Considerable pancreatic tumor motion during breath-holding

Abstract

Background: Breath-holding (BH) is often used to reduce abdominal organ motion during radiotherapy. However, for inhale BH, abdominal tumor motion during BH has not yet been investigated. The aim of this study was to quantify tumor motion during inhale BH and tumor position variations between consecutive inhale BHs in pancreatic cancer patients. Material and methods: Twelve patients with intratumoral fiducials were included and asked to perform three consecutive 30-second inhale BHs on each of three measurement days. During BH, lateral fluoroscopic movies were obtained and a two-dimensional (2D) image correlation algorithm was used to track the fiducials and the diaphragm, yielding the tumor and diaphragm motion during each BH. The tumor position variation between consecutive BHs was obtained from the difference in initial tumor position between consecutive BHs on a single measurement day. Results: We observed tumor motion during BH with a mean absolute maximum displacement over all BHs of 4.2 mm (range 1.0-11.0 mm) in inferior-superior (IS) direction and 2.7 mm (range 0.5-8.0 mm) in anterior-posterior (AP) direction. We found only a moderate correlation between tumor and diaphragm motion in the IS direction (Pearson's correlation coefficient jrj>0.6 in 45 of 76 BHs). The mean tumor position variation between consecutive BHs was 0.2 [standard deviation (SD) 1.7] mm in the inferior direction and 0.5 (SD 0.8) mm in the anterior direction. Conclusion: We observed substantial pancreatic tumor motion during BH as well as considerable position variation between consecutive BHs on a single day. We recommend further quantifying these uncertainties before introducing breath-hold during radiation treatment of pancreatic cancer patients. Also, the diaphragm cannot be used as a surrogate for pancreatic tumor motion.

Abdominal organ motion during inhalation and exhalation breath-holds: pancreatic motion at different lung volumes compared

“…Earlier, we performed a patient study in which we determined the tumor motion during 30-second inhalation breath-holds with a lung volume of ~75% of the inspiratory capacity (lung volumes were determined using a spirometer) [13,14]. When comparing our current data to the patient data from that study, we see that the observed tumor motion magnitude in the IS direction during 30-second inhalation breath-holds in patients (mean: 4.7 mm; SD: 3.0 mm) was similar to the motion of the pancreatic head in the IS direction during the first 30 s of BH 70% in this study (mean: 4.8 mm; SD: 2.3 mm).…”

“…The position variation of the tumor between multiple consecutive breath-holds, both inhalation and exhalation, has already been thoroughly determined for abdominal tumors [6,7,9,10,13,14]; mean variations of 1.2 and 2.3 mm were reported in the inferior-superior (IS) direction for inhalation and exhalation breath-holds, respectively [6,7]. The interfractional tumor position variation is similar for inhalation and exhalation breath-holds [15].…”

“…Also, exhalation breath-holds are more challenging to perform and therefore often result in shorter breath-hold durations than inhalation breath-holds [6,9,16]. The generally good organ stability during exhalation breath-holds is 4 in great contrast with the large organ drifts that have been observed during inhalation breath-holds in healthy subjects and patients [13,14,17,18]. In addition, it was observed that the motion during inhalation breath-holds was more pronounced at the beginning of the breath-hold [17,18].…”

An evaluation of motion mitigation techniques for pancreatic SBRT

“…The primary drawback to respiratory gating is the lengthening of treatment times, although these can be accounted for by using high dose-rate, flattening-filter free beams. Another common technique requires that the patient hold their breath during treatment; however, this has been shown to have poor accuracy for pancreatic tumors [12]. Other methods attempt to track the tumor directly without the use of an external surrogate [13,14].…”

Positional repeatability and variation in internal and external markers during volumetric-modulated arc therapy under end-exhalation breath-hold conditions for pancreatic cancer patients

“…Of these techniques, BH is one of the most commonly used owing to its versatility (2). Some researchers reported that BH was clinically useful in cases with disease sites such as the lung, breast, liver, and pancreas (6)(7)(8)(9)(10)(11). At our institution, VMAT has been used clinically under BH conditions at the end-exhalation (EE) phase for pancreatic cancer (9,12).…”