Marie-Claude Biston1, Timothée Zaragori2, Laurent Delcoudert2, Marie Fargier-Voiron2, Alexandre Munoz2, Coralie Gorsse2, David Sarrut3, Pascal Pommier2. 1. Léon Bérard Cancer Center, University of Lyon, France; Université de Lyon, CREATIS, CNRS UMR5220, Inserm U1044, INSA, Lyon, France. Electronic address: marie-claude.biston@lyon.unicancer.fr. 2. Léon Bérard Cancer Center, University of Lyon, France. 3. Léon Bérard Cancer Center, University of Lyon, France; Université de Lyon, CREATIS, CNRS UMR5220, Inserm U1044, INSA, Lyon, France.
Abstract
BACKGROUND AND PURPOSE: To compare two in-beam monitoring devices for prostate radiotherapy: intra-prostatic electromagnetic transmitters (EM-T) (RayPilot®, Micropos Medical) and ultrasound imaging using transperineal probe (TP-US) (Clarity®, Elekta) used concomitantly on phantom and on patients. MATERIALS AND METHODS: The phantom study evaluated accuracy in presence of known translations and rotations. Then intra-fraction motions were analyzed for 10 prostate cancer patients implanted with the EM-T 8 days before the simulation CT (171 sessions). The percent time in which the differences between the systems were 1-5 mm were scored for each direction. RESULTS: Experiments on phantom confirmed no interference between the systems and showed deviations of less than 0.5 mm when translations were applied progressively. In presence of rotations (5-15°), both systems displayed systematic shifts up to 6.9 and 3.8 mm for the TP-US and the EM-T, respectively. Absolute mean differences between displacements observed on patients with EM-T and TP-US were ≤0.55 mm in all directions except for one patient (≤1.77 mm). With an exception for this patient, a strong correlation was found in left-right direction: differences >2 mm were monitored less than 0.22% of the time (mean acquisition time:164 minutes) and never exceeded 5 s. Maximum differences were observed in supero-inferior direction with differences >2 mm monitored more than 6.5% of the time for 3 patients. Large prostate rotations, the presence of gas and EM-T location in the prostate may explain important differences. CONCLUSION: Apart from the systematic shifts induced by the rotations, the two systems were correlated and represent feasible solutions for monitoring prostate cancer treatment.
BACKGROUND AND PURPOSE: To compare two in-beam monitoring devices for prostate radiotherapy: intra-prostatic electromagnetic transmitters (EM-T) (RayPilot®, Micropos Medical) and ultrasound imaging using transperineal probe (TP-US) (Clarity®, Elekta) used concomitantly on phantom and on patients. MATERIALS AND METHODS: The phantom study evaluated accuracy in presence of known translations and rotations. Then intra-fraction motions were analyzed for 10 prostate cancerpatients implanted with the EM-T 8 days before the simulation CT (171 sessions). The percent time in which the differences between the systems were 1-5 mm were scored for each direction. RESULTS: Experiments on phantom confirmed no interference between the systems and showed deviations of less than 0.5 mm when translations were applied progressively. In presence of rotations (5-15°), both systems displayed systematic shifts up to 6.9 and 3.8 mm for the TP-US and the EM-T, respectively. Absolute mean differences between displacements observed on patients with EM-T and TP-US were ≤0.55 mm in all directions except for one patient (≤1.77 mm). With an exception for this patient, a strong correlation was found in left-right direction: differences >2 mm were monitored less than 0.22% of the time (mean acquisition time:164 minutes) and never exceeded 5 s. Maximum differences were observed in supero-inferior direction with differences >2 mm monitored more than 6.5% of the time for 3 patients. Large prostate rotations, the presence of gas and EM-T location in the prostate may explain important differences. CONCLUSION: Apart from the systematic shifts induced by the rotations, the two systems were correlated and represent feasible solutions for monitoring prostate cancer treatment.
Authors: Alexander Grimwood; Hassan Rivaz; Hang Zhou; Helen A McNair; Klaudiusz Jakubowski; Jeffrey C Bamber; Alison C Tree; Emma J Harris Journal: Radiother Oncol Date: 2020-05-06 Impact factor: 6.280