45Ti, a candidate for positron emission tomography: Study of the cyclotron production

Expanding the PET radioisotope universe utilizing solid targets on small medical cyclotrons

“…Iodine: 124 I Applications. Apart from 99m Tc, radioiodines are the most commonly used radionuclides in nuclear medicine.…”

“…Complementary to the near ideal SPECT isotope 123 I (t 1/2 : 13.2 h, 100.0% EC), the positron emitting 124 I (t 1/2 : 4.2 d, 22.7% b + , 77.3% EC) has been used extensively in immunoPET imaging and other protein-based PET applications due to its well-understood radiochemistry and long half-life. 1,50 Thus far, 124 I has been used for cancer diagnosis, monitoring and treatment planning, as well as mechanistic, and pharmacokinetic studies. [51][52][53][54] Beyond antibodies, 124 I labelled peptides and small molecules targeting neurotransmitters systems, tumor hypoxia, prostate specic membrane antigen (PSMA), and neuroinammation have also been investigated in humans.…”

“…1,50 Thus far, 124 I has been used for cancer diagnosis, monitoring and treatment planning, as well as mechanistic, and pharmacokinetic studies. [51][52][53][54] Beyond antibodies, 124 I labelled peptides and small molecules targeting neurotransmitters systems, tumor hypoxia, prostate specic membrane antigen (PSMA), and neuroinammation have also been investigated in humans. [55][56][57] However, the use of 124 I is not without its limitations, not the least of which is its comparatively low positron yield at a high end-point energy.…”

Thermochromatographic separation of 45Ti and subsequent radiosynthesis of [45Ti]salan

“…The titanium isotope 45 Ti has a half-life of 3.1 h, a high positron branching ratio (β + = 84.8%) and low maximum positron energy (E β+max = 439 keV), negligible secondary gamma emission and a low β end point energy of 1.04 MeV, making it an ideal candidate for use in PET studies [12][13][14]. However, while the radiometal can be produced by transmutation of naturally monoisotopic scandium with low energy protons [15,16], 45 Ti radiochemistry is hampered by the high oxophilicity (θ = 1.0) and hydrolytic instability of Ti 4+ ions in aqueous environments, which necessitate the use of strongly acidic conditions [17,18]. Solid phase extraction of 45 Ti dissolved in acidic solutions by ion exchange chromatography is timeconsuming, cannot easily be automated and often results in non-reactive titanyl species that are unsuitable for production of titanium complexes [19,20].…”

Liquid–liquid extraction in flow of the radioisotope titanium-45 for positron emission tomography applications

“…The bombardment of naturally monoisotopic scandium with low energy protons from a medical cyclotron via the nat Sc(p,n) 45 Ti nuclear reaction is an attractive 45 Ti production route. [9][10][11] Recovery of a radiometal is the first post-production step, which for a highly hydrolyzable metal such as Ti, becomes critical. Currently, the solid phase extraction from acidic solutions onto a cation or anion-exchange resin is the predominant way to separate the 45 Ti from its Sc matrix.…”