Evaluación de Errores de Posicionamiento en los 6 Grados de Libertad en Pacientes con Cáncer de próstata tratados con radioterapia

Resumen

Objetivos Determinar la magnitud de los errores de posicionamiento en los 6 grados de libertad y calcular el Margen a CTV para un protocolo adaptado en pacientes con cáncer de próstata temprano y localmente avanzado en un centro de referencia en Colombia.

Métodos Se realizó un estudio observacional prospectivo en 61 pacientes con cáncer de próstata tratados con radioterapia en el Centro Javeriano de Oncología del Hospital Universitario San Ignacio durante el 2018, con toma de imágenes volumétricas de rayos x durante los primeros 3 días de tratamiento obteniéndose un promedio en errores traslacionales y rotacionales. Posteriormente se tomaron imágenes semanales. Además, se realizó el cálculo del margen al PTV y variaciones en vejiga y recto durante el tratamiento.

Resultados Un total de 508 imágenes fueron registradas durante las 8 semanas de tratamiento, los errores traslacionales y rotacionales tuvieron un comportamiento alrededor de cero sin diferencias significativas inclusive en pacientes con IMC > = 25. También se calculó el margen al PTV encontrándose entre 5 y 8 mm, en cuanto a las medidas de vejiga y recto no se encontraron diferencias estadísticamente significativas en las imágenes adquiridas durante la radioterapia.

Conclusiones De acuerdo a los datos encontrados en este estudio, una adecuada reproducibilidad en paciente con cáncer de próstata puede ser encontrada usando el método de registro rígido de la anatomía pélvica ósea, promediando las 3 primeras imágenes y posteriormente con imágenes semanales, en centros con alta demanda de pacientes garantizando así una adecuada precisión del tratamiento.

Abstract

Objectives To determine the magnitude of the positioning errors in the 6 degrees of freedom and calculate the Margin to CTV for an adapted protocol in patients with early and locally advanced prostate cancer in a reference center in Colombia.

Methods A prospective observational study was performed in 61 prostate cancer patients treated with radiotherapy at the Javeriano Oncology Center of the San Ignacio University Hospital during 2018, with volumetric X-ray imaging during the first 3 days of treatment obtaining a average in translational and rotational errors. Subsequently, weekly images were taken. In addition, the calculation of the margin to the PTV and variations in bladder and rectum during the treatment was performed.

Results A total of 508 images were recorded during the 8 weeks of treatment, translational and rotational errors had a behavior around zero without significant differences even in patients with BMI > = 25. The margin to the PTV was also calculated between 5 and 8 mm, in terms of bladder and rectum measurements, no statistically significant differences were found in the images acquired during radiotherapy.

Conclusions According to the data found in this study, an adequate reproducibility in a patient with prostate cancer can be found using the method of rigid registration of the pelvic bone anatomy, averaging the first 3 images and subsequently with weekly images, in centers with high patient demand guaranteeing adequate treatment accuracy.

Palabras clave

radioterapia - cáncer de próstata - error de posicionamiento - márgenes

Keywords

radiation therapy - prostate cáncer - positioning error - margins

Publication History

Received: 21 January 2020

Accepted: 17 June 2020

Article published online:
13 January 2021

• Referencias

• 1 Bray F, Ferlay J, Soerjomataram I, Siegel RL, Torre LA, Jemal A. Global cancer statistics 2018: GLOBOCAN estimates of incidence and mortality worldwide for 36 cancers in 185 countries. CA Cancer J Clin 2018; 68 (06) 394-424
• 2 Holmberg L, Bill-Axelson A, Helgesen F. et al; Scandinavian Prostatic Cancer Group Study Number 4. A randomized trial comparing radical prostatectomy with watchful waiting in early prostate cancer. N Engl J Med 2002; 347 (11) 781-789
• 3 Bill-Axelson A, Holmberg L, Garmo H. et al. Radical prostatectomy or watchful waiting in early prostate cancer. N Engl J Med 2014; 370 (10) 932-942
• 4 Zelefsky MJ, Leibel SA, Gaudin PB. et al. Dose escalation with three-dimensional conformal radiation therapy affects the outcome in prostate cancer. Int J Radiat Oncol Biol Phys 1998; 41 (03) 491-500
• 5 Pollack A, Zagars GK, Starkschall G. et al. Prostate cancer radiation dose response: results of the M. D. Anderson phase III randomized trial. Int J Radiat Oncol Biol Phys 2002; 53 (05) 1097-1105
• 6 Pouliot J, Bani-Hashemi A, Chen J. et al. Low-dose megavoltage cone-beam CT for radiation therapy. Int J Radiat Oncol Biol Phys 2005; 61 (02) 552-560
• 7 Vences L, Wulf J, Vordermark D, Sauer O, Berlinger K, Roth M. Target motion measurement without implanted markers and its validation by comparison with manually obtained data. Med Phys 2005; 32 (11) 3431-3439
• 8 Ma CM, Paskalev K. In-room CT techniques for image-guided radiation therapy. Med Dosim 2006; 31 (01) 30-39
• 9 Létourneau D, Wong JW, Oldham M. et al. Cone-beam-CT guided radiation therapy: technical implementation. Radiother Oncol 2005; 75 (03) 279-286
• 10 Sánchez R, González A, Rocha A. Reproducibility of patient positioning in radiation therapy Centro Javeriano de Oncología. Universitas Medica 2011; 52 (01) 44-61
• 11 Bel A, Vos PH, Rodrigus PT. et al. High-precision prostate cancer irradiation by clinical application of an offline patient setup verification procedure, using portal imaging. Int J Radiat Oncol Biol Phys 1996; 35 (02) 321-332
• 12 Amer AM, Mackay RI, Roberts SA, Hendry JH, Williams PC. The required number of treatment imaging days for an effective off-line correction of systematic errors in conformal radiotherapy of prostate cancer--a radiobiological analysis. Radiother Oncol 2001; 61 (02) 143-150
• 13 Ost P, De Gersem W, De Potter B, Fonteyne V, De Neve W, De Meerleer G. A comparison of the acute toxicity profile between two-dimensional and three-dimensional image-guided radiotherapy for postoperative prostate cancer. Clin Oncol (R Coll Radiol) 2011; 23 (05) 344-349
• 14 Ung NM, Wee L, Hackett SL, Jones A, Lim TS, Harper CS. Comparison of low-dose, half-rotation, cone-beam CT with electronic portal imaging device for registration of fiducial markers during prostate radiotherapy. J Appl Clin Med Phys 2013; 14 (04) 4249
• 15 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 (04) 965-973
• 16 Frank SJ, Dong L, Kudchadker RJ. et al. Quantification of prostate and seminal vesicle interfraction variation during IMRT. Int J Radiat Oncol Biol Phys 2008; 71 (03) 813-820
• 17 van Herk M, Remeijer P, Rasch C, Lebesque JV. The probability of correct target dosage: dose-population histograms for deriving treatment margins in radiotherapy. Int J Radiat Oncol Biol Phys 2000; 47 (04) 1121-1135
• 18 Ten Haken RK, Forman JD, Heimburger DK. et al. Treatment planning issues related to prostate movement in response to differential filling of the rectum and bladder. Int J Radiat Oncol Biol Phys 1991; 20 (06) 1317-1324
• 19 Tehrani JN, O'Brien RT, Poulsen PR, Keall P. Real-time estimation of prostate tumor rotation and translation with a kV imaging system based on an iterative closest point algorithm. Phys Med Biol 2013; 58 (23) 8517-8533
• 20 Wong JR, Gao Z, Uematsu M. et al. Interfractional prostate shifts: review of 1870 computed tomography (CT) scans obtained during image-guided radiotherapy using CT-on-rails for the treatment of prostate cancer. Int J Radiat Oncol Biol Phys 2008; 72 (05) 1396-1401