Medical image processing apparatus, X-ray CT apparatus, and image processing method

An X-ray computed tomography (CT) apparatus, comprising:

• processing circuitry configured to
• acquire pieces of X-ray image data on a subject at a plurality of time phases,
• calculate an index value obtained by comparing a pixel value of X-ray image data of a reference time phase among the pieces of X-ray image data of the time phases and a pixel value of each of the pieces of X-ray image data of the time phases without extracting a lung field region of the subject from the pieces of X-ray image data, and
• select at least one of the pieces of X-ray image data of the time phases based on the index value calculated for each of the time phases and associate the one piece of X-ray image data with a breathing time phase in at least one of inspiration and expiration of the subject, wherein
• the reference time phase is any one of the time phases, and
• the processing circuitry
• performs difference processing on each of the pieces of X-ray image data of the time phases and the X-ray image data of the reference time phase to calculate the index value,
• selects a time phase at which the index value calculated reaches the maximum value as a time phase of maximum inspiration of the subject, and
• selects a time phase at which the index value calculated reaches the minimum value as a time phase of maximum expiration of the subject.

An image processing method, comprising:

• storing, in storage circuitry, pieces of X-ray image data on a subject obtained at a plurality of time phases from a medical image diagnostic apparatus;
• calculating an index value obtained by comparing a pixel value of X-ray image data of a reference time phase among the pieces of X-ray image data of the time phases and a pixel value of each of the pieces of X-ray image data of the time phases without extracting a lung field region of the subject from the pieces of X-ray image data;
• selecting at least one of the pieces of X-ray image data of the time phases based on the index value calculated for each of the time phases and associating the one piece of X-ray image data with a breathing time phase in at least one of inspiration and expiration of the subject, the reference time phase being any one of the time phases;
• performing difference processing on each of the pieces of X-ray image data of the time phases and the X-ray image data of the reference time phase to calculate the index value;
• selecting a time phase at which the index value calculated reaches the maximum value as a time phase of maximum inspiration of the subject;
• and
• selecting a time phase at which the index value calculated reaches the minimum value as a time phase of maximum expiration of the subject.