Intraoperative computed tomography imaging for dose calculation in intraoperative electron radiation therapy: Initial clinical observations

Autoři: Verónica García-Vázquez aff001;  Felipe A. Calvo aff001;  María J. Ledesma-Carbayo aff005;  Claudio V. Sole aff001;  José Calvo-Haro aff001;  Manuel Desco aff001;  Javier Pascau aff001
Působiště autorů: Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Comunidad de Madrid, Spain aff001;  Departamento de Oncología, Hospital General Universitario Gregorio Marañón, Madrid, Comunidad de Madrid, Spain aff002;  Facultad de Medicina, Universidad Complutense de Madrid, Madrid, Comunidad de Madrid, Spain aff003;  Clínica Universidad de Navarra, Madrid, Comunidad de Madrid, Spain aff004;  Biomedical Image Technologies Laboratory (BIT), Escuela Técnica Superior de Ingenieros de Telecomunicación, Universidad Politécnica de Madrid, Madrid, Comunidad de Madrid, Spain aff005;  CIBER-BBN, Madrid, Comunidad de Madrid, Spain aff006;  Department of Radiation Oncology, Instituto de Radiomedicina, Santiago, Región Metropolitana de Santiago, Chile aff007;  Servicio de Cirugía Ortopédica y Traumatología, Hospital General Universitario Gregorio Marañón, Madrid, Comunidad de Madrid, Spain aff008;  Departamento de Cirugía, Facultad de Medicina, Universidad Complutense de Madrid, Madrid, Comunidad de Madrid, Spain aff009;  Departamento de Bioingeniería e Ingeniería Aeroespacial, Universidad Carlos III de Madrid, Madrid, Comunidad de Madrid, Spain aff010;  Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), Madrid, Comunidad de Madrid, Spain aff011;  Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Comunidad de Madrid, Spain aff012
Vyšlo v časopise: PLoS ONE 15(1)
Kategorie: Research Article
doi: 10.1371/journal.pone.0227155


In intraoperative electron radiation therapy (IOERT) the energy of the electron beam is selected under the conventional assumption of water-equivalent tissues at the applicator end. However, the treatment field can deviate from the theoretic flat irradiation surface, thus altering dose profiles. This patient-based study explored the feasibility of acquiring intraoperative computed tomography (CT) studies for calculating three-dimensional dose distributions with two factors not included in the conventional assumption, namely the air gap from the applicator end to the irradiation surface and tissue heterogeneity. In addition, dose distributions under the conventional assumption and from preoperative CT studies (both also updated with intraoperative data) were calculated to explore whether there are other alternatives to intraoperative CT studies that can provide similar dose distributions. The IOERT protocol was modified to incorporate the acquisition of intraoperative CT studies before radiation delivery in six patients. Three studies were not valid to calculate dose distributions due to the presence of metal artefacts. For the remaining three cases, the average gamma pass rates between the doses calculated from intraoperative CT studies and those obtained assuming water-equivalent tissues or from preoperative CT studies were 73.4% and 74.0% respectively. The agreement increased when the air gap was included in the conventional assumption (98.1%) or in the preoperative CT images (98.4%). Therefore, this factor was the one mostly influencing the dose distributions of this study. Our experience has shown that intraoperative CT studies are not recommended when the procedure includes the use of shielding discs or surgical retractors unless metal artefacts are removed. IOERT dose distributions calculated under the conventional assumption or from preoperative CT studies may be inaccurate unless the air gap (which depends on the surface irregularities of the irradiated volume and on the applicator pose) is included in the calculations.

Klíčová slova:

Breast cancer – Cancer treatment – Computed axial tomography – Image processing – Radiation therapy – Surgical and invasive medical procedures – Surgical oncology – Tissue distribution


1. Calvo FA, Meirino RM, Orecchia R. Intraoperative radiation therapy. First part: rationale and techniques. Crit Rev Oncol Hematol. 2006;59: 106–115. doi: 10.1016/j.critrevonc.2005.11.004 16844383

2. Calvo FA. Intraoperative irradiation: precision medicine for quality cancer control promotion. Radiat Oncol. 2017;12: 36. doi: 10.1186/s13014-017-0764-5 28148287

3. Gunderson LL, Calvo FA, Willett CG, Harrison LB. Rationale and historical perspective of intraoperative irradiation. In: Gunderson LL, Willett CG, Calvo FA, Harrison LB, editors. Intraoperative irradiation: techniques and results. New York: Humana Press; 2011. pp. 3–26.

4. Pascau J, Santos Miranda JA, Calvo FA, Bouché A, Morillo V, González-San Segundo C, et al. An innovative tool for intraoperative electron beam radiotherapy simulation and planning: description and initial evaluation by radiation oncologists. Int J Radiat Oncol Biol Phys. 2012;83: e287–e295. doi: 10.1016/j.ijrobp.2011.12.063 22401923

5. Valdivieso-Casique MF, Rodríguez R, Rodríguez-Bescós S, Lardíes D, Guerra P, Ledesma MJ, et al. RADIANCE–A planning software for intra-operative radiation therapy. Transl Cancer Res. 2015;4: 196–209. doi: 10.3978/j.issn.2218-676X.2015.04.05

6. Alhamada H, Simon S, Philippson C, Vandekerkhove C, Jourani Y, Pauly N, et al. 3D Monte Carlo dosimetry of intraoperative electron radiation therapy (IOERT). Phys Med. 2019;57: 207–214. doi: 10.1016/j.ejmp.2018.12.037 30738527

7. Costa F, Sarmento S, Sousa O. Assessment of clinically relevant dose distributions in pelvic IOERT using Gafchromic EBT3 films. Phys Med. 2015;31: 692–701. doi: 10.1016/j.ejmp.2015.05.013 26078013

8. Calvo FA, Sole CV, González ME, Tangco ED, López-Tarjuelo J, Koubychine I, et al. Research opportunities in intraoperative radiation therapy: the next decade 2013–2023. Clin Transl Oncol 2013;15: 683–690. doi: 10.1007/s12094-013-1019-z 23463592

9. Trifiletti DM, Jones R, Showalter SL, Libby BB, Brenin DR, Schroen A, et al. Techniques for intraoperative radiation therapy for early-stage breast carcinoma. Future Oncol. 2015;11: 1047–1058. doi: 10.2217/fon.15.26 25804120

10. Pascau J, Santos-Miranda J, González San-Segundo C, Illana C, Valdivieso M, García-Vazquez V, et al. Intraoperative imaging in IOERT sarcoma treatment: initial experience in two clinical cases. Int J Radiat Oncol Biol Phys. 2011;81: S90. doi: 10.1016/j.ijrobp.2011.06.184

11. Low DA, Harms WB, Mutic S, Purdy JA. A technique for the quantitative evaluation of dose distributions. Med Phys. 1998;25: 656–661. doi: 10.1118/1.598248 9608475

12. Guerra P, Udías JM, Herranz E, Santos-Miranda JA, Herraiz JL, Valdivieso MF, et al. Feasibility assessment of the interactive use of a Monte Carlo algorithm in treatment planning for intraoperative electron radiation therapy. Phys Med Biol. 2014;59: 7159–7179. doi: 10.1088/0031-9155/59/23/7159 25365625

13. Nemoto K, Seiji K, Sasaki K, Kasamatsu N, Fujishima T, Ogawa Y, et al. A novel support system for patient immobilization and transportation for daily computed tomographic localization of target prior to radiation therapy. Int J Radiat Oncol Biol Phys. 2003;55: 1102–1108. doi: 10.1016/s0360-3016(02)04513-3 12605990

14. Pascau J, Vaquero J, Abella M, Cacho R, Lage E, Desco M. Multimodality workstation for small animal image visualization and analysis. Mol Imaging Biol. 2006;8 97–98. doi: 10.1007/s11307-006-0031-x

15. Gonzalez RC, Woods RE. Digital image processing. 3rd ed. Upper Saddle River: Pearson/Prentice Hall; 2008.

16. Pascau J, Gispert JD, Michaelides M, Thanos PK, Volkow ND, Vaquero JJ, et al. Automated method for small-animal PET image registration with intrinsic validation. Mol Imaging Biol. 2009;11: 107–113. doi: 10.1007/s11307-008-0166-z 18670824

17. Herranz E, Herraiz JL, Ibáñez P, Pérez-Liva M, Puebla R, Cal-González J, et al. Phase space determination from measured dose data for intraoperative electron radiation therapy. Phys Med Biol. 2015;60: 375–401. doi: 10.1088/0031-9155/60/1/375 25503853

18. García-Vázquez V, Marinetto E, Guerra P, Valdivieso-Casique MF, Calvo FÁ, Alvarado-Vásquez E, et al. Assessment of intraoperative 3D imaging alternatives for IOERT dose estimation. Z Med Phys. 2017;27: 218–231. doi: 10.1016/j.zemedi.2016.07.002 27567405

19. Bresciani S, Di Dia A, Maggio A, Cutaia C, Miranti A, Infusino E, et al. Tomotherapy treatment plan quality assurance: the impact of applied criteria on passing rate in gamma index method. Med Phys. 2013;40: 121711. doi: 10.1118/1.4829515 24320497

20. López-Tarjuelo J, Bouché-Babiloni A, Santos-Serra A, Morillo-Macías V, Calvo FA, Kubyshin Y, et al. Failure mode and effect analysis oriented to risk-reduction interventions in intraoperative electron radiation therapy: the specific impact of patient transportation, automation, and treatment planning availability. Radiother Oncol. 2014;113: 283–289. doi: 10.1016/j.radonc.2014.11.012 25465728

21. Hensley FW. Present state and issues in IORT physics. Radiat Oncol. 2017;12: 37. doi: 10.1186/s13014-016-0754-z 28193241

22. Oshima T, Aoyama Y, Shimozato T, Sawaki M, Imai T, Ito Y, et al. An experimental attenuation plate to improve the dose distribution in intraoperative electron beam radiotherapy for breast cancer. Phys Med Biol. 2009;54: 3491–3500. doi: 10.1088/0031-9155/54/11/014 19436105

23. Rankin TM, Giovinco NA, Cucher DJ, Watts G, Hurwitz B, Armstrong DG. Three-dimensional printing surgical instruments: are we there yet? J Surg Res. 2014;189: 193–197. doi: 10.1016/j.jss.2014.02.020 24721602

24. Giantsoudi D, De Man B, Verburg J, Trofimov A, Jin Y, Wang G, et al. Metal artifacts in computed tomography for radiation therapy planning: dosimetric effects and impact of metal artifact reduction. Phys Med Biol. 2017;62: R49–R80. doi: 10.1088/1361-6560/aa5293 28323641

25. Costa F, Sarmento S, Gomes D, Magalhães H, Arrais R, Moreira G, et al. In vivo dosimetry using Gafchromic films during pelvic intraoperative electron radiation therapy (IOERT). Br J Radiol. 2016;89: 20160193. doi: 10.1259/bjr.20160193 27188847

26. Khan FM, Gibbons JP. Electron beam therapy. In: Pine JW Jr, Moyer E, editors. Khan's the physics of radiation therapy. Philadelphia: Lippincott Williams & Wilkins; 2014. pp. 256–308.

27. Consorti R, Petrucci A, Fortunato F, Soriani A, Marzi S, Iaccarino G, et al. In vivo dosimetry with MOSFETs: dosimetric characterization and first clinical results in intraoperative radiotherapy. Int J Radiat Oncol Biol Phys. 2005;63: 952–960. doi: 10.1016/j.ijrobp.2005.02.049 16199324

28. Soriani A, Iaccarino G, Felici G, Ciccotelli A, Pinnarò P, Giordano C, et al. Development and optimization of a beam shaper device for a mobile dedicated IOERT accelerator. Med Phys. 2012;39: 6080–6089. doi: 10.1118/1.4749968 23039647

29. García-Vázquez V, Sesé-Lucio B, Calvo FA, Vaquero JJ, Desco M, Pascau J. Surface scanning for 3D dose calculation in intraoperative electron radiation therapy. Radiat Oncol. 2018;13: 243. doi: 10.1186/s13014-018-1181-0 30526626

Článek vyšel v časopise


2020 Číslo 1