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

  • 10718

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    P1.08-026 - Functional dosimetric metrics based on the ventilation and perfusion SPECT-CT during the course of radiotherapy and association with radiation-induced lung toxicity in patients with non-small-cell lung cancer (ID 3325)

    09:30 - 16:30  |  Author(s): F.(. Kong
    • Abstract

    Background
    To investigate volume changes in single photon emission computed tomography (SPECT) ventilation (V) and perfusion (Q) - weighted functional lung (FL), and dose-volume histogram of functional lung (FDVH) from V or Q SPECT and factors associated with radiation-induced lung toxicity (RILT) during the course of radiotherapy (RT) in patients with non-small-cell lung cancer (NSCLC).

    Methods
    Seventy NSCLC patients treated with definitive RT were enrolled prospectively. V and Q SPECT-computed tomography (CT) were performed prior to and during RT at approximately 45 Gy. FL was created from the whole lung (WL) in V and Q SPECT using a threshold of 30% of the maximum uptake of normal lung. Patients had dose calculated on CT scan to provide a standard dose-volume histogram (DVH). V and Q SPECT scans provided FDVH and functional dosimetric parameters. From the FDVH; the percent of FL receiving from 5 to 60 Gy and the mean doses of functional lungs (FMLD) were computed. Differences of volume and volume change of WL and FL between pre-RT and during-RT were compared. Differences of functional and standard dosimetric parameters between the patients with and without RILT were compared. Clinical fibrosis and pneumonitis were graded according to Common Terminology Criteria for Adverse Events version 3.0, grade 2 and above were considered to be clinically significant.

    Results
    The accumulative incidence of ≥ grade 2 clinical fibrosis and pneumonitis were 23.4%. The volume of lung measured by using CT or V and Q SPECT did not change significantly during radiotherapy (All p>0.05). The difference of lung volume between standard CT or V and Q SPECT was not significant in patients with RILT and without RILT (All p>0.05). However, the volume of V and Q both functional lung changed -12.4% (95% CI, -29.6% to 4.9%) in patients with RILT and 13.3% (95% CI, 2.7% to 23.9%) in patients without RILT during RT (p=0.02). The difference of mean lung dose (MLD) measured by using CT or V and Q SPECT was not significant in patients with RILT and without RILT (All p>0.05). However, the MLD was significantly higher in patients with RILT in during-RT than pre-RT CT (17.1 Gy and 15.4 Gy, p=0.01); the FMLD was significantly higher in patients with RILT in during-RT than pre-RT V and Q SPECT (16.7 Gy and 13.0 Gy, p=0.03). The V20-V55 by using during-RT CT were higher in the patients with RILT than without RILT (V20:29.0% and 22.0%, p=0.06; V25: 26.4 % and 19.0 % p=0.04; V30: 23.7 % and 16.6 %, p=0.03; V35: 21.1 % and 14.6 %, p=0.03; V40: 18.9 % and 12.6 %, p=0.02; V45: 16.4 % and 10.9 %, p=0.03; V50: 14.3 % and 9.1 % p=0.03; V55: 11.6 % and 7.5 %, p=0.04). The V5-V60 by using during-RT V and Q SPECT was higher in patients with RILT than without RILT, but not statistically significant.

    Conclusion
    Functional DVH metrics of V and Q SPECT and during-RT CT based DVH may be more significant in their association with RILT than pre-CT. However, these results need to be validated.