The 2D-ARRAY seven29 A new way of dosimetric verification of - PTW

Fig. 21 shows again the verification results. The typical fields of breast IMRT plans are extremely
modulated with large central low-dose areas to spare the lung. Therefore, some parts of gamma
>1 have to be accepted again. Note that the spatial resolution of the 2D-ARRAY seven29 is good
enough, even for such highly modulated IMRT fields.
7. Conclusion
The 2D-ARRAY seven29 is a very reliable tool for the fast and precise verification of IMRT fields.
Together with the analysis software VeriSoft, even complex IMRT treatment plans can be verified
and documented within approximately one hour. Because air-filled ion chambers are used, no
complicated calibration procedures are necessary; the system is always ready for high-precision
measurements. The effective spatial resolution of the 2D-ARRAY is sufficiently high to obtain
reliable results even for highly modulated IMRT fields.
The dosimetric verification of IMRT fields is an important part of the routine quality assurance
package for IMRT treatments. The 2D-ARRAY and VeriSoft provide a reliable and easy-to-use tool
for that purpose.
Additionally the 2D-ARRAY, in combination with the software MultiCheck, can be used for daily
check of the constancy of main beam parameters of the linear accelerator.
8. Literature
[1] Intensity Modulated Radiation Collaborative Working Group, Intensity-modulated
radiotherapy: current status and issues of interest. Int. J. Radiation Oncology Biol. Phys.
51: 880-914 (2001).
[2] Van Esch A., Bohsung J., Sorvari P., Tenhunen M., Paiusco M., Iori M., Engström P,
Nyström H, Huyskens D. Acceptance tests and quality control (QC) procedures for the
clinical implementation of intensity modulated radiotherapy (IMRT) using inverse
planning and the sliding window technique: experience from five radiotherapy
departments. Radiother. Oncol. 65 (2002) 53-70.
[3] Low, D., Harms, W., Mutic, S., Purdy, J. A technique for the quantitative evaluation of
dose distributions, Med. Phys. 25 (1998) 656-661.
[4] Depuydt, T., Van Esch, A., Huyskens, D. A quantitative evaluation of IMRT dose
distributions: refinement and clinical assessment of the gamma evaluation. Radiother.
Oncol. 62 (2002) 309-319.
[5] Böhmer, D., Bohsung, J., Eichwurzel, I., Moys, A., Budach, V. Clinical and physical
quality assurance for intensity modulated radiotherapy of prostate cancer. Radiother.
Oncol. 71 (2004) 319-325.
Text and pictures by courtesy of
Dr. Jörg Bohsung
Charité Universitätsklinikum
Schumannstr. 20/21
10117 Berlin
D742.208.0/0 2004-06
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