Are cephalogram xrays always necessary for orthodontic treatment or will panoramic xray suffice? what is radiation dosage of each type of xray?

Xrays: Yes a Ceph is needed to determine your skeletal class for proper tooth alignment. Radiation doses vary depending on the machine used and whether or not it is a digital xray (90% less than film) or a film xray.

Different: Each film provides different information, so yes, both are necessary. Total radiation less than you would receive if you spent a day in the mountains skiing, or two days on the beach. As with any medicine, there's a value/risk ratio. The value of the information provided far outweighs the risk. I will not treat an Orthodontic patient without both, it would be like working blind.

Cephalometric Xray: The standard of care for orthodontic treatment as defined by the ADA/AAO requires a cephalometric X-ray as part of the beginning orthodontic records. Without this Xray/tracing, it is impossible to properly determine the skeletal vs dental component of the malocclusion. Many of these xrays are digital, which means much less exposure than old traditional xrays with film.