Assessment of PTV Margins Accounting for Prostate Intrafraction Motion in SBRT with Online IGRT

Magli A, Urpis M, Crespi M, Guernieri M, Titone F, Moretti E and Foti C

Department of Radiation Oncology, University Hospital Udine, Italy
Department of Medical Physics, University Hospital Udine, Italy

^*Correspondance to: Magli A 

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Abstract:

Purpose: The aim of this work was to assess PTV margins suitable for SBRT of prostate cancer uncertainties after daily online correction. Moreover, intra-fraction prostate motion is analyzed with the aim to identify its main causesMaterial and
Methods: Between 2013 and 2014, 43 patients with low or intermediate risk prostate cancer were treated with 7-fraction SBRT in supine position, with implanted Fiducial Markers (FM), empty rectum and full bladder. The van Herk’s formula was applied to calculate the PTV margins of prostate/seminal vescicles. To investigate the causes of organ motion, the bladder volume and the rectum wall distension and the treatment time.Results: systematic increase of bladder and the rectal distension not influence the prostate displacement (p = 0.55 and p = 0.32 respectively). Significant correlation was observed between the intrafraction composite shift of the prostate volume and the elapsed treatment time (p = 0.036).
Conclusion: our data suggest a good control of intrafraction motion. The prostate intrafraction motion is shown to be dependent on elapsed treatment time.

Keywords:

Prostate cancer; IGRT; Organ motion

Cite the Article:

Magli A, Urpis M, Crespi M, Guernieri M, Titone F, Moretti E, et al. Assessment of PTV Margins Accounting for Prostate Intrafraction Motion in SBRT with Online IGRT. Clin Oncol. 2017; 2: 1275.