Thyroid Remnants Therapeutic Dose Determination Using a Small Field of Gamacamera; Pilot Study

Warsaw Medical Physics Meeting 2015


P. Solny1,2, P. Vlček1, J. Zimák1, L. Jonášová1;
1Clinic of Nuclear Medicine and Endocrynology, Prague, CZECH REPUBLIC, 2Department of Dosimetry and Application of Ionizing Radiation Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University, Prague, CZECH REPUBLIC.


The aim of this pilot study was to investigate and verify the possibilities of dosimetry for patients undergoing first Radioiodine therapy (RAIT) using a small single head mobile gamma camera.


 Camera Solo mobile was used for the measurement of 131I accumulation in remnants of patients' thyroids and 131I accumulating nods (neck region). Vials with a known activity of 131I were used to calibrate the system. The patient-volunteers were around 3 months after thyreoablation due to thyroid carcinoma. The weight of the accumulating remnants or nods was established using ultrasound or roughly estimated using phantom measurements. Two types of collimators - MEGP (medium energy general purpose) and HEGP (high energy general purpose) were tested. Seven patients were examined using the MEGP collimator; HEGP was used for the five patients.


The absorbed doses within remnants or nodes vary from 40 Gy up to 800 Gy with an uncertainty from 25% up to 50% depending mainly on the mass of the remnants estimation. Based on the measurements the administered therapeutic activity is considered to be sufficient for most of the patients, a consequent follow-up will be done.


The dose assessment uncertainty could be significantly reduced by processes optimization. Based on the results appropriate grant for further investigation will be sought out.

Pavel Solný

Practical Info

16-05-2015 10:00
25 minutes 12 seconds