Patent Application
20130144149
This application claims the priority benefit of Taiwan application serial no. 100144640, filed on Dec. 5, 2011. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.
1. Technical Field
The disclosure relates to a photoacoustic imaging apparatus.
2. Related Art
When a tissue (for example, a living tissue) is irradiated by an electromagnetic wave, the tissue absorbs electromagnetic energy, converts a portion of the electromagnetic energy into acoustic energy, and transmits the acoustic energy as an acoustic wave. Such an effect is referred to as photoacoustic effect. Photoacoustic effect is usually applied to internal imaging of living tissue or sample analysis. For example, photoacoustic effect can be applied to the detection of skin cancer.
Generally speaking, a photoacoustic imaging apparatus includes at least an ultrasonic sensor and an electromagnetic wave source. After a living tissue region is irradiated by using an electromagnetic wave, the living tissue region generates and emits a photoacoustic signal, and the ultrasonic sensor receives the photoacoustic signal to determine imaging characteristics of the living tissue region. However, in a conventional technique, the electromagnetic wave may be reflected or absorbed by other living tissues when it is transmitted to the inside of the living tissue region, so that the quality of the photoacoustic image may be affected. For example, when a photoacoustic imaging apparatus is applied to the detection of melanomas in a conventional technique, since melanomas may grow in the tissue under the epidermis of human skin, the electromagnetic wave is reflected or absorbed by non-uniform tissues (for example, cells, collagenous fibers, or interstitial fluid) in the epidermis. As a result, the melanomas under the epidermis cannot be successfully detected.
According to an embodiment of the disclosure, a photoacoustic imaging apparatus for detecting a photoacoustic image of an object is provided. The photoacoustic imaging apparatus includes an electromagnetic wave source capable of emitting an electromagnetic wave, a first electromagnetic wave transmissible substrate disposed on a transmission path of the electromagnetic wave, a plurality of electromagnetic wave transmitting needles disposed on the first electromagnetic wave transmissible substrate, and an ultrasonic sensor disposed at one side of the object. The electromagnetic wave transmitting needles are suitable for being inserted into the object. The electromagnetic wave is transmitted to at least a part of the electromagnetic wave transmitting needles through the first electromagnetic wave transmissible substrate. The electromagnetic wave is transmitted to the inside of the object through at least the part of the electromagnetic wave transmitting needles. The inside of the object generates an ultrasonic wave in response to the electromagnetic wave. The ultrasonic sensor detects the ultrasonic wave.
According to an embodiment of the disclosure, a photoacoustic sensing structure suitable for guiding an electromagnetic wave to the inside of an object to receive an ultrasonic wave generated by the inside of the object in response to the electromagnetic wave is provided. The photoacoustic sensing structure includes a first electromagnetic wave transmissible substrate, a plurality of electromagnetic wave transmitting needles, and an ultrasonic sensor. The first electromagnetic wave transmissible substrate is disposed on a transmission path of the electromagnetic wave. The electromagnetic wave transmitting needles are disposed on the first electromagnetic wave transmissible substrate and are suitable for being inserted into the object. The electromagnetic wave is transmitted to at least a part of the electromagnetic wave transmitting needles through the first electromagnetic wave transmissible substrate. The electromagnetic wave is transmitted to the inside of the object through at least the part of the electromagnetic wave transmitting needles. The ultrasonic sensor is disposed at one side of the object. The inside of the object generates an ultrasonic wave in response to the electromagnetic wave. The ultrasonic sensor detects the ultrasonic wave.
According to an embodiment of the disclosure, a method of capturing a photoacoustic image is provided. The method includes following steps. An object is provided. A first electromagnetic wave transmissible substrate and a plurality of electromagnetic wave transmitting needles disposed on the first electromagnetic wave transmissible substrate are provided. The first electromagnetic wave transmissible substrate is laid on the object, and the electromagnetic wave transmitting needles are inserted into the object. An electromagnetic wave is transmitted to the inside of the object through the first electromagnetic wave transmissible substrate and at least a part of the electromagnetic wave transmitting needles. The inside of the object generates an ultrasonic wave in response to the electromagnetic wave. The ultrasonic wave is detected.
Several exemplary embodiments accompanied with figures are described in detail below to further describe the disclosure in details.
The accompanying drawings are included to provide further understanding, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments and, together with the description, serve to explain the principles of the disclosure.
The electromagnetic wave source 110 in the present embodiment is capable of emitting an electromagnetic wave L. The electromagnetic wave source 110 in the present embodiment may be a laser generator, wherein the laser generator may be a diode laser generator, a solid laser generator, a gas laser generator, or a dye laser generator. In the present embodiment, the wavelength of the electromagnetic wave L is determined to allow the object 10 to have the highest transmittance. For example, in the present embodiment, the wavelength of the electromagnetic wave L falls within a range of 10 nm to 2400 nm.
In the present embodiment, the first electromagnetic wave transmissible substrate 120 is disposed on the transmission path of the electromagnetic wave L. In the present embodiment, besides being transmissible to electromagnetic wave, the first electromagnetic wave transmissible substrate 120 is further capable of guiding the electromagnetic wave L to the electromagnetic wave transmitting needles 130. To be specific, in the present embodiment, the first electromagnetic wave transmissible substrate 120 includes a first surface 120a, a second surface 120b opposite to the first surface 120a, and electromagnetic wave incident surfaces 120c and 120d, wherein the second surface 120b may be an electromagnetic wave incident surface. The electromagnetic wave transmitting needles 130 is disposed on the first surface 120a. The electromagnetic wave L enters the first electromagnetic wave transmissible substrate 120 through the electromagnetic wave incident surfaces 120c and 120d, the second surface 120b, or a combination of foregoing surfaces. The electromagnetic wave L is transmitted into the electromagnetic wave transmitting needles 130 dispersedly through the first surface 120a under the guidance of the first electromagnetic wave transmissible substrate 120. However, the disclosure is not limited thereto.
Additionally, the first electromagnetic wave transmissible substrate 120 in the present embodiment is made of a soft material. In other words, the first electromagnetic wave transmissible substrate 120 in the present embodiment is a flexible substrate, wherein the material of the flexible substrate may be polyethylene terephthalate (PET), polyimide, or any other suitable material. Because the first electromagnetic wave transmissible substrate 120 in the present embodiment is made of a soft material, when a user is about to insert the electromagnetic wave transmitting needles 130 fixed on the first electromagnetic wave transmissible substrate 120 into the object 10, the first electromagnetic wave transmissible substrate 120 can be closely laid on the surface of the object 10 along the contour of the object 10 so that the electromagnetic wave transmitting needles 130 can be nicely inserted into the object 10.
In the present embodiment, the electromagnetic wave transmitting needles 130 are disposed on the first electromagnetic wave transmissible substrate 120. To be specific, as shown in
It should be mentioned that through the electromagnetic wave transmitting needles 130 in the present embodiment, the possibility that the electromagnetic wave L is absorbed or reflected by the object 10 when it is transmitted to the inside of the object 10 is greatly reduced, so that the electromagnetic wave L can be effectively transmitted to the inside of the object 10. Accordingly, the quality of the photoacoustic image captured by the photoacoustic imaging apparatus 100 in the present embodiment can be considerably improved.
Because the electromagnetic wave transmitting needles 130 in the present embodiment are suitable for being inserted into living tissue, the material of the electromagnetic wave transmitting needles 130 should be biocompatible. For example, the material of the electromagnetic wave transmitting needles 130 may be chitosan or any other suitable material. In the present embodiment, the length and diameter of the electromagnetic wave transmitting needles 130 can be adjusted according to the actual requirement. For example, if the object to be detected is human skin, the length of the electromagnetic wave transmitting needles 130 falls within a range of 100 μm to 1000 μm so that epidermis or dermis of the human skin can be observed. The diameter of the electromagnetic wave transmitting needles 130 falls within a range of 20 μm to 300 μm so that the electromagnetic wave transmitting needles 130 can be easily inserted into human skin within causing too much discomfort.
In the present embodiment, the ultrasonic sensor 140 is disposed at one side of the object 10. The inside of the object 10 generates an ultrasonic wave W in response to the electromagnetic wave L. The ultrasonic sensor 140 detects the ultrasonic wave W generated by the inside of the object 10. To be specific, when the electromagnetic wave L is transmitted to the inside of the object 10, the inside of the object 10 produces thermal expansion and contraction due to the absorption of the electromagnetic wave and accordingly generates the ultrasonic wave W. A signal generated by the ultrasonic sensor 140 after it receives the ultrasonic wave W is appropriately processed so that a photoacoustic image of the inside of the object 10 is obtained.
It should be noted that in the present embodiment, because the ultrasonic wave W needs to run from the object 10 to the ultrasonic sensor 140 through the first electromagnetic wave transmissible substrate 120, the physical characteristic of the first electromagnetic wave transmissible substrate 120 needs to be specially designed so that the ultrasonic wave W won't attenuate when it passes through the object 10 and the first electromagnetic wave transmissible substrate 120. To be specific, in the present embodiment, the first electromagnetic wave transmissible substrate 120 has an ultrasonic wave impedance matching characteristic with respect to the object 10.
The photoacoustic imaging apparatus 100 in the present embodiment further includes a probe 150. The electromagnetic wave L is transmitted to the first electromagnetic wave transmissible substrate 120 through the probe 150. The probe 150 has an opening 150a. The electromagnetic wave L is transmitted to the first electromagnetic wave transmissible substrate 120 through the opening 150a. The opening 150a may be in a linear shape, a circular shape, an array-like shape, or any other suitable shape. The photoacoustic imaging apparatus 100 in the present embodiment further includes an electromagnetic wave transmitter 160 (for example, a fiber bundle) disposed in the probe 150. The electromagnetic wave transmitter 160 transmits the electromagnetic wave L emitted by the electromagnetic wave source 110 to the first electromagnetic wave transmissible substrate 120.
The ultrasonic sensor 140 in the present embodiment is suitable for being passed through by the electromagnetic wave L. To be specific, in the present embodiment, the transmittance of the ultrasonic sensor 140 with respect to the electromagnetic wave L is greater than 60%. In the present embodiment, the electromagnetic wave transmitter 160 has an electromagnetic wave exit surface 160a. In the present embodiment, the ultrasonic sensor 140 is disposed on the electromagnetic wave exit surface 160a. The electromagnetic wave L transmitted in the electromagnetic wave transmitter 160 sequentially passes through the electromagnetic wave exit surface 160a, the ultrasonic sensor 140, and the first electromagnetic wave transmissible substrate 120 and eventually enters the object 10 through the electromagnetic wave transmitting needles 130.
However, the disclosure is not limited to foregoing description, and in other embodiments, the ultrasonic sensor 140 may also be disposed in other ways.
In the present embodiment, the electromagnetic wave transmissible film 145 and the patterned electromagnetic wave transmissible support structure 144 can let an electromagnetic wave having a wavelength between 10 nm and 2400 nm to pass through. To be specific, the electromagnetic wave transmissible film 145 and the patterned electromagnetic wave transmissible support structure 144 are made of at least one of a polymer material, Si, SiO2, Si3N4, Al2O3, a monocrystal material, and other materials that can let an electromagnetic wave having a wavelength between 10 nm and 2400 nm to pass through. Aforementioned polymer material includes at least one of benzocyclobutene (BCB), polyimide (PI), SU8 photoresist, polydimethylsiloxane (PDMS), and other polymer materials.
Additionally, in the present embodiment, the first electromagnetic wave transmissible electrode 142 and the second electromagnetic wave transmissible electrode 146 are made of at least one of ITO and IZO. Moreover, in the present embodiment, the electromagnetic wave transmissible substrate 141 is a glass substrate or a polymer soft substrate. In the present embodiment, each ultrasonic sensing unit 140A further includes an electromagnetic wave transmissible passivation layer 147. The electromagnetic wave transmissible passivation layer 147 is disposed on the second electromagnetic wave transmissible electrode 146 for protecting the second electromagnetic wave transmissible electrode 146.
Below, the electromagnetic wave transmissibility of the ultrasonic sensing units 140A will be validated through an optical simulation. However, this optical simulation is not intended to limit the scope of the disclosure. Those having ordinary knowledge in the art should be able to set parameters of aforementioned components according to embodiments of the disclosure without departing the scope of the disclosure.
In the present optical simulation, the electromagnetic wave transmissible substrate 141 is simulated by a BK7 optical glass having a thickness of 500 μm, the first electromagnetic wave transmissible electrode 142 and the second electromagnetic wave transmissible electrode 146 are respectively simulated by an ITO film having a thickness of 0.1 μm, the gas in the cavity C is simulated by air having a thickness of 1 μm, the electromagnetic wave transmissible film 145 is simulated by a dielectric layer (for example, a SiO2 film) having a thickness of 1 μm, and the electromagnetic wave transmissible passivation layer 147 is simulated by a dielectric layer (for example, a PI film) having a thickness of 0.1 μm. The refractivity of the BK7 optical glass adopted in the present optical simulation is 1.51184, and the extinction coefficient thereof is 0. The refractivity of the ITO film is 1.88, and the absolute value of the extinction coefficient thereof is 0.0056. The refractivity of air is 1, and the extinction coefficient thereof is 0. The refractivity of SiO2 is 1.454, and the extinction coefficient thereof is 0. The refractivity of PI is 1.65, and the absolute value of the extinction coefficient thereof is 0.0056. The transmittance of the ultrasonic sensing units 140A obtained through an optical simulation with foregoing parameters is 76.399%. Namely, the ultrasonic sensing units 140A in the present embodiment have a high transmittance.
Below, the effect that the electromagnetic wave transmitting needles 130 improve the penetration depth of the electromagnetic wave L will be validated through an optical simulation. However, this optical simulation is not intended to limit the scope of the disclosure. Those having ordinary knowledge in the art should be able to set parameters of aforementioned components according to embodiments of the disclosure without departing the scope of the disclosure.
The thickness and refractivity of each layer of human skin are listed in foregoing table 1. By assuming that an electromagnetic wave W passes through a flap of human skin having the parameters listed in foregoing table 1 and performing an optical simulation by using the physical parameters of human skin listed in foregoing table 1, the transmittance of human skin with respect to the electromagnetic wave W of different wavelength is obtained, as shown in
When the electromagnetic wave transmitting needles 130 in the present embodiment are adopted, the electromagnetic wave W can be considered directly entering the human skin from the dermis in table 1. By performing an optical simulation under foregoing condition, the transmittances of human skin to the electromagnetic wave W of different wavelengths are obtained, as shown in
Referring to
In the present embodiment, the step of detecting the ultrasonic wave W includes following steps. First, an ultrasonic sensor 140 is disposed on the transmission path of an electromagnetic wave L, wherein the ultrasonic sensor 140 is suitable for being passed through by the electromagnetic wave L, and the electromagnetic wave L is transmitted to the first electromagnetic wave transmissible substrate 120 after passing through the ultrasonic sensor 140. Next, the ultrasonic wave W is detected by using the ultrasonic sensor 140.
To be specific, in the present embodiment, the first electromagnetic wave transmissible substrate 120 has a first surface 120a and an opposite second surface 120b. The electromagnetic wave transmitting needles 130 is disposed on the first surface 120a. The step of detecting the ultrasonic wave W includes following steps. First, the ultrasonic sensor 140 is provided. Then, the ultrasonic sensor 140 is moved along the second surface 120b to detect the ultrasonic wave W.
In the present embodiment, the first electromagnetic wave transmissible substrate 120 has a first surface 120a and an opposite second surface 120b. The electromagnetic wave transmitting needles 130 are disposed on the first surface 120a. The ultrasonic sensor 140 is disposed on the first surface 120a. The ultrasonic sensor 140 is disposed between the first electromagnetic wave transmissible substrate 120 and the object 10. The ultrasonic sensor 140 is suitable for being passed through by the electromagnetic wave L. The electromagnetic wave L passes through the ultrasonic sensor 140 to be transmitted to the inside of the object 10.
In other words, in the present embodiment, the ultrasonic sensor 140 and the electromagnetic wave transmitting needles 130 are all formed on the first surface 120a of the first electromagnetic wave transmissible substrate 120. When the electromagnetic wave transmitting needles 130 are inserted into the object 10, the ultrasonic sensor 140 contacts the object 10, so that the ultrasonic wave W emitted from the inside of the object 10 can reach the ultrasonic sensor 140 without passing through the first electromagnetic wave transmissible substrate 120. Thus, the photoacoustic imaging apparatus 100A in the present embodiment can capture a photoacoustic image of high quality.
The function of the photoacoustic imaging apparatus 100A in the present embodiment is similar to that of the photoacoustic imaging apparatus 100 in the first embodiment therefore will not be described herein.
Referring to
Unlike that in the first embodiment, in the present embodiment, a user needs not to move the ultrasonic sensor 140 along the first surface 120a. To be specific, the step of detecting the ultrasonic wave W in the present embodiment includes following steps. First, an ultrasonic sensor 140 is provided. Then, the ultrasonic sensor 140 is fixed onto the first electromagnetic wave transmissible substrate 120 to cover the same. Next, the ultrasonic wave W is detected by using the ultrasonic sensor 140.
In the present embodiment, the electromagnetic wave source is a plurality of electromagnetic wave source emitters 110a. The electromagnetic wave source emitters 110a may be laser diodes. The electromagnetic wave source emitters 110a are arranged on the first electromagnetic wave transmissible substrate 120 as an array. Besides, the ultrasonic sensor 140 is disposed between the electromagnetic wave source emitters 110a and the first electromagnetic wave transmissible substrate 120. Because the electromagnetic wave source emitters 110a are arranged on the first electromagnetic wave transmissible substrate 120 as an array, the electromagnetic wave source emitters 110a can supply a uniform and highly intensive electromagnetic wave L to the object 10 such that the performance of the photoacoustic imaging apparatus 100B in the present embodiment can be improved. In addition, the function of the photoacoustic imaging apparatus 100A in the present embodiment is similar to that of the photoacoustic imaging apparatus 100 in the first embodiment therefore will not be described again.
The photoacoustic imaging apparatus 100C in the present embodiment further includes a second electromagnetic wave transmissible substrate 170. The electromagnetic wave source emitters 110a are disposed on the second electromagnetic wave transmissible substrate 170. The second electromagnetic wave transmissible substrate 170 is mounted on the first electromagnetic wave transmissible substrate 120, and the second electromagnetic wave transmissible substrate 170 is between the electromagnetic wave source 110 and the first electromagnetic wave transmissible substrate 120. In other words, after capturing a photoacoustic image of the inside of the object 10, a user can separate the second electromagnetic wave transmissible substrate 170 and the first electromagnetic wave transmissible substrate 120 and discard the used first electromagnetic wave transmissible substrate 120 and electromagnetic wave transmitting needles 130, so as to avoid the risk of contagion. The remaining second electromagnetic wave transmissible substrate 170 and the electromagnetic wave source emitters 110a can be reused so that the cost of capturing photoacoustic images can be reduced. In addition, the function of the photoacoustic imaging apparatus 100C in the present embodiment is similar to that of the photoacoustic imaging apparatus 100B in the third embodiment therefore will not be described herein.
As described above, in an embodiment of the disclosure, a photoacoustic imaging apparatus can effectively transmit an electromagnetic wave to the inside of an object through electromagnetic wave transmitting needles, so that a high-quality photoacoustic image can be captured by the photoacoustic imaging apparatus.
It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the disclosed embodiments without departing from the scope or spirit of the disclosure. In view of the foregoing, it is intended that the disclosure cover modifications and variations of this disclosure provided they fall within the scope of the following claims and their equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 100144640 | Dec 2011 | TW | national |
