WO2013168188A2

WO2013168188A2 - Scintigraphic directional detector

Info

Publication number: WO2013168188A2
Application number: PCT/IT2013/000131
Authority: WO
Inventors: Alessandro Soluri; Roberto Massari
Original assignee: Consiglio Nazionale Delle Ricerche (Cnr)
Priority date: 2012-05-09
Filing date: 2013-05-08
Publication date: 2013-11-14
Also published as: ITRM20120201A1; WO2013168188A3

Abstract

A scintigraphic directional detector comprises a plurality of detecting elements (10) distinct from each other for simultaneously detecting gamma rays directed in different directions, each detecting element (10) comprising at least one scintillation crystal (11) and a corresponding electronic converter (12) associated with the crystal (1 1) to receive an optical signal from the crystal (1 1) and convert it into an electric signal. Each detecting element (10) is associated with a respective collimator made of a material with a high atomic number and designed to block the gamma rays incident upon the detecting element (10) at a predetermined external solid angle (α, β, γ).

Description

DESCRIPTION SCINTIGRAPHIC DIRECTIONAL DETECTOR

Technical field

This invention relates to a scintigraphic directional detector, especially for radio- guided applications for locating lymph nodes or tumours.

More specifically, the invention relates to a hand-held detector of the type comprising a handgrip which can be gripped and operated by an operator and having one end which is used for detection.

Background art

It is known that scintigraphic detectors are instruments used to locate tumour cells or specific diseased parts in a patient by picking up the radiation emitted by a radiopharmaceutical previously administered to the patient and which tends to concentrate in the diseased cells.

Also known are detectors with a wider range of action, called "goniometric probes", one example of which is described in patent application No. WO2011107930.

This goniometric probe comprises a first detecting element which is hollow and tubular in shape and which is divided into at least three longitudinal sectors, each consisting of a scintillation crystal, and a second detecting element consisting of a scintillation crystal housed inside the tubular structure of the first detecting element in such a way as to be laterally screened. The probe also comprises suitable photo-detecting means coupled to the scintillation crystals.

In other words, the probe comprises a scintillation structure divided into a central section used to give axial directionality and a set of angular scintillation sectors capable of indicating the directionality of the radiation.

This directionality is obtained by using crystals made of slightly different materials or having different optical properties (for example, by applying to the crystals coatings with different transmittances and different scintillation properties, for example different characteristic scintillation times).

Thus, goniometric probes of this kind do not comprise collimating systems but a plurality of scintillating structures coupled to optoelectronic devices, in such a way as to obtain the information regarding the different angular projections of the emitted radiation. Although the structure of these probes is intended to detect the directionality of the radiation, the absence of a proper collimating structure is a factor which can lead to not entirely accurate information being provided regarding the emitting source position. The proposed solution was therefore based on the assembling of two or more scintillation crystals capable of recording the axial and angular component of the radiation, without considering the source collimating aspect and without describing how to create such a scintillation structure, especially with regard to angular-shaped crystals, or how to avoid the effects linked to the presence of two or more emitting points, as well as how to assess the space resolution in the absence of dedicated collimation.

It is objectively difficult to detect a source exactly if the source is not properly screened and collimated, especially if the point of inoculation and the lymph node are close to each other. Thus, it is reasonable to expect that a detector with an architecture of this kind is not able to provide adequate space resolutions.

Moreover, on account of the tubular configuration of the crystals, goniometric probes of the type described above are large in size, making them unsuitable for meeting current demand for miniaturized instruments.

Disclosure of the invention

This invention therefore has for an aim to provide a scintigraphic directional detector which overcomes the above mentioned disadvantages of the prior art. More specifically, the aim of this invention is to provide a scintigraphic directional detector with a high space resolution.

Another aim of the invention is to provide a scintigraphic directional detector of reduced size. The aim is fully achieved by the scintigraphic directional detector according to the invention, as characterized in the appended claims.

More specifically, the detector according to this invention comprises, on a single detector, a plurality of detecting elements which are distinct from each other and which are aligned along different orientations, for simultaneously detecting gamma rays directed in different directions, each detecting element comprising at least one scintillation crystal and a corresponding electronic converter associated with the crystal to receive an optical signal from the crystal and convert it into an electric signal.

The detector according to the invention is characterized in that each detecting element is associated with a respective collimator made of a material with a high atomic number and designed to block the gamma rays incident upon the detecting element at a predetermined external solid angle.

The detector comprises a handgrip which can be held in an operator's hand and a detecting terminal associated with the handgrip and having a support which is made of a material with a high atomic number and which has a plurality of channels, inside each of which a respective detecting element is inserted.

More specifically, each crystal is inserted in the respective channel at a position distant from the outside opening of the channel so that a portion of the side wall of the channel, between the crystal and the outside opening, defines the aforementioned solid angle and thus determines the collimation of the radiation directed towards the crystal.

The support is preferably defined by a solid body made of the aforementioned high atomic number material and having blind holes defining the aforementioned channels.

The support extends cylindrically about an axis of extension and the channels comprise a lengthwise channel running along the axis and at least one transversal channel oriented along a direction not parallel to that axis and preferably incident thereon.

In one embodiment, there are two transversal channels, located on opposite sides of the axis. Preferably, the two transversal channels are oriented along directions which diverge from each other in the direction of the radiation emitting source. In one embodiment, the orientation of the transversal channel (or of the transversal channels where there is more than one channel) is inclined to the axis at an acute angle of between 10° and 60°, preferably between 15° and 45°. This orientation thus has a component which is directed along the same orientation (and direction) as the longitudinal channel.

In a different embodiment, the orientation of the transversal channel (or of the transversal channels where there is more than one channel) is perpendicular to the axis of the support.

Preferably, in the latter embodiment, there is a plurality of transversal channels located in succession along the axis, obtaining a probe suitable for laparascopic use.

Preferably, the detecting elements housed in the channels define respective solid detecting angles which do not overlap at least within a minimum distance of 4-5 cm from the detector.

Preferably, also, the detecting elements are arranged in such a way as to cover, in mutual cooperation, an overall display angle of between 60° and 180° during a single measurement.

In a preferred embodiment, the detecting element associated with the lengthwise channel has a variable collimation length. This is obtained by coupling to the outside of the support a screening element at least partly (or alternatively, entirely) made of a material with a high atomic number and by causing the support and the screening element to move translationally lengthwise relative to each other.

The screening element has a front wall which is transversal to the axis and a central collimation hole which is coaxial with the lengthwise channel and such as to define a variable collimation by moving the front wall towards and away from the support.

In a preferred embodiment, the screening element is integral with the handgrip and the support is housed slidably inside the screening element and is moved lengthways of it. For this reason, the screening element internally defines a housing whose length is greater than the length of the support.

Preferably, the screening element has, on a side wall of it, at least one opening located at a respective transversal channel (one opening for each transversal channel) shaped in such a way as to leave the transversal channel uncovered along a full sliding movement of the screening element and the support relative to each other.

Preferably, the screening element also has an outer covering made of a sterilizable material, preferably steel, which does not block gamma radiation.

The detector also comprises a control unit connected to the detecting elements to receive from the electronic converters the signals relating to the radiation received and to drive the detecting elements. Preferably, the control unit is enabled to drive the detecting elements independently in such a way that some can be switched on while the others are switched off.

In a preferred embodiment, the detector further comprises a sound signalling device, preferably vocal, connected to the control unit to emit an acoustic signal which is directional or at different intensity and/or frequencies according to which detecting element is most affected by the radiation at a given instant.

In addition, or alternatively, the detector further comprises a visual signalling device connected to the control unit to emit a visual signal representing one or more detecting elements most affected by the radiation at a given instant.

Preferably, the visual signalling device comprises a plurality of luminous displays, preferably LEDs, located on a front surface of the detecting terminal and the control unit enables the switching on of one or more LEDs directed towards the detecting elements which are most affected by the radiation at a given instant.

Brief description of drawings

The technical features of the invention, with reference to the above aim, are clearly described in the claims below and its advantages are more apparent from the detailed description which follows, with reference to the accompanying drawings which illustrate a preferred, non-limiting embodiment of the invention and in which:

- Figure 1 illustrates a scintigraphic directional detector according to the invention;

- Figure 2 is a cross section of the detector of Figure 1 along a longitudinal plane;

- Figure 3 is an enlargement of a portion of the cross section of Figure 2;

- Figure 4 is a further enlargement of a portion of the cross section of Figure 3;

- Figures 5A-5C show three different technical solutions for the portion of Figure 3 according to a first embodiment;

- Figures 6-8 are three schematic representations of the detector according to the invention in a solution with variable collimation and in three different operating configurations;

- Figure 9 shows the portion of Figure 3 in a configuration for use;

- Figures 10 and 1 1 are enlargements of a portion of the cross section of Figure 2 according to a second embodiment;

- Figure 12 is an enlargement of a portion of the cross section of Figure 2 according to a third embodiment.

Detailed description of the preferred embodiments of the invention

The numeral 1 in the accompanying drawings denotes in its entirety a scintigraphic directional detector according to this invention.

The detector 1 comprises a handgrip 2 which can be held in an operator's hand and a detecting terminal 3 associated with the handgrip 2.

The handgrip 2 is defined by a first portion 2a, defining one end of the detector, opposite the detecting terminal 3, and a second portion 2b, defining a central section of the detector 1.

Preferably, the detector 1 has a main axis of extension "X". The first and second portions 2a, 2b of the handgrip 2 and the detecting terminal 3 following each, in that order, along the axis "X". Below is a detailed description of the detecting terminal 3.

As shown in Figure 2, the detecting terminal 3 comprises a support 4, in the form of a solid body extending along the axis "X", having a plurality of blind channels 5, 6, 7.

The term "solid body" is used to mean a block made of a single material, with suitable holes made in it which define the aforementioned channels 5, 6, 7.

Preferably, the support 4 is made of a high atomic number material, such as lead, which can absorb and block gamma rays, in particular emitted by a radiopharmaceutical .

Advantageously, the channels 5, 6, 7 are aligned along respective orientations which differ from each other.

Preferably, a first channel 5 runs lengthways along the axis "X" and is preferably coaxial with the axis "X" and is open at the front, at a front wall of the support 4, opposite the handgrip 2.

Preferably, there are two other channels 6, 7, transversal and oriented along respective directions not parallel to the axis "X" and preferably incident on the axis "X".

In the embodiment of Figure 2, the two transversal channels 6, 7 are oriented along respective directions which are not incident on each other. In other words, the two transversal channels 6, 7 are axially offset from each other. This may be useful for the construction of the support 4.

The orientations of the transversal channels 6, 7 are inclined to the axis "X" at an acute angle of between 10° and 60°, preferably between 15° and 45°.

Each of the channels 5, 6, 7 houses a detecting element 10 which comprises at least one scintillation crystal 1 1 for converting gamma radiation into light radiation and a corresponding electronic converter 12, also housed in the channel

5, 6, 7 and associated with the crystal 11, for receiving an optical signal from the crystal 11 and converting it into an electric signal, preferably digital.

The crystal 1 1 is preferably sensitive to gamma rays of strength between 30 keV and 1 MeV, which emit light at peak wavelength as a function of their composition in a range from 300 nm - 600 nm. The crystal 11 is between 1 mm and 10 mm in size.

Figure 4 shows in detail the structure of the lengthwise channel 5 (which is structurally identical to the transversal channels 6, 7) and of the detecting element 10 it houses.

Preferably, each crystal 11 is housed in the respective channel 5, 6, 7 at a position behind the outlet of the channel 5, 6, 7 in such a way that the channels 5, 6, 7 (and, in particular, the walls thereof) define respective collimators for the detecting elements 10.

Thus, the position of the crystal 1 1 in the respective channel 5, 6, 7 is such that the crystal 10 is reached only by the gamma rays at a respective solid angle α, β, γ which crosses the opening of the channel 5, 6, 7.

Preferably, the detecting elements 10 housed in the channels 5, 6, 7 define respective solid detecting angles α, β, γ which do not overlap at least within a minimum distance "d" of 9-10 cm from the detector (Figure 9).

Figures 5A-5C show three different embodiments of the detector 1 illustrated in

Figure 2, where the solid detecting angles α, β, γ associated with the detecting elements 10 adopt different values.

In Figure 5A, α=30°, β=60°, γ=90°.

In Figure 5B, a=30°, β=60°, γ-60°.

In Figure 5C, a=45°, β=45°, γ=45°.

Preferably, also, the detecting elements are arranged in such a way as to cover, in mutual cooperation, an overall display angle of between 60° and 180° during a single measurement. This angle is measured in a plane passing through the axis "X" of the detector 1, and hence in the drawing plane of Figures 5A-5C.

Advantageously, at least one of the detecting elements 10 (preferably the detecting element associated with the lengthwise channel 5) has a variable collimating length to modify the display angle (that is to say, the solid angle a associated therewith) by reducing the zone to be analysed and thus allowing a better axial resolution. This is obtained by coupling to the outside of the support 4 a screening element 18 at least partly made of a material with a high atomic number.

The element 18 has a side wall 18a which encloses the support 4 and a front wall 18b transversal to the axis and provided with a collimating hole 14 coaxial with the lengthwise channel 5.

The screening element 18 and the support 4 are slidable relative to each other along the axis in order to give the lengthwise channel 5 the aforementioned variable collimation length.

In the preferred embodiment, the screening element 18 is fixed (and hence integral with the handgrip 2) whereas the support 4 is slidably inserted in the screening element 18 and moved relative to it along the axis "X" through the agency of drive means not illustrated.

Figures 6-8 schematically illustrate the support 4 and the screening element 18 in three different positions, corresponding to three different solid detecting angles a. More specifically, it may be noted that, starting from the configuration of Figure 6, as the distance between the support 4 and the front wall 18b of the screening element 18 increases, so the solid detecting angle a decreases. In Figures 6-8, this angle is 60°, 45° and 30°, respectively.

Preferably, the support 4 is in the shape of a cylinder extending along the axis "X" in such a way as to form a plain slidable coupling with the screening element 18. Preferably, also, the screening element 18 has, on its sidewall 18a, a plurality of through openings 15, each located at a respective transversal channel 6, 7 and shaped in such a way as to leave the transversal channel 6, 7 uncovered for the entire sliding movement of the screening element 18 and the support 4 relative to each other. Preferably, the through openings 15 have the shape of elongate slots extending along the axis "X".

Preferably, the screening element 18 also has an outer covering 13 made of a sterilizable material, preferably steel, which does not block gamma radiation. In effect, the screening element 18 constitutes the part of the detector 1 to be inserted into the patient and must be sterilized before re-use. The outer transversal dimension (diameter) of the screening element 18 and, more specifically, of the outer covering, is between 10 mm and 30 mm.

The length of the screening element 18 is between 30 mm and 300 mm.

Figures 10 and 11 show a different embodiment of the detector 1, which differs from the embodiment described above in that it has only one transversal channel 6 in addition to the lengthwise channel 5, and thus has only two detecting elements

10.

Figure 12 shows a further embodiment of the detector 1 which is suitable for laparoscopy and which differs from the embodiment of Figures 1-9 in that it has four transversal channels 6, 7, 8, 9 oriented perpendicularly to the axis "X". In this embodiment, the transversal channels 6, 7, 8, 9 are offset from each other along the axis "X", that is to say, their respective axes lie in planes which are spaced from each other along the axis "X".

The detector 1 according to the invention also comprises a control unit (not illustrated) connected to the detecting elements 10 and enabled to drive the detecting elements 10 independently in such a way that some can be switched on while the others are switched off. In other words, the single detecting elements 10 can be used individually and independently of the others, selecting only axial or transversal detection, in single probe mode, and thus with the possibility of working with probe angles as required.

Preferably, the detector 1 also comprises a sound signalling device (not illustrated), connected to the control unit to emit an acoustic signal which is directional or at different intensity and/or frequencies according to which detecting element 10 is most affected by the radiation at a given instant.

For example, the sound signalling device emits one or more vocal commands (right-left-up-down) telling the operator what direction the detector must be moved in.

Advantageously, the detector 1 further comprises a visual signalling device (not illustrated) connected to the control unit to emit a visual signal representing one or more detecting elements 10 most affected by the radiation at a given instant. In one embodiment, the visual signalling device comprises a plurality of luminous displays, preferably LEDs, located on a front surface of the detecting terminal. The control unit enables the switching on of one or more LEDs directed towards the detecting elements 10 which are most affected by the radiation at a given instant. In a different embodiment, a luminous indicator on the monitor is used, usually in association with the detector 1. The monitor, which normally shows the recorded count parameters, can thus show the operator the direction most of the radiation is coming from and hence the orientation to be given to the detector 1, thereby making it possible for the operator to locate more quickly and effectively the zone affected by the presence of tumour cells or other specific disease cells.

The indications provided by the acoustic or luminous signals thus constitute a system for "navigating" inside the patient's body cavities since the operator is guided by the visual or sound information and can accordingly point the detector in the direction from which most of the radiation is coming, thus easily tracing the part of the patient affected by the presence of tumour cells or other specific disease cells.

From a strictly technical viewpoint, the positions of the detecting elements 10 are correlated with each other and, consequently, given the measured intensity, it is possible to indicate the direction in which to point the detector 1 , for example by visual signalling (LEDs), thereby tracing the location where most of the activity of the radiopharmaceutical is taking place. If most of the activity is detected by a transversal detecting element, on the left or right of the axial direction, then the signal to orient the detector 1 is provided by a luminous sensor (LED) which indicates the direction in which to orient the detecting terminal 3.

Preferably, as shown in Figure 2, the detector comprises an accelerometer 16 and/or a gyroscope 17 mounted inside the handgrip 2 (preferably inside the first portion 2a) to detect the instantaneous movement of the detector 1 and allow the control unit to determine the position of the detector 1 in space by recording its space coordinates in time. This makes it possible to calculate the path the detector must be made to follow and to display it so that the operator can follow the path with his/her hand in the opposite direction in order to trace the position of interest. The detector of the invention, according to what is described above, is suitable for intraoperative and/or laparoscopic use.

The detector of the invention achieves the preset aims.

In effect, the structure of the detector according to the invention allows investigating a three-dimensional zone encompassing, in a longitudinal plane of the instrument, a very large angle of approximately 180°. This allows immediate identification of high radiation emission zones, that is, zones affected by tumour diseases.

Also, the structure of the detecting elements housed in the channels allows the radiation to be correctly collimated, thus increasing the overall resolution.

Further, the possibility of implementing variable collimation on the lengthwise detecting element means that the resolution can be adapted to different requirements, at least in the axial direction.

Moreover, the detector according to the invention is compact and thus very easy to handle and suitable for intraoperative investigation inside the patient's body cavities.

Lastly, the detector according to the invention considerably simplifies the procedure for tracing the parts of the patient which might be affected by tumour cells or other specific diseases, particularly with the aid of an intuitive "navigating system" based on acoustic and/or visual signals.

Claims

1. A scintigraphic directional detector, comprising:

- a plurality of detecting elements (10) distinct from each other for simultaneously detecting gamma rays directed in different directions, each detecting element (10) comprising at least one scintillation crystal (11) and a corresponding electronic converter (12) associated with the crystal (1 1) to receive an optical signal from the crystal (1 1) and convert it into an electric signal; where each of the detecting elements (10) is associated with a respective collimator made of a material with a high atomic number and designed to block the gamma rays incident upon the detecting element (10) at a predetermined external solid angle (α, β, γ);

- a handgrip (2) which can be held in an operator's hand and a detecting terminal (3) associated with the handgrip (2) and having a support (4) made of a material with a high atomic number, where the support (4) has an axis of extension (X) and a plurality of channels (5, 6, 7, 8, 9) inside each of which a respective detecting element (10) is inserted so that an end portion of the channels (5, 6, 7, 8, 9) defines respective collimators for the detecting elements (10),

characterized in that the channels (5, 6, 7, 8, 9) comprise a lengthwise channel (5) running along the axis (X) and at least one transversal channel (6, 7, 8, 9) oriented along a direction not parallel to the axis (X) and preferably incident upon the axis (X).

2. The detector according to claim 1 , wherein the orientation of the transversal channel (6, 7) is inclined to the axis (X) at an acute angle of between 10° and 60°, preferably between 15° and 45°.

3. The detector according to claim 2, wherein the orientation of the transversal channel (6, 7, 8, 9) is perpendicular to the axis (X).

4. The detector according to any of the preceding claims, wherein the detecting elements (19) housed in the channels (5, 6, 7, 8, 9) define respective solid detecting angles (α, β, γ) which do not overlap at least within a minimum distance (d) of 9-10 cm from the detector (1). .

5. The detector according to any of the preceding claims, wherein the detecting elements (10) are arranged in such a way as to cover, in mutual cooperation, an overall display angle of between 60° and 180° during a single measurement.

6. The detector according to any of the preceding claims, wherein the detecting element (19) associated with the lengthwise channel (5) has a variable collimating length to modify the display angle by reducing the zone to be analysed, thus allowing a better axial resolution.

7. The detector according to claim 6, wherein the support (4) is in the shape of a cylinder extending along the axis (X) and is externally coupled to a screening element (18) made at least partly of a material with a high atomic number, wherein the screening element (18) has a front wall (18b) transversal to the axis (X) and provided with a collimating hole (14) coaxial with the lengthwise channel (5) and wherein the support (4) and the element (18) are mutually slidable along the axis (X) so that the collimating length of the detecting element (5) inserted in the lengthwise channel (5) is made variable.

8. The detector according to claim 7, wherein the screening element (18) has, on a sidewall of it (18a), at least one opening (15) located at a respective transversal channel (6, 7, 8, 9) and shaped in such a way as to leave the transversal channel (6, 7, 8, 9) uncovered along a full sliding movement of the screening element (18) and the support (4) relative to each other.

9. The detector according to claim 7 or 8, wherein the screening element (18) also has an outer covering (13) made of a sterilizable material, preferably steel, which does not block gamma radiation.

10. The detector according to any of the preceding claims, further comprising a control unit connected to the detecting elements (10) and capable of controlling the detecting elements (10) independently so as to make it possible to switch on only some of the detecting elements (10) while the others are switched off.

1 1. The detector according to claim 10, further comprising a sound signalling device, preferably vocal, connected to the control unit to emit an acoustic signal which is directional or at different intensity and/or frequencies according to which detecting element (10) is most affected by the radiation at a given instant.

12. The detector according to claim 10 or 11, further comprising a visual signalling device connected to the control unit to emit a visual signal representing one or more detecting elements (10) most affected by the radiation at a given instant.

13. The detector according to claim 12, wherein the visual signalling device comprises a plurality of luminous displays, preferably LEDs, located on a surface of the detecting terminal (3), preferably a front surface, and wherein the control unit enables the switching on of one or more LEDs directed towards the detecting elements (10) which are most affected by the radiation at a given instant.