Transitioning from OSLDs to TLDs for in-Vivo Dosimetry in Total Skin Electron Therapy: A Clinical Perspective

Abstract

Purpose: Mycosis fungoides, a type of non-Hodgkin lymphoma that affects the skin, is effectively treated with Total Skin Electron Therapy (TSET). Previously, we used optically stimulated luminescence dosimeters (OSLD) for in-vivo dosimetry (IVD) during TSET. However, following an FDA recall of the OSLD nanodots, we transitioned to thermoluminescent dosimeters (TLD) for IVD. This study aims to compare TLD and OSLD measurements in TSET treatment and assess the feasibility of using TLD measurements in institutions lacking a TLD reader.

Methods: A patient with mycosis fungoides underwent TSET treatment following a modified Stanford technique. The prescription dose was 16Gy in 8-fractions delivered to the depth of 8mm using the high dose-rate electron (6MeV) beam. The patient was positioned at 450cm from the radiation source and employed an acrylic attenuator. TLDs (TLD100) were obtained from the University of Wisconsin-Madison Radiation Calibration Laboratory (UWRCL). TLDs and OSLDs were calibrated at dmax. Both dosimeters underwent MU linearity and percentage depth dose verification. For IVD, TLDs and OSLDs were placed adjacent to each other at fourteen anatomical sites during the first fraction. TLDs were subsequently sent to UWRCL for reading, while OSLDs were read using the microSTARii reader (Landauer, USA). The IVD results were then compared with the prescribed dose.

Results: The TLD measurements exhibited an average variation of (-2.08±4.37)% from the prescribed dose, ranging between -10.57% and 5.50%. This indicates a relatively uniform dose distribution across the body surface. In comparison, OSLD measurements showed a larger average variation of (-4.93±4.72)%, ranging from -10.43% to 4.16%.

Conclusion: Our measurements suggest that TLDs offer superior dosimetric accuracy compared to OSLDs in TSET procedures. Utilizing TLDs for IVD is feasible and reliable, even without direct access to a TLD reader, supporting their broader adoption for IVD in clinical settings.