THE ALGORITHM FOR DETERMINING TIMING OF RADIOTHERAPY SESSION COMPONENTS FOR DIFFERENT METHODS OF ONCOLOGY PATIENTS IRRADIATION AT THE STAGE OF RADIOTHERAPY PLANNING

One of the main factors affecting the efficiency of oncology patients radiation therapy are time parameters (the amount of time that a patient spends in the therapy room) of the patient exposure session, because the patient treatment position depends on them, and thus the accuracy of delivery of the prescribed dose distribution too. The objective of this work was to define components that influence on the treatment session and to develop an algorithm that allows to determine the duration of the patient treatment sessions with the use of different methods of radiotherapy and tumor localization.

In order to determine radiation therapy session components, that cause the dominant influence on the session timing, the authors carried out a retrospective analysis of each fraction of the total sample of cancer patients treatment plans with most often irradiated with the use of linear accelerators in the NCCB localizations of tumors (more than 5200 fractions).

The appropriate algorithms were designed to assess the results of the analysis of time parameters of radiation therapy oncology patient session during its pre-radiation preparation. It allowed to take into account the individual characteristics of radiation treatment for each irradiation techniques that are the most useful in clinical practice of NCCB radiotherapy department.The components of radiation therapy sessions that caused dominant influence on session characteristics using methods of three-dimensional conformal radiation therapy (3D CRT), intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) were identified.

The characteristics of the linear accelerator and the irradiation plan that influenced the duration of these components (number of radiation fields, dose affecting devices placement, treatment table rotation, treatment field irradiation duration, verification of patient positioning, treatment parameters initialization) were defined. Average exposure time is established for each of the examined methods of radiotherapy and localizations of tumor (from 4 to 8 min for 3D CRT, from 4 to 8 min for IMRT for 3 to 4 min for VMAT). 

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