- Email: [email protected]
1303 poster INTENSITY MODULATED RADIOTHERAPY (IMRT) SOLUTIONS FOR ANAL CANCER TREATMENT USING UK ACT-II SCHEDULE
S 488
IMRT: C LINICAL IMPLEMENTATION
Materials: The study was divided into three parts. In the first part CTVPTV margins were defined by matching portal images with reference images based on bony structures. We included nine patients who were treated on a BB device with a four field box technique in 2007-2008. Daily portal images were made in two directions (AP and LR). The random (σ ) and systematic (Σ) errors are determined with SPSS and are used in Van Herks margin recipe (van Herk et al, 2000) to calculate the margins in three directions. In the second part the correlation between the matches of two different radiotherapists (RTTs) was determined and portal images were matched with the reference images by two RTTs. Finally, both intra- and inter- fraction movement of the target volume also influences the necessary CTV-PTV margin. A literature survey has been performed to investigate this phenomenon. Results: For each direction 195 images were analyzed. The results were used to calculate systematic and random errors in three directions for each patient and the research group (table 1). The data were normally distributed and the correlation between the matches of the RTTs was very high (> 0,95) for the translations. For the rotations lower correlations were found (>0,67), probably because of the intrinsic sensitivity of the software used for matching. Application of Van Herks margin recipe leads to CTV-PTV margins of: 6,1 mm LR; 6,7 mm CC and 7,6 mm AP (table 1).
primary volume (1/10) (mean IMRT1 CI=2.35, IMRT2 =1.52, IMRT3=1.20). Similar OAR doses were observed for all plans. Mean (range) small bowel receiving V30 was 159(48-336)cc for IMRT1, 153(46-341)cc for IMRT2 and 145(0-347)cc for IMRT3.Smaller volumes of genitalia receiving 20Gy and 40Gy (mean V20=84.6cc and mean V40=16.5 cc) with IMRT3 compared to IMRT2 (97.3cc; 23.1cc respectively) and IMRT1 (103.6cc; 28.4cc respectively) were observed.The mean (range) normal tissue V5 was 88%(86-91%), 89%(85-95%) p=0.4 and 87%(84-90%) p=0.5 for IMRT1, IMRT2, and IMRT3 respectively. Conclusions: All IMRT techniques appear to be equivalent in terms of OAR dose despite the increase in conformality with the more complex phase2 IMRT plans. This surprising result is due to the fact that all the phase 2 volumes are small (for 9/10 less than 30% of Phase1) and is located away from all OARs. 3F conformal boost is an acceptable solution, and will be implemented as the standard approach at our centre. However, if there is inguinal node involvement the inverse planned phase 2 may provide benefit. 1304 poster INTENSITY MODULATED STEREOTACTIC TREATMENTS OF SMALL INTRACRANIAL TARGETS WITH ECLIPSE TPS AND MILLENNIUM MLC J. F. Calvo Ortega1 , J. Casals1 , E. Puertas1 , S. san José1 , S. Moragues1 1 H OSPITAL Q UIRÓN B ARCELONA, Department of Radiation Oncology, Barcelona, Spain
Taylor et al. (2008) reported that margins of 0,8 mm LR; 7,1 mm CC and 7,0 mm AP are needed to compensate for movement of the internal organs. Conclusions: The overall margins are obtained by a quadratic summation of the margins for patient movement and the margins for movement of the target volume. The conclusion was that CTV-PTV margins of 7 mm (LR), 10 mm (CC) en 10 mm (AP) are necessary for IMRT for patients with a gynaecological tumour treated on a BB device. A further reduction of the CTV-PTV margins depends mainly on the possibility of determining of and correcting for movement of the cervix and uterus on a daily basis. Therefore further research is needed. 1303 poster INTENSITY MODULATED RADIOTHERAPY (IMRT) SOLUTIONS FOR ANAL CANCER TREATMENT USING UK ACT-II SCHEDULE M. Hawkins1 , C. Brooks2 , Y. Lee2 , V. N. Hansen3 1 T HE R OYAL M ARSDEN NHS F OUNDATION T RUST, Clinical Oncology, Sutton, United Kingdom 2 T HE R OYAL M ARSDEN NHS F OUNDATION T RUST, Joint Department of Physics, Sutton, United Kingdom 3 R OYAL M ARSDEN H OSPITAL T RUST & I NSTITUTE OF C ANCER R ESEARCH, Joint Department of Physics, London, United Kingdom Purpose: ACT-II UK anal cancer chemoradiotherapy protocol delivers 50.4Gy at 1.8Gy/fraction/day(#) of radiotherapy (RT) in 2 phases: phase1 17# and phase2 11#. This schedule is not suitable for simultaneous integrated boost. The aim is to compare the dosimetry of the composite plan of increasingly complex IMRT for anal cancer treatment. Materials: Ten consecutive CT datasets of patients with anal canal cancer were identified. Phase1 planning target volume (PTV) included tumour, anal canal and inguinal, peri-rectal, and internal/external iliac nodes; while phase2 included primary tumour and involved nodes only (3/10 had involved inguinal nodes). Three types of composite phase1 and phase 2 IMRT plans were generated as follows: Phase1 inverse planned 7 fields (F) IMRT were the same for all plans. Phase 2 plans varied: IMRT1 3F conformal, IMRT2 forward planned 5F IMRT and IMRT3 inverse planned 5F IMRT. Coverage of phase 2 PTVs by 95% prescription isodose, homogeneity and conformity index (CI); the volume of OAR (small bowel, genitalia, and bladder) receiving more than 20, 30, and 40 Gy (V20, V30, V40) were compared. To characterise the low dose increase, normal tissue (body PTV) V5 was also studied. IMRT1 was the reference plan. Results: PTVs coverage and homogeneity indices for all 3 composite phase 1 and phase2 plans were similar: 95% PTV receiving >95% dose. However, the phase2 PTV CI improves with IMRT2 (mean=1.40) and IMRT3 (mean=1.21) when compared to IMRT1 (mean=1.80). This difference appears to be greater for patients with inguinal nodes (3/10) or an irregular
Purpose: To assess the feasibility of a commercial treatment planning system (TPS) for planning intensity modulated radiosurgery/radiotherapy (IMRS/IMRT) of small cerebral lesions by using a standard MLC. Materials: Eclipse TPS (version 8.0, Varian Medical Systems) was configured and commissioned for standard field sizes (down to 3 cm x 3 cm) for pencil peam convolution (PBC) algorithm and photon beams from a Varian Clinac 2100 CD equipped with a Millennium MLC (5 mm leaf width). Five treatments (non-IMRT) for small targets (diameter ranged from 1 to 3 cm) previously planned with a stereotactic-dedicated system (iPlan and m3 MLC, BrainLAB) were re-planned with Eclipse by using IMRT approach (Sliding Window). Coplanar and non-coplanar IMRS/IMRT plans were designed and inverse optimization process was used. Patient dose was calculated using PBC with the smaller grid size available for this model on Eclipse (1.25 mm).Clinical quality of Eclipse-based plans was assessed by comparing the target coverage (conformity index) with the iPlan-based ones. RTOG conformity index definition was used. Eclipse modulated plans were experimentally checked in two steps. Experimental verification of the IMRT-based plans was done in two steps. First, absolute dose verification at isocenter point was performed by mapping the original IMRT plan into a polystyrene phantom containing a calibrated ion chamber detector (PinPoint). Second, fluence of each individual IMRT beam was verified using Portal Dosimetry tool, with EPID detector placed at 180 cm from linac focus (resulting integrated portal images with 0.4 mm as pixel size at isocenter level). A 3% / 2 mm gamma criteria was established for fluence map verification. Results: Mean conformity index was 2.31 for m3-based plans and 1.99 for Millennium. Verifications of absolute dose for Eclipse calculations were within +/-3% in all the cases analysed. Planar fluence verifications met the 3%/2 mm criteria for 97% of pixel analysed (range: 93%-99%). Conclusions: Eclipse treatment planning system is suitable to produce clinically acceptable plans to treat small intracranial lesions by using Millennium MLC and IMRT delivery. The use of Portal Dosimetry tool allows an IMRT plan verification in a fast way before a single dose treatment delivery. 1305 poster INTENSITY MODULATED-TOTAL MARROW IRRADIATION (IM-TMI): FIRST CLINICAL EXPERIENCE B. Aydogan1 , M. Yeginer2 , A. Awan1 , M. Rank1 , P. Patel3 , B. Smith4 , D. Rondelli3 1 T HE U NIVERSITY OF C HICAGO, Radiation and Cellular Oncology, Chicago, USA 2 U NIVERSITY OF I LLINOIS, Molecular Biology of Oral Diseases, Chicago, USA 3 U NIVERSITY OF I LLINOIS, Department of Medicine, Chicago, USA 4 U NIVERSITY OF I LLINOIS, Radiation Oncology, Chicago, USA Purpose: To report the first ever clinical experience with fixed gantry intensity modulated-total marrow irradiation (IM-TMI) in a chemo-radiation preconditioning regimen. This is, to our knowledge, the first patient treatment case reported in the literature with this technique. Materials: A patient with a recurrent multiple myeloma was treated in our institutional phase I clinical trial for adjuvant linac-based IM-TMI and chemotherapy. The patient was immobilized using a customized whole body alpha cradle and was simulated with 5 mm-slice CT scanning from top of the head to the mid femur. All bones excluding the arms and lower extremities were contoured as the clinical target volume and a 3 mm margin was added to obtain the planning target volume (PTV). This method provided 7 mm to 12
IMRT: C LINICAL IMPLEMENTATION
Materials: The study was divided into three parts. In the first part CTVPTV margins were defined by matching portal images with reference images based on bony structures. We included nine patients who were treated on a BB device with a four field box technique in 2007-2008. Daily portal images were made in two directions (AP and LR). The random (σ ) and systematic (Σ) errors are determined with SPSS and are used in Van Herks margin recipe (van Herk et al, 2000) to calculate the margins in three directions. In the second part the correlation between the matches of two different radiotherapists (RTTs) was determined and portal images were matched with the reference images by two RTTs. Finally, both intra- and inter- fraction movement of the target volume also influences the necessary CTV-PTV margin. A literature survey has been performed to investigate this phenomenon. Results: For each direction 195 images were analyzed. The results were used to calculate systematic and random errors in three directions for each patient and the research group (table 1). The data were normally distributed and the correlation between the matches of the RTTs was very high (> 0,95) for the translations. For the rotations lower correlations were found (>0,67), probably because of the intrinsic sensitivity of the software used for matching. Application of Van Herks margin recipe leads to CTV-PTV margins of: 6,1 mm LR; 6,7 mm CC and 7,6 mm AP (table 1).
primary volume (1/10) (mean IMRT1 CI=2.35, IMRT2 =1.52, IMRT3=1.20). Similar OAR doses were observed for all plans. Mean (range) small bowel receiving V30 was 159(48-336)cc for IMRT1, 153(46-341)cc for IMRT2 and 145(0-347)cc for IMRT3.Smaller volumes of genitalia receiving 20Gy and 40Gy (mean V20=84.6cc and mean V40=16.5 cc) with IMRT3 compared to IMRT2 (97.3cc; 23.1cc respectively) and IMRT1 (103.6cc; 28.4cc respectively) were observed.The mean (range) normal tissue V5 was 88%(86-91%), 89%(85-95%) p=0.4 and 87%(84-90%) p=0.5 for IMRT1, IMRT2, and IMRT3 respectively. Conclusions: All IMRT techniques appear to be equivalent in terms of OAR dose despite the increase in conformality with the more complex phase2 IMRT plans. This surprising result is due to the fact that all the phase 2 volumes are small (for 9/10 less than 30% of Phase1) and is located away from all OARs. 3F conformal boost is an acceptable solution, and will be implemented as the standard approach at our centre. However, if there is inguinal node involvement the inverse planned phase 2 may provide benefit. 1304 poster INTENSITY MODULATED STEREOTACTIC TREATMENTS OF SMALL INTRACRANIAL TARGETS WITH ECLIPSE TPS AND MILLENNIUM MLC J. F. Calvo Ortega1 , J. Casals1 , E. Puertas1 , S. san José1 , S. Moragues1 1 H OSPITAL Q UIRÓN B ARCELONA, Department of Radiation Oncology, Barcelona, Spain
Taylor et al. (2008) reported that margins of 0,8 mm LR; 7,1 mm CC and 7,0 mm AP are needed to compensate for movement of the internal organs. Conclusions: The overall margins are obtained by a quadratic summation of the margins for patient movement and the margins for movement of the target volume. The conclusion was that CTV-PTV margins of 7 mm (LR), 10 mm (CC) en 10 mm (AP) are necessary for IMRT for patients with a gynaecological tumour treated on a BB device. A further reduction of the CTV-PTV margins depends mainly on the possibility of determining of and correcting for movement of the cervix and uterus on a daily basis. Therefore further research is needed. 1303 poster INTENSITY MODULATED RADIOTHERAPY (IMRT) SOLUTIONS FOR ANAL CANCER TREATMENT USING UK ACT-II SCHEDULE M. Hawkins1 , C. Brooks2 , Y. Lee2 , V. N. Hansen3 1 T HE R OYAL M ARSDEN NHS F OUNDATION T RUST, Clinical Oncology, Sutton, United Kingdom 2 T HE R OYAL M ARSDEN NHS F OUNDATION T RUST, Joint Department of Physics, Sutton, United Kingdom 3 R OYAL M ARSDEN H OSPITAL T RUST & I NSTITUTE OF C ANCER R ESEARCH, Joint Department of Physics, London, United Kingdom Purpose: ACT-II UK anal cancer chemoradiotherapy protocol delivers 50.4Gy at 1.8Gy/fraction/day(#) of radiotherapy (RT) in 2 phases: phase1 17# and phase2 11#. This schedule is not suitable for simultaneous integrated boost. The aim is to compare the dosimetry of the composite plan of increasingly complex IMRT for anal cancer treatment. Materials: Ten consecutive CT datasets of patients with anal canal cancer were identified. Phase1 planning target volume (PTV) included tumour, anal canal and inguinal, peri-rectal, and internal/external iliac nodes; while phase2 included primary tumour and involved nodes only (3/10 had involved inguinal nodes). Three types of composite phase1 and phase 2 IMRT plans were generated as follows: Phase1 inverse planned 7 fields (F) IMRT were the same for all plans. Phase 2 plans varied: IMRT1 3F conformal, IMRT2 forward planned 5F IMRT and IMRT3 inverse planned 5F IMRT. Coverage of phase 2 PTVs by 95% prescription isodose, homogeneity and conformity index (CI); the volume of OAR (small bowel, genitalia, and bladder) receiving more than 20, 30, and 40 Gy (V20, V30, V40) were compared. To characterise the low dose increase, normal tissue (body PTV) V5 was also studied. IMRT1 was the reference plan. Results: PTVs coverage and homogeneity indices for all 3 composite phase 1 and phase2 plans were similar: 95% PTV receiving >95% dose. However, the phase2 PTV CI improves with IMRT2 (mean=1.40) and IMRT3 (mean=1.21) when compared to IMRT1 (mean=1.80). This difference appears to be greater for patients with inguinal nodes (3/10) or an irregular
Purpose: To assess the feasibility of a commercial treatment planning system (TPS) for planning intensity modulated radiosurgery/radiotherapy (IMRS/IMRT) of small cerebral lesions by using a standard MLC. Materials: Eclipse TPS (version 8.0, Varian Medical Systems) was configured and commissioned for standard field sizes (down to 3 cm x 3 cm) for pencil peam convolution (PBC) algorithm and photon beams from a Varian Clinac 2100 CD equipped with a Millennium MLC (5 mm leaf width). Five treatments (non-IMRT) for small targets (diameter ranged from 1 to 3 cm) previously planned with a stereotactic-dedicated system (iPlan and m3 MLC, BrainLAB) were re-planned with Eclipse by using IMRT approach (Sliding Window). Coplanar and non-coplanar IMRS/IMRT plans were designed and inverse optimization process was used. Patient dose was calculated using PBC with the smaller grid size available for this model on Eclipse (1.25 mm).Clinical quality of Eclipse-based plans was assessed by comparing the target coverage (conformity index) with the iPlan-based ones. RTOG conformity index definition was used. Eclipse modulated plans were experimentally checked in two steps. Experimental verification of the IMRT-based plans was done in two steps. First, absolute dose verification at isocenter point was performed by mapping the original IMRT plan into a polystyrene phantom containing a calibrated ion chamber detector (PinPoint). Second, fluence of each individual IMRT beam was verified using Portal Dosimetry tool, with EPID detector placed at 180 cm from linac focus (resulting integrated portal images with 0.4 mm as pixel size at isocenter level). A 3% / 2 mm gamma criteria was established for fluence map verification. Results: Mean conformity index was 2.31 for m3-based plans and 1.99 for Millennium. Verifications of absolute dose for Eclipse calculations were within +/-3% in all the cases analysed. Planar fluence verifications met the 3%/2 mm criteria for 97% of pixel analysed (range: 93%-99%). Conclusions: Eclipse treatment planning system is suitable to produce clinically acceptable plans to treat small intracranial lesions by using Millennium MLC and IMRT delivery. The use of Portal Dosimetry tool allows an IMRT plan verification in a fast way before a single dose treatment delivery. 1305 poster INTENSITY MODULATED-TOTAL MARROW IRRADIATION (IM-TMI): FIRST CLINICAL EXPERIENCE B. Aydogan1 , M. Yeginer2 , A. Awan1 , M. Rank1 , P. Patel3 , B. Smith4 , D. Rondelli3 1 T HE U NIVERSITY OF C HICAGO, Radiation and Cellular Oncology, Chicago, USA 2 U NIVERSITY OF I LLINOIS, Molecular Biology of Oral Diseases, Chicago, USA 3 U NIVERSITY OF I LLINOIS, Department of Medicine, Chicago, USA 4 U NIVERSITY OF I LLINOIS, Radiation Oncology, Chicago, USA Purpose: To report the first ever clinical experience with fixed gantry intensity modulated-total marrow irradiation (IM-TMI) in a chemo-radiation preconditioning regimen. This is, to our knowledge, the first patient treatment case reported in the literature with this technique. Materials: A patient with a recurrent multiple myeloma was treated in our institutional phase I clinical trial for adjuvant linac-based IM-TMI and chemotherapy. The patient was immobilized using a customized whole body alpha cradle and was simulated with 5 mm-slice CT scanning from top of the head to the mid femur. All bones excluding the arms and lower extremities were contoured as the clinical target volume and a 3 mm margin was added to obtain the planning target volume (PTV). This method provided 7 mm to 12