Respiratory motion management for external radiotherapy treatment.

We present the update of the recommendations of the French society of oncological radiotherapy on respiratory motion management for external radiotherapy treatment. Since twenty years and the report 62 of ICRU, motion management during the course of radiotherapy treatment has become an increasingly significant concern, particularly with the development of hypofractionated treatments under stereotactic conditions, using reduced safety margins. This article related orders of motion amplitudes for different organs as well as the definition of the margins in radiotherapy. An updated review of the various movement management strategies is presented as well as main technological solutions enabling them to be implemented: when acquiring anatomical data, during planning and when carrying out treatment. Finally, the management of these moving targets, such as it can be carried out in radiotherapy departments, will be detailed for a few concrete examples of localizations (abdominal, thoracic and hepatic).

[Stereotactic radiotherapy for stage I and II lung cancer: a study of 33 patients]. / Radiothérapie en conditions stéréotaxiques dans les cancers bronchiques de stades I et II : résultats d'une série de 33 patients.

PURPOSE: Surgery is the main treatment of early stage non small cell lung cancer. However, in inoperable patients, the treatment is usually conventional radiotherapy. Results are poor and acute toxicity is severe. Stereotactic body radiation therapy provides better results in terms of local control and toxicity. Our purpose was to evaluate the clinical outcomes of patients with primary lung tumours treated by stereotactic body radiation therapy using a stereotactic body frame at the Orléans Regional Hospital. PATIENTS AND METHODS: Between June 2000 and December 2007, 33 patients with stage I and II non small cell lung cancer were treated by stereotactic body radiation therapy. Breathing control was obtained by passive diaphragm control. Two CT-scans were performed 1 week apart to determine the accuracy of patient repositioning and define target volumes. Five or six fields were set up to achieve a conformal dose distribution. According to tumour size, a total of 50 or 40 Gy was delivered in 10 fractions. RESULTS: Mean patient age was 70 years. Median follow-up was 25 months. Ten patients with a complete response are still alive. Eight patients have died from local progression, eight from metastasis, and six from comorbidity. Median disease-free survival was 22.6 months. No acute toxicity up to grade II (CTC AE 3.0) was observed. None of the patients still alive has developed any complications. CONCLUSION: In patients who cannot undergo radical surgery, stereotactic body radiation therapy using a sterotactic body frame is well-tolerated and seems to be an efficient treatment method.

Accuracy of alignment in breast irradiation: a retrospective analysis of clinical practice.

The objective of the study was to determine the accuracy of patient positioning in radiotherapy for breast cancer. Portal images were obtained using a fast electronic megavoltage radiotherapy imaging system in 30 cases of breast cancer. Quantitative analysis of 530 megavolt portal images and comparison with 30 digitized simulation films were performed. Five linear measurements were taken for each simulation and verification film. Central lung distance (CLD) is the distance from the dorsomedial beam edge to the inner thoracic wall in the central plane of the beam. Cranial lung distance (CrLD) is the distance from the dorsomedial beam edge to the inner thoracic wall in the plane of the beam at 4 cm from the central plane. Central beam edge to skin distance (CBESD) is the distance from the skin to the ventrolateral beam edge in the central plane of the beam. The central irradiated width (CIW) is defined as the distance from the dorsomedial beam edge to the skin. The craniocaudal distance (CCD) is defined as the distance from a particular landmark to the caudal field border. Concerning patient position in the field, mean standard deviations of the difference between simulation and treatment images were 3.9 mm for the CLD, 3.2 mm at +4 cm, 3.6 mm for the CIW, 3.3 mm for the CBESD, 3.8 mm for the CCD. In 90% of all set-up for treatment, errors were less than 1 cm. The variation of the CLD was the largest set-up error. This parameter is clinically the most significant. Future treatment delivery should be improved by introducing patient positioning devices such as thermoplastic shells. The electronic portal imaging device (EPID) appears to be an adequate tool to study the accuracy of treatment set-ups like this.

[Retrospective analysis of the reproducibility of the daily set-up of the irradiation fields of cancer of the rectum using a megavoltage imaging system]. / Analyse rétrospective de la reproductibilité de la mise en place quotidienne des champs d'irradiation de cancer du rectum par imagerie de contrôle de haute énergie.

PURPOSE: To evaluate a ionization chamber on-line portal imaging system in routine clinical radiotherapy of rectum cancers. PATIENTS AND METHODS: Megavolt portal images were obtained using a fast electronic megavoltage radiotherapy imaging system in 13 cases of pelvic fields. A total of 208 portal images and 13 simulator films were used to determine the values of set-up deviations in the X-Z-directions of a fixed co-ordinate system, and of the rotation fields (R). RESULTS: Mean standard deviations of the difference between simulation and treatment images were 3.2 mm and 0.9 mm for X and Z, 3.6 mm for the rotation fault. The standard deviations were, respectively, 7.1 mm, 7.1 mm and 1.5 mm. The cumulative frequency distributions revealed that 80% and 95% of the absolute differences were less than 10 mm and 17.5 mm, respectively. CONCLUSION: These results indicate the difficulty of a reproducible daily set-up. A weekly control could be proposed in order to increase the quality of pelvic site treatment. The introduction of masks to improve the set-up is also discussed.

[Computed tomography option on simulator: a 14-month use at the Orléans hospital radiotherapy department]. / L'option scanneur sur simulateur: 14 mois d'utilisation dans le service de radiothérapie du CHR d'Orléans.

The purpose was to evaluate the use of the CT option for simulator during a 14-month period in the radiotherapy department. The CT option has been adapted on the Philips simulator SL23. The virtual tunnel diameter is 92 cm which allows slice acquisition regardless of the contention device used. This system is connected to the treatment planning system through an Ethernet link. Three fields of view are available which cover the standard radiotherapy use. Four hundred and twenty-seven patients benefited from this system over a 14-month period of use. The number of slices acquired per patient regularly increased. The use of the system was rapidly extended to all the standard treatments. Those slices were also used as additional information for these high technology treatments. The good quality of the images and the reliability of this system involved a rapid integration in the treatment preparation procedure. It will not replace the use of the scanner but will significantly improve the treatment quality.