Preface

Computed tomography (CT) was introduced commercially for the first time by British engineer Godfrey Hounsfield in 1972. Since then, it has become the main imaging modality in hospitals and clinical centers. A CT scan can be used to visualize nearly all parts of the body to diagnose disease or injury as well as to plan medical, surgical, or radiation treatment. Particularly, it is well suited for quickly examining people who may have internal injuries from car accidents or other types of traumas. In addition, CT plays an important role in chest imaging in the current COVID-19 pandemic.

The book consists of five chapters. Chapter 1, by Dr. Reda R. Gharieb, presents the instrumentational basics of CT scanning, a mathematical and simulation review of a CT algorithm called the filtered back projection, in linear- and fan-beams projection, and some medical applications of CT imaging. Chapter 2, by Drs. Ibrahima Niang, Géraud Akpo, Khadidiatou Ndiaye Diouf, and Sokhna Ba, discusses the use of CT in the context of the coronavirus pandemic. It explains the effect of coronavirus on the lungs and how physicians can recognize this effect. Chapter 3, by Drs. Elena Ivanovna Matkevich and Ivan Vasilievich Ivanov presents a study of radiation doses and risk assessment during CT of the chest in COVID-19 patients. Chapter 4, by Dr. Sikandar Shaikh, presents the basics and applications of positron emission tomography (PET), an imaging technology that uses positron emission instead of X-rays. Finally, Chapter 5, by Dr. Anil K. Bharodiya, deals with handling, using different image processing methods, and final CT images for feature extraction in recognition of patterns.

The editor thanks the contributing authors for their efforts and for sharing their research. The editor also thanks and appreciates the service and support received from Author Service Managers Mrs. Dzeni Kalcic, Mrs. Nikolina Pomenic, and Mrs. Zrinka Tomicic at IntechOpen.

Finally, I hope that this book will be a useful resource for readers interested in advancing their knowledge and experience of CT scanning.

> **Reda R. Gharieb** Professor of Biomedical Engineering and Electronics, Assiut University, Assiut, Egypt

#### **Chapter 1**
