Prostate-bladder phantom for radionuclide imaging research

Radionuclide imaging modalities such as SPECT and PET can play an important role in detecting primary prostate cancer and pelvic lymph node metastasis. However, these imaging techniques are mostly limited by poor spatial resolution and photon detection sensitivity to perform clinical investigations (e.g., ¹¹¹In-capromab pendetide SPECT(/CT) and ¹¹C-choline/acetate PET(/CT)). New hardware or software approaches, often combined with new radionuclide imaging probes, to resolve the issues with the current technology can benefit from a radionuclide phantom that can realistically model prostate, bladder, and lymph nodes in pelvis. In order to make such a phantom, prostate and bladder inserts were designed to fit in the NEMA-IEC body phantom. With the six fillable spheres of various diameters in this body phantom, prostate and bladder inserts replacing the cylindrical lung insert, comprise a prostate-bladder phantom for radionuclide imaging. In addition, the prostate insert is divided into four compartments with two larger compartments simulating normal prostate areas and two smaller compartments simulating lesions within prostate. The spheres model various sizes of lymph nodes and large blood vessels in the pelvis. This custom-made prostate-bladder phantom filled with ^99mTc-pertechnetate in all fillable volumes (prostate, bladder, and spheres) and the body cylinder was imaged with a clinical SPECT/CT scanner (Infinia Hawkeye, GE Healthcare). The activity concentrations were 1:4:7 ([body phantom]:[spheres, bladder, and two larger compartments of prostate]:[two smaller compartments of prostate]) with the total administered activity less than 111 MBq. In the reconstructed SPECT/CT images, all inserts were visible except the two smallest spheres due to the limited spatial resolution of the camera. The prostate-bladder phantom presented in this report can be used in radionuclide imaging experiments that have goals of improving prostate cancer s- - taging by either hardware or software techniques.