Purpose. To investigate whether magnesium oxide reduces the interfraction motion of the prostate and the amount of rectal filling and rectal gas, which influences prostate position during... Show morePurpose. To investigate whether magnesium oxide reduces the interfraction motion of the prostate and the amount of rectal filling and rectal gas, which influences prostate position during radiotherapy for prostate cancer.Patients and methods. From December 2008 to February 2010, 92 prostate cancer patients scheduled for intensity-modulated radiotherapy (77 Gy in 35 fractions) using fiducial marker-based position verification were randomly assigned to receive magnesium oxide (500 mg twice a day) or placebo during radiotherapy. In a previous study, we investigated the effect on intrafraction motion and did not find a difference between the treatment arms. Here, we compared the interfraction prostate motion between the two treatment arms as well as the amount of rectal filling and rectal air pockets using pretreatment planning computed tomography and magnetic resonance imagingscans.Results. There was no statistically significant difference between the treatment arms in translation and rotation of the prostate between treatment fractions, except for the rotation around the cranial caudal axis. However, the difference was less than 1 degrees and therefore considered not clinically relevant. There was no significant difference in the amount of rectal filling and rectal air pockets between the treatment arms.Conclusion. Magnesium oxide is not effective in reducing the interfraction prostate motion or the amount of rectal filling and rectal gas during external-beam radiotherapy. Therefore, magnesium oxide is not recommended in clinical practice for these purposes. Show less
Lips, I.M.; Kotte, A.N.T.J.; Gils, C.H. van; Leerdam, M.E. van; Heide, U.A. van der; Vulpen, M. van 2011
Purpose: To evaluate the effect of an antiflatulent dietary advice on the intrafraction prostate motion in patients treated with intensity-modulated radiotherapy (IMRT) for prostate cancer.Methods... Show morePurpose: To evaluate the effect of an antiflatulent dietary advice on the intrafraction prostate motion in patients treated with intensity-modulated radiotherapy (IMRT) for prostate cancer.Methods and Materials: Between February 2002 and December 2009, 977 patients received five-beam IMRT for prostate cancer to a dose of 76 Gy in 35 fractions combined with fiducial markers for position verification. In July 2008, the diet, consisting of dietary guidelines to obtain regular bowel movements and to reduce intestinal gas by avoiding certain foods and air swallowing, was introduced to reduce the prostate motion. The intrafraction prostate movement was determined from the portal images of the first segment of all five beams. Clinically relevant intrafraction motion was defined as >= 50% of the fractions with an intrafraction motion outside a range of 3 mm.Results: A total of 739 patients were treated without the diet and 105 patients were treated with radiotherapy after introduction of the diet. The median and interquartile range of the average intrafraction motion per patient was 2.53 mm (interquartile range, 2.2-3.0) without the diet and 3.00 mm (interquartile range, 2.4-3.5) with the diet (p < .0001). The percentage of patients with clinically relevant intrafraction motion increased statistically significant from 19.1% without diet to 42.9% with a diet (odds ratio, 3.18; 95% confidence interval, 2.07-4.88; p < .0001).Conclusions: The results of the present study suggest that antiflatulent dietary advice for patients undergoing IMRT for prostate cancer does not reduce the intrafraction movement of the prostate. Therefore, antiflatulent dietary advice is not recommended in clinical practice for this purpose. (C) 2011 Elsevier Inc. Show less
