Which two variables affect the spatial resolution recorded in the radiographic image? (Select two)

The spatial resolution of a radiographic image is significantly influenced by the source-to-image distance (SID) and the object-to-image distance (OID).

When considering SID, increasing the distance between the radiation source and the image receptor enhances resolution because it reduces the effect of penumbra (the blurred edge of the image). A greater distance allows for more parallel rays of radiation to strike the image receptor, which sharpens the boundaries of the structures being imaged.

OID also plays a crucial role; a smaller distance between the object being imaged and the image receptor leads to better resolution. This is because a decreased OID reduces the amount of scatter radiation reaching the receptor and minimizes the penumbral effect, resulting in sharper images.

The other choices contain factors that, while important to the overall imaging process, do not directly influence spatial resolution in the same way. Beam quality and patient thickness primarily affect image contrast and exposure rather than resolution. Focal spot size and collimation certainly have an impact on resolution, but the question specifically asks for two variables. Film speed and viewing distance relate more to the characteristics of the film or digital sensor and the interpretation phase rather than the fundamental definition of spatial resolution in the imaging technique.