Expected clinical impact of the differences between planned and delivered dose distributions in helical tomotherapy for treating head and neck cancer using helical megavoltage CT images.
Helical Tomotherapy (HT) has become increasingly popular over the past few years. However, its clinical efficacy and effectiveness continues to be investigated. Pre-treatment patient repositioning in highly conformal image-guided radiation therapy modalities is a prerequisite for reducing setup uncertainties. A MVCT image set has to be acquired to account for daily changes in the patient's internal anatomy and setup position. Furthermore, a comparison should be performed to the kVCT study used for dosimetric planning, by a registration process which results in repositioning the patient according to specific transitional and rotational shifts. Different image registration techniques may lead to different repositioning of the patient and, as a result, to varying delivered doses. This study aims to investigate the expected effect of patient setup correction using the Hi-Art tomotherapy system by employing radiobiological measures such as the biologically effective uniform dose (BEUD) and the complication-free tumor control probability (P+). In this study, a typical case of lung cancer with metastatic head & neck disease was investigated by developing a Helical Tomotherapy plan. For the Tomotherapy HiArt plan, the dedicated Tomotherapy treatment planning station was used. Three dose distributions (planned and delivered with and without patient setup correction) were compared based on radiobiological measures by using the P+ index and the BEUD concept as the common prescription point of the plans and plotting the tissue response probabilities against the mean target dose for a range of prescription doses. The applied plan evaluation method shows that in this cancer case the planned and delivered dose distributions with and without patient setup correction give a P+ of 81.6%, 80.9% and 72.2%, for a BEUD to the planning target volume (PTV) of 78.0Gy, 77.7Gy and 75.4Gy, respectively. The corresponding tumor control probabilities are 86.3%, 85.1% and 75.1%, whereas the total complication probabilities are 4.64%, 4.20% and 2.89%, respectively. HT can encompass the often large PTV required while minimizing the volume of the organs at risk receiving high dose. However, the effectiveness of a HT treatment plan can be considerably deteriorated if an accurate patient setup system is not available. Taking into account the dose-response relations of the irradiated tumors and normal tissues, a radiobiological treatment plan evaluation can be performed, which may provide a closer association of the delivered treatment with the clinical outcome. In such situations, for effective evaluation and comparison of different treatment plans, traditional dose based evaluation tools can be complemented by the use of P+,BEUD diagrams.
Mavroidis
Panayiotis
P
Department of Medical Radiation Physics, Karolinska Institutet and Stockholm University, Stockholm, Sweden.|Department of Medical Physics, Larissa University Hospital, Larissa, Greece.
Stathakis
Sotirios
S
Department of Radiological Sciences, University of Texas Health Sciences Center, San Antonio, TX, USA.
Gutierrez
Alonso
A
Department of Radiological Sciences, University of Texas Health Sciences Center, San Antonio, TX, USA.
Esquivel
Carlos
C
Department of Radiological Sciences, University of Texas Health Sciences Center, San Antonio, TX, USA.
Shi
Chenyu
C
Department of Radiological Sciences, University of Texas Health Sciences Center, San Antonio, TX, USA.
Papanikolaou
Nikos
N
Department of Radiological Sciences, University of Texas Health Sciences Center, San Antonio, TX, USA.
D000368:Aged; D006258:Head and Neck Neoplasms / Q000532:radiotherapy*; D006801:Humans; D008297:Male; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D036542:Tomography, Spiral Computed / Q000379:methods*
Acta Oncol. 1993;32(3):331-42
8323773
Int J Radiat Oncol Biol Phys. 1991 May 15;21(1):123-35
2032883
Int J Radiat Oncol Biol Phys. 2000 Jan 15;46(2):373-81
10661344
Med Phys. 1993 Nov-Dec;20(6):1709-19
8309444
Int J Radiat Oncol Biol Phys. 1993 Feb 15;25(3):529-39
8436532
Semin Radiat Oncol. 1999 Jan;9(1):108-17
10196402
Acta Oncol. 1999;38(6):787-98
10522770
Acta Oncol. 1997;36(sup10):1-32
28173715
Acta Oncol. 2000;39(5):579-95
11093366
Radiother Oncol. 1998 Jul;48(1):61-9
9756173
Technol Cancer Res Treat. 2006 Oct;5(5):465-79
16981789
Med Phys. 2005 May;32(5):1414-23
15984692
Radiother Oncol. 1991 Dec;22(4):308-10
1792326
Phys Med Biol. 2000 Jan;45(1):69-90
10661584
Med Phys. 1997 Jan;24(1):103-10
9029544
Strahlenther Onkol. 2005 May;181(5):293-306
15900425
Technol Cancer Res Treat. 2002 Aug;1(4):311-6
12625791
Acta Oncol. 1997;36(8):789-92
9482683
Med Phys. 1996 Aug;23(8):1393-8
8873036
Phys Med Biol. 2001 Oct;46(10):2607-30
11686278
Int J Radiat Oncol Biol Phys. 2001 Aug 1;50(5):1113-22
11483320
Radiother Oncol. 2000 May;55(2):153-62
10799727
Phys Med Biol. 1992 Apr;37(4):871-90
1589457
Med Phys. 2006 Nov;33(11):4395-404
17153418
Phys Med Biol. 2000 Sep;45(9):2459-81
11008949
Med Phys. 2005 Aug;32(8):2673-81
16193798
Int J Radiat Oncol Biol Phys. 1991 May 15;21(1):109-22
2032882
Phys Med Biol. 2001 Jul;46(7):1815-34
11474927
Technol Cancer Res Treat. 2008 Aug;7(4):279-85
18642966
Radiother Oncol. 1993 Nov;29(2):253-60
8310153
Acta Oncol. 2003;42(8):865-81
14968948
Int J Radiat Oncol Biol Phys. 2002 Feb 1;52(2):382-9
11872283
Acta Radiol Oncol. 1984;23(5):379-91
6095609
Radiother Oncol. 2006 Oct;81(1):81-7
17005280
Radiother Oncol. 1995 Jul;36(1):15-23
8525021
Int J Radiat Oncol Biol Phys. 2001 Nov 15;51(4):938-46
11704314
Phys Med Biol. 2007 Feb 21;52(4):1055-73
17264370
Strahlenther Onkol. 2000 Mar;176(3):105-11
10742830
Int J Radiat Oncol Biol Phys. 2003 Oct 1;57(2):391-401
12957250
Med Phys. 2006 Dec;33(12):4710-7
17278823
Int J Radiat Oncol Biol Phys. 1991 May 15;21(1):137-46
2032884