Calibration of Radiological Measurement Devices Using X-Rays: Objectives and Scope

Calibration of radiation measuring devices with X-rays: Purpose and Scope

In Sub-item 1, Sub-item 2, Section I of Appendix III.2 issued with Circular 08/2022/TT-BKHCN (effective from July 22, 2022), the purpose and scope of the calibration of radiation measuring devices with X-rays are specified as follows:

1. Purpose

This procedure regulates the calibration activities of radiation measuring devices with X-rays to determine the device's indicators as well as measurement functions (measured quantities) correctly under calibration conditions.

2. Scope and objects of application

This procedure applies to organizations and individuals involved in the service of calibrating radiation measuring devices with X-rays; state management agencies and other related organizations and individuals.

What is the content of the calibration procedure for radiation measuring devices with X-rays?

According to Sub-item 3, Section I of Appendix III.2 issued with Circular 08/2022/TT-BKHCN (effective from July 22, 2022), the calibration of radiation measuring devices with X-rays follows the procedure as follows:

3.1. Diagram

3.2. Explanation

Step 1: Calibration preparation

- Use a handheld dosimeter (abbreviated as PSM) throughout the process.

- Wear a personal dosimeter to assess personal dose equivalents during calibration.

- Turn on the air conditioning and dehumidification system to ensure the environmental conditions in the calibration room.

- Turn on the control unit, computer, laser system, and camera to stabilize the system.

- Check the parameters of the devices surveying the dose rate around the calibration area to ensure background levels when conducting calibration. Record the measured environmental dose rate value.

- Disinfect, wear gloves, and a mask before proceeding with subsequent tasks.

- Turn on the PSM to be calibrated, clean, and replace the battery if necessary. Wait for the PSM to stabilize. In the meantime, record the information about the PSM, including:

+ The name of the user unit.

+ Name of the PSM to be calibrated, model, serial (record full parameters of the detector and accompanying display unit).

+ Quantity the PSM uses for calibration, working measurement ranges of the device.

+ Record the calibrated background measurement value of the PSM.

Step 2: Conduct calibration

- Operate the X-ray generator and place corresponding filters with X-ray qualities according to ISO 4037 with different qualities.

- Determine the effective point of the PSM based on the manufacturer's technical documentation.

- Identify the standard distance between the X-ray emitting focal point and the effective point of the probe to get the conventional true value for the quantity to be calibrated for the PSM.

- Use the laser system, calibration table, and level ruler to place the effective point of the probe at the central axis of the radiation field according to the vertical laser, at a determined distance according to the horizontal laser.

- Position, adjust the camera so that the PSM indicator is clearly visible, and ensure the camera is outside the direct radiation area.

- Close the calibration room door after ensuring no one remains inside, verify and ensure the interlock system functions properly.

- Perform irradiation and record the value indicated on the PSM into the experiment book according to the available form.

- Conclude irradiation and conduct a preliminary assessment of the obtained results.

Step 3: Data processing and result evaluation

Determine the calibration factor of the PSM and report the recorded data.

Step 4: Calibration result report

Summarize and report calibration results in writing.

Regards!