Eva Onjukka

Eva Onjukka

Affiliated to research

About me

  • Medical physicist at Karolinska University Hospital and R&D co-ordinator for external-beam radiotherapy physics
  • PhD at the University of Liverpool, UK, in 2011
  • Active member of European Society for Radiotherapy and Oncology (ESTRO)
  • Research interests: Radiobiological modelling, Radiotherapy side effects, optimisation of radiotherapy treatment plans, use of MR in treatment planning
  • 7 completed Master’s projects, 2 ongoing PhD projects
  • Also published under the name of Eva Rutkowska

Research description

Every year around 4000 patients are treated with radiotherapy at Karolinska University hospital. Most patients receive external-beam radiotherapy but the hospital also offers treatments with brachytherapy, radiosurgery and proton therapy. The treatments are optimised by a team of medical physicists, oncologists and nurses and we have many projects aiming to learn from the result of different treatments and continuously improve treatment methods.  Since every patient has a unique anatomy and each tumour to be treated presents differently, an optimised treatment results in very different dose distributions for each patient. The probability of side effects from radiotherapy depends strongly on the 3D dose-distribution in each organ at risk. Detailed information about the treatment plans are saved in the treatment planning system, including the full dose distribution in each part of the patient.

Projects in head & neck cancer

Since 2013, the follow-up data of all head & neck cancer patients are entered into an electronic quality registry, including side-effect data. Currently the registry contains over a thousand patients, sometimes with several years of follow-up after radiotherapy. In combination with the treatment data, these offer many opportunities to develop models of the effect of the treatment and systematically learn from past experience. As R&D co-ordinator for external-beam radiotherapy physics I run or participate in several such projects, in close co-operation with other physicists and oncologists.

Predictive modelling of xerostomia

A multivariate model of the risk of developing xerostomia after radiotherapy of head&neck cancer has been developed based on 753 patients. As the model is based on registry data (real-life data) rather than data from clinical studies, as is more common in the literature, the cohort is unusually large and models suitable for decision support can be developed. The results have been published and the models will be further refined and adapted for clinical use.

Retreatment of head&neck cancer

Patients who have received radiotherapy twice or more in the head & neck region have been studied retrospectively to determine suitable indications for retreatment. Tumour control and side effects are associated with the size of the volume receiving ‘double’ dose and other relevant variables. This work is part of a PhD project for which I am a co-supervisor and the first results were published in 2020.

As a part of this project we also study the reliability of deformable registration of CT images for purposes of accumulating the dose from several courses of radiotherapy. A publication is planned for 2021.

Identification of organs at risk for swallowing dysfunction

A voxel-based analysis aiming to identify which parts of the anatomy which, if damaged from radiation, can cause swallowing dysfunction is ongoing. I’m developing a routine for automatic registration of CT images to a standard anatomy in order to detect in which areas the radiation dose differs between patients with and without swallowing dysfunction, respectively. Using an alternative approach, different anatomical structures are delineated (segmented) and dose statistics from these structures can be compared to the outcome. Here, the possibility of using AI-based automatic segmentation of the structures of interest is explored.

Projects in SBRT

Since SBRT (stereotactic body radiotherapy) was pioneered at Karolinska University in the early 1990’s, many patients with many different diagnoses have been treated with this technique. I participate in several projects aiming to evaluate the effect of the treatment, related to the unique dose distribution delivered to each patient.

HILUS retrospective

HILUS is a multi-centre study of the effect of SBRT for patients with centrally located lung tumours. Several cases of acute bleedings were observed and it is important to discover which aspects of the treatment and/or the disease which result in this side effect. In order to determine whether the radiation dose to the main bronchi affects the risk of acute bleeding a larger, retrospective, cohort will be included in the next phase of the study. Different dose/volume variables will be collected as candidates in a multivariate model of the risk of acute bleeding.

Furthermore, the uncertainty in the dose will be studied by delineating bronchi on CBCT images from each treatment fraction, followed by a registration of images and accumulation of the dose. This work will be performed in 2021 by a PhD student and a medical student.

Dose response of the brachial plexus

When apical lung tumours are treated with SBRT, the brachial plexus may receive a high dose which sometimes leads to brachial plexopaty. In 2019 we published the incidence in a cohort of 52 retrospectively analysed patients, including a mapping of the dose to the brachial plexus. In order to evaluate the tolerance of this organ, and to develop a model of plexopathy, further patients will be included in the next phase of this study.

Large tumours

The effect of SBRT for patients with large tumours (>5 cm in diameter) has been analysed retrospectively in a large cohort of patients treated for different diagnoses and tumour locations in the thorax and abdomen. A predictive model of local control has been developed, including dose/volume parameters of the tumour. An article is currently in press.