Skip to main content Accessibility help

Dosimetric comparison of flattened and flattening filter-free beams for liver stereotactic body irradiation in deep inspiration breath hold, and free breathing conditions

  • N. Munirathinam (a1) and P. N. Pawaskar (a1)



The aim of this study is to evaluate the influence of flattened and flattening filter-free (FFF) beam 6 MV photon beam for liver stereotactic body radiation therapy by using volumetric modulated arc therapy (VMAT) technique in deep inspiration breath hold (DIBH) and free breathing condition.

Materials and methods

Eight liver metastasis patients (one to three metastasis lesions) were simulated in breath hold and free breathing condition. VMAT-based treatment plans were created for a prescription dose of 50 Gy in 10 fractions, using a 230° coplaner arc and 60° non-coplanar arc for both DIBH and free breathing study set. Treatment plans were evaluated for planning target volume (PTV) dose coverage, conformity and hot spots. Parallel and serial organs at risk were compared for average and maximum dose, respectively. Dose spillages were evaluated for different isodose volumes from 5 to 80%.


Mean D98% (dose received by 98% target volume) for FFF in DIBH, flattened beam in DIBH, FFF in free breathing and flatten beam in free breathing dataset were 48·9, 47·81, 48·5 and 48·3 Gy, respectively. D98% was not statistically different between FFF and flatten beam (p = 0·34 and 0·69 for DIBH and free breathing condition). PTV V105% (volume receiving 105% dose) for the same set were 3·76, 0·25, 1·2 and 0·4%, respectively. Mean heterogeneity index for all study sets and beam models varies between 1·05 and 1·07. Paddik conformity index using unflattened and flattened beam in DIBH at 98% prescription dose were 0·91 and 0·79, respectively. Maximum variation of isodose volume was observed for I-5%, which was ranging between 2288·8 and 2427·2 cm3. Increase in isodose value shows a diminishing difference in isodose volumes between different techniques. DIBH yields a significant reduction in the chest wall dose compared with free breathing condition. Average monitor units for FFF beam in DIBH, flattened beam in DIBH, FFF beam in free breathing CT dataset and flattened beam in free breathing CT dataset were 1318·6 ± 265·1, 1940·3 ± 287·6, 1343·3 ± 238·1 and 2192·5 ± 252·6 MU.


DIBH and FFF is a good combination to reduce the treatment time and to achieve better tumour conformity. No other dosimetric gain was observed for FFF in either DIBH or free breathing condition.


Corresponding author

Author for correspondence: N. Munirathinam, The Department of Medical Physics, Centre for Interdisciplinary Research, D.Y. Patil Education Society (Deemed to be) University, Kolhapur-416006, Maharashtra, India. Tel: +91-7709316668. Fax: 00231 260 1235. E-mail:


Hide All

Cite this article: Munirathinam N, Pawaskar PN. (2019) Dosimetric comparison of flattened and flattening filter-free beams for liver stereotactic body irradiation in deep inspiration breath hold, and free breathing conditions. Journal of Radiotherapy in Practice18: 169–174. doi: 10.1017/S146039691800064X



Hide All
1. Kry, S F, Howell, R M, Titt, U, Salehpour, M, Mohan, R, Vassiliev, O N. Energy spectra, sources, and shielding considerations for neutrons generated by a flattening filter-free Clinac. Med Phys 2008; 35: 19061911.
2. Vassiliev, O N, Kry, S F, Chang, J Y, Balter, P A, Titt, U, Mohan, R. Stereotactic radiotherapy for lung cancer using a flattening filter free Clinac. J Appl Clin Med Phys 2009; 10 (1): 1421.
3. Kry, S F, Howell, R M, Polf, J, Mohan, R, Vassiliev, O N. Treatment vault shielding for a flattening filter-free medical linear accelerator. Phys Med Biol 2009; 54: 12651273.
4. Kragl, G, Baier, F, Lutz, S et al. Flattening filter free beams in SBRT and IMRT: dosimetric assessment of peripheral doses. Z Med Phys 2011; 21: 91101.
5. Mancosu, P, Castiglioni, S, Reggiori, G et al. Stereotactic body radiation therapy for liver tumours using flattening filter free beam: dosimetric and technical considerations. Radiat Oncol 2012; 7 (1): 16.
6. Reggiori, G, Mancosu, P, Castiglioni, S et al. Can volumetric modulated arc therapy with flattening filter free beams play a role in stereotactic body radiotherapy for liver lesions? A volume-based analysis. Med Phys 2012; 39 (2): 11121118.
7. Nicolini, G, Ghosh-Laskar, S, Shrivastava, S K et al. Volumetric modulation arc radiotherapy with flattening filter-free beams compared with static gantry IMRT and 3D conformal radiotherapy for advanced esophageal cancer: a feasibility study. Int J Radiat Oncol Biol Phys 2012; 84: 553560.
8. Sarkar, B, Pradhan, A. Choice of appropriate beam model and gantry rotational angle for low-dose gradient-based craniospinal irradiation using volumetric-modulated arc therapy. J Radiother Pract 2017; 16 (1): 5364.
9. Navarria, P, Ascolese, A M, Mancosu, P et al. Volumetric modulated arc therapy with flattening filter free (3F) beams for stereotactic body radiation therapy (SBRT) in patients with medically inoperable early stage non-small cell lung cancer (NSCLC). Radiother Oncol 2013; 107: 414418.
10. Sarkar, B, Pradhan, A, Munshi, A, Roy, S, Ganesh, T, Mohanti, B. EP-1685: Influence of flat, flattening filter free beam model and different MLC’s on VMAT based SRS/SRT. Radiother Oncol 2016; 119: S787.
11. Timmerman, R D, Kavanagh, B D, Cho, L C, Papiez, L, Xing, L. Stereotactic body radiation therapy in multiple organ sites. J Clin Oncol 2007; 25: 947952.
12. Rusthoven, K E, Kavanagh, B D, Cardenes, H et al. Multi-institutional phase I/II trial of stereotactic body radiation therapy for liver metastases. J Clin Oncol 2009; 27 (10): 15721578.
13. Lee, M T, Kim, J J, Dinniwell, R et al. Phase I study of individualized stereotactic body radiotherapy of liver metastases. J Clin Oncol 2009; 27 (10): 15851591.
14. Macdermed, D M, Weichselbaum, R R, Salama, J K. A rationale for the targeted treatment of oligometastases with radiotherapy. J Surg Oncol 2008; 98: 202206.
15. Cai, J, Malhotra, H K, Orton, C G. A 3D-conformal technique is better than IMRT or VMAT for lung SBRT. Med Phys 2014; 41 (4): 040601.
16. de Pooter, J A, Romero, A M, Wunderink, W, Storchi, P R, Heijmen, B J. Automated non-coplanar beam direction optimization improves IMRT in SBRT of liver metastasis. Radiother Oncol 2008; 88 (3): 376381.
17. Milano, M T, Katz, A W, Muhs, A G et al. A prospective pilot study of curative-intent stereotactic body radiation therapy in patients with 5 or fewer oligometastatic lesions. Cancer: Interdiscip Int J Am Cancer Soc 2008; 112 (3): 650658.
18. Paddick, I. A simple scoring ratio to index the conformity of radiosurgical treatment plans: technical note. J Neurosurg 2000; 93 (Supplement 3): 219222.
19. Dzierma, Y, Bell, K, Palm, J, Nuesken, F, Licht, N, Rübe, C. mARC vs. IMRT radiotherapy of the prostate with flat and flattening-filter-free beam energies. Radiat Oncol 2014; 9 (1): 250.
20. Thomas, E M, Popple, R A, Prendergast, B M, Clark, G M, Dobelbower, M C, Fiveash, J B. Effects of flattening filter-free and volumetric-modulated arc therapy delivery on treatment efficiency. J Appl Clin Med Phys 2013; 14: 4328.
21. Sarkar, B, Pradhan, A, Munshi, A. Do technological advances in linear accelerators improve dosimetric outcomes in stereotaxy? A head-on comparison of seven linear accelerators using volumetric modulated arc therapy-based stereotactic planning. Indian J Cancer 2016; 53 (1): 166173.
22. Manikandan, A, Sarkar, B, Holla, R, Vivek, T R, Sujatha, N. Quality assurance of dynamic parameters in volumetric modulated arc therapy. Br J Radiol 2012; 85 (1015): 10021010.
23. Fong, Y, Fortner, J, Sun, R L, Brennan, M F, Blumgart, L H. Clinical score for predicting recurrence after hepatic resection for metastatic colorectal cancer: analysis of 1001 consecutive cases. Ann Surg 1999; 230 (3): 309.
24. Shah, S A, Bromberg, R, Coates, A, Rempel, E, Simunovic, M, Gallinger, S. Survival after liver resection for metastatic colorectal carcinoma in a large population. J Am Coll Surg 2007; 205 (5): 676683.
25. Aloia, T A, Vauthey, J N, Loyer, E M et al. Solitary colorectal liver metastasis: resection determines outcome. Arch Surg 2006; 141 (5): 460467.



Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed