YY/T 1733-2020Radiation sterilization of medical devices—Guide for dose mapping in irradiation processing facilities (English PDF)

3.2 A graph showing the response function of the dose measurement system

Note. The calibration curve represents the relationship between the indicated quantity and the corresponding measured value. In radiation processing standards, the dosimeter response is usually used as an indicator.

3.4 Dose zone

The area or discrete points of the equivalent absorbed dose in the processing load, the difference between the equivalent absorbed dose is measured in the irradiation process and the absorbed dose Within the range of statistical uncertainty.

3.11 Simulated product material

A homogeneous material with known radiation absorption and scattering characteristics used to establish the characteristics of the irradiation process. The characteristics of the irradiation process include scanning uniformity, depth Degree of dose distribution, production efficiency and dose reproducibility.

4.1 Overview

Installation qualification and calibration of the dose measurement system should be performed before the dose distribution test.

4.2 Installation appraisal

4.2.1 Before implementing the dose distribution test for the operation qualification and performance qualification of the irradiation device, it should be confirmed that the installation qualification has been completed.

4.2.2 For electron beam and X-ray irradiation devices, the installation qualification includes the beam characteristics (electron energy, average beam current, and when applicable, Scan width and scan uniformity) dosimetry test.

4.2.3 For gamma irradiation devices, it is not necessary to conduct dosimetry tests during the installation qualification period, but the activity and location of each radioactive source should be Confirm and record.

4.3 Calibration of the dose measurement system

4.3.1 Before use, the dose measurement system should be calibrated. The dose measurement system includes dosimeter measuring instruments and related reference Standards and procedures for use. The calibration is carried out in accordance with the procedure document that stipulates the calibration process and quality requirements. Refer to GB/T 16640 for the calibration method.

4.3.2 For the calibration of the instrument and equipment and the performance verification of the instrument and equipment between the two calibrations, follow GB/T 16640 and/or the operation of the instrument and equipment. Make a manual.

5.1 Run the qualification dose distribution test

5.1.1 In accordance with the requirements of GB 18280.1, implement the dose distribution test of the irradiation device to determine the absorbed dose distribution and the re-absorbed dose The characteristics of the irradiation device such as availability. It should be tested in accordance with formal verification procedures and should cover the expected operating range of the irradiated product.

5.1.2 Place the dosimeter in multiple processing loads from the reference material to the upper limit of the design volume of the irradiation container, and perform the dose of the irradiation device.

Quantity distribution test. The number of processing loads should be large enough (3 or more) to determine the range of dose variation. Changes in operating parameters can affect For dose distribution irradiating devices, the operating parameters for performing dose distribution tests should cover the operating limits of the irradiated products.

5.1.2.1 For gamma or X-ray irradiation devices, the material density should be within the applicable density range of the irradiation device. When processing multiple densities At least two density dose distribution tests should be performed, using materials close to the lower limit and upper limit of the irradiating device's use density range respectively.

Line to evaluate the impact of density on the distribution and magnitude of absorbed dose. Users can consider increasing the dose distribution test of intermediate density to obtain better Multi-performance information.

5.1.2.2 For electron beam irradiation devices, one or more reference materials within the expected irradiated material density range shall be used for dose analysis. Cloth test.

5.1.2.3 Determine the absorbed dose distribution in the processing load for each product irradiation path and each set of process parameters in the radiation field.

Note. Other ways to affect the absorbed dose distribution in a given processing load include. single-sided or double-sided irradiation in electron beam and X-ray devices, and gamma irradiation devices Use multiple source racks or change the position of the source racks.

5.1.2.4 For each processing load, arrange a sufficient number of dosimeters to determine the absorbed dose distribution. Band-shaped dosimeter can be used Spatial resolution of high dose distribution. The layout diagram of the dosimeter is shown in Figure 1.

5.1.2.5 Measure the dose at the same position in three or more repeated processing loads to determine the irradiation path of each product and each group of processing parameters The measured absorbed dose and the variation range of the absorbed dose distribution.

a) For processing loads that pass through the radiation field, there should be a sufficient number of similar loads before and after the processing and loading of the dose distribution test.

Workloading minimizes the difference in absorbed dose distribution during processing loading.

b) Depending on the design of the irradiation device, additional dose distribution studies may be needed to determine the structure and loading of the processing during processing.

The change of its density affects the dose and dose distribution. The effect of density change on dose and dose distribution can be determined by the following Evaluation method. continuous irradiation of two processing loads of different densities, the last processing load of the first density and the second Do the dose distribution test for the first processing load of one density, and compare these results with the homogeneous density dose distribution described in 5.1.2.5a) Compare the results obtained by the cloth test.

c) If the results of the running qualification measurement show that the structure of the processing load and its density change may affect the dose and dose distribution If the product is affected, the impact on the actual product radiation processing should be evaluated during the performance appraisal, see 5.2.5.

5.1.2.6 After irradiation, retrieve and measure the response of each dosimeter, and evaluate the data according to the established procedures.

5.1.3 If there is a change in the irradiation device that affects the absorbed dose or the absorbed dose distribution, it should be assessed whether the dose distribution needs to be redone test.

Note. GB 18280.1 provides additional guidance on the change of irradiation equipment and recommended change identification activities.

5.1.4 Use a mathematical model to determine the position of the dosimeter for the dose distribution test or predict the result of the dose distribution test.

Note. See ASTM E2232-16.

5.2 Performance appraisal dose distribution test

5.2.1 Perform dose distribution tests on specific products and loading forms to determine the expected dose distribution during daily processing.

International products or analog products with similar density, distribution and packaging methods to actual products.

5.2.2 If the routine monitoring position is used for process monitoring, the maximum dose, the minimum dose and the dose at the routine monitoring position should be established. Relationship.