[en] Biopsy is the standard method for the diagnosis of prostate cancer; however, it is inadequate for the assessment of lymph node invasion. Radionuclide imaging might be useful for both diagnosis and N staging, but it requires high uptake of radiotracers in order to overcome difficulties arising from the anatomy of the region. The aim of this study was to assess whether or not technetium-99m labelled bombesin (^99mTc-BN) scan is able to detect prostate cancer and invasion of pelvic lymph nodes. Ten patients were studied with ^99mTc-BN, transrectal ultrasonography, biopsy, computed tomography and magnetic resonance imaging. All the patients with cancer were operated on. Planar dynamic scintigraphy and single-photon emission tomography (SPET) were performed after administration of 185 MBq ^99mTc-BN. Two patients showed benign adenoma and eight showed cancer at biopsy. The average Gleason's score was 7.5±1.3. ^99mTc-BN dynamic planar scan showed hot spots in the prostatic fossa in two of the eight patients with cancer, both of whom had a prostate-specific antigen level higher than 20 ng/ml. In these patients, high uptake inside the prostatic fossa was detected as early as 1 min after injection, before the arrival of radioactivity in the bladder. True positive SPET scans were obtained in all eight patients with cancer. Invasion of the obturator nodes was detected by SPET in three patients, and in all three was confirmed at surgery. Our preliminary data encourage further studies on the prostate with ^99mTc-BN. If the high sensitivity of ^99mTc-BN SPET is confirmed, this method may play an important role in diagnosing and staging prostate cancer. (orig.)

[en] Ra-dichloride is an alpha-emitting radiopharmaceutical used in the treatment of bone metastases from castration-resistant prostate cancer. Image-based dosimetric studies remain challenging because the emitted photons are few. The aim of this study was to implement a methodology for in-vivo quantitative planar imaging, and to assess the absorbed dose to lesions using the MIRD approach. The study included nine Caucasian patients with 24 lesions (6 humeral head lesions, 4 iliac wing lesions, 2 scapular lesions, 5 trochanter lesions, 3 vertebral lesions, 3 glenoid lesions, 1 coxofemoral lesion). The treatment consisted of six injections (one every 4 weeks) of 50 kBq per kg body weight. Gamma-camera calibrations for "2"2"3Ra included measurements of sensitivity and transmission curves. Patients were statically imaged for 30 min, using an MEGP collimator, double-peak acquisition, and filtering to improve the image quality. Lesions were delineated on "9"9"mTc-MDP whole-body images, and the ROIs superimposed on the "2"2"3Ra images after image coregistration. The activity was quantified with background, attenuation, and scatter correction. Absorbed doses were assessed deriving the S values from the S factors for soft-tissue spheres of OLINDA/EXM, evaluating the lesion volumes by delineation on the CT images. In 12 lesions with a wash-in phase the biokinetics were assumed to be biexponential, and to be monoexponential in the remainder. The optimal timing for serial acquisitions was between 1 and 5 h, between 18 and 24 h, between 48 and 60 h, and between 7 and 15 days. The error in cumulated activity neglecting the wash-in phase was between 2 % and 12 %. The mean effective half-life (T_1_/_2_e_f_f) of "2"2"3Ra was 8.2 days (range 5.5-11.4 days). The absorbed dose (D) after the first injection was 0.7 Gy (range 0.2-1.9 Gy). Considering the relative biological effectiveness (RBE) of alpha particles (RBE = 5), D_R_B_E = 899 mGy/MBq (range 340-2,450 mGy/MBq). The percent uptake of "9"9"mTc and "2"2"3Ra (activity extrapolated to t = 0) were significantly correlated. The feasibility of in vivo quantitative imaging in "2"2"3Ra therapy was confirmed. The lesion uptake of "2"2"3Ra-dichloride was significantly correlated with that of "9"9"mTc-MDP. The D_R_B_E to lesions per unit administered activity was much higher than that of other bone-seeking radiopharmaceuticals, but considering a standard administration of 21 MBq (six injections of 50 kBq/kg to a 70-kg patient), the mean cumulative value of D_R_B_E was about 19 Gy, and was therefore in the range of those of other radiopharmaceuticals. The macrodosimetry of bone metastases in treatments with "2"2"3Ra-dichloride is feasible, but more work is needed to demonstrate its helpfulness in predicting clinical outcomes. (orig.)

[en] The matching between the spectral distribution of the scintillation light from a LaBr₃:Ce crystal and the spectral distribution of the quantum efficiency of a Photomultiplier Tube (PMT) can be characterized by a matching factor whose value depicts, in the range from 0 to 1, the efficiency of PMT for the crystal. A systematic survey of literature was carried out identifying a set of 44 LaBr₃:Ce emission spectra and 11 spectral quantum efficiencies of PMTs, all published in the years 2002-2010. Results showing the values of matching factors calculated for all the spectral combinations are presented and commented upon.

[en] We have realized and tested a new-design compact gamma camera for high resolution SPET (Single Photon Emission Tomography), and small animals' radio-pharmaceutical molecular imaging. The camera is based on a 'continuous' Lanthanum tri-Bromide crystal, and a new Low Energy (LE) collimator. The crystal is interfaced to a 2x2 array of Hamamatsu-H8500 position sensitive photo-multipliers. The lead collimator features parallel hexagonal 1.0 mm holes, 18 mm length, 0.2 mm septa and 10x10 cm² detection area. It was newly designed to fully exploit the high spatial resolution a Lanthanum crystal may provide. To better evaluate its role, we have compared our camera to three other systems with similar crystals and photomultipliers, but employing traditional collimators, either pinhole or parallel. The new camera seems to be complementary to pinhole systems and shows a very attractive trade-off between spatial resolution and detection area.

[en] Radium Ra 223 dichloride (radium-223, Xofigo registered) is the first targeted alpha therapy for patients with castration-resistant prostate cancer and symptomatic bone metastases. Radium-223 provides a new treatment option for this setting, but also necessitates a new treatment management approach. We provide straightforward and practical recommendations for European nuclear medicine centres to optimize radium-223 service provision. An independent research consultancy agency observed radium-223 procedures and conducted interviews with all key staff members involved in radium-223 treatment delivery in 11 nuclear medicine centres across six countries (Germany, Italy, the Netherlands, Spain, Switzerland and the UK) experienced in administering radium-223. The findings were collated and discussed at a meeting of experts from these centres, during which key consensus recommendations were defined. The recommendations cover centre organization and preparation; patient referral; radium-223 ordering, preparation and disposal; radium-223 treatment delivery/administration; and patient experience. Guidance includes structured coordination and communication within centres and multidisciplinary teams, focusing on sharing best practice to provide high-quality, patient-centred care throughout the treatment pathway. These expert recommendations are intended to complement existing management guidelines. Sharing best practice and experience will help nuclear medicine centres to optimize radium-223 service provision and improve patient care. (orig.)

[en] We propose the characterization of a first array of 10×10 Lutetium Yttrium Orthoaluminate Perovskite (LuYAP:Ce) crystals, 2 mm×2 mm×10 mm pixel size, with an innovative assembling designed to enhance light output, uniformity and detection efficiency. The innovation consists of the use of 0.015 mm thick dielectric coating as inter-pixel light-insulators, manufactured by Crytur (Czech Republic) intended to improve crystal insulation and then light collection. Respect to the traditional treatment with 0.2 mm of white epoxy, a thinner pixel gap enhances packing fraction up to 98% with a consequent improvement of detection efficiency. Spectroscopic characterization of the array was performed by a Hamamatsu R6231 photomultiplier tube. A pixel-by-pixel scanning with a collimated "9"9"mTc radioisotope (140 keV photon energy) highlighted a deviation in pulse height close to 3.5% respect to the overall mean value. Meanwhile, in term of energy resolution a difference between the response of single pixel and the array of about 10% was measured. Results were also supported and validated by Monte Carlo simulations performed with GEANT4. Although the dielectric coating pixel insulator cannot overcome the inherent limitations of LuYAP crystal due to its self-absorption of light (still present), this study demonstrated that the new coating treatment allows better light collection (nearly close to the expected one) with in addition a very good uniformity between different pixels. These results confirm the high potentiality of this coating for any other crystal array suited for imaging application and new expectations for the use of LuYAP for PET systems

[en] SPECT systems using pinhole apertures permit radiolabelled molecular spatial resolution, good energy resolution, and high sensitivity are required. We designed what we consider the “optimal” radionuclide detector system for this task. It should allow studying both detection of unstable atherosclerotic plaques and monitoring the effect of therapies. Using mice is particularly challenging in situations that require several intravenous injections of radiotracers, possibly for weeks or even months, in chronically ill animals. Thus, alternative routes of delivering the radiotracer in tail vein should be investigated. In this study, we have performed preliminary measurements of detection of atherosclerotic plaques in genetically modified mice with high-resolution prototype detector. We have also evaluated the feasibility of assessing left ventricular perfusion by intraperitoneal distributions to be imaged in vivo in small animals. Nevertheless, studying cardiovascular diseases in small animal models is very challenging, and in particular, submillimeter delivering of MIBI-Tc in healthy mice.

[en] To combine peripheral blood indices and clinical factors in a prognostic score for metastatic castration-resistant prostate cancer (mCRPC) patients treated with radium-223 dichloride ([${}^{223}$Ra]RaCl${}_2$). Baseline neutrophil-to-lymphocyte ratio (NLR), derived NLR (donor), lymphocyte-to-monocyte ratio (LMR), platelet-to-lymphocyte ratio (PLR), systemic inflammation index (SII), Eastern Cooperative Oncology Group performance status (ECOG PS), Gleason score (GS) group, number of bone metastases, prostate-specific antigen (PSA), alkaline phosphatase (ALP), line of therapy, previous chemotherapy, and the presence of lymphadenopathies were collected from seven Italian centers between 2013 and 2020. Lab and clinical data were assessed in correlation with the overall survival (OS). Inflammatory indices were then included separately in the multivariable analyses with the prognostic clinical factors. The model with the highest discriminative ability (c-index) was chosen to develop the BIO-Ra score. Five hundred and nineteen mCRPC patients (median OS: 19.9 months) were enrolled. Higher NLR, dNLR, PLR, and SII and lower LMR predicted worse OS (all with a p < 0.001). The multivariable model including NLR, ECOG PS, number of bone metastases, ALP, and PSA (c-index: 0.724) was chosen to develop the BIO-Ra score. Using the Schneeweiss scoring system, the BIO-Ra score identified three prognostic groups (36%, 27.3%, and 36.6% patients, respectively) with distinct median OS (31, 26.6, and 9.6 months, respectively; hazard ratio: 1.62, p = 0.008 for group 2 vs. 1 and 5.77, p < 0.001 for group 3 vs. 1). The BIO-Ra score represents an easy and widely applicable tool for the prognostic stratification of mCRPC patients treated with [${}^{223}$Ra]RaCl${}_2$ with no additional costs.