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Flattening filter free (FFF) high dose rate beam technique was introduced for brain stereotactic radiosurgery (SRS) and lung Stereotactic Body Radiotherapy (SBRT). Furthermore, a HexaPOD treatment table was introduced for the brain SRS to enable correction of rotational setup errors. 19 filter flattened (FF) and 57 FFF brain SRS treatments, as well as 451 FF and 294 FFF lung SBRT treatments were evaluated to assess differences in intrafractional motion (IFM) between FF and FFF treatments. For brain SRS the accuracy of rotational corrections was assessed as well. For SRS the treatment time was reduced by 21%, and for SBRT the treatment time was reduced by 25%. However, only for SBRT the IFM was significantly reduced, from 1.9 mm to 1.6 mm. For brain SRS, table correction in 6D greatly improves patient setup precision observed as a reduction in mean residual rotational setup error from 0.3 degrees (SD1.2 degrees) to 0.06 degrees (SD 0.3 degrees).

Introduction: Salivary glands are often involved in the high dose field during radiotherapy for head and neck cancer. Depending on dose prescription, a subjective feeling of oral dryness (xerostomia) may occur, being one of the most invalidating and rarely reversible late side effects. Objectives: We aimed to explore the ability to increase residual salivary flow from the parotid and submandibular salivary glands (MSG), considering the mean radiation dose given to them. Methods: Thirty one patients, 2-8 month after completed curative intended radiotherapy for HNC, were included. An EORTC H&N35-inspired questionnaire was used to evaluate the subjective complains of salivary function. The objective salivary gland function was measured as mean saliva flow rate (g/min) before and after mechanical stimulus by tasteless sugar free chewing gum. Mean doses (DMean) given to the four MSG were extracted from the radiotherapy planning system. Results: No relation between xerostomia and radiation dose were found, whereas subjective feeling of enough saliva to chew and swallow food was correlated to DMean received by MSG (p=0.05). DMean given to the four MSG correlated to the ability to increase salivary flow (g/min) of salivary when stimulated with tasteless chewing gum (p=0.07) (Figure). Conclusions: The results of this pilot-study show that both subjective and objective post-radiotherapy salivary gland functions are dependent of DMean given to the four MSG. Data suggests that involvement of the salivary glands affects the ability to stimulate vital residual salivary gland function, but that it is possible to increase it with additional mechanical stimuli.

Purpose/Objective: New national guidelines (GL) for radiotherapy (RT) of head and neck cancer (HNC) were implemented at the beginning of 2013. One purpose of the new GL was to nationally standardise the expansion from GTV to high risk CTV (CTV1). This standardisation has resulted in change of volume of CTV1 for most institutions which previously used different margins. Change in CTV1 volume definition could influence the risk and time evolution of adverse effects e.g. mucositis. This study investigates change in acute response during RT in a centre where GTV to CTV1 margin was increased from 0 to 5mm. Materials and Methods: All patients (n=592) receiving curative RT for HNC from Jan 2011 to Sep 2014 were included, 292 patients treated according to the old GL and 300 according to the new GL. Tumour doses were 66-68 Gy in 33-34 fx with 5 or 6/10 fx/w. All were treated with IMRT except for simple glottic tumours. Acute skin and mucosal reactions were scored weekly during RT, and 2 and 8 weeks after (0 none, 1 erythema, 2 dry desquamation/patchy mucositis, 3 wet desquamation/confluent mucositis, 4 ulceration). Use of analgesics was recorded equivalently on a 5-point scale. Clinical endpoints were dichotomized, grade 0- 1 vs 2+ or 0-2 vs 3+. Potential change in actuarial cumulative incidence (One minus the Kaplan Meier estimator) of mucositis was tested using the log-rank test. To stratify for the potential effect between non-accelerated (5 fx/w) and accelerated (6/10 fx/w) treatments, a Cox regression analysis including the covariates: acceleration, old/new GL, and their interaction product was performed. Potential differences between patient demographics were tested using a chi-square test. Results: The new GL increased the risk of grade 2+ mucositis during RT (p = 0.02) as demonstrated by a ~20%-point increase at the end of RT for the non-accelerated group, but not in the accelerated group. In Cox regression, all covariates were significantly associated with grade 2+ and 3+ mucositis (acceleration, p

When implementing new technology into clinical practice, there will always be a need for large knowledge gain. The aim of this study was twofold, (I) audit the treatment planning and dose delivery of Flattening Filter Free (FFF) beam technology for Stereotactic Body Radiation Therapy (SBRT) of lung tumours across a range of treatment planning systems compared to the conventional Flatting Filter (FF) beams, (II) investigate how sharing knowledge between centres of different experience can improve plan quality. All vendor/treatment planning system (TPS) combinations investigated were able to produce acceptable treatment plans and the dose accuracy was clinically acceptable for all plans. By sharing knowledge between the different centres, the minor protocol violations (MPV) could be significantly reduced, from an average of 1.9 MPV per plan to 0.6 after such sharing of treatment planning knowledge. In particular, for the centres with less SBRT and/or volumetric- modulated arc therapy (VMAT) experience the MPV average per plan improved. All vendor/TPS combinations were also able to successfully deliver the FF and FFF SBRT VMAT plans. The plan quality and dose accuracy were found to be clinically acceptable.

Purpose/Objective: It has been demonstrated that nonadherence to protocol-specified radiotherapy (RT) requirements is associated with reduced survival, local control and potentially increased toxicity [1]. Thus, quality assurance (QA) of RT is important when evaluating the results of clinical trials. RT-QA of large multicentre-trials, however, requires substantial effort and resources. Recently, we presented a digital QA platform, the CIRRO dose plan bank, which allows for central review of such trials. Here, we present our RT-QA results from the latest completed clinical protocol from the Danish Head and Neck Cancer Group (DAHANCA). Materials and Methods: The clinical results of the DAHANCA 19 randomized phase III trial evaluated the effect of concurrent EGFR-inhibition during primary curative (chemo) radiotherapy in patients with head and neck squamous cell carcinoma (HNSCC). A total of 504 Danish patients entered the protocol in 2007-2012. Patients received RT at 5 different oncology centers to a total dose of 66-68Gy, 2Gy/fx, 6 fx/week. For the current QA analysis, total treatment time, CTV coverage, and near-max doses to the spinal cord and brainstem including the corresponding planning risk volumes (PRVs) were evaluated according to 2004 DAHANCA guidelines. Each QA parameter was scored within three categories: 1) Full compliance to protocol guidelines, 2) Minor deviations: Not according to guidelines, but without clinical relevance, and 3) Major deviations: Clinical significant deviation. Categories 1) and 2) are clinical acceptable, whereas category 3) is clinical unacceptable. Results: The complete digital RT dataset was uploaded for all 504 patients and QA parameters were extracted. The results are shown in table 1. Not all patients contribute to the PRV data, since the PRV concept was introduced in the Danish clinics shortly after 2007. Furthermore, 13 patients (2.6%) were eliminated from the CTV QA due to challenges to extract dose summations (e.g. re-scans and primary/ boost dose plans) from the database. A total of 11 major deviations were recorded. Four major deviations in CTV1 dose coverage were due to clinical considerations of the tolerance dose to the spinal cord, thus compromising target dose. Five of the major deviations in total treatment time were related to comorbidities, such as alcohol- or cardiac related matters and hospitalization. The remaining two cases were due to tracheotomy procedures and subsequent re-scans, which delayed the RT course. Table 1: Summary of results from RT-QA of the DAHANCA protocol. Conclusions: RT dose plans in DAHANCA 19 adhere well to national clinical guidelines. A total of 11 major deviations were found in 504 patients. All majors were clinically well accounted for.

Purpose/Objective: Deformable registrations of medical images are becoming widely used for both radiotherapy optimization, but also for treatment response evaluation, e.g. defining relapses. However, the accuracy of deformable image registration (DIR) is rarely validated. The current study evaluates the accuracy of the open source deformable registration tool elastix when used for registration of different organ structures on planning CT and relapse CT scans of head and neck patients. Materials and Methods: Twenty patients treated with definitive IMRT for oral cavity, oropharynx and hypopharynx cancer in 2010-2012 were retrospectively and randomly included in the study. For each patient a planning CT and a diagnostic relapse CT scan were used (CT voxels were 3 mm in the cranio-caudal (CC) direction and 1 mm in the in-plane directions). One observer manually contoured 8 organs (spinal cord, mandible, right/left parotid and submandibular glands, thyroid gland and vertebrae C3-5) on planning CT (pCT), relapse CT (rCT) and re-delineated again on the planning CT (reCT). The contouring on the relapse CT was mapped to the planning CT using elastix (http://elastix.isi.uu.nl/). Spatial analysis of the difference in ROI delineation was performed by measuring the minimum distance between the two ROI's on each surface point of the original ROI. For each ROI the combined uncertainty of DIR and delineation was calculated as the standard deviation of the minimum surface distances. Organ type specific uncertainties were calculated as Root- Mean-Square (RMS) of the patient individual standard deviations. Re-delineation was used as a baseline for the obtainable uncertainty. Spearman's correlation between uncertainties of re-delineation and deformed delineation was performed to check whether delineation uncertainty influenced the outcome of the deformable results. Results: Surface plot of the spatial resolved deviation showed that the largest deviations where mainly in the CC direction (areas where the ROI surface normal primarily is in the CC direction) (left submandibular gland as an example, picture). RMS values for re-delineation and DIR are shown in table. A significant but low correlation exists between the ROI uncertainty of individual re-delineation and deformable contours (R=0.23, p=0.004). Thus a part of the deformable uncertainties are related to uncertainty of the manual ROI delineation. Significant correlations within single organs were not found. Conclusions: Deformable registration of head and neck CT images using elastix resulted in a combined delineation and deformation uncertainty of approximately twice the uncertainty related to the manual delineation performed on one CT. These uncertainties should be considered when using image deformations and registrations for clinical and research purposes.

Choice of rainfall-runoff algorithm is obviously a central aspect of urban drainage design. Although it is known that the size and imperviousness of the watershed have a bearing on the choice of algorithm, there is in Canada little evidence that any one algorithm is strongly preferred by most practitioners for application to a given design setting, and less evidence of any one algorithm being broadly specified in Canadian municipal regulations. If a given algorithm is chosen or specified, the reason for the choice is often unclear. The fact that the watershed in question does not yet exist (as an urbanised watershed) and that flow over impermeable surfaces and through sewers is more a question of hydraulics than of hydrology indicate that greater consistency in engineering practice should exist. No single commercial software package can execute all known algorithms. An overview of Canadian practice is presented, with reference to drainage design guidelines published by major municipalities in representative regions of the country. The main rainfall-runoff algorithms in use are listed, with brief comments on their respective hydrologic advantages and disadvantages. A \342\200\230best-practice\342\200\231 ranking of these algorithms is suggested, with qualifications. It is shown that there is little correspondence between the obvious advantages of some of the algorithms as compared to their prevalence of recommended use. Recommendations are made pertaining to standardization of procedures.