Quality control of superficial hyperthermia by treatment evaluation

Self Cite

116

Quality assurance guidelines are essential to provide uniform execution of clinical trials and treatment in the application of hyperthermia. This document provides definitions for a good hyperthermia treatment and identifies the clinical conditions where a certain hyperthermia system can or cannot adequately heat the tumour volume. It also provides brief description of the characteristics and performance of the current electromagnetic (radiative and capacitive), ultrasound and infra-red heating techniques. This information helps to select the appropriate heating technique for the specific tumour location and size, and appropriate settings of the water bolus and thermometry. Finally, requirements of staff training and documentation are provided. The guidelines in this document focus on the clinical application and are complemented with a second, more technical quality assurance document providing instructions and procedure to determine essential parameters that describe heating properties of the applicator for superficial hyperthermia. Both sets of guidelines were developed by the ESHO Technical Committee with participation of senior STM members and members of the Atzelsberg Circle.

Section: Introductionmentioning

confidence: 99%

Quality assurance guidelines for superficial hyperthermia clinical trials: I. Clinical requirements

Trefná

Crezee²,

Schmidt

et al. 2017

Self Cite

116

“…Clinically, hyperthermia has been delivered using external and/or interstitial heating applicators employing a range of energy modalities [3,4]. Monitoring of temperatures during hyperthermia has most commonly been achieved with invasive temperature sensors [5], and more recently with magnetic resonance imaging (MRI) [6]. As early as the mid 1980s it was confirmed that significant cell killing could occur when the tissues were heated to >42 °C for longer duration [7,8].…”

Section: Introductionmentioning

confidence: 99%

Localised hyperthermia in rodent models using an MRI-compatible high-intensity focused ultrasound system

Bing

Nofiele

Staruch

et al. 2015

Purpose Localised hyperthermia in rodent studies is challenging due to the small target size. This study describes the development and characterisation of an MRI-compatible high-intensity focused ultrasound (HIFU) system to perform localised mild hyperthermia treatments in rodent models. Material and methods The hyperthermia platform consisted of an MRI-compatible small animal HIFU system, focused transducers with sector-vortex lenses, a custom-made receive coil, and means to maintain systemic temperatures of rodents. The system was integrated into a 3T MR imager. Control software was developed to acquire images, process temperature maps, and adjust output power using a proportional-integral-derivative feedback control algorithm. Hyperthermia exposures were performed in tissue-mimicking phantoms and in a rodent model (n = 9). During heating, an ROI was assigned in the heated region for temperature control and the target temperature was 42 °C; 30 min mild hyperthermia treatment followed by a 10-min cooling procedure was performed on each animal. Results 3D-printed sector-vortex lenses were successful at creating annular focal regions which enables customisation of the heating volume. Localised mild hyperthermia performed in rats produced a mean ROI temperature of 42.1 ± 0.3 °C. The T10 and T90 percentiles were 43.2 ± 0.4 °C and 41.0 ± 0.3 °C, respectively. For a 30-min treatment, the mean time duration between 41–45 °C was 31.1 min within the ROI. Conclusions The MRI-compatible HIFU system was successfully adapted to perform localised mild hyperthermia treatment in rodent models. A target temperature of 42 °C was well-maintained in a rat thigh model for 30 min.

“…For the best case scenario with a perpendicular E-field direction, we predicted that 64 W is enough to achieve 43 C in healthy tissue, i.e. a power level comparable to the average power of 56.4 W [16] as applied in actual clinical hyperthermia treatments.…”

Section: Discussionmentioning

confidence: 99%

“…the maximum temperature allowed during the treatment [16], in all scenarios (no port-a-cath, silicone port-a-cath, and metal port-a-cath). The SAR pattern generated by the LCA in the EM simulations was used as the input source for thermal simulations.…”

Section: Thermal Modelsmentioning

confidence: 99%

Impact of silicone and metal port-a-cath implants on superficial hyperthermia treatment quality

Trujillo-Romero

Paulides

Drizdal

et al. 2014

Self Cite

Purpose: A port-a-cath is a device implanted under the skin for continuous drug administration. It is composed of a catheter and a silicone or metal reservoir. A simulation study was done to assess the impact of a port-a-cath implant on the quality of superficial hyperthermia treatments applied using the Lucite cone applicator (LCA). Methods: Specific absorption rate (SAR) and temperature distributions were predicted using SEMCAD-X (version 14.8). We simulated 72 arrangements: two LCA-implant set-ups (central port-a-cath or at an edge below the LCA footprint), six translations of the LCA per set-up, two LCA orientations (Parallel or perpendicular electric field direction) per set-up, two implant materials (silicon or metal) and a control without port-a-cath. Treatment quality was quantified by the average 1 g SAR coverage (CV 25% ), i.e. volume within the 25% iso-SAR surface, and the volume within the 40 C iso-temperature surface (CV 40 C ). Results: CV 25% reduced with a silicon port-a-cath located below the LCA footprint. In the worst scenario, only 64% of the CV 25% of the control set-up was achieved. For a metal port-a-cath below the LCA aperture, dramatic reductions of CV 25% were predicted: worst scenario down to 12.1% of the control CV 25% . For the CV 40 C the worst case values were 74.5% and 6.5%, for silicon and metal implants, respectively. Conclusions: A silicone port-a-cath below the LCA had a smaller effect on treatment quality than a metal implant. Based on this study we recommend verifying heating quality by 3D patient-specific treatment planning when a port-a-cath is located below the footprint of the applicator.