Abstract ID: 376 Dosimetry in Radioactive Iodine Treatment of Metastatic Differentiated Thyroid Cancer

Abstract

Purpose The aim of the presentation is to investigate the opportunity of performing dosimetry in Radioactive Iodine Treatment of Metastatic Differentiated Thyroid Cancer (RAIT). Methods RAIT has been established in the management of patients with metastatic thyroid cancer therapy. Since its first use, the optimal activity to be administered has been under discussion. The activity can be determined using an empiric approach or a dosimetry-based one. Administering an empirical activity is low cost, easy, and the rate and severity of side effects is well known and accepted. On the other side, it can lead to under-treat or over-treat patients, due to the different specific characteristics of the iodine kinetics in each patient. Dosimetry can be both perspective and peri-therapy. A complete dosimetry should take into account both the objectives of killing the lesions and complying the dose constraints to organs at risk, traditionally red marrow (RM) and lungs. Since dosimetry requires repeated measurements of patients and blood samples collections in case of RM dosimetry and, in case of lesion dosimetry, patient imaging is required too, an investment is necessary in terms of man-time and instrumentation employed, the entity strictly dependent on the goals. Although the results obtained are encouraging, a clear superiority of dosimetry-based approach has not been assessed till now [1,2]. Results A complete dosimetry should be both perspective and peri-terapy; it should lead to kill lesions and, at the same time, to avoid side effects. The choice should be made taking into account the goals and the available resources. Conclusions Every center should perform dosimetry in RAIT, in order to improve the safety and the efficacy of a treatment. The level implementation depends on the available resources. The aim of the presentation is to investigate the opportunity of performing dosimetry in Radioactive Iodine Treatment of Metastatic Differentiated Thyroid Cancer (RAIT). RAIT has been established in the management of patients with metastatic thyroid cancer therapy. Since its first use, the optimal activity to be administered has been under discussion. The activity can be determined using an empiric approach or a dosimetry-based one. Administering an empirical activity is low cost, easy, and the rate and severity of side effects is well known and accepted. On the other side, it can lead to under-treat or over-treat patients, due to the different specific characteristics of the iodine kinetics in each patient. Dosimetry can be both perspective and peri-therapy. A complete dosimetry should take into account both the objectives of killing the lesions and complying the dose constraints to organs at risk, traditionally red marrow (RM) and lungs. Since dosimetry requires repeated measurements of patients and blood samples collections in case of RM dosimetry and, in case of lesion dosimetry, patient imaging is required too, an investment is necessary in terms of man-time and instrumentation employed, the entity strictly dependent on the goals. Although the results obtained are encouraging, a clear superiority of dosimetry-based approach has not been assessed till now [1,2]. A complete dosimetry should be both perspective and peri-terapy; it should lead to kill lesions and, at the same time, to avoid side effects. The choice should be made taking into account the goals and the available resources. Every center should perform dosimetry in RAIT, in order to improve the safety and the efficacy of a treatment. The level implementation depends on the available resources.