A 15 year old male patient complains of pain in the lower back tooth. History of frequent snacking in between meals.
Intra-oral examination reveals occlusal caries with 16 and 36, proximal caries between 26 and 27 and grossly carious 46.
Which of the following must be used while taking a radiograph for this patient?
Round collimator
Rectangular collimator
Short pointed aiming tubes
Short source-to-skin distance