Radioguided surgery with β radiation: a novel application with Ga68

Abstract

Radio Guided Surgery is a technique helping the surgeon in the resection of tumors: a radiolabeled tracer is administered to the patient before surgery and then the surgeon evaluates the completeness of the resection with a handheld detector sensitive to emitted radiation. Established methods rely on γ emitting tracers coupled with γ detecting probes. The efficacy of this technique is however hindered by the high penetration of γ radiation, limiting its applicability to low background conditions. To overtake such limitations, a novel approach to RGS has been proposed, relying on β− emitting isotopes together with a dedicated β probe. This technique has been proved to be effective in first ex-vivo trials. We discuss in this paper the possibility to extend its application cases to 68Ga, a β+ emitting isotope widely used today in nuclear medicine. To this aim, a retrospective study on 45 prostatic cancer patients was performed, analysing their 68Ga-PSMA PET images to asses if the molecule uptake is enough to apply this technique. Despite the expected variability both in terms of SUV (median 4.1, IQR 3.0–6.1) and TNR (median 9.4, IQR 5.2–14.6), the majority of cases have been found to be compatible with β-RGS with reasonable injected activity and probing time (5 s).

Radioguided surgery with β− radiation in pancreatic Neuroendocrine Tumors: a feasibility study

“…On the other hand, the SUV of healthy pancreas has been found to be more consistent among patients, showing smaller variations. It has however to be stressed that the average value of background SUV (median 2.4) has been found to be significantly higher than in previous studies dedicated to assessing the feasibility of the proposed β-RGS technique in other application cases (of the order of 0.2 for both brain tumors 11,12 and prostate cancer 21 ).…”

“…To this aim, we applied in this study the same approach described in ref. 7,21 , that is based on the computation of the rate of false positive (FP) and false negative (FN) signals. For a given value of the probe sampling time (t probe ), the number of signal counts coming from the tumour and the background is distributed according to a Poisson distribution with mean μ T = R T × t probe and μ H = R H × t probe respectively.…”

“…Following the procedure reported in ref. 11,21 , we used the measured uptake in tumor and nearby healthy tissues to study the sensitivity of a β − probe to the signals of interest, thus evaluating the feasibility of the application of RGS in this case.…”

A DROP-IN beta probe for robot-assisted 68Ga-PSMA radioguided surgery: first ex vivo technology evaluation using prostate cancer specimens

“…Light-collection e ciency was maximized using a 3×3 mm 2 silicon photomultiplier (SiPM C-series 30035, SensL Ltd.). After a rst Monte Carlo based study of such a probe in a Ga-PSMA context (16), a dedicated laboratory characterization has been performed. A detection e ciency of ~90% for 68 Ga b particles and ~2.5% for 511 keV g rays has been found (17).…”

Gold Nanoparticles and Nanorods in Nuclear Medicine: A Mini Review

“…When radionuclides emit γ rays (either directly, as pure γ emitters, or indirectly, as β+ emitters), the radiopharmaceutical is intended for diagnostic imaging. When radionuclides emit β− or α particles (thanks to the cell-damaging properties) the radiopharmaceutical is used for therapeutic applications and, in some recent research studies, even for radio-guided surgery [34][35][36]. Theragnostics is a new term that implies the use of the same molecule, labeled with different radionuclides, for both diagnostic and therapeutic purposes [37][38][39].Radiopharmaceuticals have been increasingly used for medical diagnosis since the late 1940s, when nuclear medicine was born.…”