Marker-based quantification of interfractional tumor position variation and the use of markers for setup verification in radiation therapy for esophageal cancer.

PURPOSE: The aim of this study was to quantify interfractional esophageal tumor position variation using markers and investigate the use of markers for setup verification. MATERIALS AND METHODS: Sixty-five markers placed in the tumor volumes of 24 esophageal cancer patients were identified in computed tomography (CT) and follow-up cone-beam CT. For each patient we calculated pairwise distances between markers over time to evaluate geometric tumor volume variation. We then quantified marker displacements relative to bony anatomy and estimated the variation of systematic (Σ) and random errors (σ). During bony anatomy-based setup verification, we visually inspected whether the markers were inside the planning target volume (PTV) and attempted marker-based registration. RESULTS: Minor time trends with substantial fluctuations in pairwise distances implied tissue deformation. Overall, Σ(σ) in the left-right/cranial-caudal/anterior-posterior direction was 2.9(2.4)/4.1(2.4)/2.2(1.8) mm; for the proximal stomach, it was 5.4(4.3)/4.9(3.2)/1.9(2.4) mm. After bony anatomy-based setup correction, all markers were inside the PTV. However, due to large tissue deformation, marker-based registration was not feasible. CONCLUSIONS: Generally, the interfractional position variation of esophageal tumors is more pronounced in the cranial-caudal direction and in the proximal stomach. Currently, marker-based setup verification is not feasible for clinical routine use, but markers can facilitate the setup verification by inspecting whether the PTV covers the tumor volume adequately.

Reduction of heart volume during neoadjuvant chemoradiation in patients with resectable esophageal cancer.

BACKGROUND AND PURPOSE: Neoadjuvant chemoradiation (nCRT) followed by surgery is considered curative intent treatment for patients with resectable esophageal cancer. The aim was to establish hemodynamic aspects of changes in heart volume and to explore whether changes in heart volume resulted in clinically relevant changes in the dose distribution of radiotherapy. METHODS: A prospective study was conducted in patients who were treated with nCRT consisting of carboplatin and paclitaxel concomitant with radiotherapy (41.4 Gy/1.8 Gy per fraction). Physical parameters, cardiac volume on CT and Cone beam CT, cardiac blood markers and cardiac ultrasound were obtained. RESULTS: In 23 patients a significant decrease of 55.3 ml in heart volume was detected (95% CI 36.7-73.8 ml, p<0.001). There was a decrease in both systolic (mean decrease 18 mmHg, 95% CI 11-26 mmHg, p<0.001) and diastolic blood pressure (mean decrease 8 mmHg, 95% CI 2-14 mmHg, p=0.008) and an increase in heart rate with 6 beats/min (95% CI 1-11 beats/min, p=0.021). Except for Troponin T, no change in other cardiac markers and echocardiography parameters were observed. The change in heart volume did not result in a clinically relevant change in radiation dose distribution. CONCLUSION: Heart volume was significantly reduced, but was not accompanied by overt cardiac dysfunction. All observed changes in hemodynamic parameters are consistent with volume depletion. Adaptation of the treatment plan during the course of radiotherapy is not advocated.

Reduction in cardiac volume during chemoradiotherapy for patients with esophageal cancer.

We investigated the change in cardiac volume over the course of chemoradiotherapy in 26 patients treated for esophageal cancer, using cone beam CT imaging. The cardiac volume reduced significantly, with a median reduction of 8%. A significant relationship with planned cardiac dose was not found.