Custom blocks provide better conformity primarily because they are designed to match what?

Custom blocks are specifically designed to match the unique anatomical contours of the patient. This personalized approach allows for enhanced dose distribution and minimizes exposure to surrounding healthy tissue. By tailoring the shape and design of the blocks to fit the patient's anatomy, dosimetrists can achieve greater conformity in the radiation treatment plan. This feature is crucial for improving treatment efficacy and reducing the chances of adverse effects.

Using standardized treatment plans or universal treatment fields does not account for the individual variability in patient anatomy, which is why custom blocks are preferred in clinical practice. Historical treatment methods, while valuable, do not emphasize the importance of accurately reflecting the patient's anatomy in current treatment paradigms. Thus, the ability of custom blocks to adapt to the specific shapes and sizes within a patient's treatment area underscores their effectiveness in achieving better conformality.