Invited Lecture 1.3

Abstract

Voxel-based dosimetry with 177Lu-PSMA (prostate-specific membrane antigen) refers to a method used in nuclear medicine for the precise calculation and measurement of radiation dose distribution within the body. Once the patient has received 177Lu-PSMA therapy, post-therapy imaging is conducted at different time points to assess the distribution of the radiopharmaceutical and calculate the absorbed radiation dose to the tumour and/or the organ at risks (OARs) such as kidneys, liver, salivary glands or bone marrow. This is where voxel-based dosimetry comes into play. Voxel-based dosimetry involves dividing the images into small volume elements called voxels. These voxels represent small 3D units within the patient's body. The activity within each voxel is quantified based on the intensity of the radiotracer signal. By tracking the distribution and decay of 177Lu-PSMA within these voxels over time, the absorbed dose to each voxel and corresponding OARs or tumors can be calculated. Consequently, the dosimetry results provide valuable information for clinicians to optimize treatment planning and assess the efficacy and potential toxicity of the therapy. This information helps in adjusting the treatment parameters for individual patients, such as the administered activity and the number of treatment cycles. Voxel-based dosimetry offers advantages over traditional methods by providing a more accurate and personalized assessment of radiation dose distribution, which can ultimately lead to better treatment outcomes and reduced side effects for patients undergoing 177Lu-PSMA therapy.​