Safety and Tolerability of Online Adaptive High-Field Magnetic Resonance-Guided Radiotherapy.

Importance: In 2018, the first online adaptive magnetic resonance (MR)-guided radiotherapy (MRgRT) system using a 1.5-T MR-equipped linear accelerator (1.5-T MR-Linac) was clinically introduced.

Patterns of Care, Tolerability, and Safety of the First Cohort of Patients Treated on a Novel High-Field MR-Linac Within the MOMENTUM Study: Initial Results From a Prospective Multi-Institutional Registry.

Purpose: High-field magnetic resonance-linear accelerators (MR-Linacs), linear accelerators combined with a diagnostic magnetic resonance imaging (MRI) scanner and online adaptive workflow, potentially give rise to novel online anatomic and response adaptive radiation therapy paradigms. The first high-field (1.5T) MR-Linac received regulatory approval in late 2018, and little is known about clinical use, patient tolerability of daily high-field MRI, and toxicity of treatments.

The MOMENTUM Study: An International Registry for the Evidence-Based Introduction of MR-Guided Adaptive Therapy.

MR-guided Radiation Therapy (MRgRT) allows for high-precision radiotherapy under real-time MR visualization. This enables margin reduction and subsequent dose escalation which may lead to higher tumor control and less toxicity. The Unity MR-linac (Elekta AB, Stockholm, Sweden) integrates a linear accelerator with a 1.

Risk of benign meningioma after childhood cancer in the DCOG-LATER cohort: contributions of radiation dose, exposed cranial volume, and age.

Background: Pediatric cranial radiotherapy (CrRT) markedly increases risk of meningiomas. We studied meningioma risk factors with emphasis on independent and joint effects of CrRT dose, exposed cranial volume, exposure age, and chemotherapy.

Methods: The Dutch Cancer Oncology Group-Long-Term Effects after Childhood Cancer (DCOG-LATER) cohort includes 5-year childhood cancer survivors (CCSs) whose cancers were diagnosed in 1963-2001.

Post-lumpectomy CT-guided tumor bed delineation for breast boost and partial breast irradiation: Can additional pre- and postoperative imaging reduce interobserver variability?

For breast boost radiotherapy or accelerated partial breast irradiation, the tumor bed (TB) is delineated by the radiation oncologist on a planning computed tomography (CT) scan. The aim of the present study was to investigate whether the interobserver variability (IOV) of the TB delineation is reduced by providing the radiation oncologist with additional magnetic resonance imaging (MRI) or CT scans. A total of 14 T1-T2 breast cancer patients underwent a standard planning CT in the supine treatment position following lumpectomy, as well as additional pre- and postoperative imaging in the same position.

Intra-fraction uncertainties of MRI guided brachytherapy in patients with cervical cancer.

Dosimetric intra-fraction uncertainties in MRI-guided brachytherapy were analysed for HR-CTV and OARs. While dose differences were generally small, individual outliers occurred. In contrast to HDR, patients treated with PDR show increased mean rectal dose over time.

MRI and CT imaging for preoperative target volume delineation in breast-conserving therapy.

Background: Accurate tumor bed delineation after breast-conserving surgery is important. However, consistency among observers on standard postoperative radiotherapy planning CT is low and volumes can be large due to seroma formation. A preoperative delineation of the tumor might be more consistent.

Clinical outcome and dosimetric parameters of chemo-radiation including MRI guided adaptive brachytherapy with tandem-ovoid applicators for cervical cancer patients: a single institution experience.

Purpose: To evaluate dosimetric parameters and clinical outcome for cervical cancer patients treated with chemo-radiation and MR-image guided adaptive brachytherapy (MR-IGABT) using tandem-ovoid applicators for intracavitary or combined intracavitary/interstitial approaches.

Method: This retrospective analysis includes 46 patients treated between 2006 and 2008. Dose-volume parameters D90 HR-CTV (high-risk clinical target volume) and D(2cc) OARs (organs at risk) were determined and converted into biologically equivalent doses in 2 Gy fractions (EQD2).

Clinical use of the Utrecht applicator for combined intracavitary/interstitial brachytherapy treatment in locally advanced cervical cancer.

Purpose: The aims of this study were to investigate the benefit of the Utrecht interstitial CT/MR applicator for combined intracavitary/interstitial (IC/IS) approach, using magnetic resonance imaging-guided brachytherapy, over the intracavitary approach alone in patients with locally advanced cervical cancer and to analyze the clinical use of needles.

Methods And Materials: This study includes the first 20 patients treated with the new applicator. Brachytherapy consisted of two pulsed dose rate applications, and the second application was performed with the IC/IS approach.

Internal motion of the vagina after hysterectomy for gynaecological cancer.

Background And Purpose: The purpose of this study was to investigate position changes of the vagina after hysterectomy for early stage cervical or endometrial cancer and their impact on CTV-PTV margins. We also studied their correlation with surrounding organ filling.

Materials And Methods: Fifteen patients underwent T2-weighted MR scans before and weekly during the course of their EBRT.

MRI-guided treatment-planning optimisation in intracavitary or combined intracavitary/interstitial PDR brachytherapy using tandem ovoid applicators in locally advanced cervical cancer.

Purpose: To study the impact of MRI-guided treatment planning on dose/volume parameters in pulsed dose rate (PDR) brachytherapy (BT) for cervical cancer. Additionally, we investigated the potential benefit of an intracavitary/interstitial (IC/IS) modification of the classical tandem ovoid applicator.

Material And Methods: For 24 patients we compared Standard PDR BT plans, Scaled Standard plans and MRI-guided Optimised plans.

Changes in excision cavity volume: prediction of the reduction in absolute volume during breast irradiation.

Purpose: The aim of this study was to determine the changes in the excision cavity volume due to the resolution of the surgical effects during the whole breast treatment.

Materials And Methods: Seventy-seven patients with early-stage (T1-2 N0) breast cancer treated with breast-conserving therapy were included for this study. All patients underwent a standard planning computed tomography (CT) scan before irradiation treatment.

Motion and deformation of the target volumes during IMRT for cervical cancer: what margins do we need?

Background And Purpose: For cervical cancer patients the CTV consists of multiple structures, exhibiting complex inter-fraction changes. The purpose of this study is to use weekly MR imaging to derive PTV margins that accommodate these changes.

Materials And Methods: Twenty patients with cervical cancer underwent a T2-weighted MRI exam before and weekly during IMRT.

Interobserver variability of clinical target volume delineation of glandular breast tissue and of boost volume in tangential breast irradiation.

Background And Purpose: To determine the interobserver variability of clinical target volume delineation of glandular breast tissue and of boost volume in tangential breast irradiation.

Patients And Methods: Eighteen consecutive patients with left sided breast cancer treated by breast conserving surgery agreed to participate in our study. Volumes of the glandular breast tissue (CTV breast) and of the boost (CTV boost) were delineated by five observers.

Prevention of pterygium recurrence by postoperative single-dose beta-irradiation: a prospective randomized clinical double-blind trial.

Purpose: To affirm the effectiveness and complication rate of postoperative single-dose beta-irradiation (RT) with (90)Sr in the case of primary pterygium in a clinical trial. Pterygium is a benign disease of the supporting orbital tissue that can cause impairment of visual function. Depending on the technique used for surgery, recurrence is described in up to 70% of cases-a reason to combine the initial treatment with radiotherapy or chemotherapy.