Radiotherapy treatment has continued to make huge progress especially after the introduction of MRI guidance systems. Although there are many advantages to this, there are unfortunately still obstacles that researchers are trying to understand more clearly such as the fact that in a high-field MR-linac, a strong magnetic field causes hot and cold dose spots which are better known as electron return effect (ERE). This specific phenomenon causes secondary electrons that enter a region of low density to be redirected back toward a high-density region that in turn creates larger dose into denser tissue. A scientific team has been experimenting with two Fricke gels to address this ERE issue. To learn more about this research, the article explains their process in the experiment and what research findings are showing to improve this issue in further radiotherapy treatments.