Centre Antoine-Lacassagne Research Articles

A 60 MeV proton beam-line dedicated to research and development programs

A new proton beam-line dedicated to R&D programs has been developed at CentreAntoine Lacassagne (CAL), in Nice (France), in collaboration with the Centrenational d'études spatiales (CNES). This is the second beam-line of the MEDICYC 65 MeV cyclotron that is currently in operation, the first being the clinical ‘eye-line’ used for ocular proton therapy. The R&D beam-line is proposed with two configurations, the first producing a Gaussian narrow beam of a few mm width, the second a 100 mm diameter flat beam with a homogeneity better than ±3%. The energy range is (20 - ∼60) MeV, where the exact upper limit depends on the beam configuration being used. The energy spread of the non-degraded beam is (0.3 ± 0.1) MeV. A beam current between 10 pA and 10 μA can be produced with a stability better than 0.2% above 100 pA, and 2% below. The beam can be monitored online at a precision better than 5% in the flux range 1E5 (1E6) – 1E9 (1E10) p/cm2/s for a flat (Gaussian) configuration, although work is in progress to extend this range. Targeted applications for the R&D beam-line are instrumentation research, radiation tolerance tests of components and radiobiology.

The development of a treatment control system for a passive scattering proton therapy installation

Ocular melanoma has been treated using proton therapy at the Centre Antoine Lacassagne (CAL) since 1991, following the commissioning of the 65 MeV cyclotron MEDICYC and its associated beam-lines a few years earlier. The dedicated eye-line is optimized for shallow tumors and sharp penumbrae and provides state-of-the-art quality of care. The cyclotron, beam-lines and treatment systems, which are maintained exclusively by the staff at CAL, have proven to be exceptionally robust with up-times consistently above 95%. The systems are however aging and need to be replaced to ensure a continuation of ocular treatments with MEDICYC. This paper describes the development and performance of a new treatment control and dose measurement system for MEDICYC. Software and hardware architectural design choices are discussed in context of the requirements for dose delivery precision, robustness and patient safety. The performance of the treatment delivery, dose monitoring and beam quality assurance systems are presented.

Study of the responses and calibration procedures of neutron and gamma area and environmental detectors for use in proton therapy

Ambient dose equivalent measurements with radiation protection instruments are associated to large uncertainties, mostly due to the energy dependence of the instrument response and to the dissimilarity between the spectra of the standard calibration source and the workplace field. The purpose of this work is to evaluate its impact on the performance of area and environmental detectors in the proton therapy environment, and to provide practical solutions whenever needed and possible. The study was carried out at the Centre Antoine Lacassagne (CAL) proton therapy site, and included a number of commercially available area detectors and a home-made environmental thermoluminescent dosimeter based on a polyethylene moderator loaded with TLD600H/TLD700H pairs. Monte Carlo simulations were performed with MCNP to calculate, first, missing or partially lacking instrument responses, covering the range of energies involved in proton therapy. Second, neutron and gamma spectra were computed at selected positions in and outside the CAL proton therapy bunkers. Appropriate correction factors were then derived for each detector, workplace location and calibration radionuclide source, which amounts to up to 1.9 and 1.5 for neutron and photon area detectors, respectively, and suggest that common ambient dose equivalent instruments might not meet IEC requirements. The TLD environmental system was calibrated in situ and appropriate correction factors were applied to account for the cosmic spectra. Measurements performed with this system from 2014 to 2017 around the installation were consistent with reference natural background dose data and with pre-operational levels registered at the site before the construction of the building in 1988, showing thus no contribution from the site clinical activities. An in situ verification procedure for the radiation protection instruments was also implemented in 2016 at the low energy treatment room using the QA beam reference conditions. The method presents main methodological, practical and economic advantages over external verifications.

548P - Can we improve cost effectiveness of oncology clinical trials workflow? A prospective RECIST 1.1 study

Background: Oncology clinical trials require reliable imaging data management, however recurring nonconformity issues are commonly reported. Radiological workload is increasing, which reduces radiologist’s availability and potentially affects diagnostics quality. In this study, we compared performances of an institutional standard radiological workflow (SW) and a novel “hybrid workflow” (HW). Methods: We prospectively studied imaging data of 40 patients included in a RECIST 1.1 clinical trial (Apr-Dec, 2017) at Centre Antoine Lacassagne (CAL), Nice, France. 97 time-points were reviewed by 7 radiologists and one trained technologist. Nonconformities using the SW were retrieved from CALs’ 2015 archives. SW involved radiologists who used the Advantage Workstation platform without electronic reporting system (General Electric, USA). For the HW, radiologists performed all baseline evaluations and the technologist did the subsequent generic measures on follow ups. Radiologists then checked the technologist’s findings, before confirming the evaluations. The HW used LMS (Median Technologies, France) featuring an electronic reporting system. An independent body compared SW and HW reading time and nonconformity occurrences. Results: Using SW, 19 types of nonconformities were found: blank report (13%); unsigned report (11%); undocumented change of tumor burden (10%); undocumented new lesions (9%); missing/wrong patients’ visit date (7%); undocumented tumors location (5%); error in tumor burden change (5%). SW and HW nonconformities affected 55% (179/323) and 5% (2/40) of reports respectively (p < 0.001). HW nonconformities were: one wrong login name entered in the LMS platform and one erroneous time point numbering. SW required, on average, 11’30” [10’06”; 13’20”] to perform the radiological analysis per timepoint. HW required 1’35” [40”; 5’08”] for radiologists, and 12’18” [11’12”; 14’18”] for the technologist. Conclusions: HW significantly reduced the number of trial nonconformities and saved 87% of radiologists’ time while keeping their expertise in the final decisions. HW could represent an efficient cost reduction opportunity associated with imaging trial quality improvements. Legal entity responsible for the study: Antoine Lacassagne Anticancer Center. Funding: Has not received any funding. Disclosure: H. Beaumont, C. Klifa: Employee: Median Technologies. All other authors have declared no conflicts of interest.

Dose calculation accuracy at presence of dental implants on UNCORRECTED and metal artifact reduced computed tomography data

Dose calculation accuracy at presence of dental implants on UNCORRECTED and metal artifact reduced computed tomography data

Study of the secondary neutral radiation in proton therapy: Toward an indirect in vivo dosimetry

Secondary particles produced in the collision of protons with beam modifiers are of concern in proton therapy. Nevertheless, secondary radiation can provide information on the dosimetric parameters through its dependency on the modulating accessories (range shifter and range modulating wheel). Relatively little data have been reported in the literature for low-energy proton beams. The present study aims at characterizing the neutron and photon secondary radiation at the low-energy proton therapy facility of the Centre Antoine Lacassagne (CAL), and studying their correlation to the dosimetric parameters to explore possible practical uses of secondary radiation in the treatment quality for proton therapy. The Monte Carlo code MCNPX was used to simulate the proton therapy facility at CAL. Neutron and photon fluence, Φ, and ambient dose equivalent per proton dose, H∗(10)∕D, were determined across the horizontal main plane spanning the whole treatment room. H∗(10)∕D was also calculated at two positions of the treatment room where dosimetric measurements were performed for validation of the Monte Carlo calculations. Calculations and measurements were extended to 100 clinical spread-out Bragg Peaks (SOBPs) covering the whole range of therapeutic dose rates (D∕MU) employed at CAL. In addition, the values of D and MU were also calculated for each SOBP and the results analyzed to study the relationship between secondary radiation and dosimetric parameters. The largest production of the secondary particles takes place at the modulating devices and the brass collimators located along the optical bench. Along the beam line and off the beam axis to 2.5 m away, H∗(10)∕D values ranged from 5.4 μSv∕Gy to 5.3 mSv∕Gy for neutrons, and were 1 order of magnitude lower for photons. H∗(10)∕D varied greatly with the distance and angle to the beam axis. A variation of a factor of 5 was found for the different range of modulations (SOBPs). The ratios between calculations and measurements were 2.3 and 0.5 for neutrons and photons, respectively, and remained constant for all the range of SOBPs studied, which provided validation for the Monte Carlo calculations. H∗(10)∕D values were found to correlate to the proton dose rate D∕MU with a power fit, both for neutrons and photons. This result was exploited to implement a system to obtain D∕MU values from the measurement of the integrated photon ambient dose equivalent H∗(10) during treatment, which provides a method to control the dosimetric parameters D∕MU and D. The treatment room at CAL is moderately polluted by secondary particles. The constant ratio between measurements and calculations for all SOBPs showed that simulations correctly predict the dosimetric parameters and the dependence of the production of secondary particles on the modulation. The correlation between H∗(10)∕D and D∕MU is a useful tool for quality control and is currently used at CAL. This system works as an indirect in vivo dosimetry method, which is so far not feasible in proton therapy. This tool requires very simple instrumentation and can be implemented from the measurement of either photons or neutrons.

Développement de l’appareil Papillon 50™ et de ses applicateurs pour la radiothérapie 50 kV des cancers du rectum et de la peau

ObjectiveContact X-Ray 50kV (CXRT) has proven its efficiency to treat rectum and skin cancers. The goal of this technological research was to design and produce a new CXRT machine with dedicated applicators to replace the Philips unit not any more manufactured. Materials and methodsThe P50 was assembled in UK and the characteristics of the machine were evaluated with spectrometers, ions chambers, Gafchromic films and Monte Carlo code. The applicators were designed and manufactured in Nice. Dosimetric data were measured for each applicator. Validated protocols were used to treat patients. ResultsBetween September 2009 and November 2011, the performances of the P50 was judged satisfactory with a dose rate close to 15Gy/min depending on the applicator. The dose distribution was according to objectives. Clinical results achieved in 62 patients treated in centre Antoine-Lacassagne for rectum, skin or eyelid cancers confirmed the efficiency and good tolerance of CXRT. Similar results in rectal cancer were observed in Clatterbridge with 120 rectal cancers treated with P50. DiscussionThese results are encouraging and should contribute to the international dissemination of CXRT. New machine (Papillon Plus) should be designed and produced for intraoperative irradiation and treatment of vaginal vault. ConclusionThis experience of research and development well structured within the frame of TecSan project should be encouraged further to facilitate technological innovation in the field of radiotherapy.

Contact radiotherapy using a 50 kV X-ray system: Evaluation of relative dose distribution with the Monte Carlo code PENELOPE and comparison with measurements

This paper presents a dosimetric study concerning the system named “Papillon 50” used in the department of radiotherapy of the Centre Antoine-Lacassagne, Nice, France. The machine provides a 50kVp X-ray beam, currently used to treat rectal cancers. The system can be mounted with various applicators of different diameters or shapes. These applicators can be fixed over the main rod tube of the unit in order to deliver the prescribed absorbed dose into the tumor with an optimal distribution. We have analyzed depth dose curves and dose profiles for the naked tube and for a set of three applicators. Dose measurements were made with an ionization chamber (PTW type 23342) and Gafchromic films (EBT2). We have also compared the measurements with simulations performed using the Monte Carlo code PENELOPE. Simulations were performed with a detailed geometrical description of the experimental setup and with enough statistics. Results of simulations are made in accordance with experimental measurements and provide an accurate evaluation of the dose delivered. The depths of the 50% isodose in water for the various applicators are 4.0, 6.0, 6.6 and 7.1mm. The Monte Carlo PENELOPE simulations are in accordance with the measurements for a 50kV X-ray system. Simulations are able to confirm the measurements provided by Gafchromic films or ionization chambers. Results also demonstrate that Monte Carlo simulations could be helpful to validate the future applicators designed for other localizations such as breast or skin cancers. Furthermore, Monte Carlo simulations could be a reliable alternative for a rapid evaluation of the dose delivered by such a system that uses multiple designs of applicators.

Aromatase inhibition in male breast cancer patients: biological and clinical implications

BackgroundThe role of aromatase inhibitors (AIs) and their impact on estradiol (E2) levels remain unknown in male breast cancer (MBC) patients. Patients and methodsMBC patients with metastatic disease and those treated with AIs were selected from the breast cancer database of the Centre Antoine-Lacassagne (Nice, France). Sex hormone levels were retrospectively assessed on serum samples from our institutional serum bank. ResultsFifteen patients entered the study. Two patients (13%) had complete response, four patients (27%) had partial response, two patients (13%) had stable disease and seven patients (47%) had progressive disease. The median progression-free survival and overall survival were 4.4 months [95% confidence interval (CI) 0.1–8.6] and 33 months (95% CI 18.4–47.6), respectively. All assessable patients (n = 6) had E2 levels less than the lower limit of the assay during AI treatment. Among them, three had partial response, one had stable disease and two had progressive disease. A large increase in follicle-stimulating hormone, luteinizing hormone and E2 levels was observed in one responding patient at progression. ConclusionsAIs are active in MBC patients. This activity is correlated with a significant reduction in E2 levels. Secondary resistance is in part related to a deleterious feedback loop resulting in a significant increase in substrate for aromatization.

Aromatase inhibition in male breast cancer patients: Biological and clinical implications

1130 Background: Because male breast cancer (MBC) is rare, treatment recommendations are derived from results of trials in female patients (pts). Although, several studies have shown the superiority of third-generation aromatase inhibitors (AI) over tamoxifen in menopausal women with advanced breast cancer, the role of such molecules remains unknown in male pts. We report here the largest experience about the efficacy of AI in MBC pts with advanced disease and their impact on estradiol (E) levels. Methods: MBC pts were selected from the breast cancer database of the Centre Antoine-Lacassagne (Nice, France) as follows: Metastatic disease with at least one measurable or assessable non-measurable lesion, estrogen receptor (ER) and/or or progesterone receptor (PR) positive, availability of complete clinical and histological data, evidence of progressive disease at initiation of AI, receipt of at least one month of treatment with non steroidal (anastrozole, letrozole) or steroidal (exemestane) AI. Sex hormone levels were retrospectively assessed on serum samples from our institutional serum bank. Results: 15 pts entered the study. Median age was 68 (range 39–85). 7 pts received previous lines of hormonal therapy (median = 1) and 3 pts a previous line of chemotherapy before the introduction of AI. The best response was complete response in 2 pts (13%), partial response in 4 pts (27%), stable disease (SD) in 2 pts (13%) and progressive disease (PD) in 7 pts (47%). The median duration of objective response (OR) was 11.6 months (95% confidence interval [CI] 7.6–15.5). At the time of analysis, 8 pts (53%) had died and 7 (47%) were still alive. The median PFS and OS were 4.4 months (95% CI 0.1–8.6) and 33 months (95% CI 18.4–47.6) respectively. The 1-year PFS and OS rates were 20% (95% CI 9.7–30.3) and 84.6% (95% CI 74.6–94.6), respectively. 9 out of 11 pts with available samples had E levels less than the lower limit of the assay during AI treatment. Among the 9 pts with E level decrease, four had OR, one had SD, and four had PD. 1 pt had E levels higher than the upper limit of the assay during AI treatment. This pt showed disease progression. Further data on FSH and testosterone levels will be presented at the meeting. Conclusions: AI are active in MBC pts. This activity is correlated with a significant reduction in E levels. No significant financial relationships to disclose.

Management of oral and gastrointestinal mucositis: ESMO Clinical Recommendations

Management of oral and gastrointestinal mucositis: ESMO Clinical Recommendations D. E. Peterson, R.-J. Bensadoun & F. Roila On behalf of the ESMO Guidelines Working Group* Department of Oral Health and Diagnostic Sciences, School of Dental Medicine, Head and Neck/Oral Oncology Program, Neag Comprehensive Cancer Center, Farmington, USA; Department of Radiation Oncology, Centre Antoine-Lacassagne, France; Department of Medical Oncology, S. Maria Hospital, Terni, Italy

Free‐Flap Head and Neck Reconstruction and Quality of Life: A 2‐Year Prospective Study

This prospective study was designed to evaluate quality of life (QOL) after free-flap head and neck reconstruction. Prospective study. : Between January 2004 and December 2005, a total of 95 patients underwent microvascular reconstruction of the head and neck at our Institution (Centre Antoine-Lacassagne, Nice, France) and were initially included in this study. The European Organization for Research and Treatment of Cancer (EORTC) Core Quality of Life Questionnaire and the EORTC Head and Neck Cancer Quality of Life Questionnaire were completed before surgery, and at 6 and 12 months thereafter. Sixty-five patients completed the questionnaires on at least two of the assessment dates. Predictive factors of Quality of Life (QOL) scores at 6 months were researched among the following: age, sex, comorbidity, radiotherapy, tumor recurrence, tumor stage, and type of surgery. Global QOL remained stable over time. Physical, social, and role functioning deteriorated significantly after treatment. Pain decreased markedly. Social eating, senses, and speech difficulties increased significantly at 6 months, but stabilized between 6 and 12 months. Problems concerning mouth opening and social contact augmented progressively until the 12th postoperative month. Sex, type of surgery, and radiotherapy were the main factors influencing QOL 6 months after treatment. Despite some functional impairments, global QOL was preserved after major head and neck ablative surgery and microvascular free-flap reconstruction.

Management of oral and gastrointestinal mucositis: ESMO Clinical Recommendations

Management of oral and gastrointestinal mucositis: ESMO Clinical Recommendations D. E. Peterson, R.-J. Bensadoun & F. Roila On behalf of the ESMO Guidelines Working Group* Department of Oral Health and Diagnostic Sciences, School of Dental Medicine, Head and Neck/Oral Oncology Program, Neag Comprehensive Cancer Center, Farmington, USA; Department of Radiation Oncology, Centre Antoine-Lacassagne, France; Department of Medical Oncology, S. Maria Hospital, Terni, Italy

Contact X-ray Therapy for Rectal Cancer: Experience in Centre Antoine-Lacassagne, Nice, 2002–2006

To report the results of using contact X-ray (CXR), which has been used in the Centre-Lacassagne since 2002 for rectal cancer. A total of 44 patients were treated between 2002 and 2006 using four distinct clinical approaches. Patients with Stage T1N0 tumors were treated with transanal local excision (TLE) and adjuvant CXR (45 Gy in three fractions) (n = 7). The 11 inoperable (or who had refused surgery) patients with Stage T2-T3 disease were treated with CXR plus external beam radiotherapy (EBRT). Those with Stage T3N0-N2 tumors were treated with preoperative CXR plus EBRT (with or without concurrent chemotherapy) followed by surgery (n = 21). Finally, the patients with Stage T2 disease were treated with CXR plus EBRT followed by TLE (n = 5). The median follow-up was 25 months. In the 7 patients who underwent TLE first, no local failure was observed, and their anorectal function was good. Of the 11 inoperable patients who underwent CXR plus EBRT alone, 10 achieved local control. In the third group (preoperative CXR plus EBRT), anterior resection was performed in 16 of 21 patients. Complete sterilization of the operative specimen was seen in 4 cases (19%). No local recurrence occurred. Finally, of the 5 patients treated with CXR plus EBRT followed by TLE, a complete or near complete clinical response was observed in all. TLE with a R0 resection margin was performed in all cases. The rectum was preserved with good function in all 5 patients. These early results have confirmed that CXR combined with surgery (or alone with EBRT) can play a major role in the conservative and curative treatment of rectal cancer.

Comparison of 50 kV Facilities for Contact Radiotherapy

The radiation characteristics of a short source to surface distance (SSD) contact therapy tube in clinical use at the Centre Antoine-Lacassagne, Nice and a long SSD unit at the Clatterbridge Centre for Oncology were compared. The output from the tube at Nice had a dose rate of approximately double that of the tube at Clatterbridge, whereas the tube at Clatterbridge had a slightly higher value of the half value layer. Depth dose measurements were made with GafChromic MD55 film and SSD corrected depth dose curves showed good agreement between centres. Profiles at 2mm depth also showed comparable levels of flatness and uniformity.

Parotid gland sparing with step-and-shoot intensity modulated radiation in nasopharyngeal and oropharyngeal tumors. 3 years experience at the centre antoine-lacassagne

Parotid gland sparing with step-and-shoot intensity modulated radiation in nasopharyngeal and oropharyngeal tumors. 3 years experience at the centre antoine-lacassagne

Monte Carlo simulation of a protontherapy platform devoted to ocular melanoma

Patients with ocular melanoma have been treated since June 1991 at the medical cyclotron of the Centre Antoine Lacassagne (CAL). Positions and sizes of the ocular nozzle elements were initially defined based on experimental work, taking as a pattern functional existing facilities. Nowadays Monte Carlo (MC) calculation offers a tool to refine this geometry by adjusting size and place of beam modeling devices. Moreover, the MC tool is a useful way to calculate the dose and to evaluate the impact of secondary particles in the field of radiotherapy or radiation protection. Both LINAC and cyclotron producing x rays, electrons, protons, and neutrons are available in CAL, which suggests choosing MCNPX for its particle versatility. As a first step, the existing installation was input in MCNPX to check its aptitude to reproduce experimentally measured depth-dose profile, lateral profile, output-factor (OF), and absolute dose. The geometry was defined precisely and described from the last achromatic bending magnet of our proton beam line to the position of treated eyes. Relative comparisons of percentage depth-dose and lateral profiles, performed between measured data and simulations, show an agreement of the order of 2% in dose and 0.1 mm in range accuracy. These comparisons, carried out with and without beam-modifying device, yield results compatible to the required precision in ocular melanoma treatments, as long as adequate choices are made on MCNPX input decks for physics card. Absolute dose and OF issued from calculations and measurements were also compared. Results obtained for these two kinds of data, carried out in the simplified situation of an unmodulated beam, indicate that MC calculation could effectively complement measurements. These encouraging results are a large source of motivation to promote further studies, first in a new design of the ocular nozzle, and second in the analysis of the influence of beam-modifying devices attached to the final patient collimator, such as wedge or compensators, on dose values.

Radiotherapy in the conservative treatment of rectal cancer. Evidence-based medicine and opinion

Background and purpose This lecture is given on behalf of my former Lyon Sud Radiotherapy department (Dr P. Romestaing) and of the Radiotherapy Department of Centre Antoine-Lacassagne in Nice (Dr A. Courdi) without which it would have been impossible to produce any original clinical data. The major benefit from radiotherapy (RXT) in oncology can be summarized with 3 ‘C’: cure–cost effectiveness–conservative treatment. Patients and methods Rectal cancer illustrates the hypothesis that radiotherapy can increase the chance of conservative treatment (with sphincter preservation SP). Sphincter preservation is a complex process, and only randomized trials can be used to see if preoperative treatment can increase SP. Results Different phase III trials have shown that: preoperative RXT is superior to postop RX (local control—toxicity—SP), preoperative RXT with immediate surgery does not increases SP, preoperative RXT with delayed surgery increases SP, concurrent chemotherapy with RXT has not yet proven to increase SP, important dose escalation (90 Gy) with contact X-ray RXT increases complete clinical tumour response and SP. Conclusions The surgeon is the key person for the cure of rectal cancer and mainly responsible for the decision of sphincter preservation. The experience gained with contact X-ray therapy stresses the importance of a complete clinical tumor response before surgery to increase the chance of sphincter preservation. ‘High dose small volume’ RXT is a key factor to achieve such a complete clinical tumor response.

Reappraisal of the role of endobronchial brachytherapy in the management of lung cancer: ten years' experience at the centre Antoine-Lacassagne

Intra-operative intertitial brachytherapy has been applied in the curative and palliative treatment of lung cancer. Implantation of radio-active sources offers an advantage over external irradiation because of the limited penetrability from source to prescription point, resulting in rapid dose fall-off and sparing of surrounding normal tissues. The aim of this study was to re-evaluate retrospectively the Antoine-Lacassagne cancer center experience in endobronchial brachytherapy by low dose rate (LDR) or high dose rate (HDR) and to design perspectives for the next decades. Evaluation was based on analysis of toxicities, response rates and survival. From october 1989 to june 1999, 31 consecutive patients with bronchogenic carcinoma were treated. Thirteen and 18 patients received LDR and HDR, respectively. The mean age was 65 years (range 44 to 79 years). Inclusion criteria were, for palliative treatment, incurable endobronchial cancer, and for curative treatment, residual tumor in the margins after resection, or endobronchial tumor could not be treated surgically. Exclusion criteria were sites of lesion unsuitable for placement of the brachytherapy catheter. Evaluation of complications and clinical response were based on endoscopic evaluation one month after the last session and at less one year after the end of treatment. Eighty-seven courses have been performed: 65 by LDR and 22 by HDR. Thirty-six courses have been performed in the palliative group, 51 courses in the curative group. Seven patients among 31 presented acute complications and 18/31 late complications. Complete global response rate was 14/30 evaluable patients (47%). Mean overall global survival was 23 months with a median follow-up of 3.5 years. These results confirm the efficacy of endobronchial brachytherapy as well as palliative or curative treatment, but the improvement of results will essentially depend on our capacity to better define our indications and underlie the necessity to perform phase III international randomised trial.

801 Poster Parotid gland sparing with step-and-shoot intensity modulated radiation therapy (IMRT) in nasopharyngeal (NP) and oropharyngeal (OP) tumors. Preliminary clinical experience at the Centre Antoine-Lacassagne (CAL)

801 Poster Parotid gland sparing with step-and-shoot intensity modulated radiation therapy (IMRT) in nasopharyngeal (NP) and oropharyngeal (OP) tumors. Preliminary clinical experience at the Centre Antoine-Lacassagne (CAL)