Abstract
The transit in vivo dosimetry performed by an electronic portal imaging device (EPID) is a very practical method to check error sources in radiotherapy. Recently, the present authors have developed an in vivo dosimetry method based on correlation functions, F (w, L), defined as the ratio between the transit signal, S t (w, L), by the EPID and the mid-plane dose, D m (w, L), in a solid water phantom as a function of the phantom thickness, w, and of the field dimensions, L. In particular, generalized correlation functions F (w, L) for 6, 10 and 15 MV X-ray beams supplied by a pilot Varian linac, are here used by other three linacs operating in two centers. This way the workload, due to measurements in solid water phantom, needed to implement the in vivo dosimetry method was avoided. This article reports a feasibility study on the potentiality of this procedure for the adaptive radiotherapy of lung tumors treated by 3D conformal radiotherapy techniques. In particular, the dose reconstruction at the isocenter point D iso in the lung tumor has been used as dose-guided radiotherapy (DGRT), to detect the inter-fraction tumor anatomy variations that can require new CT scans and an adaptive plan. When a difference greater than 6% between the predicted dose by the treatment planning system (TPS), D iso,TPS and the D iso was observed, the clinical action started to detect possible anatomical lung tumor changes. Twelve over twenty patients examined presented in vivo dose discrepancies due to the tumor morphological changes during treatments, and these results were successively confirmed by new CT scans. In this work, for a patient that showed for all beams, D iso values over the tolerance level, the new CT scan was used for an adaptive plan. The lung dose volume histogram for D iso,TPS = 2 Gy per fraction suggested the adaptive plan. In particular, the lung volume included in 2 Gy increased from 350 cm3 of the original plan to 550 cm3 of the hybrid plan, while for the adaptive plan the lung volume included in 2 Gy decreased to 15 cm3. Moreover, the mean doses to the organs at risk were reduced to 70%. The results of this research show that the DGRT procedure by the D iso reconstruction, integrated with radiological imaging, was feasible for periodic investigation on morphological lung tumor changes. This feasibility study takes into account the accuracy of two algorithms based on the pencil beam and collapsed cone convolution models for dose calculations where large density inhomogeneities are present.
Similar content being viewed by others
References
BJR (1996) Central axis depth dose data for use in radiotherapy. British Institute of Radiology, London, supplement 25
De Jaeger K, Hoogeman MS, Engelsman M, Seppenwoolde Y, Damen EMF, Mijnheer BJ, Boersma LJ, Lebesque JV (2003) Incorporating an improved dose-calculation algorithm in conformal radiotherapy of lung cancer: re-evaluation of dose in normal lung tissue. Radiother Oncol 69:1–10
Erridge SC, Seppenwoolde Y, Muller SH et al (2003) Portal imaging to assess set-up errors, tumor motion, and tumor shrinkage during conformal radiotherapy of non-small cell lung cancer. Radiother Oncol 66:75–85
Fidanzio A, Mameli A, Placidi E, Greco F, Stimato G, Gaudino D, Ramella S, D’Angelillo R, Cellini F, Trodella L, Cilla S, Grimaldi L, D’Onofrio G, Azario L, Piermattei A (2008) EPID cine acquisition mode for in vivo dosimetry in dynamic arc radiation therapy. Nucl Instr Methods Phys Res B 266:658–666
Grimaldi L, D’Onofrio G, Cilla S, Fidanzio A, Stimato G, Azario L, Deodato F, Macchia G, Morganti A, Piermattei A (2007) Breast in vivo dosimetry by a portal ionization chamber. Med Phys 34:1121–1127
Hasenbalg F, Neuenschwander H, Mini R, Born EJ (2007) Collapsed cone and analytical anisotropic algorithm dose calculations compared to VMC++ Monte Carlo simulations in clinical cases. J Phys 74:3679–3691
Hugo GD, Yan D, Liang J (2007) Population and patient-specific target margins for 4D adaptive radiotherapy to account for intra- and inter-fraction variation in lung tumor position. Phys Med Biol 52:257–274
IAEA (International Atomic Energy Agency) (2004) Absorbed dose in external beam radiotherapy: an international code of practice for dosimetry based on standards of absorbed dose to water. Technical reports series No. 398. IAEA, Vienna
ICRU Report 62 (1990) Prescribing, recording and reporting photon beam therapy (supplement to ICRU Report 50). ICRU, Bethesda
Kavuma A, Glegg M, Currie G, Elliott A (2008) Assessment of dosimetrical performance in 11 Varian a-Si-500 electronic portal imaging devices. Phys Med Biol 53:6893–6900
Krieger T, Sauer OA (2005) Monte Carlo versus pencil beam/collapsed cone dose calculation in a heterogeneous multi-layer phantom. Phys Med Biol 50:859–868
Kupelian PA, Ramsey C, Meeks SL, Willoughby TR, Forbes A, Wagner TH, Langen KM (2005) Serial megavoltage CT imaging during external beam radiotherapy for non-small-cell lung cancer: observations on tumor regression during treatment. Int J Radiat Oncol Biol Phys 63:1024–1028
Martel MK, Ten Haken RK, Hazuka MB, Kessler ML, Strawderman M, Turrisi AT, Lawrence TS, Fraass BA, Lichter AS (1999) Estimation of tumor control probability model parameters from 3-D dose distributions of non small cell lung cancer patients. Lung Cancer 24:31–37
Mijnheer B (2008) State of the art of in vivo dosimetry. Radiation Protection Dosimetry 131:117–122
Morganti AG, Deodato F, Zizzari S, Cilla S, Digesù C, Macchia G, Panunzi S, De Gaetano A, Piermattei A, Cellini N, Valentini V (2009) Complexity index (COMIX) and not type of treatment predicts undetected errors in radiotherapy planning and delivery. Radiother Oncol 89:320–329
Nijsten SM, Mijnheer BJ, Dekker AL, Lambin P, Minken AWH (2007) Routine individualised patient dosimetry using electronic portal imaging devices. Radiother Oncol 83:65–75
Piermattei A, Fidanzio A, Stimato G, Azario L, Grimaldi L, D’Onofrio G, Cilla S (2006) In vivo dosimetry by an aSi-based EPID. Med Phys 33:4414–4422
Piermattei A, Fidanzio A, Azario L et al (2007) Application of a practical method for the isocenter point in vivo dosimetry by a transit signal. Phys Med Biol 52:5101–5117
Piermattei A, Fidanzio A, Azario L, Greco F et al (2009) In patient dose reconstruction using cine acquisition for dynamic arc radiation therapy. Med Biol Eng Comput 47:425–433
Piermattei A, Cilla S, Grimaldi L, Viola P, Frattarolo L, D’Onofrio G et al (2008) Real time dosimetry reconstruction for the breath hold radiotherapy technique: an initial experience. Acta Oncologica 47:1414–1421
Ramsey C, Mahan S, Scaperoth D, Chase D (2004) Image-guided adaptive therapy for the treatment of lung cancer. Int J Radiat Oncol Biol Phys 60:S339
Ramsey CR, Langen KM, Kupelian PA, Scaperoth DD, Meeks SL, Mahan SL, Seibert RM (2006) A technique for adaptive image-guided helical tomotherapy for lung cancer. Int J Radiat Oncol Biol Phys 64:1237–1244
Siebers JV, Kim JO, Ko L, Keall PJ, Mohan R (2004) Monte Carlo computation of dosimetric amorphous silicon electronic portal images. Med Phys 31(7):2135–2146
Siker ML, Tomè WA, Mehta MP (2006) Tumor volume changes on serial imaging with megavoltage CT for non-small-cell lung cancer during intensity-modulated radiotherapy: how reliable, consistent and meaningful is the effect? Int J Radiat Oncol Biol Phys 66:135–141
SSI (2000) The Swedish Radiation Protection Institute’s regulations on radiation therapy. SSTFS, Swedish Radiation Protection Authority, Stockholm
van Elmpt W, McDermott L, Nijsten S, Wendling M, Lambin P, Mijnheer B (2008) A literature review of electronic portal imaging for radiotherapy dosimetry. Radiother Oncol 88:289–309
Van Esch A, Depuydt T, Huyskens DP (2004) The use of an aSi-based EPID for routine absolute dosimetric pre-treatment verification of dynamic IMRT fields. Radiother Oncol 71:223–224
Varian MS. PortalVision™ aS500 (2000) Rel. 6. Reference manual
Yartsev S, Dar AR, Woodford C, Wong E, Bauman G, Van Dyk J (2007) Initial experience in treating lung cancer with helical tomotherapy. Biomed Imaging Interv J 3(1):e2
Acknowledgments
We are grateful to Nucletron, (Italy) for their technical assistance. This work was financially supported by the B-MIUR Project no 4210011 ‘Sviluppo di nuovi approcci terapeutici al problema clinico della resistenza alla chemioterapia antitumorale’.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Piermattei, A., Fidanzio, A., Cilla, S. et al. Dose-guided radiotherapy for lung tumors. Med Biol Eng Comput 48, 79–86 (2010). https://doi.org/10.1007/s11517-009-0558-5
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11517-009-0558-5