Calibration aid
A calibration aid may be assembled as follows. First, the standard reference substance is prepared by dissolving ICG dye and albumin protein in water. Then, the carrier sheet of fleece material is soaked therein and dried. After drying the carrier sheet, a thin well defined layer of protein bound dye is present at the surface of the fleece material. The carrier sheet and the backing sheet are laminated into a plastic card. For this, the plastic layers may be laminated tightly together in the framing region for example by welding or by use of adhesive. The plastic card is then sterilized and packed into a sealed package.
1. A calibration aid for fluorescence measurement applications, said calibration aid comprising
(a) a porous carrier body having a front side and a backside;
(b) a dry reference standard substance adhering to at least part of the surface of said carrier body, said reference standard substance comprising albumin protein and a fluorescent dye; and
(c) a backing sheet covering the backside of said carrier body, said backing sheet having a degree of transparency for both electro-magnetic radiation in a spectral range exciting the fluorescent dye to fluoresce and a light emitted due to fluorescence of the fluorescent dye such that the calibration aid will exhibit high intensity of fluorescence when irradiated and viewed at the front side and a low intensity of fluorescence when irradiated and viewed at the backside.
2. The calibration aid according to claim 1 , wherein said fluorescent dye comprises indocyanine green.
3. The calibration aid according to claim 1 , wherein said carrier body is a textile carrier sheet.
4. The calibration aid according to claim 3 , wherein said textile carrier sheet comprises a fleece material.
5. The calibration aid according to claim 4 , wherein said textile carrier sheet comprises polyvinyl alcohol fibers.
6. The calibration aid according to claim 1 , wherein said backing sheet is arranged to laterally extend beyond said carrier body in at least one direction.
7. The calibration aid according to claim 1 , wherein said backing sheet has indicia printed thereon.
8. The calibration aid according to claim 1 , wherein said backing sheet includes paper material.
9. The calibration aid according to claim 1 , further comprising at least one transparent plastic layer configured to serve as a humidity barrier for protection of said carrier body against humidity.
10. The calibration aid according to claim 9 , wherein said plastic layer includes polyvinylchloride (PVC) film material.
11. The calibration aid according to claim 1 , wherein the front side of said carrier body extends over an area of between 100 and 5000 square millimeters.
12. The calibration aid according to claim 1 , wherein the complete outer surface of said calibration aid is sterile.
13. A calibration kit comprising a calibration aid according to claim 12 and packaging material enclosing said calibration aid and configured to keep the outer surface of said calibration aid sterile.
14. A method for producing a calibration aid for fluorescence measurement applications, comprising the steps of
(a) providing a porous carrier body having a front side and a backside;
(b) dissolving a fluorescent dye in a hydrophilic solvent to form a solution;
(c) applying said solution onto said carrier body;
(d) drying said carrier body in order to remove said hydrophilic solvent from said carrier body; and
(e) covering the backside of said carrier body with a backing sheet, said backing sheet having a degree of transparency for both electro-magnetic radiation in a spectral range exciting the fluorescence dye to fluoresce and a light emitted due to fluorescence of the fluorescent dye such that the calibration aid will exhibit high intensity of fluorescence when irradiated and viewed at the front side and a low intensity of fluorescence when irradiated and viewed at the backside.
15. The method according to claim 14 , further comprising the step of dissolving albumin protein in said hydrophilic solvent prior to applying said solution onto said carrier body.
16. The method according to claim 14 , wherein said hydrophilic solvent comprises water.
17. The method according to claim 14 , wherein the backside of said carrier body is covered with said backing sheet such that the backing sheet laterally extends beyond said carrier body in at least one direction.
18. The method according to claim 14 , further comprising the step of printing indicia onto said backing sheet prior to the step of covering the backside of said carrier body with said backing sheet.
19. The method according to claim 14 , further comprising the step of laminating together said carrier body with at least two layers of a transparent plastic material to form a card like object.
20. The method according to claim 14 , further comprising the step of sterilizing the outer surface of said calibration aid.
21. The method for determining the blood flow in a tissue of interest of a living being using a calibration aid as defined in claim 1 , said method including the steps of
(a) injecting fluorescent dye of the same species as the fluorescent dye comprised in the reference standard substance of said calibration aid;
(b) placing said calibration aid in a distance from said tissue of interest said distance being such that both said tissue of interest and said calibration aid can be irradiated simultaneously by a radiation source and viewed simultaneously by a digital camera; and
(c) simultaneously irradiating said tissue of interest and said calibration aid causing said fluorescent dye to fluoresce.