Clinical integration of software tool VEDO for adaptive and quantitative application of phased array hyperthermia in the head and neck

Planning of combined radiotherapy and hyperthermia treatments should be performed taking the synergistic action between the two modalities into account. This work evaluates the available experimental data on cytotoxicity of combined radiotherapy and hyperthermia treatment and the requirements for integration of hyperthermia and radiotherapy treatment planning into a single planning platform. The underlying synergistic mechanisms of hyperthermia include inhibiting DNA repair, selective killing of radioresistant hypoxic tumour tissue and increased radiosensitivity by enhanced tissue perfusion. Each of these mechanisms displays different dose-effect relations, different optimal time intervals and different optimal sequences between radiotherapy and hyperthermia. Radiosensitisation can be modelled using the linear-quadratic (LQ) model to account for DNA repair inhibition by hyperthermia. In a recent study, an LQ model-based thermoradiotherapy planning (TRTP) system was used to demonstrate that dose escalation by hyperthermia is equivalent to $10 Gy for prostate cancer patients treated with radiotherapy. The first step for more reliable TRTP is further expansion of the data set of LQ parameters for normally oxygenated normal and tumour tissue valid over the temperature range used clinically and for the relevant time intervals between radiotherapy and hyperthermia. The next step is to model the effect of hyperthermia in hypoxic tumour cells including the physiological response to hyperthermia and the resulting reoxygenation. Thermoradiotherapy planning is feasible and a necessity for an optimal clinical application of hyperthermia combined with radiotherapy in individual patients.

Section: Further Researchmentioning

confidence: 99%

Thermoradiotherapy planning: Integration in routine clinical practice

Crezee

Leeuwen

Oei

et al. 2015

“…Some research groups explore the possibility to combine treatment planning with MRI feedback [81][82][83], but this requires MR-compatibility of the heating system. Therefore also on-line adaptive use of treatment planning is currently investigated [84][85][86]. The feasibility has been demonstrated by a study, which showed that there is a correlation between measured and predicted changes in SAR after phase steering [54].…”

Section: Discussionmentioning

confidence: 99%

Planning, optimisation and evaluation of hyperthermia treatments

Kok

Kotte

Crezee

2017

Background: Hyperthermia treatment planning using dedicated simulations of power and temperature distributions is very useful to assist in hyperthermia applications. This paper describes an advanced treatment planning software package for a wide variety of applications. Methods: The in-house developed Cþþ software package Plan2Heat runs on a Linux operating system. Modules are available to perform electric field and temperature calculations for many heating techniques. The package also contains optimisation routines, post-treatment evaluation tools and a sophisticated thermal model enabling to account for 3D vasculature based on an angiogram or generated artificially using a vessel generation algorithm. The use of the software is illustrated by a simulation of a locoregional hyperthermia treatment for a pancreatic cancer patient and a spherical tumour model heated by interstitial hyperthermia, with detailed 3D vasculature included. Results: The module-based set-up makes the software flexible and easy to use. The first example demonstrates that treatment planning can help to focus the heating to the tumour. After optimisation, the simulated absorbed power in the tumour increased with 50%. The second example demonstrates the impact of accurately modelling discrete vasculature. Blood at body core temperature entering the heated volume causes relatively cold tracks in the heated volume, where the temperature remains below 40 C. Conclusions: A flexible software package for hyperthermia treatment planning has been developed, which can be very useful in many hyperthermia applications. The object-oriented structure of the source code allows relatively easy extension of the software package with additional tools when necessary for future applications.

“…At our institute, HTP is mandatory prior to HYPERcollar treatments to optimise amplitude and phase settings for each channel in the phase array, and the patient position in the applicator [11,12,16]. HTP also ensures that the specific absorption rate (SAR) in critical tissues such as spinal cord does not exceed safety limits of 60 W/kg [13]. Our in house tool VEDO allows technicians to adjust amplitude and phase settings during treatment according to measured temperatures and patient feedback [13].…”

Section: Hyperthermia Treatment Planningmentioning

confidence: 99%

“…HTP also ensures that the specific absorption rate (SAR) in critical tissues such as spinal cord does not exceed safety limits of 60 W/kg [13]. Our in house tool VEDO allows technicians to adjust amplitude and phase settings during treatment according to measured temperatures and patient feedback [13]. Superficial HTP setups were created manually by an experienced physicist (TD) in order to overlap the CTV with at least ten millimetres by the LCA or CSA aperture.…”

Section: Hyperthermia Treatment Planningmentioning

confidence: 99%

“…Our in-house developed visualisation tool for electromagnetic dosimetry and optimisation, i.e. VEDO, is used to optimise amplitude and phase settings during treatment according to measured temperatures and patient feedback [13]. Pre-treatment planning in superficial hyperthermia is not regularly required and is applied only in special situations: if the CTV is 1) deeper than 40 mm, 2) close to critical organs or 3) includes metal implants [14,15].…”

Section: Introductionmentioning

confidence: 99%

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Hyperthermia treatment planning guided applicator selection for sub-superficial head and neck tumors heating

Drizdal

Paulides

Holthe

et al. 2017

Self Cite

Purpose: In this study, we investigated the differences in hyperthermia treatment (HT) quality between treatments applied with different hyperthermia systems for sub-superficial tumours in the head and neck (H&N) region. Materials and methods: In 24 patients, with a clinical target volume (CTV) extending up to 6 cm from the surface, we retrospectively analysed the predicted HT quality achievable by two planar applicator arrays or one phased-array hyperthermia system. Hereto, we calculated and compared the specific absorption rate (SAR) and temperature distribution coverage of the CTV and gross tumour volume (GTV) for the Lucite cone applicator (LCA: planar), current sheet applicator (CSA: planar) and the HYPERcollar (phased-array). Results: The HYPERcollar provides better SAR coverage than planar applicators if the target region is fully enclosed by its applicator frame. For targets extending outside the HYPERcollar frame, sufficient SAR coverage (25% target coverage, i.e. TC25 ! 75%) can still be achieved using the LCA when the target is fully under the LCA aperture and not deeper than 50 mm from the patient surface. Conclusion: Simulations predict that the HYPERcollar (hence also its successor the HYPERcollar3D) is to be preferred over planar applicators such as LCA and current sheet applicator in sub-superficial tumours in the H&N region when used within specifications. ARTICLE HISTORY