A dosimetric dnalysis of flattening-filter-free mode linear accelerator-based stereotactic body radiation therapy and HDR brachytherapy for prostate cancer

Andrew Thomas Wong, Tejas Telivala, Matthew Worth, David Schwartz, David Schreiber


Purpose: Prior studies have reported that linear accelerator (LINAC)-based stereotactic body radiation therapy (SBRT) plans for prostate cancer are unable to achieve comparable intraprostatic doses to high-dose-rate brachytherapy (HDR).  However, the utilization of flattening-filter-free (FFF) beams provides superior dose distributions compared with flattened beams. The purpose of this study was to test the feasibility of achieving the high intraprostatic doses observed in HDR by utilizing LINAC - based SBRT with FFF beams.

Methods: We randomly selected 10 patients with localized prostate cancer previously treated at our institution in 2013. FFF-mode LINAC-based SBRT and simulated HDR (using virtual HDR catheters) plans were generated for each patient. The planning target volume (PTV) V100, V125, V150 and V200 values were compared between the two plans using the two-sided paired samples t-test.

Results: Regarding the PTV coverage, the mean V100 was slightly higher for SBRT at 96.47% compared with 94.68% for HDR (p = 0.003). The V125 (61.69% versus 66.51%, p = 0.004) and V200 (15.06% versus 19.66%, p < 0.001) were slightly lower for SBRT. There were no significant differences in V150 between the two plans (47.59% versus 49.8%, p = 0.375). Rectal and bladder dosimetry were also comparable between the two modalities, though the rectal maximum dose was lower in the SBRT plan (99.6% versus 103.66%, p = 0.006) and the dose to 15cc of bladder was lower in the HDR plan (96.34% versus 78.18%, p = 0.005).

Conclusion: Utilization of FFF mode LINAC-based SBRT allows for achievable dosimetry that is very similar to high dose rate brachytherapy. Further studies are warranted regarding the safety and efficacy of this modality. 


Prostate cancer, High-dose rate brachytherapy, Stereotactic body radiation therapy, Dosimetry, Flattening filter-free

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Brenner DJ, Hall EJ. Fractionation and protraction for radiotherapy of prostate carcinoma. Int J Radiat Oncol Biol Phys. 1999;43:1095-101.

Fowler J, Chappell R, Ritter M. Is alpha/beta for prostate tumors really low? Int J Radiat Oncol Biol Phys. 2001;50:1021-31.

Brenner DJ, Martinez AA, Edmundson GK, et al. Direct evidence that prostate tumors show high sensitivity to fractionation (low alpha/beta ratio), similar to late-responding normal tissue. Int J Radiat Oncol Biol Phys. 2002;52:6-13.

Yoshioka Y, Nose T, Yoshida K, et al. High-dose-rate interstitial brachytherapy as a monotherapy for localized prostate cancer: Treatment description and preliminary results of a phase I/II clinical trial. Int J Radiat Oncol Biol Phys. 2000;48:675-681.

Martinez AA, Pataki I, Edmundson G, et al. Phase II prospective study of the use of conformal high-dose-rate brachytherapy as monotherapy for the treatment of favorable stage prostate cancer: A feasibility report. Int J Radiat Oncol Biol Phys. 2001;49:61-9.

Corner C, Rojas AM, Bryant L, et al. A Phase II study of high-dose rate afterloading brachytherapy as monotherapy for the treatment of localized prostate cancer. Int J Radiat Oncol Biol Phys. 2008;72:441-6.

Demanes DJ, Martinez AA, Ghilezan M, et al. High-dose-rate monotherapy: Safe and effective brachytherapy for patients with localized prostate cancer. Int J Radiat Oncol Biol Phys. 2011;81:1286-92.

Hsu IC, Yamada Y, Merrick G, et al. ACR Appropriateness Criteria High-dose-rate brachytherapy for prostate cancer. American College of Radiology. Retrieved May 25, 2015, from https://acsearch.acr.org/docs/3082863/Narrative/.

King CR, Brooks JD, Gill H, et al. Long-term outcomes from a prospective trial of stereotactic body radiotherapy for low-risk prostate cancer. Int J Radiat Oncol Biol Phys. 2012;82:877–82.

McBride SM, Wong DS, Dombrowski JJ, et al. Hypofractionated stereotactic body radiotherapy in low-risk prostate adenocarcinoma: preliminary results of a multi-institutional phase 1 feasibility trial. Cancer. 2012;118:3681-90.

Bolzicco G, Favretto MS, Scremin E, et al. Image-guided stereotactic body radiation therapy for clinically localized prostate cancer: preliminary clinical results. Technol Cancer Res Treat. 2010;9:473–7.

Boike TP, Lotan Y, Cho LC, et al. Phase I dose-escalation study of stereotactic body radiation therapy for low- and intermediate-risk prostate cancer. J Clin Oncol. 2011;29:2020–6.

Katz AJ, Santoro M, Diblasio F, et al. Stereotactic body radiotherapy for localized prostate cancer: disease control and quality of life after 6 years. Radiat Oncol. 2013;8(1):118.

Jabbari S, Weinberg VK, Kaprealian T, et al. Stereotactic body radiotherapy as monotherapy or post external beam radiotherapy boost for prostate cancer: technique, early toxicity, and PSA response. Int J Radiat Oncol Biol Phys. 2012;82:228-34.

Fuller DB, Naitoh J, Lee C, et al. Virtual HDR CyberKnife treatment for localized prostatic carcinoma: dosimetry comparison with HDR brachytherapy and preliminary clinical observations. Int J Radiat Oncol Biol Phys. 2008;70:1588–97.

Fukuda S, Seo Y, Shiomi H, et al. Dosimetry analyses comparing high-dose-rate brachytherapy, administered as monotherapy for localized prostate cancer, with stereotactic body radiation therapy simulated using Cyberknife. J Radiat Res. 2014;55:1114-21.

Spratt DE, Scala LM, Folkert M, et al. A comparative dosimetric analysis of virtual stereotactic body radiotherapy to high dose rate monotherapy for intermediate risk prostate cancer. Brachytherapy. 2013;12:428-33.

Thomas EM, Popple RA, Prendergast BM, et al. Effects of flattening filter-free and volumetric modulated arc therapy delivery on treatment efficiency. J Appl Clin Med Phys. 2013;14:4328.

Hrbacek J, Lang S, Graydon SN, et al. Dosimetric comparison of flattened and unflattened beams for stereotactic ablative radiotherapy of stage I non-small cell lung cancer. Med Phys. 2014;41:031709.

Navarria P, Ascolese AM, Mancosu P, et al. Volumetric modulated arc therapy with flattening filter free (FFF) beams for stereotactic body radiation therapy (SBRT) in patients with medically inoperable early stage non-small cell lung cancer (NSCLC). Radiother Oncol. 2013;107:414-8.

Macdougall ND, Dean C, Muirhead R. Stereotactic body radiotherapy in prostate cancer: is rapidarc a better solution than cyberknife? Clin Oncol. 2014;26:4-9.

Pawlicki T, Kim GY, Hsu A, et al. Investigation of linac-based image-guided hypofractionated prostate radiotherapy. Med Dosim. 2007;32:71-9.

Fuller DB, Naitoh J, Mardirossian G. Virtual HDR Cyberknife SBRT for localized prostatic carcinoma: 5-year disease-free survival and toxicity observations. Front Oncol. 2014;4:321.

Pontoriero A, Iati G, Mondello S, et al. High-dose robotic stereotactic body radiotherapy in the treatment of patients with prostate cancer: preliminary results in 26 patients. Technol Cancer Res Treat. 2016;15:179-85.

Zietman AL, Bae K, Slater JD, et al. Randomized trial comparing conventional-dose with high-dose conformal radiation therapy in early-stage adenocarcinoma of the prostate: long-term results from proton radiation oncology group/american college of radiology 95-09. J Clin Oncol. 2010;28:1106-11.

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;70:67-74.

Stone NN, Potters L, Davis BJ, et al. Multicenter analysis of effect of high biologic effective dose on biochemical failure and survival outcomes in patients with Gleason 7-10 prostate cancer treated with permanent prostate brachytherapy. Int J Radiat Oncol Biol Phys. 2009;73:341-6.

Elsayed H, Bolling T, Moustakis C, et al. Organ movements and dose exposures in teletherapy of prostate cancer using a rectal balloon. Strahlenther Onkol. 2007;183:617-24.

DOI: http://dx.doi.org/10.14319/ijcto.44.4

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