Research & Development & Innovation

The POSiCS camera - Medical nuclear imaging

Medical background

In Radio Guided Surgery (RGS), a powerful technique to evaluate tumors' proliferation to other organs is to identify and remove the first lymph node from which tumoral cells are spreading, known as Sentinel Lymph Node (SLN). This intervention is usually effectuated through the in vivo injection of a gamma-emitter (Tc-99m) chelated with a nutrient molecule mostly absorbed by tumoral cells' enhanced metabolism. Surgeons can localize and remove SLN with high precision using a gamma probe or a gamma camera, reducing the procedure's invasiveness.
In this context, gamma cameras provide higher spatial resolution than simple probes but are often discarded in RGS procedures due to their large volume and long acquisition times.

The POSiCS project

The POSiCS project aims to build a miniaturized and handle-able gamma camera for RGS and especially SLN biopsy.
The final camera device will provide an improved spatial resolution with respect to probes (in the order of the millimeter) and good sensitivity, reducing the measurement time needed to reliably image tumor-positive SLN to a few seconds. With this device we aim to change the probe-based RGS paradigm to the use of gamma cameras to further reduce the invasiveness of surgeries and improve patients' quality of treatment. 

The POSiCS project aims to bring to surgeons a device that is:

• Compact & lightweight
• Easy to handle and ergonomic
• Completely wireless
• Fast in terms of acquisition time

POSiCS science

Gamma rays detection

The POSiCS camera is a semiconductor-based gamma ray imaging detector optimized for sensing γ-photons emitted by the most common radiotracer in nuclear medicine: Tc-99m (140.5 keV). The detector under production must be capable of identifying the position of incoming gamma rays in a 2D plane, as well as executing source's spectrometry to discriminate the target radiation from background noise and Compton scattering. 

Montecarlo simulations

Numerical simulations indicate that the POSICS-2 camera excels at swiftly detecting even minute tumors (3 mm in radius) within seconds, penetrating deep into tissue. By leveraging a camera-based approach, localization time is significantly reduced, facilitating the mapping of a broader field of view. This enables the adjustment of exposure time to strike a balance between statistical noise and real-time feedback. 

Future goals 

The versatility of the POSICS-2 camera extends far beyond RGS applications. Its compatibility with beta or low-energy gamma emitters makes it suitable for outpatient treatments as well as intraoperative surgery settings.

The project's objective is to construct a fully functional prototype capable of real-world deployment, targeting a minimum Technology Readiness Level (TRL) of 6. Initial testing will focus on applications such as SLN biopsy and mammalian cancer, serving as representative benchmarks for a broad spectrum of low-energy gamma radio tracer-based procedures.

In the near future, the camera will be tested on mice to assess its imaging features in vivo. Moreover, we are examining the possibility of executing ex-vivo tests, by scanning already removed SLN.