@article{DietzschBraesigkSeideletal.2022,
  author    = {Dietzsch, Stefan and Braesigk, Annett and Seidel, Clemens and Remmele, Julia and Kitzing, Ralf and Schlender, Tina and Mynarek, Martin and Geismar, Dirk and Jablonska, Karolina and Schwarz, Rudolf and Pazos, Montserrat and Weber, Damien C. and Frick, Silke and Gurtner, Kristin and Matuschek, Christiane and Harrabi, Semi Ben and Gl{\"u}ck, Albrecht and Lewitzki, Victor and Dieckmann, Karin and Benesch, Martin and Gerber, Nicolas U. and Obrecht, Denise and Rutkowski, Stefan and Timmermann, Beate and Kortmann, Rolf-Dieter},
  title     = {Types of deviation and review criteria in pretreatment central quality control of tumor bed boost in medulloblastoma—an analysis of the German Radiotherapy Quality Control Panel in the SIOP PNET5 MB trial},
  series = {Strahlentherapie und Onkologie},
  volume    = {198},
  journal   = {Strahlentherapie und Onkologie},
  number    = {3},
  issn      = {0179-7158},
  doi       = {10.1007/s00066-021-01822-0},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-307812},
  pages     = {282-290},
  year      = {2022},
  abstract  = {Purpose In Germany, Austria, and Switzerland, pretreatment radiotherapy quality control (RT-QC) for tumor bed boost (TB) in non-metastatic medulloblastoma (MB) was not mandatory but was recommended for patients enrolled in the SIOP PNET5 MB trial between 2014 and 2018. This individual case review (ICR) analysis aimed to evaluate types of deviations in the initial plan proposals and develop uniform review criteria for TB boost. Patients and methods A total of 78 patients were registered in this trial, of whom a subgroup of 65 patients were available for evaluation of the TB treatment plans. Dose uniformity was evaluated according to the definitions of the protocol. Additional RT-QC criteria for standardized review of target contours were elaborated and data evaluated accordingly. Results Of 65 initial TB plan proposals, 27 (41.5\%) revealed deviations of target volume delineation. Deviations according to the dose uniformity criteria were present in 14 (21.5\%) TB plans. In 25 (38.5\%) cases a modification of the RT plan was recommended. Rejection of the TB plans was rather related to unacceptable target volume delineation than to insufficient dose uniformity. Conclusion In this analysis of pretreatment RT-QC, protocol deviations were present in a high proportion of initial TB plan proposals. These findings emphasize the importance of pretreatment RT-QC in clinical trials for MB. Based on these data, a proposal for RT-QC criteria for tumor bed boost in non-metastatic MB was developed.},
  language  = {en}
}
@article{GersztenSahgalSheehanetal.2013,
  author    = {Gerszten, Peter C. and Sahgal, Arjun and Sheehan, Jason P. and Kersh, Ronald and Chen, Stephanie and Flickinger, John C. and Quader, Mubina and Fahim, Daniel and Grills, Inga and Shin, John H. and Winey, Brian and Oh, Kevin and Sweeney, Reinhart A. and Guckenberger, Matthias},
  title     = {A multi-national report on methods for institutional credentialing for spine radiosurgery},
  series = {Radiation Oncology},
  volume    = {8},
  journal   = {Radiation Oncology},
  number    = {158},
  doi       = {10.1186/1748-717X-8-158},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-131485},
  year      = {2013},
  abstract  = {Background: Stereotactic body radiotherapy and radiosurgery are rapidly emerging treatment options for both malignant and benign spine tumors. Proper institutional credentialing by physicians and medical physicists as well as other personnel is important for the safe and effective adoption of spine radiosurgery. This article describes the methods for institutional credentialing for spine radiosurgery at seven highly experienced international institutions. Methods: All institutions (n = 7) are members of the Elekta Spine Radiosurgery Research Consortium and have a dedicated research and clinical focus on image-guided spine radiosurgery. A questionnaire consisting of 24 items covering various aspects of institutional credentialing for spine radiosurgery was completed by all seven institutions. Results: Close agreement was observed in most aspects of spine radiosurgery credentialing at each institution. A formal credentialing process was believed to be important for the implementation of a new spine radiosurgery program, for patient safety and clinical outcomes. One institution has a written policy specific for spine radiosurgery credentialing, but all have an undocumented credentialing system in place. All institutions rely upon an in-house proctoring system for the training of both physicians and medical physicists. Four institutions require physicians and medical physicists to attend corporate sponsored training. Two of these 4 institutions also require attendance at a non-corporate sponsored academic society radiosurgery course. Corporate as well as non-corporate sponsored training were believed to be complimentary and both important for training. In 5 centers, all cases must be reviewed at a multidisciplinary conference prior to radiosurgery treatment. At 3 centers, neurosurgeons are not required to be involved in all cases if there is no evidence for instability or spinal cord compression. Backup physicians and physicists are required at only 1 institution, but all institutions have more than one specialist trained to perform spine radiosurgery. All centers believed that credentialing should also be device specific, and all believed that professional societies should formulate guidelines for institutions on the requirements for spine radiosurgery credentialing. Finally, in 4 institutions radiation therapists were required to attend corporate-sponsored device specific training for credentialing, and in only 1 institution were radiation therapists required to also attend academic society training for credentialing. Conclusions: This study represents the first multi-national report of the current practice of institutional credentialing for spine radiosurgery. Key methodologies for safe implementation and credentialing of spine radiosurgery have been identified. There is strong agreement among experienced centers that credentialing is an important component of the safe and effective implementation of a spine radiosurgery program.},
  language  = {en}
}
@article{WackExnerWegeneretal.2020,
  author    = {Wack, Linda J. and Exner, Florian and Wegener, Sonja and Sauer, Otto A.},
  title     = {The impact of isocentric shifts on delivery accuracy during the irradiation of small cerebral targets — Quantification and possible corrections},
  series = {Journal of Applied Clinical Medical Physics},
  volume    = {21},
  journal   = {Journal of Applied Clinical Medical Physics},
  number    = {5},
  doi       = {10.1002/acm2.12854},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-218146},
  pages     = {56-64},
  year      = {2020},
  abstract  = {Purpose To assess the impact of isocenter shifts due to linac gantry and table rotation during cranial stereotactic radiosurgery on D\(_{98}\), target volume coverage (TVC), conformity (CI), and gradient index (GI). Methods Winston-Lutz (WL) checks were performed on two Elekta Synergy linacs. A stereotactic quality assurance (QA) plan was applied to the ArcCHECK phantom to assess the impact of isocenter shift corrections on Gamma pass rates. These corrections included gantry sag, distance of collimator and couch axes to the gantry axis, and distance between cone-beam computed tomography (CBCT) isocenter and treatment beam (MV) isocenter. We applied the shifts via script to the treatment plan in Pinnacle 16.2. In a planning study, isocenter and mechanical rotation axis shifts of 0.25 to 2 mm were applied to stereotactic plans of spherical planning target volumes (PTVs) of various volumes. The shifts determined via WL measurements were applied to 16 patient plans with PTV sizes between 0.22 and 10.4 cm3. Results ArcCHECK measurements of a stereotactic treatment showed significant increases in Gamma pass rate for all three measurements (up to 3.8 percentage points) after correction of measured isocenter deviations. For spherical targets of 1 cm3, CI was most severely affected by increasing the distance of the CBCT isocenter (1.22 to 1.62). Gradient index increased with an isocenter-collimator axis distance of 1.5 mm (3.84 vs 4.62). D98 (normalized to reference) dropped to 0.85 (CBCT), 0.92 (table axis), 0.95 (collimator axis), and 0.98 (gantry sag), with similar but smaller changes for larger targets. Applying measured shifts to patient plans lead to relevant drops in D\(_{98}\) and TVC (7\%) for targets below 2 cm\(^3\) treated on linac 1. Conclusion Mechanical deviations during gantry, collimator, and table rotation may adversely affect the treatment of small stereotactic lesions. Adjustments of beam isocenters in the treatment planning system (TPS) can be used to both quantify their impact and for prospective correction of treatment plans.},
  language  = {en}
}
@article{WegenerSchindhelmSauer2022,
  author    = {Wegener, Sonja and Schindhelm, Robert and Sauer, Otto A.},
  title     = {Implementing corrections of isocentric shifts for the stereotactic irradiation of cerebral targets: Clinical validation},
  series = {Journal of Applied Clinical Medical Physics},
  volume    = {23},
  journal   = {Journal of Applied Clinical Medical Physics},
  number    = {5},
  doi       = {10.1002/acm2.13577},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-312906},
  year      = {2022},
  abstract  = {Purpose: Any Linac will show geometric imprecisions, including non-ideal alignment of the gantry, collimator and couch axes, and gantry sag or wobble. Their angular dependence can be quantified and resulting changes of the dose distribution predicted (Wack, JACMP 20(5), 2020). We analyzed whether it is feasible to correct geometric shifts during treatment planning. The successful implementation of such a correction procedure was verified by measurements of different stereotactic treatment plans. Methods: Isocentric shifts were quantified for two Elekta Synergy Agility Linacs using the QualiForMed ISO-CBCT+ module, yielding the shift between kV and MV isocenters, the gantry flex and wobble as well as the positions of couch and collimator rotation axes. Next, the position of each field's isocenter in the Pinnacle treatment planning system was adjusted accordingly using a script. Fifteen stereotactic treatment plans of cerebral metastases (0.34 to 26.53 cm3) comprising 9-11 beams were investigated; 54 gantry and couch combinations in total. Unmodified plans and corrected plans were measured using the Sun Nuclear SRS-MapCHECK with the Stereophan phantom and evaluated using gamma analysis. Results: Geometric imprecisions, such as shifts of up to 0.8 mm between kV and MV isocenter, a couch rotation axis 0.9 mm off the kV isocente,r and gantry flex with an amplitude of 1.1 mm, were found. For eight, mostly small PTVs D98 values declined more than 5\% by simulating these shifts. The average gamma (2\%/2 mm, absolute, global, 20\% threshold) was reduced from 0.53 to 0.31 (0.32 to 0.30) for Linac 1 (Linac 2) when including the isocentric corrections. Thus, Linac 1 reached the accuracy level of Linac 2 after correction. Conclusion: Correcting for Linac geometric deviations during the planning process is feasible and was dosimetrically validated. The dosimetric impact of the geometric imperfections can vary between Linacs and should be assessed and corrected where necessary.},
  language  = {en}
}