Dose Calibrator with Extended Range for Theranostic Hot Cell Applications

The Extended Range Dose Calibrator is specifically designed for theranostic nuclear medicine, where the same radiopharmaceutical is used for both diagnostic imaging (low activity) and therapy (high activity). Theranostic agents such as Lu-177, Y-90, Ac-225, and I-131 present a unique measurement challenge: the same instrument must accurately measure microcurie-level diagnostic doses and curie-level therapy doses. Standard dose calibrators typically sacrifice accuracy at one end of this range. This instrument maintains ±5% accuracy from 0.1 μCi to 10 Ci — a dynamic range of 10⁸ (100 million to one). The extended range is achieved through a dual-chamber design: a small, high-sensitivity chamber for low activities and a large, high-capacity chamber for high activities, with automatic switching between chambers.

This dose calibrator is designed for nuclear medicine departments that perform theranostic procedures using radiopharmaceuticals for both imaging and therapy. Primary applications include measuring Lu-177 DOTATATE or PSMA doses for PRRT (therapy doses ranging from 100 to 200 mCi), quantifying Lu-177 diagnostic doses (5–10 mCi) for pre-therapy imaging, measuring Y-90 microsphere doses (20–40 mCi per vial) for liver cancer treatment, quantifying Ac-225 PSMA doses (50–100 μCi) for targeted alpha therapy, and verifying I-131 doses for thyroid cancer therapy (30–200 mCi). The instrument also supports diagnostic applications using the same isotopes at much lower activities, enabling theranostic centers to use a single dose calibrator for the entire patient journey from diagnostic imaging through therapy administration and post-therapy monitoring.

The Extended Range Dose Calibrator maintains ±5% accuracy across the entire 0.1 μCi to 10 Ci range through its dual-chamber design. The small chamber — optimized for activities below 10 mCi — achieves high sensitivity and low background, enabling accurate measurement of microcurie-level doses that would be lost in the noise of a standard chamber. The large chamber — optimized for activities above 10 mCi — provides sufficient capacity for curie-level therapy doses that would saturate a standard chamber. The instrument automatically selects the appropriate chamber based on the detected signal, switching seamlessly without user intervention. For Lu-177 theranostics, this capability is particularly valuable. A typical PRRT patient receives a diagnostic dose of 5–10 mCi Lu-177 DOTATATE for pre-therapy imaging, followed a few weeks later by a therapy dose of 150–200 mCi. With standard dose calibrators, these measurements require different instruments or different range settings, increasing complexity and the risk of errors. The Extended Range instrument handles both measurements automatically with the same ±5% accuracy. For Ac-225 targeted alpha therapy, the activity range is even more extreme: diagnostic doses may be 10–20 μCi, while therapy doses range from 50–150 μCi. This 10-fold range within the microcurie region would challenge standard instruments, but the dual-chamber design handles it with ease. The instrument includes a comprehensive nuclide library with calibration factors for all common theranostic isotopes, including Lu-177 (both low-energy and high-energy calibration options), Y-90 (pure beta emitter requiring specialized calibration), Ac-225 (complex decay chain), and I-131 (multiple photon emissions). For Y-90, which emits no gamma radiation suitable for standard dose calibrator detection, the instrument uses a specialized bremsstrahlung measurement protocol that correlates the X-ray signal with beta activity, achieving ±10% accuracy — the best available for this challenging isotope. The remote display shows measured activity in mCi or MBq, and the data logging system maintains records for regulatory compliance. For theranostic centers, the key benefit is simplified workflow: a single instrument supports the entire range of activities for each patient, eliminating the need to transfer samples between instruments or rely on decay calculations that introduce uncertainty. The extended range also reduces costs by eliminating the need for separate low-activity and high-activity calibrators. For patient safety, the consistent accuracy across the range ensures that both diagnostic and therapy doses are correct, supporting optimal treatment outcomes. The Extended Range Dose Calibrator is an essential tool for any nuclear medicine department performing theranostic procedures.