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Biomedical subjects

H Leitner

Publications and source records attributed to H Leitner.

At least 37 records · Page 2Linked to original sources
PubMed1992

Hyperfractionated radiotherapy and polychemotherapy in brain stem tumors in children.

Between October 1989 and January 1991 five children with brain stem tumors were treated with sequential chemo- and radiotherapy. The polychemotherapy consisted of procarbazine, ifosfamide, etoposide, methotrexate, cisplatin and cytosine arabinoside. Locally, hyperfractionated radiotherapy was delivered at a total dose of 63.8 Gy (1.1 Gy twice daily, 10 fractions per week). After a median observation time of 11.8 (range 4-23) months from diagnosis three children are alive and without evidence of tumor progression. Two patients died from tumor progression 11 and 16 months respectively after initiation of therapy.

Adolescent↗
PubMed1992

[Metallic mesh endoprosthesis and intraluminal high dose rate 192Ir brachytherapy in the palliative treatment of malignant bile duct obstruction. Initial results].

Since December 1989, 9 patients with inoperable malignant biliary tract obstruction were treated palliatively by a combined modality treatment consisting of placement of a permanent biliary endoprosthesis followed by intraluminal high dose-rate 192Ir brachytherapy. A dose of 10 Gy was delivered in a hyperfractionated schedule at the point of reference in a distance of 7.5 mm of centre of the source. External small field radiotherapy (50.4 Gy, 1.8 Gy per day, 5 fractions per week) was also given in six cases (M/O, Karnofsky greater than 60%). In 9/9 cases an unrestrained bile flow and an interruption of pruritus was achieved, in 78% (7/9) of cases the duration of palliation was as long as the survival time (median survival time 7.5 months).

Adenocarcinoma↗
PubMed1991

[Tensile strength of the stapes footplate. Pressure-induced inner ear damage in operated ears caused by TORP prostheses?].

In a recent textbook concerning ear surgery, it is recommended to put some connective tissue on the stapes footplate before introducing a TORP. This should avoid penetration of the shaft of the TORP into the inner ear. Experimental studies were performed to estimate the pressure needed for pushing a TORP through the footplate. We found those pressures to be much higher than those which might occur by increasing pressure in the external ear canal or decreasing pressure in the middle ear. This means that perforations of the footplate are not due to one big event of changing pressure, but rather by chronic irritations or foreign body reactions. Anyhow, we consider the protection of the footplate by a layer of connective tissue to be very useful.

Ear, Middle↗
PubMed1991

[Optimizing target volume assessment in irradiation of intraocular melanomas with ruthenium applicators].

Radioactive applicators have been used for conservative therapy of melanomas in the vicinity of the nervus opticus and of melanomas of the ciliary body for a few years. The aim of optimal radiotherapy is to destroy all tumor cells and to protect the optic nerve and macula. Therefore, we calculated the dose distributions and isodoses for ruthenium applicators. Isodoses show underdosage or overdosage in the tumor area. We also present a calculation model with which it is possible to simulate selective shielding of activated parts of the applicator.

Brachytherapy↗
PubMed1991

[Evaluation of irradiation techniques in breast carcinoma using dose-volume histograms. Comparison of the heart and lung exposure].

For irradiation of the internal mammary lymph nodes (IMN), together with irradiation of the breast the commonly used treatment techniques are of three types: 1. two tangential opposed fields, 2. three field plans with a separate "straight on" IMN-field, or 3. with a separate "angled" IMN-field. To determine lung and heart volumes and doses for these techniques, dose-volume-histograms in 30 patients were analyzed. The optimum dose distribution was achieved with the "angled" field technique and an appropriate combination of electrons and 60Co gamma radiation for the IMN-field. (The beam mixture used was 40% 60Co beam and 60% electron beam.) The least possible dose to the lung was obtained with the "straight-on" field technique and the least possible dose to the heart with the separate "angled" IMN-field technique.

Breast Neoplasms↗
PubMed1991

[Interstitial Ir-192 afterloading therapy with sequential warm-water hyperthermia].

For selective heating of superficially located or easily accessible tumors interstitial hyperthermia has become an increasing popular method in combination with interstitial radioactive implants. At our institution the hyperthermia treatment is performed utilizing the warm water system KHS-9, which is adapted to our Ir-192 high-dose-rate afterloading device, so that the same hollow needles for the interstitial radiation can be used for the heating procedure. So far, this technique has been applied for the treatment of primary and carcinomas, gynecological recurrences, and metastases of malignant melanomas after preceding in vitro measurements of temperature distribution. As a result both, in vitro and in vivo investigations showed good homogeneity of the temperature throughout the heated volume. Analysing the temperature data of in vivo measurements the maximum deviation of temperature was found to be 1.5 degrees C. When using a needle spacing of 8 mm, the temperature required for clinical application (42.5 degrees C) could be maintained in all heat treatments with a preselected water temperature of 46 degrees C to 49.5 degrees C.

Anus Neoplasms↗
PubMed1990

Radiation therapy in stage III ovarian cancer following surgery and chemotherapy: prognostic factors, patterns of relapse, and toxicity: a preliminary report.

Twenty patients with FIGO stage III epithelial ovarian cancer who had undergone maximum cytoreductive surgery (including pelvic and paraaortic lymph node dissection) and combination chemotherapy (4-10 cycles, median 6) were treated with irradiation to the abdomen and pelvis with 30 Gy followed by diaphragmatic/paraaortic and pelvis boost fields to 42 and 51.6 Gy, respectively. Second-look laparotomy was not performed. Seventeen of 20 patients completed the planned course of radiation. In 2 cases, failure to complete treatment was related to acute hematologic toxicity, and 1 patient refused further treatment. Five patients (29%) required treatment breaks ranging from 8 to 16 days (median, 12 days) due to pancytopenia. Actuarial overall survival and relapse-free survival at 3 years for the 17 patients who completed radiation was 69 and 47%, respectively, with follow-up ranging from 19 to 53 months (median: 24, mean: 27.6 months). Seven patients (41%) relapsed within the abdomen alone and 2 patients developed extraabdominal lymph node metastasis as their sole site of failure. The prognostic factors evaluated for correlation with relapse-free survival included histologic subtype, grade, amount of residual disease at the time of surgery, and nodal involvement; only residual tumor at surgery (none vs less than or equal to 2 cm or greater than 2 cm) was found to be statistically significant (P less than 0.01). Three-year overall survival correlated with amount of residual disease following the initial cytoreductive surgery. It was 100% for patients with no residual disease, 66.7% for less than or equal to 2 cm, and 26.7% for those with greater than 2 cm residual disease, respectively. Radiation treatment was well tolerated, with only one patient developing treatment-related bowel obstruction 7 months after radiation therapy. The results of this planned trimodality treatment approach compare favorably with those reported following surgery and chemotherapy, particularly in patients who have been maximally cytoreduced.

Adult↗
PubMed1990

Intraoperative plus external beam irradiation in nonresectable lung cancer: assessment of local response and therapy-related side effects.

Since 1987, 24 patients with inoperable non-small-cell lung cancer (NSCLC), stage T1-3 N0-2 M0, have undergone lymph node dissection and intraoperative radiation therapy (IORT) to the primary with 10-20 Gy. Patient selection criteria were nonresectability based on severe cardiorespiratory impairment, no radiological evidence of distant metastases and a Karnofsky performance status of greater than 80. In 18 patients the IORT procedure was followed by an external beam radiation series (EBR) including the tumor with 46 Gy and the regional lymph nodes with 46/56 Gy. The tumor response was assessed by CAT-scan volumetry before the institution of IORT, 4 weeks later, before the onset of EBR, 8 weeks after the combined treatment course and on a 3 months basis thereafter. Prospectively, MRI of the thorax with/without Gadolinium-DTPA was performed to examine contrast enhancement and signal behavior of the tumor, in an attempt to differentiate residual disease compared to therapy-related collateral damage. So far, 18 patients have completed the combined treatment course with a median follow-up of 11 months (range 4.5 to 25 months). The overall local response rate (CR and PR) was 88.2%. In detail, 11 complete responses, 6 partial responses and one minimal response were observed. The overall and recurrence-free survival at 25 months was 49.6% and 83.3%, respectively.

Aged↗
PubMed1990

Intraoperative radiation therapy combined with external irradiation in nonresectable non-small-cell lung cancer: preliminary report.

Twenty-one patients with nonresectable non-small-cell lung cancer (15 squamous-cell, 4 adeno, 2 large-cell; T1-T3, N0-N2, all M0) underwent lymph node dissection and intraoperative irradiation of the tumor (IORT) with doses between 10 and 20 Gy (energies: 7 to 20 MeV electron beam). Postoperatively, 46-56 Gy external beam irradiation (8 or 23 MeV photon beam) were delivered to the mediastinum and 46 Gy to the tumor bearing area. Fifteen patients were available for follow-up investigations. The CT-scan tumor volumetry 4 weeks postoperatively showed a significant overall decrease (Wilcoxon test: p less than 0.05) with eight minor responses (MR) (tumor regressions between 4 and 45%) and six partial responses (PR) (between 50 and 84%). One case was not evaluable. A second volumetry after external irradiation was done in 14 patients, 18 weeks after IORT, showing 3 complete responses, 10 partial responses (62 to 84%), and 1 minor response (28%). The recent volumetries (10 patients) between 4.5 and 16.5 months after IORT showed 7 complete responses and 3 partial responses (63 to 94%). One patient died from intrabronchial hemorrhage at 7 weeks. Three others died from unrelated causes, 6, 12 and 14 months, respectively, after IORT and in one further case the cause of death at 15 months was local tumor regrowth. Within the median time elapsed since IORT (12 months) only this one case of local regrowth and one further case of distant spread were observed.

Aged↗
PubMed1990

[A therapeutic concept for the treatment of inoperable esophageal carcinoma].

From 1/87 to 12/88, 20 patients with anatomically or functionally inoperable carcinomas of the esophagus (cT1-3/N0-2/M0-1) were treated by endoluminal Ir-192 HDR brachytherapy (1-3 sessions, each 5-7 Gy) and percutaneous irradiation (50-70 Gy/2 Gy). In 10 cases a bouginage or combined dilatation and retrograde Nd-Yag-laser debulking was done before irradiation. The response of the treatment was documented by endoscopy (degree of stenoses) and symptoms (dysphagia score according to De Meester). In 95% of all cases the degree of stenoses was diminished and an improvement of dysphagia was found in 100%. The mean duration of oral uptake of properly chewed food could be prolonged to 308 days.

Brachytherapy↗
PubMed1990

[Intraoperative radiotherapy (IORT) at the Graz University Clinics: development and dosimetry of an applicator system].

The use of high energy electron beams for intraoperative radiotherapy necessitates special technical adjustments of the conventional megavolt equipment. At the University Clinic of Radiology, Division of Radiotherapy in Graz, an applicator system for electron energies up to 20 MeV and cone diameters up to 14 cm was developed. A self modified commercial operating table was used instead of the treatment couch to guarantee optimum mobility for the docking maneuver. The technical set-up of this adaptor system as well as the dosimetric considerations and calculations will be presented in detail.

Austria↗
PubMed1990

[Radiation planning for electrons].

With irradiation planning for electrons the calculation of dose distribution is very complicated because of dispersion of electrons especially in inhomogeneous medium. Using more efficient computers it is possible to calculate the electron distribution also for clinical application with complicated dose calculation programmes. An arithmetical logarithm according to principle of elementary pencil of rays is described and the correspondence of calculation with measurings at a plexiglass phantom is shown.

Electrons↗
PubMed1990

[Intraoperative radiotherapy (IORT) at the Graz University Clinics: results of a pilot study on non-small cell lung carcinoma].

A pilot study was undertaken during which 15 patients with non-small cell pulmonary carcinomas were exposed to an intraoperative irradiation; twelve out of them were submitted to an additional percutaneous photon therapy. The criteria used to select these patients were functional inoperability, exclusion of remote metastases, and a Karnofsky index greater than 70. Central and peripheral tumors of the stages T1-3, N0-2 were included into the study after histological confirmation of the diagnosis. The local regression rate of the primary tumor can be assessed quite well despite the short follow-up time of 4.5 to 16 months (10 months on an average) which does not yet allow to make a conclusion as to a prolongation of the disease-free survival time. Already two months after the end of external irradiation, a complete remission (CR) was seen in three patients (25%), a partial remission (PR) in seven patients (67%), and a minor remission (MR) in one patient. In the course of further follow-up, the number of complete remissions increased to six (50%). We are encouraged by the small morbidity and a therapeutic response higher than average to continue with this therapy method in patients who, for the time being, are still selected according to strict criteria.

Aged↗
PubMed1990

[3-D reconstruction in radiotherapy].

By means of computed tomography three dimensional compensators can be calculated as dose compensatory bodies for irradiation fields in radiotherapy. This is important especially for shell-type field irradiation and for bilateral total body irradiation. The dose homogeneity, attainable by compensators, is measured at a plexiglas phantom and represented and the use of compensators is described in practice.

Computer Graphics↗
PubMed1989

[Computer-assisted tumor documentation, after-care and medical correspondence in radiotherapy].

Without electronic data processing the recording and statistical evaluation of a great number of tumor patients is only hardly possible. A tumor register and follow-up program is described which has been established for radiotherapy during the development of a national tumor register organized at present. This tumor register also serves as a basis for letter-writing to physicians. The software can easily be adapted to the needs of every hospital because a commercial data bank system has been used. The data input and output is carried out over several terminals. The hardware and software system as well as the incorporation of the data bank into the national tumor register are described.

Aftercare↗