To minimize the gap between two adjacent fields abutting at a certain depth, which technique can be utilized?

To minimize the gap between two adjacent fields abutting at a certain depth, the use of a half beam block is a recognized technique. This method effectively allows for the control of the radiation dose distribution by selectively blocking a portion of the beam. When two adjacent radiation fields are set up, especially in techniques such as tangential beams for breast radiation therapy, gaps can occur due to the divergence of the beams or differences in field sizes. The half beam block helps to ensure that there is overlap between the fields, thus reducing the gap and resulting in a more uniform dose distribution at the targeted depth.

Using wedge filters, increased beam energy, or bolus material each has specific applications, but they do not directly address the issue of minimizing gaps between fields in the same way that the half beam block does. Wedge filters are intended to modify the shape of the dose distribution but do not specifically tackle field abutment. Increased beam energy could help in certain scenarios but might also create new challenges with dose distribution or delivery complexity. Bolus material is used to bring the dose up to the surface and does not play a role in managing the interaction between adjacent fields in the manner needed to eliminate gaps.