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Biomedical subjects

H Blattmann

Publications and source records attributed to H Blattmann.

At least 55 records · Page 3Linked to original sources
PubMed1988

An intercomparison of two dynamic treatment techniques, ring scan and spot scan, for head and neck tumors with the Piotron.

An evaluation of the ring scan and the spot scan was made for the pion irradiation of head and neck tumors with the Piotron. For the geometry of the Piotron, with its 60 radially converging beams, two scanning techniques have been developed, ring scan and spot scan. They have different characteristics concerning achievable dose distributions and sensitivity to tissue inhomogenities. The optimized 3-dimensional dose distributions for the treatment with ring scan and spot scan techniques were calculated for two examples of the target volume. The comparison of the dose distributions has shown that the ring scan is better in sparing normal tissues than the spot scan for a simple shape target volume but not for an irregular shape target volume with the present status of the technique. The irradiation time needed for the ring scan is longer, for the present examples three times, than for the spot scan. From the practical view point the spot scan is preferable to the ring scan for the treatment of head and neck tumors with the Piotron.

Elementary Particles↗
PubMed1988

[Pion radiotherapy of unresectable soft tissue sarcomas at the Swiss Institute for Nuclear Research].

The Swiss Institute for Nuclear Research SIN at Villigen is one of the three centres in the world (LAMPF, Los Alamos; TRIUMF, Vancouver) where pion therapy is possible. A dynamic, tumour conforming spot scan technique for the treatment of deep-seated tumours has been in use since November 1981. With this technique with a favorable integral dose distribution, curative irradiation also of advanced tumours in the retroperitoneum and pelvis is possible. Only at SIN, the treatment of non-resectable soft tissue sarcomas with pions is part of the clinical program. Between 1983 and 1985 totally nine patients were treated, 1/9 with three manifestations, 1/9 with palliative intent. In 20 fractions over five weeks (four fractions a week) total doses of 30 to 36 Gy (90% isodose) were applied. In a follow-up period of eleven to 43 months (median 18 months) only 1/10 tumour manifestations treated with greater than or equal to 30 Gy failed locally. The two-year survival rate (Kaplan-Meier) is 56%. Metastases were the cause of death in 3/5 patients, 1/5 heart disease, 1/5 local tumour progression. Even though 9/11 tumours were located in the retroperitoneum or pelvis, no radiogenic morbidity of the bowel was found. These preliminary results stimulate the intensification of this clinical program. 1986 the same number of patients with non-resectable soft tissue sarcomas was treated as in the whole period 1982 to 1985 before.

Adolescent↗
PubMed1987

Pionic carbon/oxygen capture ratios in blood and muscle tissue of pig.

The pionic carbon/oxygen capture ratio for the blood and muscle tissue of a pig was measured using an intrinsic Ge detector in order to investigate possible explanations for an enhanced lesion observed in the autopsy of pion-irradiated patients. Pure iron was also irradiated in order to determine the energies and intensities of pionic x-rays from iron. It was expected that some of them originated from haemoglobin and could be observed in the spectrum for a blood sample. TE plastic (Shonka A-150) and Lucite were also investigated for comparison with other work.

Animals↗
PubMed1987

Variations of pion RBE in a volume with an asymmetric beam configuration.

The relative biological effectiveness for the radiation response of mouse jejunum for pions was determined in a clinically relevant asymmetric treatment geometry. A cylindrical volume of 570 ccm, with mouse holders in proximal and distal positions, was irradiated by spot scan technique with a sector of 31 concentric pion beams. The physical dose distribution within the treatment field was homogeneous and the average dose rate was 8.5 cGy/min. The aim was to determine RBE differences between the proximal and distal edge of the field and to compare it with the predictions. The RBE, relative to 200 kVp X-rays, was 1.3 for proximal position and 1.4 for the distal one. The results are in agreement with the calculations of the therapy planning computer program and with the microdosimetric characteristics at the two positions. The variation of the RBE is smaller than for the same field irradiated by a single pion beam.

Animals↗
PubMed1985

The Piotron: II. Methods and initial results of dynamic pion therapy in phase II studies.

Negative pi-meson (pion) therapy employing dynamic scanning with a focused spot of convergent beams has been in use since 1981 at SIN. Three-dimensional conformation of the treatment volume to the target volume can thus be achieved. Following previously reported Phase I and Ib clinical trials, a Phase II trial was initiated with the goal of treating primary deep-seated tumors in a dose optimization schedule which included stepwise increase of total pion dose and of target volume. Patients with multicentric superficial bladder tumors who were cystectomy candidates were initially selected. Since then, more invasive cases have been treated. A graded scoring of acute tissue reactions was employed. Follow-up periods were from 10 to 20 months. The pion dose escalation ranged from 3000 rad (minimum) to 3600 rad (minimum) in 20 fractions over 5 weeks. The treatment volumes encompassed 190 cc for local to 1,820 cc for extended volume therapy. Treatment reactions ranged from a faint erythema and increase of bladder frequency to dry desquamation, mild nausea, moderate dysuria, and moderate proctitis or diarrhea with mucus. These reactions were closely related to treatment volume and site. One severe late cystitis has occurred in a patient treated with 2 courses of pions (4475 rad). Mild to moderate late proctitis has been seen in 4 patients. Ten of 13 bladder cancer patients had local control of disease while all 3 pancreas or biliary tract cancer patients had microscopic residual disease locally at time of death from metastasis. A total of 11 of 17 patients are thus clinically or pathologically free of local tumor to time of last observation.

Bile Duct Neoplasms↗
PubMed1985

Proportional counter dosimetry and microdosimetry for radiotherapy with multiple pion beams.

At the Swiss Institute for Nuclear Research (SIN) cancer patients are irradiated with negatively charged pi mesons using a 60-beam medical pion generator, the Piotron. A low-pressure tissue-equivalent proportional counter was used to measure absorbed dose and microdosimetric spectra. A method was developed to allow discrimination of events from different beam components, i.e., beam contamination (electrons and muons), pions in flight, and stopping pions. Measurements were performed along the axis and at lateral distances off one of these identical pion beams. The marked changes of total microdosimetric spectra with depth in phantom detected in earlier measurements are mainly due to large variations in the dose contributions of the beam components and much less to changes in the shapes of the individual microdosimetric spectra. The single beam measurements were used to calculate three-dimensional distributions of absorbed dose and of dose mean lineal energy, yD, for dynamic patient irradiations. Within the whole target volume yD remains nearly constant when irradiated with all 60 beams, whereas considerable changes were found for irradiations with 31 beams coming from a semicircle. Both size and shape of target volumes influence yD, the maximum values ranging from 30 to 45 keV/micron.

Elementary Particles↗
PubMed1985

Review of the SIN and Los Alamos Pion Trials.

Negative pi mesons (pions) were used to treat 227 patients at the Los Alamos Meson Production Facility (LAMPF) between 1974 and 1981. Persisting local control values for 129 patients treated with pions alone in the following tumor sites were recorded at a minimum post-treatment observation interval of 2.5 years in the following tumor sites: cerebral gliomas 3/29; head and neck, 8/31; lung, 1/7; pancreas, 0/17; large bowel, 3/13; cervix, 2/45; bladder, 3/4; prostate, 18/20; miscellaneous sites, 0/4. Late severe sequelae ranged from none to 30% for major sites. A dose-response relationship was seen for late severe sequelae with a high probability following dose levels of 4750 cGy (max) in approximately 38 fractions. RBE values for pions appeared to lie in the range of 1.4-1.6 for both acute normal tissue reactions and late sequelae. At the Swiss Institute for Nuclear Research (SIN), 126 patients were treated in Phase I-II protocol studies between 1982 and 1984 with a new technique of scanning with a focused spot of pions. With minimum observation intervals of only 6 months, the local complete response values in 67 evaluable patients treated with pions alone to selected sites are gliomas 1/15 (9 months); pancreas, 3/11; cervix, 4/8; bladder, 18/26 (at 1 year, 9/22); sarcomas, 4/5; biliary tract, 3/4. Late severe sequelae ranged from none to 50% for major sites. A steep dose-response relationship is seen for late severe sequelae with high probability following doses exceeding 3800 cGy (max) in 20 fractions and very low probability with doses below 3500 cGy (max).

Brain Neoplasms↗
PubMed1985

Results of curative pion therapy at SIN.

The experiences of the treatment of bladder carcinoma indicated the direction in which the dose optimization program of intraabdominal tumours can be carried out. Small intraabdominal target volumes seem to tolerate doses from 31 to 33 Gy applied in 20 fractions. The best results with local tumour control and low complication rates have so far been reached in carcinoma of the cervix. It has not so far been organizationally possible at SIN to treat with pions on more than four days per week. This restricts changes to the fractionation scheme in the treatment of highly malignant gliomas. An improvement of results could be possible on the basis of experience to date. The significance of a postbiopsy preoperative radiotherapy, of the increase of target volume and the increase of the total dose will be tested in a study by the SAKK (Swiss Group for Clinical Cancer Research).

Elementary Particles↗
PubMed1984

[Effectiveness of high-dosage radioiodine therapy in the elimination of remnant tissue following total thyroidectomy].

The efficacy of high doses of radioiodine for total ablation of functional remnants left behind after total surgical thyroidectomy for thyroid cancer decreases with the number of treatments as well with the course of therapy. Most effective are 500 mCi of 131I administered in 5 fractions within 3 years. Up to 1000 mCi of 131I delivered within 5 years are still powerful but much less so. All further treatments with high doses of radioiodine are only of diagnostic value for detection of functional metastases with low radioiodine uptake. In about 45% of all patients even excessively high doses of radioiodine failed to ablate all functional residual thyroid tissue.

Adenocarcinoma↗
PubMed1983

[Effect of the plan of therapy on prognosis in thyroid cancer].

The therapeutic concept used in our Department for the treatment of thyroid cancer is characterized by a facultative external irradiation of the neck region and by a mandatory and intense treatment with radioiodine. The latter includes a complete elimination of remaining normal thyroid tissue and a combined diagnostic add therapeutic radioiodine application in the follow-up of the disease. The therapeutic effect of surgery, hormone substitution, radioiodine treatment and external irradiation combined with the prognosis of thyroid cancer was obvious, but that of individual steps was difficult to separate and quantitate. External irradiation of the neck improved the prognosis of patients with anaplastic carcinoma but no significant effect was observed in patients with follicular carcinoma. Even after prophylactic treatment with high doses of radioiodine the prognosis of differentiated thyroid cancer remained to be highly dependent on biological factors. Radioiodine treatment is recommended in all patients with follicular carcinoma and in patients older than 30 years with papillary carcinoma, but prophylactic treatment should only be performed for a period of 5 years.

Adenocarcinoma↗
PubMed1982

The PIOTRON: initial performance, preparation and experience with pion therapy.

The PIOTRON is a large solid angle superconducting channel built for the use of negative pi-mesons in radiotherapy. The pions are produced by protons of 590 MeV striking a target of molybdenum or beryllium. The pions are divided into 60 channels and deflected twice to enter the treatment volume radially. The momentum and the momentum band for all 60 channels can be chosen and the beam spot of Bragg peak pions at the isocenter of the applicator is a few centimeters in each direction. Dynamic scanning can thus achieve 3-dimensionally shaped treatment volumes. Two different methods are available: the ring scan, using changes of pion range; and the spot scan, involving translation of the patient through the fixed beam spot. Dose distributions of individual and multiple beams were plotted in a cylindrical water phantom. Radiobiological experiments with mammalian cells in gel and with mouse feet were performed. A special beam geometry using a sector of 15 beams was selected for the first treatments of patients with metastatic skin nodules. Six patients were treated. Acute skin reactions were scored and compared with those from orthovoltage therapy with comparable beam geometry. The RBE for 10 fractions is between 1.4 and 1.5. The next step involved treatment of patients inside water-bolus rings in preparation for dynamic therapy. Patients were then treated with the spot scan dynamic mode in the water bolus. The initial responses and reactions are favorable and confirm the feasibility and accuracy of dynamic pion therapy.

Elementary Particles↗
PubMed1980

Pion dosimetry with thermoluminescent materials.

Various thermoluminescent materials (6LiF, 7LiF, Li2B4O7:Mn, CaSO4:Dy, CaF2:Mn, CaF2-Dy, CaF2:Tm) were irradiated with pi- mesons throughout the depth dose distribution of a beam with central momentum of 176 MeV/c. Doses from 0.05 to 2 Gy were used and linearity and reproducibility were investigated. For LiF, CaF2:Dy and CaF2:Tm, low- and high-temperature peaks were analysed separately. CaF2:Tm was found to be the most suitable for pi- dosimetry since the total dose and the high LET component could be determined using the integral TL signal and the peak height ratio of the 150 degrees C and 240 degrees C peaks. In the dose range used, both peak responses are linear with dose and the sensitivity of the materials is 10 times that of LiF. The reproducibility was +/- 3%. The high temperature peak of 7LiF is too small to be determined accurately and the high temperature peak of CaF2:Dy decreases with increasing LET in the same way was the low temperature peak does, so that no LET information can be extracted.

Calcium Fluoride↗
PubMed1979

Energy deposition spectra of negative pions and their application to radiation therapy.

Treatment planning for pion radiation therapy must take into account changes in radiation quality within the patient. At the biomedical channel piE3 of SIN (Swiss Institute for Nuclear Research) microdosimetric measurements have been performed to investigate radiation quality within pion irradiated phantoms. Results are presented in terms of microdosimetric spectra and derived quantities. As expected marked differences are observed between dose peak and plateau for "narrow" pion beams. The influence of simulated site diameter on measured spectra has been found to be more pronounced in the plateau region than in the peak. Investigation of the influence of peak width on radiation quality revealed a dilution of the high-LET dose fraction for broader peaks.

Elementary Particles↗
PubMed1979

Effect of negative pions, relative to 140 kV -- 29 MeV photons and 20 MeV electrons, on proliferation of Ehrlich ascites carcinoma cells.

The effect of negative pions (peak and plateau), photons (140 kV and 29 MeV), and 20 MeV electrons on the proliferative capacity of Ehrlich ascites carcinoma cells was investigated. Proliferative survival curves plotted for the modalities employed are presented. Under the experimental conditions used, the peak pions were more effective than plateau pions by a factor of about 1.4. For 50% survival, 140 kV X-rays had the same effect as peak pions but the latter was more effective (factor 1.2) at 10% survival level. When 140 kV X-rays were taken as the standard, following are the RBE values calculated as 50% survival level: plateau pions --0.73; peak pions --about 1.0; 29 MeV photons --0.73 and 20 MeV electrons --0.6. The results obtained are compared with those reported on other tumor systems and biological test objects.

Animals↗
PubMed1979

Cell survival over the depth profile after irradiation with a negative pion beam.

The colony-forming ability of Chinese hamster fibroblast cells in vitro has been investigated throughout the depth dose profile of a negative pion beam. In the peak and 2 cm beyond, the RBE for macroclones (more than 50 cells per clone) was 1.3 and in the plateau region 0.8--1.0. All of the microclones (2-49 cells per clone) were observed as well. The RBE values are the same for peak and somewhat higher for plateau and post peak than found in cell survival studies referring to macroclones.

Animals↗
PubMed1979

Chromatid breaks induced in Chinese hamster cells by low doses (12--100 rad) of pi--mesons.

Monolayer cultures of the fibroblast-like Chinese hamster cell-line 19/1 were irradiated in the G2-phase of the cell cycle by pi--mesons (6 rad/min peak-pion dose rate). Frequencies of induced single- and isochromatid breaks, acentric fragments and interchanges were compared with data obtained from 140 kV X-rays. The RBE-values were for the pion dose peak between 0.8--1.2 and for the pion dose plateau 0.5--0.9. Whereas for single chromatid breaks there was no significant difference between X-rays and peak pions for identical physical doses, the isochromatid breaks alone showed a significantly higher frequency for 100 rad peak pions.

Animals↗
PubMed1979

Preclinical radiobiology with pions: RBE--values for mouse skin damage as a function of single doses of pions.

The macroscopic reaction of the mouse skin was used to derive RBE values for negative pi-Mesons. Hind limbs of mice were irradiated with pions or X-rays. The pions were produced by the 590 MeV accelerator of the Schweizerisches Institut für Nuklearforschung (SIN). Early reaction was assessed over a period of 6--30 days after irradiation with single doses (20--45 Gy). The radiation damage was scored using an arbitrary scale of effect. The time pattern of development of the skin reaction and the subsequent healing after exposure both to pions and X-rays were similar, indicating that depletion and repopulation of the basal cells of the skin were comparable, both after pions and X-rays. RBE values as a function of pion doses at the peak (dose maximum), plateau and at the postpeak (12 mm downstream of the dose maximum) were computed with nonparametric statistical methods. The RBE at the peak and at the plateau relative to X-rays of the same dose rate was 1.15--1.25 and 0.85, respectively. The RBE of peak pions manifested a marked dependence on dose, when plateau pions were chosen as reference radiation. In this experiment there was no significant difference in RBE between peak and postpeak. The importance of some experimental condition (dose rate, irradiation volume) is discussed.

Animals↗