Comparison of total DMU

At irradiation of breast, tangential beam with wedge filter is conventionally used. But wedge filter needs more DMU. It will cause increase of scatter doses ( and also maybe more exposure of skin ).

This case use 15deg wedge filter for tangential irradiation. It becomes about 1.5 times DMU of CFIMRT.

Tangential irradiation ( 15deg wedge filter )                                    CFIMRT                        

Tangential irradiation ( 15deg wedge filter )                  CFIMRT                            

   

DMU: 362.4                                             DMU: 231.8

DMU of conventional method is 156.3% compared with CFIMRT

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15 deg wedge filter ( see also About 'Wedge fielter' )

Tangential irradiation ( 15deg wedge filter )                  CFIMRT                            

BEV of CFIMRT

Comparison of exposure of a heart by tangential irradiation and CFIMRT

Tangential                                              CFIMRT

Tangential : The mean dose of left ventricle is 23.7Gy

CFIMRT: The mean dose of left ventricle is 21.74Gy

(BEV of CFIMRT)

For reference ( IMRT for breast iradiation )

Clinical experience in breast irradiation with intensity modulated photon beams.

Acta Oncol. 2005;44(5):467-74.

Cozzi L, Fogliata A, Nicolini G, Bernier J.

Medical Physics Unit, Oncology Institute of Southern Switzerland, Bellinzona, Switzerland.

Since 2002, twenty-five patients affected by breast cancer, for whom extensive lung/heart involvement was expected from conventional techniques, were irradiated with intensity modulated photon beams (IMRT). For 10 patients the internal mammary lymphatic chain was included in the target, 6 patients received treatment of the thoracic wall after mastectomy and 9 patients were treated after breast conserving surgery. Dose prescription ranged between 48.6 and 50 Gy at 1.8 or 2 Gy per fraction. The target volume (PTV) ranged from 194 to 2121 cm(3). For all cases a Dose Volume Histogram analysis has been conducted on omolateral lung, heart, contralateral lung and breast, healthy tissue and PTV. For PTV the volume receiving more than 90% of the prescribed dose (V(90%)) was 95.8+/-1.8% while V(107%)=5.3+/-2.8%. The mean dose computed for the heart was 10.4+/-2.9 Gy, for the omolateral lung: 13.3+/-2.8 Gy, for the contralateral breast: 3.4+/-1.8 Gy, for the contralateral lung: 4.6+/-2.7 Gy. For the omolateral lung V(20Gy)=23.1+/-7.0% and V(45Gy)=0.8+/-0.9 Gy. With a short mean follow up of 10.4 months, no pulmonary or cardiac complications were observed. IMRT proved to be technically feasible on a clinical basis for the treatment of the whole breast, including internal mammary chain, or of the thoracic wall after mastectomy.

 last modification date: 2006/04/05