A Laue lens is an ensemble of crystals capable of focusing, through diffraction in transmission geometry, a fraction of the photons emitted by an X- or γ-ray source onto a small area of a detector. The present study facilitates a thorough understanding of the effect of each system parameter on the efficiency, the resolution and the field of view of the lens. In this way, the structure and the size of the crystals can be set to achieve a compact lens capable of providing a high-resolution image of the radioactivity distribution lying inside a restricted region of a patient's body. As an application, a Laue lens optimized at 140.5 keV, the γ-line emitted by^99mTc, has been designed. The lens is composed of ten rings of Ge crystals with curved diffracting planes and focuses the photons onto a detector 50 cm apart from the source with 1.16 × 10⁻⁵efficiency and 0.2 mm resolution. The combination of these two important figures of merit makes the proposed device better performing than pinhole single photon emission computed tomography, which is the technique employed for top-resolution images in nuclear medicine. Finally, the imaging capability of the designed lens has been tested through simulations performed with a custom-made Monte Carlo code.