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D Fehrentz

Publications and source records attributed to D Fehrentz.

At least 19 recordsLinked to original sources
PubMed2000

Cataract incidence after total-body irradiation.

PURPOSE: The aim of this retrospective study was to evaluate cataract incidence in a homogeneously-treated group of patients after total-body irradiation (TBI) followed by autologous bone marrow transplantation or peripheral blood stem cell transplantation. METHODS AND MATERIALS: Between 1982 and 1994, a total of 260 patients received either autologous bone marrow or blood stem cell transplantation for hematological malignancy at the University of Heidelberg. Two hundred nine of these patients received TBI in our hospital. Radiotherapy was applied as hyperfractionated TBI, with a median dose of 14.4 Gy in 12 fractions over 4 days. Minimum time between fractions was 4 h. Photons with an energy of 23 MeV were used with a dose rate of 7-18 cGy/min. Ninety-six of the 209 irradiated patients were still alive in 1996; 86 of these patients (52 men, 33 women) answered a questionnaire and could be examined ophthalmologically. The median age at time of TBI was 38.5 years, with a range of 15-59 years. RESULTS: The median follow-up is now 5.8 years, with a range of 1.7-13 years. Cataract occurred in 28/85 patients (32.9%) after a median of 47 months (1-104 months). In 6 of 28 patients who developed a cataract, surgery of the cataract was performed. Whole-brain irradiation prior to TBI had been performed more often in the group of patients developing cataract (14.3%) versus 10.7% in the group of patients without cataract. However, there was no statistical difference (Chi-square, p>0.05). CONCLUSION: Cataract is a common side effect of TBI. Cataract incidence found in our patients is comparable to results of other centers using a fractionated regimen for TBI. To assess the incidence of cataract after TBI, a long-term follow-up is required.

Adult↗
PubMed1998

[Performance of electron-beam CT: continuous-volume-scan compared to spiral CT].

To compare patient dose and image quality of electron-beam-CT vs. spiral-CT by means of phantom measurements. An EBCT scanner (C-150 XP) and a spiral-CT scanner (GE HiSpeed Advantage) were used to scan three different phantoms. Administered dose, high contrast (HC) resolution, low contrast (LC) lesion detectability and the width of the radiation beams were measured. EBCT showed 25-35% lower HC resolution in comparison to spiral-CT. LC lesion detectability showed equivalent results for S/N vs. patient dose using 3 mm collimation with EBCT and spiral-CT, whereas spiral-CT was superior for 1.5 and 6 mm collimation. Dose measurements revealed a 2 fold higher patient dose using EBCT with 1.5 mm or 6 mm collimation compared to spiral-CT using equivalent scan parameters. No differences were seen using 3 mm collimation. Differences were due to insufficient beamside collimation of the EBCT. The use of EBCT with 6 mm collimation should be avoided, because of impaired performance. Using 3 mm collimation, EBCT showed comparable performance like state of the art spiral-CT despite lower HC resolution.

Algorithms↗
PubMed1998

[Low-dose computerized tomography of the jaw bone in pre-implantation diagnosis. Limits of dose reduction and accuracy of distance measurements].

Absorbed radiation doses delivered by computed tomography and panoramic radiography were measured in 16 anatomic sites using a head and neck phantom and thermoluminescent dosimetry. The recommended kilovoltage and scan time for dental scanning was reduced step by step, rating the quality of the low-dose scans. A reduction of up to 76% could be achieved without loss of diagnostic accuracy. Measured absorbed radiation dose ranges from 0.30 mGy (thyroid) to 29 mGy (skin) at 187.5 mAs and 1.0 mm-slices (25 mm scanning distance for maxilla, 30 mm for mandible). After reduction to 45 mAs, 0.07 mGy (thyroid) to 6.9 mGy (skin) was measured. Distance measurements on human jaw specimens were compared with corresponding CT image measurements. Average deviation was 0.1-0.3 mm. A dose reduction of 75% had no effect on the results. However, the doses of CT-scans reduced by 76% exceed by an average factor of 10 the doses of conventional panoramic radiography. Therefore, CT should be reserved for the planning of complex implant treatment in the direct vicinity of the maxillar sinus and nerves and for multiple implant insertion.

Body Burden↗
PubMed1998

Lethal pulmonary toxicity after autologous bone marrow transplantation/peripheral blood stem cell transplantation for hematological malignancies.

BACKGROUND AND PURPOSE: Retrospective evaluation of the incidence of lethal pulmonary complications (LPC) with special emphasis on interstitial pneumonia (IP) in a large group of patients homogeneously treated with hyperfractionated total body irradiation (HTBI) before autologous bone marrow transplantation (ABMT) or peripheral blood stem cell transplantation (PBSCT) for hematological malignancy. The factors influencing IP are discussed. MATERIALS AND METHODS: Of 260 patients (maximum follow-up 137 months) that were treated with ABMT or PBSCT for hematological neoplasms between 1982 and 1994, 209 patients received HTBI and could be evaluated with respect to lethal pulmonary complications and especially lethal interstitial pneumonia. For most patients (n = 155), the HTBI dose was 14.4 Gy (lung dose 9-9.5 Gy) given in 12 fractions over 4 days. Twenty-one patients received a total dose of > or =15 Gy with pulmonary doses of 9-10.5 Gy. RESULTS: The actuarial overall 5-year survival for all 209 patients evaluated was 44 +/- 4%, enabling valid evaluation with respect to lethal pulmonary toxicity. The actuarial incidence of all LPC during the first year was calculated as being 8 +/- 2%. The actuarial incidence of lethal IP is certainly lower and was estimated to be between 3 and 5% for all patients. The overall treatment-related mortality was 12% in 188 patients that received a total dose of <15 Gy and 24% among the patients treated with a total dose of > or =15 Gy. CONCLUSION: ABMT/PBSCT, like other transplant modalities without significant graft versus host disease (GvHD), has a low transplant-related mortality, a very small rate of overall LPC and a low incidence of lethal IP after HTBI. Doses up to 14.4 Gy with lung doses of 9-9.5 Gy can be administered safely. For total doses of > or =15 Gy with lung doses of 9-10.5 Gy, the risk of serious transplant-related complications cannot yet be finally assessed but such higher doses should be considered with caution because of the possibility of increasing toxicity in organs other than the lung.

Adolescent↗
PubMed1992

[The improved determination of the dose rate in irregular photon fields].

A revised formula for calculation of dose per time or monitor unit ("dose rate") of irregular megavoltage photon beams is proposed. The formula considers additionally the shading by secondary shieldings of the plane source describing the scattered radiation in the head. Therefore, in addition to the primary output factor C(ac) as function of the equivalent square ac x ac of the collimator field size a secondary output factor S(as) is introduced denoted as function of the equivalent square as x as of the irregular field. S is determined using a satellite diaphragm formed of shielding blocks in combination with a totally opened collimator. In this definition, S includes both the effects of radiation scattered in tissue (phantom scatter factor PSF) and of missing photons from the plane source by the blocks (satellite diaphragm factor SAT). In the usual formula to calculate the "dose rate" (output) at reference point in depth t, PSF is replaced by S: D = D0 x C(ac) x [PSF(as)/PSF(ac)] x T x R(as,t). There T is representing the block tray factor and R(as,t) the tissue phantom ratio or relative depth dose, depending on the irradiation technique used. Thus the modified formula is given by D = D0 x C(ac) x [S(as)/S(ac)] x T x R(as,t). Measurements show that the revised formula provides an additional precision of up to 2% in the calculation of dose, depending on the type of accelerator respectively on the size of the plane source of scattered radiation.

Humans↗
PubMed1989

Disease-free survival after autologous bone marrow transplantation in patients with acute myelogenous leukemia.

Autologous bone marrow transplantation (ABMT) makes it possible to escalate the dose of cytotoxic treatment to a lethal range. Disease-free survival (DFS) following myeloablative therapy and ABMT has been shown to be superior to conventional treatment in high risk patients with acute myelogenous leukemia (AML). It was the purpose of the present study to compare hematopoietic reconstitution, actuarial DFS, and relapse rate of patients transplanted in first complete remission (CR) of AML with those in second or subsequent CR, and to evaluate transplant related mortality. Fifty-two patients with AML, 22 in first CR (low risk) and 30 in second or subsequent CR (high risk), underwent total body irradiation (12.1 to 16.7 Gy) and cyclophosphamide (CY) treatment (200 mg/kg) followed by ABMT. The autograft was incubated with the active CY derivative Mafosfamide (ASTA Werke, Bielefeld, Federal Republic of Germany) to reduce the number of possibly contaminating clonogenic tumor cells. All patients showed three lineage engraftments with platelet recovery observed as being the slowest. The transplant related death rate was low at 5.8%. There was no significant difference in the kinetics of polymorphonuclear (PMN) cell or platelet reconstitution between the low and high risk patient subgroups. The estimated probability of DFS (relapse) after ABMT in first CR was 61% (36%) compared with 34% (65%) in second or subsequent CR, the longest follow-up being 55 months and 57 months, respectively (median follow-up 31 months and 19 months, respectively). ABMT offers a stable long-term DFS when performed in first CR with no relapses occurring in over a year after transplantation. Six later relapses, however, were seen after ABMT in second or subsequent CR, although DFS was not statistically different from that of first remission patients (P = .72).

Adult↗
PubMed1989

Long-term endocrine toxicity of myeloablative treatment followed by autologous bone marrow/blood derived stem cell transplantation in patients with malignant lymphohematopoietic disorders.

The effect of myeloablative treatment with autologous bone marrow transplantation (ABMT)/autologous blood derived stem cell transplantation (ABSCT) in patients with acute leukemias or lymphomas was studied in 32 adult patients with a mean observation time of 15.8 months after transplantation. The conditioning regimen consisted of hyperfractionated total-body irradiation (TBI) and high-dose cyclophosphamide or the cyclophosphamide, carmustine, and etoposid (CBV) regimen. In all of the female patients, we observed primary ovarian failure requiring estradiol replacement therapy. In all of the male patients, testosterone levels were normal but follicle stimulating hormone (FSH) levels were increased, suggestive of germinal aplasia which was proved by semen analysis in several patients. In contrast to the reports of other groups, we did not find any abnormalities in thyroid function, most likely because TBI was hyperfractionated. Moderate toxicity to the adrenal cortex was noticed and was more pronounced in women than in men. Our results are similar to findings reported after allogeneic bone marrow transplantation, with the exception of normal thyroid function in our patients. These results should be taken into consideration when counseling patients about the long-term consequences of myeloablative treatment. Cryopreservation of semen should be offered to men before myeloablative treatment. Estrogen replacement should be initiated after transplantation in women to prevent adverse effects of long-term ovarian failure.

Adult↗
PubMed1989

Analysis of late effects data using dose-response models: application to human skin telangiectasia data.

The clinical data for skin telangiectasia from previous prospective studies at the Radiotherapy Department in Gothenborg are reanalyzed using two dose-response models - the general formulations of the well known linear-quadratic (LQ) and NSD isoeffect models. Assuming that essentially no repopulation appears in the vessel endothelium for overall treatment times up to 68 days, the alpha/beta-value of 2.75 Gy is obtained for the LQ-model. The time factor is found not to be significant by the NSD-model for the treatment times used (less than or equal to 68 days) at the 95% level of confidence. The estimated value of the exponent of the number of fractions, A, is 0.321. The obtained values of the alpha/beta-ratio and of A show high sensitivity of the vessel endothelium to changes in the dose per fraction. Our results show that within the interval of the number of fractions used, 10-35 fractions, the NSD-model gives predictions comparable to those of the LQ-model. For number of fractions smaller than 5, a high discrepancy occurs between the two models, the NSD-model predicting higher values of the isoeffective total dose. The maximal deviation between the models appears for N = 1; 25% and 27% at the 5 and 50% level of effect, respectively. For large N and especially at low effect probabilities the NSD-model again predicts higher isoeffective doses: the dose predicted by the NSD-model for a regimen with 40 fractions and for 5% probability of telangiectasia is 7.5%, higher than that predicted by the LQ-model. Based on the estimated dose-response curves, considering the telangiectasia as the decisive late tissue effect, the requirement for the combined uncertainty in the dose delivery is estimated between 3 and 4.5%.

Dose-Response Relationship, Radiation↗
PubMed1987

[Detailed structural analysis of the petrous bone using high-resolution thin-layer computerized tomography. 1. Sensitivity of substructural demonstration using a standardized study technic].

High-resolution CT, using fine sections, is a valuable method for radiological examination of the petrous bone. A standardized method of examination using the orbitomeatal and coronary plane is adequate for detailed screening of the petrous bone and shows almost all structures with high accuracy. The sensitivity of the method for showing 35 sub-structures of the inner and middle ear was investigated by examining 40 petrous bones which were normal clinically and radiologically, using the orbito-meatal and coronary planes. The radiation dose to the lens is less than from pluri-directional tomography. For special problems and for demonstrating very small structures, cuts may have to be performed in other planes, suitable for the required topography.

Ear, Middle↗
PubMed1986

Hyperfractionated total body irradiation as part of autologous bone marrow transplantation.

On 14 patients with acute leukemia and non-Hodgkin lymphoma autologous bone marrow transplantation (ABMT) was performed together with high dose cyclophosphamide and hyperfractionated total body irradiation. The radiotherapy was given at a total dose of 13.2 Gy distributed over eleven fractions of 1.2 Gy and four days. All eleven patients transplanted in complete remission are alive, among them ten in unmaintained complete remission at a longest observation time of two years.

Bone Marrow Transplantation↗
PubMed1985

[Contact therapy in the pharynx and oral cavity areas: after-loading technic, irradiation planning and results].

The contact irradiation in the region of pharynx and mouth with an afterloading unit is presented. Twelve patients with recurrent carcinomas of the squamous cell epithelium have been treated. A stable and reproducible positioning of the source probes in the tumor region is made possible by special applicator prostheses which are adapted to the post-operative situation. The irradiation scheme is based on the transformation of the source co-ordinates from the stereoradiographic localization system into the co-ordinate system of the computed tomogram. At least three fixed metal points which are inserted in the applicator prostheses and visualized by stereoradiography as well as by computed tomography serve as mutual reference points for both co-ordinate systems. The source positioning in the tumor region is optimized by CT irradiation planning. Three cases are presented in order to describe the principles of the method. Preliminary results are discussed.

Brachytherapy↗
PubMed1985

[Use of electrons above 20 MeV for reduction of radiation exposure].

After many years of clinical application of a 42 MeV betatron, the following indications were found for deep therapy with electrons above 20 MeV: tumors situated in the brain, mediastinum, kidney, liver, bladder, rectum, as well as peripheral tumors situated in different body regions. For eight different cases, the total body exposure and the radiation exposure of some risk organs was calculated for an irradiation with electrons alone, a combination of electrons and photons, an irradiation with 42 MeV X-rays and with Co-60 gamma rays alone. All these calculations were based on a most favorable irradiation technique. The results showed that electrons up to 40 MeV can spare more than 30% of the total body dose; a combination of electrons and photons allows a reduction of the total dose of about 15% as against that of photons alone, which makes possible a better conservation of skin. This total dose reduction corresponds to that achieved by the substitution of ultrahard X-radiation for Co-60 gamma radiation in deep therapy. The radiation exposure of risk organs can often be reduced by the use of electrons, too. Thus electron deep therapy shows to be justified for the mentioned tumor cases. This is also confirmed by clinical experience.

Beta Particles↗
PubMed1983

[Neutron pollution in roentgen beams from electron accelerators].

The neutron dose was measured in X-ray beams with a limiting energy of 8 to 45 MeV and in 42 MeV electrons (10 X 10 cm2) from several electron accelerators (betatrons, linear accelerators, microtron). The measurements were taken with activation probes and nuclear films of polycarbonate coated with 0,5 mm Cd. On a 42 MeV betatron, the neutron spectrum, the density of neutron flow and the neutron dose of the central ray were evaluated in a paraffin phantom by means of seven threshold value reactions. The neutron spectrum showed only a small dependence on depth. The neutron equivalent dose (with Q approximately equal to 10) was 13 mSv at the surface per Gy of the absorbed dose of 42 MeV X-rays in the dose maximum. The neutron dose contribution to the dose maximum was only a little higher and showed a curve resembling to the depth dose curve of X-radiation. In case of 42 MeV electrons, the neutron equivalent dose was 0,8 mSv per Gy of the electron dose at the surface of the phantom. The measurements taken by means of nuclear films showed a monotonous increase of the equivalent dose contribution of fast neutrons from 0,8 mSv in case of 8 MeV to 15 mSv in case of 45 MeV X-rays per Gy of the primary radiation dose in the dose maximum. The increase became lower above 25 MeV and was not dependent on the field size or on measurements with or without phantom.

Electrons↗
PubMed1979

[The diagnostic significance of microcalcifications in testicular tumors (author's transl)].

The evaluation of total orchiectomy tissue specimens with malignant testicular tumors shows that microcalcifications can be found in a surprisingly high percentage by radiological and histological examinations. Small, often in several groups located calcifications in the parenchyma neighbouring the tumor are typical for seminoma, whereas in teratoma solitary microcalcifications and polymorphic types can also be seen. Microcalcifications are also present in not neoplastic testicular diseases but in a much smaller percentage and with a different type of calcification. The preoperative radiographic examination of testicular tumors of unknown origin seems to be indicated as a non-invasive method able to provide further information about the presence of a malignant germ cell tumor. Regarding the genetic risks of the method, there is hope to avoid other more invasive examinations with their danger of tumor spreading and to enable a radical resection of the primary tumor before its metastic formation by the mean of preoperative orchioradiography.

Calcinosis↗