Salary variation exists wherever you go. There may be so many reasons for the variations in salary. First of all consider the factors like rural and urban difference. The areas where you get employed is very important. When people come from rural to urban area they can understand the difference very well. So what is your background and where you getting employed do is also very important. This is important because the economical conditions vary from one area to another area. When you study in the rural area school the fee structure is very less. Lot of difference is found in the education level, training level and working conditions. So your geographical background is also very important here.
Just like Medical Billing and Coding feild, Salary of an ultrasound technician depends on the hospital where you have got employed. Some hospitals are run by the charities where they offer every service free or with some nominal charges, there the employees also get fewer salaries. In some other cases, the economical background of the surrounding people is such that you cannot get more fee from them for the services offered to them. In that case also you will not get the salary as expected. Higher the level of education, you can move over to the areas where you will get more money and more scope for the work you do.
Sonogram Tech salary varies because of their experience in some diseases sonography. In the diseases like cardio vascular diseases much experience is required for the technician where his knowledge over sonography play a vital role in deciding the course of treatment and many time doctors will accompany the sonographers while they do the sonography. They should conduct the imaging of cardiovascular system to the perfect level else it may endanger the life of the patient as entire treatment based on their test conducted by them.