Is coracoclavicular stabilisation alone sufficient for the endoscopic treatment of severe acromioclavicular joint dislocation (Rockwood types III, IV, and V)?

BACKGROUND: The primary objective was to evaluate correlations linking anatomical to functional outcomes after endoscopically assisted repair of acute acromioclavicular joint dislocation (ACJD). HYPOTHESIS: Combined acromioclavicular and coracoclavicular stabilisation improves radiological outcomes compared to coracoclavicular stabilisation alone. MATERIAL AND METHODS: A prospective multicentre study was performed. Clinical outcome measures were pain intensity on a visual analogue scale (VAS), subjective functional impairment (QuickDASH score), and Constant's score. Anatomical outcomes were assessed on standard radiographs (anteroposterior view of the acromioclavicular girdle and bilateral axillary views) obtained preoperatively and postoperatively and on postoperative dynamic radiographs taken as described by Tauber et al. RESULTS: Of 116 patients with acute ACJD included in the study, 48% had type III, 30% type IV, and 22% type V ACJD according to the Rockwood classification. Coracoclavicular stabilisation was achieved using a double endobutton in 93% of patients, and concomitant acromioclavicular stabilisation was performed in 50% of patients. The objective functional outcome was good, with an unweighted Constant's score ≥ 85/100 and a subjective QuickDASH functional disability score ≤ 10 in 75% of patients. The radiographic analysis showed significant improvements from the preoperative to the 1-year postoperative values in the vertical plane (decrease in the coracoclavicular ratio from 214 to 128%, p=10(-6)) and in the horizontal plane (decrease in posterior displacement from 4 to 0mm, p=5×10(-5)). The anatomical outcome correlated significantly with the functional outcome (absolute R value=0.19 and p=0.045). We found no statistically significant differences across the various types of constructs used. Intra-operative control of the acromioclavicular joint did not improve the result. Implantation of a biological graft significantly improved both the anatomical outcome in the vertical plane (p=0.04) and acromioclavicular stabilisation in the horizontal plane (p=0.02). The coracoclavicular ratio on the anteroposterior radiograph was adversely affected by a longer time from injury to surgery (p=0.02) and by a higher body mass index (BMI) (p=0.006). High BMI also had a negative effect on the difference in the distance separating the anterior edge of the acromion from the anterior edge of the clavicle between the injured and uninjured sides, as assessed on the axillary views (p=0.009). CONCLUSION: This study demonstrates that acute ACJD requires stabilisation in both planes, i.e., at the coracoclavicular junction and at the acromioclavicular joint. Coracoclavicular stabilisation alone is not sufficient, regardless of the type of implant used. Implantation of a biological graft should be considered when the time from injury to surgery is longer than 10days. The weight of the upper limb should be taken into account, with 6weeks of immobilisation to unload the construct in patients who have high BMI values. LEVEL OF EVIDENCE: II, prospective non-randomised comparative study.

Prognostic factors to succeed in surgical treatment of chronic acromioclavicular dislocations.

INTRODUCTION: Treatment of chronic acromioclavicular joint dislocation (ACJD) remains a poorly known and controversial subject. Given the many surgical options, it is not always easy to determine which steps are indispensable. METHODS: This article reports a multicenter prospective study. The clinical and radiological follow-up involved a comparative analysis of the preoperative and postoperative data at 1 year, including pain (visual analogue scale), subjective functional incapacity (QuickDASH), and the objective Constant score, as well as a comparative analysis of vertical and horizontal movements measured on simple x-rays. RESULTS: Based on a series of 140 operated ACJDs, we included 24 chronic ACJDs. The mean time to surgery was 46 weeks (range, 1 month to 4 years). The patients' mean age was 41 years, with a majority of males (75%), 72% of whom participated in recreational sports. Professionally, 40% of the subjects had jobs involving manual labor. We noted 40% grade III, 24% grade IV, and 36% grade V injury according to the Rockwood classification. In 92% of cases, coracoclavicular stabilization was provided by a double button implant, reinforced with a biological graft in 88% of the cases. In 29%, millimeters to centimeters of the distal clavicle were resected and acromioclavicular stabilization was associated in 54%. We observed complications in 33% of the cases. At 1 year postoperative, 21 patients underwent clinical and radiological follow-up (87.5%). Only 35% of the patients were satisfied or very satisfied, whereas 100% of them would recommend the operation. Full-time work was resumed in 91% of the cases and all sports could be resumed in 86%. The pre- and postoperative values at 1 year changed as follows: the mean Constant score improved from 61 to 87 (p=0.00002); the subjective QuickDASH score decreased from 41 to 9 (p=0.00002); and radiologically significant reduction of the initial displacement was observed in the vertical plane (p<10(-3)) and the horizontal plane (p=0.022). CONCLUSION: In this study, the favorable prognostic factors found were: time to surgery less than 3 months (p=0.02), associated acromioclavicular stabilization, and postoperative immobilization with a sling extended to 6 weeks. However, resection of the distal clavicle did not influence the final result. LEVEL OF PROOF: Level II prospective non-randomized comparative study.

Optimised z-axis coverage at multidetector-row CT in adults suspected of acute appendicitis.

OBJECTIVE: To compare diagnostic performances of two reduced z-axis coverages to full coverage of the abdomen and pelvis for the diagnosis of acute appendicitis and alternative diseases at unenhanced CT. METHODS: This study included 152 adults suspected of appendicitis who were enrolled in two ethical committee-approved previous prospective trials. Based on scans covering the entire abdomen and pelvis (set L), two additional sets of images were generated, each with reduced z-axis coverages: (1) from the top of the iliac crests to the pubis (set S) and (2) from the diaphragmatic crus to the pubis (set M). Two readers independently coded the visualisation of the appendix, measured its diameter and proposed a diagnosis (appendicitis or alternative). Final diagnosis was based on surgical findings or clinical follow-up. Fisher exact and McNemar tests and logistic regression were used. RESULTS: 46 patients had a definite diagnosis of appendicitis and 53 of alternative diseases. The frequency of appendix visualisation was lower for set S than set L for both readers (89% and 84% vs 95% and 91% by Readers A and B, respectively; p=0.021 and 0.022). The probability of giving a correct diagnosis was lower for set S (68%) than set L (78%; odds ratio, 0.611; p=0.008) for both readers, without significant difference between sets L and M (77%, p=0.771); z-axis coverage being reduced by 25% for set M. CONCLUSION: Coverage from diaphragmatic crus to pubis, but not focused on pelvis only, can be recommended in adults suspected of appendicitis. ADVANCES IN KNOWLEDGE: In suspected appendicitis, CT-coverage can be reduced from diaphragmatic crus to pubis.

Can we improve radiological analysis of osseous lesions in chronic anterior shoulder instability?

Osseous lesions of the glenoid cavity and humeral head are predictive of recurrence after Bankart arthroscopic procedures. The objective of this study was to analyze, for each glenoid and humeral defect plain x-ray criteria of the Instability Severity Index Score (ISIS), two aspects: inter- and intraobserver reliability of their qualitative and quantitative assessment and correlations between positive criteria and their quantitative measurement. Thirty-one medical files were retained for evaluation of the glenoid and 26 for humeral notch assessment. The yes or no response for the ISIS criterion was completed by its quantitative measurement using the Griffiths and Sugaya CT methods for the glenoid and the P/R index calculation on plain x-rays with internal rotation for the Hill-Sachs lesion. Three observers provided two consecutive readings for each criterion. The analysis of the glenoid radiological criterion of the ISIS seems sufficiently reproducible for daily practice. When the evaluation is positive, bone loss is greater than 15%, without a maximum value established. In this study, the analysis of the ISIS humeral notch criterion was not reproducible. It can be improved using the P/R index and should be completed by CT imaging.

[Percutaneous osteosynthesis of lumbar and thoracolumbar spine fractures without neurological deficit: surgical technique and preliminary results]. / Ostéosynthèse percutanée des fractures lombaires et thoracolombaires non neurologiques: technique chirurgicale et résultats préliminaires.

PURPOSE OF THE STUDY: The aim of this work was to study the technique of percutaneous osteosynthesis of lumbar and thoracolumbar spine fractures without neurological deficit and to report preliminary results. MATERIAL AND METHODS: This retrospective study included 15 patients with lumbar or thoracolumbar spine fractures who were treated between January 2004 and January 2006 by percutaneous osteosynthesis. There were seven men and eight women, mean age 36 years (range 16-58 years). The Magerl classification (AO) was A1 (n=4), A2 (n=1), A3 (n=9), B2 (n=1). Levels were T12 (n=1), L1 (n=10), L2 (n=2), L3 (n=1), L4 (n=1). A specific instrument set was used to insert a short fixation using two pedicular screws on either side of the fractured vertebra and two prebent 5.5mm rods introduced with an aiming device. The operation was performed under fluoroscopy. Ten patients wore a removable corset. The upright position was allowed if there were no other injuries. Computed-tomography scans were obtained preoperatively, postoperatively and at two years follow-up. Function was assessed with the Oswestry score. RESULTS: Mean operative time was 108 minutes (range 40-180 minutes). None of the patients with an isolated spinal injury required blood transfusion. Mean hospital stay was 12 days (range 4-28). Results were expressed for 13 patients whose operations were exclusively percutaneous. Mean follow-up was 17 months (range 6-30). The visual analog scale (VAS) was 1.6/10. The mean Oswestry score was 16. Three quarters of the patients resumed their occupational activities. None of the patients was dissatisfied. Mean vertebral kyphosis (VK) improved from 16 to 8.1 degrees , corrected regional angle (CRA) from 12 to 2.5 degrees at last follow-up. Loss of correction at last follow-up was 1.1 degrees for VK and 2.5 degrees for CRA. The rate of pedicle screw malposition was 3.8%. There were no cases of disassembly nor material failure. There were no infections. None of the implants had to be removed. DISCUSSION: Percutaneous osteosynthesis of the spine is technically feasible, but requires considerable experience. Functional and subjective results have been good. The loss of correction at last follow-up has been comparable to that observed with conventional open surgery. This technique is an intermediary method between orthopaedic treatment and conventional surgery. Exact indications must be established. CONCLUSION: Percutaneous osteosynthesis of lumbar and thoracolumbar spine fractures is an attractive therapeutic option. Our results are encouraging. Indications and limitations of this technique must be carefully identified.

Three-dimensional anatomy of the hip in osteoarthritis after developmental dysplasia.

Using radiography and computer tomography (CT) we studied the morphology of 83 hips in 69 Caucasian adults with osteoarthritis secondary to developmental dysplasia of the hip (DDH). A previously published series of 310 hips with primary osteoarthritis was used as a control group. According to the Crowe classification, 33 of the dysplastic hips were graded as class I, 27 as class II and 23 as class III or class IV. The intramedullary femoral canal had reduced mediolateral and anteroposterior dimensions in all groups compared with the control group. Only in Crowe class II hips was the femoral neck-shaft angle increased. The proximal femur had more anteversion in all the developmental dysplasia of the hip groups, ranging from 2 degrees to 80 degrees. Templated measurement of acetabular dimensions for plain radiography closely matched measurements taken by CT. The results of our study confirm the observations previously confined to the Japanese population.

[Arthroscopic repair of full-thickness cuff tears: a multicentric retrospective study of 576 cases with anatomical assessment]. / Réparation arthroscopique des ruptures transfixiantes de la coiffe des rotateurs: étude rétrospective multicentrique de 576 cas avec contrôle de la cicatrisation.

PURPOSE OF THE STUDY: Totally arthroscopic repair of rotator cuff tears is now common practice. The techniques used were evaluated by a retrospective multicentric analysis conducted by the French Society of Arthroscopy. MATERIAL AND METHODS: The series was limited to arthroscopic repair of full thickness tears of the supraspinatus or infraspinatus evaluated using the Constant score and arthro-MRI or arthroscan performed with at least one year follow-up. Data were processed with SPSS 10. The series included 576 patients who underwent surgery between January 2001 and June 2003. Mean patient age was 57.7 years; 52% were men and 60% were manual laborers. The mean preoperative Constant score was 46.4 +/- 13.4/100. The tear was limited to the supraspinatus in 69% of shoulders, with extension to the upper third of the infraspinatus in 23.5% and the entire infraspinatus in 7.5%. The supraspinatus tear was distal in 41.7% of shoulders, intermediary in 44% and retracted in 14.3%. Fatty degeneration of the supraspinatus was noted grade 0 in 60%, 1 in 27%, 2 in 11% and 3 in 2%. Arthroscopic repair was performed in all cases, with locoregional anesthesia in 60.9%. Bioresorbable implants were used in 33% and metallic implants in 62.1%. Acromioplasty was performed in 92.7% and capsulotomy in 14.9%. RESULTS: On average, the subjective outcome was scored 8.89/10. The Constant score improved from 46.3 +/- 13.4 to 82.7 +/- 10.3 with 62% having a strictly pain free shoulder. Muscle force improved from 5.8 +/- 3.7 to 13.6 +/- 5.4. Outcome was excellent in 94% of shoulders at 18.5 months mean follow-up. The complication rate in this series was 6.2% with 3.1% prolonged stiffness, 2.7% reflex dystrophy, 0.2% infection, and 0.2% anchor migration. The cuff was considered normal in 55.7% of shoulders with an intratendon addition image in 19%, i.e. 74.7% of non-ruptured cuffs. Minimal loss of integrity was noted in 9.5% and was marked in 15.7%, i.e. 25.2% iterative tears.ANATOMOCLINICAL CORRELATIONS: The Constant score was strongly correlated with rotator cuff integrity (p<0001). This correlation was also found for force (p<0001), motion (0.01) and activity (0.04), but not for pain. The clinical outcome was correlated with extension, retraction, intrasubstance tear, and fatty degeneration of the lesion preoperatively. Anatomic results were statistically less favorable for tears which were older, extensive, retracted or associated with fatty degeneration. Age was correlated with extent of the initial tear and also with less favorable anatomic and clinical outcome. Occupational accidents were correlated with less favorable clinical outcome. CONCLUSION: Functional improvement after healing is a strong argument for repair. Arthroscopy has the advantage of combining a low complication rate with good clinical and anatomic results. Age is correlated with functional outcome and healing, but is not a contraindication.

[Proton therapy of occult neovessels in age-related macular degeneration]. / Protonthérapie des néovaisseaux occultes dans la dégénérescence maculaire liée à l'âge.

INTRODUCTION: The interest of radiation therapy in the management of age-related macular degeneration inaccessible to photocoagulation is still controversial. Our purpose was to demonstrate the feasibility and the possible efficacy of a single dose delivered to the macular region using a 65-MeV proton beam. MATERIAL AND METHODS: A phase II trial was set up using the cyclotron in Nice, France. Fifty-eight patients were included after signing an informed consent. All patients presented with occult subfoveal choroidal neovascularization. A single dose of 9.1 Gy (i.e., 10 Gy cobalt equivalent) was delivered to the macular region. RESULTS: The results were analyzed 3, 6, 12 and, 18 months after proton therapy. At 3 months, the visual acuity was stable or enhanced for 86% of patients, at 6 months for 82.3%, at 12 months for 80%, and at 18 months for 61%. For 22 patients at follow-up at 18 months, the reasons for a decrease in visual acuity were a macular hemorrhage for 4 patients and a progression of the neovascular membrane for 3 patients. No secondary effects related to the treatment have been observed. Regarding the lesions visible on the angiographies (i.e., hemorrhage, exudates, subretinal detachment), we observed a stabilization or a decrease in two-thirds of the cases. CONCLUSION: Preliminary results of single-dose proton therapy are at least comparable to those obtained by other teams. A second study is in progress comparing 3 dose levels, looking for a dose-effect relationship. Furthermore, a randomized study comparing a single proton dose to a placebo will be necessary to assess the long-term value of proton treatment.

Results of proton therapy of uveal melanomas treated in Nice.

PURPOSE: To present the first results of uveal melanomas treated with the Medicyc Cyclotron 65 MeV proton beam facility in Nice, analyzing the factors that affect the cause-specific survival (CSS), metastatic rate, and reporting the visual outcome. METHODS AND MATERIALS: This study concerns 538 patients referred by French institutions between June 1991 and December 1996. The eye and tumor parameters were measured using ultrasonography and angiography. Since 1994, CT scans were performed in most patients to help determine the axial length and the shape of the ocular globe. Tantalum clips were inserted around the tumor by the referring ophthalmologist. There were 349 posterior pole tumors (64.9%), 130 equatorial tumors (24.1%), and 59 ciliary body tumors (11%). Two hundred four patients (37.9%) had T1 or T2 tumors, and 334 patients (62.1%) had T3 or T4 tumors. The median tumor diameter was 14.6 mm, and the median tumor height was 5.1 mm. All patients received 52 Gy (57.20 Gy Co-equivalent dose) on 4 consecutive days. The data were analyzed by December 1997. RESULTS: The CSS was 77.4% at 78 months, the overall survival was 73.8% and the local control was 89.0%. The CSS was not influenced by the patient age or the site of the tumor. It was 81.5% for T1 and T2 tumors, versus 75% for T3 and T4 tumors (P = 0.035). It was found that the tumor diameter, rather than the height, was the most important parameter affecting outcome. The metastatic rate was 8%. It depended on the T stage, tumor diameter and thickness, but not the tumor site. Thirty-eight enucleations were performed, most of them due to tumor progression and/or glaucoma. One-third of the patients in whom visual acuity was adequately scored before and after treatment had a stable, if not improved vision, and half the patients retained useful vision after treatment. CONCLUSION: The outcome of patients suffering from uveal melanoma and treated with high-energy protons compares favorably with other techniques of treatment. The tumor dimensions affected CSS and metastatic rate. Even though two-thirds of patients had posterior pole tumors, half of them retained useful vision.

Boron neutron capture enhancement (BNCE) of fast neutron irradiation for glioblastoma: increase of thermal neutron flux with heavy material collimation, a theoretical evaluation.

Despite the fact that fast neutron irradiation of glioblastoma has shown on autopsies an ability to sterilize tumors, no therapeutic windows have been found for these particles due to their toxicity toward normal brain. Therefore, the Boron Neutron Capture Enhancement (BNCE) of fast neutron beam has been suggested. This paper addresses the problem of fast neutron beam collimation, which induces a dramatic decrease of the thermal neutron flux in the depth of the tissues when smaller irradiation fields are used. Thermoluminescent dosimeter TLD-600 and TLD-700 were used to determine the thermal neutron flux within a Plexiglas phantom irradiated under the Nice Biomedical Cyclotron p(60)+Be(32) fast neutron beam. A BNCE of 4.6% in physical dose was determined for a 10 x 10 cm2 field, and of 10.4% for a 20 x 20 cm2 one. A Dose Modification Factor of 1.19 was calculated for CAL 58 glioblastoma cells irradiated thanks to the larger field. In order to increase the thermal flux in depth while shaping the beam, heavy material collimation was studied with Monte Carlo simulations using coupled FLUKA and MCNP-4A codes. The use of 20 cm width lead blocks allowed a 2 fold thermal neutron flux increase in the depth of the phantom, while shielding the fast neutron beam with a fast neutron dose transmission of 23%. Using the DMF of 1.19, a BNCE of 40% was calculated in the beam axis. This enhancement might be sufficient to open, at least theoretically, a therapeutic window.

Combined use of FLUKA and MCNP-4A for the Monte Carlo simulation of the dosimetry of 10B neutron capture enhancement of fast neutron irradiations.

Boron neutron capture enhancement (BNCE) of the fast neutron irradiations use thermal neutrons produced in depth of the tissues to generate neutron capture reactions on 10B within tumor cells. The dose enhancement is correlated to the 10B concentration and to thermal neutron flux measured in the depth of the tissues, and in this paper we demonstrate the feasibility of Monte Carlo simulation to study the dosimetry of BNCE. The charged particle FLUKA code has been used to calculate the primary neutron yield from the beryllium target, while MCNP-4A has been used for the transport of these neutrons in the geometry of the Biomedical Cyclotron of Nice. The fast neutron spectrum and dose deposition, the thermal flux and thermal neutron spectrum in depth of a Plexiglas phantom has been calculated. The thermal neutron flux has been compared with experimental results determined with calibrated thermoluminescent dosimeters (TLD-600 and TLD-700, respectively, doped with 6Li or 7Li). The theoretical results were in good agreement with the experimental results: the thermal neutron flux was calculated at 10.3 X 10(6) n/cm2 s1 and measured at 9.42 X 10(6) n/cm2 s1 at 4 cm depth of the phantom and with a 10 cm X 10 cm irradiation field. For fast neutron dose deposition the calculated and experimental curves have the same slope but different shape: only the experimental curve shows a maximum at 2.27 cm depth corresponding to the build-up. The difference is due to the Monte Carlo simulation which does not follow the secondary particles. Finally, a dose enhancement of, respectively, 4.6% and 10.4% are found for 10 cm X 10 cm or 20 cm X 20 cm fields, provided that 100 micrograms/g of 10B is loaded in the tissues. It is anticipated that this calculation method may be used to improve BNCE of fast neutron irradiations through collimation modifications.

Proton beam dosimetry: a comparison between the Faraday cup and an ionization chamber.

From the theoretical point of view, the Faraday cup (FC) is an absolute instrument for fluence measurements of proton beams. As the FC is easily manufactured it can be considered an 'in-house' calibration system. Moreover, at the moment no national standards for proton dosimetry are available. Up to now the experimental tests of these instruments show that much study still has to be done to better understand their use in reference dosimetry. To investigate the possibility of using an FC as a secondary standard, an FC was jointly designed by the 'TERA Collaboration' and 'Centre Antoine-Lacassagne' (Nice, France) to evaluate the main parameters of the instrument. A comparison between two FCs of different designs--the 'TERA FC' and the 'Nice FC'--and an ionization chamber (IC) used for routine proton dosimetry was carried out. Results show that the two FCs agree to within 1.5-3.6%. While the differences between FC and IC are larger--6% for the 'TERA FC' and 8.2% for the 'Nice FC', the FC giving a lower dose evaluation--they follow the same trend shown by the calorimetric measurements. The data show that once the beam characteristics are defined, the fluence measurements are reproducible and show a good accuracy.

Changes in biological effectiveness with depth of the Medicyc neutron therapy beam.

V79 cells were exposed to fast neutrons generated by 60 MeV p-->Be produced by the cyclotron Medicyc at four different depths: 1.3, 25.8, 72.2 and 116.8 mm. Survival was assessed by the in vitro colony method. Mean inactivation doses (MID) were significantly different among the four points. The ratio of MID was used to determine the relative efficiency of the neutron beam at these points. Compared to 25.8 mm depth, a 40% increase in biological effect was observed at the superficial point versus a 14 to 16% decrease in effect for the deeper points. This is ascribed to absorption of low energy neutrons near the surface and to beam hardening with depth. Taking in consideration the relative physical dose delivered, these findings suggest that skin-sparing may be markedly reduced and that the lower effectiveness with depth should be kept in mind when dealing with deep tumours.

RBE variation between fast neutron beams as a function of energy. Intercomparison involving 7 neutrontherapy facilities.

In fast neutron therapy, the relative biological effectiveness (RBE) of a given beam varies to a large extent with the neutron energy spectrum. This spectrum depends primarily on the energy of the incident particles and on the nuclear reaction used for neutron production. However, it also depends on other factors which are specific to the local facility, eg, target, collimation system, etc. Therefore direct radiobiological intercomparisons are justified. The present paper reports the results of an intercomparison performed at seven neutrontherapy centres: Orléans, France (p(34)+Be), Riyadh, Saudi Arabia (p(26)+Be), Ghent, Belgium (d(14.5)+Be), Faure, South Africa (p(66)+Be), Detroit, USA (d(48)+Be), Nice, France (p(65)+Be) and Louvain-la-Neuve, Belgium (p(65)+Be). The selected radiobiological system was intestinal crypt regeneration in mice after single fraction irradiation. The observed RBE values (ref cobalt-60 gamma-rays) were 1.79 +/- 0.10, 1.84 +/- 0.07, 2.24 +/- 0.11, 1.55 +/- 0.04, 1.51 +/- 0.03, 1.50 +/- 0.04 and 1.52 +/- 0.04, respectively. When machine availability permitted, additional factors were studied: two vs one fraction (Ghent, Louvain-la-Neuve), dose rate (Detroit), influence of depth in phantom (Faure, Detroit, Nice, Louvain-la-Neuve). In addition, at Orléans and Ghent, RBEs were also determined for LD50 at 6 days after selective abdominal irradiation and were found to be equal to the RBEs for crypt regeneration. The radiobiological intercomparisons were always combined with direct dosimetric intercomparisons and, when possible in some centres, with microdosimetric investigations.

The Nice high-energy neutron facility: dosimetry intercomparisons.

Neutron dosimetry intercomparison studies have been undertaken at the Nice neutrontherapy facility with the staff at Louvain-la-Neuve which has had wide experience in both dosimetric and radiobiological intercomparisons. Tissue equivalent (TE) ionization chambers were first calibrated in 60Co beams and then exposed in the neutron beam at different depths in a water phantom; the largest difference observed in neutron beam measurements with all the chambers tested was 0.89%, and most of them agreed to within less than 0.5%. The gamma component at four depths was derived from measurements with Geiger-Müller counters; the results obtained with the two counters (Nice and Louvain-la-Neuve), expressed as a percentage of the total dose (neutron + gamma), agreed to within less than 0.03% and the value increased from 1.4 to 4.2% between 2 and 20 cm in depth.

Boron neutron capture irradiation: setting up a clinical programme in Nice.

Neutron capture irradiation aims to selectively destroy tumor cells using 10B(n,alpha)7Li nuclear reactions produced within themselves. Following the capture reaction, an alpha particle and a, 7Li ion are emitted. Carrying an energy of 2.79 MeV, they destroy all molecular structures along their path close to 10 microns. These captures, used exclusively with a 'slow' neutron irradiation, provide a neutron capture therapy (BNCT). If they are used in addition to a fast neutron beam irradiation, they provide a neutron capture potentiation (NCP). The Centre Antoine-Lacassagne in Nice is actively involved in the European Demonstration Project for BNCT of grade IV glioblastomas (GBM) after surgical excision and BSH administration. Taking into account the preliminary results obtained in Japan, work on an 'epithermal' neutron target compatible with various cyclotron beams is in progress to facilitate further developments of this technique. For NCP, thermalized neutron yield has been measured in phantoms irradiated in the fast neutron beam of the biomedical cyclotron in Nice. A thermal peak appears after 5 cm depth in the tissues, delayed after the fast neutron peak at 1.8 cm depth. Thus, a physical overdosage of 10% may be obtained if 100 ppm of 10B are assumed in the tissues. Our results using CAL 58 GBM cell line demonstrate a dose modification factor (DMF) of 1.19 when 100 ppm of boric acid are added to the growth medium. Thus for the particles, issued from neutron capture, a biological efficiency at least twice that of fast neutrons can be derived. These results, compared with historical data on fast neutron irradiation of glioblastoma, suggest that a therapeutic window may be obtained for GBM.

Proton therapy in ophthalmology: status report and problems encountered.

The proton therapy facility of the Centre Antoine-Lacassagne in Nice began treatment of ocular tumors in June 1991. Up to October 1995, a total number of 600 patients were treated. An overview of the cases treated during the first 4 years of activity is given and the main problems encountered in the field, possibly interacting with the accuracy and reliability of the dose distribution, are listed.

The RBE of fast neutrons for in vitro inactivation of human tumour cells determined by the ratio of mean inactivation doses.

In an effort to clarify the relationship between sensitivity of human tumour cells to low-LET and to fast neutron irradiation, 10 human tumour cell lines were exposed to cobalt gamma-rays and to 60 MeV (p -> Be+) neutron beam. The data were pooled with results of 31 human tumour cell lines previously published. The analysis of date using the linear-quadratic model indicated that not only alpha values increased after neutron irradiation, but so did beta values too, although to a lesser extent. The mean inactivation dose (MID) was derived for each cell line from the linear-quadratic parameters after low-LET and high-LET exposure. MID values following neutron irradiation were closely correlated to those after gamma-ray irradiation. In these 41 cell lines, the extreme values of RBE derived by the ratio of MID varied by a factor of 3 among the cell lines. RBE was positively correlated to photon MID, meaning that intrinsically radiation resistant tumour cells have a higher neutron RBE, on average. Similar findings were observed if alpha ratios were used instead of MID ratios. In addition, the RBE/dose variations were more marked in cells with the higher RBE. Taken together, these data suggest that, although considerable variations exist among human tumour cell lines, intrinsically radioresistant cells are relatively more sensitized when exposed to high LET beams than radioresponsive tumours. An 'intrinsic gain factor' may thus be expected in irradiating radiation resistant tumours with fast neutrons, in addition to the hypoxic or kinetic gain factors. Because the quadratic component is still present after neutron irradiation, we suggest using MID ratio as a reference RBE when comparing survival curves of cells exposed to radiations of different qualities.