New NIST Standard Helps Ensure Accurate Dosages for Cancer-Fighting Drugs

A newly developed standard by the National Institute of Standards and Technology (NIST) is helping pharmaceutical companies accurately measure radioactivity in a promising class of anticancer drugs. These therapies, based on the radioactive isotope actinium-225, show potential in treating prostate cancer, neuroendocrine tumors, and certain types of leukemia. Precise measurement of radioactivity is critical to ensure the drugs deliver effective doses to tumors while minimizing damage to healthy tissue.

Actinium-225 emits alpha particles that deposit energy over very short distances, making them highly effective at destroying cancer cells when bound to molecules targeting tumors. To assist drug companies in controlling dosage, NIST created the first U.S. standard for measuring actinium-225 radioactivity, linked to the International System of Units. This development enables companies to calibrate their instruments by comparing their measurements against the NIST standard, ensuring accurate dosages for clinical use.

NIST scientists employed the triple-to-double coincidence ratio (TDCR) method to establish the standard. They measured radioactivity by detecting flashes of light emitted from a liquid medium when struck by radioactive particles. This allowed them to precisely quantify the number of decays per second, a measure known as the becquerel. Additional techniques confirmed the reliability of the new standard, which was detailed in the journal Applied Radiation and Isotopes.

With the standard in place, pharmaceutical companies have begun submitting samples to NIST to verify and calibrate their radioactivity measurements. Five companies have already used the service since November, with more on a waiting list. The calibration process involves measuring the radioactivity of a company’s actinium-225 sample in an ionization chamber calibrated to NIST’s standard, ensuring consistent and accurate readings across different facilities and countries. Instructions for accessing the service are available on the NIST website.

The new standard is expected to support FDA review processes and expedite the availability of actinium-225-based treatments. It addresses a critical need for precision in cancer therapy, as incorrect dosages can either fail to treat the cancer effectively or cause unnecessary harm to patients. By providing this calibration service, NIST enhances the ability of pharmaceutical companies and research institutions to safely and effectively deploy new cancer-fighting drugs.

Article by multiple RFHC contributors, based upon information from the National Institute of Standards and Technology (NIST) press release.

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