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293 Quality indices of permanent prostate brachytherapy implants: inicial avaliation
Posters The source strength is calculated with the following formula: S~ = M * Ni * Kd , where M is the measurement readings in I~C, N~ is the calibrator factor in mGy.m2.h IA t Kd is the temperature-pressure correction factor. The AAPM TG 56 indicates a tolerance of 5% for individual source, and the AAPM TG 43 indicate a <2% accuracy tolerance in the well-type ionisation chamber. Results: The results for the 21 sources show an average difference in source strenght between the certificates and our measure of +0.6% (range of -2.7% and +3.9%). Conclusion: All measured sources are within the calibration certificate tolerance, and within the AAPM TG 56 recommended tolerance for individual HDR sources. This work allow us to alert PTW for the +/- 3% of uncertainty stated in the well-type ionization chamber calibration certificate. References: (1)R. Nath, L. Anderson, J. Meli, A. Olch, J. Stitt, J. Wiltiamson, "Code of practice for brachytherapy physics: Report of the AAPM Radiation Therapy Committee Task Group no. 56", Med. Phys. 24, 1557-1598, (1997). (2) j. Venselaar, et all, "A practical guide to quality control of brachytherapy equipment", ESTRO Booklet No. 8. (3)R. Nath et all., "Dosimetry of intersticial brachytherapy sources: Recommendations of the AAPM - TG 43", Med. Phys, 22 (2), pp. 209-234, 1995. (4) M. J. Rivard et all., "Update of AAPM Task Group n °. 43: A revised AAPM protocol for brachytherapy dose calculations", Med. Phys, 31 (3), pp. 633-674, 2004. 293 Q u a l i t y indices of p e r m a n e n t p r o s t a t e b r a c h y t h e r a p y implants: inicial a v a l i a t i o n
R. Pirraco~ A. Pereira Instituto Portugu#s de Oncologia Francisco Gentil, Medical Physics, Porto, Portugal I n t r o d u c t i o n : The evaluation of the quality indices is the best way (1'2) to provide detailed information about the adequate close coverage and a good uniformity with a minimum overdosage in 12sI permanent prostate brachytherapy implants. The objective of this study is to analyse the quality indices of implants in our institution treated with this technique since June of 2004. Methods and Material: Our method follow the recommendations of several organizations, such as ABS (1,2), AAPM (3) and ESTRO(4), and we use the AAPM TG 43 (5,6) formalism for dosimetry. The prescrived dose is 145 Gy. We make real-time intra-operative dosimetry with TRUS (transrectal ultrasound video acquisition), and Varian Variseed 7.1 dosimetry software. The sources are IsoSeed I25.S06 12sI from Bebig and we mix loose and strands implant seed technique. A X-ray image was taken the day after aplication for seeds count. A C T was performed four weeks after the implant for pos-implant dosimetric analysis and seeds count. Intra-operative and pos-implant dosimetry are assured by Dose Volume Histogram (DVH) analises, where we take several indices, such as Vl00, V150, V200 (the percentage of prostate volume receiving 100%, 150% and 200% of the prescibed dose), D90 (dose to 90% of the prostate volume), Duretra (urethra maximum dose), D10rectum (dose to 10% of rectum volume), and V80 (the percentage of prostate volume receiving 80% of the prescibed dose, in the pos-implant analise) (7). Results: Next tables shows the quality indices obtained in 28 patients, the first table refering to the day of the implant and the second table to the pos-implants values.
$137
Min Med Max
INTRA-IMPLANT Vol. N°. N°. Total Activity V100 V150 V200 D90 Durete~ D10Recum (crn 3) seeds needles Activity /seed (%) ( % ) (%) (Gy) (Gy) (Gy) (mCi) (mCi) 19.0 35 15 17.5 0.391 95.9 45.0 16.7 160.0 168.0 82.0 35.2 57.6 22.8 26.5 0.459 97.8 56.0 24.0 169.7 192.3 101.2 65.7 82 30 40.3 0.542 99.9 72.0 40.2 187.0 223.0 133.0
POS - I M P L A N T
Min Med Max
Vol. (cm 3) 19.8 38.4 65.4
V100 (°/o) 73.6 84.7 91.9
V150 (%) 32.2 50.2 66
V200 (%) 17.4 26.2 40.8
V80
(%)
90.6 103.0 123.9
D90 (Gy) 83.3 128.3 151
D10Re~um (Gy) 60.1 90.7 151.6
Conclusion: All values show that we have good target coverage, with acceptable doses to adjacent normal structures, and these results are reforced with the posimplant dosimetry analysis. This results show that we are in the good way, but however, we have to increase the number and wait for patients follow up, but primary results 3 months after implants show a normal PSA values for all patients. References: (1) Subir Nag et all, "ABS Recommendations for transperineal permanent brachytherapy of prostate cancer", Int. J. Rad. Biol. Phys, Vol. 44, No 4, pp. 789-799, 1999. (2) Subir Nag et all, "The ABS Recommendations for permanent prostate brachytherapy posimplant dosimetric analysis", Int. J. Rad. Biol. Phys, Vol. 46, No 1, pp. 221-230, 2000. (3) Yan Yu et all., "Permanent prostate seed implant brachytherapy: report of the AAPM - TG 64", Med. Phys, 26 (10), pp. 2054-2076, 1999. (4) D. Ash at all., " ESTRO / EAU / EORTC Recommendation on permanent seed implantation for Iocalised prostate cancer" (5) R. Nath et all., "Dosimetry of intersticial brachytherapy sources: Recommendations of the AAPM - TG 43", Med. Phys, 22 (2), pp. 209-234, 1995. (6) M. J. Rivard et all., "Update of AAPM TG 43: A revised AAPM protocol for brachytherapy dose calculations", Med. Phys, 31 (3), pp. 633-674, 2004. (7) J. Willins et all., "CT-based dosimetry for transperineal 1125 prostate brachytherapy" Int. J. Rad. Onc. Biol. Phys., 39, 347-353, 1997. 294 I n i t i a l e x p e r i e n c e w i t h t h e n e w Nucletron flexible applicator for HDR B r a c h y t h e r a p y in t h e t r e a t m e n t of e a r l y rectal cancer
A, Scott I, C. Lee 1, A. Myint 2 IClatterbridge Centre for Oncology, Physics Department, Wirral, UK 2Clatterbridge Centre for Oncology, Wirral, UK Background: Clatterbridge Centre for Oncology (CCO) has considerable experience of using radical radiotherapy for early rectal cancer as a conservative treatment alternative to surgery. The technique uses 20 fractions of 2.25Gy (45Gy total) of External Beam radiotherapy followed by an HDR brachytherapy boost (6-10Gy/1-2#). Several shortcomings of the NOVISAD applicator were identified including its relatively short length, bowing of the catheters when inflated, and patient discomfort due to its rigidity and diameter. CCO worked with Nucletron to design an improved applicator. M a t e r i a l s and Method: The new Flexible rectal applicator is made of a semi-rigid plastic and has a uniform diameter of 20mm. The eight catheters run in parallel along the whole length of the applicator. Combined with the reduced catheter separation (5 vs. 10.4mm for the NOVISAD), this leads to a more uniform dose distribution and the possibility of more accurate dose shaping. The treatment length of the new
R. Pirraco~ A. Pereira Instituto Portugu#s de Oncologia Francisco Gentil, Medical Physics, Porto, Portugal I n t r o d u c t i o n : The evaluation of the quality indices is the best way (1'2) to provide detailed information about the adequate close coverage and a good uniformity with a minimum overdosage in 12sI permanent prostate brachytherapy implants. The objective of this study is to analyse the quality indices of implants in our institution treated with this technique since June of 2004. Methods and Material: Our method follow the recommendations of several organizations, such as ABS (1,2), AAPM (3) and ESTRO(4), and we use the AAPM TG 43 (5,6) formalism for dosimetry. The prescrived dose is 145 Gy. We make real-time intra-operative dosimetry with TRUS (transrectal ultrasound video acquisition), and Varian Variseed 7.1 dosimetry software. The sources are IsoSeed I25.S06 12sI from Bebig and we mix loose and strands implant seed technique. A X-ray image was taken the day after aplication for seeds count. A C T was performed four weeks after the implant for pos-implant dosimetric analysis and seeds count. Intra-operative and pos-implant dosimetry are assured by Dose Volume Histogram (DVH) analises, where we take several indices, such as Vl00, V150, V200 (the percentage of prostate volume receiving 100%, 150% and 200% of the prescibed dose), D90 (dose to 90% of the prostate volume), Duretra (urethra maximum dose), D10rectum (dose to 10% of rectum volume), and V80 (the percentage of prostate volume receiving 80% of the prescibed dose, in the pos-implant analise) (7). Results: Next tables shows the quality indices obtained in 28 patients, the first table refering to the day of the implant and the second table to the pos-implants values.
$137
Min Med Max
INTRA-IMPLANT Vol. N°. N°. Total Activity V100 V150 V200 D90 Durete~ D10Recum (crn 3) seeds needles Activity /seed (%) ( % ) (%) (Gy) (Gy) (Gy) (mCi) (mCi) 19.0 35 15 17.5 0.391 95.9 45.0 16.7 160.0 168.0 82.0 35.2 57.6 22.8 26.5 0.459 97.8 56.0 24.0 169.7 192.3 101.2 65.7 82 30 40.3 0.542 99.9 72.0 40.2 187.0 223.0 133.0
POS - I M P L A N T
Min Med Max
Vol. (cm 3) 19.8 38.4 65.4
V100 (°/o) 73.6 84.7 91.9
V150 (%) 32.2 50.2 66
V200 (%) 17.4 26.2 40.8
V80
(%)
90.6 103.0 123.9
D90 (Gy) 83.3 128.3 151
D10Re~um (Gy) 60.1 90.7 151.6
Conclusion: All values show that we have good target coverage, with acceptable doses to adjacent normal structures, and these results are reforced with the posimplant dosimetry analysis. This results show that we are in the good way, but however, we have to increase the number and wait for patients follow up, but primary results 3 months after implants show a normal PSA values for all patients. References: (1) Subir Nag et all, "ABS Recommendations for transperineal permanent brachytherapy of prostate cancer", Int. J. Rad. Biol. Phys, Vol. 44, No 4, pp. 789-799, 1999. (2) Subir Nag et all, "The ABS Recommendations for permanent prostate brachytherapy posimplant dosimetric analysis", Int. J. Rad. Biol. Phys, Vol. 46, No 1, pp. 221-230, 2000. (3) Yan Yu et all., "Permanent prostate seed implant brachytherapy: report of the AAPM - TG 64", Med. Phys, 26 (10), pp. 2054-2076, 1999. (4) D. Ash at all., " ESTRO / EAU / EORTC Recommendation on permanent seed implantation for Iocalised prostate cancer" (5) R. Nath et all., "Dosimetry of intersticial brachytherapy sources: Recommendations of the AAPM - TG 43", Med. Phys, 22 (2), pp. 209-234, 1995. (6) M. J. Rivard et all., "Update of AAPM TG 43: A revised AAPM protocol for brachytherapy dose calculations", Med. Phys, 31 (3), pp. 633-674, 2004. (7) J. Willins et all., "CT-based dosimetry for transperineal 1125 prostate brachytherapy" Int. J. Rad. Onc. Biol. Phys., 39, 347-353, 1997. 294 I n i t i a l e x p e r i e n c e w i t h t h e n e w Nucletron flexible applicator for HDR B r a c h y t h e r a p y in t h e t r e a t m e n t of e a r l y rectal cancer
A, Scott I, C. Lee 1, A. Myint 2 IClatterbridge Centre for Oncology, Physics Department, Wirral, UK 2Clatterbridge Centre for Oncology, Wirral, UK Background: Clatterbridge Centre for Oncology (CCO) has considerable experience of using radical radiotherapy for early rectal cancer as a conservative treatment alternative to surgery. The technique uses 20 fractions of 2.25Gy (45Gy total) of External Beam radiotherapy followed by an HDR brachytherapy boost (6-10Gy/1-2#). Several shortcomings of the NOVISAD applicator were identified including its relatively short length, bowing of the catheters when inflated, and patient discomfort due to its rigidity and diameter. CCO worked with Nucletron to design an improved applicator. M a t e r i a l s and Method: The new Flexible rectal applicator is made of a semi-rigid plastic and has a uniform diameter of 20mm. The eight catheters run in parallel along the whole length of the applicator. Combined with the reduced catheter separation (5 vs. 10.4mm for the NOVISAD), this leads to a more uniform dose distribution and the possibility of more accurate dose shaping. The treatment length of the new