Methodology of Defining of the Radiation Therapy Components for Various Methods of Patients’ Treating Using Medical Linear Accelerators and Gamma-Therapeutic Devices

One of the main factors affecting the effectiveness of radiation therapy is the constancy of the patient’s position on the treatment table created by immobilization devices of various designs and held throughout the entire irradiation procedure, which guarantees the accuracy of the delivery of the prescribed dose distribution. The purpose of the work was to establish the numerical values of the dominant components of a radiation therapy session for each of the irradiation techniques most commonly used in clinical practice of the radiation therapy.

To determine the numerical values of the components of the radiation therapy session, the authors have measured each component for some clinical cases of patients’ irradiation placed. The patients had been diagnosed with the following malignant tumours: prostate cancer, breast cancer, lung cancer, head and neck tumours. More than 2000 individual measurements have been carried out with the help of such medical linear accelerators as "Clinac", "Unique", "Truebeam", and the gamma-therapeutic apparatus named "Theratron".

The numerical values of the time spent on 3 groups of parameters of an irradiation session were established: the mechanical parameters of the radiation therapy equipment, the functional characteristics of the irradiation systems and the parameters that directly depend on the personnel involved in an irradiation procedure.

According to the measurement results, the flow diagram for the procedures of verifying a patient’s position on the therapeutic table (2 different techniques), preceding their irradiation and the radiation therapy procedures themselves was proposed. It has been shown that a number of session components can run in parallel to each other thus optimizing the time spent by a patient in the treatment room.

Using the obtained values of the time spent on the radiation session parameters it is possible to actualize the mathematical model that will allow the medical physicist to determine in advance the duration of the irradiation session at the stage of treatment planning and choose a radiation therapy technique taking into account the individual parameters of the irradiation session in each particular clinical case.

1. Tarutin I.G., Titovich E.V. Primenenie lineinykh uskoriteley elektronov v vysokotekhnologichnoi luchevoi terapii [The use of linear electron accelerators in hightech radiation therapy]. Minsk: Belarusskaya Navuka Publ., 2015, 175 p.

2. International Commission On Radiation Units And Measurements. Determination of Absorbed Dose in a Patient Irradiated by Beams of X or Gamma rays in Radiotherapy Procedures. Washington, D.C., ICRU, 1976, rep. 24. DOI: 10.1093/jicru/ndh016

3. International Atomic Energy Agency. Design and Implementation of a radiotherapy programme: Clinical, medical physics, radiation protection and safety aspects. Vienna, IAEA, 1998, 97 p.

4. Titovich E.V., Patsiapalau P.A., Piatkevich M.N., Kiselev M.G. [The algorithm for determining timing of radiotherapy session components for different methods of oncology patients irradiation at the stage of radiotherapy planning]. Pribory i metody izmerenii [Devices and Methods of Measurements]. 2017, vol. 8, no. 1, рр. 73–80 (in Russian). DOI: 10.21122/2220-9506-2017-8-1-73-80

5. Sibtain A., Morgan A., MacDougall N. Radiotherapy in Practice. Physics for Clinical Oncology. New York: Oxford University Press, 2012, 276 p.

6. Okeanov A.E. Rak v Belarusi: cifry i fakty. Analiz dannykh Belorusskogo kancer-registra za 2009–2018 gg. [Cancer in Belarus: figures and facts. Analysis of the data of the Belarusian Oncological Register for 2009–2018]. Minsk, Nacionalnaya biblioteka Belarusi, 2019, 422 p.

7. Xia Ping, Godley Andrew et al. (eds.) Strategies for radiation therapy treatment planning. Demos Medical Publishing, 2019, 319 p.

8. Khan F.M., Gibbons J.P. Khan’s the physics of radiation therapy, 5th ed. Philadelphia: Wolters Kluwer, 2014, 584 p.

9. Podgorsak E.B. Radiation Physics for Medical Physicists, 2nd ed. Montreal: Springer, 2010, 759 p.

10. Dyk J.V. ACompendium for Medical Physicists and Radiation Oncologists: in 2 v. Madison: MPP, 2005, vol. 2: The modern Technology of Radiation Oncology, 491 p.