The lateral joint line opening: a radiographic indicative parameter for high grade varus knees

Purpose

It is usually assumed that the severity of varus osteoarthritis (OA) of the knee is correlated with the axis deviation of the limb. Despite this, there is currently no clear radiographic definition to define a so-called ‘high degree’ varus knee, which is characterized by a pronounced lateral ligamentous laxity. The purpose of this study was to radiographically determine if the lateral joint line opening (LJLO) is an indicative parameter when defining so-called high grade varus knees.

Methods

Two hundred forty Full length radiographs of patients with end-stage varus osteoarthritis who were scheduled for Total knee arthroplasty (TKA) were evaluated. The Hip-knee-ankle-angle (HKA-angle), Joint-line-convergence-angle (JLCA) and the lateral joint line opening were measured. The lateral joint line opening is the shortest distance between the lateral tibial plateau and the deepest point of the lateral femoral condyle. Linear regression models were used to investigate the relationships between the radiographic measurements.

Results

Hip-knee-angle-angle, joint-line-conversion-angle, and lateral joint line opening were all positively correlated (p < 0.001). An increase of 1 mm lateral joint line opening causes an increase of 0.6° joint-line-conversion-angle (p = 0.029) below a cut-off point of 4.7 mm. For lateral opening values beyond 4.7 mm, the gradient increased to 1.2 (p < 0.001). A lateral joint line opening of 4.7 mm corresponds to a hip-knee-ankle-angle of 6.0° (95% CI [5.5; 6.5]).

Conclusion

A lateral joint line opening of more than 5 mm in end-stage OA knees is indicative of increased lateral joint laxity. Those knees can be radiographically classified as so-called ‘high-grade’ varus knees.

Level of evidence

Therapeutic study, Level III.

“Radiotherapy for Thymic Epithelial Tumors: What Is The Optimal Dose? A Systematic Review.”

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Thymic epithelial tumors(TETs) often require a multimodal approach, including RT.

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RT dose recommendations largely derive from old data, where 2D RT was widely used.

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This systematic review focused on the optimal dose for TETs with modern RT.

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5 eligible studies reporting dose response were analyzed and synthesized.

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Current guidelines remain valid, this work might be an eye-opener fostering new data.

Thymic epithelial tumors (TETs) are rare thoracic tumors, often requiring multimodal approaches. Surgery represents the first step of the treatment, possibly followed by adjuvant radiotherapy (RT) and, less frequently, chemotherapy. For unresectable tumors, a combination of chemotherapy and RT is often used. Currently, the optimal dose for patients undergoing radiation is not clearly defined. Current guidelines on RT are based on studies with a low level of evidence, where 2D RT was widely used. We aim to shed light on the optimal radiation dose for patients with TETs undergoing RT through a systematic review of the recent literature, including reports using modern RT techniques such as 3D-CRT, IMRT/VMAT, or proton-therapy. A comprehensive literature search of four databases was conducted following the PRISMA guidelines. Two investigators independently screened and reviewed the retrieved references. Reports with < 20 patients, 2D-RT use only, median follow-up time < 5 years, and reviews were excluded. Two studies fulfilled all the criteria and therefore were included. Loosening the follow-up time criteria to > 3 years, three additional studies could be evaluated. A total of 193 patients were analyzed, stratified for prognostic factors (histology, stage, and completeness of resection), and synthesized according to the synthesis without meta-analysis (SWIM) method. The paucity and heterogeneity of eligible studies led to controversial results. The optimal RT dose neither for postoperative, nor primary RT in the era of modern RT univocally emerged. Conversely, this overview can spark new evidence to define the optimal RT dose for each TETs category.

Adcitmer® , a new CD56-targeting monomethyl auristatin E-conjugated antibody, is a potential therapeutic approach in Merkel cell carcinoma

BACKGROUND

Merkel cell carcinoma (MCC) is an aggressive skin cancer, whose tumour cells often express CD56. While immune checkpoint inhibitors constitute a major advance for treating patients with MCC with advanced disease, new therapeutic options are still urgently required.

OBJECTIVES

To produce and evaluate the therapeutic performance of a new antibody-drug conjugate (Adcitmer^® ) targeting CD56 in preclinical models of MCC.

METHODS

CD56 expression was evaluated in a MCC cohort (immunohistochemistry on a tissue microarray of 90 tumour samples) and MCC cell lines. Interaction of an unconjugated CD56-targeting antibody with CD56⁺ MCC cell lines was investigated by immunohistochemistry and imaging flow cytometry. Adcitmer^® product was generated by the bioconjugation of CD56-targeting antibody to a cytotoxic drug (monomethyl auristatin E) using the McSAF Inside^® bioconjugation process. The chemical properties and homogeneity of Adcitmer^® were characterized by hydrophobic interaction chromatography. Adcitmer^® cytotoxicity was evaluated in vitro and in an MCC xenograft mice model.

RESULTS

Similar to previous reports, CD56 was expressed by 66% of MCC tumours in our cohort, confirming its relevance as a therapeutic target. Specific binding and internalization of the unconjugated CD56-targeting antibody was validated in MCC cell lines. The high homogeneity of the newly generated Adcitmer^® was confirmed by hydrophobic interaction chromatography. The CD56-mediated cytotoxicity of Adcitmer^® was demonstrated in vitro in MCC cell lines. Moreover, Adcitmer^® significantly reduced tumour growth in a MCC mouse model.

CONCLUSIONS

Our study suggests that Adcitmer^® should be further assessed as a therapeutic option in patients with MCC, as an alternative therapy or combined with immune checkpoint inhibitors.

Monitoring health and well-being of children and adolescents in Germany since 2003

Background

KiGGS - the German Health Interview and Examination Survey for Children and Adolescents is part of the German health monitoring framework providing data analyses and recommendations for politics based on own primary data collection and secondary data from other sources. In 1998, the Robert Koch Institute was commissioned by the Federal Ministry of Health to develop approaches and instruments for a health survey for children and adolescents aged 0 to 17 years.

Methods

KiGGS is conducted at regular intervals and acts as a central source of information that collects wide-ranging, reliable data on child and adolescent health. KiGGS comprises a cross-sectional and a longitudinal component. Until now, three nationally representative surveys have been performed: KiGGS baseline (2003-2006), Wave 1 (2009-2012) and Wave 2 (2014-2017). The baseline sample comprises 17,641 children and adolescents. The KiGGS cohort is the longitudinal component of the study. To date, two follow-ups have been accomplished.

Results

The repeated cross-sectional surveys have provided a profound data basis in order to calculate prevalences and conduct context analyses for each period and identifying changes over time in physical and mental health status, health behaviour, utilisation of health care services and prevention as well as social, family and environmental factors. Additionally, the longitudinal data enable to analyse developments in health and their influencing factors during the life course. Reports and recommendations based on KiGGS data have been useful to support the implementation of national health programs for children and adolescents, e.g. for the prevention of childhood obesity.

Conclusions

Regular health interview and examination surveys are necessary to provide reliable data to derive recommendations for health politics. Furthermore, they offer a robust method to evaluate actions taken to prevent illness and promote positive health behaviour on the population level.

Reliability of the intracerebral hemorrhage score for predicting outcome in patients with intracerebral hemorrhage using oral anticoagulants

BACKGROUND AND PURPOSE

The intracerebral hemorrhage (ICH) score is the most widely used and validated prognostic model for estimating 30-day mortality in ICH. However, the score was developed and validated in an ICH population probably not using oral anticoagulants (OACs). The aim of this study was to determine the performance of the ICH score for predicting the 30-day mortality rate in the full range of ICH scores in patients using OACs.

METHODS

Data from admitted patients with ICH were collected retrospectively in two Dutch comprehensive stroke centers. The validity of the ICH score was evaluated by assessing both discrimination and calibration in OAC and OAC-naive patient groups.

RESULTS

A total of 1752 patients were included of which 462 (26%) patients were on OAC. The 30-day mortality was 54% for the OAC cohort and 34% for the OAC-naive cohort. The 30-day mortality was higher in the OAC cohort for ICH score 1 (33% vs. 12.5%; odds ratio, 3.4; 95% confidence intervals, 1.1-10.4) and ICH score 2 (53% vs. 26%; odds ratio, 3.2; 95% confidence intervals, 1.2-8.2) compared with the predicted mortality rate of the original ICH score. Overall, the discriminative ability of the ICH score was equally good in both cohorts (area under the curve 0.83 vs. 0.87, respectively).

CONCLUSIONS

The ICH score underestimated the 30-day mortality rate for lower ICH scores in OAC-ICH. When estimating the prognosis of ICH in patients using OAC, this underestimation of mortality must be taken into account.

Das Merkelzellkarzinom: Ätiopathogenese und Management

Das Merkelzellkarzinom (MCC) ist ein seltenes Malignom mit neuroendokriner Differenzierung, an dem v. a. ältere und immunsupprimierte Patienten erkranken. Die Inzidenz des Tumors nimmt weiter zu; die Prognose ist mit einer 5-Jahres-Überlebensrate von 0 – 18 % im Stadium III und IV schlecht. Ein Zusammenhang mit dem Merkelzell-Polyoma-Virus oder einer vermehrten UV-Exposition gelten als gesichert. Das MCC präsentiert sich als solitärer, derber, kuppelförmiger, schnell wachsender Tumor. Die Diagnose wird mittels histologischer und immunhistochemischer Untersuchungen gestellt. 2017 wurde von der UICC eine neue Stadieneinteilung basierend auf der TNM-Klassifikation erstellt. Die Prognose ist stark abhängig vom Tumorstadium bei Erstdiagnose, weshalb entsprechende Staginguntersuchungen durchgeführt werden sollten. Therapeutisch steht, sofern möglich, die komplette Exzision des Tumors mit ausreichendem Sicherheitsabstand und ggf. die Exstirpation von Lymphknotenmetastasen im Vordergrund. Anschließend sollte eine Radiatio des Tumorbetts und der Lymphabflussbahnen erfolgen. In metastasierten Stadien hat sich in den letzten Jahren die Immuntherapie als Therapie der Wahl herauskristallisiert; die Chemotherapie spielt seitdem eine zunehmend geringere Rolle. So zeigten prospektive Studien mit Pembrolizumab vielversprechende Ergebnisse mit einer Ansprechrate von 56 % und einem progressionsfreien Überleben nach 6 Monaten von 67 %. Seit Oktober 2017 ist mit Avelumab, einem anti-PD-L1-Antikörper, die erste Immuntherapie zur Behandlung des metastasierten MCC in Deutschland zugelassen. Da die Therapie des metastasierten MCC trotz dieser innovativen Behandlungsansätze auch weiterhin als palliativ anzusehen ist, sollten frühzeitig zusätzlich palliative und psychoonkologische Therapiekonzepte miteinbezogen werden. Nach abgeschlossener Tumortherapie sollten regelmäßige Nachsorgeuntersuchungen erfolgen, um frühzeitig Rezidive oder Metastasen zu detektieren.

Modelling the impact of social protection on tuberculosis: the S-PROTECT project

Background

Tackling the social determinants of Tuberculosis (TB) through social protection is a key element of the post-2015 End TB Strategy. However, evidence informing policies are still scarce. Mathematical modelling has the potential to contribute to fill this knowledge gap, but existing models are inadequate. The S-PROTECT consortium aimed to develop an innovative mathematical modelling approach to better understand the role of social protection to improve TB care, prevention and control.

Methods

S-PROTECT used a three-steps approach: 1) the development of a conceptual framework; 2) the extraction from this framework of three high-priority mechanistic pathways amenable for modelling; 3) the development of a revised version of a standard TB transmission model able to capture the structure of these pathways. As a test case we used the Bolsa Familia Programme (BFP), the Brazilian conditional cash transfer scheme.

Results

Assessing one of these pathways, we estimated that BFP can reduce TB prevalence by 4% by improving households income and thus their nutritional status. When looking at the direct impact via malnutrition (not income mediated) the impact was 33%. This variation was due to limited data availability, uncertainties on data transformation and the pathway approach taken. These results are preliminary and only aim to serve as illustrative example of the methodological challenges encountered in this first modelling attempt, nonetheless they suggest the potential added value of integrating TB standard of care with social protection strategies.

Conclusions

Results are to be confirmed with further analysis. However, by developing a generalizable modelling framework, S-PROTECT proved that the modelling of social protection is complex, but doable and allowed to draw the research road map for the future in this field.

Electronic supplementary material

The online version of this article (10.1186/s12889-018-5539-x) contains supplementary material, which is available to authorized users.

Comprehensive assessment of food and nutrient intake of children and adolescents in Germany: EsKiMo II - the eating study as a KiGGS module

Background

As part of the second wave of the German Health Interview and Examination Survey for Children and Adolescents (KiGGS Wave 2), food and nutrient intake of children and adolescents aged 6–17 years living in Germany is assessed in EsKiMo II – the Eating Study as a KiGGS Module.

Methods

EsKiMo II is a cross-sectional study, conducted from June 2015 until September 2017. The study population comprises 6 to 17-year-old study participants from the cross-sectional sample of KiGGS Wave 2 in 167 KiGGS sample points, which are revisited by trained nutritionists. Dietary intake is assessed by weighted food records during three consecutive days plus one randomly selected day within the following 3 months for children aged 6–11 years. Dietary intake for adolescents aged 12–17 years is assessed by computer-assisted dietary history interviews, reflecting the past four weeks, using the software DISHES. Further information, for example, about specific diets and dietary supplement intake, is reported during a standardised computer assisted interview for all participants. Food items are coded by the German Food Code and Nutrient Database (BLS 3.02).

Discussion

EsKiMo II provides actual data on the dietary behaviour of children and adolescents living in Germany and their determinants. Results of EsKiMo II will be relevant for decision-making, measures, and evaluations within nutrition, consumer and health policy.

Pathofysiologie van lipopolysaccharide geïnduceerde inflammatoire respons bij vogels

Inflammatie is een beschermende respons op infectie en/of weefselschade die gepaard gaat met de migratie van immuuncellen en mediatoren van de circulatie naar het betreffende weefsel. Deze respons dient om de initiële noxe (onder andere lipopolysaccharide of LPS) te verwijderen en genezing en herstel van het beschadigde weefsel te bekomen. LPS is een onderdeel van de buitenste celmembraan van gramnegatieve bacteriën dat pro-inflammatoire eigenschappen heeft en na toediening bij vogels een ontstekingsreactie teweegbrengt. Deze ontstekingsreactie gaat gepaard met onder andere veranderingen in lichaamstemperatuur, de productie van pro-inflammatoire cytokinen en vorming van acutefase-eiwitten, leukocytose en ziektegedrag. In welke mate elk van deze symptomen aanwezig is bij vogels hangt af van de vogelsoort. Bovendien zijn er verschillen met zoogdieren. De karakteristieken en pathofysiologische gevolgen van een ontstekingsreactie worden vaak bestudeerd in LPS-inflammatiemodellen. Deze inflammatiemodellen kunnen vervolgens toegepast worden in farmacodynamiekstudies om het klinisch effect van anti-inflammatoire geneesmiddelen, zoals niet-steroïdale ontstekingsremmers (NSAIDs) te beoordelen. In dit artikel wordt een overzicht gegeven van de LPS-geïnduceerde inflammatoire respons bij vogels.

Farmacokinetiek van geneesmiddelen bij vogels en de toepassingen en beperkingen van dosisextrapolatie

De farmacokinetische processen van geneesmiddelen, i.e. absorptie, distributie, metabolisatie en excretie, kunnen sterk verschillen tussen vogels en zoogdieren. Zo worden aminoglycosiden bij vogels trager geklaard en hebben een lager distributievolume dan bij zoogdieren. Deze farmacokinetische verschillen zijn hoofdzakelijk het gevolg van anatomische, biochemische en fysiologische verschillen tussen vogels en zoogdieren. Deze diersoortverschillen en verschillen in geobserveerde en voorspelde farmacokinetische parameters van geneesmiddelen bij vogels geëxtrapoleerd vanuit zoogdieren, zoals de klaring voor enrofloxacine, salicylzuur, meloxicam en flunixine, wijzen erop dat farmacokinetische gegevens van een geneesmiddel bij zoogdieren nauwelijks geëxtrapoleerd kunnen worden naar vogels. Ook tussen vogelsoorten onderling kunnen er verschillen aanwezig zijn. Indien mogelijk dient de dosisselectie van een geneesmiddel voor vogels bijgevolg te gebeuren op basis van de farmacokinetische gegevens van de desbetreffende vogelsoort. Indien dergelijke gegevens niet beschikbaar zijn, kan er gebruik gemaakt worden van allometrische schaling, waarbij de dosisselectie gebeurt op basis van de farmacokinetische gegevens van een andere vogelsoort gecorreleerd aan het lichaamsgewicht van deze vogelsoorten. Schaling op basis van zoogdiergegevens wordt slechts aangeraden indien de farmacokinetische gegevens van andere vogelsoorten niet beschikbaar zijn en het betreffende geneesmiddel een lage toxiciteit heeft.

Impact and cost-effectiveness of current and future tuberculosis diagnostics: the contribution of modelling

The landscape of diagnostic testing for tuberculosis (TB) is changing rapidly, and stakeholders need urgent guidance on how to develop, deploy and optimize TB diagnostics in a way that maximizes impact and makes best use of available resources. When decisions must be made with only incomplete or preliminary data available, modelling is a useful tool for providing such guidance. Following a meeting of modelers and other key stakeholders organized by the TB Modelling and Analysis Consortium, we propose a conceptual framework for positioning models of TB diagnostics. We use that framework to describe modelling priorities in four key areas: Xpert^® MTB/RIF scale-up, target product profiles for novel assays, drug susceptibility testing to support new drug regimens, and the improvement of future TB diagnostic models. If we are to maximize the impact and cost-effectiveness of TB diagnostics, these modelling priorities should figure prominently as targets for future research.

Association between eye position on brain scan and hospital mortality in acute intracerebral hemorrhage

BACKGROUND AND PURPOSE

Conjugate eye deviation (CED) and horizontal skew deviation are often seen in patients with intracerebral hemorrhage (ICH), but its prognostic significance is unclear. In this study, the association between brain scan assessed eye position and hospital mortality in patients with supratentorial ICH was tested.

METHODS

A retrospective analysis was performed in 316 patients with supratentorial ICH. Eye position was measured on first brain computed tomography or magnetic resonance imaging. Patients with CED, horizontal skew deviation or no deviation were distinguished. The association between eye position and hospital mortality was assessed using logistic regression analysis.

RESULTS

Conjugate eye deviation was present in 96 (30.4%), skew deviation in 44 (13.9%) and no deviation in 176 (55.7%) patients. In patients with CED, 81.3% had an eye position to the ipsilateral side of the hemorrhage. In univariable regression analysis, skew deviation was associated with mortality (odds ratio 3.10, 95% confidence interval 1.57-6.11; P = 0.001). In multivariable regression analysis, adjusting for age, ICH volume, intraventricular extension and Glasgow Coma Scale, eye position was not independently associated with mortality.

CONCLUSION

Horizontal skew eyes were found to be an unfavorable prognostic factor. However, this was not independent of other important predictors of ICH mortality and is most probably explained by its association with worse initial clinical presentation.

Organizational development trajectory of a large academic radiotherapy department set up similarly to a prospective clinical trial: the MAASTRO experience

Objective:

To simultaneously improve patient care processes and clinical research activities by starting a hypothesis-driven reorganization trajectory mimicking the rigorous methodology of a prospective clinical trial.

Methods:

The design of this reorganization trajectory was based on the model of a prospective trial. It consisted of (1) listing problems and analysing their potential causes, (2) defining interventions, (3) defining end points and (4) measuring the effect of the interventions (i.e. at baseline and after 1 and 2 years). The primary end point for patient care was the number of organizational root causes of incidents/near incidents; for clinical research, it was the number of patients in trials. There were several secondary end points. We analysed the data using two sample z-tests, χ² test, a Mann–Whitney U test and the one-way analysis of variance with Bonferroni correction.

Results:

The number of organizational root causes was reduced by 27% (p < 0.001). There was no effect on the percentage of patients included in trials.

Conclusion:

The reorganizational trajectory was successful for the primary end point of patient care and had no effect on clinical research. Some confounding events hampered our ability to draw strong conclusions. Nevertheless, the transparency of this approach can give medical professionals more confidence in moving forward with other organizational changes in the same way.

Advances in knowledge:

This article is novel because managerial interventions were set up similarly to a prospective clinical trial. This study is the first of its kind in radiotherapy, and this approach can contribute to discussions about the effectiveness of managerial interventions.

EGFR mutated non-small cell lung cancer patients: more prone to development of bone and brain metastases?

OBJECTIVES

Both bone and brain are frequent sites of metastasis in non-small cell lung cancer (NSCLC). Conflicting data exist whether EGFR mutant (+) patients are more prone to develop brain metastases or have a better outcome with brain metastases compared to EGFR/KRAS wildtype (WT) or KRAS+ patients. For bone metastases this has not been studied.

METHODS

In this retrospective case-control study all EGFR+ (exons 19 and 21) patients diagnosed at two pathology departments were selected (2004/2008 to 2012). For every EGFR+ patient a consecutive KRAS+ and WT patient with metastatic NSCLC (mNSCLC) was identified. Patients with another malignancy within 2 years of mNSCLC diagnosis were excluded. Data regarding age, gender, performance score, histology, treatment, bone/brain metastases diagnosis, skeletal related events (SRE) and subsequent survival were collected.

RESULTS

189 patients were included: 62 EGFR+, 65 KRAS+, 62 WT. 32%, 35% and 40%, respectively, had brain metastases (p=0.645). Mean time to brain metastases was 20.8 [± 12.0], 10.8 [± 9.8], 16.4 [± 10.2] months (EGFR+-KRAS+, p = 0.020, EGFR+-WT, p = 0.321). Median post brain metastases survival was 12.1 [5.0-19.1], 7.6 [1.2-14.0], 10.7 [1.5-19.8] months (p = 0.674). 60%, 52% and 50% had metastatic bone disease (p=0.528). Mean time to development of metastatic bone disease was 13.4 [± 10.6], 23.3 [± 19.4], 16.4 [± 9.6] months (p = 0.201). Median post metastatic bone disease survival was 15.0 [10.6-20.3], 9.0 [5.2-12.9], 3.2 [0.0-6.9] months (p = 0.010). Time to 1st SRE was not significantly different.

CONCLUSIONS

Incidence of brain and bone metastases was not different between EGFR+, KRAS+ and WT patients. Post brain metastases survival, time from mNSCLC diagnosis to metastatic bone disease and 1st SRE did not differ either. Post metastatic bone disease survival was significantly longer in EGFR+ patients. Although prevention of SRE's is important for all patients, the latter finding calls for a separate study for SRE preventing agents in EGFR+ patients.

P-cadherin expression in Merkel cell carcinomas is associated with prolonged recurrence-free survival

BACKGROUND

 Merkel cell carcinoma (MCC) is a highly aggressive skin cancer, associated with advanced age, immunosuppression and Merkel cell polyomavirus (MCV) infections. As development and progression of cancer can be promoted by changes in cell adhesion proteins, we have previously analysed homo- and heterotypic cell-cell contacts of normal Merkel cells and MCCs and obtained indications for cadherin switching.

OBJECTIVES

To examine the prevalence and prognostic relevance of E-, N- and P-cadherin in MCCs.

METHODS

Paraffin-embedded MCC samples (n = 148) from 106 different patients were analysed by double-label immunostaining and immunofluorescence microscopy. MCV status was determined by real-time polymerase chain reaction. The cadherin repertoire and MCV status were correlated to clinical data, including tumour stage and recurrence-free survival.

RESULTS

Ninety-one per cent of all MCC were positive for N-cadherin whereas only 61·6% and 70·3% expressed E- and P-cadherin, respectively. P-cadherin was significantly more frequent in primary tumours than in lymph node metastases (81·9% vs. 40·9%, P = 0·0002). Patients with P-cadherin-positive primary tumours were in earlier tumour stages at initial diagnosis (P = 0·0046). Both in log-rank tests (P = 0·0474) and in multiple Cox regression analysis including age, sex, immunosuppression, stage at initial diagnosis and MCV status (hazard ratio 0·193, P = 0·0373), patients with P-cadherin-positive primary MCCs had significantly prolonged recurrence-free survival (mean 25·2 vs. 10·6 months; median 9·0 vs. 4·0 months). MCV DNA was detected in 78·2% of all MCC, more frequently in P-cadherin-positive MCC (P = 0·0008).

CONCLUSION

P-cadherin expression in MCCs predicts prolonged recurrence-free survival and may therefore indicate favourable prognosis.

Relocatable fixation systems in intracranial stereotactic radiotherapy. Accuracy of serial CT scans and patient acceptance in a randomized design

PURPOSE

The goal was to provide a quantitative evaluation of the accuracy of three different fixation systems for stereotactic radiotherapy and to evaluate patients' acceptance for all fixations.

METHODS

A total of 16 consecutive patients with brain tumours undergoing fractionated stereotactic radiotherapy (SCRT) were enrolled after informed consent (Clinical trials.gov: NCT00181350). Fixation systems evaluated were the BrainLAB® mask, with and without custom made bite-block (fixations S and A) and a homemade neck support with bite-block (fixation B) based on the BrainLAB® frame. The sequence of measurements was evaluated in a randomized manner with a cross-over design and patients' acceptance by a questionnaire.

RESULTS

The mean three-dimensional (3D) displacement and standard deviations were 1.16 ± 0.68 mm for fixation S, 1.92 ± 1.28 and 1.70 ± 0.83 mm for fixations A and B, respectively. There was a significant improvement of the overall alignment (3D vector) when using the standard fixation instead of fixation A or B in the craniocaudal direction (p = 0.037). Rotational deviations were significantly less for the standard fixation S in relation to fixations A (p = 0.005) and B (p = 0.03). EPI imaging with off-line correction further improved reproducibility. Five out of 8 patients preferred the neck support with the bite-block.

CONCLUSION

The mask fixation system in conjunction with a bite-block is the most accurate fixation for SCRT reducing craniocaudal and rotational movements. Patients favoured the more comfortable but less accurate neck support. To optimize the accuracy of SCRT, additional regular portal imaging is warranted.