BACKGROUNDThe lung functional status could be displayed on lung perfusion images. With the images, the radiotherapy plans of lung cancer could be guided to more optimized. This study aimed to assess quantitatively the impact of incorporating functional lung imaging into 3-dimensional conformal radiotherapy (3DCRT) and intensity-modulated radiation therapy (IMRT) planning for non-small cell lung cancer (NSCLC).

METHODSTen patients with NSCLC who had undergone radiotherapy were included in this study. Before radiotherapy, each patient underwent CT simulation and lung perfusion imaging with single photon emission computed tomography (SPECT). The SPECT images were registered with simulation planning CT and used to contour functional lung (lung-F) and non-functional lung (lung-NF). Two 3DCRT plans and two IMRT plans were designed and compared in each patient: two anatomic plans using simulation CT alone and two functional plans using SPECT-CT in addition to the simulation CT. Dosimetric parameters of the four types of plans were compared in terms of tumor coverage and avoidance of normal tissues. Total radiation dose was set at 66 Gy (2 Gy x 33 fractions).

RESULTSIn incorporating perfusion information in 3DCRT and IMRT planning, the reductions on average in the mean doses to the functional lung in the functional plan were 168 cGy and 89 cGy, respectively, compared with those in the anatomic plans. The median reductions in the percentage of volume irradiated with > 5 Gy, > 10 Gy, > 20 Gy, > 30 Gy and > 40 Gy for functional lung in the functional plans were 6.50%, 10.21%, 14.02%, 22.30% and 23.46% in 3DCRT planning, respectively, and 3.05%, 15.52%, 14.16%, 4.87%, and 3.33% in IMRT planning, respectively. No greater degree of sparing of the functional lung was achieved in functional IMRT than in 3DCRT.

CONCLUSIONFunction-guided 3DCRT and IMRT plannings both appear to be effective in preserving functional lung in NSCLC patients.

Carcinoma, Non-Small-Cell Lung ; diagnostic imaging ; pathology ; radiotherapy ; Humans ; Radiography ; Radiotherapy, Conformal ; methods ; Radiotherapy, Intensity-Modulated ; methods ; Tomography, Emission-Computed, Single-Photon ; methods

BACKGROUNDHelical tomotherapy (HT) is a new image-guided intensity-modulated radiation therapy (IMRT) technique. It is reported that HT plan for non-small-cell lung cancer (NSCLC) can give better dose uniformity, dose gradients, and protection for the lung than IMRT plan. We compared the dosimetric characteristics of HT for NSCLC with those of conventional IMRT to observe the superiority of HT.

METHODSThere was a comparative case series comprising 10 patients with NSCLC. Computed tomographic (CT) images of delineated targets were transferred to the PrecisePlan planning system (IMRT) and Tomo planning system (HT). The prescription doses were 70 Gy/33F for the gross tumor volume (GTV) and the visible lymph nodes (GTVnd), and 60 Gy/33F for the clinical target volume (CTV) and the clinical target volume of the visible lymph nodes (CTVnd). The dose restrictions for organs at risk were as follows: the maximum dose to spinal cord ≤ 45 Gy, V20 to the total lungs < 30%, V50 to the heart < 50%, and V55 to the esophagus < 50%. Both plans were evaluated by means of the dose coverage of the targets, dose-volume histograms (DVHs), and other dosimetric indices.

RESULTSThe dose coverage, conformity, and homogeneity of the targets' volumes were found to be satisfactory in both plans, but the homogeneity of the HT plan was better than that of IMRT. The high-dose radiation volume (V20-V30) to the lung and the mean lung dose (MLD) decreased (P < 0.05), but the low-dose radiation volume (V5-V10) increased slightly in the HT plan (P > 0.05). The maximum doses to the spinal cord, heart, esophagus and trachea in the HT plan were lower than those in the IMRT plan, but the differences were not statistically significant.

CONCLUSIONSThe HT plan provids better dose uniformity, dose gradients, and protection for the organs at risk. It can reduce the high-dose radiation volume for lung and the MLD, but may deliver a larger lung volume of low-dose radiation.

Adult ; Aged ; Aged, 80 and over ; Carcinoma, Non-Small-Cell Lung ; diagnostic imaging ; radiotherapy ; Humans ; Male ; Middle Aged ; Radiography ; Radiotherapy Dosage ; Radiotherapy Planning, Computer-Assisted ; methods ; Radiotherapy, Intensity-Modulated ; methods ; Treatment Outcome

OBJECTIVE: To measure the intra-fraction displacements of the mediastinal metastatic lymph nodes by using four-dimensional CT (4D-CT) in non-small cell lung cancer (NSCLC). MATERIALS AND METHODS: Twenty-four patients with NSCLC, who were to be treated by using three dimensional conformal radiation therapy (3D-CRT), underwent a 4D-CT simulation during free breathing. The mediastinal metastatic lymph nodes were delineated on the CT images of 10 phases of the breath cycle. The lymph nodes were grouped as the upper, middle and lower mediastinal groups depending on the mediastinal regions. The displacements of the center of the lymph node in the left-right (LR), anterior-posterior (AP), and superior-inferior (SI) directions were measured. RESULTS: The mean displacements of the center of the mediastinal lymph node in the LR, AP, and SI directions were 2.24 mm, 1.87 mm, and 3.28 mm, respectively. There were statistically significant differences between the displacements in the SI and LR, and the SI and AP directions (p < 0.05). For the middle and lower mediastinal lymph nodes, the displacement difference between the AP and SI was statistically significant (p = 0.005; p = 0.015), while there was no significant difference between the LR and AP directions (p < 0.05). CONCLUSION: The metastatic mediastinal lymph node movements are different in the LR, AP, and SI directions in patients with NSCLC, particularly for the middle and lower mediastinal lymph nodes. The spatial non-uniform margins should be considered for the metastatic mediastinal lymph nodes in involved-field radiotherapy.
Adult ; Aged ; Aged, 80 and over ; Carcinoma, Non-Small-Cell Lung/*radiography/radiotherapy ; Contrast Media/diagnostic use ; Female ; Four-Dimensional Computed Tomography/*methods ; Humans ; Iohexol/analogs & derivatives/diagnostic use ; Lung Neoplasms/*radiography/radiotherapy ; Lymphatic Metastasis/*radiography ; Male ; Mediastinum/radiography ; Middle Aged ; Radiographic Image Interpretation, Computer-Assisted ; Statistics, Nonparametric