The ALARA (As Low As Reasonably Achievable) method or principle means our equipment is set to the lower possible settings and we will use it only for a maximum amount of time required for the scan. Our longest scans will not last for more than 20 mins which are perfectly safe. If you have any questions concerning any of this then please give us a call and we will be delighted to go into further detail to help you know that you and your baby are perfectly safe to have a 4d ultrasound scan.