Miniaturized gamma camera with very high spatial resolution

Details Miniaturized gamma camera with very high spatial resolution Miniaturized gamma camera with very high spatial resolution

1998-12-22

2001-06-05

Hannaher, Constantine (Department: 2878)

Radiant energy

Invisible radiant energy responsive electric signalling

With or including a luminophor

C250S363020, C250S367000

Reexamination Certificate

active

06242744

ABSTRACT:

The invention relates to a miniaturized gamma camera with high spatial resolution for the localization of tumours, for external diagnostic use or to be utilized during surgical operations.
It is well known that in order to remove a tumour surgically, the surgeon needs to localize it and for that purpose he/she normally uses the results obtained with the diagnostic systems employed to identify the tumour itself (radiography, CAT-scans, NMR, scintigraphy).
However, at the time of surgery, after “opening” the part, the surgeon may still need to localize better the point to be cut and removed and, therefore, he/she may be aided by a so-called “surgical probe”: after injecting into the patient a radio pharmaceutical product that has the peculiarity of attaching itself preferentially in tumour cells, he/she detects the gamma radiations emitted by the radioisotope, present in the molecules of the pharmaceutical product, by means of a probe of the type of a GEIGER-MULLER counter.
The probe is sensitive to gamma radiation in such a way as to give analogue signals proportional to the radioisotope concentration detected. The detected signals are converted into digital signals providing a luminous or acoustic scale proportional to the intensity of the signal. The limit is constituted by the impossibility of providing an image in real time but only the display of the count on areas of interest.
Gamma cameras currently in existence often have very large areas and are not easily handled during surgical interventions in the course of the operations. For this purpose, therefore, surgical probes are alternatively used that are able to localize the tumours but unable to display the receiving areas and hence to effect an imaging to describe the situation under examination.
For example, if a peritumoral lymph node is enlarged and anti CEA antibodies have been injected before the intervention, the probe is placed close to the lymph node: if radioactivity is intense, then the lymph node is clearly invaded by neoplastic cells expressing CEA. Last generation probes (CNR patent No. RM95A000451 of Jul. 13, 1995 and corresponding EPO patent application no. 96924120.7) are already partially able to express well the localization of small tumours based on the rate of counts coming from the areas of interest. The lack of imaging associated to the situation described above, however, does not make it easier for the surgeon to act with absolute certain in identifying the parts to be removed. Also, gamma cameras used in radioimmuno-guided surgery are not so easy to handle as to allow to reach very small zones located between organs, for real-time display of any neoplastic formations and the confirmation of their total elimination after the surgical intervention for their removal.
Object of the present invention is to obtain a veritable miniaturized imaging system sensitive to gamma radiation, of reduced size, usable also for external diagnoses of small tumours (for instance skin melanomas, thyroid exams, etc.), in such a way that the reduced dimensions can allow the total ease of handling of the device which can be held in the palm of a hand, has extremely reduced weight with the ability to display hard to reach areas of interest (between organs). The use of small detectors (areas of roughly 3×3 cm
2
) able to detect accumulations of radioactivity with the resolution of about 2 mm is therefore applicable in this case.
In the radioisotopic characterization of melanomas, and in general of skin tumour, the use of such high spatial resolution detectors is particularly useful: the suspected lesion is easily identifiable with a physical examination, so the detector can be positioned in the location of the suspected lesion and provide a reception map, with a response that can be roughly predicted as YES/NO.
The same line of reasoning applies to groin or armpit lymph nodes.
The device according to the invention comprises a Position Sensitive Photomultiplier (PSPMT) of the last generation coupled with a scintillation crystal matrix, each element having 2×2 mm
2
area (or smaller), a collimator of the same shape and area as the crystals, coupled with suitable electronics for processing the signals from the photo tube and a processing software for real-time visualisation of the areas of interest. The scintillation crystals, all matrix, may be NaI(Tl) or CsI(Tl) or other scintillation crystal.


REFERENCES:
patent: 5783829 (1998-07-01), Sealock et al.
patent: 5864141 (1999-01-01), Majewski et al.
patent: 6021341 (2000-02-01), Scibilia et al.
patent: WO 96/37791 (1996-11-01), None
patent: 9703369 (1997-01-01), None

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