[en] The methodology we have developed to study dose distribution outside the target volume during external beam radiotherapy allows us to determine the dose received by the patient arising from leakage radiation and scattered radiation from both the head of the treatment machine and from the treatment room. It also allows us to evaluate the dose due to photon scattering in the patient by means of a dedicated 3-D algorithm permitting computations for the whole body of the patient and taking into account height, sex and anatomical data at the time of the treatment, dosimetric data and lung heterogeneity parameters. This methodology offers solid criteria for recommendations concerning radiation protection

[en] Results of a cohort study designed to evaluate the long term risk of thyroid tumours after fractioned high doses of external beam radiotherapy received by the thyroid are reported. In this cohort study, doses have been estimated for each child. (author)

[en] Between 1954 and 1983, 7620 patients were treated for breast carcinoma at Institut Gustave Roussy (France). Of these patients, 6919 were followed for at least 1 year. Out of these, 11 presented with sarcomas thought to be induced by irradiation, 2 of which were Steward-Treves Syndrome, and 9 of which were sarcomas within the irradiated fields. All histological slides were reviewed and a comparison with those of breast cancer was done. The sites of these sarcomas were: parietal wall, 1 case; second costal cartilage, 1 case; infraclavicular region, 1 case; supraclavicular region, 2 cases; internal third of the clavicle, 2 cases; axillary region 2 cases; and the internal side of the upper arm (Stewart-Treves syndrome), 2 cases. The median age of these 11 patients at the diagnosis of sarcomas was 65.8 (49-83). The mean latent period was 9.5 years (4-24). Three patients underwent radical mastectomy and nine modified radical mastectomy. Only one patient received chemotherapy. The radiation doses received at the site of the sarcoma were 45 Gy/18 fr. for 10 cases and 90-100 Gy for 1 case (due to overlapping between two fields). The histology was as follows: malignant fibrous histiocytoma, 5 cases; fibrosarcoma, 3 cases; lymphangiosarcoma, 2 cases; and osteochondrosarcoma, 1 case. The median survival following diagnosis of sarcoma was 2.4 years (4 months-9 years). Two patients are still alive: one with recurrence of her breast cancer, the other in complete remission, with 7 and 3 years follow-up, respectively. All other patients died from their sarcomas. The cumulative incidence of sarcoma following irradiation of breast cancer was 0.2% (0.09-0.47) at 10 years. The standardized incidence ratio (SIR) of sarcoma (observed n number-sign of cases (Obs)/expected n number-sign of cases (Exp) computed from the Danish Cancer Registry for the same period) was 1.81 (CI 0.91-3.23)

[en] Short communication

[en] The frequency of thyroid nodules has been studied among 396 children irradiated for a hemangioma, from 1946 to 1973, ²²⁶Ra, ¹⁹²Ir, ⁹⁰Y, ³²P, ⁹⁰Sr, as well as X-rays had been used for treatments. The doses of radiation received by the thyroid of each child have been estimated retrospectively. The irradiations have been classified in two categories based on their duration: less than 30 min., and more than 30 min. The doses received with each of these two types of irradiation were summed for each patient. The risk of thyroid nodule increased as a function of the dose to thyroid only for the dose delivered with the short duration. This study emphases the importance of the role of the dose rate in the risk of radio-induced tumour

[en] Retrospective dosimetry in large cohorts of medically exposed patients is essential to investigate the relationship between the dose delivered and the corresponding risk of cancer incidence over the lifetime. The estimation of doses in such studies is characterised by the poor availability and large diversity of data for the patients geometry, treatment modalities, and anatomical sites of interest. We have developed, at the Institut Gustave Roussy (IGR), two theoretical models (ICTA) and (Dos EG), flexible enough to allow their use in such diverse situations and also robust enough to allow further developments if needed. Both models are well designed to estimate the absorbed doses at numerous sites (151 anatomical points) for every patient in the cohort, and are easily handled. To simulate the patient at the time of treatment, both models use the geometrical parameters of the auxological tables (representing the mean French population). The ICTA model has been adapted to the technical characteristics of the applicators (Ra-226, Sr-90/Y-90, P-32, Y-90) that were used at the IGR for the treatment of skin hemangiomas, and has been used in a European study to evaluate dose-response relationships for radiation induced cancer. The Dos EG model has been adapted to actual treatment techniques used for external radiotherapy in different treatment centres, including various beam qualities from different machines (Cobalt, linear accelerators, betatrons, and orthovoltage tubes). It has been used to study the risk of second cancer following radiotherapy for a solid cancer in a cohort of 4400 children, and following a breast cancer in a cohort of 800 women. (author)

[en] Radiation doses outside the radiotherapy treatment field are of radiation protection interest. Available studies investigating such doses, focused on specific sites, standard target volumes, and a few radiation beams or treatment conditions. We present a software package designed to perform individual dosimetry in retrospective studies. It was developed for a European cohort study of over 4400 patients who were younger than 17 years when treated for a primary solid cancer in childhood at 8 French and UK cancer centres. The methodology adopted by this software enabled the anatomical data for all patients in the cohort who were between a few days to 16 years of age, to be taken into account. It includes the characteristics of all machines used to treat the patients from 1942 to 1992. The absorbed doses are estimated directly in volum% and the lung heterogeneity is considered. Based on actual measurements, all principal sources of scattered radiation, sources of doses to out-of-beam sites, are modelled and introduced. For each patients, absorbed doses to 151 anatomical sites were calculated, according to radiation beam energy with a range of energy from 50 kV to 31 MV for photons and 4 to 32 MeV for electrons. Such a tool can provide dose estimation sufficiently accurate for radiation protection purposes. (author)

[en] Background and purposes: The individual dosimetry performed for a multicentre European cohort study of second malignant neoplasm following radiotherapy for a solid cancer in childhood demonstrated a large variation in the radiation doses estimated to any site. Materials and methods: From this study we have extracted the present work, i.e. estimation of doses for patients who underwent radiotherapy for Hodgkin's disease in their childhood. These patients were treated using high energy X-rays from linear accelerators (MV group), γ-radiation from Cobalt machines (Cobalt group), soft X-rays from orthovoltage machines (kV group) and electron beams from accelerators (MeV group) at six French and UK centres. All patients started their radiotherapy between 1955 and 1985 and about 12% of them received more than one beam quality. Most of the patients were irradiated with large mantle AP/PA or partial mantle fields. Patients with transdiaphragmatic extension were also irradiated using inverted-Y paraaortic fields. The absorbed doses at the 91 skeleton points are used to calculate the mean dose to the active bone marrow. Results: Estimates of the median and mean doses, standard deviations and ranges to 13 specific sites of the body and to the active bone marrow are reported. Depending upon the size and sex of patients, target volume and position and radiotherapy techniques, the estimated doses are highly spread, attaining 0.19-106.07% of the target dose. This study underscores the need for individual dosimetry in epidemiological studies. Comparison with the available measured and calculated doses to the ovary and testis shows good agreement. Conclusion: This study underscores the need for individual dosimetry in epidemiological studies. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

[en] Full text of publication follows: In spite of the improvements in treatment techniques, radiotherapy always involves unwanted irradiation of healthy organs and tissues. Our aim was to quantify the dose to the site of the second malignant neoplasm (S.M.N.) development. The study focused on 155 patients with S.M.N. among a cohort of 4,581 individuals, at least 2-year survivors, treated between 1942 and 1986, for a solid cancer during childhood in 8 centres in France and Great Britain. The software package Dos-EG was used to estimate the radiation doses. Concepts introduced by the International Commission on Radiation Units and Measurements about the volumes were used to specify relative doses. Thus, we were able to determine the relative position of S.M.N. development with respect to the target volume. About 25% of S.M.N. occurred in sites where the estimated radiation dose was lower than 0.9 Gy and 35 % in sites where doses were lower than 5 Gy. The median dose to the site of origin of S.M.N. was about 12.9 Gy (range: 0 -73 Gy). Among all cases, 19.13 % occurred within the treated volume enclosed in the 95 % isodose surface, 25.22 % within the irradiated volume between the 95% and 50 % isodose surfaces, 35.65 % in the penumbra region between the 50 % and 20 % isodose surfaces, and 20.00 % were beyond the penumbra region. With the introduction of sophisticated treatment techniques such as intensity modulated radiotherapy, both treated volume and irradiated volume are reduced but the volume receiving low doses is substantially enlarged. This study showed that a notable fraction of S.M.N. occurred in regions where the dose received is lower than 5 Gy. These results should be considered when assessing whether the benefit of the treatment is higher than the risk. (authors)

[en] The pattern of the temporal distribution of solid cancer incidence after irradiation in childhood is not well known, although, its importance in radioprotection is well known. We studied a cohort of 1 055 children from 8 European cancer centres, who received radiotherapy between 1942 and 1985 for a first cancer in childhood. After a mean follow-up of 19 years, 26 children developed a solid second malignant neoplasm (SMN), as compared to 5.6 expected from general population rates. Both the excess relative risk and the excess of absolute risk of solid SMN were higher among children who were younger at time of the irradiation. After reaching a maximum 15 to 20 years after irradiation, the excess relative risk of SMN decreased with time after irradiation, when controlling for age at irradiation and sex. The analysis of the risk of thyroid, brain and breast cancer together, as a function of the dose averaged on these 3 organs lead to similar results. (authors). 16 refs., 8 tabs., 2 figs