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. Author manuscript; available in PMC: 2012 May 14.
Published in final edited form as: J Thorac Oncol. 2011 Jan;6(1):71–78. doi: 10.1097/JTO.0b013e3181f77b40

Table 3.

Pulmonary V/Q relationship and potential application on RT planning

V/Q defect relationship Potential etiology (CT based findings) Activity degree Application types in guiding RT No of patients (%)
V Q Q SPECT V/Q SPECT
Matched 31 (61%)
Mass effect 0 0 A A 19
Hilar mass compression to both large vessels & airway 0 0 B3 B3 3
Collapsed lung 0 0 B3 B3 2
Stage I-II COPD 1 1 B2 B2 4
Stage III COPD 1 1 B2 B2 2
Interstitial lung disease 1 1 B2 B2 1
Reverse mismatched 16 (31%)
Tumor induced endobronchial obstruction 0 1 C B3 9
Stage III-IV COPD 0 1 B2 B1 7
Mismatched 4 (8%)
Tumor induced extrinsic compression of the pulmonary artery or its branches 2 0 B3 C 4

(1) Abbreviation: V=ventilation; Q=perfusion; RT=radiotherapy; COPD=chronic obstructive pulmonary disease.

(2) According to V/Q SPECT imaging intensity, the activity degree of pulmonary ventilation, perfusion defect was defined, respectively, as 0 if activity absent (virtually invisible), 1 if activity reduced, but still visible, 2 if activity in normal lung range. The potential etiologies of V/Q defects were determined based on CT findings, PET/CT findings and other clinical data.

(3) Functional imaging application types in guiding RT
  • Type A regions: functional defects corresponding to the location of tumor. These “bad” tumor occupying lung regions, should be given as high RT dose as possible;
  • Type B1 regions: complete function defect induced by COPD or other unrecoverable diseases. These regions, with unrecoverable non-functioning “bad” lung, can be given high dose RT without causing change in the global lung function.
  • Type B2 regions: reduced lung function induced by COPD or other unrecoverable diseases. These regions, with unrecoverable low functioning lung, may be given high dose (if no worse lung available) without causing remarkable change in the global lung function.
  • Type B3 regions: temporarily dysfunctional lung induced by tumor and other potentially recoverable diseases. These regions could be “good”, if they improve during treatment, and would then be minimized for further RT or high dose RT; may be “bad”, if there is no improvement during treatment, can be given high dose as indicated.
  • Type C regions: normal functioning “good” lung. The RT dose to such regions should be minimized to decrease functional or clinically significant sequalae.