Respiratory motion and its compensation possibilities in the modern external beam radiotherapy of lung cancer

Abstract

The aim of this paper is to present a systematic review of the current characteristics and recent development of commercially available respiratory motion solutions and their compensation possibilities in the external beam radiotherapy treatment of lung cancer. The most commonly used X-ray and radiotherapeutic technologies are presented, as well as their division into pre-treatment methods and intra-treatment verification. The article discusses the most important technological achievements that allow radiation to be safely applied in the lung region and reports the potential advantages and limitations of each. Finally, it presents details concerning selected research trends and problems related to motion compensation. NOWOTWORY J Oncol 2017; 67, 5: 292-296

Tumor tracking using the Radixact system. Review of reports presented at the ESTRO 38 conference in Milan

“…Pod tym kątem pojawiły się nawet wyniki badań, które dla guzów poruszających się w korelacji z kolejnymi fazami cyklu oddechowego raportują podobne objętości guza wyznaczone dla leczenia ze śledzeniem zmian położenia guza (tumor tracking) z jego objętościami leczonymi z bramkowaniem oddechowym (respiratory gating) przy zastosowaniu bardzo krótkiego okna czasowego [12]. Należy w tym miejscu wspomnieć, że pod pojęciem okna czasowego zaszyta jest informacja o przedziale czasowym, w którym pacjent będzie napromieniany, czyli w jakim procencie cyklu oddechowego, z jego całości, promieniowanie będzie dostarczane zgodnie z parametrami przygotowanego wcześniej planu leczenia [2].…”

“…algorytm przewidujący. Ta składowa zbudowanego modelu rekompensuje potencjalne opóźnienia systemowe wynikające z konieczności zebrania i analizy danych dotyczących pozycji guza [2,[12][13][14].…”

Modelling the effects of lung cancer motion due to respiration

“…Apart from interplay, planned dose distribution may not match the actual one due to dose blurring [4]. The effect is limited to this part of the irradiation fi eld where dose gradient occurs, and thus, its impact can be predicted as the weighted average calculated for two paths of dose distribution, with and without breathing motion [8][9][10]. As a typical spatial effect, dose blurring is independent of the delivery technique [5,8].…”

4DCT-based evaluation of lung tumor motion during the breathing cycle

“…For tumors significantly affected by respiratory motion (e.g. lung cancer), the quality of standard three-dimensional computed tomography (3DCT) images may be biased by motion artifacts that influence the size, shape and density of scanned anatomical structures (including the tumor) [1][2][3][4][5][6][7][8]. This degrades a precise determination of tumor dimension and its position and, finally, does not guarantee a safe, accurate and effective external beam dose delivery [9][10][11].…”

“…Thus, respiration is considered not only a major target motion cause, but also one of the biggest uncertainties, which may occur during the whole treatment course and affect not only the target located in the lung but also neighboring organs at risk (OARs) [12][13][14][15]. To manage this problem, several solutions applied to the CT scanning procedure were proposed, including CT scanning with very long scan times per slice (slow CT), CT in breath hold or forced shallow breathing and four-dimensional computed tomography (4DCT) [5,16,17]. The first three options have many limitations.…”