Research Article| Volume 107, 102550, March 2023

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A new target localization method for image-guided radiation therapy of prostate cancer

Published:March 03, 2023DOI:


      • Anatomy matching based target localization is problematic due to organ deformation.
      • A new method is proposed to align the target with the prescription-isodose surface.
      • Detailed analyses were based on in-room CT images before and post IMRT treatments.
      • The method can improve localization accuracy and critical structure sparing greatly.


      In imaged-guided radiation therapy (IGRT), target localization is usually done with rigid-body registration based on anatomy matching. Problems arise when the target volume can only be matched partially due to inter-fractional organ motion and deformation, resulting in deteriorated target coverage and critical structure sparing. A new target localization method is investigated in which the treatment target volume is aligned with the prescription isodose surface. Our study included 15 prostate patients previously treated with intensity-modulated radiation therapy (IMRT). Patient setup and target localization were performed using a CT-on-rails system before and after the IMRT treatment. IMRT plans were generated on the original simulation CTs (15) and the same MUs and leaf sequences were used to compute the dose distributions on post-treatment CTs (98) with the isocenter adjustments based on either anatomical structure matching or prescription isodose surface alignment. When patients were aligned with the traditional anatomy matching method, the dose to 95% of the CTV, D95, received 74.0 – 77.6 Gy and the minimum CTV dose, Dmin, was 61.9 – 71.6 Gy, respectively, in the cumulative dose distributions. The rectal dose-volume constraints were violated in 35.7% of the treatment fractions. When patients were aligned using the new localization method, the dose to 95% of the CTV, D95, received 74.0 – 78.2 Gy and the minimum CTV dose, Dmin, was 68.4 – 71.6 Gy, respectively, in the cumulative dose distributions. The rectal dose-volume constraints were violated in 17.3% of the treatment fractions. Traditional IGRT target localization based on anatomy matching is effective for population-based PTV margins but not ideal for those patients with large inter-fractional prostate rotation/deformation due to large rectal and bladder volume variation. The new method using the prescription isodose surface to align the target volume could improve the target coverage and rectal sparing for these patients, which can be implemented clinically to improve target dose delivery accuracy.


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        • Grégoire V.
        • Guckenberger M.
        • Haustermans K.
        • et al.
        Image guidance in radiation therapy for better cure of cancer.
        Mol Oncol. 2020; 14: 1470-1491
        • De Los Santos J.
        • Popple R.
        • Agazaryan N.
        • Bayouth J.E.
        • Bissonnette J.-P.
        • Bucci M.K.
        • et al.
        Image guided radiation therapy (IGRT) technologies for radiation therapy localization and delivery.
        Int J Radiat Oncol Biol Phys. 2013; 87: 33-45
        • Dang A.
        • Kupelian P.A.
        • Cao M.
        • Agazaryan N.
        • Kishan A.U.
        Image-guided radiotherapy for prostate cancer.
        Transl Androl Urol. 2018; 7: 308-320
        • Ma C.-M.
        Adaptive radiation therapy for prostate cancer.
        in: Allen Li X. Adaptive Radiation Therapy. CRC Press, New York2011: 331-350
      1. Ma C.-M, Physics and dosimetric principles of SRS and SBRT, Mathews J Cancer Sci. 4(2): 22,

        • Barney B.M.
        • Lee R.J.
        • Handrahan D.
        • Welsh K.T.
        • Cook J.T.
        • Sause W.T.
        Image-guided radiotherapy (IGRT) for prostate cancer comparing kV imaging of fiducial markers with cone beam computed tomography (CBCT).
        Int J Radiat Oncol Biol Phys. 2011; 80: 301-305
        • Ma C.-M.
        • Paskalev K.
        In-room CT techniques for image-guided radiation therapy.
        Med Dosimetry. 2006; 31: 30-39
        • Chen L.
        • Paskalev K.
        • Xu X.
        • Zhu J.
        • Wang L.
        • Price R.A.
        • et al.
        Rectal dose variation during the course of image-guided radiation therapy of prostate cancer.
        Radiother Oncol. 2010; 95: 198-202
        • Paskalev K.
        • Feigenberg S.
        • Jacob R.
        • et al.
        Target localization for post-prostatectomy patients using CT and ultrasound image guidance.
        J Appl Clin Med Phys. 2005; 6: 40-49
        • Tong X.
        • Chen X.
        • Li J.
        • et al.
        Intrafractional prostate motion during external beam radiotherapy monitored by a real-time target localization system.
        J Appl Clin Med Phys. 2015; 16: 51-60
        • Foster R.D.
        • Solberg T.D.
        • Li H.S.
        • Kerkhoff A.
        • Enke C.A.
        • Willoughby T.R.
        • et al.
        Comparison of transabdominal ultrasound and electromagnetic transponders for prostate localization.
        J Appl Clin Med Phys. 2010; 11: 57-67
        • Park S.S.
        • Yan D.i.
        • McGrath S.
        • Dilworth J.T.
        • Liang J.
        • Ye H.
        • et al.
        Adaptive image-guided radiotherapy (IGRT) eliminates the risk of biochemical failure caused by the bias of rectal distension in prostate cancer treatment planning: clinical evidence.
        Int J Radiat Oncol Biol Phys. 2012; 83: 947-952
        • Hall W.A.
        • Paulson E.S.
        • van der Heide U.A.
        • Fuller C.D.
        • Raaymakers B.W.
        • Lagendijk J.J.W.
        • et al.
        The transformation of radiation oncology using real-time magnetic resonance guidance: a review.
        Eur J Cancer. 2019; 122: 42-52
      2. Hehakaya C, Van der Voort van Zyp J, Lagendijk J, et al, Problems and promises of introducing the magnetic resonance imaging linear accelerator into routine care: the case of prostate cancer, Front Oncol, 2020 |

        • Moazzezi M.
        • Rose B.
        • Kisling K.
        • Moore K.L.
        • Ray X.
        Prospects for daily online adaptive radiotherapy via Ethos for prostate cancer patients without nodal involvement using unedited CBCT auto-segmentation.
        J Appl Clin Med Phys. 2021; 22: 82-93
        • van Herk M.
        • Remeijer P.
        • Rasch C.
        • Lebesque J.V.
        The probability of correct target dosage: Dose-population histograms for deriving treatment margins in radiotherapy.
        Int J Radiat Oncol Biol Phys. 2000; 47: 1121-1135
        • Beltran C.
        • Herman M.G.
        • Davis B.J.
        Planning target margin calculations for prostate radiotherapy based on intrafraction and interfraction motion using four localization methods.
        Int J Radiat Oncol Biol Phys. 2008; 70: 289-295
        • Zelefsky M.J.
        • Kollmeier M.
        • Cox B.
        • Fidaleo A.
        • Sperling D.
        • Pei X.
        • et al.
        Improved clinical outcomes with high-dose image guided radiotherapy compared with non-IGRT for the treatment of clinically localized prostate cancer.
        Int J Radiat Oncol Biol Phys. 2012; 84: 125-129
        • Engels B.
        • Soete G.
        • Verellen D.
        • et al.
        Conformal arc radiotherapy for prostate cancer: increased biochemical failure in patients with distended rectum on the planning computed tomogram despite image guidance by implanted markers.
        Int J Radiat Oncol Biol Phys. 2009; 74: 388-391
        • Pollack A.
        • Hanlon A.L.
        • Horwitz E.M.
        • Feigenberg S.J.
        • Konski A.A.
        • Movsas B.
        • et al.
        Dosimetry and preliminary acute toxicity in the first 100 men treated for prostate cancer on a randomized hypofractionation dose escalation trial.
        Int J Radiat Oncol Biol Phys. 2006; 64: 518-526
        • Shan G.
        • Hu W.
        • Chen L.
        • Price R.A.
        • Ma C.-M.
        Dosimetric evaluation of image-guided radiation therapy for prostate cancer.
        Med Dosim. 2021; 46: 117-126
        • Nassef M.
        • Simon A.
        • Cazoulat G.
        • Duménil A.
        • Blay C.
        • Lafond C.
        • et al.
        Quantification of dose uncertainties in cumulated dose estimation compared to planned dose in prostate IMRT.
        Radiother Oncol. 2016; 119: 129-136
        • Tome W.A.
        • Fowler J.F.
        On cold spots in tumor subvolumes.
        Med Phys. 2002; 29: 1590-2158
        • Feigenberg S.
        • Paskalev K.
        • McNeeley S.
        • et al.
        Comparing computed tomography localization with daily ultrasound during image-guided radiation therapy for the treatment of prostate cancer: a prospective evaluation.
        J Appl Clin Med Phys. 2007; 8: 99-110
        • Dearnaley D.P.
        • Jovic G.
        • Syndikus I.
        • et al.
        Escalated-dose versus control-dose conformal radiotherapy for prostate cancer: long-term results from the MRC RT01 randomised controlled trial.
        Lancet Oncol. 2014; 15: 464-473
        • Pasalic D.
        • Kuban D.A.
        • Allen P.K.
        • et al.
        Dose escalation for prostate adenocarcinoma: a long-term update on the outcomes of a phase3, Single Institution Randomized Clinical Trial.
        Int J Radiation Oncol Biol Phys. 2019; 104: 790-797
        • Kalbasi A.
        • Li J.
        • Berman A.T.
        • et al.
        Dose-escalated irradiation and overall survival in men with nonmetastatic prostate cancer.
        JAMA Oncol. 2015; 1: 897-906
        • Cellini N.
        • Morganti A.G.
        • Mattiucci G.C.
        • Valentini V.
        • Leone M.
        • Luzi S.
        • et al.
        Analysis of intraprostatic failures in patients treated with hormonal therapy and radiotherapy: Implications for conformal therapy planning.
        Int J Radiat Oncol Biol Phys. 2002; 53: 595-599
        • Pucar D.
        • Hricak H.
        • Shukla-Dave A.
        • Kuroiwa K.
        • Drobnjak M.
        • Eastham J.
        • et al.
        Clinically significant prostate cancer local recurrence after radiation therapy occurs at the site of primary tumor: magnetic resonance imaging and step-section pathology evidence.
        Int J Radiat Oncol Biol Phys. 2007; 69: 62-69
        • Arrayeh E.
        • Westphalen A.C.
        • Kurhanewicz J.
        • Roach M.
        • Jung A.J.
        • Carroll P.R.
        • et al.
        Does local recurrence of prostate cancer after radiation therapy occur at the site of primary tumor? Results of a longitudinal MRI and MRSI study.
        Int J Radiat Oncol Biol Phys. 2012; 82: e787-e793
        • Kontaxis C.
        • de Muinck Keizer D.M.
        • Kerkmeijer L.G.W.
        • et al.
        Delivered dose quantification in prostate radiotherapy using online 3D cine imaging and treatment log files on a combined 1.5T magnetic resonance imaging and linear accelerator system.
        Phys Imag Radiat Oncol. 2020; 15: 23-29
        • Wang L.
        • Feigenberg S.
        • Fan J.
        • Jin L.
        • Turaka A.
        • Chen L.
        • et al.
        Target relocalization accuracy and PTV margin verification using three-dimensional cone-beam computed tomography (CBCT) in stereotactic body radiotherapy (SBRT) of lung cancers.
        J Appl Clin Med Phys. 2012; 13: 41-54
        • Bohoudi O.
        • Bruynzeel A.M.E.
        • Meijerink M.R.
        • et al.
        Identification of patients with locally advancedpancreatic cancer benefitting from plan adaptation inMR-guided radiation therapy.
        Radiother Oncol. 2019; 132: 16-22
        • Nichol A.M.
        • Brock K.K.
        • Lockwood G.A.
        • et al.
        A magnetic resonance imaging study of prostate deformation relative to implanted gold fiducial markers.
        Int J Radiat Oncol Biol Phys. 2007; 67: 48-56
        • Shi C.
        • Tazi A.
        • Fang D.X.
        • et al.
        Study of ExacTrac X-ray 6D IGRT setup uncertainty for marker-based prostate IMRT treatment.
        J Appl Clin Med Phys. 2012; 13: 3757
        • O'Neill A.G.
        • Jain S.
        • Hounsell A.R.
        • O'Sullivan J.M.
        Fiducial marker guided prostate radiotherapy: a review.
        Br J Radiol. 2016; 89: 20160296
      3. Van de Water S., Valli L., Aluwini S., et al, Intrafraction prostate translations and rotations during hypofractionated robotic radiation surgery: dosimetric impact of correction strategies and margins. Int J Radiation Oncol Biol Phys, 2014; 88: 1154-1160.

        • Kron T.
        • Thomas J.
        • Fox C.
        • et al.
        Intra-fraction prostate displacement in radiotherapy estimated from pre- and post-treatment imaging of patients with implanted fiducial markers.
        Radiother Oncol. 2010; 95: 191-197
        • Mutanga T.F.
        • de Boer H.C.
        • Rajan V.
        • et al.
        Day-to-day reproducibility of prostate intrafraction motion assessed by multiple kV and MV imaging of implanted markers during treatment.
        Int J Radiat Oncol Biol Phys. 2012; 83: 400-407
        • Li J.S.
        • Jin L.
        • Pollack A.
        • et al.
        Gains from real-time tracking of prostate motion during external beam radiation therapy.
        Int J Radiat Oncol Biol Phys. 2009; 75: 1613-1620