How are lateral brain fields and a posterior spinal field best matched during treatment?

Matching lateral brain fields and a posterior spinal field during treatment is crucial for ensuring adequate dose delivery while minimizing exposure to surrounding healthy tissues. Turning the collimator in the couch allows for precise alignment of the treatment fields to achieve this match.

In radiation therapy, when treating areas like the brain and spinal cord, it is essential to have correctly oriented fields to maintain proper dose distribution. The collimator adjustment enables the radiation beam to effectively cover the target area without compromising the treatment plan. By orienting the couch correctly, it ensures that the beams from different angles converge appropriately at the desired point.

Other methods, such as adjusting the patient's position, might not provide the necessary precision, as they could inadvertently misalign critical structures. Similarly, turning the gantry or using a single beam would not achieve the desired matching of the fields, as they may not accommodate the specific angle needed for optimal treatment. Thus, aligning via the collimator is the most effective and accurate method for field matching in this scenario.