Medical Radiology and Radiation Safety. 2025. Vol. 70. № 5
DOI:10.33266/1024-6177-2025-70-5-104-108
I.M. Lebedenko1, 2, E.O. Sannikova1, E.N. Shastina2, E.S. Rannev1
Assessment of the Uniformity of Dose Distribution in the Patient’s Body During Total Irradiation
1 N.N. Blokhin National Medical Research Center of Oncology, Moscow, Russia
2 National Research Nuclear University MEPhI, Moscow, Russia
Contact person: I. M. Lebedenko, e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
ABSTRACT
Purpose: To evaluate the uniformity of dose distribution in the target (throughout the patient’s body) for 39 sick children during total body irradiation.
Material and methods: Total body irradiation (TBI) of 39 children with lymphoblastic leukemia was performed on the Clinac iX electron accelerator (Varian) with a photon radiation 6 MV. The field size at the diaphragm was 40 × 40 cm. The patient’s position from the isocenter of the accelerator is 550 cm. The single dose is 1,0 Gy, the total dose is 12,0 Gy. The number of fractions is 6. Irradiation was carried out behind plexiglas with protective cerrobend blocks on the lungs. To ensure uniformity of dose distribution, boluses of tissue-equivalent material were used.
The dose rate is low and ranges from 0,05 to 0,10 Gy/min, the calculation of irradiation plans is performed on the Eclipse (Varian) planning system. Irradiation is performed with two opposite wide fields with the patient in the lying on the right side position on the therapeutic table. Vacuum mattresses are used as a patient fixation device. A quantitative analysis of patient irradiation plans was carried out using dose–
volume histograms with the use of the homogeneity index HI and assessments of dose loads on critical structures (heart, lungs, kidneys, eye lenses).
Results: It is shown that for 96 % of patients, doses in all organs are distributed uniformly within a tolerance of 10 %, a similar picture is observed for a tolerance of 15 %. The dose homogeneity of the HI dose distribution within the target volume was estimated with and without taking into account boluses. In the presence of boluses, the average value of the homogeneity index HI is lower than in their absence. This means that the use of tissue-equivalent boluses contributes to an increase in the homogeneity of dose distribution and is absolutely justified.
Keywords: radiotherapy, children, total body irradiation, quantitative dose uniformity analysis
For citation: Lebedenko IM, Sannikova EO, Shastina EN, Rannev ES. Assessment of the Uniformity of Dose Distribution in the Patient’s Body During Total Irradiation. Medical Radiology and Radiation Safety. 2025;70(5):104–108. (In Russian). DOI:10.33266/1024-6177-2025-70-5-104-108
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PDF (RUS) Full-text article (in Russian)
Conflict of interest. The authors declare no conflict of interest.
Financing. The work was carried out with the support of the NRC MEPhI Competitiveness Enhancement Program (Contract No. 02.a03.21.0005).
Contribution. M. Lebedenko: development of the research concept, writing of the article; E.O. Sannikova: selection of clinical material; E.N. Shastina: selection of clinical material, data processing, and drawing; E.S. Rannev: management of patients, outlining of critical structures.
Article received: 20.05.2025. Accepted for publication: 25.06.2025.