Photothermographic material and image formation method

A method for forming an image, which comprises developing a photothermographic material comprising a non-photosensitive layer having a thickness of from 2.0 to 2.7 μm and an image-forming layer containing a silver salt of an organic acid, photosensitive silver halide grains and a reducing agent on a support

• wherein:
• said non-photosensitive layer is a protective layer formed on the image-forming layer, and
• at least one of the non-photosensitive layer and the image-forming layer contains at least one hardening agent,
• in a heat development apparatus provided with a preheating section, a heat development section and gradual cooling section so that the ratio of scratch strength of the protective layer measured before the treatment in the heat development apparatus and scratch strength of the protective layer measured 30 minutes after the treatment in the heat development apparatus can be in the range of 1:1 to 1:3 for a surface of the image-forming layer side,
• wherein said scratch strength is measured by a sapphire needle having a tip end curvature radius of 0.1 mm,
• wherein said heat development apparatus is further provided with a deodorizing apparatus and said photothermographic material is exposed and developed with an on-line system comprising an auto carrier capable of automatically transporting the photothermographic material from a plotter to the heat development apparatus,
• wherein a light source for light exposure of the plotter is a laser of a wavelength of 750-800 nm, and main scanning speed on a surface of the photothermographic material is 500-1500 m/second.