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H Sack

Publications and source records attributed to H Sack.

At least 109 records · Page 6Linked to original sources
PubMed1990

[Development and dosimetry of a 125 iodine applicator for brachytherapy of intraocular tumors].

Due to the low gamma energy (27-35 ke V), iodine 125 is especially suitable for brachytherapy of intraocular tumors. 125I is available as encapsulated seeds. Applicators can be individually loaded with these seeds to accommodate the shape of the tumor as much as possible. To measure the depth-dose distribution LiF thermoluminence detectors (TLDs, 1 mm3) are embedded in an RW-1 eye phantom at various distances and directions from the high active plaque positioned at the top of the phantom. To obtain the three-dimensional dose distribution, the TLDs are read after exposure for the appropriate time period. Based on experimental measurements of the 125I plaque, a computer program is developed to calculate the dose distribution within the eye and the radiation time for intraocular tumors. These results are very similar to those obtained when using mathematical equations published in the literature. In summary, three-dimensional dose distribution at various distances from an 125I eye plaque has been experimentally determined using a new method. This is an important prerequisite for introducing 125I plaques into the treatment of intraocular tumors.

Brachytherapy↗
PubMed1990

[Neutron flow measurements in the d(14) + Be neutron radiation field from the cyclotron in Essen].

It exists the possibility in the neutron therapy of specific tumours to increase the local energy dose in the tumour by treatment with fast neutrons under use of B-10. Thermal neutrons cause the neutron capture reaction B-10(n, alpha)Li-7 in tissue. A sufficiently high number of thermic neutrons is necessary combined with a possibly selective concentration of B-10 in the tumour as target volume for the clinical application. Gold foils were activated in a water phantom at several depths for the quantitative determination of the thermal neutron fluence. A result of this measurements is a maximal thermal neutron fluence of 1.44 X 10(10) cm-2 at depth of 5 cm with applied total energy dose of 0.8 Gy.

Fast Neutrons↗
PubMed1989

Carcinoma of the nasopharynx--comparison of the UICC and Ho clinical staging systems.

From 1974 to 1985 definitive radiation therapy was performed in 76 patients with nasopharyngeal carcinoma (NPC). Of the 76 patients 59 presented UICC stage IV and 13 UICC stage III. The distribution of the stages was more homogeneous for the Ho system: Ho I, n = 4; II, n = 21; III, n = 16; IV, n = 32; V, n = 3. Radiotherapy followed the guidelines of the M.D. Anderson Hospital in Houston. A median dose of 68 Gy was given to the primary and of 66 Gy to the neck nodes, independent of the histologic subtype. The 5-year actuarial survival rate was 41% and the disease specific relapse-free survival (r.f.s.) 45%. Analysis according to the UICC classification and Ho's classification showed obvious deficiencies in both staging systems, but did not result in major prognostic differences. The freedom from local relapses correlated (P less than 0.05) with the T categories of the UICC at presentation (75% in T1 vs 45% in T4) and the freedom from distant metastases was significantly influenced by the cervical status (fixed cervical lymph nodes (UICC N3) vs, e.g., UICC N2: 51% vs 90%; P less than 0.05). In case of supraclavicular lymph nodes (Ho IV; Kyoto C) the freedom of distant metastases was lower than in case of upper cervical lymph nodes (58% and 79%, respectively; P = 0.3).

Adolescent↗
PubMed1989

[Preoperative irradiation before enucleation in malignant melanoma of the uvea. Review of the literature and initial personal experiences].

The results of animal experiments and clinical studies concerning preoperative radiation of malignant extraocular tumors suggest that pre-enucleation radiation may be helpful in reducing the incidence of tumor-related death after enucleation of an eye containing a melanoma. Based on a retrospective study of 80 patients with malignant melanomas of the choroid or ciliary body, in which pre-enucleation irradiation with 8.5 Gray or 20 Gray was performed, no beneficial effect could be found in terms of better survival. The need for a prospective, randomized and possibly multicentered study is emphasized.

Adolescent↗
PubMed1989

[Dosimetry of ruthenium applicators with an eye phantom and small volume thermoluminescence detectors].

Even though 106Ru/106Rh applicators have been in clinical use over more than two decades for the radiotherapy of malignant uveal melanomas, the dosimetry of emitted beta radiation is still a physical problem. The dose rate at the applicator surface and the depth dose in tissue equivalent material can be determined only within +/- 30% error. Using new cubic-shaped thermoluminescence detectors (TLD) with small volume the dose distribution is examined in water equivalent material (RW-1). The spatial resolution is 14 times better compared to the previous technique. From dose measurements in an eye phantom the homogeneity of nuclide deposition and the depth dose distribution of a 106Ru/106Rh applicator are determined.

Brachytherapy↗
PubMed1989

Neutron therapy of low grade "pencil" gliomas of the spinal cord: a review of ten cases.

Between 1980 and 1986 ten patients (two males, eight females, median age: 35 years) with spongioblastomas and ependymomas grade I of the spinal cord were treated with fast neutrons from the d(14) + Be reaction after incomplete tumour surgery. Eight patients received three weekly fractions of 0.7 to 1.33 Gy and two patients four weekly fractions of 0.8 Gy to total doses of 7.4 to 10.4 Gy. Two complete and six partial remissions of ataxia and motor disturbances were observed. Bladder dysfunctions in five patients cleared up partially in three cases. In two patients the symptomatology remained unchanged. After a follow-up of eight to 88 months two initially complete and two out of six partial remission were maintained. No severe late effects of the skin have been determined. In summary it is concluded that for incompletely resected "pencil"-gliomas fast neutron therapy seems to be a feasible treatment modality.

Adult↗
PubMed1989

[Radiotherapy technics and results in nasopharyngeal carcinoma at the Cologne University Clinics from 1974 to 1985].

At the university clinics of Cologne 76 patients were treated for nasopharyngeal carcinoma with curative intent from 1974 to 1985. The radiotherapy followed the guidelines of the M.D. Anderson Hospital, Houston and the Royal Marsden Hospital, London using a multiple field technique. A median dose of 68 Gy megavoltage radiotherapy was given to the primary and of 66 Gy to the neck nodes independent of the histologic subtype. The determinate relapse-free survival was 45% after five years and the local relapse-free survival 61%. The multiple field technique allowed to reduce the dose to the parotid. Only 25% of the patients suffered from a dry mouth after one year and only 10% after four years.

Adolescent↗
PubMed1988

[Breast carcinoma in men: radiotherapy and treatment results].

The treatment of 34 men with stage T1 N0 M0 to T3/4 N1 M0 mammary carcinomas was followed by a five-year survival rate of 70%. Three patients suffering from initial remote metastases died after 2 to 3.5 years. The probability of a five-year survival decreases with increasing tumor growth and axillary involvement. The prognostic effect of receptor state and grading could not be investigated in our patients. Our own data as well as recent data from literature suggest that, with respect to TNM stages in mammary carcinoma, there is no prognostic difference between men and women. It is not very clear at present if postoperative irradiation exerts a favorable influence on the survival rate. However, it reduces the local recurrence risk for men and women. 45 Gy in five weeks should be considered as a minimum dose. The indications for postoperative irradiation are discussed.

Adenocarcinoma↗
PubMed1988

[The knowledge of cancer patients about their disease].

160 patients suffering from malignant tumors were interviewed by means of a questionnaire. Most of them had been treated by radiotherapy in a curative intent. The treatment had been finished about one year before, all patients submitted to curative therapy were free from recurrences. 80% out of them knew about their diseases, benignity or malignancy, sites of the primary tumors, and extent of lymph node metastases. Only 5% of the patients had to be informed about their disease at the Radio-oncology Hospital, 88% had been informed already by the physicians before. About 90% of the patients were of the opinion that a complete information was suitable and desired by them. As our patients got older, their desire for information diminished considerably. Even one year after the end of their disease, 34% did not speak frankly with other persons about their disease. The study showed furthermore that the hope of being cured is not affected by information. In this context, 90% of the patients were of the opinion that information should not exceed a certain degree.

Adolescent↗