Topometry is an integral part of irradiation whose task is to repeat the position of the patient set by the simulator to repeat the PTV and the spatial relationship between the radiation field and the risk organs that were identified during planning. The dose distribution formulated in the plan is only an ideal model. There is some gap between the actual and planned dose distribution, especially in overweight patients.
Objective: evaluate the effect of anthropometric data on the deviation between the planned dose and the results of dosimetry in vivo in patients with uterine cancer during postoperative irradiation.
Materials and methods: The authors analyzed the results of treatment of 110 patients with stage IB-II uterine can- cer who were treated at the Department of Radiation Therapy of the Institute of Medical Radiology and Oncology of the National Academy of Medical Sciences of Ukraine from 2016 to 2019. The technique of classical fractionation was used with a single focal dose of 2.0 Gy 5 times a week, the total focal dose was 42.0-50.0 Gy. To assess the effect of the patient's anthropometric data on the difference between the actual and calculated dose, the authors per- formed in vivo dosimetry after the first session and in the middle of the postoperative course of external beam radi- ation therapy.
Results: Рatients with BSA < 1.92 m2, had the median relative deviation at the first session -4.12 %, after 20.0 Gy - 3.61 %, patients with BSA > 1.92 m2: -2.06 % and -1.55 % respectively. After 20 Gy 34.8 % of patients with BSA < 1.92 m2 there was an increase in deviation from the planned dose, 65.2 % a decrease, while in 56.1 % of patients with BSA > 1.92 m2 there was an increase, and in 43.9 % - its reduction. With increasing BMI, the actual dose received on the rectal mucosa in the tenth session of irradiation is approaching the calculated one.
Conclusions: When irradiated on the ROKUS-AM device, we did not find a probable dependence of the influence of the constitutional features of patients between the received and planned radiation dose. When treated with a Clinac 600 C, only body weight and body mass index at the tenth irradiation session have a likely effect on the dose differ- ence. Therefore, issues related to the individual approach to the treatment of uterine cancer, depending on anthro- pometric data is an urgent problem of modern radiotherapy.
Peredpromeneva topometriia ie nevid’iemnoiu chastynoiu oprominennia, zavdannia iakoï – vidtvoryty polozhennia patsiientky, zadane symuliatorom, shchob vykonaty zaplanovanyĭ ob’iem oprominennia i prostorovi vidnosyny mizh po- lem vyprominiuvannia ĭ organamy ryzyku, iaki buly vyznacheni pid chas planuvannia. Rozpodil dozy, sformul'ova- nyĭ u plani, ie lyshe ideal'noiu modelliu. Isnuie deiakyĭ rozryv mizh faktychnym i zaplanovanym rozpodilom dozy, osoblyvo u patsiientok z nadmirnoiu masoiu tila. Metoiu doslidzhennia bulo otsinyty vplyv antropometrychnykh danykh na vidkhylennia mizh zaplanovanoiu dozoiu i re- zul'tatamy dozymetriï in vivo u patsiientok, khvorykh na rak tila matky, pry provedenni pisliaoperatsiĭnogo op- rominennia. Materialy ta metody. Avtory proanalizuvaly rezul'taty likuvannia 110 khvorykh na RTM stadiĭ IB–II, iaki prokho- dyly likuvannia u viddilenni promenevoï terapiï DU «Instytut medychnoï radiologiï ta onkologiï im. S.P. Grygor’ieva NAMN Ukraïny» z 2016 po 2019 roky. Vykorystovuvaly metodyku klasychnogo fraktsionuvannia z razovoiu osered- kovoiu dozoiu 2,0 Gr 5 raziv na tyzhden', sumarna oseredkova doza sklala 42,0–50,0 Gr. Dlia otsinky vplyvu antro- pometrychnykh danykh patsiientok na riznytsiu mizh faktychnoiu i rozrakhunkovoiu dozoiu avtory provely dozymetriiu in vivo pislia pershogo seansu i v seredyni pisliaoperatsiĭnogo kursu dystantsiĭnoï promenevoï terapiï. Rezul'taty. U patsiientok iz ploshcheiu poverkhni tila (PPT) < 1,92 m2 mediana vidnosnykh vidkhylen' na pershomu se- ansi sklala -4,12 %, pislia oprominennia v dozi 20,0 Gr – 3,61 %, a u patsiientok z PPT > 1,92 m2 : -2,06 %, ta -1,55 % vidpovidno. Pislia otrymannia dozy v 20 Gr u 34,8 % patsiientok z PPT < 1,92 m2 vidmichalosia zrostannia vidkhylennia vid zaplanovanoï dozy, u 65,2 % – zmenshennia, todi iak u 56,1 % patsiientok z PPT > 1,92 m2 – zrostannia pokaznyka, a u 43,9 % – ĭogo zmenshennia. Zi zbil'shenniam indeksu masy tila faktychno otrymana doza na slyzovu priamoï kysh- ky na desiatomu seansi oprominennia nablyzhuiet'sia do rozrakhunkovoï. Vysnovky. Pry oprominenni na aparati ROKUS-AM avtory ne vyiavyly virogidnoï zalezhnosti vplyvu konsty- tutsional'nykh osoblyvosteĭ patsiientok mizh faktychno otrymanoiu i zaplanovanoiu dozoiu oprominennia. Pry liku- vanni na aparati Clinac 600 S virogidnyĭ vplyv na riznytsiu doz maiut' til'ky masa tila ta indeks masy tila na de- siatomu seansi oprominennia. Tomu pytannia, shcho stosuiut'sia indyvidual'nogo pidkhodu do likuvannia raku tila matky zalezhno vid antropometrychnykh danykh ie aktual'noiu problemoiu suchasnoï radioterapiï.
Keywords: anthropometric data; in vivo dosimetry; obesity; preradiation preparation; radiation therapy; uterine cancer.
O. M. Sukhina, A. S. Simbirova, V. S. Sukhin.