Purpose: The integration of CT and multiparametric MRI (mpMRI) is a challenging task in high-precision radiotherapy for prostate cancer. A simple methodology for multimodal deformable image registration (DIR) of prostate cancer patients is presented. Methods: CT and mpMRI of 10 patients were considered. Organs at risk and prostate were contoured on both scans. The dominant intraprostatic lesion was additionally delineated on MRI. After a preliminary rigid image registration, the voxel intensity of all the segmented structures in both scans except the prostate was increased by a specific amount (a constant additional value, A), in order to enhance the contrast of the main organs influencing its position and shape. 70 couples of scans were obtained by varying A from 0 to 800 and they were subsequently non-rigidly registered. Quantities derived from image analysis and contour statistics were considered for the tuning of the best performing A. Results: A = 200 resulted the minimum enhancement value required to obtain statistically significant superior registration results. Mean centre of mass distance between corresponding structures decreases from 7.4 mm in rigid registration to 5.3 mm in DIR without enhancement (DIR-0) and to 2.7 mm in DIR with A = 200 (DIR-200). Mean contour distance was 2.5, 1.9 and 0.67 mm in rigid registration, DIR-0 and DIR-200, respectively. In DIR-200 mean contours overlap increases of +13 and +24% with respect to DIR-0 and rigid registration, respectively. Conclusion: Contour propagation according to the vector field resulting from DIR-200 allows the delineation of dominant intraprostatic lesion on CT scan and its use for high-precision radiotherapy treatment planning. Advances in knowledge: We investigated the application of a B-spline, mutual information-based multimodal DIR coupled with a simple, patient-unspecific but efficient contrast enhancement procedure in the pelvic body area, thus obtaining a robust and accurate methodology to transfer the functional information deriving from mpMRI onto a planning CT reference volume.

Introduction Of the different treatments for early prostate cancer, hypofractionated external-beam radiotherapy is one of the most interesting and studied options. Methods The main objective of this phase II clinical study is to evaluate the feasibility, in terms of the incidence of acute side effects, of a new ultra-hypofractionated scheme for low- or intermediate-risk prostate cancer patients treated with the latest imaging and radiotherapy technology, allowing dose escalation to the dominant intraprostatic lesion identified by multiparametric magnetic resonance imaging. Secondary endpoints of the study are the evaluation of the long-term tolerability of the treatment in terms of late side effects, quality of life, and efficacy (oncological outcome). Results The study is ongoing, and we expect to complete recruitment by the end of 2016. Conclusions Like in previous studies, we expect ultra-hypofractionated radiation treatment for prostate cancer to be well tolerated and effective. Trial registration ClinicalTrials.gov identifier: NCT01913717.

Objective: To report preliminary results of a cutting edge extreme hypofractionated treatment with concomitant boost to the dominant lesion for patients with early stage prostate cancer (PCa). Methods: AIRC-IG-13218 is a prospective phase II trial started in June 2015. Patients with low and intermediate risk PCa who met the inclusion criteria underwent extreme hypofractionated radiotherapy to the prostate (36.25 Gy in 5 fractions) and a simultaneous integrated boost to the dominant intraprostatic lesion (DIL) to 37.5 Gy. The DIL was identified by a multiparamentric magnetic resonance imaging (mpMRI) co-registered with planning CT. Toxicity was assessed according to CTCAE v4.0 and RTOG/EORTC criteria. The preliminary evaluation of the first 13 patients was required to confirm the feasibility of the treatment before completing the enrollment of 65 patients. Results: The first 13 patients completed the treatment between June 2015 and February 2016. With a median clinical follow-up of 17 months (range 11–26),...

The superior diagnostic accuracy of [68Ga]Ga-prostate-specific membrane antigen-11 (PSMA) ([68Ga]Ga-PSMA-11) compared to [18F]F-Fluorocholine Positron Emission Tomography/Computed Tomography (PET/CT) in Prostate Cancer (PCa) is established. However, it is currently unclear if the added diagnostic accuracy actually translates into improved clinical outcomes in oligometastatic PCa patients treated with [68Ga]Ga-PSMA-11 PET-guided metastasis-directed therapy (MDT). The present study aimed to assess the impact of these two imaging techniques on Progression-Free Survival (PFS) in a real-world sample of oligometastatic PCa patients submitted to PET-guided MDT. Thirty-seven oligometastatic PCa patients treated with PET-guided MDT were retrospectively enrolled. MDT was guided by [18F]F-Fluorocholine PET/CT in eleven patients and by [68Ga]Ga-PSMA-11 PET/CT in twenty-six. Progression was defined as biochemical recurrence (BR), radiological progression at subsequent PET/CT imaging, clinical progression, androgen deprivation therapy initiation, or death. Clinical and imaging parameters were assessed as predictors of PFS. [18F]F-Fluorocholine PET-guided MDT was associated with significantly lower PFS compared to the [68Ga]Ga-PSMA-11 group (median PFS, mPFS 15.47 months, 95% CI: 4.13–38.00 vs. 40.93 months, 95% CI: 40.93–40.93, respectively; p < 0.05). Coherently, the radiotracer used for PET-guided MDT resulted in predictive PFS at the univariate analysis, as well as the castration-resistant status at the time of MDT and the PSA nadir after MDT. However, in the multivariate analysis, castration resistance and PSA nadir after MDT remained the sole independent predictors of PFS. In conclusion, in the present proof-of-concept study, [68Ga]Ga-PSMA-11 provided higher PFS rates than [18F]F-Fluorocholine imaging in oligometastatic PCa patients receiving PET-guided MDT. Although preliminary, this finding suggests that enlarging the “tip of the iceberg”, by detecting a major proportion of the submerged disease thanks to next-generation imaging may favourably impact the oncological outcome of oligometastatic PCa treated with MDT.

Purpose: The use of helical tomotherapy (HT) for craniospinal irradiation (CSI) in pediatric patients remains an issue of discussion. In this study, we evaluated the integral dose (ID) to organs at risk (OARs) and to the whole body delivered with conventional 3-dimensional conformal radiotherapy (3D-CRT) and HT for pediatric patients and made a comparison according to different whole body volumes. Methods: We selected 10 pediatric patients with different body volumes and of different ages undergoing CSI. Plans for 3D-CRT and HT were developed for each patient. The ID to OARs and to the whole body were compared and statistical analyses were performed to determine differences. Results: We noticed that variations of ID depend on the different anatomical location of the organs relatively to the target, with lower ID to OARs opposed to the target and increased ID to lateral organs: ID tomotherapy/3D-CRT ratio was higher in lungs, kidneys, and mammary region, while it was lower in heart, liver, thyroid, and esophagus. The ID of the body increased with large volumes both in HT and in 3D-CRT plans, but in tomotherapy plans ID increased significantly more with large volumes than with small ones. Conclusions: While there are no differences in using tomotherapy or 3D-CRT with small body volumes, we found a difference with large volumes (≥20,000 mL vs ≤20,000 mL). Therefore, for very small patients, the use of intensity-modulated radiotherapy provided with tomotherapy to reduce the dose to OARs can be reconsidered.