The teaching of physics in secondary schools has not been able to follow the technological advances that took place in the last decades and has proved to be farther from student's reality than ever. Obsolete and out of context programs represent a problem to teachers and students, turning teaching and learning into a tedious and uninteresting experience for those involved in the process. Many researches have been carried out with the objective of developing strategies that can promote motivation and dialogues in science classes, specifically in physics. One of the most outstanding trends has been to introduce modern physics topics in secondary school curriculum. The present paper aims at presenting the results of a research on public and private school teachers regarding the introduction of modern physics topics in secondary classrooms. Based on the research results, we have developed a methodology to teach about X-ray by emphasizing its scientific, technologic and social aspects (STS). We have submitted the present text to our peers and have obtained very good results in terms of the acceptance of and readiness to adopt the material.