###### Abstract
Both the electrons generated by the photoelectric effect and Compton scattering contribute to the dose and overall DNA damage. Photons are produced in a LINAC through an X-ray target. As technology advances in the clinical setting, the utilization of imaging for guidance in radiotherapy is becoming increasingly common. The enhanced speed of image acquisition methods enables real-time imaging guidance during radiotherapy. Imaging modalities such as computed tomography (CT) or magnetic resonance imaging (MRI) can be employed for this purpose. When conducting MRI scans, the use of contrast agents becomes crucial. These agents are substances that enhance the contrast and visibility of organs in an image [7]. One emerging area of research focuses on the use of iron oxide as a new contrast agent for MRI. While image-guided radiation therapy (IGRT) continues to evolve, the importance of contrast agents in medical imaging remains significant, making advancements in contrast agents relevant to ongoing imaging research [8; 9]. Gold nanoparticles have gained significant attention in the field of radiotherapy due to their unique properties and potential benefits in enhancing radiotherapy effectiveness [10; 11]. One key reason gold can be used in gold nanoparticle-enhanced radiotherapy is its high atomic number. Gold has a high atomic number (Z = 79), which means it is efficient at absorbing and scattering X-rays and photons, the types of radiation commonly used in radiotherapy. This property allows gold nanoparticles to act as potent radiosensitive by increasing the dose delivered to cancer cells while minimizing the damage to surrounding healthy tissues. Furthermore, gold nanoparticles can be precisely targeted to tumor sites. Their small size and surface modifications enable specific attachment to cancer cells or tumor vasculature, providing a localized accumulation of nanoparticles in the tumor region [12]. This targeted delivery of gold nanoparticles allows for enhanced ra diation dose deposition within the tumor, leading to improved tumor control and reduced side effects. Iron nanoparticles have emerged as important contrast agents for MRI due to their distinct properties and benefits in enhancing imaging capabilities. For example, iron nanoparticles possess a high magnetic moment, making them highly responsive to magnetic fields. This property allows them to generate strong signal changes in MRI, resulting in improved image contrast [13]. When administered as a contrast agent, iron nanoparticles can selectively accumulate in specific tissues or organs of interest, providing enhanced visualization and characterization of these areas during MRI scans. The ability to precisely target and highlight specific regions contributes to improved diagnostic accuracy and treatment planning. Another advantage of iron nanoparticles is their biocompatibility and biodegradability. Iron is a naturally occurring element in the body and plays essential roles in various physiological processes [7]. Consequently, iron nanoparticles are generally well-tolerated and exhibit low toxicity. After their use as contrast agents, iron nanoparticles can undergo degradation and clearance from the body, minimizing potential long-term risks or adverse effects. Iron-gold nanoparticles are designed to accumulate in tumors through a phenomenon known as the enhanced permeability and retention effect (EPR effect) [14]. This effect occurs due to the leaky vasculature present in tumor tissues, allowing the nanoparticles to passively diffuse and concentrate within the tumor environment. Once administered, these nanoparticles will be exposed to radiotherapy. After radiotherapy, the body's natural processes, such as the lymphatic and circulatory systems, play a role in removing the iron-gold nanoparticles from the tumor area. Moreover, some nanoparticles may be taken up by tumor-associated macrophages, further aiding in their clearance from the tumor site.