## 3 EM Techniques for CH Diagnosis
### X-Ray Fluorescence (XRF) in CH Applications
In [29], XRF is coupled with HSI to investigate the Transfiguration by [PERSON] in the Capodimonte Museum (Naples). The investigation reveals the probably earliest use of stibnite (pigment) and provides insights into the artist's techniques. In [128], [PERSON] presents a Macro-X-Ray Fluorescence (MA-XRF) scanner developed at the Italian Institute of Nuclear Physics Cultural Heritage Network (INFN-CHNet), along with related activities in the cultural heritage field. Figure 10 shows the instrumentation itself, while Figure 11 illustrates it in operation. Figure 10: Typical setup of the MA-XRF scanner developed at INFN-CHNet. (1) the 4-mm thick brass case enclosing the Moxtek MAGNUM® X-ray tube, (2) the white plastic cone surrounding the Amptek XR100 SDD detector, (3) the 300 mm (3X) \(\times\) 200 mm (3Y) \(\times\) 50 mm (3Z) linear stages adopted in this case. (4) the CMOS laser sensor positioning controller, (5) one example of the batteries available. Credit [PERSON] [128]. Licensed under a Creative Commons Attribution 4.0 International License [[http://creativecommons.org/licenses/by/4.0/](http://creativecommons.org/licenses/by/4.0/)]([http://creativecommons.org/licenses/by/4.0/](http://creativecommons.org/licenses/by/4.0/)) (accessed on 20 November 2024). No changes were made to figure but to capture. This scanner has been employed to exploit one great potential of the XRF technique: the recovery of lost images, i.e., hidden pictures. Moreover, the combined use of the scanner with digital radiology (DR) techniques allows the acquisition of details of the support structure of the painting, thanks to the better spatial resolution of DR compared to MA-XRF, which instead reveals the distribution of elements such as Fe, Ca, Pb, and Au. Figure 7 shows the DR result of this combination, while in Figure 12, you can see results obtained in the same detail with the CHNet MA-XRF scanner. Finally, this section includes a comparison of different XRF implementations (WDXRF, EDXRF, micro-XRF), highlighting their strengths and the need for systematic evaluation. This comparison, reported in Table 13, aims to highlight the main types of XRF implementations, their operational principles, advantages, limitations, and typical use cases. The selection of an XRF implementation should be tailored to the specific requirements of the application, including factors such as resolution, sensitivity, portability, and budget constraints. WDXRF provides high-resolution analysis, ideal for laboratory environments, enabling precise elemental detection. EDXRF, on the other hand, offers rapid, on-site testing with enhanced portability, making it suitable for field applications. Micro-XRF extends these capabilities by providing spatially resolved elemental imaging, thereby expanding its range of potential uses. A thorough understanding of these differences enables users to choose the most suitable XRF system to meet their unique analytical needs effectively. Utilizing radiation technologies, such as radiography, radiolysis, and ionizing radiation, is a valuable method for analyzing, conserving, and restoring CH artifacts. However, ensuring radiation safety is essential to protect both preservation staff and the integrity of the artifacts. Proper protocols and dosage management are critical to minimizing radiation exposure risks to personnel, artifacts, and the environment while maintaining the effectiveness of diagnostic and conservation procedures. Table 14 provides a comprehensive overview of radiation safety protocols and dosage considerations, emphasizing best practices to enhance practical applicability across various settings. Figure 11: CHNet MA-XRF scanner (**a**) placed over a custom-made platform used for positioning the scanner over the open book to perform analysis over the chosen folio held vertically thanks to an upside-down U-shape Perspex support. (**b**) in front of Scrivania con Scansia di Pietro Piffetti during measurements. Credit [PERSON] [128].