Prompt: A high-fidelity medical x-ray image featuring a sagittal view of a human skull, emphasizing a detailed and accurate portrayal of the brain's convolutions. The x-ray should prominently display a coin embedded in the frontal lobe with utmost clarity. Ensure that the x-ray effect is convincingly strong, completely eliminating any semblance of bony structures in the skull. Pay close attention to the fine details of the brain's convolutions, providing a scientifically accurate representation. Exclude any unnecessary spinal structures from the image. The emphasis should be on achieving a realistic, grayscale x-ray effect that highlights the brain and the embedded coin with precision and clarity.