Dose mimicking based strategies for online adaptive proton therapy of head and neck cancer.

Objective.To compare a not adapted (NA) robust planning strategy with three fully automated online adaptive proton therapy (OAPT) workflows based on the same optimization method: dose mimicking (DM). The added clinical value and limitations of the OAPT methods are investigated for head and neck cancer (HNC) patients.Approach.The three OAPT strategies aimed at compensating for inter-fractional anatomical changes by mimiking different dose distributions on corrected cone beam CT images (corrCBCTs). Order by complexity, the OAPTs were: (1) online adaptive dose restoration (OADR) where the approved clinical dose on the planning-CT (pCT) was mimicked, (2) online adaptation using DM of the deformed clinical dose from the pCT to corrCBCTs (OADEF), and (3) online adaptation applying DM to a predicted dose on corrCBCTs (OAML). Adaptation was only applied in fractions where the target coverage criteria were not met (D98% < 95% of the prescribed dose). For 10 HNC patients, the accumulated dose distributions over the 35 fractions were calculated for NA, OADR, OADEF, and OAML.Main results.Higher target coverage was observed for all OAPT strategies compared to no adaptation. OADEF and OAML outperformed both NA and OADR and were comparable in terms of target coverage to initial clinical plans. However, only OAML provided comparable NTCP values to those from the clinical dose without statistically significant differences. When the NA initial plan was evaluated on corrCBCTs, 51% of fractions needed adaptation. The adaptation rate decreased significantly to 25% when the last adapted plan with OADR was selected for delivery, to 16% with OADEF, and to 21% with OAML. The reduction was even greater when the best plan among previously generated adapted plans (instead of the last one) was selected.Significance. The implemented OAPT strategies provided superior target coverage compared to no adaptation, higher OAR sparing, and fewer required adaptations.

Health-related quality of life and cognitive failures in patients with lower-grade gliomas treated with radiotherapy.

PURPOSE: Patients with lower grade (grade 2 and 3) glioma (LGG) frequently experience prolonged clinical course after multimodal therapy (including surgery, radiotherapy (RT), and chemotherapy). There is therefore significant concern about the potential long-term impact of the disease and treatments on quality of life (QOL) and cognitive functioning. In this context, we evaluated health related QOL and cognitive failures in LGG patients previously treated in our RT department. PATIENTS AND METHODS: Adult LGG patients previously treated with RT were prospectively included. Patients were evaluated based on standardized questionnaires [i.e., EORTC QLQ-C30, EORTC QLQ-BN20, and cognitive failures questionnaire (CFQ)]. RESULTS: Forty-eight patients were included. Median time elapsed since the end of RT was 59.5 months (range: 4-297). Based on EORTC QLQ-C30 and QLQ-BN20, the most prevalent HRQOL issues were impaired cognitive functioning (50% of the patients), impaired emotional functioning (47.9%), financial difficulties (43.7%), fatigue (43.7%), future uncertainty (39.6%), and impaired physical functioning (35.4%). Based on the CFQ, 35.4% of the patients showed increased tendency to cognitive failures. CONCLUSION: Patients with LGG frequently experience impairments in HRQOL and cognitive failures after treatment (including RT). Further efforts are therefore warranted to improve the QOL and cognitive outcome of these patients.

Metabolic imaging in non-small-cell lung cancer radiotherapy.

Metabolic imaging by positrons emission tomography (PET) offers new perspectives in the field of non-small-cell lung cancer radiation therapy. First, it can be used to refine the way nodal and primary tumour target volumes are selected and delineated, in better agreement with the underlying tumour reality. In addition, the non-invasive spatiotemporal mapping of the tumour biology and the organs at risk function might be further used to steer radiation dose distribution. Delivering higher dose to low responsive tumour area, in a way that better preserves the normal tissue function, should thus reconcile the tumour radiobiological imperatives (maximising tumour local control) with dose related to the treatment safety (minimising late toxicity). By predicting response early in the course of radiation therapy, PET may also participate to better select patients who are believed to benefit most from treatment intensification. Altogether, these technological advances open avenues to in-depth modify the way the treatment plan is designed and the dose is delivered, in better accordance with the radiobiology of individual solid cancers and normal tissues.