The use of dosimetry in the treatment of differentiated thyroid cancer.

The standard treatment for the ablation of thyroid remnant tissue following surgery as well as for the treatment of iodine avid metastases in patients suffering from differentiated thyroid cancer (DTC) is therapy with radioactive iodine. Mostly fixed standard activities are used with the inherent risk of under- or overdosing the patient. Therefore, the rationale for using a dosimetry-based approach is to replace the conventional fixed activity regimen by a patient-tailored approach which allows the administered therapeutic activity to be increased while avoiding unwanted side effects. The purpose of this review was to describe the presently used dosimetric concepts: 1) the blood dosimetry approach (optimizing the "safety" aspect of the treatment); and 2) lesion-based dosimetry (optimizing the "efficacy" of the treatment) and their respective clinical findings. In addition, a simplified method for performing blood dosimetry and its application towards further enhancement of radioiodine therapies are introduced. Finally, a new concept for potentially determining patient-specific radiation sensitivity using blood dosimetry is introduced.