Objective. To measure the monoenergetic x-ray linear attenuation coefficient, μ , of fused deposition modeling (FDM) colored 3D printing materials (ABS, PLA _white , PLA _orange , PET and NYLON), used as adipose, glandular or skin tissue substitutes for manufacturing physical breast phantoms. Approach . Attenuation data (at 14, 18, 20, 24, 28, 30 and 36 keV) were acquired at Elettra synchrotron radiation facility, with step-wedge objects, using the Lambert–Beer law and a CCD imaging detector. Test objects were 3D printed using the Ultimaker 3 FDM printer. PMMA, Nylon-6 and high-density polyethylene step objects were also investigated for the validation of the proposed methodology. Printing uniformity was assessed via monoenergetic and polyenergetic imaging (32 kV, W/Rh). Main results . Maximum absolute deviation of μ for PMMA, Nylon-6 and HD-PE was 5.0%, with reference to literature data. For ABS and NYLON, μ differed by less than 6.1% and 7.1% from that of adipose tissue, respectively; for PET and PLA _orange the difference was less than 11.3% and 6.3% from glandular tissue, respectively. PLA _orange is a good substitute of skin (differences from −9.4% to +1.2%). Hence, ABS and NYLON filaments are suitable adipose tissue substitutes, while PET and PLA _orange mimick the glandular tissue. PLA _white could be printed at less than 100% infill density for matching the attenuation of glandular tissue, using the measured density calibration curve. The printing mesh was observed for sample thicknesses less than 60 mm, imaged in the direction normal to the printing layers. Printing dimensional repeatability and reproducibility was less 1%. Significance . For the first time an experimental determination was provided of the linear attenuation coefficient of common 3D printing filament materials with estimates of μ at all energies in the range 14–36 keV, for their use in mammography, breast tomosynthesis and breast computed tomography investigations.

The aim of the present study was to evaluate the safety and efficacy of radionuclide therapy with [¹⁷⁷Lu]Lu-DOTA-TATE according to our single center experience at the University of Naples Federico II. For the present analysis, we considered 21 patients with progressive, advanced, well-differentiated G1 and G2 in patients with gastro-entero-pancreatic (GEP) neuroendocrine tumors (NETs) treated with [¹⁷⁷Lu]Lu-DOTA-TATE according to the decisions of a multidisciplinary team. All patients underwent four cycles of 7–8 GBq of [¹⁷⁷Lu]Lu-DOTA-TATE every 8 weeks. A whole-body scan (WBS) was performed 4, 48, and 168 h after each treatment. The dosimetry towards the organ at risk and target lesions was calculated. For each patient, renal and bone marrow parameters were evaluated before, during, and 3 months after the end of the treatment. Follow-up data were obtained and RECIST criteria were considered as the endpoint. Among 21 patients enrolled (mean age 65 ± 9 years); 17 (81%) were men and the small intestine was the most frequent location of disease (n = 12). A mild albeit significant variation (p < 0.05) in both platelets and white blood cell counts among all time points was observed, despite it disappearing 3 months after the end of the therapy. According to the RECIST criteria, 11 (55%) patients had a partial response to therapy and 8 (40%) had stable disease. Only one (5%) patient had disease progression 4 months after treatment. Our data confirm that [¹⁷⁷Lu]Lu-DOTA is safe and effective in controlling the burden disease of G1/G2 GEP-NETs patients.

Objective. We present a method for personalized organ dose estimates obtained before the computed tomography (CT) exam, via 3D optical body scanning and Monte Carlo (MC) simulations. Approach. A voxelized phantom is derived by adapting a reference phantom to the body size and shape measured with a portable 3D optical scanner, which returns the 3D silhouette of the patient. This was used as an external rigid envelope for incorporating a tailored version of the internal body anatomy derived from a phantom dataset (National Cancer Institute, NIH, USA) matched for gender, age, weight, and height. The proof-of-principle was conducted on adult head phantoms. The Geant4 MC code provided estimates of the organ doses from 3D absorbed dose maps in the voxelized body phantom. Main results. We applied this approach for head CT scanning using an anthropomorphic voxelized head phantom derived from 3D optical scans of manikins. We compared the estimates of head organ doses with those provided by the NCICT 3.0 software (NCI, NIH, USA). Head organ doses differed up to 38% using the proposed personalized estimate and MC code, with respect to corresponding estimates calculated for the standard (non-personalized) reference head phantom. Preliminary application of the MC code to chest CT scans is shown. Real-time pre-exam personalized CT dosimetry is envisaged with adoption of a Graphics Processing Unit-based fast MC code. Significance. The developed procedure for personalized organ dose estimates before the CT exam, introduces a new approach for realistic description of size and shape of patients via voxelized phantoms specific for each patient.

To characterize the image quality and dose level of a cone-beam CT (CBCT) scanner dedicated to maxillo-facial intra-surgical navigation. Acquisition protocols for head imaging of average pediatric and adult patients were investigated. The detector response curve and the modulation transfer function (MTF) were assessed. The 3D image quality was evaluated using a commercial Catphan604 phantom in terms of accuracy of Hounsfield Unit (HU) estimates and slice uniformity. The MTF and the noise power spectrum (NPS) were assessed over the 3D reconstructed images. The weighted cone-beam dose index (CBDI_w) was used for dosimetric benchmarking, and TLD chips placed in two anthropomorphic phantoms provided insight into the patient dose distribution. The detector exhibited a response curve with a double natural logarithmic behavior and spatial resolutions up to 6.3 mm^-1. The 3D spatial resolution ranged from 0.70 mm^-1 at the scanner isocenter, for the pediatric protocol, to 0.46 mm^-1 at 7 cm from the isocenter for the adult protocol. Due to beam hardening and the scatter, discrepancies between expected and measured HU were observed, in particular for positive HU values (i.e. those for acrylic, bone, delrin and teflon inserts). The CBDI_w and dose distribution within anthropomorphic phantoms provided a dosimetric benchmark for the scanner. This study characterized a CBCT scanner in maxillo-facial surgery navigation. The findings support the definition of quality assurance protocols, providing methodologies and reference values for image quality and dose, while also highlighting limitations in spatial resolution and accuracy relevant for quantitative evaluations in clinical practice.