**5. Relative dosimetry**

In the clinical environment various measurements are performed under nonreference conditions where the calibration coefficient does not need to be used. These measurements are called relative, such as: dosimetry of other radiation fields (values compared with the reference field, output factors), wedge filter factor (ratio between readings performed with and without filter on the same geometry), measurements of depth dose (normalized to the values obtained at the maximum dose point for that specific radiation field and type of beam).

In these cases, there is a variety of detectors that can be used without compromising on having their values related to the true value of the quantity.

For example: diodes, TLDs, micro-cameras, detector array, alanine, film, MOSFET among others, all of them with their well-defined and different characteristics, such as (sensitivity, short term repeatability, long-term stability, angular, dose rate and energy dependence, detector size, leakage, signal fading) among others must be considered.

## **6. Key points**

Check and consider, if applicable, the following:


Special cases where the reference conditions are not able to follow TRS#398 [1] recommendations are called non-reference conditions. Small fields used in radiosurgery show a more complex spectrum and require ionization chambers with other dimensions, additional geometric conditions, and specific formalism.

In this case, the TRS# 483 [20] should be used as a reference, the most suitable one at this time, where a relatively small variety of detectors are used, generally limited by the field size and the loss of lateral electronic balance.

Replace the entirety of this text with the main body of your chapter. The body is where the author explains experiments, presents, and interprets data of one's research. Authors are free to decide how the main body will be structured. However, you are required to have at least one heading. Please ensure that either British or American English is used consistently in your chapter.

### **7. Conclusion**

This entire chain of measurements and formalism must take into account the specific physical conditions of the interaction processes between the radiation beam with the detector in the measurement processes, aiming to ensure the least possible uncertainty in the dose delivered to the patient.

The different levels of complexity and duties of the metrological stakeholders are a result of the complexity of the experimental arrangements, the quality of the measurement systems, the degree of control over the environmental conditions and the high cost, which makes it not compatible with the clinical environment.

However, the metrological consistency between the different levels guarantees a level of final uncertainty of the dose delivered to the patient compatible with the recommendations of international organizations.

Therefore, if we keep the instruments (electrometer + cable + camera) accompanied by a quality assurance program, with its periodic calibrations and care to maintain its functional integrity, the final quality of the measurements will always be in accordance with the concept of the best practice.
