Comparison between the HyperArc™ technique and the CyberKnife® technique for stereotactic treatment of brain metastases.

PURPOSE: The purpose of this study was to compare the planimetric capacities between HyperArc™-based stereotactic radiosurgery and robotic radiosurgery system-based planning using CyberKnife® M6 for single and multiple cranial metastases. MATERIALS AND METHODS: We evaluated 51 treatment plans for cranial metastases, including 30 patients with a single lesion and 21 patients with multiple lesions, treated with the CyberKnife® M6. These treatment plans were optimized using the HyperArc™ (HA) system with the TrueBeam. The comparison of the quality of the treatment plans between the two treatment techniques (CyberKnife and HyperArc) was performed using the Eclipse treatment planning system. Dosimetric parameters were compared for target volumes and organs at risk. RESULTS: Coverage of the target volumes was equivalent between the two techniques, whereas median Paddick conformity index and median gradient index for all target volumes were 0.9 and 3.4, respectively for HyperArc plans, and 0.8 and 4.5 for CyberKnife plans (P<0.001). The median dose of gross tumor volume (GTV) for HyperArc and CyberKnife plans were 28.4 and 28.8, respectively. Total brain V18Gy and V12Gy-GTVs were 11cm3 and 20.2cm3 for HyperArc plans versus 18cm3 and 34.1cm3 for CyberKnife plans (P<0.001). CONCLUSION: The HyperArc provided better brain sparing, with a significant reduction in V12Gy and V18Gy, associated with a lower gradient index, whereas the CyberKnife gave a higher median GTV dose. The HyperArc technique seems to be more appropriate for multiple cranial metastases and for large single metastatic lesions.

[Lung cancer and pulmonary metastasis treated by stereotactic radiosurgery: Evaluation of the relevance of realisation of 3 4D CT by the RPM technique]. / Cancers et métastases bronchiques traités par irradiation stéréotaxique pulmonaire : évaluation de la pertinence de réalisation de trois scanographies quadridimensionnelles par la technique RPM.

PURPOSE: Stereotactic lung radiosurgery has been carried out in the team at the Georges-François-Leclerc centre (CGFL) in Dijon since 2008 on a Truebeam® accelerator (Varian®) with the RPM technique. MATERIALS AND METHODS: Fifty patients with primary T1-T2 stage lung cancer (n=30) or lung metastasis (n=20) were included in the study. Since 2014, 3 successive 4D scanners on D1, D2 and D3, have been produced in order to ensure the reproducibility of ITV (Internet Target Volume). The 3 ITVs are contoured (ITV 1, 2 and 3) from the MIP (Maximum Intensity Projection) of each of the 3 scanners. A global ITV is created from the ITV volumes of the 3 scanners (MIP 2 and 3 merged with MIP 1). A CBCT (Cone Beam Computerised Tomography) is performed at the start of each irradiation session to position the patient. The study consisted in analysing the relevance of the realisation of 3 different scanners before dosimetry to define the ITV and in comparing the volumes contoured on the different CBCT to the ITV to make sure that the tumour volume is well included in the ITV during the sessions. RESULTS: There is a strong correlation between the different ITVs 1, 2, 3 and global, as well as between the volumes obtained on the different CBCTs. The correlation coefficient between the different ITVs and the volumes contoured on CBCT was high for upper lobar lesions. In terms of tolerance, the FEV1 (Maximum volume expired during the first second) did not seem to be a significant factor influencing the correlation between the ITV and the volumes bypassed on CBCT. CONCLUSION: Performing a single 4D planification CT is sufficient to consider stereotactic lung irradiation, regardless of the location of the lung lesions. The correlation coefficient between ITV and CBCT was high for upper lobar lesions.

[Can stereotactic body radiotherapy replace brachytherapy for locally advanced cervical cancer? French society for radiation oncology statement]. / La radiothérapie stéréotaxique peut-elle remplacer la curiethérapie pour les cancers du col utérin localement évolués ? Positionnement de la Société française de radiothérapie oncologique.

Brachytherapy is part of the treatment of locally advanced cervical cancers, accounting for about half of the total delivered dose. The benefit of dose escalation is the most important in advanced cases or if the tumor has responded poorly. The use of interstitial implantations makes it possible to reach doses of the order of 85 to 90Gy (including external beam radiotherapy contribution) in most patients, through image-guided approaches. Brachytherapy delivery is one of the quality criteria for patient care. To date, no data allow us to consider as an alternative the use of external boost through intensity-modulated or stereotactic body radiotherapy. Indeed, the doses delivered to the tumor and the capacity to spare normal tissues remains lower, as compared to what is permitted by brachytherapy. It is therefore appropriate for centers that do not have access to the technique to establish networks with centers where brachytherapy is performed, to allow each patient to have access to the technique. It is also necessary to promote brachytherapy teaching. The issue of reimbursement will be crucial in the coming years to maintain expertise that is today insufficiently valued in its financial aspects, but has a very high added value for patients.

High dose rate brachytherapy with customized applicators for malignant facial skin lesions.

PURPOSE: Brachytherapy is a well-known treatment in the management of skin tumors. For facial or scalp lesions, applicators have been developed to deliver non-invasive treatment. We present cases treated with customized applicators with high dose rate system. MATERIAL AND METHODS: Patients with poor performance status treated for malignant skin lesions of the scalp or the facial skin between 2011 and 2014 were studied. Afterloading devices were chosen between Freiburg(®) Flap, silicone-mold or wax applicators. The clinical target volume (CTV) was created by adding margins to lesions (10mm to 20mm). The dose schedules were 25Gy in five fractions for postoperative lesions, 30Gy in six fractions for exclusive treatments and a single session of 8Gy could be considered for palliative treatments. RESULTS: In 30 months, 11 patients received a treatment for a total of 12 lesions. The median age was 80 years. The median follow-up was 17 months and the 2-year local control rate was 91%. The mean CTV surface was 41.1cm(2) with a mean thickness of 6.1mm. We conceived three wax applicators, used our silicone-mold eight times and the Freiburg(®) Flap one time. We observed only low-grade radiodermitis (grade I: 50%, grade II: 33%), and no high-grade skin toxicity. CONCLUSION: High dose rate brachytherapy with customized applicators for facial skin and scalp lesions is efficient and safe. It is a good modality to treat complex lesions in patients unfit for invasive treatment.

[Equipment and positioning technologies in stereotactic body radiation therapy]. / Appareillage et technologies de repositionnement en radiothérapie stéréotaxique extracrânienne.

Strereotactic body radiation therapy needs adapted or dedicated equipment to allow fulfilling the particular conditions of the stereotactic treatments: submillimetric accuracy during the treatment delivery, high doses for a reduced number of sessions. This kind of treatment can be either performed using delivery equipment conceived and dedicated to the technique, or performed on conventional machines adapted to meet the criteria. Contrary to intracranial treatments, the positioning of the target volume raises new difficulties, mainly due to the diversity of localization to treat and also due to inter- and intrafraction movements that can occur. To reduce these effects that could affect the irradiation accuracy, positioning or movement compensation, mostly due to respiration, tools have been developed.

[Evaluation of transit in vivo dosimetry using portal imaging and comparison with measurements using diodes]. / Évaluation d'une dosimétrie in vivo de transit utilisant l'imageur portal et comparaison avec les mesures par diodes.

PURPOSE: In vivo dosimetry transit using portal imaging is a promising approach for quality assurance in radiotherapy. A comparative evaluation was conducted between a commercial solution, EPIgray(®) and an in vivo dosimetry control reference using semiconductors diodes. MATERIAL AND METHODS: The performance of the two in vivo dosimetry methods was assessed. The primary endpoint was the dose deviation between the reconstructed dose at the prescription point and the measured dose using the ionization chamber in phantoms or the calculated predictive dose by the treatment planning system with patients. The deviation threshold was set to ±5%. In total, 107 patients were prospectively included and treated with 3D-conformal radiotherapy (3D-CRT) or intensity-modulated radiotherapy (IMRT) techniques for tumours of the brain, chest and head and neck. RESULTS: The dosimetric accuracy of EPIgray(®) in phantom were comparable to diodes in terms of repeatability (0.11%), reproducibility (0.29-0.51%) with a mean dose deviation of 0.17% (SD: 1.11). The rates of radiotherapy sessions out of the tolerance for the brain (3D-CRT and IMRT), thorax (3D-CRT) and the head and neck (IMRT) were respectively 0%, 9.6% and 5.3% with a mean dose deviation ranging between 0.49% and 1.53%. The mean of dose deviation between three consecutive sessions with EPIgray(®) validates 99.1% of treatments. CONCLUSION: The performance of EPIgray(®) in in vivo dosimetry is consistent with the recommendations of the European Society for Radiotherapy and Oncology (ESTRO) and equivalent to semiconductor diodes for 3D-CRT. It also allows adequate control for IMRT, which is technically difficult to perform with the diodes.

[Development of external quality control protocol for CyberKnife beams dosimetry: preliminary tests multicentre]. / Développement d'une procédure de contrôle de qualité externe des faisceaux du CyberKnife: étude préliminaire multicentrique.

PURPOSE: To develop an external quality control procedure for CyberKnife(®) beams. This work conducted in Nancy, has included a test protocol initially drawn by the medical physicist of Nancy and Lille in collaboration with Equal-Estro Laboratory. MATERIALS AND METHODS: A head and neck anthropomorphic phantom and a water-equivalent homogeneous cubic plastic test-object, so-called "MiniCube", have been used. Powder and solid thermoluminescent dosimeters as well as radiochromic films have been used to perform absolute and relative dose studies, respectively. The comparison between doses calculated by Multiplan treatment planning system and measured doses have been studied in absolute dose. The dose distributions measured with films and treatment planning system calculations have been compared via the gamma function, configured with different tolerance criteria. RESULTS: This work allowed, via solid thermoluminescent dosimeter measurements, verifying the beam reliability with a reproducibility of 1.7 %. The absolute dose measured in the phantom irradiated by the seven participating centres has shown an error inferior to the standard tolerance limits (± 5 %), for most of participating centres. The relative dose measurements performed at Nancy and by the Equal-Estro laboratory allowed defining the most adequate parameters for gamma index (5 %/2mm--with at least 95 % of pixels satisfying acceptability criteria: γ<1). These parameters should be independent of the film analysis software. CONCLUSION: This work allowed defining a dosimetric external quality control for CyberKnife(®) systems, based on a reproducible irradiation plan through measurements performed with thermoluminescent dosimeters and radiochromic films. This protocol should be validated by a new series of measurement and taking into account the lessons of this work.

[Recommendation of the working group commissioned by the French Nuclear Safety Authority on stereotactic radiation therapy]. / Avis du groupe de travail missionné par l'Autorité de sûreté nucléaire concernant la radiothérapie stéréotaxique.

PURPOSE: At the request of the French nuclear safety authority (Autorité de Sûreté Nucléaire, ASN) a working party of multidisciplinary experts was initiated to elaborate a report regarding propositions for the clinical practice of stereotactic radiation therapy and the related medical physics. MATERIAL AND METHODS: Several stereotactic radiation therapy experts were audited by the working party, especially neurosurgeons and neuroradiologists, as well as radiation oncologists, medical physicists and radiation technologists. An international survey was conducted looking at legal requirements and guidelines concerning stereotactic radiation therapy. A national survey was conducted in France among 29 departments performing stereotactic radiation therapy. The working party report was submitted for advice to the permanent group of medical experts of ASN. RESULTS: Among the 13 countries who responded, very few have legal documents. Some of them are stating that stereotactic radiation therapy must be performed in a radiotherapy department and only by well-trained professionals. Guidelines describing the role of each participant have been published in the USA. In France, stereotactic radiation therapy is performed with dedicated machines or adapted linear accelerators. In 2009, within the 29 departments, 4247 patients were treated with stereotactic radiation therapy representing 4% of the patients treated with external beam radiation therapy. Intracranial lesions were: 3383 and extracranial: 864. The working party of multidisciplinary experts made 7 recommendations. The first one saying that stereotactic radiation therapy must be considered as a radiotherapy. The permanent group of medical experts is asking to modify the "décret du 19 mars 2007" regarding "radiosurgery". CONCLUSION: The medical benefit of stereotactic radiation therapy is well admitted and it is an increasingly used technique. This work through practical guidelines and legal propositions intends to promote a well-controlled development of this radiotherapy technique.

[Dosimetry comparison of irradiation with conformal radiotherapy, intensity modulated radiotherapy, conformal radiotherapy in stereotactic conditions and robotic stereotactic radiotherapy for benign brain tumours]. / Comparaison dosimétrique de la radiothérapie conformationnelle, la radiothérapie conformationnelle avec modulation d'intensité, la radiothérapie conformationnelle en conditions stéréotaxiques et la radiothérapie en conditions stéréotaxiques robotisée des tumeurs cérébrales bénignes.

PURPOSE: To compare several techniques in order to determine the best treatment for benign brain tumours. METHODS AND PATIENTS: A retrospective study was performed for five patients who received 3D-conformal radiotherapy, intensity modulated radiotherapy or CyberKnife(®). These patients had a meningioma, a pituitary tumour, a craniopharyngioma or a neurinoma. In each case, these treatment plans were optimised and compared with the three other dosimetries. Radiobiological or positioning parameters were evaluated, as well as dosimetric parameters, in order to compare treatments with different characteristics. RESULTS: The dosimetric parameters showed that the choice of treatment seemed to be determined mostly by tumour size, shape and proximity with organs at risk (not tumour localisation). Whereas the results showed no significant deviations with regards to the radiobiological parameters. Therefore, with these parameters, it was difficult to give priority to a treatment. CONCLUSIONS: With regards to benign brain tumours of medium or large size, intensity modulated radiotherapy seemed the recommended treatment. It enabled to obtain a good ratio between efficacy and toxicity for tumours that are really close to organs at risk. Concerning small benign brain tumours, the CyberKnife(®) was probably the best treatment.

[High dose rate vaginal brachytherapy in endometrial cancer after surgery]. / Curiethérapie postopératoire du fond vaginal de haut débit de dose dans le cancer endométrial.

PURPOSE: This study aimed at analyzing the evolution and type of recurrence in patients treated for stage I endometrial carcinomas, in order to define the respective roles of adjuvant radiotherapy and brachytherapy. PATIENTS AND METHODS: This monocentric retrospective study was conducted at Centre Alexis-Vautrin, Nancy, France, between January 1995 and December 2000 on all the patients surgically treated for an endometrial cancer, and then treated with high dose rate vaginal brachytherapy. The brachytherapy was delivered in two or three fractions of 7 Gy at 5 mm from the applicator. RESULTS: In the good prognosis group, the specific and overall survivals at 5 years were respectively 96.5 and 94.2% with no local recurrence demonstrated. In the intermediate prognostic group, the specific and overall survivals at 5 years were respectively 88 and 85%, with six locoregional recurrences observed among those who did not undergo lymphadenectomy; the overall survival at 5 years was significantly decreased in the absence of external radiation. In the group of poor prognosis (stages II and III), the specific survival at 5 years was respectively 72.8 and 67 %, and the overall survival at 5 years 66.7 and 56.4%. CONCLUSION: Results for local control and survival as well as for tolerance were good. So we have decided to deliver high rate brachytherapy for all intermediate or poor prognosis patients and we have abandoned pelvic radiotherapy for good prognosis tumours (stages IA: no myometrium invasion with grade 3 and >50% of myometrium invasion with grades 1 and 2), whatever the lymph nodes surgery they had. We now propose pelvic radiotherapy only for intermediate prognosis tumours (such as IA>50% of myometrium invasion with grade 3 and IB stages), if patients did not have any lymphatic surgery, or for bad prognosis tumours.

[Safety and quality assurance management in radiation oncology "what is the role for qualiticians?": example of the Centre Alexis Vautrin]. / Management de la qualité et de la sécurité en radiothérapie "Quel rôle pour les qualiticiens ?": exemple au centre Alexis-Vautrin.

Since 2007, the Centre Alexis-Vautrin Cancer Institute in Nancy began its safety and quality assurance management policy in the department of radiation oncology. This development induced a collaborative workflow between the quality unit and the department of radiation oncology, with a definition of the responsibilities. The quality unit provides its methodology for the quality assurance, the professionals of the radiation oncology department their expertise. In parallel, a quality referee was nominated in the radiation oncology department to implement the projects for improvement, linked with the quality assurance unit, and under the control of the radiation oncology department staff.

[Repositioning accuracy of cerebral fractionated stereotactic radiotherapy using CT scanning]. / Evaluation par tomodensitométrie du repositionnement en radiothérapie stéréotaxique fractionnée cérébrale.

PURPOSE: To evaluate the accuracy of patient repositioning in fractionated cerebral stereotactic radiotherapy using a Brain Lab stereotactic cranial mask in conjunction with standard dental fixation. PATIENTS AND METHODS: Fifty planning and checking CT scans were performed in 25 patients. The check CT scan was performed before or after one of the three sessions of treatment. Coregistration to the planning CT scan was used to assess alignment of the isocentre to the reference markers. The relative position of the PTV with regard to isocentre allowed us to determine its total displacement (3D vector). RESULTS: Mean isocentre translations (+/-SD) taking into account direction were -0.01+/-0.7, -0.2+/-1.3 and 0.07+/-0.5mm in mediolateral, craniocaudal and anteroposterior directions respectively. Mean rotations (+/- SD) were -0.02+/-0.6, -0.08+/-0.3 and -0.1+/-0.3 degree in mediolateral, craniocaudal and anteroposterior axes respectively. Mean overall PTV displacement was 1.8+/-1.5mm. PTV displacement was smaller than 2 and 3mm in 19/25 and 23/25 patients respectively. CONCLUSION: The accuracy of patient positioning using a stereotactic cranial mask system is similar to those reported in the literature and shows a satisfactory reproducibility with a standard dental fixation.

[Radiosurgery of cerebral arteriovenous malformations: a prescription algorithm]. / Radiochirurgie des malformations artérioveineuses cérébrales : élaboration d'un algorithme de prescription.

PURPOSE: To study prognostic factors of obliteration and risk factors of brain radiation necrosis in order to propose an algorithm for radiosurgery prescription for cerebral arteriovenous malformations (cAVM). MATERIAL AND METHODS: One hundred and seventy-nine patients were analysed. Radiosurgery delivered 6 or 10 MV X-rays by arc therapy in 84% of cases, or by fixed field in 16% of cases using two different micro-multileaf collimators (micro-MLC). Follow-up consisted of screening radiation necrosis by MRI every 6 months, and assessing local control by arteriography every 2 years. Obliteration was defined as at least 95% reduction of cAVM volume. Cox proportional hazard model was used to evaluate the local control and the appearance of radiation necrosis over time. RESULTS: Local control rate was 82.7% with the mean follow-up of 3.1 years (0.5-11). Significant prognostic factors were: simple nidus (RR=2.8, p<0.0001), number of embolizations before radiosurgery below 4 (RR=2.9, p<0.0001), prescribed dose to the periphery of at least 18 Gy (RR=2, p=0.0002), nidus volume below8cm(3) (RR=1.9, p=0.0002), and number of table positions below six (RR=1.4, p=0.05). Radiation necrosis rate was 11.2% with a mean time to onset of 18 months. Significant predictive factors were: fixed field versus arc therapy (according to MLC RR=9.1, p<0.0001, and RR=15.1, p=0.01), age below 30 years (RR=2.5, p=0.04), depth of cAVM greater than or equal to 7 cm (RR=7.6, p=0.008), and volume of brain tissue covered by the 12 Gy isodose (V12 Gy) of at least 11 cm(3) (RR=7.8, p=0.05). CONCLUSION: A radiosurgery prescription algorithm taking into account the prescribed dose to the periphery (> or = 18 Gy) and reduction of V12 Gy was elaborated from these data.

[Long-term results and prognostic factors of squamous cell carcinoma of the anal canal treated by irradiation]. / Résultats à long terme et facteurs pronostiques des carcinomes épidermoïdes du canal anal traités par irradiation.

PURPOSE: To analyze the prognostic factors of loco regional control (LRC), specific survival (SS) and sphincter conservation (SC) of patients treated by curative and conservative irradiation for an epidermoid cancer of anal canal in our institution. PATIENTS AND METHODS: From 1976 to 2005, 286 patients (pts) were treated by exclusive radiotherapy (180 pts) or chemo-radiotherapy (106 pts) followed by a brachytherapy boost (233 pts) or external beam radiotherapy boost (24 pts). Forty-three pts were stage I, 154 stage II, 31 stage IIIA and 53 stage IIIB. RESULTS: The mean follow-up was 65 months (range: 1.3-250 months). The 5-years-overall survival and SS rates were 66.4% and 78.1% respectively. In multivariate analysis, tumor size (>or=40 mm) [RR=2.1], node involvement (RR=2.4), and poor response (<75%) to first course irradiation [RR=1.9], local relapse (RR=4.5) and distant metastases were factors of poor prognosis for SS. Five-years-LRC were 71.5% (88% for stage I, 69% for stage II, 77%, for stage IIIA and 60% for stage IIIB). Prognosis factors of LCR were tumor size (RR=2.5), response to first course of irradiation (RR=2.9). SC was 71% at 5 years. Prognosis factors of SC were tumor size (RR=1.9) and response to first course of irradiation (RR=2.4). CONCLUSION: The results of this series are similar to those of the literature. As well as initial tumor extension, response to first course of irradiation was found as prognostic factor on LCR, SS, SC. Our results are similar to other series and brachytherapy seems not to be deleterious. Its impact to local control remains to be evaluated.

[Conformal radiotherapy in cancer of the upper aerodigestive tract]. / Radiothérapie conformationnelle des cancers des voies aérodigestives supérieures.

The outcome of head and neck malignancies is closely related to the achievement of local tumor control. The occurrence of severe late complications is the consequence of the anatomic vicinity between dose-limiting normal tissues and the tumor, thus reducing the curative potential of radiotherapy. Conformal radiotherapy is presently actively investigated as a way to improve the dose distribution in head and neck malignancies (especially when originating from the nasopharynx or the sinuses) while protecting healthy organs. Such an approach requires a chain of sophisticated procedures, including efficient quality assurance programs, in order to achieve the proper degree of safety. The relatively limited clinical studies published to-date have already confirmed the advantage of conformal radiotherapy in terms of dose delivery. The development of beam intensity modulation is likely to further contribute to the improvement of the therapeutic ratio.

[Dosimetry of small-size photon beams]. / Dosimétrie des faisceaux de photons de faibles dimensions.

A high performance standard radiotherapy treatment unit could be used to perform stereotactic radiosurgery. The dosimetric aspects of stereotactic irradiation with small size photon beams (energies from 5 to 25 MV produced by electron linear accelerator or gamma-rays produced by cobalt-60 treatment unit) are analyzed. The diameter of circular beams used are 5 to 40 millimeters wide at the isocenter of the treatment unit. The dosimetry of small x-ray fields is complicated by two factors: the relationship between detector size and field size dimensions, and the lack of lateral electron equilibrium. The large dose gradients outside the beam's central axis require dosimetry techniques with higher spatial resolution. To determine the best dosimetry system for measurements at the beam's small focal point, particularly for measurement of the field size dependent on output factors, several different detectors were investigated: ionization chamber, silicon diode, diamond detector, thermoluminescent dosimeter, and film. Ionization chamber, which presents a sensitive volume smaller than 0.02 cm3, is the most commonly recommended detector for field diameter above 8 mm. Current representative examples of dosimetric measurements for different x-ray energies, including percent depth dose, tissue maximum ratios, beam profiles (off axis ratios), and output factors, are presented and discussed. As well, the dosimetric characteristics of small photon beams are detailed.

[Optimization of dose distribution of radiation in cancers of the cavum: association of an expert-system and a mathematical algorithm]. / Optimisation de la balistique d'irradiation des cancers du cavum: association d'un système-expert et d'un algorithme mathématique.

Optimization of radiation therapy in nasopharyngeal carcinoma is particularly complex due to both the proximity of at risk organs and the high dose that has to be delivered. To obtain an optimal dose distribution, a knowledge-based optimization technique has been designed that associates an expert-system, named CAVCAV, with numeric optimization (gradient projection method). Based on clinical and physical criteria, CAVCAV determines the geometric characteristics of the radiation fields (beam direction, location and shape of the shielding blocks) for the three stages of radiation therapy of nasopharyngeal carcinomas. Stage 2-treatment fields proposed by CAVCAV, though not perfectly adapted to the patient, are mathematically (beam weights, beam directions, isocenter position) and geometrically (adaptation of fields and shape of blocks by virtual simulation) optimized.