- Email: [email protected]
178 IMRT-planning of anal carcinoma
$90
Wednesday, September 28
178 I M R T - p l a n n i n g of anal carcinoma E. Lamers-Kuijper, B. Mijnheer, L. Dewit Department of Radiation Oncology, The Netherlands Cancer Institute, Antoni van Leeuwenhoek Hospital Amsterdam, The Netherlands Purpose: To improve dose homogeneity within the planning target volume (PTV) and to achieve normal tissue sparing in radiation treatment of anal carcinoma using IMRT. Method: Two case reports are presented in whom the radiation dose distribution in the pelvis is compared between a standard and an IMRT technique. Axial CT-slices are used for delineating the PTV. A standard 5-field technique is used, with one posterior and two lateral 18 MV photon fields for the posterior pelvis and two anterior electron fields for the inguinal lymph node area. A 7-field IMRT technique is applied including a simultaneous integrated boost. The prescribed total close to the regional lymph nodes is 49.5 Gy in 33 fractions of 1.5 Gy, whereas the dose to the primary tumor is 59.4 Gy in 33 fractions of 1.8 Gy. Results: Using the standard technique, an unacceptable large underdosage (up to 50%) is observed in the region between the pelvis and the inguinal lymph node area. In addition, unnecessarily high doses are given to surrounding normal tissues, most notably to the genital area. In contrast, with the IMRT technique a homogeneous dose distribution is obtained in the PTV (D95=98.9% for the inguinal lymph node area and 98.0% for the tumour area with a maximum dose of 104.5%) with significant sparing of the genital area (46% of the prescribed dose). Conclusion: IMRT with an integrated simultaneous boost for anal carcinoma is the radiation treatment technique of choice, in particular when the inguinal lymph nodes are included in the PTV.
Symposia
Wednesday, September 28
178 I M R T - p l a n n i n g of anal carcinoma E. Lamers-Kuijper, B. Mijnheer, L. Dewit Department of Radiation Oncology, The Netherlands Cancer Institute, Antoni van Leeuwenhoek Hospital Amsterdam, The Netherlands Purpose: To improve dose homogeneity within the planning target volume (PTV) and to achieve normal tissue sparing in radiation treatment of anal carcinoma using IMRT. Method: Two case reports are presented in whom the radiation dose distribution in the pelvis is compared between a standard and an IMRT technique. Axial CT-slices are used for delineating the PTV. A standard 5-field technique is used, with one posterior and two lateral 18 MV photon fields for the posterior pelvis and two anterior electron fields for the inguinal lymph node area. A 7-field IMRT technique is applied including a simultaneous integrated boost. The prescribed total close to the regional lymph nodes is 49.5 Gy in 33 fractions of 1.5 Gy, whereas the dose to the primary tumor is 59.4 Gy in 33 fractions of 1.8 Gy. Results: Using the standard technique, an unacceptable large underdosage (up to 50%) is observed in the region between the pelvis and the inguinal lymph node area. In addition, unnecessarily high doses are given to surrounding normal tissues, most notably to the genital area. In contrast, with the IMRT technique a homogeneous dose distribution is obtained in the PTV (D95=98.9% for the inguinal lymph node area and 98.0% for the tumour area with a maximum dose of 104.5%) with significant sparing of the genital area (46% of the prescribed dose). Conclusion: IMRT with an integrated simultaneous boost for anal carcinoma is the radiation treatment technique of choice, in particular when the inguinal lymph nodes are included in the PTV.
Symposia