Abstract: Single photon emission computed tomography (SPECT) is one of the most important imaging modalities for radionuclide organ imaging. Efficiently acquiring high-quality images is a critical clinical need, directly impacting diagnostic accuracy, patient throughput, and radiation dose optimization. Traditional collimators often require prolonged scan times to achieve sufficient counts and resolution, potentially affecting patient comfort and introducing motion artifacts. Multi-pinhole collimator designs offer a promising pathway by multiplexing multiple projections onto the detector to enhance sensitivity and reduce scan time. Based on dual-detector setup, a novel collimator configuration that is a separated multi-pinhole collimator, was designed for multi-pinhole image acquisition. Unlike integrated designs, the collimator assembly was physically separated from the detector heads in this architecture, offering potential advantages in flexibility, maintainability, and mechanical stability for improved pinhole alignment precision. The design of each system component was detailed to maximize angular sampling and sensitivity gain while managing multiplexing and overlap. To meet the clinical accuracy requirements for this separated collimator system, a dedicated calibration method was designed. This process involved the acquisition of point source data, the comparison of the acquired data against theoretical values to determine system parameter offsets, and the subsequent adjustment of these parameters to achieve the necessary reconstruction accuracy. To further validate the feasibility of the separated collimator system, ECT/CAR/I phantom imaging experiments were conducted. Phantom data were reconstructed using an improved maximum likelihood expectation maximization (MLEM) tomographic reconstruction algorithm. Reorientation algorithms were then applied to generate short-axis, horizontal long-axis, and vertical long-axis views for defect observation. Finally, bull’s-eye analysis was performed to delineate the defect regions within the phantom. Results demonstrate that the system can accurately depict and characterize simulated defects within the phantom, which confirms the fundamental feasibility of obtaining diagnostically relevant images with this novel collimator design in a dual-detector SPECT configuration. Beyond qualitative analysis, the system performance is quantitatively evaluated. Analytically calculated and reconstructed metrics include a reconstructed spatial resolution of 4.89 mm, energy resolutions of 9.12%@140 keV (detector 1) and 9.09%@140 keV (detector 2), and an energy range of 50-400 keV. The corresponding system performance is basically consistent with that of traditional parallel hole collimators. Compared to a traditional parallel-hole collimator, it achieves SPECT images of high diagnostic quality with nearly an 8-fold improvement in acquisition efficiency. This design enables higher image quality with significantly reduced acquisition time, offering enhanced clinical support for high-resolution and high-sensitivity dedicated single-organ SPECT imaging applications such as cardiac, brain, and thyroid examinations.