@article{RichterExnerBratengeieretal.2019,
  author    = {Richter, Anne and Exner, Florian and Bratengeier, Klaus and Polat, B{\"u}lent and Flentje, Michael and Weick, Stefan},
  title     = {Impact of beam configuration on VMAT plan quality for Pinnacle\(^3\)Auto-Planning for head and neck cases},
  series = {Radiation Oncology},
  volume    = {14},
  journal   = {Radiation Oncology},
  doi       = {10.1186/s13014-019-1211-6},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-200301},
  pages     = {12},
  year      = {2019},
  abstract  = {Background The purpose of this study was to compare automatically generated VMAT plans to find the superior beam configurations for Pinnacle3 Auto-Planning and share "best practices". Methods VMAT plans for 20 patients with head and neck cancer were generated using Pinnacle3 Auto-Planning Module (Pinnacle3 Version 9.10) with different beam setup parameters. VMAT plans for single (V1) or double arc (V2) and partial or full gantry rotation were optimized. Beam configurations with different collimator positions were defined. Target coverage and sparing of organs at risk were evaluated based on scoring of an evaluation parameter set. Furthermore, dosimetric evaluation was performed based on the composite objective value (COV) and a new cross comparison method was applied using the COVs. Results The evaluation showed a superior plan quality for double arcs compared to one single arc or two single arcs for all cases. Plan quality was superior if a full gantry rotation was allowed during optimization for unilateral target volumes. A double arc technique with collimator setting of 15° was superior to a double arc with collimator 60° and a two single arcs with collimator setting of 15° and 345°. Conclusion The evaluation showed that double and full arcs are superior to single and partial arcs in terms of organs at risk sparing even for unilateral target volumes. The collimator position was found as an additional setup parameter, which can further improve the target coverage and sparing of organs at risk.},
  language  = {en}
}
@article{BratengeierHolubyevWegener2019,
  author    = {Bratengeier, Klaus and Holubyev, Kostyantyn and Wegener, Sonja},
  title     = {Steeper dose gradients resulting from reduced source to target distance—a planning system independent study},
  series = {Journal of Applied Clinical Medical Physics},
  volume    = {20},
  journal   = {Journal of Applied Clinical Medical Physics},
  number    = {1},
  doi       = {10.1002/acm2.12490},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-177424},
  pages     = {89-100},
  year      = {2019},
  abstract  = {Purpose: To quantify the contribution of penumbra in the improvement of healthy tissue sparing at reduced source-to-axis distance (SAD) for simple spherical target and different prescription isodoses (PI). Method: A TPS-independent method was used to estimate three-dimensional (3D) dose distribution for stereotactic treatment of spherical targets of 0.5 cm radius based on single beam two-dimensional (2D) film dosimetry measurements. 1 cm target constitutes the worst case for the conformation with standard Multi-Leaf Collimator (MLC) with 0.5 cm leaf width. The measured 2D transverse dose cross-sections and the profiles in leaf and jaw directions were used to calculate radial dose distribution from isotropic beam arrangement, for both quadratic and circular beam openings, respectively. The results were compared for standard (100 cm) and reduced SAD 70 and 55 cm for different PI. Results: For practical reduction of SAD using quadratic openings, the improvement of healthy tissue sparing (HTS) at distances up to 3 times the PTV radius was at least 6\%-12\%; gradient indices (GI) were reduced by 3-39\% for PI between 40\% and 90\%. Except for PI of 80\% and 90\%, quadratic apertures at SAD 70 cm improved the HTS by up to 20\% compared to circular openings at 100 cm or were at least equivalent; GI were 3\%-33\% lower for reduced SAD in the PI range 40\%-70\%. For PI = 80\% and 90\% the results depend on the circular collimator model. Conclusion: Stereotactic treatments of spherical targets delivered at reduced SAD of 70 or 55 cm using MLC spare healthy tissue around the target at least as good as treatments at SAD 100 cm using circular collimators. The steeper beam penumbra at reduced SAD seems to be as important as perfect target conformity. The authors argue therefore that the beam penumbra width should be addressed in the stereotactic studies.},
  language  = {en}
}
@phdthesis{Haeckel2017,
  author    = {H{\"a}ckel, Annalena},
  title     = {Implementierung und Umsetzbarkeit eines Tablet-gest{\"u}tzten Screenings auf Unterst{\"u}tzungsbedarf in der Radioonkologie},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-154974},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2017},
  abstract  = {Die Inzidenz und Pr{\"a}valenz von Krebserkrankungen pr{\"a}sentiert sich in den vergangenen Jahren ungebrochen hoch. Durch die stetige Optimierung der Versorgung werden Betroffenen neuartige Optionen offeriert. Moderne Onkotherapie zeichnet sich durch sektoren{\"u}bergreifende Kooperation aus. Diese komplexen Versorgungskonzepte k{\"o}nnen durch innovative Technologien simplifiziert werden. Vorliegende Arbeit er{\"o}rtert die Frage nach der Umsetzbarkeit Tablet-gest{\"u}tzter Screenings in der Routine der Strahlenmedizin. Die Erfassung der ESAS-Items und des Unterst{\"u}tzungsbedarfs erm{\"o}glichte nach dem Vorbild kanadischer Versorgungskonzepte definierte Aussagen zur Qualit{\"a}t der medizinischen Versorgung. Im Rahmen der Studie erhielten Tumorpatienten vor der perkutanen Radiotherapie (T1) ein Tablet-gest{\"u}tztes Symptom-Screening. Das Tablet-Screening wurde von den Teilnehmern bez{\"u}glich Bedienung und Nutzerfreundlichkeit evaluiert. Nach Abschluss der Radiotherapie erfolgte eine telefonische Nachbefragung der Teilnehmer (T2). Insgesamt partizipierten 332 Krebspatienten am Tablet-Screening. 79 potentielle Studienprobanden nahmen nicht teil. Als Hauptursachen zeigten sich fehlende Zeit (21,5\%), die Teilnahme an sonstigen Studien (20,3\%) und zu hohe psychische Belastungen (17,7\%). Der Anteil der Screening-Teilnehmer mit fundierten Vorkenntnissen im Umgang mit Tablet-PCs (15,7\%) war gering. Probanden mit Tablet-Vorerfahrungen waren signifikant j{\"u}nger als Unerfahrene. Anwendung und Nutzerfreundlichkeit erlangte hohe Zustimmung. Die wenigen (21,7\%) Bef{\"u}rworter konventioneller Stift-Papier-Frageb{\"o}gen waren signifikant {\"a}lter. 219 Screening-Teilnehmer stellten ihre ausgewerteten Symptom-Frageb{\"o}gen weiteren Auswertungen zur Verf{\"u}gung. Der Performance-Status wurde von Patient und Mediziner eher divergent bewertet (ĸ=0,254). Von T1 zu T2 nahm der Anteil positiv gescreenter Probanden ab. Kurativpatienten markierten bei den ESAS-Items M{\"u}digkeit, Kurzatmigkeit und Sonstiges signifikante Symptomverbesserungen. Bei Palliativpatienten zeigte Kurzatmigkeit signifikante Verbesserung, Depressionen hingegen signifikante Verschlechterung. Der schw{\"a}chste Unterst{\"u}tzungsbedarf (23,3\%) wurde beim ,,Bedarf an Informationen beim Erstellen von Patientenverf{\"u}gungen'' registriert. Die BUKA-Studie konnte die Chancen Tablet-gest{\"u}tzter Befragungen in der Routine der Radioonkologie darstellen. Das Screening markierte durchg{\"a}ngig positive Bewertungen sowie große Akzeptanz. Die positiven Ergebnisse deckten sich mit denen anderer Studien bez{\"u}glich EDV-gest{\"u}tzter Datenerhebung. Die oftmals nicht ausreichendende Zeit zur Studienteilnahme war jedoch nicht auf eine zu zeitintensive Bedienung von Tablet-PCs zur{\"u}ckzuf{\"u}hren. Die Anzahl der Screening-Items sollte der kurzen Wartezeit der Strahlenambulanz angepasst werden. EDV-Screenings sollten dar{\"u}ber hinaus zuk{\"u}nftig bereits von zuhause absolviert werden. Die zunehmende Technisierung des Alltags l{\"a}sst den Anteil PC-erfahrener Patienten weiter ansteigen. Die Einf{\"u}hrung EDV-gest{\"u}tzter Versionen bietet eine effektive M{\"o}glichkeit des Patienten-Monitoring als Grundlage multidisziplin{\"a}rer onkologischer Versorgung. Infolge der zunehmenden PC-gest{\"u}tzten Verarbeitung hochsensibler Patientendaten ist die Gew{\"a}hrleistung vollkommener Datensicherheit dringend notwendig. Im Gegensatz zu anderen Arbeiten pr{\"a}sentierte das Studienkollektiv {\"u}berwiegend Kurativpatienten mit gutem Allgemeinzustand. Trotz geringerer Symptombelastung konnten auch hier die positiven Effekte der Radiotherapie dargestellt werden. Der hohe Unterst{\"u}tzungsbedarf erschien oftmals dem mangelnden medizinischen Verst{\"a}ndnis der Betroffenen geschuldet. Kurativpatienten {\"a}ußerten deutlich mehr Interesse aktiv an der Therapie teilzuhaben. Palliativpatienten erschienen durch das {\"U}bermaß an Therapien entkr{\"a}ftet.},
  subject      = {Screening},
  language  = {de}
}
@phdthesis{Maier2023,
  author    = {Maier, Marco},
  title     = {Therapiezieleinsch{\"a}tzung von palliativ bestrahlten Patienten bei Erstvorstellung in der Radioonkologie},
  doi       = {10.25972/OPUS-32111},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-321119},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2023},
  abstract  = {In der vorliegenden Arbeit wurden die H{\"a}ufigkeit und m{\"o}gliche Pr{\"a}diktoren f{\"u}r eine {\"u}beroptimistische Therapiezieleinsch{\"a}tzung von palliativ bestrahlten onkologischen Patienten der Klinik und Poliklinik f{\"u}r Strahlentherapie des Universit{\"a}tsklinikum W{\"u}rzburg untersucht. Dazu wurden die Frage zur Therapiezieleinsch{\"a}tzung, die Integrated Palliative Care Outcome Scale (IPOS), das Distress-Thermometer und das Fatigue-Screening aus dem Patientenselbsteinsch{\"a}tzungsbogen, den die Patienten routinem{\"a}ßig vor dem {\"a}rztlichen Erstgespr{\"a}ch erhalten, sowie soziodemographische und krankheitsbezogene Daten aus der elektronischen Patientenakte analysiert (Untersuchungszeitraum 05/2018-05/2019). Die Einsch{\"a}tzung des Therapieziels galt als {\"u}beroptimistisch, wenn ein Patient f{\"a}lschlicherweise von dem Behandlungsziel „Heilung" ausging. Von einer realistischen Therapiezieleinsch{\"a}tzung wurde ausgegangen, wenn ein Patient von der Nichtheilbarkeit seiner Krebserkrankung ausging. Insgesamt wurden Daten von 283 Patienten ausgewertet, davon 133 Frauen (47\%) und 150 M{\"a}nner (53\%). Das mittlere Alter lag bei 66,7 Jahren (Spannweite 30-95 Jahre). Die drei h{\"a}ufigsten Tumorentit{\"a}ten waren Lungen- (26,9\%), Brust- (18,0\%) und Prostatakrebs (10,2\%). 64,7\% (183/283) der Patienten dieser Studie sch{\"a}tzten ihr Therapieziel {\"u}beroptimistisch ein. Es fanden sich statistisch signifikante Zusammenh{\"a}nge (p<0,05) mit einzelnen IPOS-Items, der bisherigen Dauer der Therapie unter palliativer Intention und dem Karnofsky-Index . Die beiden Variablen „Dauer der Therapie unter palliativer Intention" und „Karnofsky-Index" wurden in einer bin{\"a}r logistischen Regression als Pr{\"a}diktoren f{\"u}r eine {\"u}beroptimistische Therapiezieleinsch{\"a}tzung identifiziert. Da die Selbsteinsch{\"a}tzung vor der Erstbegegnung mit dem Strahlentherapeuten erfolgte, bleibt offen, inwieweit die Patienten- und Arzteinsch{\"a}tzung nach dem Aufkl{\"a}rungsgespr{\"a}ch h{\"a}ufiger {\"u}bereinstimmen als in der vorliegenden Studie (35,3\% realistische Therapiezieleinsch{\"a}tzung).},
  subject      = {Palliativmedizin},
  language  = {de}
}
@article{ZetzlRennerPittigetal.2021,
  author    = {Zetzl, Teresa and Renner, Agnes and Pittig, Andre and Jentschke, Elisabeth and Roch, Carmen and van Oorschot, Birgitt},
  title     = {Yoga effectively reduces fatigue and symptoms of depression in patients with different types of cancer},
  series = {Supportive Care in Cancer},
  volume    = {29},
  journal   = {Supportive Care in Cancer},
  issn      = {0941-4355},
  doi       = {10.1007/s00520-020-05794-2},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-235415},
  pages     = {2973-2982},
  year      = {2021},
  abstract  = {Purpose Examine the effects of an 8-week yoga therapy on fatigue in patients with different types of cancer. Methods A total of 173 cancer patients suffering from mild to severe fatigue were randomly allocated to yoga intervention (n = 84) (IG) versus waitlist control group (CG) (n = 88). Yoga therapy consisted of eight weekly sessions with 60 min each. The primary outcome was self-reported fatigue symptoms. Secondary outcomes were symptoms of depression and quality of life (QoL). Data were assessed using questionnaires before (T0) and after yoga therapy for IG versus waiting period for CG (T1). Results A stronger reduction of general fatigue (P = .033), physical fatigue (P = .048), and depression (P < .001) as well as a stronger increase in QoL (P = .002) was found for patients who attended 7 or 8 sessions compared with controls. Within the yoga group, both higher attendance rate and lower T0-fatigue were significant predictors of lower T1-fatigue (P ≤ .001). Exploratory results revealed that women with breast cancer report a higher reduction of fatigue than women with other types of cancer (P = .016) after yoga therapy. Conclusion The findings support the assumption that yoga therapy is useful to reduce cancer-related fatigue, especially for the physical aspects of fatigue. Women with breast cancer seem to benefit most, and higher attendance rate results in greater reduction of fatigue. Trial registration German Clinical Trials Register DRKS00016034},
  language  = {en}
}
@article{RadeloffRamosTiradoHaddadetal.2021,
  author    = {Radeloff, Katrin and Ramos Tirado, Mario and Haddad, Daniel and Breuer, Kathrin and M{\"u}ller, Jana and Hochmuth, Sabine and Hackenberg, Stephan and Scherzad, Agmal and Kleinsasser, Norbert and Radeloff, Andreas},
  title     = {Superparamagnetic iron oxide particles (VSOPs) show genotoxic effects but no functional impact on human adipose tissue-derived stromal cells (ASCs)},
  series = {Materials},
  volume    = {14},
  journal   = {Materials},
  number    = {2},
  issn      = {1996-1944},
  doi       = {10.3390/ma14020263},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-222970},
  year      = {2021},
  abstract  = {Adipose tissue-derived stromal cells (ASCs) represent a capable source for cell-based therapeutic approaches. For monitoring a cell-based application in vivo, magnetic resonance imaging (MRI) of cells labeled with iron oxide particles is a common method. It is the aim of the present study to analyze potential DNA damage, cytotoxicity and impairment of functional properties of human (h)ASCs after labeling with citrate-coated very small superparamagnetic iron oxide particles (VSOPs). Cytotoxic as well as genotoxic effects of the labeling procedure were measured in labeled and unlabeled hASCs using the MTT assay, comet assay and chromosomal aberration test. Trilineage differentiation was performed to evaluate an impairment of the differentiation potential due to the particles. Proliferation as well as migration capability were analyzed after the labeling procedure. Furthermore, the labeling of the hASCs was confirmed by Prussian blue staining, transmission electron microscopy (TEM) and high-resolution MRI. Below the concentration of 0.6 mM, which was used for the procedure, no evidence of genotoxic effects was found. At 0.6 mM, 1 mM as well as 1.5 mM, an increase in the number of chromosomal aberrations was determined. Cytotoxic effects were not observed at any concentration. Proliferation, migration capability and differentiation potential were also not affected by the procedure. Labeling with VSOPs is a useful labeling method for hASCs that does not affect their proliferation, migration and differentiation potential. Despite the absence of cytotoxicity, however, indications of genotoxic effects have been demonstrated.},
  language  = {en}
}
@article{ZetzlPittigRenneretal.2021,
  author    = {Zetzl, Teresa and Pittig, Andre and Renner, Agnes and van Oorschott, Birgitt and Jentschke, Elisabeth},
  title     = {Yoga therapy to reduce fatigue in cancer: effects of reminder e-mails and long-term efficacy},
  series = {Supportive Care in Cancer},
  volume    = {29},
  journal   = {Supportive Care in Cancer},
  number    = {12},
  issn      = {1433-7339},
  doi       = {10.1007/s00520-021-06345-z},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-268415},
  pages     = {7725-7735},
  year      = {2021},
  abstract  = {Objective To examine the efficacy of reminder e-mails to continue yoga therapy on practice frequency and fatigue in cancer patients and long-term effects of yoga on fatigue, depression, and quality of life. Methology One hundred two cancer patients who completed an 8-week yoga therapy were randomly allocated to two groups: reminder (N = 51) vs. no-reminder group (N = 51). After completing yoga therapy, the reminder group received weekly e-mails for 24 weeks, which reminded them of practicing yoga, whereas the no-reminder group did not. Primary outcomes were fatigue and practice frequency, and long-term outcomes were fatigue, depression, and quality of life. Data were assessed using questionnaires after yoga therapy (T1) and 6 months after completing yoga therapy (T2). Result A significantly stronger reduction of general (p = 0.038, d = 0.42) and emotional fatigue (p = 0.004, d = 0.59) and a higher increase of practice frequency (p = 0.015, d = 0.52) between T1 and T2 were found for the reminder group compared to the no-reminder group. In the mediation model, practice frequency as a mediator partially explained the changes in emotional fatigue (indirect effect B =  - 0.10). Long-term effects of yoga therapy regarding fatigue, depression, and quality of life were found (F > 7.46, p < 0.001, d > 0.54). Conclusion Weekly reminder e-mails after yoga therapy can positively affect general and emotional fatigue and help cancer patients with fatigue establish a regular yoga practice at home. However, higher practice frequency did not lead to higher physical or cognitive fatigue improvement, suggesting other factors that mediate efficacy on physical or cognitive fatigue, such as mindfulness or side effects of therapy.},
  language  = {en}
}
@article{TamihardjaRazinskasExneretal.2021,
  author    = {Tamihardja, J{\"o}rg and Razinskas, Gary and Exner, Florian and Richter, Anne and Kessler, Patrick and Weick, Stefan and Kraft, Johannes and Mantel, Frederick and Flentje, Michael and Polat, B{\"u}lent},
  title     = {Comparison of treatment plans for hypofractionated high-dose prostate cancer radiotherapy using the Varian Halcyon and the Elekta Synergy platforms},
  series = {Journal of Applied Clinical Medical Physics},
  volume    = {22},
  journal   = {Journal of Applied Clinical Medical Physics},
  number    = {9},
  doi       = {10.1002/acm2.13380},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-260722},
  pages     = {262-270},
  year      = {2021},
  abstract  = {Purpose To compare radiotherapy plans between an O-ring and a conventional C-arm linac for hypofractionated high-dose prostate radiotherapy in terms of plan quality, dose distribution, and quality assurance in a multi-vendor environment. Methods Twenty prostate cancer treatment plans were irradiated on the O-ring Varian Halcyon linac and were re-optimized for the C-arm Elekta Synergy Agility linac. Dose-volume histogram metrics for target coverage and organ at risk dose, quality assurance, and monitor units were retrospectively compared. Patient-specific quality assurance with ion chamber measurements, gamma index analysis, and portal dosimetry was performed using the Varian Portal Dosimetry system and the ArcCHECK® phantom (Sun Nuclear Corporation). Prostate-only radiotherapy was delivered with simultaneous integrated boost (SIB) volumetric modulated arc therapy (VMAT) in 20 fractions of 2.5/3.0 Gy each. Results For both linacs, target coverage was excellent and plan quality comparable. Homogeneity in PTVBoost was high for Synergy as well as Halcyon with a mean homogeneity index of 0.07 ± 0.01 and 0.05 ± 0.01, respectively. Mean dose for the organs at risk rectum and bladder differed not significantly between the linacs but were higher for the femoral heads and penile bulb for Halcyon. Quality assurance showed no significant differences in terms of ArcCHECK gamma pass rates. Median pass rate for 3\%/2 mm was 99.3\% (96.7 to 99.8\%) for Synergy and 99.8\% (95.6 to 100\%) for Halcyon. Agreement between calculated and measured dose was high with a median deviation of -0.6\% (-1.7 to 0.8\%) for Synergy and 0.2\% (-0.6 to 2.3\%) for Halcyon. Monitor units were higher for the Halcyon by approximately 20\% (p < 0.001). Conclusion Hypofractionated high-dose prostate cancer SIB VMAT on the Halcyon system is feasible with comparable plan quality in reference to a standard C-arm Elekta Synergy linac.},
  language  = {en}
}
@phdthesis{Cirak2019,
  author    = {Cirak, Marianne},
  title     = {Sedierung am Lebensende auf der Palliativstation},
  doi       = {10.25972/OPUS-17965},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-179651},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2019},
  abstract  = {Retrospektive Analyse von 181 Patienten, die im Zeitraum vom 01.02.2015 bis zum 31.03.2016 auf der Palliativstation des Universit{\"a}tsklinikums W{\"u}rzburg verstorben sind. Es wurde die palliative Sedierungstherapie untersucht unter folgenden Gesichtspunkten: Erfolgte sie leitliniengerecht (waren die Symptome therapierefrakt{\"a}r bzw. wurde eine proportionale Sedierung durchgef{\"u}hrt)? Wie l{\"a}sst sich die palliative Sedierungstherapie von aktiver Sterbehilfe abgrenzen? Welchen Einfluss hat das Delir? Welche Qualit{\"a}t hatte die Dokumentation? Die Autorin kommt zu dem Schluss, dass die palliative Sedierungstherapie ein wichtiges Instrument ist zur Symptomlinderung am Lebensende. Es ist auch eine sichere Therapiemaßnahme, solange sie leitliniengerecht durchgef{\"u}hrt wird. Die palliative Sedierungstherapie auf der Palliativstation der Universit{\"a}tsklinik W{\"u}rzburg konnte als leitliniengerecht best{\"a}tigt werden. Das Delir war mit einer signifikant l{\"a}ngeren Sedierungsdauer verbunden und Patienten mit Delir wiesen signifikant mehr Risikofaktoren f{\"u}r Delir auf. Der Erhebung von Risikofaktoren und der fr{\"u}hzeitigen Erkennung des Delirs kommen damit eine besondere Bedeutung zu. Eine korrekte Dokumentation ist aus rechtlichen Gesichtspunkten und aus Respekt vor dem Selbstbestimmungsrecht des Patienten sehr wichtig, hier gab es Verbesserungspotential. Eine Empfehlung zur strukturierten Durchf{\"u}hrung der palliativen Sedierungstherapie wurde von der Autorin entwickelt.},
  subject      = {Palliative Sedierung},
  language  = {de}
}
@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}
}