Medical Radiology and Radiation Safety. 2014. Vol. 59. No. 3. P. 45-51

NUCLEAR MEDICINE

A.V. Khmelev¹, P.S. Bakay²

Study of the ¹²⁴I Cyclotron Production Parameters Impact for its Activity and Radionuclide Purity

1. Russian Medical Academy for Postgraduate Education, Moscow, Russia. E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it. ; 2. N.N. Blokhin Russian Cancer Research Center of RAMS, Moscow, Russia

ABSTRACT

Purpose: Definition of terms wherein cyclotron-produced ¹²⁴I applicable for using in PET-diagnostics in oncology.

Material and methods: Numerical simulation of ¹²⁴I production process in nuclear reactions initiated in the target TeO₂ by 10–15 MeV proton beam as well as such reaction products decay was carried out.

Results: It is shown that ¹²⁴I activity gains the maximal value (86 mCi) at proton energy E = 12 MeV (for “beam current (I) × irradiation time” (t₀) parameter equaled 100 m A×hour) and it decreases on ~ 10 % at grow of ¹²³Te impurity concentration in the target from 0.5 up to 10 %. Existence of time span after the end of the target irradiation wherein produced ¹²⁴I satisfy to radionuclide purity and activity requirements for application in PET-diagnostics was found. Beginning of this time span depends on proton energy and concentration of impurity ¹²³Te (K_i). ¹²⁴I has become applicable in 2.1–8.3 days from the end of irradiation at energy changing in the range of 10–15 MeV. Beginning of time span grows from 4.7 days up to 5.1 days at K_i increasing from 0.5 up to 10 % at E = 12 MeV and It₀ = 100 μAhour. ¹²⁴I application time grows with increasing of It₀. This time also depends on proton energy and it gains the maximal value of 15.2 days at E = 11 MeV and It₀ = 100 μAhour.

Conclusion: Radionuclide purity and activity of ¹²⁴I are determined by parameters of its cyclotron production – beam current, target irradiation time and proton energy as well as ¹²³Te impurity concentration in the target and time from the end of the irradiation. Dependences of the beginning and duration of time span of cyclotron produced ¹²⁴I for its application in PET-diagnostics from these parameters are established and studied.

Key words: cyclotron, ¹²⁴I radionuclide, activity, radionuclide purity