Cross-Reference to Related Applications

This Patent Application claims priority from Italian Patent Application No. 102022000009350 filed on May 6, 2022, the entire disclosure of which is incorporated herein by reference.

Technical field

The present invention relates to an apparatus for measuring a dose of exposure to a radiation.

Background art

As is known, exposure to radiation can have beneficial effects, for example if the radiation is used to disinfect, or harmful effects, for example if the radiation is absorbed by biological organisms.

A radiation with appropriate wavelength, such as UVC radiation, can be used to sanitise air or disinfect surfaces and objects. Such radiation can be emitted, for example, by UVC lamps.

However, in order to control the effects of a radiation, it is necessary to know the dose of exposure (measured in J/m ² ) to it. For this purpose, it is necessary to calculate the irradiance (measured in W/m ² ), i.e. the radiation flux, and multiply it by the exposure time. Calculating the irradiance requires dedicated optoelectronic type devices. In addition, it is difficult to know the exposure time accurately. These disadvantages affect the indirect measurement of the dose of exposure.

Alternatively, the dose of exposure can be measured via radiometers. However, the radiometers are expensive devices, which require an electrical supply and are limited to specific wavelength ranges.

Therefore, the need is felt for an apparatus that allows to measure a dose of exposure to a radiation in a simple, economical and fast way, especially in situations where it is necessary to make a measurement in several areas or points.

A purpose of the present invention is to provide an apparatus which can overcome the above problems.

Disclosure of the invention

The aforementioned purpose is achieved by an apparatus as claimed in claim 1.

The present invention further relates to a method as claimed in claim 7.

Brief description of the drawings

For a better understanding of the present invention, a preferred embodiment is described below, by way of nonlimiting example and with reference to the accompanying drawings, wherein:

Figure 1 is a perspective view of an apparatus connected to an electronic device according to the present invention;

- Figure 2 is a detail of Figure 1, with parts in section; and

- Figures 3 to 5 are block diagrams of a method according to the present invention.

Detailed description of the invention

With reference to Figure 1, there is indicated by 1 an apparatus according to the present invention.

The apparatus 1 is configured to be connected to an electronic device 2 provided with image acquisition means 3 defining an optical axis A. The electronic device 2 is, for example, a mobile phone, a tablet or a computer. The image acquisition means 3 is, for example, a camera.

The apparatus 1 extends substantially along an axis B, parallel and preferably coincident with the optical axis A when the apparatus 1 is connected to the electronic device 2.

The apparatus 1 comprises a coupling element 4, selectively couplable to the electronic device 2, an emitter

5 and an intermediate body 6, axially interposed between the coupling element 4 and the emitter 5. The intermediate body

6 is configured to accommodate a dosimeter 7, as described in detail hereinafter.

The coupling element 4 (Figure 2) is substantially a clip, comprising a first jaw 11 and a second jaw 12, extending transversely to the axis B and configured to contact respective opposite faces of the electronic device 2, and a joint 13 interposed between the jaws 11, 12. Conveniently, the joint 13 is elastic, for example because it comprises a spring.

In particular, the second jaw 12 contacts the electronic device 2 on the same side as the image acquisition means 3, and has a through-hole 14 of axis B, dimensioned so as not to interfere with the image acquisition means 3.

The intermediate body 6 of the apparatus 1 is carried by the second jaw 12 of the coupling element 4 and is substantially shaped as a hollow parallelepiped.

In particular, a first wall 21 of the intermediate body 6 is parallel and rigidly coupled to the second jaw 12 of the coupling element 4, and has a through-hole 22 of axis B dimensioned similarly to the through-hole 14 of the second jaw 12.

The intermediate body 6 further comprises a second wall 23 which is adjacent to the first wall 21 and has a slot 24 placed and dimensioned to allow the insertion of the dosimeter 7 in a housing 25 of the intermediate body 6.

In particular, the dosimeter 7 comprises a sample holder 31, substantially frame-shaped, a glass substrate 32 carried by the sample holder 31 and lying on a plane orthogonal to an optical axis C of the dosimeter 7, and a photochromic film 33, radiation-sensitive, deposited on the substrate 32. When the dosimeter 7 is inserted in the intermediate body 6, the sample holder 31, and consequently the substrate 32 and the film 33, is parallel to the first wall 21, and the axis C is parallel to, and preferably coincident with, the axis B.

Conveniently, the sample holder 31 has an external projection 34, extending transversely to the axis C, which facilitates the grip thereof for insertion into the intermediate body 6 and extraction therefrom.

The film 33 is made of UV-transparent polymeric material supplemented with a compound which is a dithienylethene derivative with the following chemical structure:

In particular, the IUPAC name of the compound is 1,2- bis (2,4-dimethyl-5-phenyl-3-thienyl)-3,3,4,4,5,5- hexafluoro-1-cyclopentene, and the CAS number is 172612-67- 8.

Such compound is sensitive to UVC radiation (so-called short UV waves) at 254 nm, is weakly sensitive to UVB radiation (so-called medium UV waves) and is not sensitive to UVA radiation (so-called long UV waves). In particular, the compound is initially colourless and turns blue when exposed to UVC radiation.

Optionally, the apparatus 1 comprises a tubular element 41 of axis B, rigidly coupled to the second jaw 12 of the coupling portion 4 and/or to the first wall 21 of the intermediate body 6 and arranged in the cavity formed by the through-holes 14, 22.

The emitter 5 comprises a light source 51 and a filter 52 cooperating with the source 51 to generate a light radiation in a predetermined wavelength range.

In particular, such range is matched to the absorption band of the film 33 and can be obtained with an LED of appropriate wavelength or with a white LED coupled to a filter. In this case, a range corresponding to green light has been selected and the source 51 is a white LED. Therefore, the filter 52 comprises a green bandpass photographic gelatin (with peak at about 530 nm).

The emitter 5 is inserted inside a structure 53 substantially shaped as a front-open box and interlockingly coupled, along a free front edge thereof, to the intermediate body 6. The source 51 of the emitter 5 faces the first wall 21 and has optical axis B. Therefore, the coupling element 4 is configured to align the optical axis B of the emitter

5 with the optical axis A of the image acquisition means 3.

The filter 52 is interposed between the source 51 and the first wall 21 of the intermediate body 6. In particular, the filter 52 is interposed between the source 51 and the dosimeter 7, when the dosimeter 7 is inserted in the intermediate body 6.

The source 51 is powered by the electronic device 2 via a power cable 61.

The operation of the apparatus 1 according to the invention is as follows.

After exposing the dosimeter 7 to a radiation whose dose is to be measured, the method described below is executed.

Initially (Figure 3), in a step 101, the apparatus 1 is applied to the electronic device 2.

Subsequently, in a step 102, a value representative of the light radiation transmitted by the dosimeter 7 is obtained, where is the uncertainty of M.

Finally, in a step 103, a dose of exposure of the dosimeter 7 is calculated as a function of the value wherein is the uncertainty of D .

In particular, the step 102 (Figure 4) comprises a plurality of steps:

- A step 111 of acquiring an image via the image acquisition means 3 with the emitter 5 switched on and the dosimeter 7 inserted in the housing 25. In particular, the image S _RGB is an RGB image and is thus a matrix of pixels, i.e. S _RGB is a matrix wherein each element is a triplet of values representing colour intensity on respective red, green and blue channels.

- Preferably, a step 112 of acquiring an image F _RGB via the image acquisition means 3 with the emitter 5 switched on and without the dosimeter 7. In particular, the image F _RGB is a matrix of pixels with the same dimension as S _RGB . Alternatively, the image F _RGB may be previously stored, being independent of the dosimeter 7, and the step 112 may be avoided.

- Preferably, a step 113 of acquiring an image D _RGB via the image acquisition means 3 with the emitter 5 switched off. In particular, the image D _RGB is a matrix of pixels with the same dimension as S _RGB . Alternatively, the image D _RGB may be previously stored, being independent of the dosimeter 7, and the step 113 may be avoided.

- A step 114 of obtaining an image S _G starting from S _RGB . In particular, the image S _G is a matrix wherein each element is the value representing the colour intensity on the green channel of the respective element of S _RGB . Therefore, the number of values of the image S _G is one third of the number of values of the image S _RGB , since the values of the red and blue channels are not considered. The choice to analyse the green channel (instead of the red and blue channels) is related to the predetermined wavelength range of the emitter 5, which corresponds to the green colour.

- A step 115 of obtaining an image F _G starting from F _RGB , via the same procedure described for obtaining an image S _G starting from S _RGB .

- A step 116 of obtaining an image D _G starting from D _RGB , via the same procedure described for obtaining an image S _G starting from S _RGB .

- A step 121 of obtaining a first normalised image S by normalising the image S _G with respect to the image D _G , i.e. performing the matrix operation S = S _G — D _G .

- A step 122 of obtaining a second normalised image F by normalising the image F _G with respect to the image D _G , i.e. performing the matrix operation F = F _G — D _G .

- A step 123 of calculating the barycentre of the first normalised image S, via known mathematical procedure .

- A step 124 of calculating the barycentre of the second normalised image F, via known mathematical procedure .

- A step 125 of calculating a neighbourhood I _s of radius r of the barycentre of the first normalised image S. In particular, the neighbourhood I _s is the set of (x _s ,y _s ) such that i.e. the set of (x _s ,y _s ) inside a circumference of centre and radius r. The radius r is, for example, 10 pixels.

- A step 126 of calculating a neighbourhood r of radius I _F of the barycentre of the second normalised image F. In particular, the neighbourhood I _F is the set of (x _F ,y _F ) such that i.e. the set of (x _F ,y _F ) inside a circumference of centre and radius r. The radius r is, for example, 10 pixels .

- A step 131 of calculating a first mean value of the neighbourhood I _s via known mathematical procedure.

- A step 132 of calculating a second mean value of the neighbourhood I _F via known mathematical procedure.

- A step 133 of calculating a measurement M as a ratio between the first mean value and the second mean value

- A step 134 of calculating the uncertainty of the measurement M. In particular, the uncertainty is calculated by analysing the propagation of the error, and includes the dispersion of the signals in the neighbourhoods I _s and I _F .

In the step 103 (Figure 3), the dose is obtained as a function of the value via a calibration curve i.e.

In particular, the curve depends on the type of the dosimeter 7, i.e. dosimeters 7 of different types generally have calibration curves with different trends.

Furthermore, the curve may also differ for dosimeters 7 of the same type, because of slight differences in the films 33. Therefore, dosimeters 7 of the same type can have calibration curves with the same trend but which are different from each other, for example translated and/or dilated.

Therefore, the method comprises a plurality of steps for managing different scenarios.

In particular, in a step 141, it is checked whether the apparatus 1 is connected to the electronic device 2. If so, step 142 is executed, otherwise it is returned to the step 101.

In the step 142, it is checked whether a curve for the type of the dosimeter 7 connected to the apparatus 1 has been previously stored. If so, a step 143 is executed. Otherwise, a step 144 is executed, wherein it is necessary to acquire the curve (for example from the producer of the dosimeter 7), and subsequently it is returned to the step

141.

In the step 143, it is checked whether a curve has been previously stored for the specific dosimeter 7 connected to the apparatus 1, i.e. whether the dosimeter 7 currently inserted in the apparatus 1 has already been previously used. If so, the step 102 is executed. Otherwise, a step 145 is executed, wherein the curve is adapted for the type of the dosimeter 7, which has already been previously stored, to the specific dosimeter 7 connected to the apparatus 1, and subsequently it is returned to the step 141.

In particular, the step 145 (Figure 5) comprises a plurality of steps:

- A step 151 of inserting, in the housing for the dosimeter 7, a sample with maximum UV radiation.

- The step 102, wherein the value representative of the light radiation transmitted by the sample with maximum UV radiation is obtained.

- A step 152, wherein it is imposed that a value is equal to the value found in the immediately preceding step 102.

- A step 161 of inserting, in the housing for the dosimeter 7, a sample with minimum UV radiation.

- The step 102, wherein the value representative of the light radiation transmitted by the sample with minimum UV radiation is obtained.

- A step 162, wherein it is imposed that a value is equal to the value found in the immediately preceding step 102.

- A step 171, wherein a curve adapted to the specific dosimeter 7 connected to the apparatus 1 is obtained. In particular, the adapted curve is an affine transformation of the curve for the type of the dosimeter 7, which has already been previously stored, and depends on the values

- A step 172, wherein the curve (p obtained in the step 171 is stored.

The dosimeter 7 loses some of its efficiency during each measurement cycle. Therefore, in a step 181 (Figure 3), subsequent to the step 103, a counter of the number n _cycles of cycles of the dosimeter 7 is incremented by one unit. Subsequently, in a step 182, it is checked whether the number n _cycles is lower than a maximum predetermined number of cycles of the dosimeter 7, for example corresponding to a predetermined percentage of loss of efficiency of the dosimeter 7. If so, it is returned to the step 141. Otherwise, a step 183 of reporting the loss of efficiency of the dosimeter 7 is executed, and subsequently it is returned to the step 141.

Conveniently, the automatic steps of the described method are implemented by a processing unit (not shown) of the apparatus 1, communicating with the electronic device 2 for example via the cable 61, or by the electronic device 2 provided with an application dedicated to the implementation of the described method, or by a further electronic device communicating with the electronic device 2, for example a tablet or a computer when the electronic device 2 is a mobile phone.

Upon examination of the characteristics of the apparatus 1, the advantages of the present invention are evident.

In particular, the apparatus 1 is compact and versatile, and allows to measure a dose of exposure to a radiation in a simple, economical and fast way, for an arbitrary number of dosimeters 7 conveniently placed in the measurement environment and off-line, using any electronic device 2 provided with the image acquisition means 3, for example a simple mobile phone.

The apparatus 1 can be used, for example, to measure doses in hospital environments such as the operating theatres, wherein at least one UVC lamp is installed to sanitise the air or to disinfect surfaces and objects.

Finally, it is clear that modifications and variations can be made to apparatus 1 without going beyond the scope of protection defined by the claims.

For example, the filter 52 may be interposed between the electronic device 2 and the dosimeter 7.

The filter 52 may not be present, if the emitter 5 comprises a source generating the light radiation in the predetermined wavelength range.

The predetermined wavelength range may be different from the one illustrated, in order to maximise the contrast of the image if the photosensitive compound used for the dosimeter 7 assumes a different colour when exposed to the radiation of interest.

The apparatus 1 may comprise batteries for its own power supply and may communicate with the electronic device 2 in wireless mode (without cables). In that case, the cable 61 is not necessary.