Radiobiological Evaluation of Combined Gamma Knife Radiosurgery and Hyperthermia for Pediatric Neuro-Oncology

Abstract

Combining radiotherapy (RT) with hyperthermia (HT) has been proven effective in the treatment of a wide range of tumours, but the combination of externally delivered, focused heat and stereotactic radiosurgery has never been investigated. We explore the potential of such treatment enhancement via radiobiological modelling, specifically via the linear-quadratic (LQ) model adapted to thermoradiotherapy through modulating the radiosensitivity of temperature-dependent parameters. We extend this well-established model by incorporating oxygenation effects. To illustrate the methodology, we present a clinically relevant application in pediatric oncology, which is novel in two ways. First, it deals with medulloblastoma, the most common malignant brain tumour in children, a type of brain tumour not previously reported in the literature of thermoradiotherapy studies. Second, it makes use of the Gamma Knife for the radiotherapy part, thereby being the first of its kind in this context. Quantitative metrics like the biologically effective dose (BED) and the tumour control probability (TCP) are used to assess the efficacy of the combined plan.

Antenna Arrangement in UWB Helmet Brain Applicators for Deep Microwave Hyperthermia

“…This step was included to model the cooling effect of the water bolus in SAR, as the EM losses are effectively counteracted by the convective heat extraction [15]. Additionally, the exclusion of such a thick layer of patient surface was motivated by the knowledge that the most prominent hot-spot was expected to arise in the deep-seated pocket of CSF caudal to the target volume [26], while the peripheral strati of CSF were kept within safe temperatures by the joint action of the water bolus and the naturally high perfusion rate of gray matter [13]. Altogether, these measures ensured a high degree of correlation between the SAR and the resulting temperature distribution.…”

“…Preliminary results suggest that high-quality heating can be better achieved when the array configuration is customized to the specific tumor location, shape and size [25]. By means of radio-biological modeling, the addition of hyperthermia to the treatment of medulloblastoma has been shown to yield a considerable theoretical boost in the biologically equivalent dose (BED) when combined with stereotactic radiosurgery [26].…”

Biological treatment evaluation in thermoradiotherapy: application in cervical cancer patients

“…Previous studies applied biological modelling for thermoradiotherapy using simulated temperature distributions to obtain more insight into the impact of different treatment parameters or to explore the feasibility of hyperthermia for non-standard indications [24,[27][28][29][30][31]. So far, biological modelling has not been used for evaluation of actual clinical treatments.…”