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In an earlier presentation, Ms Fanneke van den Boomen, from theCatharina Hospital, Eindhoven, The Netherlands, described how sheand her colleagues had compared results from two different kinds ofCT scan to see which could more accurately estimate safety marginsfor radiotherapy treatment where breathing motion was involved.They compared the results from 3D and 4D treatment-planning CTscans of 50 patients with lung tumours and found that the morerecent 4D scans provided better results in cases where large tumourmotion was involved. "In a conventional 3D scan," Ms van den Boomen explained, "the scanis taken with the patient in the treatment position, but not takingbreathing motion into account. Due to the fact that it takes aroundtwo minutes to perform the scan, the result is blurred due to themotion of the tumour. With 4D scanning you can account forbreathing because the software creates a number of datasets atdifferent phases of the breathing cycle, thus freezing the tumourin a certain position." 4D scanning equipment has only become available recently, andtherefore the number of institutes using it is still limited.However, the researchers say, the results are so impressive thattheir hospital is now performing it routinely in cases where thereis large tumour movement. "The results from this study have shown that we can safely applythe 'mid-ventilation' concept, where we only irradiate part of thetumour trajectory instead of the entire volume in which the tumourresides during a breathing cycle. Thus we can reduce treatmentvolumes, with the result that patients have fewer complications,"said Ms van den Boomen. In another study presented to the conference, Gauthier Bouilhol,M.Sc, from the Centre L on B rard, Lyon, described how he andcolleagues from CREATIS (CNRS UMR5220, Inserm U1044) have developeda model to adjust the method currently used for the calculation ofsafety margins to account for respiratory motion asymmetry duringradiotherapy. "When a patient breathes during radiotherapy treatment," Mr.Bouilhol explained, "the tumour may also move. The normal way ofcalculating the treatment margins to compensate for potentialerrors is based on a symmetrical model. But if tumour motion isasymmetric the model is wrong." The researchers suggest a new model that takes into account thedifferences between the two margins involved in inhale and exhalemotion. "We believe that our model, once clinically validated, willprovide a more accurate assessment of the area which is required tobe treated with radiation, and this will improve both safety andefficacy for patients," Mr. Bouilhol said. Dr. N ria Jornet, medical physicist from the Hospital de la SantaCreu i Sant Pau, Barcelona, and chair of the ESTRO-31 scientificprogramme committee said: "Organ motion due to physiologicalprocesses such as breathing poses a challenge in highly accurateradiation therapy. With the advent of technological advances suchas 4D imagers, which allow making 'cine' images of internal organmotion, and treatment units that can synchronise radiation with theorgan movement this motion can be monitored and accounted for.Nowadays we are not only able to know where the tumour is in eachmoment but also have methods to hit it with a millimetric accuracy. "These three abstracts are a good example of how breathing motionis managed using different approaches either by reducing motion byirradiating in deep inspiration breath hold which also exploitslung inflation to spare normal tissues, or by personalising safetymargins around the tumour so that we are sure that the tumour willbe correctly irradiated in all breathing phases. Regardless of themethod used to manage motion, image guidance during treatment isneeded, as is shown in the study by Mrs. van den Boomen." Additional References Citations. I am an expert from bottle-fillingmachine.com, while we provides the quality product, such as Bottle Blowing Machine , Sterilization Equipments, Juice Filling Machine,and more.
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