Development of elements of 3D planning program for radiotherapy Graphical editor options  automated enclose of contour  correction of intersections  editing of drawing structure  calculating of external contour  calculating sections of structures on anterior and coronal planes Program includes a developed graphical editor which allows drawing anatomical structures on axial CT slices. Main application window Drawing anatomical structures

Anatomical structures sections on anterior view Anatomical structures sections on coronal view

Calculation of aperture of individual collimator Each treatment plan contains one or more sub-plans, so-called treatment prescriptions. Each prescription contains one or more beams (fields). After drawing of anatomical structures program calculates aperture of individual collimator for each beam. Simple round collimator Simple rectangular collimator Individual collimator Multileaf collimator

Calculation of 3D dose distributions A pencil beam algorithm for calculation of 3D dose distribution developed in medical technical complex was incorporated to the program. Calculated dose distribution in a water phantom

Verification of Patient Positioning in Proton Therapy based on Digital X-ray Images Necessary condition! If the proton beam has not the accurate way through the target, we have no full irradiation of important volume of the target and on the other hand we can find over irradiation of critical structures of the brain with located near the target.

Production of the digital X-ray image by digitizer REGIUS170 of Konica Minolta Company takes 20 seconds

Digital reconstruction radiogram (DRR) X-ray image

This program is the first version. In this version the superposition can’t be made without an operator. The next version of the program is being written now and it will have a function for the automatic superposition.

DEVELOPMENT OF A HARDWARE-SOFTWARE SYSTEM FOR A DYNAMIC IRRADIATION METHOD IN PROTON THERAPY Spread-out Bragg peak (SOBP) formation in a passive beam spreading technique in the proton radiation therapy can be conditionally divided into two different methods: irradiation with fixed and variable SOBP. Problem of Fixed SOBP One of the major limitations in the conventional proton therapy technique using range modulation device such as a Ridge Filter, a Fixed Range Shifter and a collimator, is that a fixed width of the SOBP has to cover the 3D target volume. Therefore, it is usually inevitable for the fixed SOBP to extend to healthy tissues. In this case 1/3 of a treated volume is out of the target Idea of Variable SOBP The dynamic irradiation (or layer-stacking method) was proposed to resolve problem of excessively irradiation of healthy tissue in the Fixed SOBP method by producing a variable SOBP without requiring a drastic modification of the conventional beam delivery system. In this case a treated volume is almost equal to the target volume

In the dynamic irradiation technique, a target volume is virtually divided into several thin layers in the depth direction using a Multi-Leaf Collimator and a Dynamic Range Shifter. These imaginary individual layers are treated with the conventional non-modified proton beam, different beam ranges, and conformal fields. Dynamic Irradiation System

Multi-Leaf Collimator Leaf material – steel Number of leaves - 60 Max field size – 100x100 mm Height of one leaf – 2,9mm Individual leaf travel – 100mm Average transmission ~3% max Dynamic Range Shifter Material of the shifter – PMMA Max. thickness at the beam axis – 108mm(H2O) Output scattering angle of about 17,0mrad or 1,0degree

Dynamic Range Shifter and MLC are synchronously controlled with the dose delivery.

* Kanematsu et al.: Treatment planning for the layer-stacking irradiation system. Clinical Effectiveness (expected results) Dose distribution for a tumor in the bone and soft tissue region*; Target contour and the isodose lines are overloaded on the patient CT image for (a) the dynamic irradiation and (b) the conventional irradiation. The yellow line shows the target contour while the isodose lines are in colors of the corresponding dose-percentage numbers shown. Generally effective for – large target volume – single or a few beam directions – small organ motion