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At least 127 records · Page 7Linked to original sources
PubMed1994

The relative cellular radiosensitivity of 30 human in vitro cell lines of different histological type to high LET 62.5 MeV (p-->Be+) fast neutrons and 4 MeV photons.

It has been suggested that fast neutron therapy may have a role in the treatment of those tumours which lie within the most photon-resistant histological categories. A clinical radiobiological study by Battermann et al., however, did not support this hypothesis (Battermann, J.J. et al., Eur. J. Cancer 17: 539-548, 1981). Similarly, in a comparison of the intrinsic cellular radiosensitivity of 20 human in vitro cell lines with 4 MeV photons and 62.5 MeV (p-->Be+) neutrons, there was no correlation between RBE and photon sensitivity. However, because the range of histological cell types in this in vitro study did not include sufficient representatives of the most sensitive and resistant histological categories, it was not possible to examine the relationship between histology and the relative efficacy of fast neutrons compared with photons. The intrinsic radiosensitivity of a further 10 human in vitro cell lines has thus been measured and the results of all 30 cell lines used in a comparison of the relationship between relative neutron sensitivity and histology. These results together with those obtained by reanalysis of published data from a clinical study of the RBE of pulmonary metastases by Battermann et al. suggest that in the clinical situation, photon-resistant histology per se may not be a sufficient criterion for the choice of high LET irradiation and emphasize the need for predictive assays for individual tumours.

Energy Transfer↗
PubMedDate not supplied

Fast neutron irradiation in advanced pre-irradiated head and neck tumors.

AIMS AND BACKGROUND: Radiotherapy with fast neutrons offers radiobiological advantages in the treatment of hypoxic and slowly proliferating tumors. Tumors recurring in pre-irradiated areas of the head and neck usually exhibit a low radiation sensitivity that seems to promise little success for a repeated irradiation with photons. In such a situation, radiotherapy with fast neutrons may offer an alternative treatment option. To evaluate the question, the Muenster patients were retrospectively analyzed. METHODS: During the period July 1986 to January 1994, 26 patients with local-regional recurrences of pre-irradiated head and neck tumors were treated with fast neutrons at our department. RESULTS: Median survival calculated by the Kaplan-Meier method was 7.4 months. The 1-year survival probability was 29.3% and the 2-year survival probability 5.9%. The objective tumor remission (complete + partial) was 50%. A subjective improvement of symptoms was reported by 42.3% of all patients. CONCLUSIONS: Despite relatively unfavorable survival rates produced by the therapy, good remission rates and thereby a good palliative effect can be attained with a short treatment time and tolerable side effects.

Adult↗
PubMed1984

The response of mouse skin to hyperthermia combined with fast neutrons or X-rays.

The effects of hyperthermia combined with fast neutrons (mean energy approximately 7.5 MeV) or X-rays (250 kVp) were studied in the skin of the mouse ear and foot. Hyperthermia was achieved by immersion in water at temperatures of 41.5-43.0 degrees C for 1 hour. The heat treatments used caused no observable tissue injury other than transient erythema but they enhanced the response to both neutrons and X-rays. The enhancement of neutron damage increased as the heating temperature was increased, as is well known for X-rays. When heat was given after irradiation the thermal enhancement ratio (t.e.r.) for neutrons was similar to that for X-rays. When heat was given before irradiation the neutron t.e.r. was less than that for X-rays. Consequently, the relative biological effectiveness of fast neutrons compared with X-rays was not altered by giving heat after irradiation but it was reduced by giving heat before irradiation.

Animals↗
PubMed2003

Monte Carlo evaluation of a photon pencil kernel algorithm applied to fast neutron therapy treatment planning.

When dedicated software is lacking, treatment planning for fast neutron therapy is sometimes performed using dose calculation algorithms designed for photon beam therapy. In this work Monte Carlo derived neutron pencil kernels in water were parametrized using the photon dose algorithm implemented in the Nucletron TMS (treatment management system) treatment planning system. A rectangular fast-neutron fluence spectrum with energies 0-40 MeV (resembling a polyethylene filtered p(41)+Be spectrum) was used. Central axis depth doses and lateral dose distributions were calculated and compared with the corresponding dose distributions from Monte Carlo calculations for homogeneous water and heterogeneous slab phantoms. All absorbed doses were normalized to the reference dose at 10 cm depth for a field of radius 5.6 cm in a 30 x 40 x 20 cm3 water test phantom. Agreement to within 7% was found in both the lateral and the depth dose distributions. The deviations could be explained as due to differences in size between the test phantom and that used in deriving the pencil kernel (radius 200 cm, thickness 50 cm). In the heterogeneous phantom, the TMS, with a directly applied neutron pencil kernel, and Monte Carlo calculated absorbed doses agree approximately for muscle but show large deviations for media such as adipose or bone. For the latter media, agreement was substantially improved by correcting the absorbed doses calculated in TMS with the neutron kerma factor ratio and the stopping power ratio between tissue and water. The multipurpose Monte Carlo code FLUKA was used both in calculating the pencil kernel and in direct calculations of absorbed dose in the phantom.

Adipose Tissue↗
PubMed1979

Preliminary report of the M. D. Anderson Hospital/Texas A & M variable energy cyclotron fast-neutron therapy pilot study.

The records of 248 patients treated with fast neutrons and of 102 comparable but nonrandomized control patients treated conventionally with photons, surgery, or combined surgery and photon irradiation were reviewed. Fast neutron therapy included treatment with neutrons alone, a neutron boost after photon therapy, or a schedule of alternating neutron and photon treatments (mixed beam). The results with mixed beam irradiation were superior to those obtained with the other neutron therapy techniques, and compared favorably with the results of standard treatment methods. However, the lack of a conclusive advantage for neutron therapy in this pilot study illustrates the need for on-going randomized clinical trials.

Adenocarcinoma↗
PubMed2001

Monte Carlo simulation of fast neutron spectra: mean lineal energy estimation with an effectiveness function and correlation to RBE.

PURPOSE: Intercomparisons of radiotherapy trials conducted at different fast neutron facilities are complicated by the dependence of the relative biologic effectiveness (RBE) of the different beams on the fast neutrons spectra. To obtain a better understanding of the influence of neutron energy on radiation quality, Monte Carlo simulations were performed to calculate fast neutron (FN) spectra at different irradiation positions. To allow for comparisons with experimental data, the positions were chosen to be the same as that used by other investigators to obtain microdosimetry readings and radiobiological data. METHODS AND MATERIALS: The primary neutron yield for beryllium targets bombarded with protons at the National Accelerator Center, Louvain, Nice, and Orleans facilities were calculated using the FLUKA code. Neutron transport simulations were performed with MCNP-4A, giving FN spectra for various phantom depths, hardening filter thickness, and field sizes. Using an effectiveness function, FN energy groups were correlated with mean lineal energies (y*-values) obtained experimentally by other workers. RESULTS: Calculations confirm earlier measurements that a decrease in beam quality by a hardening filter is the result of a reduction in the low-energy neutron component, i.e., neutrons below 3 MeV. Variations in RBE due to changes in field size and different phantom depths could also be explained by variations of neutrons with energies between 3-15 MeV. The effectiveness function allows one to calculate changes in y* observed for the NAC beam with great accuracy (R(2) = 0.99, p < 0.0001). Also, when this function is applied to beams with different neutron energies, y* calculated values show a very significant correlation with measured RBE values (R(2) = 0.98, p < 0.0001). CONCLUSION: The effectiveness function appears to be suitable to predict changes in y*-values and variations in RBE, using FN spectra simulated for various neutron therapy facilities.

Beryllium↗
PubMed1989

[Fast neutron radiotherapy of prostate cancer].

Between 1976 and 1987, sixty eight patients suffering from prostate cancer were treated with fast neutron radiotherapy at the NIRS hospital in Chiba, Japan. Tumor doses of TDF 100 were administered to the prostate gland, the regional lymphnodes, and the true pelvis, using the two opposing fields by fast neutron alone or with a boost. The overall local or regional tumor recurrence rate was found to be 10% and local control seemed to correlate with the histological differentiation of the cancer tissue, though there was no definite correlation with hormone treatment. A relatively high incidence of grade 3 and 4 radiation complications were observed, 21% for grade 3 and 7% for grade 4, due to subcutaneous fat necrosis caused by an inferior dose distribution of the fast neutron machine. The 5-year survival rate was seen to be 52% in total and 70% for patients in stage C. The modality of radiotherapy for prostate cancer is discussed.

Adenocarcinoma↗
PubMed1997

[Fast neutrons in the treatment of malignant neoplasms].

More than 250 patients, mainly with locally advanced tumors of the head, neck and breast were treated with a I MeV beam of fast neutrons emitted from a BR-10 reactor. The fast neutron contribution to the total dose of the radical component of complex gamma-neutron therapy was 20-40%. Said modality was shown to improve the results of treatment for laryngeal and breast tumors. The 5-year actuarial survival following complex gamma-neutron therapy for laryngeal cancer was 89.25, while in controls--65.2% (p < 0.005). The 5-year actuarial overall survival in breast cancer patients treated with fast neutrons was 66.5%: gamma-neutron therapy alone--46.0% (p < 0.05).

Breast Neoplasms↗
PubMed1990

Status report of fast neutron therapy in the Department of Radiotherapy at the University Hospital Hamburg-Eppendorf.

Since 1976 710 patients were treated with fast neutrons at the University Hospital Hamburg-Eppendorf. Since January 1984 154 patients with soft tissue sarcomas (250 patients with soft tissue sarcomas since 1976), 20 patients with advanced and low grade tumors of the paranasal sinuses and 43 patients with adenoid cystic carcinomas were treated with fast neutrons. Our results and reports from several centers indicate a gain from fast neutron therapy for low grade soft tissue sarcomas, osteosarcomas (G1 and G2), for highly differentiated salivary gland tumors, and some other rare low grade tumors as malignant chordomas, chondrosarcomas, pencil gliomas or desmoid tumors.

Adult↗
PubMed2004

Use of D-T-produced fast neutrons for in vivo body composition analysis: a reference method for nutritional assessment in the elderly.

Body composition has become the main outcome of many nutritional intervention studies including osteoporosis, malnutrition, obesity, AIDS, and aging. Traditional indirect body composition methods developed with healthy young adults do not apply to the elderly or diseased. Fast neutron activation (for N and P) and neutron inelastic scattering (for C and O) are used to assess in vivo elements characteristic of specific body compartments. Non-bone phosphorus for muscle is measured by the (31)P(n, alpha)(28)Al reaction, and nitrogen for protein via the (14)N(n,2n)(13)N fast neutron reaction. Inelastic neutron scattering is used to measure total body carbon and oxygen. Body fat is derived from carbon after correcting for contributions from protein, bone, and glycogen. Carbon-to-oxygen ratio (C/O) is used to measure the distribution of fat and lean tissue in the body and to monitor small changes of lean mass. A sealed, D-T neutron generator is used for the production of fast neutrons. Carbon and oxygen mass and their ratio are measured in vivo at a radiation exposure of less than 0.06 mSv. Gamma-ray spectra are collected using large BGO detectors and analyzed for the 4.43 MeV state of carbon and 6.13 MeV state of oxygen, simultaneously with the irradiation. P and N analysis by delayed fast neutron activation is performed by transferring the patient to a shielded room equipped with an array of NaI(Tl) detectors. A combination of measurements makes possible the assessment of the "quality" of fat-free mass. The neutron generator system is used to evaluate the efficacy of new treatments, to study mechanisms of lean tissue depletion with aging, and to investigate methods for preserving function and quality of life in the elderly. It is also used as a reference method for the validation of portable instruments of nutritional assessment.

Adult↗
PubMed1998

Apoptosis induced by fast neutrons versus 60Co gamma-rays in human peripheral blood lymphocytes.

PURPOSE: To investigate the effectiveness of high LET fast neutrons compared with low LET 60Co gamma-rays to induce apoptosis in resting lymphocytes. MATERIALS AND METHODS: Apoptosis induction was quantified by light microscopic analysis of irradiated lymphocyte samples from healthy donors after 24 h culture. For the dose-response analyses doses ranging from 0.05 to 5 Gy were applied at 1.5 Gy/min (gamma-rays) or 0.2 Gy/min (fast neutrons). To investigate the role of DNA repair in apoptosis induction a dose of 2 Gy was also given at low dose-rate (0.006 Gy/min). RESULTS: Dose-response curves obtained with both radiation qualities were characterized by an initial steep increase in the number of apoptotic cells below 1 Gy, with a flattening of the curves at higher doses towards 5 Gy. The calculated relative biological effectiveness (RBE) values for fast neutrons were close to unity. When a 2 Gy dose was administered at low rather than high dose-rate no decrease in apoptotic cell yield was observed. CONCLUSION: The dose-response data confirm the high radiosensitivity of lymphocytes and demonstrate that their response to undergo early interphase cell death by apoptosis is largely independent of LET. The observations that apoptosis induction is independent of LET and dose-rate may suggest that initial DNA damage, as opposed to DNA repair, dominate the induction of apoptosis in resting lymphocytes.

Adult↗
PubMed1986

Microdosimetric investigation of a fast neutron radiobiology facility utilising the d(4)-9Be reaction.

For fast neutron therapy and radiobiology beams, knowledge of the primary neutron spectrum is the most fundamental requirement for the definition of radiation quality. However, microdosimetric measurements in the form of single-event spectra not only complement the primary neutron spectrum as a statement of radiation quality but also provide a sensitive method of detecting changes in the radiation field in situations where it is no longer possible to have precise knowledge of the primary neutron spectrum, for example after collimator changes and in positions where the radiation field consists of a large scattered component. For the various collimator arrangements employed at the Gray Laboratory facility small perturbations of the radiation field are observed which can be related to a softening of the primary neutron spectrum with increasing field size of the collimator. Gamma fraction determinations are in very good agreement with measurements employing the dual chamber technique and also show small changes with collimator field size giving rise to gamma components ranging from 0.09 to 0.12, the higher values being measured for the larger field sizes. Quality changes represented by the shape of the measured event-size spectra and the derived microdosimetric parameters were greatest for off axis and phantom measurements. With increasing depth in water, yD was found to decrease from 47.3 keV micron-1 at 5 cm to 35.6 keV micron-1 at 15 cm depth, and the gamma fraction was found to increase from 0.23 to 0.40. Although there is no generally accepted and agreed method of relating microdosimetric information to biological effectiveness, the dual radiation theory in its original form (Kellerer and Rossi 1972) has been shown to be a very useful model for the assessment of the biological effectiveness of fast neutrons (Kellerer et al 1976). The microdosimetric parameter which is used in the dual radiation model is the dose mean specific energy corrected for saturation zeta* which, for a 2 micron simulated diameter, is related to the dose mean lineal energy corrected for saturation y* by zeta* = y* keV micron-1 X 0.51 X 10(-2) Gy. Values of y* determined for each of the collimator arrangements used at the Gray Laboratory show a spread of some 6% (table 1) and, as the dose fraction between lineal energies 5 and 150 keV micron-1 (the recoil proton component) do not alter by more than 3%, radiobiological experiments performed with different collimator arrangements would show no observable differences.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1994

Development of fast neutron therapy worldwide. Radiobiological, clinical and technical aspects.

Radiobiological data indicate that fast neutrons could bring a benefit in the treatment of some tumour types, and suggest mechanisms through which this benefit could be achieved. However, radiobiology also clearly indicates that there is a need for patient selection as well as for a high-physical selectivity. The main difficulty when interpreting the results of neutron therapy are the poor technical conditions in which the first treatments were applied. This explains why the value and the place of neutron therapy are not universally recognized, although more than 15,000 patients have been treated so far worldwide. There are, however, clinical indications of fast neutrons bringing a benefit for the following tumour sites: salivary glands, paranasal sinuses, soft tissue sarcomas, prostatic adenocarcinomas, palliative treatment of melanoma and rectum. These tumours represent about 10-15% of all patients currently referred to the radiation therapy departments.

Academies and Institutes↗
PubMed1994

[Fast neutron treatment of osteosarcoma].

Twelve patients with advanced osteosarcoma were treated with fast neutron at the Neutron Therapy Facility, the Hight-Energy Physics Institute, Chinese Academy of Science. Of the 12 patients, 5 were operated after radiotherapy. Three of them received fast neutron alone, and the other 2 with added 60Co. The doses ranged from 660 NcGy to 2 168 NcGy. Pain was relieved and the tumor size decreased in all the treated patients. Only one case was found histologically free of viable tumor cells. Skin reaction was serious and the knee joint function was impaired in all patients.

Adolescent↗
PubMed1976

Adenocarcinoma of the stomach: radiological and pathological correlation of effects of treatment with fast neutrons.

During the past six years 40 patients have been treated with fast neutrons for inoperable adenocarcinoma of the stomach. A number of these patients have been studied in detail both radiologically and pathologically with regard to the effects of fast neutrons on both the tumour and normal stomach. After treatment there was a constant reduction in size of the stomach capacity when compared with a control group and the motility of the stomach was lost. Mucosal changes, which were noted radiologically, appeared to be dose related. Histologically most of the tumour was destroyed. Small clumps of cells were, however, found in all except one of the patients but only in areas of the stomach which had not received the standard dose. Marked fibrosis occurred and it is our impression that the amount of fibrosis is in excess of that seen with other forms of radiotherapy.

Adenocarcinoma↗
PubMed1982

Effect of irradiation with fast neutrons or X-rays on the incidence of metastasis of transplanted B16 melanoma in mice.

The effects of X-rays and fast neutrons on the incidence of metastasis of B16 melanoma were investigated. Tumors were irradiated with the iso-effect dose (380 rad of 2 MeV fast neutrons, and 1900 rad of 200 kV X-rays) for regression and regrowth of the tumor, and then were excised 3 days after irradiation. Metastasis was examined macroscopically and microscopically in all organs and tissues of mice when death occurred or after sacrifice of surviving mice at 130 days after tumor inoculation. Metastasis was found in 16 to 22% of tumor-bearing mice irrespective of whether or not the tumor had been irradiated before excision. Almost all the mice with metastasis developed pulmonary metastasis accompanied by lymphogenous spread to the thoracic lymph node. The overall incidence of metastasis in the X- or fast neutron-irradiated mice was slightly but not significantly higher than that in the control mice. Irradiation significantly enhanced the incidence of metastasis when the tumor volume was smaller than 200 mm3, but not when the tumor volume was larger than 200 mm3. The incidence of metastasis was significantly enhanced in mice with tumors invading the muscle. The metastasis-enhancing effect of irradiation was noticeably greater with X-irradiation than with fast neutron irradiation in mice with localized tumors of B16 melanoma, whereas in mice with invasive tumors the effects were similar.

Animals↗
PubMed1989

Present status of fast neutron therapy in Asian countries.

The present status of the treatment with fast neutrons performed in Asian countries is reviewed and the experiences with respect to the radiobiological indications are presentated and discussed. There are three facilities under operation, the National Institute of Radiological Sciences (NIRS) in Chiba, the Institute of Medical Science (IMS) in Tokyo and the Korea Cancer Center Hospital (KCCH) in Seoul. The clinical experiences can be summarized as follows: Fast neutrons are the treatment of choice for carcinoma of the salivary gland, Pancoast tumor of the lung, osteosarcoma, soft tissue sarcoma and malignant melanoma. Provided the isodose planning can be improved, it seems that also squamous cell carcinoma of the head and neck and esophagus, adenocarcinoma of the lung, stage I and prostatic adenocarcinoma can be benefit from neutron therapy. The same holds for malignant meningioma, while the benefit for glioblastoma multiforme has not yet been confirmed. Studies are going on for the treatment of other cancers and for evaluating the possible role of neutron therapy in combination with surgery.

Cancer Care Facilities↗
PubMed1992

Detection system for measuring dose equivalent from fast neutrons in mixed gamma-neutron fields.

A hybrid detector for measuring fast neutrons in mixed gamma-neutron fields is discussed in this paper. The detector consists of an ionization chamber with components made from a plastic scintillator. Its operation is based on the two detection systems thus combined. Its parameters and domain of applicability are explained. This paper proposes a rapid integral method for measuring the neutron-dose equivalent based on this detector, which allows a good separation of the gamma component.

Fast Neutrons↗