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Objective:To establish a novel clinical application process of the optical surface monitoring system (OSMS) in the cranial frameless stereotactic radiosurgery (SRS) and stereotactic radiotherapy (SRT), and to assess the accuracy and effectiveness of the OSMS in the intra-fraction motion monitoring of both cranial phantoms and cranial SRT patients fixed using the Q-Fix encompass immobilization system.Methods:The deviations of OSMS in the real-time motion monitoring were assessed by determining the deviations between the displacement of the cranial SRS phantoms detected by the OSMS and the predefined displacement of the Varian Edge six degrees of freedom (6DoF) couch. The ability of the OSMS to conduct real-time monitoring of the head movement was also analyzed when one camera was blocked by the rotary gantry of the accelerator and when the couch was at non-zero angles. Moreover, ten patients who received 50 fractions of cranial frameless SRT were enrolled in this study. All the patients were fixed using the Q-Fix Encompass system, and their intra-fraction motion was monitored using the OSMS. The intra-fraction errors of OSMS real-time monitoring throughout the treatment were obtained from the OSMS logs. The patients received cone-beam computed tomography (CBCT) after the beam delivery, and the six-dimensional errors were obtained as intra-fraction motion errors of the CBCT.Results:For the cranial phantoms, there was a close correlation between the OSMS monitoring deviations and the predefined displacement in six dimensions. The OSMS-detected 3D vector deviations in the translational and rotational directions were (0.28±0.10) mm and (0.15±0.09)°, respectively when the angel both the gantry and couch was 0° and were (0.35±0.13) mm and(0.17±0.09)°, respectively, when one camera was blocked. The OSMS monitoring deviations with the couch at a non-zero degree were greater than those at zero degree. The maximum deviations occurred when the couch was at 270° and were (0.69±0.19) mm and (0.32±0.12)°, respectively, in the translational and rotational directions. For the cranial SRT patients fixed using the Q-Fix Encompass system, the OSMS and CBCT showed comparable intra-fractional motion deviations, which were (0.40±0.26) and (0.29±0.10) mm, respectively in the translational direction and were (0.33±0.20)°and (0.26±0.08)° in the rotational direction.Conclusions:The OSMS is an effective tool for optically guided radiotherapy, which allows for intra-fraction real-time motion monitoring with sub-millimeter accuracy. Therefore, to ensure the accurate preformation of cranial SRS/SRT, it is necessary to conduct the intra-fractional position monitoring using OSMS.
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Objective: To evaluate intra-fractional prostate motion by applying four-dimensional real-time transperineal ultrasound (TPUS) so as to provide reference evidence for the moderate hypofrectionation radiotherapy for prostate cancer. Methods: Ten patients with prostate cancer were randomly selected to be treated with volume modulated radiotherapy (VMAT). TPUS was utilized to collect 60 intra-fraction data. Prior to each treatment for all the patients, CBCT was adopted to correct inter-fraction setup errors. During treatment, four-dimensional real-time ultrasound images were acquired to monitor the 3D prostate motion. Results: Among all the data, the maximum distance of prostate motion was 1.85 mm in the left direction, 0.50 mm in the right direction, 1.83 mm in the anterior direction, 3.04 mm in the posterior direction, 2.68 mm in the cranial direction, and 1.75 mm in the caudal direction. The percentage of fractions in which the distance of prostate motion was more than 2 mm among all treatment fractions was 3% in the left and right (LR) direction, 11% in the anterior and posterior (AP) direction, and 5% in the cranial and caudal (CC) direction. The distance was greater in AP direction than in AP direction and CC direction. Results: TUPS is a non-invasive and reliable technique which can detect the real-time motion of the prostate during radiotherapy aiming to prevent tumor target areas from being missed or normal tissues from being overexposed.
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Objective To apply real-time transperineal ultrasound ( TPUS) to monitor the intra-fractional prostate motion,collect and analyze the data of the prostate motion,aiming to provide evidence for the optimization of the target area and plan of radiotherapy for prostate cancer. Methods TPUS is a non-invasive monitoring technique that utilizes an automatic scanning ultrasound probe to dynamically monitor and correct the motion of organs during radiotherapy. In this study, TPUS was utilized to collect 1588 intra-fractional data of 70 patients with prostate cancer. Prior to each cycle of radiotherapy,CBCT was adopted to correct the errors between intra-factional data by using VMAT. During radiotherapy, real-time ( once per second) ultrasound images were acquired to monitor the 3D motion of the prostate on the x (left+,right-),y (cranial+, caudal-), and z ( abdominal+, dorsal-) axes, emphasizing the analysis of 4D motion of the prostate. Results All patients successfully completed the treatment and data collection. The median time of effective monitoring per faction was 179 seconds (132-286 seconds). During 95% of the monitoring time,the distance of prostate motion was 2. 22 mm in the left direction,2. 17 mm in the right,2. 08 mm in the cranial, 1. 98 mm in the caudal,2. 44 mm in the abdominal and 2. 97 mm in the dorsal direction,respectively. In the x,y and z axes,the percentage of time in which the distance of prostate motion less than 1 mm among the total time was 83. 07%,85. 46% and 78. 27%,respectively,whereas 97. 70%,97. 87% and 96. 45% for＜3 mm, respectively. Conclusions TPUS is a non-invasive real-time monitoring technique,which can detect the 4D motion of the prostate during radiotherapy. By using VMAT,the range of prostate motion is relatively small, and the motion range is less than 3 mm in each direction within 95% of the time.