System for adjusting the energy level of a proton beam provided by a cyclotron, a cyclotron target holder assembly with a removable degrader, a removable degrader for use in a cyclotron target holder assembly, and methods of use thereof

An assembly for a fixed-energy cyclotron, wherein the cyclotron is configured to produce a particle beam, the assembly comprising:

• a target holder assembly comprising a target body that includes:
• a first region configured to hold a target material;
• a second region with a receiving slot;
• and
• a third region including a receiving section for receiving the particle beam from the cyclotron;
• and
• a removable degrader comprising an attenuation disc;
• wherein:
• the receiving slot is configured to receive the removable degrader;
• the removable degrader is configured for removable insertion into the receiving slot such that, when (a) the removable degrader is in the receiving slot, (b) the target material is held in the first region of the target body, and (c) the particle beam travels into the receiving section, the attenuation disc is positioned in a path of the particle beam that extends from the receiving section to the target material;
• and
• the attenuation disc is configured to reduce an energy level of the particle beam prior to the particle beam reaching the target material.