In vivo Dose Measurement in Cervical Cancer Brachytherapy Using Dysprosium-doped Calcium Sulfate Thermoluminescent Dosimeters: A Phantom Study
Prabhat Krishna Sharma, Saral Kumar Gupta, Devesh GuptaAbstract
Aims:
High-dose-rate (HDR) brachytherapy (BT) is an important part of the treatment of cervical cancer. Although there have been advances in three-dimensional image-guided treatment planning systems (TPSs), uncertainties in applicator positioning and anatomical variations can produce discrepancies in planned and delivered doses. This study aimed to evaluate the clinical feasibility and reliability of dysprosium-doped calcium sulfate (CaSO 4 :Dy) Teflon thermoluminescent dosimeters (TLDs) for independent dose verification in Co-60 HDR cervical BT.
Materials and Methods:
For calibration, the CaSO 4 :Dy Teflon TLD discs were held at a 5-cm depth in a phantom to closely mimic the conditions of dose measurements in a phantom. We specially constructed a phantom compatible with vaginal cylinders and Fletcher–Suit applicators to place TLDs at clinically significant sites. The measured doses were compared with TPS-calculated values by uncertainty analysis and statistical evaluation.
Results:
In-depth phantom measurements demonstrated that, for the same delivered dose, the response of CaSO
4
:Dy TLDs at 1-cm and 5-cm depth in the phantom differed by only about 4%. The TLD system demonstrated a combined uncertainty of 11.80% (
Conclusion:
The results confirm that with proper calibration, CaSO 4 :Dy Teflon TLD discs could also be a useful and trustworthy tool for independent dose verification in HDR BT. This approach can enhance routine quality assurance practices and improve confidence in dose delivery accuracy.