What happens to the treatment area if the needles in a Manchester system implant are not crossed?

When the needles in a Manchester system implant are not crossed, it results in a more linear arrangement of the sources. This configuration leads to a reduction in the irradiated volume within the treatment area because the overlap of the treatment beams is minimized. In a crossed arrangement, the sources would cover the treatment volume more effectively by allowing the radiation to converge, thereby maximizing the dose distribution within the intended target. However, when they remain uncrossed, there is a tendency for the radiation to be less uniformly distributed across the treatment area, ultimately treating a smaller volume compared to an appropriately crossed configuration. Therefore, the arrangement directly influences the adequacy and effectiveness of the treatment coverage, making the option of treating less area the correct interpretation of the scenario described.