Quality assurance standards drive improvements in the profile of radiation therapy departments participating in trials of the EORTC Radiation Oncology Group.

BACKGROUND AND PURPOSE: The Facility Questionnaire (FQ) of the European Organisation for Research and Treatment of Cancer Radiation Oncology Group (EORTC-ROG) evaluates the human, technical and organizational resources at each EORTC member institution. The purpose of this study is to use the FQ database to assess the improvement of radiation therapy (RT) structures and resources within the EORTC compared to the previous surveys performed by our group. MATERIAL AND METHODS: We report the content of the current FQ database, completed online by 156 EORTC candidate member institutions from 22 countries between February 2011 and February 2013. Results are compared to FQ-published data from 1992 and 2007. RESULTS: The average number of patients per year per EORTC institution is 2381 (range 350-12,000) an 18.2% increase compared to the 2007 figures. From 2007 to 2013 the average number of radiation oncologists, physicists and radiation technologists per EORTC institution has increased by 27% (from 8.5 to 10.8), 41% (from 5.2 to 7.4) and 38% (from 26.1 to 36.1) respectively. Consequently the number of patients per year per radiation oncologist has decreased from 258 to 243, for physicists from 426 to 354 and for radiation technologists from 107 to 86. One hundred and forty-six (94%) and 101 (65%) institutions can now deliver IMRT and SBRT, compared to 77 (79%) and 53 (54%) in 2007. CONCLUSIONS: The standards set by the EORTC-ROG are met by a continually improving number of institutions, helping to safeguard use of advanced technologies in EORTC-ROG clinical trials.

Software-controlled, highly automated intrafraction prostate motion correction with intrafraction stereographic targeting: System description and clinical results.

PURPOSE: A new system for software-controlled, highly automated correction of intrafraction prostate motion," intrafraction stereographic targeting" (iSGT), is described and evaluated. METHODS: At our institute, daily prostate positioning is routinely performed at the start of treatment beam using stereographic targeting (SGT). iSGT was implemented by extension of the SGT software to facilitate fast and accurate intrafraction motion corrections with minimal user interaction. iSGT entails megavoltage (MV) image acquisitions with the first segment of selected IMRT beams, automatic registration of implanted markers, followed by remote couch repositioning to correct for intrafraction motion above a predefined threshold, prior to delivery of the remaining segments. For a group of 120 patients, iSGT with corrections for two nearly lateral beams was evaluated in terms of workload and impact on effective intrafraction displacements in the sagittal plane. RESULTS: SDs of systematic (Σ) and random (σ) displacements relative to the planning CT measured directly after initial SGT setup correction were <0.5 and <0.8 mm, respectively. Without iSGT corrections, effective Σ and σ for the 11-min treatments would increase to Σ(eff) < 1.1 mm and σ(eff) < 1.2 mm. With the iSGT procedure with an action level of 4 mm, effective positioning errors were reduced to Σ(eff) < 0.8 mm and σ(eff) < 1.0 mm, with 23.1% of all fractions requiring a correction. Computer simulations demonstrated that with an action level of 2 mm, the errors would have been reduced to Σ(eff) < 0.6 mm and σ(eff) < 0.7 mm, requiring corrections in 82.4% of the fractions. Because iSGT is highly automated, the extra time added by iSGT is <30 s if a correction is required. CONCLUSIONS: Without increasing imaging dose, iSGT successfully reduces intrafraction prostate motion with minimal workload and increase in fraction time. An action level of 2 mm is recommended.

Application of the No Action Level (NAL) protocol to correct for prostate motion based on electronic portal imaging of implanted markers.

PURPOSE: To evaluate the efficacy of the No Action Level (NAL) off-line correction protocol in the reduction of systematic prostate displacements as determined from electronic portal images (EPI) using implanted markers. METHODS AND MATERIALS: Four platinum markers, two near the apex and two near the base of the prostate, were implanted for localization purposes in patients who received fractionated high dose rate brachytherapy. During the following course of 25 fractions of external beam radiotherapy, the position of each marker relative to the corresponding position in digitally reconstructed radiographs (DRRs) was measured in EPI in 15 patients for on average 17 fractions per patient. These marker positions yield the composite displacements due to both setup error and internal prostate motion, relative to the planning computed tomography scan. As the NAL protocol is highly effective in reducing systematic errors (recurring each fraction) due to setup inaccuracy alone, we investigated its efficacy in reducing systematic composite displacements. The analysis was performed for the center of mass (COM) of the four markers, as well as for the cranial and caudal markers separately. Furthermore, the impact of prostate rotation on the achieved positioning accuracy was determined. RESULTS: In case of no setup corrections, the standard deviations of the systematic composite displacements of the COM were 3-4 mm in the craniocaudal and anterior-posterior directions, and 2 mm in the left-right direction. The corresponding SDs of the random displacements (interfraction fluctuations) were 2-3 mm in each direction. When applying a NAL protocol based on three initial treatment fractions, the SDs of the systematic COM displacements were reduced to 1-2 mm. Displacements at the cranial end of the prostate were slightly larger than at the caudal end, and quantitative analysis showed this originates from left-right axis rotations about the prostate apex. Further analysis revealed that significant time trends are present in these prostate rotations. No significant trends were observed for the prostate translations. CONCLUSIONS: The NAL protocol based on marker positions in EPI halved the composite systematic displacements using only three imaged fractions per patient, and thus allowed for a significant reduction of planning margins. Although large rotations of the prostate, and time trends therein, were observed, the net impact on the measured displacements and on the accuracy obtained with NAL was small.