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Section 11: Visual Indicators

All Controls Clearly Identified

Standard

Section 9 (2a) of HARP Regulation states:

"Every diagnostic x-ray machine shall be so constructed that all control, meters, lights or other indicators on the machine are readily recognizable and clearly identifiable as to function;"

Evaluation

Clearly identified means that the indicator must be labeled as to function. For example, "table photo timer" as opposed to an unidentified button.

 

Technique Factors Indicated

Standard

Section 9 (2e and f) of the HARP Regulation states:

"Every diagnostic x-ray machine shall be so constructed that,

(e) where the machine has individual technique factors that are either fixed or can be selected manually by the operator, there are electrical meters, controls or other indicators to enable the x-ray operator to determine those selected technique factors before the patient is irradiated,'

(f) where the x-ray machine is used in the radiographic mode and has automatically controlled exposure or automatically related exposure selection or falling load, there is an electrical meter, control or other indicator that enables the x-ray operator to determine the kilovoltage before the patient is irradiated,'"

 

Evaluation

The following are acceptable for fixed or manual indicators:

1. Peak tube kilovoltage

Meter, label or LED readout

2. Tube current

Meter, label or LED readout

3. Exposure time

Label or LED readout

4. Added filtration

If permanent, a label is not required. However, if removable or changeable then the filter or the dial must be labelled with the filtration value. Also if the amount of filtration is adjusted at all, a technique chart or written procedure must be available to the operator to ensure correct use of filtration.

5. Source to image distance

If more than 2 SIDs are used there must be a scale, in centimetres or inches, which indicates the SID to an accuracy of+ 5%. For those operators using one or two SIDs, a mark on the track stating the actual distance is acceptable, as long as it is within + 5% of the actual distance. Measure the accuracy of the indicated distances using a measuring tape. Measure the actual distance from the target of the x-ray tube to the image receptor.

6. Kilovoltage known

Observe whether kilovoltage is known before an exposure is made.

7. Time selections

Observe whether the time selections are clearly identifiable.

 

Control Warning Sign

Standard

Section 9 (la & b) of the HARP Regulation states:

"Every diagnostic x-ray machine shall bear either on the external surface of the main x-ray control panel of at the exposure switch location a warning sign that indicates that,

(a) unauthorized use is prohibited,' and

(b) hazardous radiation is emitted when the x-ray machine is activated"

 

Evaluation

Any exposure switch, remote or otherwise, in a location that is accessible to the public must bear a warning sign.

 

Line "ON" and X-ray "ON" Indicators

Standard

Section 9 (2d) of the HARP Regulation states:

"Every diagnostic x-ray machine shall be so constructed that,

(d) there are recognizable warning lights or other indicators that indicate,

(i) when the machine is energized and is ready to produce x-rays, and

(ii) when the x-rays are produced,'

Evaluation

The following are acceptable indicators that the machine is energized:

  1. A meter which reads when the machine is switched on. For example, line compensator, mA meter.
  2. Line-on light indicator.
  3. On/off switch provided that both positions are clearly labelled.

The following are acceptable indicators that x-rays are being produced:

  1. An audible signal.
  2. A light indicator visible to the operator
  3. An mA(s) meter reading.

 

Line Voltage Indicator

Standard

A line voltage compensator on a radiographic or dental unit must adjust for variation in the incoming voltage.

When a line voltage compensator is manually adjustable, it must be used correctly. The correct reading on the compensating meter is determined by the manufacturer and may be indicated by a green or black line or a volt reading.

 

Battery Condition Indicator

Standard

Section 9 (2g) of the HARP Regulation states:

"Every diagnostic x-ray machine shall be so constructed that,

(g) where the x-ray machine is battery powered, there is a visual indicator that shows whether the battery is charged for proper operation;"

Equipment

There must be a label stating that the machine is not to be used unless it is charged for proper operation, if it is possible to expose the unit below the safe operating range.

Procedure

(for use if there is an exposure interlock for low battery condition)

  1. Place the fluoroscopy wand or dosemeter detector on a flat surface.
  2. Ensure that the battery is below the proper operating level. This will generally be the situation when testing of mobile x-ray machines has been completed.
  3. Position the x-ray tube in close proximity above the test instrument, centering the beam to the instrument. Collimate to just larger than the test instrument.
  4. If the fluoroscopy wand is used, darken the room.
  5. Select a low kVp, low mAs technique.
  6. Expose and observe whether there is any fluorescence of the wand or a reading on the dosemeter.

 

Multiple Tube Indicators

Standard

Section 9 (2h & i) of the HARP Regulation states:

"Every diagnostic x-ray machine shall be so constructed that,

(h) it is not possible to energize more than one x-ray tube at the same time, and

(i) where there are two x-ray tubes, there is a visible indication of which x-ray tube is selected and ready to be activated at the control panel."

 

X-ray Tube Position Locks

Standard

Section 9(2c) of the HARP Regulation states:

"Every diagnostic x-ray machine shall be so constructed that the x-ray tube housing maintains its required exposure position without significant drifting, tipping or vibration so as to affect the quality of the image;"

 

Exposure Switch Cord Length

Standard

Section 10(l a & b) of the HARP Regulation states:

"Every exposure switch on an x-ray machine shall,

(a) be so located that it cannot be conveniently operated outside a shielded area, and

(b) where it is part of a mobile machine, be equipped with a cable at least three metres in length."