An ultrasound device for internal use, comprising: a transducer for emitting and receiving an ultrasound beam, the beam adapted to rotate around at least a portion of the device; a housing containing the transducer and the housing comprising a wall surrounding the transducer, the wall having an inner surface generally facing the transducer and an outer surface generally facing away from the transducer, the wall defining an acoustically transparent acoustic window; wherein at least part of the ultrasound beam passes through the wall wherein the wall has a first portion with a thin metal film placed on the interior of the wall the thin metal film having high electrical conductivity and allowing transmission of an ultrasound beam and a second portion, wherein the thin metal film is used as conductor for the transducer and further wherein the first portion affects the ultrasound beam in a first fashion and the second portion affects the ultrasound beam in a second fashion and wherein the ultrasound beam as it rotates at least periodically travels along a path between the first portion and the transducer and wherein the ultrasound beam as it rotates at least periodically travels along a path between the second portion and the transducer, so that the ultrasound attenuation of the ultrasound beam travelling through the first portion of the wall is different from the ultrasound attenuation of ultrasound beam travelling through the second portion of the wall; and an ultrasound control system electronically connected to the transducer for receiving and assessing electronic signals from the transducer, the electronic signals representing one or more qualities of ultrasound energy that has traveled along the path of the beam, wherein a first electronic signal received by the transducer represents an ultrasound beam travelling through the first portion of the wall and the thin metal film and a second electronic signal received by the transducer represents an ultrasound beam travelling through the second portion of the wall, wherein the ultrasound control system is adapted to detect the difference between the first and second signals and to register a plurality of the electronic signals with each other by reference to the difference. a transducer for emitting and receiving an ultrasound beam, the beam adapted to rotate around at least a portion of the device; a housing containing the transducer and the housing comprising a wall surrounding the transducer, the wall having an inner surface generally facing the transducer and an outer surface generally facing away from the transducer, the wall defining an acoustically transparent acoustic window; wherein at least part of the ultrasound beam passes through the wall wherein the wall has a first portion with a thin metal film placed on the interior of the wall the thin metal film having high electrical conductivity and allowing transmission of an ultrasound beam and a second portion, wherein the thin metal film is used as conductor for the transducer and further wherein the first portion affects the ultrasound beam in a first fashion and the second portion affects the ultrasound beam in a second fashion and wherein the ultrasound beam as it rotates at least periodically travels along a path between the first portion and the transducer and wherein the ultrasound beam as it rotates at least periodically travels along a path between the second portion and the transducer, so that the ultrasound attenuation of the ultrasound beam travelling through the first portion of the wall is different from the ultrasound attenuation of ultrasound beam travelling through the second portion of the wall; and an ultrasound control system electronically connected to the transducer for receiving and assessing electronic signals from the transducer, the electronic signals representing one or more qualities of ultrasound energy that has traveled along the path of the beam, wherein a first electronic signal received by the transducer represents an ultrasound beam travelling through the first portion of the wall and the thin metal film and a second electronic signal received by the transducer represents an ultrasound beam travelling through the second portion of the wall, wherein the ultrasound control system is adapted to detect the difference between the first and second signals and to register a plurality of the electronic signals with each other by reference to the difference.