Abstract: A foldable shelter can have several wall sections joined to form a cylindrical lattice, and a roof section coupled to the wall sections. The wall sections each have a first member pivotally joined to a second member at near their respective midpoints. The shelter is foldable from an expanded state by inverting the roof segment into the interior of the shelter and pivoting the first and second members of the wall sections towards a parallel orientation. The shelter can have fixed length or extendable vertical and horizontal supports to enhance overall rigidity. The shelter can withstand wind loads without external bracing or cable support.

Abstract: An implantable source (40) of therapeutic radiation for brachytherapy is provided as a sealed, biocompatible capsule (410) of plastic (e.g. polyethylene or PEEK) transparent to the radiation. The capsule contains a radiation source (400) comprising particles of a radioactive isotope (e.g. Pd103, I125, Cs131) in a fluid carrier that is resistant to radiation polymerization but solidifies at elevated temperature. It also has a marker (420), and desirably has a socket (430) which accommodates attaching spacers (660) and makes possible linear strands and planar arrays of the capsules. The spacers may be functional, e.g. heat-generating or medication-releasing.