which remains illuminated for the duration of the exposure.

These warning lights shall be accompanied by a notice which warns against entry when the warning light is on. The lights should also be wired, so that if a warning bulb fails, the equipment will not operate.

When treatment is taking place a visible warning signal is required within the treatment room. In the case of external beam treatment this shall be augmented by a continuous audible warning (in the case of x-ray unit and linear accelerators the noise produced by the equipment will normally suffice). In the case of isotope sources the in-room warning systems shall be energised by a gamma ray detector.

(iv) Emergency Equipment

A rod or other device to return a stuck source shall be located in a treatment room which houses external beam radioisotope equipment.

S.I. No. 250 of 1998.

EUROPEAN COMMUNITY (RADIOLOGICAL AND NUCLEAR MEDICINE INSTALLATIONS) REGULATIONS, 1998

The Minister for Health and Children in exercise of the powers conferred on him by

Section 3

of the

European Communities Act, 1972

(No. 27 of 1972), hereby makes the following regulations for the purpose of giving effect to Article 3 of Council Directive 84/466/ Euratom

(1)

laying down basic measures for the radiation protection of persons undergoing medical examination or treatment.

(1)

Official Journal of the European Communities, No. L265, 5/10/84 (Pages 1-3)