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Zusammenfassung: Durch weitreichende technische Weiterentwicklung der Strahlentherapie konnten in den letzten Jahren die Heilungsraten beim lokal fortgeschrittenen Prostatakarzinom deutlich gesteigert werden. Der Artikel fasst die entscheidenden Publikationen zur Dosiseskalation zusammen, erfasst die Nebenwirkungen und diskutiert den zusätzlichen Einsatz einer Hormontherapie oder der Bestrahlung der Lymphabflusswege.

Purpose: To show the feasibility of 3D-printed fixation masks for whole brain radiation therapy in a clinical setting and perform a first comparison to an established thermoplastic mask system. Methods: Six patients were irradiated with whole brain radiotherapy using individually 3D-printed masks. Daily image guidance and position correction were performed prior to each irradiation fraction. The vectors of the daily position correction were compared to two collectives of patients, who were irradiated using the standard thermoplastic mask system (one cohort with head masks; one cohort with head and neck masks). Results: The mean systematic errors in the experimental cohort ranged between 0.59 and 2.10 mm which is in a comparable range to the control groups (0.18 mm–0.68 mm and 0.34 mm–2.96 mm, respectively). The 3D-printed masks seem to be an alternative to the established thermoplastic mask systems. Nevertheless, further investigation will need to be performed. Conclusion: The prevailing study showed a reliable and reproducible interfractional positioning accuracy using individually 3D-printed masks for whole brain irradiation in a clinical routine. Further investigations, especially concerning smaller target volumes or other areas of the body, need to be performed before using the system on a larger basis.

This planning study was performed to compare stereotactic linac based radiosurgery of Arteriovenous Malformations (AVM) with current Helical Tomotherapy (HT) and future HT techniques. For 10 patients with AVM, dose distributions and treatment times of “regular” HT delivery (Reg 2.5/1/0.6 cm field width), Running-Start-Stop Treatment (RSS 5/2.5 cm), Axial Mode (Axial 5 cm) and Dynamic Jaw/Dynamic Couch delivery with a maximum field width of 5 cm (DJDC 5) were analysed and compared to linac-based stereotactic radiosurgery. Axial produced the fastest treatment (Axial 4:47 min vs. Linac 32:42 min) at the cost of large brain exposure (V10%289 ml). Except for Reg 0.6, all other HT techniques achieved significantly shorter treatment times than linac-based treatment (e.g.Reg 1, 19:42 min, DJDC 6:30 min). However, high-dose brain exposure (V60%) was higher in all HT plans (e.g.Reg 0.6, 10 ml, Linac 9 ml), and only Reg 0.6 showed better low-dose exposure (V10%of 167 ml vs. 199 ml, not significant). Neither current nor future HT modes in their current version outperformed linac-based stereotactic radiosurgery. However, AVM with special geometry might still benefit from HT.

Efforts have been made to extend the application of intensity-modulated radiotherapy to a variety of organs. One of the unanswered questions is whether breathing-induced organ motion may lead to a relevant over- or underdosage, e.g., in treatment plans for the irradiation of lung cancer. Theoretical considerations have been made concerning the different kinds of IMRT but there is still a lack of experimental data. We examined 18 points in a fraction of a clinical treatment plan of a NSCLC delivered in static IMRT with a new phantom and nine ionization chambers. Measurements were performed at a speed of 12 and 16 breathing cycles per minute. The dose differences between static points and moving target points ranged between −2.4% and +5.5% (mean: +0.2%, median: −0.1%) when moving with 12 cycles min⁻¹ and between −3.6% and +5.0% (mean: −0.4%, median: −0.6%) when moving with 16 cycles min⁻¹. All differences of measurements with and without movements were below 5%, with one exception. In conclusion, our results underline that at least in static IMRT breathing effects (concerning target dose coverage) due to interplay effects between collimator leaf movement and target movement are of secondary importance and will not reduce the clinical value of IMRT in the step-and-shoot technique for irradiation of thoracic targets.