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Biomedical subjects

W Straube

Publications and source records attributed to W Straube.

161 records · Page 9Linked to original sources
PubMedDate not supplied

Interstitial thermoradiotherapy in treatment of malignant tumours.

From October 1981 to October 1985, 48 recurrent/persistent tumours (46 patients) were treated with a combination of interstitial hyperthermia and interstitial radiation therapy. All patients had failed other conventional treatment modalities. Radiation was administered using 192Ir with doses varying from 2000 to 6000 rad, depending on the dose of previous irradiation. Hyperthermia was administered with either localized current fields (LCF) or microwaves, two sessions each, minimum tumour temperature of 42.5 degrees C for 60 min. Of 37 lesions treated with at least one satisfactory hyperthermia session, there were 26 of 37 (70 per cent) complete responses and 11 of 37 (29.7 per cent) partial responses. Of 11 lesions with no sessions of satisfactory hyperthermia, there were no complete responses and only five partial responses. The detailed results are presented.

Adult↗
PubMedDate not supplied

Thermoradiotherapy of malignant melanoma.

From 1978 through February 1986, 49 measurable lesions in 18 patients with recurrent primary or metastatic malignant melanomas were treated with a combination of radiation therapy and hyperthermia. The primary sites were head and neck (eight), chest wall (two), pelvis (one), upper extremities (three), and lower extremities (35). Because of the length of the study, the dose and fractionation of radiation therapy varied (dose per fraction from less than 400 cGy to 800 cGy and a total dose of 2000 cGy to 6000 cGy). This variation was mostly dependent on the prior course of radiation therapy of these lesions. The hyperthermia technique used in these patients was superficial local microwave hyperthermia; a minority of patients were treated with ultrasound. Complete response was achieved in 29 lesions (59.2 per cent) and partial response in six lesions (12 per cent). In a separate analysis of 67 lesions with superficial malignant melanoma who were treated by radiation therapy alone, a 24 per cent complete response and a 34 per cent partial response were achieved. Detailed analyses are presented in regard to dose per fraction, total radiation dose, and the size of lesions.

Combined Modality Therapy↗
PubMedDate not supplied

Physical predictors of adequate hyperthermia with the annular phased array.

One hundred and fifty-two hyperthermia sessions in 36 consecutive patients treated with the BSD 1000 annular phased array system (APAS) are reviewed with regard to physical predictors of quality of hyperthermia. Although central tumour temperatures exceeding 42 degrees C were momentarily obtained in 62% of the sessions, it frequently proved difficult to maintain the patient at temperature for prolonged periods of time. The time to reach target temperature was negatively associated with quality of hyperthermia. Thus, of 25 sessions which required over 25 min to attain a temperature of 42 degrees C, only one was adequate (defined as central tumour temperature greater than or equal to 42 degrees C maintained for at least 30 min) as opposed to 28/69 adequate sessions when 42 degrees C was reached in less than 25 min. Physical parameters measured in the first 3 min of the session found to be associated with adequate hyperthermia include an initial rate of temperature rise at the tumour site exceeding 0.4 degrees C/min achieved with a net forward power less than 1500 W. Only three of 57 sessions not meeting these criteria were adequate. Treatment policy recommendations and recommendations for future research are made.

Abdominal Neoplasms↗
PubMedDate not supplied

Phantom studies and preliminary clinical experience with the BSD 2000.

The BSD 2000 system is an array of microwave antennas operating in the 60-120 MHz range. It is a four-quadrant regional hyperthermia device with phase control permitting the operator to choose the point of constructive interference. A computer preplanning system is provided. We have compared the computer predictions with measured relative specific absorption rate (SAR) distributions in muscle equivalent phantoms and pig cadaver. The predicted SAR distribution is in qualitative agreement with observation, although differences of approximately 3-5 cm in the location of iso- SAR contours were noted. The longitudinal dependence of relative of distance cephalad to the central plane of the power distribution was measured, and it was found that a length of 15-20 cm was covered by the 50% iso-SAR. SAR measurements in the spinal canal of a pig cadaver showed that, even at resonance frequency, the measured SAR in the cervical spine was small (0.07 of central axis SAR). However, the spinal canal SAR as measured in the central plane of an evenly balanced configuration was 0.6 of the peak SAR. Marked reduction of the spinal canal SAR could be obtained with steering techniques and was in good agreement with the computer preplan. This paper reviews preliminary clinical experience with 17 patients. All but 2 patients were treated with steering techniques to permit partial sparing of normal tissues. The goal of maintaining central tumour temperature at or above 42 degrees C for at least 30 min was maintained in 41 of 67 sessions (61%) and in at least one session for all but 2 patients. Seventy-seven per cent of monitored tumor points attained at least 42 degrees C in patients for whom thermal mapping was performed. Significant cardiovascular stress developed during hyperthermia in two patients. There have been five complete responses and seven partial responses in the 17 patients.

Combined Modality Therapy↗
PubMedDate not supplied

Equilibrium temperature distributions in uniform phantoms for superficial microwave applicators: implications for temperature-based standards of applicator adequacy.

Equilibrium temperature distributions are computed using measured SAR distributions for five different superficial microwave (915 MHz) applicators. We assume a model with uniform conduction and blood flow. A Green's function approach is used to calculate equilibrium solutions which identically obey boundary conditions at the surface of the phantom and at infinite depth. The equilibrium solutions are categorized by surface temperature (TS), maximum allowed temperature (TM), and by a parameter (referred to as the diffusion length, lambda) which characterizes the contributions of thermal conduction relative to blood flow. The computed equilibrium temperature distribution at depths of 2 and 3 cm is strongly dependent on lambda and on TM. It is not strongly dependent on surface temperature for TS below 35 degrees C. In previous work we compared the SAR distribution with local control of 53 superficial tumours with over 1 year of follow-up. As an alternative to an SAR-based description of applicator adequacy we consider a temperature-based standard. Tumours are categorized by the minimum value of lambda that would allow full coverage of the tumour volume by the 42 degrees C contour, assuming a TM of 47.5 degrees C and a TS of 35 degrees C. Eighteen of 27 lesions (67%) were locally controlled for lambda less than 1 cm. The local control in 26 lesions with lambda greater than or equal to 1 cm was 31% (p = 0.016). The lesions with the best results were those with both good coverage in theory (lambda less than 1 cm) and with all monitored catheter tracks achieving at least one session with 30 min at or above 43 degrees C. We found that the temperature-based standard of applicator adequacy was not independent of an SAR-based standard, and in this cohort of patients either a minimum SAR criterion or a maximum diffusion length criterion would serve equally well as a screen for inappropriate applicators.

Body Temperature↗
PubMedDate not supplied

Is the tumor marker CASA dependent on the menstrual cycle?

The time course and characteristics of the tumor marker CASA (Cancer Associated Serum Antigen) during the menstrual cycle were analysed. We investigated whether hormonal influences in women and the score of this tumor marker ought to be considered in diagnosis. It could be demonstrated that CASA is not influenced by physiological alterations of the hormonal status in regularly ovulating women.

Adult↗
PubMedDate not supplied

First experiences with the use of CASA in mammary carcinoma.

The expression of the tumor marker CASA (cancer associated serum antigen) was studied in patients with mammary carcinoma; increased values were almost exclusively seen in cases of manifest metastasis. No correlation existed between tumor stage, lymph node involvement and grading. Marker levels were tested by means of enzyme-immune-assay of the firm medac (Hamburg), with a cut-off value set at 4 U/ml.

Biomarkers, Tumor↗