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Ocena parametrów rozkładu dawki dla pacjentek z lewostronnym nowotworem piersi napromienianych techniką VMAT na głębokim wdechu

Pietrzyk Izabela, Szczyrek Zofia, Daniluk Anna

Inżynier i Fizyk Medyczny

2022

Vol. 11, nr 3

247--252

Celem pracy jest dokonanie analizy porównawczej parametrów rozkładu dawki na swobodnym oddechu (ang. Free breathing, FB) i wstrzymanym głębokim wdechu (ang. Deep inspiration breath-hold, DIBH) dla pacjentek z lewostronnym nowotworem piersi napromienianych techniką VMAT. Praca została wykonana w Narodowym Instytucie Onkologii im. Marii Skłodowskiej-Curie – Państwowym Instytucie Badawczym przy ul. Wawelskiej 15 w Warszawie. Analizę parametrów rozkładu dawki przeprowadzono na grupie 30 pacjentek napromienianych na obszar blizny po mastektomii oraz na obszar loży pooperacyjnej. Plany napromieniania wykonane zostały w systemie planowania leczenia Monaco firmy ELEKTA. Porównanie planów leczenia na swobodnym oddechu i wstrzymanym głębokim wdechu wykazało, że pod względem objęcia targetu żadna z technik nie jest wiodąca. Technika DIBH pozwoliła na zmniejszenie dawki w narządach krytycznych, przede wszystkim w sercu, płucu po stronie napromienianej i lewej tętnicy wieńcowej. Uzyskane redukcje średniej dawki średniej wynosiły: 40,5%, 11,2%, 56,6%, odpowiednio dla serca, płuca lewego i lewej tętnicy wieńcowej. Redukcja V20Gy i V5Gy dla serca wyniosła 91,4 i 56,6%. Dla płuca lewego V20Gy i V10Gy zredukowano o 12,9 i 8,1%, a dawkę maksymalną dla lewej tętnicy wieńcowej o 44,3%.

The aim of the study is to perform a comparative analysis of the dose distribution parameters for free breathing (FB) and deep inspiration breath-hold (DIBH) for patients with left- -sided breast cancer irradiated with the VMAT technique. The work was carried out at the Maria Skłodowska-Curie – National Research Institute at Wawelska 15 Street in Warsaw. The analysis of the dose distribution parameters was carried out on a group of 30 patients irradiated on the scar after mastectomy and on the area after breast-conserving surgery. The irradiation plans were made in the Monaco treatment planning system by ELEKTA. A comparison of treatment plans with free breath and deep breath hold showed that none of the techniques was leading in terms of target acquisition. The DIBH technique allowed for dose reduction in organs at risk, mainly in the heart, lung on the irradiated side and left anterior descending. The obtained mean mean dose reductions were: 40,5%, 11,2%, 56,6% for the heart, left lung and left anterior descending, respectively. The reduction of V20Gy and V5Gy for the heart was 91,4 and 56,6%. For the left lung, V20Gy and V10Gy were reduced by 12,9 and 8,1%, and the maximum dose for the left coronary artery by 44,3%.

Dosimetric comparison of deep inspiration breath hold and free breathing technique in stereotactic body radiotherapy for localized lung tumor using Flattening Filter Free beam

Mani K. M., Bhuiyan Md. A., Alam Md. M., Ahmed S., Sumon M. A., Sengupta A. K., Rahman Md. S., Islam Md. S. M. A.

Polish Journal of Medical Physics and Engineering

2018

Vol. 24, Iss. 1

15--24

Aim: To compare the dosimetric advantage of stereotactic body radiotherapy (SBRT) for localized lung tumor between deep inspiration breath hold technique and free breathing technique. Materials and methods: We retrospectively included ten previously treated lung tumor patients in this dosimetric study. All the ten patients underwent CT simulation using 4D-CT free breathing (FB) and deep inspiration breath hold (DIBH) techniques. Plans were created using three coplanar full modulated arc using 6 MV flattening filter free (FFF) bream with a dose rate of 1400 MU/min. Same dose constraints for the target and the critical structures for a particular patient were used during the plan optimization process in DIBH and FB datasets. We intend to deliver 50 Gy in 5 fractions for all the patients. For standardization, all the plans were normalized at target mean of the planning target volume (PTV). Doses to the critical structures and targets were recorded from the dose volume histogram for evaluation. Results: The mean right and left lung volumes were inflated by 1.55 and 1.60 times in DIBH scans compared to the FB scans. The mean internal target volume (ITV) increased in the FB datasets by 1.45 times compared to the DIBH data sets. The mean dose followed by standard deviation (x̄ ± σx̄ ) of ipsilateral lung for DIBH-SBRT and FB-SBRT plans were 7.48 ± 3.57 (Gy) and 10.23 ± 4.58 (Gy) respectively, with a mean reduction of 36.84% in DIBH-SBRT plans. Ipsilateral lung were reduced to 36.84% in DIBH plans compared to FB plans. Conclusion: Significant dose reduction in ipsilateral lung due to the lung inflation and target motion restriction in DIBH-SBRT plans were observed compare to FB-SBRT. DIBH-SBRT plans demonstrate superior dose reduction to the normal tissues and other critical structures.