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AbstractPurpose The heating characteristics of water-filtered infrared-A (wIRA) radiation were investigated in vivo in two body regions of healthy humans according to the quality standards of the European Society for Hyperthermic Oncology (ESHO) using an irradiance (infrared-A) of 146 W m−2 as recommended for clinical superficial hyperthermia (HT).Methods wIRA was applied to the abdominal wall and lumbar region for 60 min. Skin surface temperature was limited to ≤43 °C. Tissue temperatures were measured invasively at 1-min intervals before, during and after wIRA exposure using five fiber-optical probes at depths of 1–20 mm.Results Significant differences between body regions occurred during the heating-up phase at depths of 5–15 mm. Thermal steady states were reached at depths ≤5 mm after exposures of 5–6 min, and ≤20 mm after 20 min. On average, the minimum requirements of ESHO were exceeded in both regions by the following factors: ≈3 for the heating rate, ≈2 for the specific absorption rate and ≈1.4 for the temperature rise. Tissue depths with T90 ≥ 40 °C and T50 > 41 °C were ≤10 mm, and ≤20 mm for Tmax ≤ 43 °C. The temperature decay time after termination of irradiation was 1–5 min. Corresponding temperatures were ≤42.2 °C for CEM43 and ≤41.8 °C for CEM43T90, i.e., they are inadequate for direct thermal cell killing.Conclusions Thermography-controlled wIRA-HT complies with the ESHO criteria for superficial HT as a radiosensitizer and avoids the risk of thermal skin toxicity.

Purpose To evaluate the long-term efficacy of combined radiotherapy (RT) and hyperthermia (HT) in a large mono-institutional cohort of breast cancer (BC) patients affected by recurrent, newly diagnosed non-resectable or high risk resected tumor.Materials and methods Records of BC patients treated with RT + HT between 1995 and 2018 were retrospectively analyzed. RT doses of 50–70 Gy concurrent to a twice per week superficial HT were applied. For HT, a temperature between 41 and 42 °C was applied for approximately 1 h. Primary endpoint was local control (LC), secondary endpoints comprised toxicity, overall survival (OS), and progression-free survival (PFS).Results A total of 191 patients and 196 RT + HT treatments were analyzed. In 154 cases (78.6%) RT + HT was performed for patients with recurrent BC. Among these, 93 (47.4% of the entire cohort) had received RT prior to RT + HT. Median follow up was 12.7 years. LC at 2, 5, and 10 years was 76.4, 72.8, and 69.5%, respectively. OS at 2, 5, and 10 years was 73.5, 52.3, and 35.5%, respectively. PFS at 2, 5, and 10 years was 55.6, 41, and 33.6%, respectively. Predictive factors for LC were tumor stage, distant metastases, estrogen/progesterone receptor expression, resection status and number of HT fractions. At multivariate analysis tumor stage and receptor expression were significant. No acute or late toxicities higher than grade 3 were observed.Conclusion Combined RT + HT offers long-term high LC rates with acceptable toxicity for patients with recurrent, newly diagnosed non-resectable or resected BC at high risk of relapse.

Simple Summary: Hyperthermia (HT) is a clinical treatment modality that is used in combination with radiotherapy (RT) and/or chemotherapy (CT) in cancer patients to enhance the effect of ionizing radiation and chemotherapeutic drugs without worsening toxicity. Yet there is very little clinical evidence about the quality of life (QoL) after combination treatments, including HT, despite the fact that QoL has gained increasing importance in assessing the side effects of oncological therapies. In this retrospective study, the QoL of patients treated with HT in combination with radio(chemo)therapy (RCT) with curative or palliative intent was assessed by the EORTC QLQ-C30 questionnaire. The results of this analysis suggested that the combination of RCT and HT stabilizes or improves QoL for a clinically relevant time period after treatment. Hyperthermia (HT) in combination with radio(chemo)therapy (RCT) is a well-established cancer treatment strategy. This report analyses the quality of life (QoL), toxicity and survival outcomes in patients with different tumor entities who received HT in combination with RCT. The primary endpoint of this study was the assessment of QoL scale items 3 and 12 months after treatment in patients who were treated with palliative intent and curative intent, respectively. The secondary endpoints of this study were acute toxicities, 1-year overall survival (OS), and local progression-free survival (LPFS). Patients treated with curative intent experienced significant improvement in emotional functioning (EF), social functioning (SF), financial difficulties (FI) and insomnia (SL) 12 months after treatment. Patients had significantly improved FI and pain (PA) three months after palliative treatment. Acute toxicity of grade 3 or more was 26% during treatment and 4% after three months. The 1-year OS rates were 90% (95% CI: 79–96%) and 44% (95% CI: 31–59%) for patients treated with curative and palliative RCT combined with HT, respectively. Moreover, the 1-year LPFS rates were 94% (95% CI: 84–98%) for patients treated with curative intent and 64% (95% CI: 50–77%) for palliative patients. In summary, combined RCT and HT stabilized or improved QoL scale items for both curative and palliative indications. [ABSTRACT FROM AUTHOR]

The heating characteristics of water-filtered infrared-A (wIRA) radiation were investigated in vivo in two body regions of healthy humans according to the quality standards of the European Society for Hyperthermic Oncology (ESHO) using an irradiance (infrared-A) of 146 W m−2 as recommended for clinical superficial hyperthermia (HT). wIRA was applied to the abdominal wall and lumbar region for 60 min. Skin surface temperature was limited to ≤43 °C. Tissue temperatures were measured invasively at 1-min intervals before, during and after wIRA exposure using five fiber-optical probes at depths of 1–20 mm. Significant differences between body regions occurred during the heating-up phase at depths of 5–15 mm. Thermal steady states were reached at depths ≤5 mm after exposures of 5–6 min, and ≤20 mm after 20 min. On average, the minimum requirements of ESHO were exceeded in both regions by the following factors: ≈3 for the heating rate, ≈2 for the specific absorption rate and ≈1.4 for the temperature rise. Tissue depths with T90 ≥ 40 °C and T50 > 41 °C were ≤10 mm, and ≤20 mm for Tmax ≤ 43 °C. The temperature decay time after termination of irradiation was 1–5 min. Corresponding temperatures were ≤42.2 °C for CEM43 and ≤41.8 °C for CEM43T90, i.e., they are inadequate for direct thermal cell killing. Thermography-controlled wIRA-HT complies with the ESHO criteria for superficial HT as a radiosensitizer and avoids the risk of thermal skin toxicity. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the long-term efficacy of combined radiotherapy (RT) and hyperthermia (HT) in a large mono-institutional cohort of breast cancer (BC) patients affected by recurrent, newly diagnosed non-resectable or high risk resected tumor. Materials and methods: Records of BC patients treated with RT þ HT between 1995 and 2018 were retrospectively analyzed. RT doses of 50–70 Gy concurrent to a twice per week superficial HT were applied. For HT, a temperature between 41 and 42 C was applied for approximately 1 h. Primary endpoint was local control (LC), secondary endpoints comprised toxicity, overall survival (OS), and progression-free survival (PFS). Results: A total of 191 patients and 196 RT þ HT treatments were analyzed. In 154 cases (78.6%) RT þ HT was performed for patients with recurrent BC. Among these, 93 (47.4% of the entire cohort) had received RT prior to RT þ HT. Median follow up was 12.7 years. LC at 2, 5, and 10 years was 76.4, 72.8, and 69.5%, respectively. OS at 2, 5, and 10 years was 73.5, 52.3, and 35.5%, respectively. PFS at 2, 5, and 10 years was 55.6, 41, and 33.6%, respectively. Predictive factors for LC were tumor stage, distant metastases, estrogen/progesterone receptor expression, resection status and number of HT fractions. At multivariate analysis tumor stage and receptor expression were significant. No acute or late toxicities higher than grade 3 were observed. Conclusion: Combined RT þ HT offers long-term high LC rates with acceptable toxicity for patients with recurrent, newly diagnosed non-resectable or resected BC at high risk of relapse. [ABSTRACT FROM AUTHOR]

Purpose The quality assurance guidelines of the European Society for Hyperthermic Oncology (ESHO) specify the requirements for appropriate superficial heating using phantoms. In this current piglet study, we have examined these requirements under in vivo conditions. Materials and Methods The evaluation is based on simultaneous, invasive temperature measurements at 8 different depths between 2 and 20 mm in the thigh of anesthetized piglets during irradiation with water-filtered infrared radiation (wIRA). Temperature probes were equally distributed in an area of 10 cm diameter of homogeneously irradiated skin. Piglets were irradiated to 126.5 mW cm−2 in the spectral range of IR-A. Results Heating rates and specific absorption rates were in full accordance with the ESHO standards. Due to early onset of thermoregulation, the desired temperature rise of 6 K at a depth of 5 mm was achieved after about 10 min of exposure, i.e. 4 min later than required for phantoms. After reaching thermal steady state, on average T90 ≥ 40 °C occurred in tissue depths up to 20 mm, T50 ≥ 41 °C up to 16 mm, and a mean CEM43T90 ≈ 1 min was calculated for depths up to 8 mm. Conclusions Piglet data are comparable with preliminary literature data assessed in vivo in the abdominal wall and in recurrent breast cancer of humans. The potential of wIRA-HT for adequate treatment of superficial tissues/cancers in the clinical setting thus is confirmed. To ensure therapeutically needed doses of wIRA-HT, irradiation times should be extended.

Purpose: The temporal and spatial formation of the temperature field and its changes during/upon water-filtered infrared-A (wIRA)-irradiation in porcine skin and subcutis were investigated in vivo in order to get a detailed physical basis for thermotherapy of superficial tumors and infections caused by thermosensitive microbial pathogens (e.g., Mycobacterium ulcerans causing Buruli ulcer). Methods: Local wIRA-hyperthermia was performed in 11 anesthetized piglets using 85.0 mW cm−2, 103.2 mW cm−2 and 126.5 mW cm−2, respectively. Invasive temperature measurements were carried out simultaneously in 1-min intervals using eight fiber-optical probes at different tissue depths between 2 and 20 mm, and by an IR thermometer at the skin surface. Results: Tissue temperature distribution depended on incident irradiance, exposure time, tissue depths and individual ‘physiologies’ of the animals. Temperature maxima were found at depths between 4 and 7 mm, exceeding skin surface temperatures by about 1–2 K. Tissue temperatures above 37 °C, necessary to eradicate M. ulcerans at depths

Purpose: The quality assurance guidelines of the European Society for Hyperthermic Oncology (ESHO) specify the requirements for appropriate superficial heating using phantoms. In this current piglet study, we have examined these requirements under in vivo conditions. Materials and methods: The evaluation is based on simultaneous, invasive temperature measurements at 8 different depths between 2 and 20 mm in the thigh of anesthetized piglets during irradiation with water-filtered infrared radiation (wIRA). Temperature probes were equally distributed in an area of 10 cm diameter of homogeneously irradiated skin. Piglets were irradiated to 126.5 mW cm-2 in the spectral range of IR-A. Results: Heating rates and specific absorption rates were in full accordance with the ESHO standards. Due to early onset of thermoregulation, the desired temperature rise of 6 K at a depth of 5 mm was achieved after about 10 min of exposure, i.e. 4 min later than required for phantoms. After reaching thermal steady state, on average T 90 ≥ 40 °C occurred in tissue depths up to 20 mm, T 50 ≥ 41 °C up to 16 mm, and a mean CEM43 T 90 ≈ 1 min was calculated for depths up to 8 mm. Conclusions: Piglet data are comparable with preliminary literature data assessed in vivo in the abdominal wall and in recurrent breast cancer of humans. The potential of wIRA-HT for adequate treatment of superficial tissues/cancers in the clinical setting thus is confirmed. To ensure therapeutically needed doses of wIRA-HT, irradiation times should be extended. [ABSTRACT FROM AUTHOR]

Purpose: The temporal and spatial formation of the temperature field and its changes during/upon water-filtered infrared-A (wIRA)-irradiation in porcine skin and subcutis were investigated in vivo in order to get a detailed physical basis for thermotherapy of superficial tumors and infections caused by thermosensitive microbial pathogens (e.g., Mycobacterium ulcerans causing Buruli ulcer). Methods: Local wIRA-hyperthermia was performed in 11 anesthetized piglets using 85.0mW cm-2, 103.2mW cm-2 and 126.5mW cm-2, respectively. Invasive temperature measurements were carried out simultaneously in 1-min intervals using eight fiber-optical probes at different tissue depths between 2 and 20 mm, and by an IR thermometer at the skin surface. Results: Tissue temperature distribution depended on incident irradiance, exposure time, tissue depths and individual 'physiologies' of the animals. Temperature maxima were found at depths between 4 and 7 mm, exceeding skin surface temperatures by about 1-2 K. Tissue temperatures above 37 °C, necessary to eradicate M. ulcerans at depths <20 mm, were reached reliably. Conclusions: wIRA-hyperthermia may be considered as a novel therapeutic option for treatment of local skin infections caused by thermosensitive pathogens (e.g., in Buruli ulcer). To ensure temperatures required for heat treatment of superficial tumors deeper than 4 mm, the incident irradiance needed can be controlled either by (a) invasive temperature measurements or (b) control of skin surface temperature and considering possible temperature increases up to 1-2 K in underlying tissue. [ABSTRACT FROM AUTHOR]

Thermography-controlled, water-filtered infrared-A (wIRA) is a novel, effective and approved heating technique listed in the ESHO quality assurance guidelines for superficial hyperthermia clinical trials (2017). In order to assess the special features and the potential of wIRA-hyperthermia (wIRA-HT), detailed and updated information about its physical and photobiological background is presented. wIRA allows for (a) application of high irradiances without skin pain and acute grade 2-4 skin toxicities, (b) prolonged, therapeutically relevant exposure times using high irradiances (150-200 mW/cm2) and (c) faster and deeper heat extension within tissues. The deeper radiative penetration depth is mainly caused by forward Mie-scattering. At skin surface temperatures of 42-43 °C, the effective heating depth is 15 mm (T ≥ 40 °C) and 20 mm (T ≥ 39.5 °C). Advantages of wIRA include its contact-free energy input, easy power steering by a feed-back loop, extendable treatment fields, real-time and noninvasive surface temperature monitoring with observation of dynamic changes during HT, and - if necessary - rapid protection of temperature-sensitive structures. wIRA makes the compliant heating of ulcerated and/or bleeding tumors possible, allows for HT of irregularly shaped and diffusely spreading tumors, is independent of individual body contours, allows for very short 'transits' between HT and RT (1-4 min) or continuous heating between both therapeutic interventions. New treatment options for wIRA-HT may include malignant melanoma, vulvar carcinoma, skin metastases of different primary tumors, cutaneous T-and B-cell lymphoma, large-area hemangiomatosis, inoperable squamous cell, basal cell and eccrine carcinoma of the skin with depth extensions ≤20 mm. [ABSTRACT FROM AUTHOR]

Purpose:Evaluation of the efficacy and toxicity of a new setup of thermographically controlled water-filtered infra-red-A (wIRA) superficial hyperthermia (HT) combined with hypofractionated re-irradiation (re-RT) to treat large-sized breast cancer recurrences. Methods:Records of 73 heavily pre-irradiated patients with 103 treatment regions, treated from September 2009 to July 2015 were retrospectively analysed. Sixty-four patients with macroscopic disease were treated with 94 regions including 46 patients with lymphangiosis carcinomatosa. Hypofractionated RT consisted of 4 Gy once per week up to a total dose of 20 Gy delivered within 1–4 min after wIRA-HT. Heating of tumour nodules and diffusely spreading cancer lesions was performed under real-time thermographic temperature monitoring, maintaining the maximum skin temperature in the ROI between 42 °C and 43 °C, achieving intratumoural temperatures up to a depth of 2 cm between 39.5 °C and 42 °C. Seventeen patients received re-re-irradiation (re-re-RT) using the same HT/RT-treatment schedule. Results:Response rates in patients with macroscopic disease: 61% CR, 33% PR, 5% NC and 1% PD. Local control throughout life time after CR of macroscopic disease: 59%. All nine patients with microscopic disease had CR and local control throughout lifetime. Only grade 1 toxicities were observed. Conclusions:Application of thermographically controlled wIRA-HT combined with extremely low-dose re-irradiation provides good local control throughout lifetime of heavily pre-treated breast cancer recurrences. The twin wIRA radiator provides a sufficiently homogeneous heat deposition for the treatment of larger areas. The time lag between HT and re-RT is substantially reduced. The possibility of re-re-RT opens new therapeutic options for the future. [ABSTRACT FROM PUBLISHER]

Local chest wall progression of chemotherapy/radiation-resistant breast cancer can result in substantial morbidity. In this retrospective review of 39 patients in this difficult clinical setting treated at Cancer Treatment Centers of America (Eastern Regional Medical Center), approximately one-half of the population experienced meaningful short-term palliation and improvement in quality of life when managed with local superficial hyperthermia plus external beam radiation.

The purpose of this study was to determine whether prediction of the 3D temperature profile for superficial hyperthermia using constant blood perfusion model could be matched to one with a temperature dependent blood perfusion. We compared three different constant blood perfusion scenarios with one temperature dependent blood perfusion using a layered model of biological tissue consisting of skin (2 mm), fat (10 mm) and muscle (108 mm). For all four scenarios the maximum temperature of 43 °C was found in the muscle tissue in the close proximity (1 – 3 mm) of fat layer. Cumulative histograms of temperature versus volume were identical for the region of 100x100x40 mm3 under the applicator aperture for the three constant blood perfusion models. For temperature dependent blood perfusion model, 85 % of the studied region was covered with the temperature equal or higher than 40 °C in comparison with 43 % for the constant blood perfusion models. Hence this study demonstrates that constant blood perfusion scenarios cannot be matched to one with a temperature dependent blood perfusion.

A transmit-array (TA)-lens-mounted hyperthermia applicator is proposed to enhance the therapeutic suitability for treatments of superficial tumors. The hyperthermia applicator, which consists of the external radiator, TA lens, and water-bolus, is designed to provide pain-free treatment of tumors. The external radiator is designed to support a uniform electromagnetic (EM) field distribution on the lens surface, and the configuration of the TA lens leads to a summation of EM energies by compensating for the phase delays for different path lengths from each elementary cell of the TA lens to the desired treatment area, which allows for optimal heat deposition at the therapeutic target. The proposed hyperthermia applicator is configured with two lenses for thermal focusing and spreading experiments. In this study, the definition of the effective treatment area (ETA) was used to evaluate thermal performance of the hyperthermia system. The calculated ETAs in two experiments (thermal focusing and spreading configurations) showed a decrease of 49% and an increase of 281%, respectively, as compared to lens-free operation. [ABSTRACT FROM PUBLISHER]

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 (CV25%), i.e. volume within the 25% iso-SAR surface, and the volume within the 40 °C iso-temperature surface (CV40 °C). Results: CV25% reduced with a silicon port-a-cath located below the LCA footprint. In the worst scenario, only 64% of the CV25% of the control set-up was achieved. For a metal port-a-cath below the LCA aperture, dramatic reductions of CV25% were predicted: worst scenario down to 12.1% of the control CV25%. For the CV40 °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. [ABSTRACT FROM AUTHOR]

A circularly rotated array for a dual polarized applicator in a superficial hyperthermia system is proposed. The applicator has a wider effective treatment area due to the 180° phase shift. The dual polarized circularly rotated array (DPCRA) suppresses overheating at the center of the array and helps evenly distribute the heat. This array provides a more effective treatment area than a lattice array when a 2 × 2 dual polarized array is fitted to the treatment area. The treatment area is 71.5% of the aperture, whereas the effective treatment areas of the 2 × 2 dual polarized lattice array (DPLA) and the single polarized array (SPA) are 57.2% and 38.6% of the same aperture, respectively. The measurement matches the simulation results without blood circulation effects. In a 2 × 2 array applicator, the proposed DPCRA has more heat uniformity than the DLA and the SPA. [ABSTRACT FROM AUTHOR]

Copyright of West Indian Medical Journal is the property of West Indian Medical Journal (WIMJ) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Hyperthermia is an effective modality for the treatment of cancer, which is mainly used in conjunction with radiotherapy as this combined treatment offers a better clinical outcome. There are many ways that hyperthermia can be applied and depends on the kind of tumor of the patients. The great advantage of this method is that it is tolerable for the majority of patients without severe toxicity. Many clinical trials have been realized in order to prove that hyperthermia in addition to radiotherapy offers an advantage in the survival and local control of patients in comparison to radiotherapy alone. Many studies have also investigated if exists any correlation between the thermal parameters of hyperthermia and the clinical outcome. This is a review of these studies and it concerns superficial hyperthermia for superficial tumors-melanoma, head and neck, breast cancer-and intracavitary hyperthermia for rectal cancer, esophageal cancer and prostate carcinoma. [ABSTRACT FROM AUTHOR]

Purpose: In vitro data demonstrate that heat-induced radiosensitisation is maximised if hyperthermia and radiotherapy are given simultaneously, with the radiation fraction delivered midway through a hyperthermia session, rather than sequentially. The long-term normal tissue toxicity of full-dose simultaneous thermoradiotherapy is unknown. Materials and methods: Patients with locally advanced breast cancer (T3, T4 or more than three involved nodes or local recurrence), no prior radiotherapy, received between four and eight sessions of simultaneous thermoradiotherapy. Hyperthermia always included the primary tumour site. In addition an electively heated sector (EHS) was included. The EHS was randomised to either medial or lateral to the tumour site, with the other side an irradiated but unheated control. As per our usual practice, patients received surgery and/or chemotherapy prior to radiotherapy. Radiation doses were 46-50 Gy followed by a boost of ≤16 Gy at 1.8-2 Gy per fraction. EHS and control sectors received the same dose. Results: A total of 57 evaluable cases with average follow-up of 79 months experienced two local and two nodal recurrences. There was no significant difference in ≥grade 2 toxicity for heated versus control sectors (LR χ2 = 0.78, p = 0.38) with no relationship between number of hyperthermia sessions and toxicity (LR χ2 = 2.90, p = 0.09). Conclusions: Simultaneous full-dose thermoradiotherapy for breast cancer is feasible and well tolerated, with no significant difference in late toxicity between electively heated and unheated control sectors. All patients had hyperthermia to the primary tumour site with excellent local control. [ABSTRACT FROM AUTHOR]

A 3D temperature field distribution of biological tissue for superficial hyperthermia using a pulse modulated microwave (PMMW) was presented. A 3D sliced homogeneous phantom was radiated by the PMMW and an infrared thermal imager was applied to image temperature distribution throughout the phantom. The period of the PMMW is 3 s and the output power is 35 W. The temperature rises by at least 3 °C in the phantom when the duty cycle varies from 1/3, 1/2, 2/3 to 1 (denoted by scenarios 1-4). Both the accumulative temperature-volume histogram and the relative depth-area ratio histogram show that the maximum temperature rise (MTR) is 6.6 and 8 °C in scenarios 2 and 3, and they are superior to scenarios 1 and 4. Furthermore, the PMMW can control temperature field distribution of biological tissue. It provides both preliminary basis for thermal volume control and new technology for temperature control and monitor in superficial hyperthermia. [ABSTRACT FROM AUTHOR]

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Steering of multi-element heating arrays for superficial hyperthermia (SHT) can be a challenge in the clinic. This is because the technician has to deal with a multiple-input multiple-output system, varying tissue dynamics, and often sparse tissue temperature data. In addition, patient feedback needs to be taken into account. Effective management of the steering task determines the quality of heating. Systematic evaluation is an effective tool to control the quality of treatments. The purpose of this manuscript is to report on a treatment evaluation flow developed for SHT at the Erasmus MC. This flow is used to secure the quality of steering as well as to stimulate general quality awareness in the hyperthermia team. All treatments are evaluated in a multidisciplinary discussion. Tools and methods were developed to enable effective and efficient evaluations. The treatment evaluation sheet is a compact and intuitive representation of power and temperature data. Trend lines and a temperature-depth plot allow a quick analysis of the steering parameters and the heating profile within the target volume. In addition, the principal statistics of applicator power, water bolus and tissue temperature values are given. Power steering data includes the number of switch-off events, interruption time and the number of steering actions. A list of basic checks and reference values for clinical data support further the treatment evaluation. These tools and the systematic treatment evaluations they facilitate, ultimately lead to consistent performance and fine tuning of the set-up and steering strategy for each individual patient. [ABSTRACT FROM AUTHOR]

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Purpose: This article summarises the evolution of microwave array applicators for heating large area chest wall disease as an adjuvant to external beam radiation, systemic chemotherapy, and potentially simultaneous brachytherapy. Methods: Current devices used for thermotherapy of chest wall recurrence are reviewed. The largest conformal array applicator to date is evaluated in four studies: (1) ability to conform to the torso is demonstrated with a CT scan of a torso phantom and MR scan of the conformal water bolus component on a mastectomy patient; (2) specific absorption rate (SAR) and temperature distributions are calculated with electromagnetic and thermal simulation software for a mastectomy patient; (3) SAR patterns are measured with a scanning SAR probe in liquid muscle phantom for a buried coplanar waveguide CMA; and (4) heating patterns and patient tolerance of CMA applicators are characterised in a clinical pilot study with 13 patients. Results: CT and MR scans demonstrate excellent conformity of CMA applicators to contoured anatomy. Simulations demonstrate effective control of heating over contoured anatomy. Measurements confirm effective coverage of large treatment areas with no gaps. In 42 hyperthermia treatments, CMA applicators provided well-tolerated effective heating of up to 500 cm2 regions, achieving target temperatures of Tmin = 41.4 ± 0.7°C, T90 = 42.1 ± 0.6°C, Tave = 42.8 ± 0.6°C, and Tmax = 44.3 ± 0.8°C as measured in an average of 90 points per treatment. Conclusion: The CMA applicator is an effective thermal therapy device for heating large-area superficial disease such as diffuse chest wall recurrence. It is able to cover over three times the treatment area of conventional hyperthermia devices while conforming to typical body contours. [ABSTRACT FROM AUTHOR]

Copyright of Strahlentherapie und Onkologie is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The purpose of this study was to determine whether prediction of the 3D temperature profile for superficial hyperthermia using constant blood perfusion model could be matched to one with a temperature dependent blood perfusion. We compared three different constant blood perfusion scenarios with one temperature dependent blood perfusion using a layered model of biological tissue consisting of skin (2 mm), fat (10 mm) and muscle (108 mm). For all four scenarios the maximum temperature of 43 °C was found in the muscle tissue in the close proximity (1 - 3 mm) of fat layer. Cumulative histograms of temperature versus volume were identical for the region of 100×100×40 mm3 under the applicator aperture for the three constant blood perfusion models. For temperature dependent blood perfusion model, 85 % of the studied region was covered with the temperature equal or higher than 40 °C in comparison with 43 % for the constant blood perfusion models. Hence this study demonstrates that constant blood perfusion scenarios cannot be matched to one with a temperature dependent blood perfusion. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine whether prediction of the 3D temperature profile for superficial hyperthermia using constant blood perfusion model could be matched to one with a temperature dependent blood perfusion. We compared three different constant blood perfusion scenarios with one temperature dependent blood perfusion using a layered model of biological tissue consisting of skin (2 mm), fat (10 mm) and muscle (108 mm). For all four scenarios the maximum temperature of 43 °C was found in the muscle tissue in the close proximity (1 - 3 mm) of fat layer. Cumulative histograms of temperature versus volume were identical for the region of 100×100×40 mm³ under the applicator aperture for the three constant blood perfusion models. For temperature dependent blood perfusion model, 85 % of the studied region was covered with the temperature equal or higher than 40 °C in comparison with 43 % for the constant blood perfusion models. Hence this study demonstrates that constant blood perfusion scenarios cannot be matched to one with a temperature dependent blood perfusion. [ABSTRACT FROM AUTHOR]

In this article, we evaluated a planar microwave applicator for in vivo superficial hyperthermia treatments on small tumors in the mouse mimicking treatments for human neoplasms. The design of the applicator, was challenged by the small dimensions of the tumors and unwanted diffusion of heating in the tumor-bearing animals. The required solution was to limit the penetration of microwaves in the depth of the tissue maintaining the full efficacy of hyperthermia. The study was firstly performed by computer simulations of SAR distribution inside a flat homogeneous phantom, considering various thicknesses of the integrated water bolus. Simulations, validated by the measurements, were also used to evaluate the impedance matching. Further tests were performed on homogeneous agar phantom to simulate the temperature distribution in the biological tissue and to preliminary assess the possible modality and schedule of microwave hyperthermia delivery. The in vivo experiments showed the evidence of direct microwave-induced heating and damage of the melanoma tissue in a range of penetration coherent both with computer simulations and phantom studies. The described approach appears perspective for designing limited-microwave-delivery applicators tailored for treatments of human superficial tumors and pre-tumoral lesions. [ABSTRACT FROM AUTHOR]

Introduction: Contact flexible microstrip applicators (CFMA) are applied for superficial hyperthermia. In the clinic these flexible applicators are mostly applied bent along the body curvature. This paper investigates the specific absorption rate (SAR) patterns of CFMA applicators, when bent around an elliptical tissue-equivalent phantom. Methods: The 2H (aperture size 14.8 × 14.3 cm2), 3H (28.7 × 20.7 cm2), 4H (19.6 × 19.6 cm2) and 5H (19.7 × 28.5 cm2) applicators were examined. Measurements were performed for the 5H applicator; existing measurement data were analysed for the 3H applicator. Finite difference time domain (FDTD) simulations with a resolution of 2 × 2 × 1 mm3 were performed for all applicators. Applicators were bent around the top and the side of the elliptical phantom to examine different curvatures. The SAR deposition, effective field size (EFS) and effective heating depth (EHD) were evaluated and compared to results for straight applicators. Results: Bending the applicators generally yielded a focusing effect of the SAR, which was most pronounced with a strong curvature, but especially the 5H applicator showed a stronger power absorption at the sides of the applicator, compared to the centre region. The EFS became smaller when bending the applicators; this effect was also more pronounced for a strong curvature. The EHD increased for bent applicators, but the degree depended strongly on the location. Conclusion: The behaviour of bent CFMA applicators is not trivial and the SAR deposition is not similar for all applicators. The EFS decreases and the EHD increases, but very locally. Therefore, it is generally advisable to analyse the SAR distribution of flexible applicators in both straight and bent state. [ABSTRACT FROM AUTHOR]

Hyperthermia is a powerful radiosensitizer for treatment of superficial tumors. This requires body conformal antennas with a power distribution as homogeneous as possible over the skin area. The contact flexible microstrip applicators (CFMA) operating at 434 MHz exist in several sizes, including the large size 3H and 5H. This paper investigates the behavior of the electromagnetic fields for the 3H and 5H CFMA in both flat and curved configurations, and the impact on performance parameters like the penetration depth (PD) and the effective heating depth (EHD). The underlying theory behind the electromagnetic behavior in curved situations is presented as well as numerical simulations of both flat and curved configurations. The results are compared to measurements of the electromagnetic field distributions in a cylindrical patient model. Due to their large size multimode solutions may exist, and our results confirm their existence. These multimode solutions affect both the power distribution and PD/EHD, with a dependence on applicator curvature. Therefore, the performance parameters like PD and EHD need to be carefully assessed when bending large size CFMA applicators to conform to the patient body. This conclusion also holds for other types of large size surface current applicators. [ABSTRACT FROM AUTHOR]

Purpose: This study evaluated psychological stress reactions during hyperthermia (HT) treatments and compared them to systemic stress reactions. Materials and methods: 27 patients with malignant disease were treated with superficial or regional hyperthermia. Cortisol and the catecholamines adrenaline and noradrenaline in venous blood were used as markers of psychological stress. The anxiety proneness of the patients was evaluated with a trait-anxiety inventory. Blood pressure and heart rate were markers of systemic stress. Patients were first grouped by superficial or regional treatment and then into two subgroups: anxious and non-anxious patients. Results: The time course of the cortisol concentration of the superficial group showed a slight but significant decrease and that of the regional group an increase. The cortisol concentration of the regional group was sometimes slightly but significantly higher than in the superficial group, and in the group of anxious patients higher than in the group of non-anxious patients. The changes in time courses and differences in groups were not as pronounced for the catecholamine concentrations. Heart rate and blood pressure showed a significant increase only in the regional group, and there was no significant difference between the regional and the superficial groups. None of the variables showed a significant difference between the initial and the subsequent treatments; all lay well within the normal physiological range. Conclusions: These standard hyperthermia treatments are not excessively stressful, either systemically or psychologically. The different behaviours of the variables confirm that it makes sense to consider systemic stress as well as psychological reactions. [ABSTRACT FROM AUTHOR]

Introduction: Contact flexible microstrip applicators (CFMA), operating at 434 MHz, are applied at the Academic Medical Center (AMC) for superficial hyperthermia (e.g. chest wall recurrences and melanoma). This paper investigates the performance of CFMA, evaluating the stability of the specific absorption rate (SAR) distribution, effective heating depth (EHD) and effective field size (EFS) under different conditions. Methods: Simulations were performed using finite differences and were compared to existing measurement data, performed using a rectangular phantom with a superficial fat-equivalent layer of 1 cm and filled with saline solution. The electrode plates of the applicators measure ∼7 × 20, 29 × 21 and 20 × 29 cm2. Bolus thickness varied between 1 and 2 cm. The impact of the presence of possible air layers between the rubber frame and the electrodes on the SAR distribution was investigated. Results: The EHD was ∼1.4 cm and the EFS ranged between ∼60 and ∼300 cm2, depending on the applicator type. Both measurements and simulations showed a split-up of the SAR focus with a 2 cm water bolus. The extent and location of air layers has a strong influence on the shape and size of the iso-SAR contours with a value higher than 50%, but the impact on EFS and EHD is limited. Conclusion: Simulations, confirmed by measurements, showed that the presence of air between the rubber and the electrodes changes the iso-SAR contours, but the impact on the EFS and EHD is limited. [ABSTRACT FROM AUTHOR]

Purpose: To demonstrate the benefits of treatment planning in superficial hyperthermia. Materials and methods: Five patient cases are presented, in which treatment planning was applied to troubleshoot treatment-limiting hotspots, to select the optimum applicator type and orientation, to assess the risk associated with metallic implants, to assess the feasibility of heating a deeper seated tumour, and to analyse the effective SAR coverage resulting from arrays of multiple incoherent applicators. FDTD simulation tools were used to investigate treatment options, either based on segmented or simplified anatomies. Results: The background, approach and model implementation are presented per case. SAR cross-sections, profiles and isosurfaces are visualized to predict the effective SAR coverage of the target and the location of the maximum power absorption. In addition, the followed treatment strategy and the implications for the clinical treatment are given: for example, higher temperatures, relief of treatment limiting hot-spots or increased power input. Conclusions: Treatment planning in superficial hyperthermia can be applied to improve clinical routine. Its application supports the selection of the optimum technique in non-standard cases, leading to direct benefits for the patient. In addition, treatment planning has shown to be an excellent tool for education and training for hyperthermia technicians and physicians. [ABSTRACT FROM AUTHOR]

Purpose: The research presented in this work investigates the influence of the water bolus temperature on temperature distributions in tissue during superficial hyperthermia treatments using Lucite cone applicators. The goal of the research was to develop a guideline for the selection of the water bolus temperature based on 3-D electromagnetic and thermal modelling. Methods: A 3-D model was set up to simulate an abstraction of the treatment. In the model a convection coefficient for the water bolus to skin surface was employed. In order to simulate the heat balance as realistically as possible, convection coefficients were measured for different water boluses and ranged from 70-152 W (m2 K)-1. The model was evaluated by simulating three clinical treatments and comparing the outcome of the model to the clinical measurements. Results: The model was found to predict the temperature distribution well on a global view; root mean square errors between 0.66-1.5°C were found for the three treatments. For some temperature probes a deviation of 1.5-2.0°C between measured and predicted temperature was found. These large deviations can be explained by local variations in cooling by blood vessels, tissue inhomogeneity, a varying convection coefficient of the water bolus and of course the complexity of the anatomy. Conclusions: The model was used to set up guidelines for the water bolus temperature selection in clinical practice for the target depths and applicator arrays used in the Rotterdam Erasmus Medical Center. [ABSTRACT FROM AUTHOR]

Purpose : This effort describes a third-party performance evaluation of a novel, commercial, dual-armed Archimedean spiral array hyperthermia applicator. The applicator is analysed for its ability to couple efficiently into muscle equivalent phantom loads, operate over a broad bandwidth to help accommodate variable tissue properties and generate predictable and repeatable SAR contours that are adaptable to clinically probable disease shapes. Materials and methods : Characterization of the applicator includes E-field and return-loss measurements in liquid muscle tissue-equivalent phantom, as well as comparison of ‘treatment-planning’ simulations of several possible array SAR patterns with measured SAR from non-coherently driven spiral array antennae. Results : The applicator demonstrates a reasonably low return loss over a large bandwidth and the ability to generate a very uniform heating pattern. Ability to adjust SAR contours spatially to fit specific shapes is also demonstrated. Conclusions : This device should prove a welcome addition to a currently limited set of superficial heating applicators to provide controllable heating of superficial tissue disease. [ABSTRACT FROM AUTHOR]

The effects of waterbolus dimensions and configuration on the effective field size (EFS) of the Lucite cone applicator (LCA) for superficial hyperthermia are presented. The goal of the research is to develop guidelines which mark out a sub-set of optimal LCA-waterbolus set-ups. The effects of variations in (i) waterbolus thickness, (ii) waterbolus area, (iii) waterbolus length/width ratio and (iv) eccentric placement of the applicator have been investigated in an FDTD model study. The prominent effects are verified with IR thermography measurements. An optimal EFS value of 80?cm 2 is found for waterbolus area of 200–400?cm 2 . A small (10?×?10?cm 2 ) waterbolus area restricts the EFS to 25% of the optimal value. The sensitivity to sub-optimal waterbolus area and length/width ratio increases with waterbolus height. Eccentric placement of the LCA near the waterbolus edge reduces the EFS to up to 50% of the optimal value. The IR measurements confirm the model findings. Based on the results, the following guidelines for the clinical application of the LCA have been defined: the waterbolus (i) should extend the LCA aperture at least 2.5?cm, especially at the Lucite windows, and (ii) the height should not exceed 2?cm. [ABSTRACT FROM AUTHOR]