Adaptive IG-IMRT for Prostate Cancer
Authors:
J. Vaňásek 1; K. Odrážka 1,2,3; M. Doležel 1,3; I. Kolářová 1
Authors‘ workplace:
Oddělení klinické a radiační onkologie, Multiscan s. r. o., Pardubická krajská nemocnice a. s., Pardubice
1; 1. a 3. lékařská fakulta, Univerzita Karlova v Praze
2; Katedra radiační onkologie IPVZ, Praha
3
Published in:
Klin Onkol 2011; 24(5): 361-366
Category:
Original Articles
Overview
Backgrounds:
Adaptive image-guided intensity-modulated radiation therapy (IG-IMRT) is a perspective method for the treatment of localized prostate cancer. Validate optimal protocols for IG-IMRT using kilovoltage cone-beam CT (CBCT) are required.
Patients and Methods:
Seventy-six patients with prostate cancer were treated using adaptive IG-IMRT. Based on the CBCT performed during the first 10 fractions of radiotherapy, an average prostate position in relation to the pelvic bones was determined in antero-posterior AP, supero-inferior SI, and right-left axes. An adapted treatment plan for the second phase of the treatment included an isocenter shift into its average position (correction of the systematic error Σ). A margin between a clinical and planned target volume (CTV-PTV) was adjusted according to the magnitude of random error σ. During the second phase of radiotherapy, set-up of patients was performed daily on pelvic bones using kilovoltage skiagraphic imaging in two projections (kV-kV). Follow-up CBCTs were repeated once a week.
Results:
An average isocenter position differed from the position of a reference planning CT isocenter in at least one axis in 63 patients (83%). Major changes were recorded in AP axis – shift ≥ 2 mm in 33 patients (43%), shift ≥ 5 mm in 7 patients (9%). PTV for the second phase of radiotherapy was in the range of 6–10 mm in AP axis, 6–8 mm in SI axis, and 6 mm in RL axis. Mean σ value in the AP axis was smaller in patients with a specific diet compared to patients without the diet (2.2 mm vs. 2.7 mm, p = 0.05). We evaluated 446 follow-up CBCT images from the second phase of radiotherapy (66 patients had 6 CBCT, 10 patients had 5 CBCT). Set-up error exceeding CTV-PTV margin occurred in 4 cases with no more than once per patient. Safety margin was sufficient in 72/76 patients (95%).
Conclusion:
IG-IMRT protocol integrating CBCT and kV-kV imaging provided adequate coverage of the target volume and proved to be compatible with departmental workflow. Margin reduction around the CTV is a prerequisite for dose escalation aimed at a intraprostatic lesion.
Key words:
prostate cancer – radiation therapy – adaptive – image guidance – IMRT
The authors declare they have no potential conflicts of interest concerning drugs, products, or services used in the study.
The Editorial Board declares that the manuscript met the ICMJE “uniform requirements” for biomedical papers.
Submitted:
16. 2. 2011
Accepted:
15. 3. 2011
Sources
1. Dearnaley DP, Sydes MR, Graham JD et al. Escalated-dose versus standard-dose conformal radiotherapy in prostate cancer: first results from the MRC RT01 randomised controlled trial. Lancet Oncol 2007; 8(6): 475–487.
2. Kuban DA, Tucker SL, Dong L et al. Long-term results of the M. D. Anderson randomized dose-escalation trial for prostate cancer. Int J Radiat Oncol Biol Phys 2008; 70(1): 67–74.
3. Dolezel M, Odrazka K, Vaculikova M et al. Dose escalation in prostate radiotherapy up to 82 Gy using simultaneous integrated boost: direct comparison of acute and late toxicity with 3D-CRT 74 Gy and IMRT 78 Gy. Strahlenther Onkol 2010; 186(4): 197–202.
4. Verellen D, De Ridder M, Storme G. A (short) history of image-guided radiotherapy. Radiother Oncol 2008; 86(1): 4–13.
5. Xing L, Thorndyke B, Schreibmann E et al. Overview of image-guided radiation therapy. Med Dosim 2006; 31(2): 91–112.
6. Ghilezan M, Yan D, Martinez A. Adaptive radiation therapy for prostate cancer. Semin Radiat Oncol 2010; 20(2): 130–137.
7. Yan D, Vicini F, Wong J et al. Adaptive radiation therapy. Phys Med Biol 1997; 42(1): 123–132.
8. Martinez A, Yan D, Lockman D et al. Improvement in dose escalation using the process of adaptive radiotherapy combined with three-dimensional conformal or intensity-modulated beams for prostate cancer. Int J Radiat Oncol Biol Phys 2001; 50(5): 1226–1234.
9. Nijkamp J, Pos FJ, Nuver TT et al. Adaptive radiotherapy for prostate cancer using kilovoltage cone-beam computed tomography: first clinical results. Int J Radiat Oncol Biol Phys 2008; 70(1): 75–82.
10. Van Herk M, Remeijer P, Rasch C et al. The probability of correct target dosage: dose-population histograms for deriving treatment margins in radiotherapy. Int J Radiat Oncol Biol Phys 2000; 47(4): 1121–1135.
11. Odrážka K, Vaculíková M, Petera J et al. Nepřesnost nastavení během konformní radioterapie karcinomu prostaty. Radiační onkologie 2011; 1: 11–19.
12. Tanyi JA, He T, Summers PA et al. Assessment of planning target volume margins for intensity-modulated radiotherapy of the prostate gland: role of daily inter- and intrafraction motion. Int J Radiat Oncol Biol Phys 2010; 78(5): 1579–1585.
13. Schallenkamp JM, Herman MG, Kruse JJ et al. Prostate position relative to pelvic bony anatomy based on intraprostatic gold markers and electronic portal imaging. Int J Radiat Oncol Biol Phys 2005; 63(3): 800–811.
14. Bortfeld T, van Herk M, Jiang SB. When should systematic patient positioning errors in radiotherapy be corrected. Phys Med Biol 2002; 47(23): N297–N302.
15. Litzenberg DW, Balter JM, Lam KL et al. Retrospective analysis of prostate cancer patients with implanted gold markers using off-line and adaptive therapy protocols. Int J Radiat Oncol Biol Phys 2005; 63(1): 123–133.
16. White EA, Brock KK, Jaffray DA et al. Inter-observer variability of prostate delineation on cone beam computerized tomography images. Clin Oncol 2009; 21(1): 32–38.
17. Polat B, Guenther I, Wilbert J et al. Intra-fractional uncertainties in image-guided intensity-modulated radiotherapy (IMRT) of prostate cancer. Strahlenther Onkol 2008; 184: 668–673.
18. de Crevoisier R, Tucker SL, Dong L et al. Increased risk of biochemical and local failure in patients with distended rectum on the planning CT for prostate cancer radiotherapy. Int J Radiat Oncol Biol Phys 2005; 62(4): 965–973.
19. Engels B, Soete G, Verellen D et al. Conformal arc radiotherapy for prostate cancer: increased biochemical failure in patients with distended rectum on the planning computed tomogram despite image guidance by implanted markers. Int J Radiat Oncol Biol Phys 2008; 74(2): 388–391.
20. Smitsmans MH, Pos FJ, de Bois J et al. The influence of a dietary protocol on cone beam CT-guided radiotherapy for prostate cancer patients. Int J Radiat Oncol Biol Phys 2008; 71(4): 1279–1286.
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