An apparatus for determining whether a blood vessel is obstructed, comprising: an interface for communication with an imaging device , wherein said imaging device comprises a transmitter and a receiver , a user interface , and a processor , wherein the processor is programmed to perform the following steps: display to the user, via the user interface , where to place the imaging device on a patient's body, instruct the imaging device to transmit radiation, receive reflected radiation from the imaging device , process the reflected radiation using machine learning to determine from the reflected radiation whether the imaging device is located correctly relative to a blood vessel of the patient, display to the user, via the user interface , if the imaging device is not located correctly and to reposition the imaging device until the imaging device is correctly located, display to the user, via the user interface , to apply pressure to the patient's blood vessel using the imaging device , instruct the imaging device to transmit further radiation, receive further reflected radiation from the imaging device , and determine from at least the further reflected radiation whether the blood vessel is obstructed. an interface for communication with an imaging device , wherein said imaging device comprises a transmitter and a receiver , a user interface , and a processor , wherein the processor is programmed to perform the following steps: display to the user, via the user interface , where to place the imaging device on a patient's body, instruct the imaging device to transmit radiation, receive reflected radiation from the imaging device , process the reflected radiation using machine learning to determine from the reflected radiation whether the imaging device is located correctly relative to a blood vessel of the patient, display to the user, via the user interface , if the imaging device is not located correctly and to reposition the imaging device until the imaging device is correctly located, display to the user, via the user interface , to apply pressure to the patient's blood vessel using the imaging device , instruct the imaging device to transmit further radiation, receive further reflected radiation from the imaging device , and determine from at least the further reflected radiation whether the blood vessel is obstructed. display to the user, via the user interface , where to place the imaging device on a patient's body, instruct the imaging device to transmit radiation, receive reflected radiation from the imaging device , process the reflected radiation using machine learning to determine from the reflected radiation whether the imaging device is located correctly relative to a blood vessel of the patient, display to the user, via the user interface , if the imaging device is not located correctly and to reposition the imaging device until the imaging device is correctly located, display to the user, via the user interface , to apply pressure to the patient's blood vessel using the imaging device , instruct the imaging device to transmit further radiation, receive further reflected radiation from the imaging device , and determine from at least the further reflected radiation whether the blood vessel is obstructed. <EOS>