Configurable γ Photon Spectrometer to Enable Precision Radioguided Tumor Resection

Area of Science:

• Medical instrumentation
• Nuclear medicine
• Semiconductor device physics

Background:

• Surgical tumor resection aims for complete cancer cell removal, but microscopic disease is often missed, leading to recurrence.
• Radioguided surgery (RGS) uses radioisotopes to tag cancer cells, but requires precise localization of these cells within tissue margins.
• Current gamma photon spectrometers for RGS are often mm-scale, limiting specificity and spatial resolution.

Purpose of the Study:

• To develop a compact, high-resolution integrated circuit (IC)-based gamma spectrometer for intraoperative use in RGS.
• To enable precise measurement of single gamma photons and their incident energy with sub-keV resolution.
• To create a versatile spectrometry system adaptable to diverse surgical scenarios in RGS.

Main Methods:

• Designed and implemented a 9.9 mm² IC gamma spectrometer using 180 nm CMOS technology.
• Utilized small 2x2 µm reverse-biased diodes with low capacitance to generate millivolt signals from gamma interactions.
• Developed a low-power energy spectrometry method based on signal decay time measurement, implemented in configurable pixel architectures.

Main Results:

• Achieved sub-keV energy resolution and a 1.315 MeV energy dynamic range.
• Demonstrated the ability to resolve activities as low as 1 µCi for common gamma-emitting radioisotopes (⁶⁴Cu, ¹³³Ba, ¹⁷⁷Lu).
• The IC-based spectrometer successfully measured single gamma photons and their incident energy.

Conclusions:

• The developed IC gamma spectrometer offers a significant advancement for radioguided surgery.
• Its high specificity and configurable design can improve intraoperative visualization of cancer cells.
• This technology has the potential to enhance surgical outcomes by reducing cancer recurrence.