No abstract

In this review we summarize the currently available evidence about the role of hybrid machines for MR-guided radiotherapy for prostate stereotactic body radiotherapy. Given the novelty of this technology, to date few data are accessible, but they all report very promising results in terms of tolerability and preliminary clinical outcomes. Most of the studies highlight the favorable impact of on-board magnetic resonance imaging as a means to improve target and organs at risk identification with a consequent advantage in terms of dosimetric results, which is expected to relate to a more favorable toxicity pattern. Still, the longer treatment time per session may potentially affect the patient’s compliance to the treatment, although first quality of life assessment studies have reported substantial tolerability and no major impact on quality of life. Finally, in this review we hypothesize some future scenarios of further investigation, based on the possibility to explore the superior anatomy visualization and the role of daily adapted treatments provided by hybrid MR-Linacs.

To analyse the pattern of recurrence of patients treated with Stupp protocol in relation to technique, to compare in silico plans with reduced margin (1 cm) with the original ones and to analyse toxicity. 105 patients were treated: 85 had local recurrence and 68 of them were analysed. Recurrence was considered in field, marginal and distant if >80 %, 20-80 % or <20 % of the relapse volume was included in the 95 %-isodose. In silico plans were retrospectively recalculated using the same technique, fields angles and treatment planning system of the original ones. The pattern of recurrence was in field, marginal and distant in 88, 10 and 2 % respectively and was similar in in silico plans. The margin reduction appears to spare 100 cc of healthy brain by 57 Gy-volume (p = 0.02). The target coverage was worse in standard plans (pt student < 0.001), especially if the tumour was near to organs at risk (pχ2 < 0.001). PTV coverage was better with IMRT and helical-IMRT, than conformal-3D (pAnova test = 0.038). This difference was no more significant with in silico planning. A higher incidence of asthenia and leuko-encephalopathy was observed in patients with greater percentage of healthy brain included in 57 Gy-volume. No differences in the pattern of recurrence according to margins were found. The margin reduction determines sparing of healthy brain and could possibly reduce the incidence of late toxicity. Margin reduction could allow to use less sophisticated techniques, ensuring appropriate target coverage, and the choice of more costly techniques could be reserved to selected cases.

BackgroundTo compare and evaluate the possible advantages related to the use of VMAT and helical IMRT and two different modalities of boost delivering, adjuvant stereotactic boost (SRS) or simultaneous integrated boost (SIB), in the treatment of brain metastasis (BM) in RPA classes I-II patients.MethodsTen patients were treated with helical IMRT, 5 of them with SRS after whole brain radiotherapy (WBRT) and 5 with SIB. MRI co-registration with planning CT was mandatory and prescribed doses were 30 Gy in 10 fractions (fr) for WBRT and 15Gy/1fr or 45Gy/10fr in SRS or SIB, respectively. For each patient, 4 “treatment plans” (VMAT SRS and SIB, helical IMRT SRS and SIB) were calculated and accepted if PTV boost was included in 95 % isodose and dose constraints of the main organs at risk were respected without major deviations. Homogeneity Index (HI), Conformal Index (CI) and Conformal Number (CN) were considered to compare the different plans. Moreover, time of treatment delivery was calculated and considered in the analysis.ResultsVolume of brain metastasis ranged between 1.43 and 51.01 cc (mean 12.89 ± 6.37 ml) and 3 patients had double lesions. V95% resulted over 95 % in the average for each kind of technique, but the “target coverage” was inadequate for VMAT planning with two sites. The HI resulted close to the ideal value of zero in all cases; VMAT-SIB, VMAT-SRS, Helical IMRT-SIB and Helical IMRT-SRS showed mean CI of 2.15, 2.10, 2.44 and 1.66, respectively (optimal range: 1.5–2.0). Helical IMRT-SRS was related to the best and reliable finding of CN (0.66). The mean of treatment time was 210 s, 467 s, 440 s, 1598 s, respectively, for VMAT-SIB, VMAT-SRS, Helical IMRT-SIB and Helical IMRT-SRS.ConclusionsThis dosimetric comparison show that helical IMRT obtain better target coverage and respect of CI and CN; VMAT could be acceptable in solitary metastasis. SIB modality can be considered as a good choice for clinical and logistic compliance; literature’s preliminary data are confirming also a radiobiological benefit for SIB. Helical IMRT-SRS seems less effective for the long time of treatment compared to other techniques.

In the September 2017 on-line issue of La Radiologia Medica, Splendiani et al. published a clinical study on the effects of multiple injections of the macrocyclic GBCAs gadoterate meglumine and gadobutrol on dentate nuclei T1-weighted signal intensities (SI) in patients with multiple sclerosis [1]. In the abstract, the authors concluded: "SI increases on unenhanced T1-weighted images possibly indicative of gadolinium retention occur after serial administrations of the macrocyclic GBCAs, gadoterate meglumine and gadobutrol". This conclusion is, however, not supported by the results presented in the core of the article and the abstract.The authors showed an increase in dentate nucleusto-pons (DNP) SI ratio of extremely limited amplitude: 0.0032 ± 0.0216 for gadoterate meglumine and 0.0019 ± 0.0346 for gadobutrol. This increase was shown to be non-significant, as stated in the results section and in Fig. 3: "in neither case (gadoterate meglumine and gadobutrol) was the difference significantly different from 0 (P > 0.01)".The means of the DNP SI ratios were extremely close to the minimum and far from the maximum of the 95% confidence intervals: mean [min; max] were 0.0032 [0.0025; 0.0495] for gadoterate meglumine and 0.0019 [0.0017; 0.0235] for gadobutrol. Therefore, it is likely that the values within these intervals did not follow a normal Gaussian distribution and that the statistical tests used for comparisons were not appropriate.Furthermore, the authors compared their results with those of Radbruch et al. [2] and Weberling et al. [3]. They concluded that "linear regression revealed overall similarity between our findings and those of other authors regarding macrocyclic GBCAs". The publications referenced for comparison found no significant effect on the DNP SI ratio with macrocyclic GBCAs, even following multiple injections.Contrary to these previous publications, the authors mentioned a visible T1-weighted hyperintensity in approximately one third of the patients. No specific analyses were performed to correlate hyperintensities and numbers of injections. Interestingly, the example shown in Fig. 4a, b is from a patient who received the highest level of injections, and the signal was already visible in the DN prior to injection of gadoterate meglumine.We would also like to highlight several inaccuracies or mistakes along the publication such as the use of gadoteridol name instead of gadoterate meglumine in the results section, the nonscientific representation of the Fig. 3 which shows the means of SI ratios without error bars and whose scale should be extended by a factor 10 to include such error bars, and finally the inconsistency regarding the maximum number of gadobutrol injections in Table 1 compared to the results Sections (14 vs. 15).To conclude, we consider that Splendiani et al. should have been cautious and consistent in their conclusions, as they were not fully supported by their results. The data reported in this article confirm the previous studies, showing no evidence of gadolinium retention in b...

IntroductionMedulloblastoma, the most frequent brain tumor in childhood, also occurs with a wide range of characteristics in adult patients. Late relapse is common in adult medulloblastoma, and the overall survival of relapsed patients usually ranges from 12 to 15 months. Treatment at recurrence is still debated and after reoperation includes stereotactic or normofractionated radiotherapy, and high-dose chemotherapy with autologous bone marrow transplantation.Case presentationWe report on the case of a 31-year-old Caucasian woman who underwent re-irradiation for a recurrence of medulloblastoma at nine years after first irradiation (56Gy), focusing on the radiobiological background and a review of previous studies involving re-irradiation of recurrent medulloblastoma. After surgical excision of the relapsed tumor and medical multi-agent treatment, the site of recurrence was treated using three-dimensional conformal radiotherapy to a total dose of 52.8Gy (1.2Gy/fraction/twice daily). A total biological equivalent dose of 224.6Gy (α:β = 2 Gy) was delivered to the posterior fossa (first and second treatments). No radionecrosis or local recurrence was evident at 18 months after re-irradiation.ConclusionRe-irradiation can be considered a possible and safe treatment in selected cases of recurrent medulloblastoma in adults. The reported radiobiological considerations could be useful in other cases involving re-irradiation of brain tumors.

This paper is an initial study to evaluate the effectiveness of the IFRD. The method is fast, painless, inexpensive, and it appears to be suitable as a routine treatment. The presented data support the conclusions at this stage and warrant more comprehensive evaluation.

The combination of enzalutamide with ionizing radiation significantly improves radio-sensitivity of hormone-dependent LNCaP cells. Translated in the clinical practice, our results may help to find additional strategies to improve effectiveness of radiotherapy.