Author of

• 10692

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  P1.08 - Poster Session 1 - Radiotherapy (ID 195)

  • Event: WCLC 2013
  • Type: Poster Session
  • Track: Radiation Oncology + Radiotherapy
  • Presentations: 1
  • Moderators:
  • Coordinates: 10/28/2013, 09:30 - 16:30, Exhibit Hall, Ground Level

  • 10701

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    P1.08-009 - Dynamic Tumor Tracking Radiotherapy with Real-Time Monitoring using Vero4DRT (ID 929)

    09:30 - 09:30  |  Author(s): Y. Miyabe
    • Abstract

    Background
    The Vero4DRT is a newly-developed innovative radiotherapy system with two special features. One is a pair of kV x-ray imagers which can monitor a 3-dimensional position of tumor in real time. The other is a gimbaled x-ray head which enables tumor tracking. This study is to evaluate the initial clinical experiences of dynamic tumor tracking irradiation with real-time monitoring for the lung using the Vero4DRT system.

    Methods
    Eligibility criteria for this study were (1) lung tumor with a diameter of 50 mm or less, (2) respiratory motion of 10 mm or more, (3) performance status of 0–2, and (4) written informed consent. Prior to treatment planning, spherical gold markers were placed around the tumor using a bronchoscope. Gross tumor volume (GTV) for tracking was delineated on a breath-hold CT at end-exhale. Margins for planning target volume (PTV) were determined for each patient considering errors due to the tracking irradiation. Prescription dose was 56 Gy in 4 fractions for T2a lung cancer and metastatic tumor, and 48 Gy in 4 fractions for the others. Dose-volume metrics were compared between the tumor tracking and conventional static irradiation using an in-house developed software. A 6-MV photon beam was delivered to the tumor with the gimbaled x-ray head toward predicted position based on the abdominal wall. During the irradiation, the tumor and the gold markers were monitored with kV imagers and EPID.

    Results
    The dynamic tumor tracking radiotherapy was successfully performed for 12 patients (10 males and 2 females). A median age was 83 years (range, 60-87 years). Histology was adenocarcinoma in 4 patients, squamous cell carcinoma in 3, non-small cell lung cancer in 1, metastatic tumor in 3, and unconfirmed in 2, respectively. Tumor diameter ranged from 12 to 36 mm (median, 21 mm). Median amplitude of respiratory motion was 16.8 mm (range, 11.3 to 33.5 mm). A mean PTV volume was 42.9 cc for the dynamic tracking, while that was 62.5 cc for the conventional irradiation. The tracking irradiation could reduce normal lung doses by 21.3% in mean. Dose covering 95% volume of GTV was not different between the two irradiation techniques with a mean difference of 0.66%. A mean treatment time per fraction was 37 minutes. The gold markers were well recognized with kV x-ray imagers through the whole treatment fractions. With a median follow-up period of 7.7 months (range, 2.1 – 19.2 months), local tumor was controlled in all patients. One patient experienced grade 2 radiation pneumonitis. No severe toxicity has been observed in any of the patients so far.

    Conclusion
    Dynamic tumor tracking irradiation with real-time monitoring using the Vero4DRT could reduce normal lung doses without any excess time. Preliminary outcomes were promising.