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Biomedical subjects

K Schnabel

Publications and source records attributed to K Schnabel.

At least 91 records · Page 5Linked to original sources
PubMed1987

[Treatment of radiation pneumonitis with curative intent--a review].

Therapeutic assays with medicaments intended for the healing of radiopneumonitis have a long tradition. Numerous medicaments have been assayed in men and animals during the last thirty years without having reached any lasting positive results. In the end, the fibrotic stage of this radiogenic side effect has always been refractory. It was, however, possible with some medicaments to relieve the symptoms of the early exudative phase. This study is supposed to give a general survey of the present state of knowledge in this field.

Animals↗
PubMed1986

[Irradiation of grades III and IV astrocytomas with new types of radiation].

Until 1983, more than 300 astrocytomas of degree III and IV have been irradiated all over the world with new types of radiation such as neutrons, protons, alpha particles, heavy ions, and pions. Up to now a therapeutic progress could not be achieved. Radiobiologic experimentations suggest that the dense ionisation is unfavorable in the irradiation of malignant cerebral tumors. The clinical radiotherapy research with protons should therefore be intensified and hyperfractionation should be critically reviewed.

Alpha Particles↗
PubMed1986

[Chest wall moulages for radiotherapy of resected breast cancer with fast electrons: comparative tests of different materials].

Irradiation of the thoracic wall with high-speed electrons is one of the standard methods of prophylaxis and therapy of local recurrences and cutaneous metastases of an operated mammary carcinoma. The surface dose, however, is only 85% of the maximum dose, due to the depth dose curve of the electron beams with the preponderantly applied energy of 7MeV. This is a poor value, since most of all recurrences appear near to the surface and so the risk of giving an insufficient dose is involved. The dose distribution could be essentially improved by the use of moulages on the chest. These moulages were made of different materials which were tested and compared with respect to their suitability for radiotherapeutic purposes. The best materials proved to be "Urgo-Plastan" (manufacturer: Holphar, Sulzbach) and "Orthoplast" (manufacturer: Johnson & Johnson, Düsseldorf). Both materials are synthetic substances which after heating can easily be adapted to the body shape and which offer a good stability, little inconvenience for the patient and a relative easy handling. With these moulage materials, the surface dose is increased to 98% ("Urgo-Plastan") and 99% ("Orthoplast") of the maximum dose.

Breast Neoplasms↗
PubMed1986

[Face masks for radiotherapy of head and neck tumors: comparative tests of different materials].

A most precise immobilisation of the patient's head is indispensable in order to reach a high degree of exactness and reproducibility in radiotherapy of malignant head and neck tumors. Face masks made of different synthetic materials have proved to be a simple and economical solution for this problem. Based on our own experiences with "Baycast Longuettes" (manufacturing firm: Johnson & Johnson, Düsseldorf), eleven substances have been tested in the phantom (compound of plaster and synthetic resin, thermoplast, polyurethane foam, compounds of cotton and synthetic resin, and fibre glass compounds). An appropriate material was "Hexcelite" (manufacturing firm: Medimex, Hamburg), a reticulated thermoplast which after warming up can be easily adapted to the patient's face and which guarantees a very good fixation of the head. As compared to solid masks, there is only a slight superposition of the depth dose of Co-60 gamma radiation by secondary electrons from the mask material, so that an increased rate of radiogenic dermatitides is not to be expected.

Casts, Surgical↗
PubMed1985

[Radiotherapy of paraplegia caused by extramedullary hematopoietic tissue].

The presentation by computed tomography of an extramedullar epidural intraspinal hemopoisis has only been described sporadically. It has been possible to visualize by CT-scans the regression under radiotherapy of a sensory and motor paraplegia in a 17 years old patient with beta-thalassemia major. The central nervous system (thoracic and lumbar zone as well as os sacrum) was exposed to a total reference dose of 30 Gy which was administered within twenty days by a 60Co unit in single doses of 2 Gy each. From 4 Gy on, the paraplegic symptoms regressed continuously. The control CT taken after 26 Gy- the paraplegia had completely disappeared at this time-showed a significant regression of the intraspinal soft tissue masses. Radiotherapy is very important in the treatment of this disease. A direct correlation is found between clinical symptoms and CT-presentation.

Adolescent↗
PubMed1985

[Experience in the use of face masks for radiotherapy of head and neck tumors].

By means of positioning and fixation aids, the precision and reproducibility of irradiation fields in radiotherapy of malignant tumors of the head and neck can be considerably improved. Face masks made of different synthetic materials have proved to be a practicable solution of this problem. In our hospital we have developed and tested a simple and not expensive possibility of manufacturing the masks with "Baycast" (producer: Bayer AG Leverkusen). The material is generally well tolerated by the patients, and the head is sufficiently fixed. An increased incidence of radiogenic dermatitides is caused by the overlapping of the depth dose of the Co-60 gamma radiation due to additional secondary electrons emanating from the mask material. This effect can be partly prevented by cutting out the irradiation fields in the masks.

Cobalt Radioisotopes↗
PubMed1984

Radiotherapy of soft tissue sarcomas with neutrons or a neutron boost.

A cooperative trial of neutron therapy for soft tissue sarcomas was started in 1978. 112 unselected and not previously irradiated patients (62% T3 tumours, 35% recurrent tumours) were treated up to June 1982 with neutrons alone. An analysis of these cases with a mean follow-up period of 22 months (range 12 to 45 months) is given in this report. Very preliminary results are presented for 60 patients treated with a neutron boost only. These showed a substantially lower complication rate. The major results of this phase II trial are: The survival rate of 3.5 years was strongly dependent on the stage of the tumour; for 8 patients with T1 tumours it was 100%, for 35 patients with T2 tumours, 77%, and for 69 patients with T3 tumours, 45%. The survival rate at 3.5 years was strongly dependent on surgery before the beginning of radiotherapy; for 54 patients after surgery without clinical evidence of residual tumour it was 73%, for 58 patients with inoperable primary or recurrent tumour, 47%. The survival rate of 31 patients with recurrence after neutron therapy was only 36%. The overall rate of serious complications was 28.6% after neutron therapy, but only 5% after neutron boost therapy (mean follow-up period: 12 months, range 5 to 48 months).

Follow-Up Studies↗
PubMed1984

[CT volumetry of intrathoracic space-occupying processes].

Preoperative CT volumetry was performed in 39 patients with intrathoracic neoplasms. The results are compared to postoperative volume measures of the surgical preparation. The correlation of both measuring series was very high (p = .94). The estimated influence of systematic and stochastic errors was only 10 to 15%. The authors outline the consequences for clinical practice: by means of the better quantification in the T category of the TNM system, the surgeon is in a position to make a more precise preoperative planning. The reliable numeric in vivo determination of regression and growth velocity of tumors and/or metastases allows for the first time an exact quantification of control examinations during and after radiotherapy or chemotherapy. This will possibly lead to a more precise individual prognosis. In experimental radiotherapy a more detailed description of the evolution of experimental tumors in the living animal will be possible by this procedure.

Humans↗
PubMed1984

[Significance of radiotherapy for the treatment of primary bone and soft tissue sarcomas].

Recent data from the literature as well as our own treatment results of soft tissue sarcomas and primary bone tumours with the exception of osteosarcomas indicate, that: 1. A conservative, limb sparing therapy should be attempted in peripheral bone tumours and soft tissue sarcomas. This may be achieved in 85% to 97%. 2. The recurrence rate is in a range of 3% to 22%, which does not exceed the results of ablative surgery. 80% of possible recurrences can be controlled by consecutive surgery. 3. After the development of improved treatment techniques, the complication rate is less than 10%. 4. Conservative limb sparing treatment does not decrease the survival rate. However, these results are not derived from randomised studies. 5. Apart from osteosarcomas and Ewing sarcomas adjuvant chemotherapy is recommended for G3 tumours. The time interval for evidence of metastases may be doubled by this treatment modality. 6. There is some evidence that neutron-boost therapy may improve local control rates in T2 and T3 soft tissue sarcomas.

Bone Neoplasms↗
PubMed1983

Neutron and neutron-boost irradiation of soft tissue sarcomas: a 4.5 year analysis of 139 patients.

A 4.5 year analysis of neutron and neutron-boost therapy is presented for 139 patients with soft tissue sarcomas. The actuarial survival rate of all patients is 64.3%, the disease-free survival rate is 61.6%. Significant differences in local control rates were found as a function of tumour stage (100% for T1, 72% for T2 and 46% for T3; p: 0.018) and as a function of the presence (50.5%) or absence of clinical evidence of tumour at the time of irradiation (76%; p: 0.002). The corresponding actuarial survival rates are 90.1% for T1 tumours, 78.5% for T2 tumours and 51.2% for T3 tumours, and on the other hand, 50.5% for patients with gross tumour and 76% for patients with no clinical evidence of tumour. A rather high morbidity rate (31/111, i.e. 28%) was observed after full neutron treatment. In order to reduce this complication rate, a combination of photons and a neutron boost was adopted. On 28 patients treated up to now, only two severe complications were observed. The effectiveness of this treatment regimen is presently being evaluated in a prospective European Organization for Research on Treatment of Cancer (EORTC) trial.

Adolescent↗
PubMed1983

[Comparison of clinical methods for the demonstration of radiation-induced lung changes. Experimental study on animals].

The purpose of this study was to compare the value of different imaging methods (radiography, computer tomography and scintigraphy) for demonstrating pulmonary fibrosis or radiation pneumonitis. The right lungs of 50 rabbits were irradiated with 3200 to 6200 rd. The lung changes were observed by the above methods over a period of 13 weeks. Histological examination served as the basis for evaluating the imaging methods. The comparison demonstrated the superiority of computer tomography when density measurements were included in the diagnostic criteria. The accuracy was about 95%. Scintigraphy was inferior to computer tomography as a quantitative method, using differences in the counts per unit area. Radiology as a subjective method achieved an accuracy of about 84%, approximately the same as scintigraphy.

Animals↗
PubMed1983

[Significance of radiotherapy in the treatment of soft tissue sarcomas].

Postoperative photon- or electron irradiation has been well established in the treatment of soft tissue sarcomas. For further improvement of these results, neutron- or neutron-boost irradiation was introduced at several centres of radiation therapy. In this report, the 3.5 year results of 112 patients are analysed. The majority (62%) had T3-tumours (UICC classification, Geneva 1978). 58 patients presented with gross tumour at the beginning of radiotherapy, and 54 patients without clinical evidence of tumour. 39 patients (35%) had recurrent tumours. A highly statistical difference in local tumour control was found between the group of patients with gross tumour (47%) and the group of patients without clinical evidence of tumour (81%). A statistical difference in local control and survival was also found between the group of patients with T1-tumours (100%), T2 tumours (76.8%) and T3 tumours (44.5%), whereas no differences were found in terms of grading. The high complication rate of 25%, which was found after neutron therapy, was reduced to 7% after introduction of a neutron boost. The statistical significance of this treatment modality is presently being evaluated in a randomised EORTC trial. Adjuvant chemotherapy is recommended für all G3 tumours.

Adolescent↗
PubMed1983

[Comparison of neutron and photon irradiation of bronchial carcinoma].

Fast neutrons are only superior to photons if their relative biologic effectiveness (RBE) is higher within the tumor than in sound organs. It was therefore the object of this study to test the effects and side effects of rapid neutrons in an especially appropriate tumor model. The bronchial carcinoma was chosen because, according to radiobiologic experiences, the relative biologic effectiveness of neutrons is significantly higher in the Lewis bronchial carcinoma than in the normal lung. These experiences showed furthermore that, compared to other organs, the lung is relatively unsensitive to neutrons, so that the conditions for a treatment with this new type of radiation are favorable. Despite these favorable conditions, no local superiority of neutrons with respect to photons could be established by a clinical study including 115 cases. It shall be examined in a further study if a therapeutic advantage can be realized by a combination of neutrons and photons.

Carcinoma, Bronchogenic↗
PubMed1983

[Radiation side effects of neutron and photon therapy of soft tissue sarcomas. Results of a 4-year pilot study].

Within the frame of a four-year pilot study, 41 soft tissue sarcomas were treated with neutrons (31 patients), photons (3 patients), or a combination of both radiations (7 patients). All three patients submitted to relatively high neutrons doses (N + gamma) of 19 Gy showed marked radiogenic side effects. A relatively high percentage of radiogenic side effects (4/11) was observed after a total dose of 18 Gy, too. However, doses of 16 to 17 Gy did not cause any severe troubles. After doses below 16 Gy, the local recurrence rate is relatively high.

Humans↗
PubMed1983

[Fractionated irradiations of the normal rabbit lung with fast neutrons or photons].

115 rabbits were irradiated with our usual fractionation scheme, and the dose effect curves for fast neutrons and photons (60Co) were determined with respect to pneumonitis and pulmonary fibrosis, respectively. On comparison of the radiogenic alterations three months after therapy, the relative biological effectiveness calculated by means of these dose effect curves was 2,9 for the fast neutrons. Furthermore, the authors tested the conformity of some clinical examination methods such as X-ray, scintigraphy and computed tomography with histological findings of pneumonitis and pulmonary fibrosis, respectively. In this regard, computed tomography was superior to the other examination methods.

Animals↗