Mauro Cattaneo

An automatic contour propagation method to follow parotid gland deformation during head-and-neck cancer tomotherapy

We developed an efficient technique to auto-propagate parotid gland contours from planning kVCT to daily MVCT images of head-and-neck cancer patients treated with helical tomotherapy. The method deformed a 3D surface mesh constructed from manual kVCT contours by B-spline free-form deformation to generate optimal and smooth contours. Deformation was calculated by elastic image registration between kVCT and MVCT images. Data from ten head-and-neck cancer patients were considered and manual contours by three observers were included in both kVCT and MVCT images. A preliminary inter-observer variability analysis demonstrated the importance of contour propagation in tomotherapy application: a high variability was reported in MVCT parotid volume estimation (p = 0.0176, ANOVA test) and a larger uncertainty of MVCT contouring compared with kVCT was demonstrated by DICE and volume variability indices (Wilcoxon signed rank test, p < 10(-4) for both indices). The performance analysis of our method showed no significant differences between automatic and manual contours in terms of volumes (p > 0.05, in a multiple comparison Tukey test), center-of-mass distances (p = 0.3043, ANOVA test), DICE values (p = 0.1672, Wilcoxon signed rank test) and average and maximum symmetric distances (p = 0.2043, p = 0.8228 Wilcoxon signed rank tests). Results suggested that our contour propagation method could successfully substitute human contouring on MVCT images.

Adenoid cystic carcinoma of trachea treated with adjuvant hypofractionated tomotherapy. Case report and literature review

Adenoid cystic carcinoma, also called cylindroma, is the second most common histological type of tracheal malignancy but represents 1% of all respiratory tract cancers. We report a case of a 59-year-old patient submitted to an incomplete resection of the trachea and subsequently treated with adjuvant tomotherapy. There have been no reports in the literature regarding intensity-modulated radiation therapy with linac or tomotherapy systems in adenoid cystic carcinoma of the trachea. The present clinical case demonstrates the feasibility of adjuvant intensity-modulated radiation therapy techniques for optimizing the dose coverage of the tumor bed while sparing surrounding normal tissues. A dosimetric comparison between the tomotherapy plan and a 3-dimensional conformal radiotherapy plan is also reported. We demonstrate that tomotherapy permits an increase in the dose per fraction without important acute adverse effects. At 24 months’ follow-up, our patient shows no evidence of disease with negative histological findings.

Moderately Hypofractionated Helical IMRT, FDG–PET/CT-guided, for Progressive Malignant Pleural Mesothelioma in Patients With Intact Lungs

Introduction: The objective of this study was to present the outcomes of moderately hypofractionated helical intensity‐modulated radiation therapy (HT) with/without simultaneous integrated boost (SIB) on fluorodeoxyglucose‐positron emission tomography (FDG‐PET) positive areas (gross tumor volume [GTV]‐PET) for patients with progressive malignant pleural mesothelioma (MPM) after previous treatments. Methods and Materials: From May 2006 to April 2014, 51 patients with a median age of 68.8 years (range, 38.6‐82 years) were treated. There were 41 men and 10 women; 43 epithelioid MPM and 8 sarcomatoid, involving the left pleura in 25 patients and the right pleura in 26 patients. The initial stage was: I, 11 patients; II, 14 patients; III, 17 patients; and IV, 9 patients. Chemotherapy was prescribed for 46 patients, for 6 cycles (range, 0‐18 cycles). Eighteen patients had pleurectomy/decortication, and 33 had talc pleurodesis. FDG‐PET was used for target identification. A median dose of 56 Gy/25 fractions was prescribed to the involved pleura, and SIB to 62.5 Gy to GTV‐PET was added in 38 patients. Results: The median survival from diagnosis was 25.8 months (range, 8.4‐99.0 months). One patient, treated with SIB, was alive at the October 2017 follow‐up. Two cases of grade 5 radiation pneumonitis were registered. A GTV‐PET ≤ 205 cc was predictive of late ≥ grade 2 lung toxicity, but also of better survival in stage III and IV disease: 5.9 versus 11.7 months (P = .04). A GTV‐PET ≥ 473 cc was predictive of early death (P = .001). Conclusions: Moderately hypofractionated, FDG‐PET guided salvage HT in patients with progressive MPM after previous treatments showed acceptable toxicity and outcome results similar to adjuvant radiotherapy after pleurectomy/decortication, suggesting that the delay of radiotherapy is not detrimental to survival, and has the associated benefit of postponing inherent toxicity.

Second Tumor Induction Risk in IMRT for Prostate Cancer: An Unbalanced Comparison Between Surgery and Radiotherapy?

AbstractThe aim of this study was to evaluate the risk of second tumor induction for prostate patients treated with volumetric modulated arc therapy in age classes 50–70. Based on both age-dependent models and doses to critical organs, the risk of second tumor induction was evaluated simulating the small field (prostate and seminal vesicles) and large field (whole pelvis) for Helical Tomotherapy and Rapid Arc. The doses to the organs closest to the treatment volume were derived from treatment planning system data. Whereas, due to the lack of calculation algorithms where leakage and internal radiation scattering are unreliable at a large distance from target, the doses to the organs outside the treatment volume were measured in an anthropomorphic phantom. Doses from Image Guided Radiotherapy (IGRT) were also assessed on phantom measurements. The Lifetime Attributable Risk (LAR) for second tumor induction increases from 2.2 to 13.7% as irradiated volume increases and age decreases. IGRT could add a non-negligible factor to the risk when daily set-up verification with high-resolution modality is included. As prostate cancer is detected earlier, the probability of an increase in early stage patients rises, and life expectancy thus increases. Radiotherapy has improved its capability in the tailoring of the dose around the target at the cost of a greater dose to surrounding organs, thus increasing the risk of second tumor induction, especially for those patients expected to survive 15 y or more.