Variations of tumor control and rectum complication probabilities due to random set-up errors during conformal radiation therapy of prostate cancer.

BACKGROUND AND PURPOSE The effect of random set-up errors on tumor control probability (TCP) and rectum complication probability (NTCP) on 3D conformal treatment planning of prostate cancer has been investigated by applying the convolution method originally proposed by Leong (Leong, J. Implementation of random positioning error in computerized radiation treatment planning systems as a result of fractionation. Phys. Med. Biol. 32: 327-334, 1987). MATERIALS AND METHODS The combined influence of the standard deviation of the random shifts probability distribution (sigma) of the dose and of the Beam's-eye-view margin (M) between the clinical target volume (CTV) and the edge of the blocks have been investigated in two patients. RESULTS AND CONCLUSIONS Random set-up error has been found to decrease TCP (for a typical 70 Gy CTV mean dose) by up to 6% for a 1 cm margin (sigma = 7 mm). When M is equal to or larger than 1.5 cm, no relevant effects on TCP are obtained. Maximum acceptable TCP values (corresponding to a rectum NTCP equal to 5%) have been derived and the dependence on sigma and M has been investigated.

[1]  D Yan,et al.  A new model for "accept or reject" strategies in off-line and on-line megavoltage treatment evaluation. , 1995, International journal of radiation oncology, biology, physics.

[2]  M. Goitein,et al.  Tolerance of normal tissue to therapeutic irradiation. , 1991, International journal of radiation oncology, biology, physics.

[3]  A Bel,et al.  High-precision prostate cancer irradiation by clinical application of an offline patient setup verification procedure, using portal imaging. , 1996, International journal of radiation oncology, biology, physics.

[4]  G J Kutcher,et al.  The effect of setup uncertainties on the treatment of nasopharynx cancer. , 1993, International journal of radiation oncology, biology, physics.

[5]  Icru.  Prescribing, recording, and reporting photon beam therapy , 1993 .

[6]  M van Herk,et al.  Target margins for random geometrical treatment uncertainties in conformal radiotherapy. , 1996, Medical physics.

[7]  M. Goitein,et al.  Fitting of normal tissue tolerance data to an analytic function. , 1991, International journal of radiation oncology, biology, physics.

[8]  G. Storme,et al.  Routine clinical use of on-line portal imaging (OPI) using siemens beamview , 1991 .

[9]  A Fenster,et al.  Daily monitoring and correction of radiation field placement using a video-based portal imaging system: a pilot study. , 1992, International journal of radiation oncology, biology, physics.

[10]  J W Denham,et al.  Objective decision-making following a portal film: the results of a pilot study. , 1993, International journal of radiation oncology, biology, physics.

[11]  J Bijhold,et al.  Maximizing setup accuracy using portal images as applied to a conformal boost technique for prostatic cancer. , 1992, Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology.

[12]  A. Brahme,et al.  Optimal radiation beam profiles considering uncertainties in beam patient alignment. , 1993, Acta oncologica.

[13]  R Mohan,et al.  The role of uncertainty analysis in treatment planning. , 1991, International journal of radiation oncology, biology, physics.

[14]  S Webb,et al.  A model for calculating tumour control probability in radiotherapy including the effects of inhomogeneous distributions of dose and clonogenic cell density. , 1993, Physics in medicine and biology.

[15]  J. Lebesque.  Incorporation of geometrical uncertainties into 3D treatment planning of prostate cancer , 1995 .

[16]  M Coghe,et al.  Routine clinical on-line portal imaging followed by immediate field adjustment using a tele-controlled patient couch. , 1992, Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology.

[17]  A G Visser,et al.  A quality control study of the accuracy of patient positioning in irradiation of pelvic fields. , 1996, International Journal of Radiation Oncology, Biology, Physics.

[18]  S. Webb,et al.  A comparison of proton and megavoltage X-ray treatment planning for prostate cancer. , 1994, Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology.

[19]  A B Wolbarst,et al.  Optimization of radiation therapy, III: A method of assessing complication probabilities from dose-volume histograms. , 1987, International journal of radiation oncology, biology, physics.

[20]  J. Leong,et al.  Implementation of random positioning error in computerised radiation treatment planning systems as a result of fractionation. , 1987, Physics in medicine and biology.

[21]  C. Burman,et al.  Calculation of complication probability factors for non-uniform normal tissue irradiation: the effective volume method. , 1989, International journal of radiation oncology, biology, physics.

[22]  P. Storchi,et al.  Calculation of the absorbed dose distribution due to irregularly shaped photon beams using pencil beam kernels derived form basic beam data. , 1996, Physics in medicine and biology.

[23]  T LoSasso,et al.  The use of a multi-leaf collimator for conformal radiotherapy of carcinomas of the prostate and nasopharynx. , 1993, International journal of radiation oncology, biology, physics.

[24]  M van Herk,et al.  Quantification of organ motion during conformal radiotherapy of the prostate by three dimensional image registration. , 1995, International journal of radiation oncology, biology, physics.

[25]  M Goitein,et al.  Causes and consequences of inhomogeneous dose distributions in radiation therapy. , 1986, International journal of radiation oncology, biology, physics.

[26]  M Wannenmacher,et al.  Influence of the positioning error on 3D conformal dose distributions during fractionated radiotherapy. , 1994, Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology.