ESTRO 2024 - Abstract Book

S4755

Physics - Quality assurance and auditing

ESTRO 2024

In Fig. 2, (A) are shown the results of repeated tests to calculate the calibration coefficient curves based on the readings of only 5 array central points (Fig. 1, A). In the peripheral part of the array, these curves diverge greatly due to the “accumulation of errors” over “long” distance calculations. Curves in Fig. 2, (B) demonstrate the calculation of the calibration coefficients of detectors with f-function correction and the shape of this f-function. The agreement between the curves of several tests becomes significantly better after this correction. Fig. 2 (C) presents our results for detector calibration curves calculated by another method based on ratio of direct measurement of beam profiles using an ionization chamber in a water phantom and profile readings of array. We see the excellent overlap between these two methods (Fig. 2, B, C).

For comparison, the manufacturer's calibration curve (2017) is shown in Fig. 2 (D).

Figure 2. Calculated detectors calibration curves. A- for 5 measured points. B- for 7 measured points with f-correction. C- for water/array calculations. D- manufacturer's calibration curve (2017).

Conclusion:

The proposed method for recalibrating 2D array detectors does not require measurements in water, has good accuracy for nearby detectors, and does not require a long time (if the Excel file is prepared in advance).

Keywords: detector array, calibration, quality control