Optimizing the TLD-100H Readout System under Various Radioactive I-131 Doses Via the Revised Taguchi Dynamic Quality Loss Function

The TLD-100H readout system performance under various radioactive I-131 exposure doses was optimized by four key factors via the revised Taguchi dynamic quality loss function. Taguchi dynamic analysis and the orthogonal array reorganizing the essential factors are crucial for the optimization of the thermoluminescent dosimeter (TLD) readout system given strict criteria of multiple irradiated environments and long-term exposure for calibrated TLDs. Accordingly, 96 TLD-100H chips were selected and randomly categorized into three batches with eight groups (four TLD chips in each group). Four factors, namely (1) initial temperature, (2) heating rate, (3) maximal temperature, and (4) TLD preheat time before reading were organized into eight combinations according to Taguchi suggestion, whereas each factor was preset at two levels. All 96 (3×8×4=96) chips were put in three concentric circles with 30, 60, and 90 cm radii for 48 h, surrounding the radioactive 150mCi (5.55×103MBq) I-131 capsule and exposed to the cumulative doses of 88.2, 18.6, and 8.6mSv for the respective radii, accordingly. The TLD readings obtained from each group were analyzed to derive the sensitivity, coincidence, and reproducibility, then those were reorganized to draw four fish-bone-plots for the optimization. The optimal option for the TLD readout system implied the combination of A1 (a 135°C initial temperature), B1 (a 10°C/s heating rate), C1 (a 240°C maximal temperature), and D2 (a 15s preheat time), which was further verified by the follow-up measurements. The dominant factors were A (initial temperature) and B (heating rate), whereas C (maximal temperature) and D (preheat time) were minor and provided negligible contributions to the system performance optimization.