Many newer linear accelerators have virtual:

Newer linear accelerators often feature virtual wedges as a significant technological advancement in radiation therapy. Virtual wedges allow clinicians to manipulate the therapeutic beam without the need for physical wedge devices. This capability provides greater flexibility in treatment planning since virtual wedges can be adjusted electronically to achieve the desired dose distribution and beam shape.

This technology enhances the precision of radiation delivery, enabling more complex treatment techniques that can be tailored to the unique contours of a patient's tumor. By using virtual wedges, therapists can ensure that the prescribed dose is delivered accurately while minimizing exposure to surrounding healthy tissues. It streamlines the treatment process and allows for quicker adjustments as patient anatomy or treatment plans evolve.

In contrast, the other options do not reflect the primary advancements associated with newer linear accelerators. Field sizes refer to the physical dimensions of radiation fields that can be generated, while isodose distribution pertains to the patterns of radiation dose delivered in the treated area. Bolus is used to bring the dose closer to the surface but does not relate to the virtual capabilities of the technology.