Immobilization devices are used to:

Immobilization devices are essential tools in medical imaging and radiation therapy, as they serve to fixate a patient's position during procedures. The primary purpose of these devices is to ensure that the patient remains still and in the exact same position throughout the duration of the imaging or treatment process. This fixation is crucial because even slight movements can lead to errors in the procedure, resulting in inaccurate imaging or misalignment of radiation beams, which can affect treatment outcomes.

By securely holding the patient in place, immobilization devices help enhance the precision of imaging and therapeutic interventions. This is especially important in areas like radiation therapy where accurate targeting of tissues is vital to maximizing effectiveness while minimizing exposure to surrounding healthy tissues.

The other options, while they may contribute to aspects of patient care or procedural success, do not specifically address the primary function of immobilization devices. For example, ensuring patient comfort may be a secondary consideration, but it is not the main purpose. Calibration of machines is related to ensuring the equipment is functioning properly, which is a separate concern from patient positioning. Adjusting the internal target does not pertain to the function of immobilization devices, which focus on maintaining the patient's position rather than modifying any anatomical or internal structures.