Comments on "Investigation of Histology Region Dielectric Measurements of Heterogeneous Tissues".

In the paper, "Investigation of histology region in dielectric measurements of heterogeneous tissues," by Porter and O'Halloran, the authors utilize a flexible phantom in a layered material dielectric property analysis to quantify the effective sensing volume of a coaxial dielectric probe. Ostensibly, this test has been used by others to characterize the region for which percent variation in the material composition in front of the probe corresponds to percent variation in the computed effective dielectric properties. By employing a compressible material, the authors fail to isolate features that are attributable solely to the probe, itself, and inadvertently incorporate confounding characteristics associated with the compressible nature of the material.

A photographic technique for quick assessment of mechanical isocenter of a linear accelerator.

Demands for mechanical accuracy of medical linear accelerators are increased due to the stereotactic and modulated rotational treatments. Mechanical inaccuracies affect the size and shape of the mechanical and radiation isocenters. In practice, the mechanical isocenter is defined by the intersection of rotational axes.

Open-Ended Coaxial Dielectric Probe Effective Penetration Depth Determination.

We have performed a series of experiments which demonstrate the effect of open-ended coaxial diameter on the depth of penetration. We used a two layer configuration of a liquid and movable cylindrical piece of either Teflon or acrylic. The technique accurately demonstrates the depth in a sample for which a given probe diameter provides a reasonable measure of the bulk dielectric properties for a heterogeneous volume.

Experimental and Analytical Comparisons of Tissue Dielectric Constant (TDC) and Bioimpedance Spectroscopy (BIS) in Assessment of Early Arm Lymphedema in Breast Cancer Patients after Axillary Surgery and Radiotherapy.

Background: Early diagnosis of breast cancer treatment-related lymphedema (BCRL) is of great importance for longstanding treatment results. Tissue dielectric constant (TDC) and bioimpedance spectroscopy (BIS) both have a potential for early diagnosis, but have not been compared.

Methods And Results: One hundred women, treated for breast cancer with breast surgery, axillary dissection, and radiotherapy, were examined within one year after breast cancer treatment, as part of the follow-up procedure.

Tangential volumetric modulated arc therapy technique for left-sided breast cancer radiotherapy.

Background: The aim of the present study was to introduce a new restricted tangential volumetric modulated arc therapy (tVMAT) technique for whole breast irradiation and compare its dosimetric properties to other currently used breast cancer radiotherapy techniques.

Method: Ten consecutive women with left-sided breast cancer were enrolled in this retrospective study. Four treatment plans were generated for each patient: 1) standard tangential field-in-field (FinF), 2) tangential intensity modulated radiotherapy (tIMRT), 3) tangential VMAT (tVMAT) with two dual arcs of 50-60° and 4) continuous VMAT (cVMAT) with a dual arc of 240°.

Role of microRNAs and DNA Methyltransferases in Transmitting Induced Genomic Instability between Cell Generations.

There is limited understanding of how radiation or chemicals induce genomic instability, and how the instability is epigenetically transmitted to the progeny of exposed cells or organisms. Here, we measured the expression of microRNAs (miRNAs) and DNA methyltransferases (DNMTs) in murine embryonal fibroblasts exposed to ionizing radiation or 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), which were previously shown to induce genomic instability in this cell line. Cadmium was used as a reference agent that does not induce genomic instability in our experimental model.

Dose- and time-dependent changes of micronucleus frequency and gene expression in the progeny of irradiated cells: two components in radiation-induced genomic instability?

Murine embryonic C3H/10T½ fibroblasts were exposed to X-rays at doses of 0.2, 0.5, 1, 2 or 5 Gy.

Radiation-induced genomic instability in Caenorhabditis elegans.

Radiation-induced genomic instability has been well documented, particularly in vitro. However, the understanding of its mechanisms and their consequences in vivo is still limited. In this study, Caenorhabditis elegans (C.

Does the outcome of prostate cancer patients with large prostates differ from small prostate size in permanent seed, low dose-rate brachytherapy?

Objective: Brachytherapy has good results in the treatment of early prostate cancer (PC). The procedure is challenging in large prostates, and the optimal prostate volume for brachytherapy was previously defined as ≤40 ml. This study analysed the outcome of PC patients with small (group A) and large (group B) prostate volume in prospective data.

Interactive multiobjective optimization for anatomy-based three-dimensional HDR brachytherapy.

In this paper, we present an anatomy-based three-dimensional dose optimization approach for HDR brachytherapy using interactive multiobjective optimization (IMOO). In brachytherapy, the goals are to irradiate a tumor without causing damage to healthy tissue. These goals are often conflicting, i.

Eight years experience of local prostate cancer treatment with permanent I125 seed brachytherapy--morbidity and outcome results.

Background And Purpose: There are only a limited number of reports of treatment of prostate cancer with permanent prostate seed I(125) brachytherapy (PPB) in Europe. We describe results from one Finnish institution having treated 444 patients with a follow-up of eight years.

Material And Methods: Morbidity was evaluated by International Prostate Symptom Score and International Index of Erectile Function questionnaires.

Comparison of conventional inserts and an add-on electron MLC for chest wall irradiation of left-sided breast cancer.

Background: Collimation of irregularly shaped clinical electron beams is currently based on electron inserts made of low melting point alloys. The present investigation compares a conventional electron applicator with insert and add-on eMLC-based dose distributions in the postoperative chest wall irradiation of left-sided breast cancer.

Material And Methods: Voxel Monte Carlo++ (VMC++) calculated dose distributions related to electron fields were compared with 10 left-sided breast cancer patients after radical mastectomy.

Major reduction of monitor units with the avoidance of leaf-sequencing step by direct aperture based IMRT optimisation.

Background And Purpose: Compared with conventional 3D conformal radiotherapy (3D-CRT) the use of intensity-modulated radiation therapy (IMRT) has increased monitor units (MUs) in the delivery of prescribed dose to the patient and thus a potential risk of radiation-induced secondary cancer. Due to the elimination of the leaf-sequencing step in direct aperture based IMRT optimisation (DABO) the MUs in the beam delivery can be reduced. We compared MUs calculated by DABO with other IMRT techniques and 3D-CRT.

Reliability and validity of a bioimpedance measurement device in the assessment of UVR damage to the skin.

Ultraviolet radiation (UVR) is the primary cause of skin cancers. However, it is difficult to evaluate the amount of UVR absorbed into the skin retrospectively. Therefore, objective and non-invasive quantitative method would be valuable for epidemiological UVR exposure assessment.

Dielectric measurement in experimental burns: a new tool for burn depth determination?

Background: There has been a lack of methods to provide quantitative information of local tissue edema after burn injury. Noninvasive dielectric measurements provide this information. The measured value, the dielectric constant, is directly related to the amount of water in tissue.

Radiation-induced changes in skin type I and III collagen synthesis during and after conventionally fractionated radiotherapy.

Background And Purpose: To measure local changes of collagen metabolism in irradiated breast skin and systemic changes in serum during and after radiotherapy and correlate these changes with skin thickness, erythema and palpable subcutaneous induration.

Patients And Methods: Aminoterminal propeptides of type I and type III procollagens (PINP and PIIINP, respectively) were measured from skin suction blister fluid (SBF) in 21 breast cancer patients with breast conserving surgery and conventionally fractionated radiotherapy (RT) to a total dose of 50Gy. Suction blisters were induced in the operated and contralateral breast skin before RT, at 2.

Measurement of hydration in the stratum corneum with the MoistureMeter and comparison with the Corneometer.

Background/purpose: MoistureMeter is a novel capacitive device for measuring the hydration of stratum corneum (SC). The capacitor 'plates' are formed by the probe material and the well-conducting epidermal-dermal skin layers, while the dry layer of SC acts as an 'insulator' of the capacitor. Due to this measurement principle, the measurement depth is not constant, but equal to the thickness of the dry layer of SC.

Dielectric constant of skin and subcutaneous fat to assess fluid changes after cardiac surgery.

The ability to objectively determine the degree of tissue edema and to monitor on-line fluid balance in critically ill patients would be a clinical benefit. In this prospective descriptive trial, we evaluated a new noninvasive method--dielectric constant of skin and subcutaneous fat (SSF)--in assessing fluid balance during cardiac surgery. The dielectric constant at the applied high radiofrequency is a direct measure of tissue water content.

A closed unventilated chamber for the measurement of transepidermal water loss.

Background/aims: Open chamber systems for measuring transepidermal water loss (TEWL) have limitations related to ambient and body-induced airflows near the probe, probe size, measurement sites and angles, and measurement range. The aim of the present investigation was to develop a closed chamber system for the TEWL measurement without significant blocking of normal evaporation through the skin. Additionally, in order to use the evaporimeter to measure evaporation rates through other biological and non-biological specimens and in the field applications, a small portable, battery-operated device was a design criteria.