Getter multilayer structures are disclosed, embodiments of which include at least a layer of a non-evaporable getter alloy having a low activation temperature over a layer of a different non-evaporable getter material having high specific surface area, both preferably obtained by cathodic deposition. The bias circuit includes: a reference voltage terminal into which a reference voltage is input; a power terminal connected to a power source; a transistor having a control terminal connected to the reference voltage terminal, a first terminal connected to the power terminal, and a second terminal that is grounded. An actual image acquisition means 6 acquires a 3-D actual image of the part of the phantom which is filled with the radioactive material. The lower level node includes switches, wherein the switches are operated to establish a channel between the root node and a selected one of the patch sensors and wherein actuator signal or sensor signal is transmitted through the channel.