Patent Number: 
Section: description

(First Embodiment) A first embodiment of the present invention will be described in the following based on FIG. 1. 1 is a collimator, and an external thread is cut on a housing attachment side, having a diameter the same as that of the internal thread at the mounting point of the housing. On the opposite side to the housing attachment side, an external left-hand thread is provided coaxial with the external thread. 2 is a cylindrical jig for attachment and detachment with an internal left-hand thread having the same diameter as the external left-hand thread on the collimator. The cross-sectional area of the jig 2 is smaller than the entrance area of the housing, and smaller than the area around the collimator mounting point, and it is sufficiently long for the operator to reach and work easily. For attachment, the collimator is screwed anticlockwise into the jig for attachment and detachment until it stops. Here, static frictional force is acting between the external left-hand thread of the collimator and the internal left-hand thread of the jig. The external thread of the collimator is then screwed clockwise into the internal thread of the housing, using the grip part of the jig for attachment and detachment. Here, the collimator is screwed into the housing until the dynamical frictional force acting between the external thread of the collimator and the internal thread of the housing exceeds the static frictional force. At the instance when the dynamical frictional force exceeds the static frictional force, screwing of the collimator and the housing is terminated, but if rotation in the clockwise direction is continued, the left-hand threads on the collimator and the jig become disengaged due to the effect of the static frictional force between the collimator and the housing, and so only the collimator can be attached to the housing section easily. On the contrary, to detach the collimator from the housing, the internal left-hand thread of the jig is aligned with the position of the external left-hand thread of the collimator and rotation in an anticlockwise direction is continued, then the internal left-hand thread of the jig becomes screwed into the external left-hand thread of the collimator by the effect of the static frictional force between the external thread of the collimator and the internal thread of the housing. The The screwing is terminated when dynamic frictional force exceeds the static frictional force, but if rotation in the anticlockwise direction is continued, the threads on the collimator and the jig become disengaged due to the effect of the static frictional force between the collimator and the housing, and can be detached. Before and after the attachment and the detachment, the collimator and the jig are fixed by the thread, so that accurate carriage of the collimator and accurate positional alignment become possible. Also, as shown in FIG. 3A, the left-hand thread can be provided between the collimator 7 and the housing 8, and the thread can be provided between the collimator 7 and the jig 6. As shown in FIG. 3B, for the threads between the collimator 10 and the housing 11, the internal thread can be provided on the collimator side, and the external thread can be provided on the housing side. The relationship between the threads of the collimator and the housing in the first embodiment of this invention can be applied to the collimator and X-ray generator attachment and detachment mechanism. Additionally, the relationship between the threads of the collimator and the housing in the first embodiment of this invention can be applied to the collimator and X-ray detector attachment and detachment mechanism. (Second Embodiment) A second embodiment of the present invention will be described in the following based on FIG. 4. A notch for an indentation is placed at a point symmetrical with a certain point on the outer periphery of the collimator with respect to a central point of the collimator. A hook of the projection section is also provided on the opposite side to the side having the internal thread of the cylindrical jig for attachment and detachment 2, so as to be lined up with the indentation. After attaching the collimator to the housing, it is possible to tighten up by aligning the projection of the jig with the indentation of the collimator and rotating in a clockwise direction. This tightening mechanism is also applicable when the projection is provided on the collimator, and the indentation is provided on the jig. The mechanism for tightening the threads of the collimator and the housing in the second embodiment of this invention can be applied to tightening of the collimator and the X-ray generator. Additionally, the mechanism for tightening the threads of the collimator and the housing in the second embodiment of this invention can be applied to tightening of the collimator and the X-ray detector. In the following, the first embodiment according to the invention will be explained referring to the drawings.