Dosimetric integration of daily mega-voltage cone-beam CT for image-guided intensity-modulated radiotherapy.

PURPOSE: The goal of this work was to compare different methods of incorporating the additional dose of mega-voltage cone-beam CT (MV-CBCT) for image-guided intensity modulated radiotherapy (IMRT) of different tumor entities. MATERIAL AND METHODS: The absolute dose delivered by the MV-CBCT was calculated and considered by creating a scaled IMRT plan (scIMRT) by renormalizing the clinically approved plan (orgIMRT) so that the sum with the MV-CBCT dose yields the same prescribed dose. In the other case, a newly optimized plan (optIMRT) was generated by including the dose distribution of the MV-CBCT as pre-irradiation. Both plans were compared with the orgIMRT plan and a plan where the last fraction was skipped. RESULTS: No significant changes were observed regarding the 95% conformity index of the target volume. The mean dose of the organs at risk (OAR) increased by approx. 7% for the scIMRT plan and 5% for the optIMRT plan. A significant increase of the mean dose to the outline contour was observed, ranging from 3.1 ± 1.3% (optIMRT) to 13.0 ± 6.1% (scIMRT) for both methods over all entities. If the dose of daily MV-CBCT would have been ignored, the additional dose accumulated to nearly a whole treatment fraction with a general increase of approx. 10% to the OARs and approx. 4% to the target volume. CONCLUSION: Both methods of incorporating the additional MV-CBCT dose into the treatment plan are suitable for clinical practice. The dose distribution of the target volume could be achieved as conformal as with the orgIMRT plan, while only a moderate increase of mean dose to OAR was observed.

[Evaluation of time, attendance of medical staff, and resources during stereotactic radiotherapy/radiosurgery : QUIRO-DEGRO Trial].

BACKGROUND: The German Society of Radiation Oncology ("Deutsche Gesellschaft für Radioonkologie", DEGRO) initiated a multicenter trial to develop and evaluate adequate modules to assert core processes and subprocesses in radiotherapy. The aim of this prospective evaluation was to methodical assess the required resources (technical equipment and medical staff) for stereotactic radiotherapy/radiosurgery. MATERIAL AND METHODS: At two radiotherapy centers of excellence (University Hospitals of Heidelberg and Marburg/Giessen), the manpower and time required for the implementation of intra- and extracranial stereotactic radiotherapy was prospectively collected consistently over a 3-month period. The data were collected using specifically developed process acquisition tools and standard forms and were evaluated using specific process analysis tools. RESULTS: For intracranial (extracranial) fractionated stereotactic radiotherapy (FSRT) and radiosurgery (RS), a total of 1,925 (270) and 199 (36) records, respectively, could be evaluated. The approximate time needed to customize the immobilization device was median 37 min (89 min) for FRST and 31 min (26 min) for RS, for the contrast enhanced planning studies 22 and 27 min (25 and 28 min), for physical treatment planning 122 and 59 min (187 and 27 min), for the first and routine radiotherapy sessions for FSRT 40 and 13 min (58 and 31 min), respectively. The median time needed for the RS session was 58 min (45 min). The corresponding minimal manpower needed was 2 technicians for customization of the immobilization device, 2.5 technicians and 1 consultant for the contrast-enhanced planning studies, 1 consultant, 0.5 resident and 0.67 medical physics expert (MPE) for physical treatment planning, as well as 1 consultant, 0.5 resident, and 2.5 technicians for the first radiotherapy treatment and 2.33 technicians for routine radiotherapy sessions. CONCLUSION: For the first time, the resource requirements for a radiotherapy department for the maintenance, protection and optimization of operational readiness for the application of intra- and extracranial stereotactic radiotherapy was determined methodically.

Changes in AVM angio-architecture and hemodynamics after stereotactic radiosurgery assessed by dynamic MRA and phase contrast flow assessments: a prospective follow-up study.

OBJECTIVES: Assessment of changes in the hemodynamics of Arteriovenous malformations (AVM) induced by radiosurgery by MR Phase contrast (PC) measurements of the internal carotid arteries (ICA). METHODS: 65 patients shortly after or before stereotactic radiosurgery underwent MRI including morphological series, MR-Angiography (Time-of-flight, dynamic MRA) and bilateral ECG triggered MR phase contrast (PC) measurements of the ICA. Follow-up was performed in 34 patients. The observation period was up to 4 years. RESULTS: Over all subjects, a significant relationship between mean arterial blood flow in the ICA on the side of the lesion and AVM volume was revealed (p = 0,0002). In large (>10 ccm) and medium-sized AVMs, (>3, 5 ≤ 10 ccm) the blood flow was significantly increased on the side of the AVM (p = 0,0004; p = 0,047), whereas in lesions <3, 5 ccm, no significant rise of the mean blood flow was detectable. At follow-up, the mean blood flow in the ipsilateral artery was not increased anymore compared to the contralateral ICA (p = 0,11). These changes correlated with a significant reduction of the average AVM volume (p = 0, 0026). CONCLUSIONS: The AVM angioarchitecture has significant impact on the blood flow in feeding arteries. A significant reduction of the shunt volume by successful radiotherapy leads to normalization of the hemodynamics.

Tomotherapy radiosurgery for arteriovenous malformations--current possibilities and future options with helical tomotherapy dynamic jaws?

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.

[Postoperative radiotherapy of the chest wall in patients with male breast cancer]. / Postoperative Strahlentherapie der Thoraxwand beim Mammakarzinom des Mannes.

INTRODUCTION: We analysed our long-term results with postoperative radiotherapy of the chest wall in male breast cancer patients with respect to local control and survival. METHODS: Twenty-five patients with 26 histological proven carcinomas of the male breast underwent postoperative radiotherapy of the chest wall with (n = 15) or without regional lymphatics after mastectomy. Additionally 13 patients received adjuvant hormones and 3 patients adjuvant chemotherapy. Median age at treatment was 62.2 years (45.9-78.5 years). Median follow-up was 15.3 years (7.7-27.5 years). RESULTS: Overall survival after radiotherapy was 28 %, disease-specific survival was 64 %. Actuarial 3-, 5- and 10-year survival was 72 %, 56 % and 35 %. Median survival time was 6.1 years. Actuarial progression-free survival was 80 %, 52 % and 43 % after 3, 5 and 10 years, respectively. Local tumor control was 92 % (24 / 26). Survival was significantly affected by the presence of lymph node metastases (p < 0.01) and localisation of the tumor in the right breast (p < 0.04). CONCLUSION: Postoperative radiotherapy is an important part of the management of male breast cancer to improve local control and progression-free survival. The presence of lymph node metastases significantly impairs survival.