A structure configuring a ridge filter has line symmetry about a line vertical to a depth direction passing the center of the structure. A small structure obtained in such a way that the structure is divided by this line has a bilaterally asymmetric shape about a center line in an iterative direction, and has a point symmetric shape about an intersection between the center line in the iterative direction and the center line in the depth direction. Thicknesses in the iterative direction of an uppermost stream surface and a lowermost stream surface in the depth direction are equal to each other. The structure is configured so that a thick portion in the iterative direction of the uppermost stream surface and the lowermost stream surface is not present in the depth direction.

A coded mask apparatus is provided for gamma rays. The apparatus uses nested masks, at least one of which rotates relative to the other.

A coded mask apparatus is provided for gamma rays. The apparatus uses nested masks, at least one of which rotates relative to the other.

The invention comprises a system for patient specific control of charged particles in a charged particle beam path using one or more trays inserted into the charged particle beam path, such as at the exit port of a gantry nozzle in close proximity to a tumor of a patient. Each tray holds an insert, such as a patient specific insert for controlling the energy, focus depth, and/or shape of the charged particle beam. Examples of inserts include a range shifter, a compensator, an aperture, a ridge filter, and a blank. Trays in a tray assembly are optionally retracted into an output nozzle of a charged particle cancer treatment system. Optionally and preferably, each tray communicates a held and positioned insert to a main controller of the charged particle cancer therapy system.

The invention comprises a system for patient specific control of charged particles in a charged particle beam path using one or more trays inserted into the charged particle beam path, such as at the exit port of a gantry nozzle in close proximity to a tumor of a patient. Each tray holds an insert, such as a patient specific insert for controlling the energy, focus depth, and/or shape of the charged particle beam. Examples of inserts include a range shifter, a compensator, an aperture, a ridge filter, and a blank. Trays in a tray assembly are optionally retracted into an output nozzle of a charged particle cancer treatment system. Optionally and preferably, each tray communicates a held and positioned insert to a main controller of the charged particle cancer therapy system.

In a first aspect, the present invention relates to a beam shaping filter (1) for use in a cone beam computed tomography system. The filter comprises a radiation attenuating element for positioning between an x-ray source of the cone beam computed tomography system and an object to be imaged. The radiation attenuation as function of position in at least a part (2) of the radiation attenuating element is rotationally symmetric with respect to a point of rotational symmetry (3).

In a first aspect, the present invention relates to a beam shaping filter (1) for use in a cone beam computed tomography system. The filter comprises a radiation attenuating element for positioning between an x-ray source of the cone beam computed tomography system and an object to be imaged. The radiation attenuation as function of position in at least a part (2) of the radiation attenuating element is rotationally symmetric with respect to a point of rotational symmetry (3).

A tomography apparatus for readily imaging an object while reducing radiation exposure doses includes a filter that adjusts distribution of a radiation dose transmitted therethrough from a radiation source, a radiation detection unit that detects a radiation dose transmitted through the filter and through an object, a holder that holds the object, an acquisition unit that acquires information about the holder, and a control unit that controls the distribution of the transmitted radiation does according to the information about the holder acquired by the acquisition unit.

A tomography apparatus for readily imaging an object while reducing radiation exposure doses includes a filter that adjusts distribution of a radiation dose transmitted therethrough from a radiation source, a radiation detection unit that detects a radiation dose transmitted through the filter and through an object, a holder that holds the object, an acquisition unit that acquires information about the holder, and a control unit that controls the distribution of the transmitted radiation does according to the information about the holder acquired by the acquisition unit.

There is provided an X-ray CT apparatus including: an X-ray source; a wedge which is disposed between the X-ray source and a subject and in which a shield blocking apart of an X ray is formed; a wedge driving unit for moving position of the wedge; and a system control unit controlling the wedge driving unit during a scan execution period to control the position of the wedge.