Development of a positron probe for localization and excision of brain tumours during surgery

Abstract

The survival outcome of patients suffering from gliomas is directly linked to the complete surgical resection of the tumour. To help the surgeons to delineate precisely the boundaries of the tumour, we developed an intraoperative positron probe with background noise rejection capability. The probe was designed to be directly coupled to the excision tool such that detection and removal of the radiolabelled tumours could be simultaneous. The device consists of two exchangeable detection heads composed of clear and plastic scintillating fibres. Each head is coupled to an optic fibre bundle that exports the scintillating light to a photodetection and processing electronic module placed outside the operative wound. The background rejection method is based on a real-time subtraction technique. The measured probe sensitivity for (18)F was 1.1 cps kBq(-1) ml(-1) for the small head and 3.4 cps kBq(-1) ml(-1) for the large head. The mean spatial resolution was 1.6 mm FWHM on the detector surface. The gamma-ray rejection efficiency measured by realistic brain phantom modelling of the surgical cavity was 99.4%. This phantom also demonstrated the ability of the probe to detect tumour discs as small as 5 mm in diameter (20 mg) for tumour-to-background ratios higher than 3:1 and with an acquisition time around 4 s at each scanning step. These results indicate that our detector could be a useful complement to existing techniques for the accurate excision of brain tumour tissue and more generally to improve the efficiency of radio-guided cancer surgery.

β-Radioluminescence Imaging: A Comparative Evaluation with Cerenkov Luminescence Imaging

“…With respect to photon sensitivity, a b prototype using a phoswich detector for electronic g rejection exhibited lower photon sensitivity (2.5-14.0 cps/kBq depending on collimation) (14) than this b-RLI system (37.3 cps/kBq). However, b prototypes using the g-subtraction technique that was adapted for b-RLI demonstrated a greater photon sensitivity (.100 cps/kBq) (12,13,16). b prototypes have a similar spatial resolution (1.6-5 mm) (13,15,16) and limited depth penetration (16).…”

“…However, b prototypes using the g-subtraction technique that was adapted for b-RLI demonstrated a greater photon sensitivity (.100 cps/kBq) (12,13,16). b prototypes have a similar spatial resolution (1.6-5 mm) (13,15,16) and limited depth penetration (16). Furthermore, b probes also exhibit decreasing signal intensity and spatial resolution with increasing object-scintillator distance (14,15).…”

“…Scintillators can produce between 1,000 and more than 100,000 photons per MeV, depending on the material used (11). Scintillators have been incorporated into handheld radioactive probes and cameras for radio-guided surgical applications (12)(13)(14)(15)(16).…”

Performance of beta- and high-energy gamma probes for the detection of cancer tissue in experimental surgical resection beds

“…18 F-FDG accumulation in malignancies is based on a high cellular uptake, increased glycolytic rate, and subsequent trapping, yielding excellent tumor-to-background ratios (TBR) that frequently exceed 10:1 in many cancers [4]. In addition to the metabolic accumulation of 18 F-FDG, the physical properties of Fluorine-18 are also advantageous for intraoperative tumor detection.…”

“…18 F-FDG accumulation in malignancies is based on a high cellular uptake, increased glycolytic rate, and subsequent trapping, yielding excellent tumor-to-background ratios (TBR) that frequently exceed 10:1 in many cancers [4]. In addition to the metabolic accumulation of 18 F-FDG, the physical properties of Fluorine-18 are also advantageous for intraoperative tumor detection. The positron (positively charged electron) emitted from the protonrich/neutron-deficient radionuclide travels only a short distance (0.5 mm mean range and 2.4 mm maximum range in water [5,6]) in tissue before it interacts with a negatively charged electron and subsequent annihilates.…”