June 14 2001
The Netherlands, Veenendaal, (14 June 2001) - Nucletron BV an international leader in radiotherapy announces the first clinical treatments combining the advanced inverse planning features of the PLATO treatment planning system with a Siemens linear accelerator. The Radiotherapy Department of the Virgen Macarena Hospital chose precise Intensity Modulation Radiation Therapy (IMRT) for the treatment of a patient with prostate cancer. The IMRT technique allows the hospital to improve local tumor control and decrease adverse side effects of the treatment. The treatment was designed using inverse treatment planning on the Nucletron PLATO system, allowing higher radiation dose to be given to the tumor and minimizing dose to radiation sensitive organs. IMRT is of interest in the treatment of prostate cancer because of the proximity of radiation sensitive organs that are difficult to avoid using conventional treatments. The treatment was the first to use the Nucletron planning system linked with a Primus linear accelerator from Siemens. The linear accelerator is equipped with a multi-leaf collimator (MLC) which shapes and modulates the intensity of the radiation beam during the treatment. The complex sequence of movements of the MLC is calculated on the PLATO planning system and transferred electronically to the control system of the linear accelerator. In IMRT, the treatment radiation beams are divided into a series of small fields, whose irregular shape is determined by the multi-leaf collimator. Accurately modelling the combined effect of many small, irregular fields in order to provide independent verification of the PLATO treatment planning system and treatment on the linear accelerator is a major step towards the routine application of this new treatment method. The clinical implementation of the IMRT technique, with a satisfactory degree of confidence, has been possible thanks to the scientific background of the research group of the Sevilla University (Medical Physiology and Biophysic Department) in close collaboration with the Virgen Macarena Hospital. This team has a wide experience on dosimetrical verification of complex Radiotherapy treatments by means of Monte Carlo calculation. Prof. Sanchez-Doblado and Dr. Leal said, "IMRT has been an exciting challenge to be checked in the new ITP module. The agreement between PLATO and Monte Carlo simulation has been very gratifying". Before performing treatments of this complexity, the hospital performed extensive verification tests on all elements of the planning and treatment chain. Dr. Rafael Arrans and Dr. Rosello of the Radiophysics Department, said "This [treatment] has been possible after verification of the high level of agreement between the calculation results given by the planning system and experimental methods carried out on anthropomorphic phantoms and simulated by Monte Carlo technique. A discrepancy of only 0.6% was found on the reference point between the dose proposed by PLATO and the measurement of an ion chamber." The close agreement between calculated and measured doses is in agreement with studies at other hospitals using Nucletron PLATO in combination with linear accelerators manufactured by Elekta and Varian. Dr. Luis Errazquin and Dr. Areste, from the Radiotherapy Department commented further, "In spite of its complexity, the application of this technique has not been so time consuming as to affect the normal number of treated patients at the linear accelerator." Nucletron also produces planning and treatment systems for brachytherapy, used for the treatment of prostate and other cancers. With brachytherapy, radioactive sources are positioned in the tumour to be treated, also giving a highly conformal dose distribution. "Nucletron is proud of its innovations in radiotherapy products that help fight cancer. The clinical use of PLATO’s inverse treatment planning software in Sevilla and other centres demonstrates that these new and complex techniques can be widely used to benefit patients," said Rudolf Scholte, Managing Director of Nucletron. The Sevilla group has a large number of international scientific publications related to Medical Physics and maintains close links and collaborations with important European radiotherapy centres. The group has organised several seminars and conferences. Currently they are organising a workshop on "Verification of IMRT" that will take place in Sevilla during September 2001.
About Nucletron Nucletron BV, Veenendaal, The Netherlands, is a worldwide leader in radiotherapy systems and thoracic imaging equipment for radiology and mass chest screening and specializes in some of the most innovative products used for cancer treatment. The company has 11 offices worldwide, including its corporate headquarter in the Netherlands. Nucletron has been a worldwide leader in remote afterloading brachytherapy for 25 years. Nucletron BV is a subsidiary of Delft Instruments, an international group of companies with about 1000 employees and annual sales of some EUR 180 million.