Objective To compare the accuracy of blood volume perfusion imaging (perfusion CT)with contrast enhanced 64-slice spiral computed tomography (CECT) in the evaluation of gross tumor volume (GTV) and clinical target volume (CTV) using rabbits with VX2 brain tumor. Methods Perfusion CT and CECT were performed in 20 rabbits with VX2 brain tumor. The GTV and CTV calculated with the maximal and minimal diameter of each tumor in the blood volume (BV) maps and CECT were measured and compared to those in pathological specimens. Results The mean value of the maximal and minimal diameter of GTV was (8.19 ± 2. 29) mm and (4.83 ± 1.31) mm in pathological specimens, (11.98 ±3.29) mmand (7.03±1.82) mm in BV maps, while (6.36±3.85) mm and (3.17±1.93) mm in CECT images, which were significantly different (pathological specimen vs. BV map, t = 7. 17,P =0. 000;pathological specimen vs. CECT, t = 8.37, P = 0. 000, respectively). The mean value of the maximal and minimal diameter of CTV in pathologic specimens was (12.87 ± 3.74) mm and (7.71 ± 2. 15) mm, which was significantly different from that of GTV and CTV in CECT (t = - 3. 18, P = 0. 005 and t = - 4. 24, P =0. 000;t= -11.59,P=0.000 and t= -9.39,P=0.000), while similar with that of GTV in BV maps (t = - 1.95,P = 0. 067; t = - 2. 06, P = 0. 054). For CECT, the margin from GTV to CTV was 81.83% ±40.33% for the maximal diameter and 276.73% ± 131.46% for the minimal. While for BV maps, the margin was 7.93% ± 17. 84% and 12.52% ± 27. 83%, which was significant different from that for CECT images (t=7.36,P=0. 000 and t= -8.78,P=0.000). Conclusions Compared with CECT, the BV map from 64-slice spiral CT peffusion imaging might have higher accuracy in target volume delineation for brain tumor.

Radiotherapy is one of the most important treatments of malignant tumors. However, after the radiotherapy combined with surgery and systemic therapy significantly improved the prognosis of cancer patients, somelong-term survivors after radiation exposure were diagnosed as second primary malignancies such as breast cancer, esophageal cancer, rectal cancer, bladder cancer, and sarcoma. This paper mainly discusses the radiotherapy-induced second primary neoplasms in terms of the dose-effect relationship, incubation period, influencing factors, diagnosis, treatment, and prognosis.