National Academy of Medical Sciences of Ukraine
State Institution "The National Research Center for Radiation Medicine"


ISSN 2313-4607 (Online)
ISSN 2304-8336 (Print)

Problems of Radiation Medicine and Radiobiology

  
 

   

D. . Dzhuzha

National Institute of Cancer of the Ministry of Health of Ukraine, 33/43 Lomonosov St., Kyiv, 03022,
Ukraine

DOSE RELATIONSHIP DURING RADIOABLATION OF THYROID RESIDUAL IN PATIENTS WITH THYROID DIFFERENTIATED CANCER

Objective: to study relationship between the focal adsorbed doses (FAD) in the residual thyroid tissue (RTT) at radioiodine therapy (RIT) in patients with differentiated thyroid cancer (DTC) and efficacy of radioablation (RA).
Materials and methods. FAD in RTT in 221 patients aged 2574 years were analyzed. Scintigraphic investigations were executed using gamma-camera 9200 and single photon emission tomograph . 180. FAD in RTT were determined according to recommendation of the Committee on Medical Internal Radiation Dose.
Results. Mean FAD in RTT was consisted (125.9 8.6) Gy with range 1.81373.4 Gy. Positive effect after first course of RIT was in 77.4 % of patients complete RA of 78 % of RTT was achieved. Mean FAD in cases with complete RA was (147.0 13.3) Gy with range 1.81373.4 Gy. Efficacy of RIT constantly increased from 68.2 to 93.7 % with increasing mean FAD from 30 to 370 Gy. Feather enlarging of FAD did not lead to any significant increasing of efficacy of RIT: enlarging mean FAD from 370 to 776 Gy increased efficacy of RA on 0.4 % only. Repeated RIT decreased FAD in RTT after each course. Using regression analysis was established type of relationship between efficacy of RA and FAD in RTT, according it efficacy of first RA consists at 40 Gy 72.8 %, 150 Gy 84.9 %, 300 Gy 91.2 %, 400 Gy 93.7 %, 500 Gy 95.7 %.
Conclusions. FAD in RTT at RIT differ in large range, it can be explained different anatomical and functional condition of iodine accumulate thyroid tissue after surgical treatment and its radioresistance. Efficacy of RA increases with enlarging of FAD, this relationship is nonlinear. Efficacy of RA has the upper dose threshold in range 350400 Gy. The frequency of thyroid tissue with high radioresistance is approximately 6 %.
Key words: differentiated thyroid cancer, thyroid residual tissue, radioiodine therapy, radioablation, focal adsorbed dose, iodine-131.

Problems of Radiation Medicine and Radiobiology.
2022;27:431-439. doi: 10.33145/2304-8336-2022-27-431-439

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