A Step to In Vivo Dosimetry Using Electronic Portal Imaging Device: Initial Experience
Purpose In vivo dosimetry in radiotherapy for advanced treatment techniques is not in a regular clinical procedure. The purpose of the study is to verify the exit dose conformity and consistency for the advanced radiotherapy treatment delivery using electronic portal imaging device (EPID) and to implement in vivo dosimetry using EPID into our regular clinical procedures. Procedures Varian Trilogy linear accelerator attached with amorphous silicon EPID and on-board imager (OBI) having 120-leaf Millennium MLC was used for study. Three static fields and four dynamic multileaf collimator (MLC) fluence fields were planned using 6 MV X-rays for phantom study. We used catphan 500 phantom for our study. Four patients were chosen with intensity-modulated radiotherapy (IMRT) and volumetric arc therapy (VMAT) for in vivo dosimetry. Exit field treatment images were acquired using EPID during treatment in an integration mode. Portal dosimetry workspace was used to analyse and to record the results. Gamma analysis and dose comparison was done for individual fields and composite fields. Results The study shows the point dose comparison at isocentre and line profiles across the fields matched very well, if the treatment set-up was kept accurately and maintained the anatomy. Known shift was introduced into the field and recognized the change in the point dose and line profile dose in the phantom study. The IMRT and VMAT techniques exit field fluence image acquired by EPID shown, consistency in the treatment delivery. Conclusion EPID can be used for our in vivo dosimetry in high-end and complex radiotherapy techniques. This can be used for documenting and recording the treatment delivery of our radiotherapy patients. The results and analysis are comparatively reliable and took less time for acquired image analysis.
KeywordsRadiotherapy Electronic Portal Imaging Device (EPID) In vivo dosimetry Quality assurance Linear accelerator
Conflict of Interest
The authors declare that they have no conflict of interest.
- 1.ICRU Report 83 (2010) Prescribing, recording and reporting photon-beam intensity-modulated radiation therapy (IMRT) J ICRU, pp. 1–106Google Scholar
- 2.Ezzell GA, Galvin JM, Low D, et al (2003) Guidance document on delivery, treatment planning, and clinical implementation of IMRT: report of the IMRT subcommittee of the AAPM radiation therapy committee Med Phys. 30(8):2089–2115Google Scholar
- 6.International Atomic Energy Agency (2013) Development of procedures for in vivo dosimetry in radiotherapy, IAEA Human Health Report No. 8. (International Atomic Energy Agency, IAEA, Vienna, Austria)Google Scholar
- 10.Report of TG 62 of the Radiation Therapy Committee (2005) Diode in vivo dosimetry for patients receiving external beam radiation therapy, AAPM Report No. 87 (Medical Physics Publishing, Madison, WI)Google Scholar
- 13.Pai S, Das IJ, Dempsey JF et al (2007) TG-69: Radiographic film for megavoltage beam dosimetry. Med Phys 34(2228):2258Google Scholar
- 16.Naiyanet N, Oonsiri S, Lertbutsayanukul C, et al (2007) Measurements of patient’s setup variation in intensity-modulated radiation therapy of head and neck cancer using electronic portal imaging device. Biomed Imaging Interv J 3(1):e30Google Scholar
- 21.Oliva F, Celi S, Husson F, Diaz JC (2014) Influence of patient setup in the context of EPID-based in vivo dosimetry [poster]. In: Presented at the 13th international conference on electronic patient imaging 2014, AarhusGoogle Scholar