Radiographic image processing device, method, and recording medium

A radiographic image processing method comprising:

• performing frequency decomposition for a first radiographic image which is captured by irradiating a subject with radiation and acquiring a plurality of band images indicating a plurality of frequency components of the first radiographic image;
• calculating a scattered radiation component that is caused by the subject and is included in a second radiographic image of the subject which has a linear relationship with an amount of radiation, using the second radiographic image;
• removing the scattered radiation component from the second radiographic image to acquire a scattered-radiation-removed radiographic image;
• determining a conversion function for converting at least one of the band images according to the scattered radiation component included in the second radiographic image;
• converting the at least one band image, using the conversion function, and generating a converted band image;
• reconstructing the scattered-radiation-removed radiographic image and the converted band image to acquire a processed radiographic image;
• and
• estimating the body thickness distribution on the basis of the width of the histogram of the signal value of the second radiographic image,
• wherein the first radiographic image has a pixel value that has a linear relationship with a logarithmic amount of radiation,
• wherein the second radiographic image is obtained by performing inverse logarithmic conversion for the first radiographic image,
• wherein the conversion function is determined on the basis of a ratio of the scattered radiation component to a sum of a primary radiation component included in the radiation and the scattered radiation component,
• wherein the scattered radiation component and the primary radiation component are calculated, using a body thickness distribution of the subject, and
• wherein the ratio is calculated from the calculated scattered radiation component and the calculated primary radiation component.

A non transitory recording medium having stored therein a radiographic image processing program that causes a computer to perform:

• a step of performing frequency decomposition for a first radiographic image which is captured by irradiating a subject with radiation and acquiring a plurality of band images indicating a plurality of frequency components of the first radiographic image;
• a step of calculating a scattered radiation component that is caused by the subject and is included in a second radiographic image of the subject which has a linear relationship with an amount of radiation, using the second radiographic image;
• a step of removing the scattered radiation component from the second radiographic image to acquire a scattered-radiation-removed radiographic image;
• a step of determining a conversion function for converting at least one of the band images according to the scattered radiation component included in the second radiographic image;
• a step of converting the at least one band image, using the conversion function, and generating a converted band image;
• a step of reconstructing the scattered-radiation-removed radiographic image and the converted band image to acquire a processed radiographic image;
• and
• a step of estimating the body thickness distribution on the basis of the width of the histogram of the signal value of the second radiographic image,
• wherein the first radiographic image has a pixel value that has a linear relationship with a logarithmic amount of radiation,
• wherein the second radiographic image is obtained by performing inverse logarithmic conversion for the first radiographic image,
• wherein the step of determining the conversion function determines the conversion function on the basis of a ratio of the scattered radiation component to a sum of a primary radiation component included in the radiation and the scattered radiation component,
• wherein the step of removing the scattered radiation component calculates the scattered radiation component and the primary radiation component, using a body thickness distribution of the subject, and
• wherein the step of determining the conversion function calculates the ratio from the calculated scattered radiation component and the calculated primary radiation component.