MR-Guided Adaptive Radiotherapy in Localized Prostate Cancer.

MR-guided radiotherapy (MRgRT) is novel treatment modality in Radiation Oncology that could allow a higher precision and tolerability of Radiation Treatments. This modality is possible due to dedicated systems consisting of a MR scanner mounted on a conventional linac and software that permit daily online treatment plan adaptation. Prostate cancer (PC) is one of the most common malignancies in RO clinical practice and currently under investigation with this new technology.

Validation of a Monte Carlo-based dose calculation engine including the 1.5 T magnetic field for independent dose-check in MRgRT.

Purpose: Adaptive MRgRT by 1.5 T MR-linac requires independent verification of the plan-of-the-day by the primary TPS (Monaco) (M). Here we validated a Monte Carlo-based dose-check including the magnetostatic field, SciMoCa (S).

1.5T MR-Guided Daily-Adaptive SBRT for Prostate Cancer: Preliminary Report of Toxicity and Quality of Life of the First 100 Patients.

The present study reports the preliminary outcomes in terms of adverse events and quality of life in the first 100 patients treated with 1.5T MR-guided daily-adaptive stereotactic body radiotherapy for prostate cancer. From October 2019 to December 2020, 100 patients, enrolled in a prospective study, received MR-guided SBRT for prostate cancer.

1.5T MR-Guided Daily Adaptive Stereotactic Body Radiotherapy for Prostate Re-Irradiation: A Preliminary Report of Toxicity and Clinical Outcomes.

Background: Prostate re-irradiation is an attractive treatment option in the case of local relapse after previous radiotherapy, either in the definitive or in the post-operative setting. In this scenario, the introduction of MR-linacs may represent a helpful tool to improve the accuracy and precision of the treatment.

Methods: This study reports the preliminary data of a cohort of 22 patients treated with 1.

Automated Planning for Prostate Stereotactic Body Radiation Therapy on the 1.5 T MR-Linac.

Purpose: Adaptive stereotactic body radiation therapy (SBRT) for prostate cancer (PC) by the 1.5 T MR-linac currently requires online planning by an expert user. A fully automated and user-independent solution to adaptive planning (mCycle) of PC-SBRT was compared with user's plans for the 1.

Reduction of inter-observer differences in the delineation of the target in spinal metastases SBRT using an automatic contouring dedicated system.

Background: Approximately one third of cancer patients will develop spinal metastases, that can be associated with back pain, neurological symptoms and deterioration in performance status. Stereotactic radiosurgery (SRS) and stereotactic body radiotherapy (SBRT) have been offered in clinical practice mainly for the management of oligometastatic and oligoprogressive patients, allowing the prescription of high total dose delivered in one or few sessions to small target volumes, minimizing the dose exposure of normal tissues. Due to the high delivered doses and the proximity of critical organs at risk (OAR) such as the spinal cord, the correct definition of the treatment volume becomes even more important in SBRT treatment, thus making it necessary to standardize the method of target definition and contouring, through the adoption of specific guidelines and specific automatic contouring tools.

Mammary Chain Irradiation in Left-Sided Breast Cancer: Can We Reduce the Risk of Secondary Cancer and Ischaemic Heart Disease with Modern Intensity-Modulated Radiotherapy Techniques?

Introduction: The aim of the present study was to estimate the impact of the addition of internal mammary chain (IMC) irradiation in node-positive left-sided breast cancer (BC) patients undergoing regional nodal irradiation (RNI) and comparatively evaluate excess relative and absolute risks of radiation-induced lung cancer/BC and ischaemic heart disease for intensity-modulated radiotherapy (IMRT) versus 3D conformal radiotherapy (3D-CRT).

Methods: Four treatment plans were created (3D-CRT and IMRT -/+ IMC) for each of the 10 evaluated patients, and estimates of excess relative risk (ERR) and 10-year excess absolute risk (EAR) were calculated for radiation-induced lung cancer/BC and coronary events using linear, linear-exponential and plateau models.

Results: The addition of IMC irradiation to RNI significantly increased the dose exposure of the heart, lung and contralateral breast using both techniques, increasing ERR for secondary lung cancer (58 vs.

Impact of hydrogel peri-rectal spacer insertion on seminal vesicles intrafraction motion during 1.5 T-MRI-guided adaptive stereotactic body radiotherapy for localized prostate cancer.

Objectives: MR-guided daily-adaptive radiotherapy is improving the accuracy in the planning and delivery phases of the treatment. Rectal hydrogel-spacer may help in mitigating organ motion, but few data are currently available.

Methods: We aimed to assess any potential impact of the device on seminal vesicles motion by measuring translational and rotational shifts between the pre- and post-treatment MRI scans of a total of 50 fractions in the first 10 patients who underwent MR-guided prostate SBRT (35 Gy/5 fx).

Mitigation on bowel loops daily variations by 1.5-T MR-guided daily-adaptive SBRT for abdomino-pelvic lymph-nodal oligometastases.

Purpose: We report preliminary dosimetric data concerning the use of 1.5-T MR-guided daily-adaptive radiotherapy for abdomino-pelvic lymph-nodal oligometastases. We aimed to assess the impact of this technology on mitigating daily variations for both target coverage and organs-at-risk (OARs) sparing.

Stereotactic body radiotherapy for oligometastatic castration sensitive prostate cancer using 1.5 T MRI-Linac: preliminary data on feasibility and acute patient-reported outcomes.

Objectives: To report preliminary data on feasibility and patient-reported outcomes following PSMA-PET/CT guided SBRT by means of 1.5 T MRI-Linac.

Methods And Materials: Between October 2019 and April 2020, twenty consecutive castration sensitive oligorecurrent prostate cancer patients were enrolled in an ethical committee approved prospective observational study (Protocol n.

Long-term disease outcome and volume-based decision strategy in a large cohort of multiple brain metastases treated with a mono-isocentric linac-based Stereotactic Radiosurgery technique.

Purpose: Radiosurgery (SRS) is an effective treatment option for brain metastases (BMs). Long-term results of the first worldwide experience with a mono-isocentric, non-coplanar, linac-based stereotactic technique in the treatment of multiple BMs are reported.

Methods: patients with multiple BMs, life expectancy > 3 months, and good performance status (≤ 2) were treated with simultaneous SRS with volumetric modulated arc technique.

Rectal spacer hydrogel in 1.5T MR-guided and daily adapted SBRT for prostate cancer: dosimetric analysis and preliminary patient-reported outcomes.

Objective: The main aim of the current analysis was to explore the hypothetical advantages using rectal spacer during 1.5T MR-guided and daily adapted prostate cancer stereotactic body radiotherapy (SBRT) compared to a no-rectal spacer hydrogel cohort of patients.

Methods: The SBRT-protocol consisted of a 35 Gy schedule delivered in 5 fractions.

Adaptive SBRT by 1.5 T MR-linac for prostate cancer: On the accuracy of dose delivery in view of the prolonged session time.

Purpose: Adaptive Stereotactic Body Radiotherapy (SBRT) of prostate cancer (PC) by online 1.5 T MRi-guidance prolongs session-time, due to contouring and planning tasks, thus increasing the risk of prostate motion. Hence, the interest to verify the adequacy of the delivered dose.

Daily dosimetric variation between image-guided volumetric modulated arc radiotherapy and MR-guided daily adaptive radiotherapy for prostate cancer stereotactic body radiotherapy.

Aim: To evaluate differences between MR-guided daily-adaptive RT (MRgRT) and image-guided RT (IGRT) with or without fiducial markers in prostate cancer (PCa) stereotactic body radiotherapy (SBRT) in terms of dose distribution on critical structures.

Material And Methods: Two hundred treatment sessions in 40 patients affected by low and intermediate PCa were evaluated. The prescribed dose was 35 Gy in 5 fractions delivered on alternate days.

Feasibility and safety of 1.5 T MR-guided and daily adapted abdominal-pelvic SBRT for elderly cancer patients: geriatric assessment tools and preliminary patient-reported outcomes.

Background: We present preliminary data of the first older cancer patients treated with Hybrid Linac for stereotactic body radiotherapy (SBRT) consisting of 1.5 T MRI-guided and daily-adapted treatment. The aim was to assess feasibility, safety and the role of G8 and Charlson Comorbidity Index (CCI) questionnaires in predicting patients' QoL, evaluated by patient-reported outcome measures (PROMs).

1.5 T MR-guided and daily adapted SBRT for prostate cancer: feasibility, preliminary clinical tolerability, quality of life and patient-reported outcomes during treatment.

Background: Unity Elekta is a unique magnetic resonance (MR)-linac that conjugates a 1.5 Tesla MR unit with a 7 MV flattening filter free accelerator.A prospective observational study for the clinical use of Elekta Unity is currently ongoing in our department.

Linac-based radiosurgery for multiple brain metastases: Comparison between two mono-isocenter techniques with multiple non-coplanar arcs.

Background And Purpose: Three mono-isocenter techniques with multiple non-coplanar arcs are nowadays clinically available for linac-based stereotactic radiosurgery (SRS) of multiple brain metastases (BM): HyperArc (HA), Multiple Brain Mets (MBM), and Monaco-HDRS. Two of them, HA and MBM, are here compared in terms of plan-quality, and dosimetric consistency between planning and delivering.

Materials And Methods: For 20 patients with multiple BM (2-10), treated by mono-isocenter volumetric modulated arc therapy (VMAT) HA plans, mono-isocenter MBM dynamic conformal arc plans were generated.

Intensity-modulated radiotherapy and hypofractionated volumetric modulated arc therapy for elderly patients with breast cancer: comparison of acute and late toxicities.

Purpose: To evaluate the differences between conventional fractionated intensity-modulated radiotherapy (IMRT) and hypofractionated (HypoRT) volumetric modulated arc therapy (VMAT) in elderly women affected by early-stage breast cancer (BC) in terms of RT-related acute/late side effect.

Materials And Methods: Between October 2011 and July 2015, 80 consecutive elderly BC patients were treated with IMRT for 5 weeks (40 patients) or HypoRT-VMAT for 3 weeks (40 patients). Inclusion criteria were: age ≥ 70 years, early BC (pT1-2 pN0-1), no prior neoadjuvant chemotherapy and non-metastatic disease.

Linac-based VMAT radiosurgery for multiple brain lesions: comparison between a conventional multi-isocenter approach and a new dedicated mono-isocenter technique.

Background: Linac-based stereotactic radiosurgery or fractionated stereotactic radiotherapy (SRS/FSRT) of multiple brain lesions using volumetric modulated arc therapy (VMAT) is typically performed by a multiple-isocenter approach, i.e. one isocenter per lesion, which is time-demanding for the need of independent setup verifications of each isocenter.

Moderate Hypofractionated Postprostatectomy Volumetric Modulated Arc Therapy With Daily Image Guidance (VMAT-IGRT): A Mono-institutional Report on Feasibility and Acute Toxicity.

Introduction: The aim of this study was to evaluate the acute toxicity profiles of a moderate hypofractionated regimen with volumetric modulated arc therapy (VMAT) in patients with prostate cancer (PC) who underwent radical prostatectomy.

Material And Methods: From December 2012 to February 2016, 125 patients, previously having undergone radical prostatectomy, received adjuvant (64 patients) or salvage (61 patients) radiotherapy (RT) inside an institutional protocol of moderate hypofractionation schedule using the VMAT technique (Varian RapidArc, Palo Alto, CA). Eligible patients were < 85 years old, with an Eastern Cooperative Oncology Group performance status of 0 to 2, histologically proven adenocarcinoma of the prostate without distant metastases, and pathologic stage pT2-4 N0-1, with at least 1 of the following risk factors: capsular perforation, positive surgical margins, seminal vesicle invasion, and/or postoperative prostate-specific antigen > 0.

Synchronous bilateral breast cancer irradiation: clinical and dosimetrical issues using volumetric modulated arc therapy and simultaneous integrated boost.

Objectives: The aim of the present retrospective analysis was to evaluate dosimetric parameters, feasibility and outcome for Synchronous Bilateral Breast Cancer (SBBC) patients treated with adjuvant radiotherapy (RT) by Volumetric Modulated Arc Therapy (VMAT).

Methods: From September 2011 to April 2016, 1100 Breast Cancer (BC) patients were referred to our institution to receive adjuvant breast RT, and those with SBBC were selected for the present analysis. A total of 16 patients were identified.

Optimal dose and fraction number in SBRT of lung tumours: A radiobiological analysis.

The efficacy of Stereotactic Body Radiation Therapy (SBRT) in early-stage non-small cell lung cancer for severely hypofractionated schedules is clinically proven. Tumour control probability (TCP) modelling might further optimize prescription dose and number of treatment fractions (n). To this end, we will discuss the following controversial questions.

Three-dimensional conformal versus intensity modulated radiotherapy in breast cancer treatment: is necessary a medical reversal?

Objectives: Aim of the present study is to compare three-dimensional conformal RT (3D-CRT) and 4-fields intensity modulated radiation therapy (4f-IMRT) treatment plans, in terms of target dose coverage, integral dose and dose to Organs at risk (OARs) in early breast cancer (BC).

Methods: Twenty consecutive BC patients, after lumpectomy, were selected for the present analysis. A total dose of 50 Gy and a simultaneous dose of 60 Gy in 25 fractions was prescribed to Planning Target Volume of the whole breast (PTV) and of the surgical bed, respectively.

Technical Note: Correction for intra-chamber dose gradients in reference dosimetry of flattening-filter-free MV photon beams.

Purpose: To estimate and correct for the volume averaging effect which results from the intra-chamber dose gradients when a Farmer ionization chamber (IC) is used for reference dosimetry in flattening-filter-free (FFF) MV photon beams.

Methods: An intra-chamber dose gradients correction factor (kicdg) to the charge reading of a Farmer IC is estimated by comparison to a small volume IC (∼0.1 cm(3)), in the FFF beams of a TrueBeam™ (Varian, Inc.

Applying radiobiological plan ranking methodology to VMAT prostate SBRT.

The impact of a rectal spacer and an increased near maximum target dose in VMAT prostate SBRT is studied. For a group of 11 patients (35Gy-in-five-fractions VMAT prostate SBRT) a set of 4 plans were generated, namely two VMAT plans, with D2%⩽37.5Gy (Hom) and with D2%⩽40.