JPS5952235A - X-ray film picture reader - Google Patents

Abstract

PURPOSE:To varying >=1 of the distribution amount of light, optical filter transmittivity, etc., and to expands the dynamic range of a parallel light density measurement system by distributing transmitted light into plural pieces of luminous flux and measuring and converting them into electric signals. CONSTITUTION:Light from a light source 1 is passed through a lens 2 and limited by an input-side pinhole 3 to such a spread that necessary resolution is obtained to incident an X-ray film 4. The light transmitted through the film 4 enters a photometric system through a photometry-side pinhole 5. The luminous flux is split into two by a half-mirror 6, and luminous flux Q1 is transmitted through an optical filter 7 and then converted by an optical converter 8 into an electric signal, which is further converted into a voltage signal v1 by a current- voltage converter 10. Luminous flux Q2 is converted by a photoelectric converter 9 into a current signal, which is converted into a voltage signal v2 by a current- voltage converter 11. Pieces of density information on diffusion density values 0-4 on an X-ray film are read by the output signal of a composing circuit without any omission and spoiling spatial resolution.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an X-ray film image reading device that reads X-ray film image information by measuring the density of the X-ray film.

In order to maintain its resolution, a conventional X-ray film image reading device measures density using parallel light whose beam width is the same as that of incident light and output light, as shown in FIG. The density due to this parallel light is called the parallel light density. This parallel light density is expressed by equation (1).

DI = kyg Io / I+ ... (1) Formula (1
), IO is incident light, and (1) is transmitted light that does not include scattered light.

On the other hand, the concentration measured with a general densitometer is the diffused density D2 obtained by measuring the total output light I2 including scattered light with respect to parallel incident light It is. This diffused density D2 is expressed by the formula (2) (%) Generally, there is a relationship between the parallel light density D1 and the diffused density D2 as follows: D t ":: Q D 2--(3)
The coefficient Q is about 1 to 2. This coefficient Q varies depending on the degree of scattering by the X-ray film.

For example, when the coefficient Q=2, the parallel light density becomes DI-8 compared to the diffuse density D2-4. This means that for an X-ray film with the same degree of blackening, a diffuse density measurement system requires 4-digit measurements, whereas a parallel light density measurement system requires 8-digit measurements. are doing.

In this way, in order to read an X-ray film that has density information of diffuse density 1 to 4 with an X-ray film image reading device that uses parallel light density measurement that maintains the resolution of Xa film, it is necessary to use a dynamic This requires a measurement system with a range, which is currently extremely difficult. For example, parallel light density.

With 4 probes, it was possible to measure only up to about 2 in diffusion concentration D2.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an X-ray film image reading device that eliminates the drawbacks of the prior art and is capable of reading X-ray film images with good resolution and in high-density subfields.

The present invention has been made to achieve the above object, and its principle is that in the photometry section of a parallel light concentration measurement system, transmitted light is distributed into a plurality of light beams, each of which is photometered and converted into an electrical signal. It is something that converts.

In each photometric system, at least one of the light distribution amount, optical filter transmittance, photoelectric converter sensitivity, and load resistance value is selected.
This allows the amplifier attached to each photometric system to operate linearly in regions of different amounts of light. In this way, it becomes possible to measure different density regions for each photometric system.

Next, as shown in Figure 3, the electrical signals from each photometric system were combined in such a way that they were connected according to the overall sensitivity ratio of each photometric system, thereby constructing a photometric system that substantially expanded the dynamic range. It is something.

Figure 3 is a diagram showing the output voltage characteristics of the X-ray film transmitted light measurement system, with the horizontal axis representing the amount of X-ray film transmitted light and the vertical axis representing the output voltage of the photometry system, where a is the output of the high density Wako photometry system. Curve b is the output curve of the low-density Wako photometry system, and C is the output curve of the synthetic photometry system.

Next, the present invention will be described in detail along with examples.

FIG. 4 is a diagram showing the overall configuration of an embodiment of the X-ray film image reading device of the present invention.

In the figure, 1 is a light source, 2 is a lens for creating parallel light, 3 is a pinhole on the input side, 4 is an X-ray film, 5 is a pinhole on the photometry side, 6 is a nof mirror, 7 is an optical filter, 8 ，
9 is a photoelectric converter that converts light into an electrical signal; 10 and 11 are current-to-voltage converters each consisting of operational amplifiers (hereinafter simply referred to as operational amplifiers) A+ and A2 and feedback resistors R1 and R2; 12 is a current-to-voltage converter. This is a signal combining circuit for converting output signals v1 and v2 of converters 10 and 11 into a combined signal.

Next, the operation of this embodiment will be explained with reference to FIG.

Light from a light source 1 is converted into a parallel beam by a lens 2, and after being restricted by an input side pinhole 6 to a beam spread enough to obtain the necessary resolution, it enters an X-ray film 4. X
The light transmitted through the line film 4 passes through the photometric side pinhole 5 and enters the photometric system.

In the photometry system, the light beam is first divided into two by a half mirror 6. One light flux Q1 passes through an optical filter 7, and then is converted into a current signal by a photoelectric converter 8, and is further converted into a current signal by an operational amplifier A and a feedback resistor 1 (,
It is converted into a voltage signal IIl by a voltage converter 10. The other light flux Q2 is directly converted into a current signal by the photoelectric converter 9 without passing through the optical filter 7, and further converted into a voltage signal υ2 by the current-voltage converter 11 consisting of an operational amplifier A2 and a feedback resistor R2. Here, the light distribution ratio of the half mirror B is as follows: Luminous flux Q1: Luminous flux Q2=1:
n, the transmittance η of the optical filter 7, and the sensitivity ratio of the photoelectric converters 8 and 9 as (sensitivity of photoelectric converter 8):(sensitivity of photoelectric converter 9)=1:m, then the voltage signal υl, υ2
The ratio r is as shown in equation (4).

r-v2/υ1 = rLmR2/ηRt --(4) On the other hand, the two photometric systems described above have a constant yield input depending on the characteristics of the photoelectric converter 8゜9 and the current-voltage converter 10.11. For light, the output voltage is no longer linear. On the other hand, if the input light is too small, the S/N ratio will be poor and actual measurement will not be possible.

Therefore, the input/output characteristics of the two photometric systems alone are
The result is a curve a+b shown in the figure.

Therefore, the feedback resistors R, , R2, and at the connection point P selected in this overlapping region, connect the curve a to the curve a that is translated in parallel to the sensitivity ratio r of the entire measurement system to obtain the final result. In order to make the input/output characteristics as shown in curve C (see FIG. 3), the current-voltage converters 10 and 11 are
The output voltage signals υ1 and v2 are input to the signal synthesis circuit 12. The output voltage signal of the signal synthesis circuit 12 becomes a curve C shown in FIG.

Note that in this embodiment, the half mirror 6 and the photoelectric converter 80
Although the optical filter 7 is placed between them, it may be omitted depending on how the value of the sensitivity ratio r of the entire measurement system is determined. Conversely, it is also conceivable to place an optical filter between the half mirror 6 and the photoelectric converter 9, if necessary.

5 to 10 show the signal synthesis circuit 12 shown in FIG. 4,
That is, the output voltage signal u1.712 (r=v2
FIG. 4 is a diagram showing the configuration of an embodiment of a signal synthesis circuit that synthesizes the output voltage signal v3 corresponding to the curve C shown in FIG. In the figure, 14. 14A and 14B are logarithmic converters, 15 is an adder, 16 is a comparator, 16B is a digital comparator, 17° 17A, 17B is a multiplexer,
18.18A,.

18B is an analog-to-digital (hereinafter simply referred to as A/D) converter, 19.19A and 19B are digital-logarithmic converters, and 20 is a multiplier.

In the first embodiment, as shown in FIG. 5, voltage signals υ1 and v
2 is first input to analog logarithmic converters 14A and 14B. After a signal corresponding to -r is added to the signal corresponding to lOgL'l by an adder 15, the signal is input to a multiplexer 17 together with a signal corresponding to Iogv2. Further, the voltage signal v2 is input to the comparator 16 and compared with the voltage ZIS corresponding to the connection point P in FIG. and,
When the output of the comparator 16 is v2)v3, the output of the multiplexer 17 outputs a signal corresponding to kygr-l-1ogv, and otherwise outputs a signal corresponding to Iogv, . ing. These output signals are A/D converted by the next stage A/D converter 18 and output as digital signals.

In the second embodiment, as shown in FIG.
v2 is first converted to A by A/D converters 18A and 18B.
After /D conversion, the operations performed analogously in the first embodiment are digitally performed.

As shown in FIG. 7, the third embodiment has a configuration similar to that of the second embodiment, but a digital logarithmic converter 19 that digitally performs logarithmic conversion is placed after the multiplexer 17. Along with this, the adder 15 of the second embodiment
(adds a signal equivalent to Iogr) is replaced with a multiplier 20 (multiplies a signal equivalent to γ).

In the fourth embodiment, as shown in FIG.
) When v s is 0, outputs ul, otherwise outputs υ2. The output of multiplexer 17A is input to analog logarithmic converter 14, and its output is divided into two. After one output is added with a signal corresponding to lOgr by an adder 15, it is input to the second multiplexer 17B together with the other output. The second multiplexer 17B outputs the signal applied to kygr when v2>υS, and otherwise outputs the output of the analog logarithmic converter 14. The output of the second multiplexer 17B is A/
The signal is A/D converted by a D converter 18 and output as a digital signal.

In the fifth embodiment, as shown in FIG. 9, the operations after the first multiplexer 17A in the fourth embodiment are performed digitally.

The sixth embodiment has a configuration similar to the fifth embodiment, but a digital logarithmic converter that digitally performs logarithmic conversion is arranged after the second multiplexer 17B. The adder 15 in the example is replaced with a multiplier 20.

It goes without saying that the present invention is not limited to the embodiments described above, and can be modified in various ways without changing the gist thereof. For example, in addition to the above embodiments, the signal synthesis circuit may include a logarithmic converter and an adder.

Various circuit configurations are possible by replacing the arrangement of multipliers, A/D converters, multiplexers, and comparators.

As explained above, the conventional X-ray film image reading device could only measure the diffusion density up to θ~2, but according to the present invention, the density on the X-ray film over the diffusion density θ~4 can be measured. Information can be read completely and without loss of spatial resolution.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of parallel light concentration measurement, FIG. 2 is a diagram showing an example of scattered light concentration measurement, FIG. 3 is a diagram for explaining the present invention in detail, and FIG. 4 is a diagram showing the present invention. Figures 5 to 10 are diagrams showing the overall configuration of an embodiment of the X-ray film image reading device of the invention, and are diagrams showing the configuration of an embodiment of the signal synthesis circuit. 1. Light source, 2. Lens, 3. Input end pinhole, 4.
line film, 5 photometric side pinhole, 6 half mirror,
7. Optical filter, 8, 9... photoelectric converter, 10.
tl・Current-voltage converter, 12・Signal synthesis circuit. Agent Patent Attorney Aki 1) Shu Ki

Claims (1)

[Claims] X with a parallel light generating mechanism, a slot, a photoelectric converter, and a photoelectric converter
In the linear film image reading device, there is provided a light flux distributing means for distributing the transmitted light passing through the slits into a plurality of light fluxes, a photoelectric converter for converting each of the distributed light fluxes into electrical signals, and an output signal of each photoelectric converter. An X-ray film image reading device characterized by comprising a signal synthesis circuit for synthesizing.