What is required in terms of imaging to assist in calculating isodose distributions?

Using two radiographs of the site at different angles provides crucial three-dimensional information that is essential for accurately calculating isodose distributions. The different angles allow for a more comprehensive view of the anatomy involved, facilitating the assessment of the tumor location and the surrounding critical structures. This multi-view approach helps to clarify the spatial relationships among various tissues and assists in precisely contouring the tumor and organs at risk.

In contrast, relying on a single radiograph may not provide sufficient data to visualize the three-dimensional nature of the anatomy, potentially leading to inaccuracies in treatment planning. While a CT scan is often preferred due to its higher detail and ability to provide axial views, in this context, the requirement emphasizes the necessity of using two different radiographs for adequate visualization. An MRI, though beneficial in soft tissue contrast, is not typically included in the essential imaging for fundamental dosimetry calculations in this scenario. Thus, two radiographs from different angles effectively support the determination of accurate isodose distributions.