Photothermographic element with core-shell-type silver halide grains

A negative-acting, photothermographic element comprising a support bearing at least one heat-developable, photosensitive, image-forming photothermogrpahic emulsion layer consisting essentially of:

• (a) preformed core-shell-type, photosensitive silver halide grains containing a total silver iodide content of less than 4 mole %, said core having a first silver iodide content of from about 4-14 mole % based upon the total amount of silver halide in said core, said shell having a second silver iodide content lower than the silver iodide content of said core;
• (b) a non-photosensitive, reducible source of silver;
• (c) a reducing agent for said non-photosensitive, reducible source of silver;
• (d) a binder;
• and
• (e) at least one compound selected from the group consisting of:
• a halogen molecule;
• an organic haloamide;
• and hydrobromic acid salts of nitrogen containing heterocyclic compounds which are further associated with a pair of bromine atoms.