Radioactive image apparatus and focus control method thereof

A method of controlling a focus of a radioactive image apparatus having a radioactive ray generating unit which generates radioactive rays onto a subject, an adjustable robot table which includes a subject fixing member for positioning the subject and a test pattern mounting member for receiving one or more test patterns, and a radioactive ray detecting unit which produces a radioactive transmission image formed by irradiating the radioactive rays onto the subject, the method comprising:

• obtaining a radioactive transmission image of the test pattern;
• defining a circle with a given radius in the radioactive transmission image of the test pattern;
• detecting values of pixels located on a circumference of the circle;
• calculating a standard deviation of the values of the pixels located on the circumference of the circle;
• and
• determining the radius of the circle to be an index factor of a resolution in response to the standard deviation being smaller than a preset threshold value.

A method of controlling a focus of a radioactive image apparatus having a radioactive ray generating unit which generates radioactive rays onto a subject, an adjustable robot table which includes a subject fixing member for positioning the subject and a test pattern mounting member for receiving one or more test patterns, and a radioactive ray detecting unit which produces a radioactive transmission image formed by irradiating the radioactive rays onto the subject, the method comprising:

• obtaining a radioactive transmission image of the test pattern;
• defining a figure with a given feature in the radioactive transmission image of the test pattern;
• detecting values of pixels located on the figure;
• calculating a standard deviation of the values of the pixels located on the figure;
• and
• determining the feature of the figure to be an index factor of a resolution in response to the standard deviation being smaller than a preset threshold value.