Thyroid volume measurement in external beam radiotherapy patients using CT imaging: correlation with clinical and anthropometric characteristics.

The aim of this study is to define criteria for accurate representation of the thyroid in human models used to represent external beam radiotherapy (EBRT) patients and evaluate the relationship between the volume of this organ and clinical and anthropometric characteristics. From CT images, we segmented the thyroid gland and calculated its volume for a population of 188 EBRT patients of both sexes, with ages ranging from 1 to 89 years. To evaluate uncertainties linked to measured volumes, experimental studies on the Livermore anthropomorphic phantom were performed. For our population of EBRT patients, we observed that in children, thyroid volume increased rapidly with age, from about 3 cm(3) at 2 years to about 16 cm(3) at 20. In adults, the mean thyroid gland volume was 23.5 ± 9 cm(3) for males and 17.5 ± 8 cm(3) for females. According to anthropometric parameters, the best fit for children was obtained by modeling the log of thyroid volume as a linear function of body surface area (BSA) (p < 0.0001) and age (p = 0.04) and for adults, as a linear function of BSA (p < 0.0001) and gender (p = 0.01). This work enabled us to demonstrate that BSA was the best indicator of thyroid volume for both males and females. These results should be taken into account when modeling the volume of the thyroid in human models used to represent EBRT patients for dosimetry in retrospective studies of the relationship between the estimated dose to the thyroid and long-term follow-up data on EBRT patients.

Individual radiation therapy patient whole-body phantoms for peripheral dose evaluations: method and specific software.

This study presents a method aimed at creating radiotherapy (RT) patient-adjustable whole-body phantoms to permit retrospective and prospective peripheral dose evaluations for enhanced patient radioprotection. Our strategy involves virtual whole-body patient models (WBPM) in different RT treatment positions for both genders and for different age groups. It includes a software tool designed to match the anatomy of the phantoms with the anatomy of the actual patients, based on the quality of patient data available. The procedure for adjusting a WBPM to patient morphology includes typical dimensions available in basic auxological tables for the French population. Adjustment is semi-automatic. Because of the complexity of the human anatomy, skilled personnel are required to validate changes made in the phantom anatomy. This research is part of a global project aimed at proposing appropriate methods and software tools capable of reconstituting the anatomy and dose evaluations in the entire body of RT patients in an adapted treatment planning system (TPS). The graphic user interface is that of a TPS adapted to obtain a comfortable working process. Such WBPM have been used to supplement patient therapy planning images, usually restricted to regions involved in treatment. Here we report, as an example, the case of a patient treated for prostate cancer whose therapy planning images were complemented by an anatomy model. Although present results are preliminary and our research is ongoing, they appear encouraging, since such patient-adjusted phantoms are crucial in the optimization of radiation protection of patients and for follow-up studies.

Radiation dose as a risk factor for malignant melanoma following childhood cancer.

The aim of this study was to determine therapy-related risk factors for the development of melanoma after childhood cancer. Among 4401 3-year survivors of a childhood cancer in eight French and British centres and 25120 patients younger than 20 years old at first malignant neoplasm (FMN) extracted from the Nordic Cancer Registries, 16 patients developed a melanoma as a second malignant neoplasm (SMN). A cohort study of the French and British cohorts was performed. In a nested case-control study, the 16 patients who developed a melanoma as a SMN (cases) were matched with 3-5 controls in their respective cohort according to gender, age at the first cancer, the calendar year of occurrence of the first cancer and follow-up. Radiotherapy appeared to increase the risk of melanoma for local doses >15 Gy, Odds Ratio (OR)=13 (95% Confidence Interval (CI): 0.94-174). Regarding chemotherapy, we observed an increased OR for both alkylating agents and spindle inhibitors, OR=2.7 (95% CI: 0.5-14). Children treated for a gonadal tumour as a FMN were found to be at a higher risk of melanoma, OR=8.7 (95% CI: 0.9-86). The adjusted OR for the local radiation dose was 1.07 (95% CI: 1.00-1.15). In conclusion, radiotherapy may contribute to an increased risk of melanoma as a SMN, but only at very high doses of low linear energy transfer radiation. Common genetic origins between gonadal tumours and malignant melanomas are likely.

Optimizing the use of LiF:Mg,Cu,P (GR-200 P) to measure low dose irradiation in nuclear medicine.

We undertook a study in order to determine the optimal conditions under which thermoluminescent powder LiF:Mg,Cu,P (GR-200 P) could be used for applications in nuclear medicine and for dosimetric needs. First, we defined the conditions chiefly related to the readout chain, namely the optimal mass of GR-200 material used for each readout, which is between 15 and 30 mg, and the optimal glow curve readout, which corresponds to heating in two phases: a rise in temperature at the rate of 10 degrees C s(-1) up to 150 degrees C followed by a plateau lasting 10 s and then another rise in temperature at the rate of 25 degrees C s(-1) up to 260 degrees C followed by a second plateau lasting 6 s. The optimum conditions for using TL material were also studied: using GR-200 P without annealing and performing two successive readouts of the same sample only led to a 0.1% loss in sensitivity per re-use cycle, and the good reproducibility of measurements was preserved with stable and weak residual TL signal. The response of the sample irradiated at three different dose levels with a 60Co gamma photon beam remained constant over 40 d. Sensitivity was preserved to within +/-4% between a few tenths of a microGy and 1 Gy. Our observations concur with the results of the literature and show how to optimize the conditions for using the GR-200 thermoluminescent dosimeter to measure low doses with a simple procedure that preserves the sensitivity of material.

[Definition of volumes in external radiotherapy: ICRU reports 50 and 62]. / Définition des volumes en radiothérapie externe: rapports ICRU 50 et 62.

Prescribing and achieving radiotherapy require accurate definitions of the target volumes and of the dose to be delivered in them. The need for the availability of a coherent vocabulary, recognized from local to international levels, has justified the publication, by the ICRU, of two reports related to external radiotherapy, the Report 50 (1993) and the Report 62 (1999). This paper presents the main propositions of the ICRU for the definition of the volumes, as well as comments and recommendations for their use.

The ESTRO-EQUAL Quality Assurance Network for photon and electron radiotherapy beams in Germany.

BACKGROUND: In 1998 an ESTRO Quality Assurance Network for radiotherapy (EQUAL) has been set up for 25 European countries for photon and electron beams in reference and non-reference conditions. MATERIAL AND METHODS: Measurements are done using LiF powder (DTL937-Philitech, France) that is processed with the PCL3 automatic reader (Fimel-PTW). The participating centers irradiate the TLDs with an absorbed dose of 2 Gy according to the clinical routine. RESULTS: Until September 2000 EQUAL has checked 135 photon beams (including the beams rechecked) from 51 radiotherapy centers in Germany out of 86 accepted centers. The results show that 2% of the beam outputs in reference conditions and 3% of the percentage depth doses are outside the tolerance level (deviation > +/- 5%). 6% of the beam output variations and of the wedge transmission factors show deviations > +/- 5%. The global analysis of results shows deviations > +/- 5% in at least one parameter for 18 beams out of the 135 beams checked. Five rechecked beams present one "real dosimetric" problem in one or more parameters, corresponding to 4% of the 114 beams for which the deviations cannot be attributed to set-up errors.--The EQUAL network has checked 89 electron beams in Germany. The results show that all beam outputs checked are within the tolerance level. The standard deviation for the beam output in reference conditions is 2.0% and 2.2% for the beam output for the others field sizes. The percentage of deviations > 3% and < or = 5% for the reference beam output is higher for electron beams than for photon beam checks. Therefore the electron beam calibration and the TPS algorithms should be improved to increase the accuracy of the patient dosimetry for radiotherapy. CONCLUSION: EQUAL program demonstrates a consistency in radiotherapy dosimetry for photon and electron beams resulting in a satisfying accuracy of the dosimetry in Germany.

Estimation of the radiation dose from radiotherapy for skin haemangiomas in childhood: the ICTA software for epidemiology.

Radium applicators and pure beta emitters have been widely used in the past to treat skin haemangioma in early childhood. A well defined relationship between the low doses received from these applicators and radiation-induced cancers requires accurate dosimetry. A human-based CT scan phantom has been used to simulate every patient and treatment condition and then to calculate the source target distance when radium and pure beta applicators were used. The effective transmission factor psi(r) for the gamma spectrum emitted by the radium sources applied on the skin surface was modelled using Monte Carlo simulations. The well-known quantization approach was used to calculate gamma doses delivered from radium applicators to various anatomical points. For 32P, 90Sr/90Y applicators and 90Y needles we have used the apparent exponential attenuation equation. The dose calculation algorithm was integrated into the ICTA software (standing for a model that constructs an Individualized phantom based on CT slices and Auxological data), which has been developed for epidemiological studies of cohorts of patients who received radium and beta-treatments for skin haemangioma. The psi(r) values obtained for radium skin applicators are in good agreement with the available values in the first 10 cm but higher at greater distances. Gamma doses can be calculated with this algorithm at 165 anatomical points throughout the body of patients treated with radium applicators. Lung heterogeneity and air crossed by the gamma rays are considered. Comparison of absorbed doses in water from a 10 mg equivalent radium source simulated by ICTA with those measured at the Radiumhemmet, Karolinska Hospital (RAH) showed good agreement, but ICTA estimation of organ doses did not always correspond those estimated at the RAH. Beta doses from 32P, 90Sr/90Y applicators and 90Y needles are calculated up to the maximum beta range (11 mm).

Energy correction factors of LiF powder TLDs irradiated in high-energy electron beams and applied to mailed dosimetry for quality assurance networks.

Absorbed dose determination with thermoluminescent dosimeters (TLDs) generally relies on calibration in 60Co gamma-ray reference beams. The energy correction factor fCo(E) for electron beams takes into account the difference between the response of the TLD in the beam of energy E and in the 60Co gamma-ray beam. In this work, fCo(E) was evaluated for an LiF powder irradiated in electron beams of 6 to 20 MeV (Varian 2300C/D) and 10 to 50 MeV (Racetrack MM50), and its variation with electron energy, TLD size and nature of the surrounding medium was also studied for LiF powder. The results have been applied to the ESTRO-EQUAL mailed dosimetry quality assurance network. Monte Carlo calculations (EGS4, PENELOPE) and experiments have been performed for the LiF powder (rho = 1.4 g cm3) (DTL937, Philitech, France), read on a home made reader and a PCL3 automatic reader (Fimel, France). The TLDs were calibrated using Fricke dosimetry and compared with three ionization chambers (NE2571, NACP02, ROOS). The combined uncertainties in the experimental fCo(E) factors determined in this work are less than about 0.4% (1 SD), which is appreciably smaller than the uncertainties up to 1.4% (1 SD) reported for other calculated values in the literature. Concerning the Varian 2300C/D beams, the measured fCo(E) values decrease from 1.065 to 1.049 +/- 0.004 (1 SD) when the energy at depth in water increases from 2.6 to 14.1 MeV; the agreement with Monte Carlo calculations is better than 0.5%. For the Racetrack MM50 pulsed-scanned beams, the average experimental value of fCo(E) is 1.071 +/- 0.005 (1 SD) for a mean electron energy at depth Ez ranging from 4.3 to 36.3 MeV: fCo(E) is up to 2% higher for the MM50 beams than for the 2300C/D beams in the range of the tested energies. The energy correction factor for LiF powder (3 mm diameter and 15 mm length) varies with beam quality and type (pulsed or pulsed-scanning), cavity size and nature of the surrounding medium. The fCo(E) values obtained for the LiF powder (3 mm diameter and 15 mm length) irradiated in water, have been applied to the EQUAL external audit network, leading to a good agreement between stated and measured doses, with a mean value of 1.002 +/- 0.022 (1 SD), for 170 beam outputs checked (36 electron beam energies) in 13 'reference' radiotherapy centres in Europe. Such fCo(E) data improve the accuracy of the absorbed dose TLD determination in electron beams, justifying their use for quality control in radiotherapy.

The ESTRO-QUALity assurance network (EQUAL).

BACKGROUND AND PURPOSE: ESTRO has set up a Quality Assurance network (EQUAL) to check the dose delivered on axis in reference and non-reference conditions for external radiotherapy. The external audits covered by the network are based on measurements made with mailed thermoluminescent dosimeters (TLD). MATERIAL AND METHODS: The TLD consist of LiF powder type DTL 937 read with a PCL 3 automatic TLD reader. The participating centres are instructed to deliver to the TLDs absorbed doses of 2 Gy calculated with the Treatment Planning System used in clinical routine. A maximum of three photon energies by participating centre have been checked with 10 on-axis points per beam. The quantities checked include the reference beam output, beam output variation with collimator opening, depth dose data and wedge transmission factor. RESULTS: During the 1998 EQUAL programme 102 centres have been checked corresponding to 235 beams (28 (60)Co beams and 207 X-ray beams). About 3% of the outputs in reference conditions show deviations outside tolerance level (>+/-5%). A similar rate of deviation is noted for the percentage depth doses. A rate of deviation (6%) has been observed for the beam output variation (open and wedged beams) and the wedge transmission factor. The analysis of the results shows that for 24 out of the 102 centres, a deviation outside tolerance level is observed at least in one point, mainly for the large and rectangular field sizes and for the wedged beams. CONCLUSIONS: The results for the EQUAL programme show the importance of a quality assurance network in Radiotherapy especially for the non reference points even if they are only located on the beam axis (In order to participate in this network, please contact EQUAL secretariat or download the attached application form ESTRO web site: Dr I.H. Ferreira or Mrs Aline Mechet, EQUAL-ESTRO, Physics Department, Institut Gustave-Roussy 39 Rue Camille Desmoulins, F-94805 Villejuif Cedex, France. e-mail:equal@igr.fr or http://www.estro.be/).

Clinical impact of dosimetry quality assurance programmes assessed by radiobiological modelling of data from the thermoluminescent dosimetry study of the European Organization for Research and Treatment of Cancer.

The European Organization for Research and Treatment of Cancer (EORTC) Radiotherapy Group initiated its mailed thermoluminescence dosimetry (TLD) programme in 1986. The aim of the present study was to evaluate the clinical relevance of variations in beam output detected in the period 1993 to 1996. A total of 140 beam outputs were checked (26 for cobalt-60 units and 114 for linear accelerators) in 35 centres. Clinical dose-response data for tumour control and normal tissue morbidity were used to assess the variation in clinical outcome resulting from variability in beam output. For 75 checked beams with nominal accelerating potentials (n. a.p.) of 6 MV or less the mean ratio, +/- standard deviation (S.D.) of measured to stated output was 1.004+/-0.020. For 65 beams with n. a.p. of 8 MV or more, the ratio was 1.009+/-0.021. Even with this relatively high level of precision, broad distributions of estimated tumour control or normal tissue morbidity were found. In the 10% of the beams with the most pronounced underdosage, the loss in tumour control probability was estimated at 7-8 percentage points. Likewise, in the 10% of the beams with the most pronounced overdosage, the increase in mild/moderate morbidity was 19-22 percentage points. For severe morbidity the same beams raised the estimated incidence of severe complications from 5% to 9-10%. An estimation of the loss of uncomplicated cure probability was about 1% for both high and low energy beams. Sequential mailings considerably improved the uniformity of clinical outcome. We conclude that small deviations in beam output may lead to clinically important variations in outcome. Substantial reductions in the variation between measured and stated output can be achieved by sequential mailings. Mailed TLD checks should be an integral part of a continuously ongoing quality assurance activity in radiotherapy.

Thyroid carcinomas after irradiation for a first cancer during childhood.

BACKGROUND: The thyroid gland is among the most radiosensitive organs. However, little is known about the long-term risk of developing a thyroid tumor after fractionated external radiotherapy for cancer during childhood. OBJECTIVE: To study the long-term risk of developing a thyroid tumor in 4096 three-year survivors of childhood cancer treated between May 1942 and December 1985 in 8 centers in France and the United Kingdom, 2827 of whom had received external radiotherapy. METHODS: A wide range of radiation doses were given to the thyroid: 1164 children received less than 0.5 Gy and 812 received more than 5.0 Gy, the average dose being 7.0 Gy. RESULTS: After mean follow-up of 15 years (range, 3-45 years), 14 patients-all of whom had received radiotherapy-developed a clinical thyroid carcinoma. Within the cohort, the relation between radiation dose to the thyroid and risk of thyroid carcinoma and adenoma was similar to that observed in patients who received radiotherapy during childhood for other reasons, such as an excess relative risk per gray of 4 to 8, up to a few gray. In contrast, compared with thyroid cancer incidence in the general population, the standardized incidence of thyroid carcinoma was much higher than expected from the dose-response relationship estimated within the cohort and from patients who received radiotherapy during childhood for other reasons: a dose of 0.5 Gy was associated with a standardized incidence ratio of 35 (90% confidence interval, 10-87) and a dose of 3.6 Gy with a standardized incidence ratio of 73 (90% confidence interval, 28-153). We did not show a reduction in excess relative risk per gray with use of an increasing number of fractions. CONCLUSION: Although we cannot estimate the exact proportion, it is probable that some or all children who are treated for cancer are predisposed to developing a thyroid carcinoma.

Monte Carlo calculations of the ionization chamber wall correction factors for 192Ir and 60Co gamma rays and 250 kV x-rays for use in calibration of 192Ir HDR brachytherapy sources.

As in the method for the calibration of 192Ir high-dose-rate (HDR) brachytherapy sources, the ionization chamber wall correction factor A(w), is needed for 192Ir and 60Co gamma rays and 250 kV x-rays. This factor takes into account the variation in chamber response due to the attenuation of the photon beam in the chamber wall and build-up cap and the contribution of scattered photons. Monte Carlo calculations were performed using the EGS4 code system with the PRESTA algorithm, to calculate the A(w) factor for 51 commercial ionization chambers and build-up caps exposed to the typical energy spectrum of 192Ir and 60Co gamma rays and 250 kV x-rays. The calculated A(w) correction factors for 192Ir and 60Co sources and 250 kV x-rays agree very well to within 0.1% with published experimental data (the statistical uncertainty is less than 0.1% of the calculated correction factor value). For the 192Ir sources, A(w) varies from 0.973 to 0.993 and for the 250 kV x-rays the minimum value of A(w) for all chambers studied is 0.983. The calculated A(w) correction factors can be used to calculate the air kerma calibration factor of HDR brachytherapy sources, when interpolative methods are considered, contributing to the reduction in the overall uncertainties in the calibration procedure.

Second malignant neoplasms after a first cancer in childhood: temporal pattern of risk according to type of treatment.

The variation in the risk of solid second malignant neoplasms (SMN) with time since first cancer during childhood has been previously reported. However, no study has been performed that controls for the distribution of radiation dose and the aggressiveness of past chemotherapy, which could be responsible for the observed temporal variation of the risk. The purpose of this study was to investigate the influence of the treatment on the long-term pattern of the incidence of solid SMN after a first cancer in childhood. We studied a cohort of 4400 patients from eight centres in France and the UK. Patients had to be alive 3 years or more after a first cancer treated before the age of 17 years and before the end of 1985. For each patient in the cohort, the complete clinical, chemotherapy and radiotherapy history was recorded. For each patient who had received external radiotherapy, the dose of radiation received by 151 sites of the body were estimated. After a mean follow-up of 15 years, 113 children developed a solid SMN, compared to 12.3 expected from general population rates. A similar distribution pattern was observed among the 1045 patients treated with radiotherapy alone and the 2064 patients treated with radiotherapy plus chemotherapy; the relative risk, but not the excess absolute risk, of solid SMN decreased with time after first treatment; the excess absolute risk increased during a period of at least 30 years after the first cancer. This pattern remained after controlling for chemotherapy and for the average dose of radiation to the major sites of SMN. It also remained when excluding patients with a first cancer type or an associated syndrome known to predispose to SMN. When compared with radiotherapy alone, the addition of chemotherapy increases the risk of solid SMN after a first cancer in childhood, but does not significantly modify the variation of this risk during the time after the first cancer.

[Last ICRU recommendations for the prescription, recording and reporting of external bean therapy]. / Dernières recommandations de l'ICRU pour la prescription, l'enregistrement et le compte rendu de la radiothérapie externe.

Due to the evolution of radiotherapy techniques and equipment, in 1993 the ICRU decided to modify the guidelines that had been published in the ICRU report 29 (1978) in regard to photon beam therapy and to insert them in Report number 50 (1993). Changes that were introduced mainly concerned the prescription, recording and reporting of external beam therapy with photons. While awaiting for the upcoming publication of the report focusing on external beam therapy with electrons, the ICRU decided to publish a supplement to Report 50, as new insights had been gained after discussions with the Nordic Association of Clinical Physicists (NACP). This supplement includes the following: more accurate definitions of the margins allowing the planned target volume to be derived from the clinical target volume, the internal target volume, the expected volume of organs at-risk and the conformity index. All three points will be included in the report focusing on external beam therapy with electrons as well as extensive discussions relating to the implementation of these new recommendations.

Perturbation corrections for flat and thimble-type cylindrical standard ionization chambers for 60Co gamma rays: Monte Carlo calculations.

The use of an ionization chamber for absorbed dose determinations in a medium requires one to take into account perturbation corrections due to the presence of the chamber cavity in the medium. Evaluation of these corrections for perturbation and their variation with depth in the medium has been performed for a flat cylindrical and a cylindrical (thimble-type) ionization chamber placed in a graphite phantom irradiated by a 60Co gamma beam using Monte Carlo calculations (EGS4 system with correlated sampling variance reduction technique). The results of these calculations agree with published experimental and theoretical data to better than 0.18%, with a statistical uncertainty of less than 0.17%.

Risks of brain tumour following treatment for cancer in childhood: modification by genetic factors, radiotherapy and chemotherapy.

A cohort of 4,400 persons treated for various cancers of childhood in France and the UK was followed up over an extended period to assess risks of subsequent brain tumour in relation to the radiotherapy and chemotherapy that the children received for their first cancer. Elevated risks of subsequent brain tumours were associated with first central nervous system (CNS) tumour (two-sided p = 0.0002) and neurofibromatosis (two-sided p = 0.001). There was also elevated brain tumour risk (two-sided p = 0.003) associated with ionising radiation exposure, the risk being concentrated among benign and unspecified brain tumours. The radiation-related risk of benign and unspecified brain tumours was significantly higher than that of malignant brain tumours (two-sided p< or =0.05); there was no significant change of malignant brain tumour risk with ionising radiation dose (two-sided p > 0.2). In general, there were no strong associations between alkylating agent dose and brain tumour risk. The only significant association between brain tumour risk and alkylating agent dose was in relation to compounds used (bleomycin, chloraminophen) that are thought not to deliver substantial doses to the brain; the statistical significance of the trend with dose depended on a single case, and thus must be considered a weak result.

Radiation dose, chemotherapy and risk of osteosarcoma after solid tumours during childhood.

Osteosarcoma is the most frequent second primary cancer occurring during the first 20 years following treatment for a solid cancer in childhood. Using a cohort study of children treated for a solid cancer, we investigated the incidence and etiology of osteosarcoma as a second malignant neoplasm after childhood cancer in a cohort and a case-control study. We analysed the relationship between the local dose of radiation and the risk of osteosarcoma, taking into account chemotherapy received. A cohort study of 4,400 3-year survivors of a first solid cancer during childhood diagnosed in France or the United Kingdom, between 1942 and 1986, revealed 32 subsequent osteosarcomas. In a nested case-control study, we matched 32 cases and 160 controls for sex, type of first cancer, age at first cancer and the duration of follow-up. Parameters studied were the incidence of osteosarcoma, the cumulative local dose of irradiation and the cumulative dose of chemotherapy received by cases and controls. The risk of a osteosarcoma was found to be a linear function of the local dose of radiation (excess relative risk per gray=1.8), and was found to increase with the number of moles of electrophilic agents per square meter but not with other drugs. No interaction was noted between radiotherapy and chemotherapy. Bilateral retinoblastoma, Ewing's sarcoma and soft tissue sarcoma were found to render patients susceptible to a higher risk of developing an osteosarcoma as a second malignant neoplasm. We recommend long-term surveillance of patients who were treated during childhood for bilateral retinoblastoma, Ewing's sarcoma, soft tissue sarcoma, as well as other first cancer treated with radiotherapy plus high doses of chemotherapy, without focusing exclusively on the radiation field.

Individualized phantom based on CT slices and auxological data (ICTA) for dose estimations following radiotherapy for skin haemangioma in childhood.

BACKGROUND AND PURPOSE: Before 1974 about 5000 children were treated by radiotherapy at the Institut Gustave-Roussy (IGR) for a skin haemangioma. A human model whose characteristics are as close as possible to those of the patient at the time of the treatment is necessary to effectuate an accurate retrospective estimation of the radiation doses received at distant organs. METHODS: We have developed a software package which constructs an individualized phantom based on CT slices and auxological data (ICTA) for this purpose. A set of real CT slices is used to produce a 3-D representation of the human body which is then adjusted to fit the dimensions supplied by published auxological data relative to sex and age for each patient. One hundred sixty-one anatomical landmarks of epidemiological interest have been defined inside the phantom for dose estimation. RESULTS: The transverse, frontal and sagittal views of the phantom displayed permit accurate positioning of radioactive applicators. The software calculates the relevant parameters required for dose estimation based on the patient's probable anatomy.

Dose distribution throughout the body from radiotherapy for Hodgkin's disease in childhood.

BACKGROUND AND PURPOSE: 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), gamma-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.

Results of a European randomized trial of Etanidazole combined with radiotherapy in head and neck carcinomas.

PURPOSE: The aim of the study was to evaluate the efficacy and toxicity of Etanidazole, a hypoxic cell sensitizer, combined with radiotherapy in the treatment of head and neck squamous cell carcinoma. METHODS AND MATERIALS: A total of 374 patients from 27 European centers were included in this trial between 1987 and 1990. Treatment was either conventional radiotherapy alone (between 66 Gy in 33 fractions and 74 Gy in 37 fractions, 5 fractions per week), or the same radiotherapy dose plus Etanidazole 2 g/m2, three times weekly for 17 doses. A minimization procedure, balancing for center, site, and T stage (T1-T3 vs. T4) was used for randomization. RESULTS: Among the 187 patients in the Etanidazole group, 82% received at least 14 doses of the drug. Compliance to the radiotherapy protocol was 92% in the Etanidazole group and 88% in the control group; the main cause of deviation was acute toxicity, which was observed at an equal rate in the two treatment groups. Fifty-two cases of Grade 1 to 3 peripheral neuropathy were observed in the Etanidazole group vs. 5 cases, all of Grade 1, in the control group (p < 0.001). The 2-year actuarial loco-regional control rates were 53% in the Etanidazole group and 53% in the control group (p = 0.93), and the overall 2-year survival rates were 54% in each group (p = 0.99). CONCLUSION: Adding Etanidazole to conventional radiotherapy did not afford any benefit for patients with head and neck carcinoma. This study failed to confirm the hypothesis of a benefit for patients with N0-N1 disease, which had been suggested by the results of a previous study (10).