Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2017 May;18(3):37-43.
doi: 10.1002/acm2.12063. Epub 2017 Apr 13.

Dosimetric impacts of endorectal balloon in CyberKnife stereotactic body radiation therapy (SBRT) for early-stage prostate cancer

Hong F Xiang  1   2 , Hsiao-Ming Lu  2 , Jason A Efstathiou  2 , Anthony L Zietman  2 , Ricardo De Armas  3 , Kathryn Harris  3 , B Nicolas Bloch  1 , Muhammad Mustafa Qureshi  1 , Sean Keohan  1 , Ariel E Hirsch  1   2
Affiliations

Dosimetric impacts of endorectal balloon in CyberKnife stereotactic body radiation therapy (SBRT) for early-stage prostate cancer

Hong F Xiang et al. J Appl Clin Med Phys. 2017 May.

Abstract

Purpose: In SBRT for prostate cancer, higher fractional dose to the rectum is a major toxicity concern due to using smaller PTV margin and hypofractionation. We investigate the dosimetric impact on rectum using endorectal balloon (ERB) in prostate SBRT.

Materials and methods: Twenty prostate cancer patients were included in a retrospective study, ten with ERB and 10 without ERB. Optimized SBRT plans were generated on CyberKnife MultiPlan for 5 × 7.25 Gy to PTV under RTOG-0938 protocol for early-stage prostate cancer. For the rectum and the anterior half rectum, mean dose and percentage of volumes receiving 50%, 80%, 90%, and 100% prescription dose were compared.

Results: Using ERB, mean dose to the rectum was 62 cGy (P = 0.001) lower per fraction, and 50 cGy (P = 0.024) lower per fraction for the anterior half rectum. The average V50% , V80% , V90% , and V100% were lower by 9.9% (P = 0.001), 5.3% (P = 0.0002), 3.4% (P = 0.0002), and 1.2% (P = 0.005) for the rectum, and lower by 10.4% (P = 0.009), 8.3% (P = 0.0004), 5.4% (P = 0.0003), and 2.1% (P = 0.003) for the anterior half rectum.

Conclusions: Significant reductions of dose to the rectum using ERB were observed. This may lead to improvement of the rectal toxicity profiles in prostate SBRT.

Keywords: SBRT; CyberKnife; endorectal balloon; prostate cancer; rectum toxicity.

PubMed Disclaimer

Figures

Figure 1
Figure 1
The endorectal balloon (ERB) used for patients included in this planning study.
Figure 2
Figure 2
Typical dose distributions of CyberKnife prostate SBRT plans for a case from the ERB group (left) and a case from the noERB group (right). The top row for axial view, bottom row for sagittal view. The anterior half of the rectum contours were obtained by bisecting the full rectum contours from the midline slice‐by‐slice.
Figure 3
Figure 3
DVHs for a typical case in the ERB group (a) and in the noERB group (b).
Figure 4
Figure 4
DVHs profiles for the rectum volume (left) and anterior half rectum volume (right) in the intermediate‐to‐high dose region 50%–100% of prescription dose 36.25 Gy.
See this image and copyright information in PMC

References

    1. Brenner DJ, Hall EJ. Fractionation and protraction for radiotherapy of prostate carcinoma. Int J Radiat Oncol Biol Phys. 1999;43:1095–1101. - PubMed
    1. Fowler JF. The radiobiology of prostate cancer including new aspects of fractionated radiotherapy. Acta Oncol. 2005;44:265–276. - PubMed
    1. Miralbell R, Roberts SA, Zubizarreta E, Hendry JH. Dose‐fractionation sensitivity of prostate cancer deduced from radiotherapy outcomes of 5,969 patients in seven international institutional datasets: Alpha/beta = 1.4 (0.9–2.2) Gy. Int J Radiat Oncol Biol Phys. 2012;82:e17–e24. - PubMed
    1. Xie Y, Djajaputra D, King CR, Hossain S, Ma L, Xing L. Intrafractional motion of the prostate during hypofractionated radiotherapy. Int J Radiat Oncol Biol Phys. 2008; 72:236–246. - PMC - PubMed
    1. Langen KM, Willoughby TR, Meeks SL, et al. Observations on real‐time prostate gland motion using electromagnetic tracking. Int J Radiat Oncol Biol Phys. 2008;71:1084–1090. - PubMed

LinkOut - more resources