Stefan Zijlema

Netherlands Cancer Institute · Department of Radiotherapy

Immobilization masks are used to prevent patient movement during head and neck (H&N) radiotherapy. Motion restriction is beneficial both during treatment, as well as in the pre-treatment simulation phase, where MRI is often used for target definition. However, the shape and size of the immobilization masks hinder the use of regular, close-fitting M...

The simultaneous use of positron emission tomography (PET) and magnetic resonance imaging (MRI) requires attenuation correction (AC) of photon-attenuating objects, such as MRI receive arrays. However, AC of flexible, on-body arrays is complex and therefore often omitted. This can lead to significant, spatially varying, PET signal losses when conven...

High impedance coils (HICs) are suitable as a building block of receive arrays for MRI-guided radiotherapy (MRIgRT) as these do not require radiation-attenuating capacitors and dense support materials. Recently, we proved the feasibility of using HICs to create a radiation transparent (i.e., radiolucent) window. In this work, we constructed a fully...

Motion is problematic during radiotherapy as it could lead to potential underdosage of the tumor, and/or overdosage in organs-at-risk. A solution is adaptive radiotherapy guided by magnetic resonance imaging (MRI). MRI allows for imaging of target volumes and organs-at-risk before and during treatment delivery with superb soft tissue contrast in an...

Introduction: The lack of radiation-attenuating tuning capacitors in high impedance coils (HICs) make HICs an interesting building block of receive arrays for MRI-guided radiotherapy (MRIgRT). Additionally, their flexibility and limited channel coupling allow for low-density support materials, which are likely to be more radiation transparent (radi...

The purpose of this study is to investigate the attenuation characteristics of a novel RF coil, which is the first coil that is solely dedicated to MR guided radiotherapy with an 1.5T MR-linac. Additionally, we investigated the impact of the treatment beam on the MRI performance of this RF coil. First, the attenuation characteristics of the RF coi...

Antibody detection is of fundamental importance in many diagnostic and bioanalytical assays, yet current detection techniques tend to be laborious and/or expensive. We present a new sensor platform (LUMABS) based on Bioluminescence Resonance Energy Transfer (BRET) that allows detection of antibodies directly in solution using a smartphone as the so...