ABSTRACT
PURPOSE: To evaluate the effectiveness of abdominal compression (AC) as a respiratory motion management method for the heart and stomach during stereotactic arrhythmia radioablation (STAR). METHODS: 4D computed tomography (4DCT) scans of patients imaged with AC or without AC (free-breathing: FB) were obtained from ventricular-tachycardia (VT) (n = 3), lung cancer (n = 18), and liver cancer (n = 18) patients. Patients treated for VT were imaged both FB and with AC. Lung and liver patients were imaged once with FB or with AC, respectively. The heart, left ventricle (LV), LV components (LVCs), and stomach were contoured on each phase of the 4DCTs. Centre of mass (COM) translations in the left/right (LR), ant/post (AP), and sup/inf (SI) directions were measured for each structure. Minimum distances between LVCs and the stomach over the respiratory cycle were also measured on each 4DCT phase. Mann-Whitney U-tests were performed between AC and FB datasets with a significance of α = 0.05. RESULTS: No statistical difference (all p values were >0.05) was found in COM translations between FB and AC patient datasets for all contoured cardiac structures. A reduction in COM translation with AC relative to FB was patient, direction, and structure specific for the three VT patients. A significant decrease in the AP range of motion of the stomach was observed under AC compared to FB. No statistical difference was found between minimum distances to the stomach and LVCs between FB and AC. CONCLUSIONS: AC was not a consistent motion management method for STAR, nor does not uniformly affect the separation distance between LVCs and the stomach. If AC is employed in future STAR protocols, the motion of the target volume and its relative distance to the stomach should be compared on two 4DCTs: one while the patient is FB and one under AC.
ABSTRACT
BACKGROUND AND PURPOSE: The rising cost of health care is of universal concern. If the cost effectiveness of conventional and novel radiotherapeutic strategies is to be established we need to have confidence in our estimates of both cost and effectiveness. The purpose of this study is to explore the degree of consistency of recently published cost estimates for radiation therapy. METHODS AND MATERIALS: Eleven publications form the basis of this analysis. From each study we have estimated the cost of a 21 fraction course (when possible) of radiation therapy. The costs have been decomposed into the three inputs: process, clinical infrastructure and supporting infrastructure. We have also investigated the time course of radiation therapy costs over the last two decades. RESULTS: From the latest four studies we conclude that the cost of a 21 fraction course of radiation therapy is 3239 euro+/-566 euro. The percentages of this total spent on process, clinical infrastructure and supporting infrastructure over the last 15 years are 54, 29 and 17, respectively. The real increase in the cost of radiotherapy over the last 15 years is estimated to be approximately 5.5%. CONCLUSION: Cost estimates for radiation therapy appear to be converging. However, we will need far more sophisticated analyses in the future if we are to establish the cost effectiveness of the newer treatment strategies currently under active clinical investigation.
