Measurement of intrafraction displacement of the mediastinal metastatic lymph nodes of non-small cell lung cancer based on four-dimensional computed tomography (4D-CT) / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To measure the intrafraction displacement of the mediastinal metastatic lymph nodes of non-small cell lung cancer (NSCLC) based on four-dimensional computed tomography (4D-CT), and to provide the basis for the internal margin of metastatic mediastinal lymph nodes.</p><p><b>METHODS</b>Twenty-four NSCLC patients with mediastinal metastatic lymph nodes confirmed by contrast enhanced CT (short axis diameter ≥ 1 cm) were included in this study. 4D-CT simulation was carried out during free breathing and 10 image sets were acquired. The mediastinal metastatic lymph nodes and the dome of ipsilateral diaphragma were separately delineated on the CT images of 10 phases of breath cycle, and the lymph nodes were grouped as the upper, middle and lower mediastinal groups depending on the mediastinal station. Then the displacements of the lymph nodes in the left-right, anterior-posterior, superior-inferior directions and the 3-dimensional vector were measured. The differences of displacement in three directions for the same group of metastatic lymph nodes and in the same direction for different groups of metastatic lymph nodes were compared. The correlation between the displacement of ipsilateral diaphragma and mediastinal lymph nodes was analyzed in superior-inferior direction.</p><p><b>RESULTS</b>The displacements in left-right, anterior-posterior and superior-inferior directions were (2.24 ± 1.55) mm, (1.87 ± 0.92) mm and (3.28 ± 2.59) mm for the total (53) mediastinal lymph nodes, respectively. The vectors were (4.70 ± 2.66) mm, (3.87 ± 2.45) mm, (4.97 ± 2.75) mm and (5.23 ± 2.67) mm for the total, upper, middle and lower mediastinal lymph nodes, respectively. For the upper mediastinal lymph nodes, the displacements in left-right, anterior-posterior and superior-inferior directions showed no significant difference between each other (P > 0.05). For the middle mediastinal lymph nodes, the displacements merely in anterior-posterior and superior-inferior directions showed significant difference (P = 0.005), while the displacements were not significantly different in the left-right and anterior-posterior, left-right and superior-inferior directions (P > 0.05). The displacements of the total and the lower mediastinal lymph nodes in left-right and superior-inferior, or anterior-posterior and superior-inferior directions were significantly different (P < 0.05), but was not significantly different in left-right and anterior-posterior directions (P > 0.05). The displacements of different group of mediastinal lymph nodes in a single direction or vector showed no significant difference (P > 0.05). In the superior-inferior direction, the correlation between the displacements of ipsilateral diaphragma and mediastinal lymph nodes were not statistically significant (P > 0.05).</p><p><b>CONCLUSIONS</b>During free breathing, the differences between the intrafractional displacement of mediastinal metastatic lymph nodes in the same direction and its station were not statistically significant. The displacements of the total mediastinal metastatic lymph nodes in the superior-inferior direction were greater than that in the left-right and anterior-posterior directions, especially for the middle and lower mediastinal metastatic lymph nodes. There was no significant correlation between the displacements of ipsilateral diaphragma and the mediastinal metastatic lymph nodes in the superior-inferior direction, so it was unreasonable to estimate and predict the displacement of mediastinal metastatic lymph nodes by the displacement of ipsilateral diaphragma.</p>

Evaluation of dosimetric variance in forward intensity modulated radiotherapy of the breast based on 4D CT and 3D CT during free breathing / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To explore the dosimetric variance in forward intensity modulated radiotherapy (IMRT) based on 4D CT and 3D CT after breast conserving surgery.</p><p><b>METHODS</b>Seventeen patients after breast conserving surgery underwent 3D CT simulation scans followed by respiration-synchronized 4D CT simulation scans at free breathing state. The treatment plan constructed using the end inspiration (EI) scan was then copied and applied to the end expiration (EE), and 3D scans and dose distribution were calculated separately. Dose-volume histograms (DVHs) parameters for the CTV, PTV, ipsilateral lung and heart were evaluated and compared.</p><p><b>RESULTS</b>The CTV volume difference was biggest between T0 and 3D CT, and the volume difference was 4.10 cm(3). Mean dose of PTV at EE was lower than that at EI (P = 0.019), but there were no statistically significant difference between 3D and EI, EE (all P > 0.05). The homogeneity index (HI) at EI, EE, 3D plans were 0.149, 0.159 and 0.164, respectively, and a significant difference was only between EI and EE (P = 0.039). The highest conformal index (CI) was at EI phase (P < 0.05), and there was no significant difference between EE and 3D (P = 0.758). The V(40) and V(50) of ipsilateral lung at EE phase were lower than that at EI (P < 0.05). There were no significant differences in all the indexes for heart (P > 0.05).</p><p><b>CONCLUSIONS</b>The breast deformation during respiration may be disregarded in whole breast IMRT. PTV dose distribution is significantly changed between EI and EE phases, and the differentiation of the lung high dose area between EI and EE phases may be induced by thorax expansion. 3D treatment planning is sufficient for whole breast forward IMRT, but 4D CT scans assisted by respiratory gating ensures more precise delivery of radiation dose.</p>

Protection of lung function by introducing single photon emission computed tomography lung perfusion image into radiotherapy plan of lung cancer / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>The 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).</p><p><b>METHODS</b>Ten 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).</p><p><b>RESULTS</b>In 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.</p><p><b>CONCLUSION</b>Function-guided 3DCRT and IMRT plannings both appear to be effective in preserving functional lung in NSCLC patients.</p>

FDG PET/CT versus PET alone for pre-surgical detection of lymph node metastasis in esophageal carcinoma / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To compare the combined FDG PET/CT with PET alone in the detection of lymph node metastasis (LNM) for esophageal carcinoma patient.</p><p><b>METHODS</b>From November 2003 to August 2005, 35 patients with esophageal carcinoma underwent FDG PET/CT before esophagectomy and lymph node (LN) dissection. The patients who had history of previous anticancer treatment or diabetes mellitus and inflammatory lung diseases as well as being inoperable for medical reasons were excluded. The results of LNM detection by PET/CT and PET alone were compared with pathological results.</p><p><b>RESULTS</b>Twenty-nine men and 6 women were eligible for this study, with a mean age of 57 years (range: 40 to 72 years). Of these 35 patients, 3 had lesion at the upper third thoracic esophagus, 22 at the middle third and 10 at the lower third. All patients underwent surgical resection successfully. Twenty-five patients and 65 out of 313 excised nodal groups were found to have metastases by pathological examination. The true positive and true negative LNM interpretation reached 61 and 229 LN groups on PET/CT versus 53 and 217 LN groups on PET alone. False negative LNM interpretation was found in 12 LN groups on PET alone, and 8 of them were corrected by PET/CT including one cervical LN, 4 paraesophageal LNs, one left gastric arterial LN, one left gastric cardia LN, one lesser gastric curve LN. False positive interpretations on PET alone were found in 31 LN groups, 12 of them were corrected by PET/CT which included 9 false-positive interpretations due to physical tracer uptake (2 in the cervical region and 7 in gastrointestinal tract ) and 3 lesions with heterogeneous tracer uptake in the primary tumor. The sensitivity, specificity and accuracy of LNM detection by PET alone was 81.54% (53/65), 87.50% (217/248), and 86.26% (270/313), whereas by PET/CT, which was 93.85% (61/65), 91.24% (229/248) and 92.65% (290/313), respectively. There were statistically significant differences in sensitivity and accuracy of LNM detection between PET/CT and PET alone (0.033 and 0.009).</p><p><b>CONCLUSION</b>Compared with FDG PET alone, FDG PET combined with CT can improve the sensitivity and accuracy in detection of lymph node metastasis in esophageal carcinoma.</p>

Impact of PET/CT on precise radiotherapy planning for non-small cell lung cancer / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To investigate the impact of PET/CT on the clinical staging, target volume delineation and precise radiotherapy (PAR) planning for patients with non-small cell lung cancer (NSCLC).</p><p><b>METHODS</b>PET/CT scanning was performed in 58 histologically proven NSCLC patients for radical radiotherapy or surgery. The clinical staging of all patients was determined by PET/CT according to 1997 World Health Organization (WHO) staging system. The gross tumor volume (GTV) was delineated and three-dimensional conformal radiotherapy (3D-CRT) planning was established with identical parameters based on CT image and PET/CT fused image, respectively. The indexes including volume of GTV (V(GTV)), percentage of the total lung volume which received more than 20 Gy (V(20)), mean lung dose (MLD), tumor control probability (TCP), normal tissue complication probability (NTCP), and dose to spinal cord (Ds) were selected and evaluated. The quality of the two plans and the impact of PET/CT on PAR planning was compare and analyzed.</p><p><b>RESULTS</b>1. PET/CT image results changed the clinical stages in 21 of 58 (36.2%) patients with 14 upstaged and 7 downstaged, therefore, the management decisions were modified in 16 (27.6%) patients. 2. Among 32 patients who underwent surgery, PET/CT staging result was consistent with pathologic staging in 29 with one false negative and 2 false positive in lymph node staging. The sensitivity of PET/CT was 96.9% and accuracy 90.6%. 3. The differences of indexes including V(GTV) (P = 0.004), V(20) (P = 0.000) and MLD (P = 0.004) between the two radiotherapy plannings were statistically significant, whereas, the Ds, TCP and NTCP (left lung, right lung, skin and spinal cord) was not.</p><p><b>CONCLUSION</b>1. The impact PET/CT on clinical staging of NSCLC and PAR planning was remarkable. 2. PET/CT is more consistent with pathology in staging than CT and, therefore, is an important compensatory staging measure. 3. Compared with CT, PET/CT can reduce the V(GTV) in patients with atelectasis and obstructive pneumonitis when contouring the target volume, so can provide better protection for normal surrounding lung tissue. On the other hand, PET/CT is more sensitive in detecting mediastinal lymph node metastasis than CT, and the V(GTV) can be more precise and guaranteed. 4. Radiopneumonitis may be more effectively prevented because of significant decrease in V(20) and MLD by more precise planning based on PET/CT results. 5. PET/CT not only can provide satisfactory Ds, TCP and NTCP within clinical demand, but also more precise delineation of the radiation target volume and precise radiotherapy planning for NSCLC.</p>