## 3 EM Techniques for CH Diagnosis
### Infrared Spectroscopy (IRS) and Raman Spectroscopy in CH Applications  
IRS quanta of electromagnetic radiation interact with organic and inorganic compounds. [PERSON] specifies that IRS is mainly used for organic compounds since, sometimes, inorganic compounds do not produce \"definitive spectra\" [89] (p. 33). In fact, as we will see in this section, IRS has been applied in several cases to investigate the presence of organic materials. However, according to [PERSON] et al., IRS is well suited for both organic and inorganic compounds [99].  
IRS spectroscopy can be divided into two main groups, depending on the region of the spectrum considered:  
* mid-infrared (MIR) spectroscopy;
* near-infrared (NIR) spectroscopy.  
Data are generally produced using Fourier transform processing; this is why the technique is frequently referred to as Fourier Transform Infrared Spectroscopy (FTIR). Similar to XRF, data consist of plots of intensity against frequency (or wavelength), where peaks represent types of bonds.  
IR spectroscopy requires samples and can be very destructive, especially in the case of reflectance spectroscopy, which requires the sample to be powdered for the reflectance spectra study. However, modern techniques allow reflectance spectroscopy to be performed without sampling, although the results obtained are highly dependent on the specimens. Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) requires only small quantities of powdered specimens [99].  
Raman spectroscopy provides information that is complementary to IRS. It works very well on inorganic materials such as mineral pigments. Analysis can often be performed in situ, and the data consist of a spectrum of intensity against frequency or wavelength,  
\begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt}} \hline \hline \multicolumn{2}{c}{**Fundamental Principles of Radiation Safety**} \\ \hline Justification: & Ensuring that the benefits of exposure outweigh the risks. No unnecessary exposure should occur. \\ \hline Optimization (ALARA): & As Low As Reasonably Achievable—minimize exposure to the lowest possible levels while achieving the required outcome. \\ \hline Dose Limitation: & Setting dose limits for occupational and public exposures to prevent deterministic effects and reduce stochastic risks. \\ \hline \multicolumn{2}{c}{**Radiation Safety Protocols**} \\ \hline Training and Education: & Regular training sessions for staff on radiation principles, safety measures, and emergency procedures. \\ \hline Authorization and Screening: & Credentialing personnel authorized to operate radiation equipment; screening for pregnancy among female staff. \\ \hline Procedure Justification: & Ensuring each procedure is clinically justified based on patient needs and alternative methods. \\ \hline \multicolumn{2}{c}{**Engineering Controls**} \\ \hline Shielding: & Use of lead aprons, barriers, and room shielding to reduce scattered radiation exposure. \\ \hline Distance: & Maximizing distance from radiation sources—exposure decreases with the square of the distance. \\ \hline Equipment Design: & Utilizing modern, well-maintained equipment with built-in safety features such as exposure timers and interlocks. \\ \hline Personal Protective Equipment (PPE): & \\ \(\bullet\) Lead aprons, thyroid shields, lead glasses, and gloves for staff. \\ \(\bullet\) Properly fitted PPE to ensure maximum protection. \\ \hline \hline \end{tabular}
\end{table}
Table 14: Cont.  
with peaks representing types of chemical bonds. Raman spectroscopy is frequently used in combination with XRF, SEM, and PIXE [133].