Targeted Alpha Therapy (TAT) attracts considerable interests as a next-generaton radiation therapy because it can minimizing unnecessary doses to normal tissues (Fig. 1). In this therapy, radiopharmaceuticals containing α‑emitting radionuclides such as 211At, are administered to the patient. In order to maximize the effect of administration, it is essential to rapidly and accurately evaluate both the chemical forms and the radioactivity.
A difficulty in the preparation of such radiopharmaceuticals is that the radionuclides contained are usually short-lived (e.g. T1/2 of 211At is 7.2 h), but their analyses require long measurement times. One added inefficiency is that, in order to determine their radioactivity and chemical forms, separate instruments are required.
To resolve these issues, we have developed an innovative integrated analysis system named "NuS-Alpha" (Fig. 2). In the system, a thin-layer chromatograph (TLC) and a scintillation device coupled with a high-sensitivity CCD/CMOS camera for α counting, are utilized.
The system, "NuS-Alpha", enables us to separate and visualize the α-emitting radionuclides in a pharmaceutical according to their chemical forms via TLC, thereby enabling simultaneous and real‑time determination of chemical forms and radioactivity.
With this system,
- measurements can be done without interference from X‑rays or other radiation,
- sensitivity has been increased approximately 200‑times (Fig. 3),
- analysis time has been reduced 1/40 times,
- its compact design enables on‑site use in clinical settings or in laboratories with limited space.
These merits will lead to the efficient use of valuable radiopharmaceuticals and to the reduction of radiation exposure of operators.
This analysis system has already been commercialized (Fig. 4) supporting the practical implementation of TAT with 211At. We will then enhance this system further and apply to other kinds of radiotherapy as well as environmental monitoring.
