Locandina commerciale

brochure DISO fronte.jpg

Following the EURATOM 97/43 recommendation, since 2000 is operative in

Italy the law D.L.vo 187/00 about the radioprotection of the patients undergone at

medical radio exposition. In radiotherapy the number of Quality Controls

is increasing as function of the treatment complexity and in some cases the workload is

responsible of their partial absence. Moreover in this field severe incidents have

been recently reported by the media.

Tumor Control

Probability

Opinion of many physicists is that a control during the treatment using a dedicated

software for the in-vivo dosimetry (IVD) could reduce dosimetric errors. This mean a major presence of physicists during the radiotherapy treatment execution, where actually there is a

general absence of this professional component.

Moreover the IVD is one of the best ways to gain experience to prevent errors when

introducing new radiotherapy techniques.

All the current IVD supply estimations of the real delivered

doses in patient . Indeed even the more complex clinical IVD procedures use

initial reference CT scans (used for the plan) to reconstruct the x-ray fluence to use in a second step for the recomputation of the dose in the same reference CT scans.

Then if the patient’s shape or setup are changed, the reconstructed fluence is not accurate and so the reconstructed doses in the patient.

Only a wide-spread use of image guided radiation therapy could assure more accurate daily dose distributions, but also higher doses at normal tissues and time consumed.

For these reasons it is our opinion that accually, IVD tests in quasi real time can supply these useful clinical warnings to activate quality controls needed to remove the causes of errors.

THE DISO PROGET, SUPPORTED BY “ISTITUTO NAZIONALE di FISICA NUCLEARE” INFN, AND UNIVERSITA CATTOLICA S.C. ROMA , INTEND TO DEVELOPE SOFTWARE FOR THE IN-VIVO DOSIMETRY CONTROL USING aSi-EPIDs

website: www.infndiso.altervista.org

Parma Azienda Ospedaliera Universitaria

Firenze Centro Oncologico Fiorentino

Cagliari Presidio Oncologico Businco

Viterbo Ospedale Belcolle

Roma Campus Biomedico

Roma Università Cattolica

Campobasso Fondazione Giovanni Paolo II

Rionero in Vulture Ospedale Oncologico Regionale CROB

Staff of physicists Associated at INFN for the DISO Project

website: www.infndiso.altervista.org ommerciale

DISO AIMS

Easy implementation on linacs Varian, Elekta e Siemens

The tests can be obtained in quasi real time due to the interfacing with the R&V of the Center

Locandina commerciale

brochure DISO fronte.jpg

THE SOFTDISO-3DCRT SUPPLIES TWO TESTS:

1) The first test is the ratio between the reconstructed dose at the isocenter point, and that planned by TPS

R = Diso/ Diso,TPS

acceptance criteria: 0.95 ≤ R ≤ 1.05

2) The second test is a analysis test between a reference EPID image acquired at the first fraction and the others obtained during the successive fractions. This is a suitable tool to find causes of incorrect beam delivery reproducibility.

reference current distribution image image of points in

disagreement

P <1

The reference EPID image (REI) is selected only if 1) it is verified the good patient setup, generally at the first

fraction therapy using Portal Visual Inspections; 2) the ratio R is within the acceptance criteria of 5%.

The analysis (Low et al. 1998) is determined for each pixel of the 2D-image and supplies the agreement between the REI signal and that on the current image with an acceptance criteria of 5% and a distance-to-agreement 3 mm .

A perfect agreement means a percentage of points

P <1 = 100% (with <1).

Our experience suggests a pass-rate with P <1 ≥ 90%

and a mean value < 0.5

The acceptance criteria of all the dosimetric indexes :

Acceptance-criteria: 0.95 ≤ R ≤ 1.05 Acceptance-criteria of 5% and a distance-

to agreement 3 mm for P <1

and -mean value

can be changed in the SOFTDISO-3D-CRT

by the user