A fuel container holding structure for detachably holding a fuel container 40 including a nozzle 44 in its front end portion is provided with a front end holding portion 22 for holding the front end portion of the fuel container 40 and a rear end holding portion 28 for holding a rear end portion of the fuel container 40. In particular, immunoglobulin single variable domains are provided against markers of TAMs, and methods using the same for in vivo imaging of tumor cells, as well as cancer diagnostics and therapeutics. In one exemplary embodiment of the present invention, a recentering device is provided which receives a signal from an independent motion direction sensor and enables continuous monitoring of a recentering function, thereby detecting recentering control failures. The hydrostatic tool system may also include a system controller.