IS 13709: Medical electrical equipment - Dental X-ray equipment - Radiation safety

13 Pages·1993·1.4 MB·English

by  Bureau of Indian Standards

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in order to promote transparency and accountability in the working of every public authority,
and whereas the attached publication of the Bureau of Indian Standards is of particular interest
to the public, particularly disadvantaged communities and those engaged in the pursuit of
education and knowledge, the attached public safety standard is made available to promote the
timely dissemination of this information in an accurate manner to the public.
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“The Right to Information, The Right to Live” “Step Out From the Old to the New”
IS 13709 (1993): Medical electrical equipment - Dental
X-ray equipment - Radiation safety [MHD 19:
Immuno-Biological Diagnostic Kits]
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Satyanarayan Gangaram Pitroda
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“Knowledge is such a treasure which cannot be stolen”

Indian Standard
MEDICAL ELECTRICAL EQUIPMENT-
DENTAL X-RAY EQUIPMENT-
RADIATION SAFETY
UDC 621 386’1 : 616’314-073’75 : 614’876
t

0 BIS 1993
BUREAU OF INDIAN STANDARDS
MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARC
NEW DELH I 110002
March 1993 Price Group 3
Electromedical Equipment Sectional Committee, MHD 19
FOREWORD
This Indian Standard was adopted by the Bureau of Indian Standards, after the draft finalized by
the Electromedical Equipment Sectional Committee had been approved by the Medical Equipment
and Hospital Planning Division Council.
The widespread utilization of ionization radiation in medical diagnosis has brought in its wake the
need for exercising regulatory control and standardization for safety measures to ensure adequate
protection to the patient and the user. The Atomic Energy Regulatory Beard ( AERB ), Bombay,
is entrusted with the responsibility of developing and implementing appropriate regulatory measures
aimed at ensuring radiation safety.
This standard is intended to provide necessary guidance for the manufacturer and the user of dental
X-ray equipment to ensure that the patient and the occupational workers are not exposed to
radiation in excess of the operational limits specified under the Radiation Protection Rules, 1971.
The manufacturer shall ensure that the radiation protection measures in this equipment are
provided and maintained in conformity with these specifications by subjecting them to inspection
by the competent authority ( AERB, Bombay ).
For the purpose of deciding whether a particular requirement of this standard is complied with,
the final value, observed or calculated, expressing the result of a test or analysis, shall be rounded
off in accordance with IS 2 : 1960 ‘Rules for rounding off numerical values (revised)‘. The
number of significant places retained in the rounded off value should be the same as that of the
specified value in this standard.
IS 13709 : 1993
Indian Standard
MEDICAL ELECTRICAL EQUIPMENT -
DENTAL X-RAY EQUIPMENT -
RADIATION SAFETY
1 SCOPE 3.5 Automatic Exposure Control
1.1 This standard specifies the measures for A device which automatically controls one or I
radiation safety of dental X-ray equipment used more technique factors ( see 3.26) to obtain at a
in medical practice by persons having adequate pre-selected location(s), a required quantity of
knowledge and understanding of radiation hazards radiation.
and protection.
3.6 Beam Axis
2 REFERENCES
A line from the source through the centres of the
X-ray fields.
2.1 The following Indian Standards are necessary
adjuncts to this standard:
3.7 Beam Limiting Device
IS No. Title
A device which provides a means to restrict the
6567 : 1972 Radiation protection for an
dimensions of the useful beam.
X-ray tube in a protective
tube housing, operating
3.8 Control Panel
between 10 kV and 400 kV
7620 Diagnostic medical X-ray That part of the X-ray control, upon which are
(Part 1): 1986 equipment: Part 1 General mounted the switches, knobs, push-buttons and
and safety requirements other hardwares necessary for manually setting
(jirst revision > the technique factors.
7620 Medical electrical equipment 3.9 Dental Cone
(Part 3) : 1991 -Diagnostic X-ray equip-
ment: Part 3 Radiation safety A device used in dental radiology to ensure a
requirements required focal spot-to-skin distance and to
recognize the direction of the axis of the useful
3 TERMINOLOGY beam. A dental cone may include a beam
limiting device and protective shielding.
3.0 For the purpose of this s ta ndard, the follow-
ing definitions shall apply. 3.10 Dental Source Assembly
3.1 Accessible Surface The tube housing assembly consisting of tube,
high voltage and/or filament transformers,
The external surface of the X-ray tube enclosure permanent filtration and the beam limiting device,
or housing provided by the manufacturer.
3.11 Dental X-Ray Equipment ( henceforth termed
‘Equipment’ )
3.2 Aluminium Equivaient
X-ray equipment designed for radiological exami-
In respect of a material under specified conditions,
nation of the mouth, teeth and jaws for the
the thickness of aluminium that under those
purpose of diagnosis or visualization.
conditions, affords the same attenuation as that
material and is expressed in mm Al.
3.12 Exposure
3.3 Assembler The quotient dQ/dm where dQ is the absolute
value of the total charge of the ions of one sign
Any person engaged in the business of assem- produced in air when all the electrons ( negatrors
bling, replacing of installing one or more and positrons ) liberated by photons in a volume
components into an X-ray equipment or a element of air having mass dm are completely
sub-system. stopped in air. In case of leakage radiation, the
value is expressed in terms of air kerma. The
3.4 Attenuation SI unit of air kerma is Gray (Gy ) or milligray
( mGy). Air kerma of one Gray is equal to
A decrease in radiation intensity caused by energy absorption of 1 J/kg of air exposed to
absorption and scattering in a medium. radiation.

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IS 13709:1993
3.13 Filter 3.23 Rated Tube Current
A layer of radiation attenuating material incor- The maximum allowable tube current.
porated in the tube housing to preferentially
absorb the less penetrating components of the 3.24 Rated Output Voltage
useful beam. Permanent filter is the lilter which
is an integral part of the tube housing and which The maximum allowable peak potential at the
cannot be removed by the user unlike the added output terminals of the X-ray tube.
filter.
3.25 Source
3.14 Half-Value Layer ( HVL )
The focal spot of the X-ray tube.
The thickness of specified material which when
introduced into the path of a beam of 3.26 Technique Factors
radiation attenuates the beam of radiation to
The technique factors are the conditions 01’
one-half of its original value.
operation. These are specified as follows:
3.15 Image Receptor
a) For capacitor energy storage equipment,
Any device, such as, fluorescent screen or radio- peak tube potential in kV and quantity 01
graphic film which converts incident X-ray charge in mAs;
photons either into a visible image or into
b) For field emission equipment rated for
another form which can be further transformed
pulsed operation, peak tube potential in
into a visible image.
kV and number of X-ray pulses; and
3.16 Intensifying Screen cl For all other equipment, peak tube poten-
tial in kV and either tube current in mA
A layer of material used in direct radiography to
and exposure time in second or the product
intensify the: action of incident X-radiation on
of the tube current and exposure time in
radiog.raphic film.
mAs.
3.17 Lead Equivalence
3.27 Useful Beam
It is the thickness of lead which under specified
The part of the emergent radiation from an X-ray
conditions of irradiation, affords the same
tube housing which is capable of being used for
attenuation as the material under consideration.
the purpose for which the X-ray equipment is
intended.
3.18 Leakage Radiation
Radiation emanating from the dental X-ray 3.28 X-Ray Control
source assembly other than (a) the useful beam
A device which controls input power to the
and (b) the radiation produced when the exposure
X-ray high voltage generator and/or the X-ray
switch or timer is not activated.
tube. It includes equipment which controls the

technique factors of an X-ray exposure.
3.19 Mobile Equipment
3.29 X-Ray Tube ( henceforth termed ‘Tube’ )
Transportable equipment designed to be moved
from a location to another between periods of Any electron tube which is designed for the
use on its own wheels or similar means of conversion of electrical energy into X-ray energy.
support.
4 MARKING
3.20 Portable Equipment
4.1 All components except high voltage generators
The equipment designed to be hand carried from
contained within the tube housings and beam
one location to another between periods of use.
limiting devices which are integral parts of tube
housing shall be permanently inscribed or affixed
3.21 Primary Protective Barrier
thereon, the model number and serial number of
The material excluding filters placed in the useful the product which shall be clearly visible. Every
beam and incorporated into the equipment by dental X-ray equipment shall bear the following
the manufacturers to reduce the radiation marking on the external surface of the main
exposures to the equipment/personnel during X-ray control panel:
operation.
a) the X-radiation warning symbol as given in
Fig. 1.
3.22 Radiation Protection
b) A readily discernible and clearly visible
Measures taken to minimize exposure to patients, permanent mark or label indicating
medical and paramedical staff and general public
so as to limit the biological consequences of 1) the source of manufacture,
ionizing radiation to acceptable levels. 2) the serial number,

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IS 13709: 1993
CAUTION X-RAY >
FIG. 1 X-RADIATION WARNING SIGN
3) the type designation, b) the following written information from the
manufacturer with respect to the
4) rated voltage,
equipment:
5) maximum instantaneous rating ( mA ),
1) Maximum power requirements or
6) supply voltage and frequency, maximum line current, and
7) year of manufacture, and 2) Nominal focal spot size of the
8) the country of manufacture. X-ray tube target and the method of its
determination.
c) With respect to X-ray tube,
1) indication of the source of manufacture, 5.2 The following information shall he supplied
with each equipment:
2) the model designation,
a) General description of the equipment,
3) the serial number,
4) year of manufacture, and b) Characteristics of the generator,
5) the country of manufacture.
c) Details of controls, and

NOTE - The replacement of an X-ray tube in a
previously manufactured tube ho u sing assen;bly d) Details of other accessories.
shall be subject to the provisions of Ihe above
paragraph. The assembler shall remove, cover. 5.3 Each dental X-ray equipment shall be
or deface any previously affixed inscriptions.
provided with the following details:
tags or lab:is which are no longer applicable.
a) Manual containing operating instructions,
d) The location of the focal spot along the
X-ray beam axis within 1j1.4 mm, and b) Maintenance/service manual,
e) The minimum permanent filtration in the
c) Spare parts list, and
useful beam provided by the assembly
expressed as millimetres of aluminium d) Circuit diagram.
equivalent at a specified peak tube
potential. 6 RADIATION SAFETY
4.2 Cones and diaphragms shall be marked with 6.1 Every dental X-ray machine shall be designed
the appropriate field size and distance of source and constructed as specified in IS 7620 (Part 1 ) :
to X-ray field plane for which the field size is 1986.
referred to.
6.1.1 All components used in the manufacture/
5 ACCOMPANYING DOCUMENTS
assembly of dental X-ray equipment/accessories
except those specified in this standard shall
5.1 Every dental X-ray equipment shall be
conform to the relevant Indian Standard
provided with:
specifications on the design, construction and
a) installation and maintenance instructions performonce.
supplied by the manufacturer of the device,
that if followed by trained and experienced 6.2 Every dental X-ray tube shall be securely
personnel, will provide adequate radiation fixed and correctly aligned within the tube
safety; and housing.

3
IS 13709: 1993
6.2.1 The manufacturer of X-ray tube housing 4 Where the device is battery operated, a
assembly shall specify the source to beam limiting visual indicator that shows whether the
device distance and maintaiu this for the tube battery is adequately charged for proper
housing assembly within a tolerance of &3 mm. operation.
6.3 The X-ray tube housing shall maintain its
6.5.3 An exposure switch ( deadman type ) of a
required exposure position without drift or
vibration during operation. kind that requires continuous pressure by the
operator to complete the circuit and where the
switch is on a cable, the cable shall be of such a
6.4 ;Dental X-ray equipment shall, where more
than one X-ray tube is controlled by one control length as to enable the operator to stand at
least 3 m away from the X-ray source.
panel, be designed to include the following safety
features:
6.5.4 Radiation filters that:
a) An interlock such that it is not possible to
energize more than one X-ray tube at the
a) are permanently affixed to the exit port of
same time.
the X-ray tube housing, or beam limiting
b) A readly visible indicator that shows when device, or both; and
that tube is connected and is ready to be
energized on each X-ray tube housing or in b) provide total attenuation of the useful
close proximity to each housing so as to be beam at least equivalent to that afforded
clearly distinguishable from the position of by:
the housing.
1) 2’5 mm Al for machines designed to
c) A readily visible indicator showing which operate with X-ray tube potential above
X-ray tubes are connected and ready to be 70 kV ( peak ), and
energized at the X-ray machine control
panel. 2) 1’5 mm AI for machines designed to
operate with X-ray tube potential at or
6.5 Every dental X-ray machine shall be designed below 70 kV ( peak ).
and constructed to include the following features:
6.5.1 The voltage of the X-ray tube shall be 6.5.5 Keyed filter interlock switches or other
maintained at its selected value to within 3 positive means to ensure that the necessary added
kilovolts when the line voltages supply, having an filtration is in place in any tube housing assembly
impedance equivalent to 1 ohm, varies by i 10 that:
percent of its nominal value. This requirement
shall be verified at the manufacturer’s premises. a) has permanent inherent filtration of 0’5 mm
or less aluminium equivalence, and
6.5.2 The control panel with following features:
b) is designed to be operated with added
a) A separate warning light in clear view of filtration.

the operator that respectively indicates

1) when the control panel is energized and
6.5.6 A timer such that:
the device is ready to produce X-rays,
and
a) termination of an exposure shall not cause
2) when the X-rays are produced. automatic resetting of the timer to its
original setting,
b) Where the device has adjustable technique
factors, electrical meters or other indicators b) an exposure cannot be initiated with the
that enable the following factors or any timer set at zero or its ‘OFF’ position,
combination thereof to be indicated before
the exposure is initiated: 4 repeat exposures cannot be initiated with
recycling timers without the release of
1) Operating tube voltage in kilovolts,
exposure switch to reset timer,
2) Tube current in milliamperes, and
4 the production of X-rays is automatically
3) The exposure time in seconds.
terminated after
c>
Where the device has non-adjustable
1) a preset time interval when the equip-
technique factors, permanently fixed marks
ment is operating in a fixed milliamper-
or label or electrical meters or other
age mode, and
indicators that enable at specific source to
image receptor distance, the following 2) a preset milliampere-second when the
factors or any combination thereof to be equipment is operating in a variable
indicated before the exposure is initiated: milliamperage mode or variable time
1) Operating tube potential in kilovolts, mode or both,
2) Tube current in milliamperes, and 4 the range of exposure time shall not exceed
3) The exposure time in seconds. 5 seconds.
4
IS 13709:1993
7 BEAM LIMITATION AND PROTECTION 7.2.3 Beam limiting devices shall provide at least
AGAINST PRIMARY AND STRAY the same degree of attenuation of unwanted
RADIATION radiation as required of the X-ray tube housing
and limit the size of the useful beam:
7.1 Leakage
a) at image receptor of equipment designed
The leakage radiation at a distance of 1 m in for panoramic examination to size that does
maximum direction from the focal spot of the not exceed by more than two percent of
X-ray tube does not exceed 100 milliroentgen the source-to-image receptor distance for
( mR ) or 1 mGy in one hour under any exposure each dimension of the scanning slit;
conditions within the rated limits of the X-ray
b) to the size of the image receptor or a
tube. While measuring the leakage radiation,
diameter of 300 mm, whichever is smaller,
useful beam shall be completely blocked by at
at a distance of 1’5 m from the focal spot
least 10 HVL of lead.
in equipment that is designed for cephalo-
metric examination; and
7.1.1 Compliance for requirement in 7.1 shall be
determined by measurements averaged over an
C) to a maximum linear dimension of 70 mm
area of 100 cm2 with no linear dimension greater
at the end of the localizing cone or beam
than 20 cm ( see 5 of IS 6567 : 1972 ).
limiting appliances for all other equipment.
7.2 Beam Limiting Devices
8 REQUIREMENTS FOR DENTAL
RADIOGRAPHIC EQUIPMENT
7.2.1 These shall be provided to limit the useful
beam to the area of clinical interest. The beam
8.1 For dental X-ray examination, it shall be
limiting devices in combination with the tube
ensured that the prescribed dose equivalent limits
housing shall comply with the requirements for
for the operator are not exceeded.
leakage radiation specified in 7.1.
In the accompanying documents (see 5 ),
7.2.2 Dental X-ray assemblies for use with intra- attention shall be drawn to the necessity for
oral film shall be provided with dental cones gonad shielding of the patient during dental
ensuring the minimum focal spot-to-skin distance examinations, particularly if the direction of the
required below and with permanently included useful beam or expected stray radiation requires
fixed size diaphragms. For the use of inter- additional protective shieldings.
changeable dental cones, provision shall be made
that a diaphragm is in place limiting the useful 8.2 The control circuit of equipment specially
beam so as not to exceed the maximum permitted designed for dental radiography ( see 8.3, 8.4
size. and 8.5) shall be so constructed as not to allow
the use of the equipment for fluoroscopy. It
The minimum focal spot-to-skin distance ensured shall not be possible to make repeat exposures
by means of dental cone, shall be as low as the without release of the exposure switch.
values given below:

8.3 The equipment specially designed for dental
Maximum Tube Potential M inimum Focal
radiography on film inside the mouth shall comply
kV Spot-to-Skin
with the following requirements:
Distance
mm a) The exposure shall be controlled solely by
50 to 60 100 means of a deadman switch so constructed
that exposure is maintained only by con-
Above 60 and up to and 200
tinuously activating the switch and a timing
including 75
device. The timing deviec shall be designed
Above 75 300 to terminate any uninterrupted period of
exposure after a preset duration in a range
7.2.2.1 The cones for dental radiography on intra- which does not exceed 5 seconds.
oral film shall meet the following requirements:
b) Dental X-ray assemblies for use with intra-
a>
The diameters of the useful beam at the oral films shall be provided with the beam
distal end of the dental cone shall not limiting cones. The cone shall provide the
exceed 75 mm. same degree of protective shielding as is
required for X-ray tube assembly.
b) For cylindrical and divergent dental cones,
with and without open end, the maximum cl Provision shall be made to recognize the
size of the useful beam shall comply with position of focal spot and the direction of
the area of the dental cone at the distal the axis of the useful beam.
end. d) In the accompanying documents (see 5 ).
c) Interchangeable cones with permanently attention shall be drawn to the necessity of
included fixed diaphragm shall be marked providing additional protective shielding
with the diameter of the cross-section of for the operator, such as, protective screens
the useful beam at the distal end of the and aprons for conditions of high work
dental cone. load.

5