**Abstract**

The clinical specialty of radiotherapy is an essential part of the multidisciplinary process of treatment of malignant neoplasms. Modern radiotherapy is a very complex process of treatment planning and delivery of radiation dose. Radiotherapy reached a very high degree of complexity and sophistication and expected to represent an added value for the cancer patients in terms of clinical outcomes and improved radiation protection. The concept of verifying the realized dose in the medical applications of ionizing radiation was introduced in the early 20th century shortly after the first application of X-rays for the treatment of cancer. Dosimetry audit identify areas for improvement and provide confidence in safety and efficacy, which are essential to creating a clinical environment of continuous development and improvement. Over the years, the audits have contributed to good dosimetry practice and accuracy of dose measurements in modern radiotherapy. Dosimetry audit ensures, that the correct therapeutic dose is delivered to the patients undergoing radiotherapy and play a key role in activities to create a good radiation protection and safety culture. Patient safety is of paramount importance to medical staff in radiotherapy centers and safety considerations are an element in all aspects of the day-to-day clinical activities.

**Keywords:** modern radiotherapy, clinical audit, dosimetry audit, radiation dosimetry measurements, radiophotoluminescent dosimeters (RPLD), quality assurance, quality managemnet

### **1. Introduction**

The clinical specialty of radiotherapy is an essential part of the multidisciplinary process of treatment of malignant neoplasms. Moreover, oncological diseases are and will continue to be a growing health - social and socio - economic problem nationally and globally in the coming decades. The development of the clinical method of radiotherapy is based on advances in nuclear and information technology. In recent years, dramatic and I would say revolutionary changes have taken place in connection with the introduction into routine practice of a number of new methods and radiotherapy techniques for delivering of the therapeutic dose. All these innovations, set the requirements for the development of precise and clear rules, criteria and standards for the quality of the radiotherapy process as well as for conducting a regular dosimetric quality audit. Clinical audit is defined as a process of quality improvement that seeks to improve patient care and outcomes by systematically reviewing the clinical activity performed against certain formulated criteria [1].

#### *Radiation Oncology*

The quality audit in radiotherapy is an independent review of the quality assurance programs, which is ideally external to the process or part of the process being audited, ie. it is performed through independent procedures and by independent staff, who are not responsible for the performance of the activities, that are the subject of the audit.

The purpose of the introduction and development of the concept of external audit in the radiotherapy is to create and maintain a consistently high quality of the treatment method. The external audit ensures, that the clinical requirements for the quality of radiotherapy are met to achieve optimal treatment in terms of maximizing the likelihood of tumor control, while maintaining low normal tissue damage within clinically acceptable levels. As part of this, the implementation of a quality assurance program will minimize errors and incidents. Most countries seek to establish transparent quality management systems in health care for a number of reasons professional, social, financial and political. The main goal of this form of quality assurance (QA) is to improve patient care with the intention of maximizing the effect of clinical activities, minimizing harm to the individual and society as a whole.

Achieving high quality in clinical practice in general and in radiation therapy in particular is a fundamental goal. The effectiveness of the clinical method of radiotherapy depends on the exact reproducibility of the patient's position, the technical parameters of the irradiation systems and the exact dosimetric calibration of the used photon or electron beams of radiation, which are subject to international standards. The technical achievements and the conducted clinical studies impose the need of quality control programs and respectively external dosimetric audit of the radiation therapy process. This has led to the development and publication of a large number of international recommendations. The aim is to provide reliable, effective and precise radiation therapy. One of the key element is the organization and conducting of dosimetry audit in modern radiation therapy.

### **2. Modern radiotherapy**

Cancer is a leading cause of death worldwide, accounting for nearly 10 million deaths in 2020. The most common in 2020 (in terms of new cases of cancer) are: breast (2.26 million cases); lung (2.21 million cases); colon and rectum (1.93 million cases); prostate (1.41 million cases); skin (non-melanoma) (1.20 million cases) and stomach (1.09 million cases) [2]. Radiotherapy is recognized as an essential element of an effective cancer care program throughout the world. It is vital component of the treatment of cancer for many years. Aproximatelly half of all cancer patients requiring a radiotherapy in some time of their deceases. Abdel-Wahab et al. [3], Barton et al. [4], and Atun et al. [5], argue, that radiotherapy is a critical and costeffective component of a comprehensive cancer control plan [6].

Modern radiotherapy is a very complex process of treatment planning and delivery of radiation dose. Today, radiotherapy encompasses a lot of steps from clinical evaluation to posttreatment follow-up. The clinical process of modern radiation therapy starts with a therapeutic decision at the first appointment with cancer patient, where the radiation oncologist prescribes the radiotherapy treatment. Then the immobilization of patient is performed, which be adopted during treatment. A computerized tomography (CT) scan of the patient is acquired for delineations of the planning target volumes (PTV) and the organs-at-risk (OARs). The CT images may be fusion with other imaging modalities such as magnetic resonance imaging (MRI) and positron emission tomography (PET) for the precise determination of PTV and OARs. A treatment plan is created on a treatment planning system (TPS) based on the outlined structures and on the dose prescription to the PTV and

#### *Dosimetry Audit in Modern Radiotherapy DOI: http://dx.doi.org/10.5772/intechopen.100941*

tolerance dose criteria to the OARs. A pre-treatment quality assurance (QA) verification of the treatment plan has been performed after its evaluation and approving by the radiation oncologist. Image guided radiation therapy (IGRT) modality is using to check patient positioning before each treatment.

In recent years, radiotherapy has been advancing toward achieving a higher cure rate with a higher therapeutic dose and minimum side-effects. This has been possible through the development of high-performance and highprecision radiotherapy techniques and by applying cutting-edge medical technologies [7].

Modern radiotherapy reached a very high degree of complexity and sophistication and expected to represent an added value for the cancer patients in terms of clinical outcomes and improved radiation protection.

In 2016, IAEA published a new guidance document titled: Accuracy Requirements and Uncertainties in Radiotherapy [8]. All forms of radiotherapy should be applied as accurately as reasonably achievable with technical and biological factors being considered, but that regular independent dosimetry audit be conducted using postal (remote) or on-site visits [9].
