Modular patient support system

A patient pod configured to support a patient during a medical treatment, the pod comprising:

• a semi-cylindrical shell structure configured to be concave upward to provide a patient space, the shell structure extending transversely between a first lateral edge and a second lateral edge and extending longitudinally between a proximal edge and a distal edge, the shell structure comprising a top, concave surface and a bottom, convex surface that faces outward, away from the patient space;
• the top, concave surface configured to be parallel to the bottom, convex surface, except at the first and second lateral edges;
• the first and second lateral edges being tapered to reduce the effect of changes in the water equivalency between the shell structure and a space above the shell structure;
• the top, concave surface comprising a separate, flat, inwardly-facing portion that tapers away from the top, concave surface of the shell structure to a narrower upper tip,
• the bottom, convex surface comprising a separate, flat, outward facing portion that tapers away from the bottom, convex surface and converges to meet the flat, inwardly-facing portion at the narrower upper tip.