Medical X-ray CT apparatus

1. An X-ray CT apparatus for acquiring tomographic images of a patient, comprising:

internal devices which include an X-ray source for irradiating the patient with X-rays, and an X-ray detector for detecting the X-rays transmitted through the patient and outputting an X-ray detection signal;

a pedestal which has a rotary portion for mounting the internal devices and rotating the internal devices around the patient, and a support base supporting the rotary portion rotatably;

a gantry cover, having exterior and interior surfaces, configured to cover the pedestal and to form a bore having an opening through which the patient is arranged in the bore, including an expanded cover portion which is so formed as to be expanded from the inner side of the bore toward the opening and to have a peripheral edge portion on the opening side; and

at least one curved member, attached on the interior surface of the expanded cover portion, has first and second ends fixed to the peripheral edge portion, includes a curved portion curved convexly toward the inside of the bore with respect to a virtual straight line connecting the first and second ends, and is configured to be extended along a curved line segment which is obtained by geometrically projecting the virtual straight line onto the expanded cover portion.

2. The apparatus according to claim 1 , wherein the pedestal has fixing parts which fix the gantry cover to the pedestal, and the one of the first and second ends is fixed to the fixing parts.

3. The apparatus according to claim 1 , wherein the curved member is configured by reinforcing the material at the locations where the curved member is to be provided on the expanded cover portion.

4. The apparatus according to claim 1 , further comprising connection members which are attached on the interior surface of the expanded cover portion, wherein each of the connection members is configured to connect the curved member and the peripheral edge portion to each other.

5. The apparatus according to claim 1 , wherein the gantry cover is formed substantially symmetrical with respect to a certain reference plane.

6. The apparatus according to claim 5 , further comprising a second curved member which is attached on the interior surface of the expanded cover portion, wherein the second curved member has other first and second ends fixed to the peripheral edge portion, includes a second curved portion curved convexly toward the inside of the bore with respect to a second virtual straight line connecting the other first and second ends to each other, and is configured to be extended along a second curved line segment which is obtained by geometrically projecting the second virtual straight line onto the expanded cover portion,

wherein the first and second curved members are arranged substantially symmetrical to each other with respect to the reference plane.

7. The apparatus according to claim 6 , further comprising connection members which are attached on the interior surface of the expanded cover portion, wherein each of the connection members is configured to connect the first curved member and the peripheral edge portion, and the second curved member and the peripheral edge portion to each other.

8. The apparatus according to claim 6 , wherein the first and second curved members and the connection members are configured by reinforcing the material at the locations where the members are to be provided on the expanded cover portion.