An efficient component of the redundancy calibration program to ensure equipment stability by assaying HDR Ir-192...

Brachytherapy (BT) treatments involving temporary high-dose rate (HDR) sources are extensively employed in clinical practice. Ensuring the consistency of all measurement equipment at the hospital level is crucial, requiring a robust redundancy and consistency program. This enables the institution to verify the stability of the dosimetry system over time.

To describe, justify, and analyze a component of the redundancy program of the calibration protocols followed by the Radiotherapy Department of the Hospital Universitari i Politècnic La Fe (València, Spain) during the last 10 years for the case of HDR BT as an additional component to ensure long term stability of the measurement equipment.

At the time the HDR BT source is replaced, its Air Kerma Strength (S_K) is measured. By comparing this value with the one obtained at the time of installation (corrected by decay), a clear determination of the stability of the measurement equipment can be performed.

Difference between S_K,vendor and S_K,hosp as a function of the measurement date is reported for a 10 years' period. All measurements are well within the ±3% tolerance level recommended in current international guidelines. Percentage differences of S_K,hosp values at the time of replacement compared to S_K,hosp ones at the time when the source was installed are within the ±0.5% range, reflecting oscillations around a null deviation.

The method proposed allows any hospital to ensure a redundancy component of the long-term stability of all equipment involved in BT measurements in a very simple and time efficient manner. Additionally, it enables the hospital to maintain a detailed log of historical differences, facilitating the identification and correction of potential systematic deviations over time.