Reduction in stray radiation dose using a body-shielding device during external radiation therapy.

With the purpose of reducing stray radiation dose (SRD) in out-of-field region (OFR) during radiotherapy with 6 MV intensity-modulated radiation therapy (IMRT), a body-shielding device (BSD) was prepared according to the measurements obtained in experimental testing. In experimental testing, optimal shielding conditions, such as 1 mm lead, 2 mm lead, and 1 mm lead plus 10 mm bolus, were investigated along the medial axis of a phantom using thermoluminescent dosimeters (TLDs). The SRDs at distances from field edge were then measured and analyzed for a clinical IMRT treatment plan for nasopharyngeal carcinoma before and after shielding using the BSD. In addition, SRDs in anterior, posterior, left and right directions of phantom were investigated with and without shielding, respectively. Also, the SRD at the bottom of treatment couch was measured. SRD decreased exponentially to a constant value with increasing distance from field edge. The shielding rate was 50%-80%; however, there were no significant differences in SRDs when shielded by 1 mm lead, 2 mm lead, or 1 mm lead plus 10 mm bolus (P>0.05). Importantly, the 10 mm bolus absorbed back-scattering radiation due to the interaction between photons and lead. As a result, 1 mm lead plus 10 mm bolus was selected to prepare the BSD. After shielding with BSD, total SRDs in the OFR decreased to almost 50% of those without shielding when irradiated with IMRT beams. Due to the effects of treatment couch and gantry angle, SRDs at distances were not identical in anterior, posterior, left and right direction of phantom without BSD. As higher dose in anterior and lower dose in posterior, SRDs were substantial similarities after shielding. There was no significant difference in SRDs for left and right directions with or without shielding. Interestingly, SRDs in the four directions were similar after shielding. From these results, the BSD developed in this study may significantly reduce SRD in the OFR during radiotherapy, thus decreasing the risk of secondary cancers.

Analysis of setup error based on CTVision for nasopharyngeal carcinoma during IGRT.

The aim of the present study was to investigate the role of CTVision in interfractional setup errors during intensity-modulated radiation therapy (IMRT) in 12 nasopharyngeal carcinoma (NPC) patients. The trend of setup errors as a function of time during a fractionated radiotherapy course was investigated, and the influence of reconstructive thickness on image reconstruction for setup errors was analyzed. The appropriate planning target volume (PTV) margin and planning risk volume (PRV) margin were defined to provide a reference for the design of IMRT for NPC. Based on CTVision, online CT was performed weekly for each patient. Setup errors were measured by registration between the CT reconstructed image and reference image. Mean of setup errors, estimated population systematic (Σ), and population random (σ) errors were calculated using SPSS (v15.0). Optimum PTV and PRV margins were calculated. In the clinical data, for the LR (left-right), SI (superior-inferior), and AP (anterior-posterior) directions, Σ was 0.8, 0.8, and 1.0 mm, respectively, and σ was 1.0, 1.3, and 0.8 mm, respectively. In the LR, SI, and AP directions, PTV margins were at least 2.7, 2.9, and 3.0 mm, respectively, and PRV margins were at least 1.5, 1.7, and 1.7 mm, respectively. No significant differences in setup errors were observed during the fractionated radiotherapy course (p > 0.05). However, CT image reconstruction with different thicknesses affected the accuracy of measurements for setup errors, particularly in the SI direction. The application of CTVision to correct setup errors is important and can provide reasonable margins to guarantee the coverage of PTVs and spare organs at risk. A thickness of 3 mm in the reconstructed image is appropriate for the measurement of setup errors by image registration.

Lack of association between the GRP78 polymorphisms in the promoter and 3' UTR and susceptibility to chronic HBV infection in a Chinese Han population.

BACKGROUND: Hepatitis B virus (HBV) infection causes large amount of unfolding or false-folding protein accumulation in the endoplasmic reticulum (ER), which in turn induces the expression of glucose-regulated protein 78 (GRP78). The aim in the present study was to analyse the potential association between GRP78 single-nucleotide polymorphisms (SNPs) and the risk of HBV infection. METHODS: The associations between seven common GRP78 polymorphisms in the promoter (rs391957, rs17840762, rs17840761, rs11355458) and in the 3' untranslated region (UTR) (rs16927997, rs1140763, rs12009) and possible risk of chronic HBV infection were assessed in a case-control study. 496 cases and 539 individually matched healthy controls were genotyped. RESULTS: Overall, no associations were observed in genotypic analyses. In addition, haplotypes and diplotypes combining those SNPs in the promoter or in the 3' UTR in high linkage disequilibrium (LD) were also not associated with HBV risk. CONCLUSION: These observations do not support a role for GRP78 polymorphisms in HBV infection in a predominantly Chinese Han population.

[Comparison of the irradiation doses for IMRT and conventional radiotherapy in nasopharyngeal carcinoma patients].

OBJECTIVE: To compare the dose difference in irradiation dose between nasopharyngeal cancer patients receiving conventional radiotherapy (CR) and intensity-modulated radiotherapy (IMRT). METHODS: The various IMRT and the CR plans for patients with nasopharyngeal carcinoma were created by a three-dimensional treatment planning system (3D-TPS). The dose-volume histograms (DVH) of normal tissues and the total number of irradiation monitor units (MU) were calculated by 3D-TPS. The treatment was delivered with 6 MV photons using a "step-and-shoot" technique on a linear accelerator. The X-ray leakage and scattered dose (LSD) at the dmax (maximal dose depth) in water were measured by dosimeter and ion chamber. The dose delivered to normal tissue adjacent to the treatment site at a certain distance was estimated by using LSD and the total MU for different radiotherapy methods. RESULTS: To IMRT patients, the volumes of normal tissues receiving the dose less than 28 Gy and higher than 35 Gy were 1.43-1.81 and 0.70-0.30 times those of CR patients respectively. The LSD irradiated that to the IMRT patients was about two times of the CR patients. CONCLUSION: The dose received by normal tissues in IMRT is two times that in CR.

[Radiofrequency thermal ablation combined with arterial embolization for primary liver cancer].

OBJECTIVE: To explore the short-term effect of radiofrequency ablation (RFA) combined with arterial embolization in treating patients with primary liver cancer. METHODS: Thirty patients with primary liver cancer received the combined treatment and the pre- and post-operative alpha-fetoprotein (AFP) levels, imaging features, and liver function were investigated along with observation of the incidence of complications to evaluate the therapeutic effects. RESULTS: The post-operative AFP positivity and the tumor density were significantly reduced in these patients, and their one-year survival rate reached 96.7% with only minor complications observed. CONCLUSION: RFA combined with arterial embolization is effective for primary liver cancer.

Optimal beam arrangement for pulmonary ventilation image-guided intensity-modulated radiotherapy for lung cancer.

BACKGROUND: The principal aim of this study was to evaluate the feasibility of incorporating four-dimensional (4D)-computed tomography (CT)-based functional information into treatment planning and to evaluate the potential benefits of individualized beam setups to better protect lung functionality in patients with non-small cell lung cancer (NSCLC). METHODS: Peak-exhale and peak-inhale CT scans were carried out in 16 patients with NSCLC treated with intensity-modulated radiotherapy (IMRT). 4D-CT-based ventilation information was generated from the two sets of CT images using deformable image registration. Four kinds of IMRT plans were generated for each patient: two anatomic plans without incorporation of ventilation information, and two functional plans with ventilation information, using either five equally spaced beams (FESB) or five manually optimized beams (FMOB). The dosimetric parameters of the plans were compared in terms of target and normal tissue structures, with special focus on dose delivered to total lung and functional lung. RESULTS: In both the anatomic and functional plans, the percentages of both the functional and total lung regions irradiated at V5, V10, and V20 (percentage volume irradiated to >5, >10 and >20 Gy, respectively) were significantly lower for FMOB compared with FESB (P < 0.05), but there was no significant difference for V30 (P > 0.05). Compared with FESB, a greater degree of sparing of the functional lung was achieved in functional IMRT plans with optimal beam arrangement, without compromising target volume coverage or the irradiated volume of organs at risk, such as the spinal cord, esophagus, and heart. CONCLUSIONS: Pulmonary ventilation image-guided IMRT planning with further optimization of beam arrangements improves the preservation of functional lung in patients with NSCLC.

4D-CT reconstruction based on pulmonary average CT values.

To date, commercial 4D-CT systems typically depend on an external respiratory monitoring device. Immobilizing patients in a thermoplastic mask while receiving radiotherapy may result in a failure of 4D-CT reconstruction. The aim of this study is to investigate the feasibility of 4D-CT reconstruction based on a method using pulmonary average CT values (ACV) without an external respiratory monitoring device. The ACV of the whole lung assumes cyclical variation during respiration. Phases of CT images were identified by calculating the ACV over time. Subsequently, five sets of 4D-CT images based on a Real-time Position Management (RPM) system were selected to verify the ACV method. The entire lung CT datasets of another sixteen free-breathing patients were acquired in Cine scan mode for multiple couch positions. The phase of every CT image was identified and re-sorted into different phase 4D-CT volumes by analyzing the time dependence of the corresponding ACVs. This paper demonstrates the ACV method using the 4D-CT data sets based on the RPM system. Convenient and reliable 4D-CT reconstruction can be accomplished without any external respiratory monitoring device using ACVs.

Volume and dosimetric variations during two-phase adaptive intensity-modulated radiotherapy for locally advanced nasopharyngeal carcinoma.

The aims of this study were to evaluate the volume and dosimetric variations during IMRT for locally advanced NPC and to identify the benefits of a two-phase adaptive IMRT method. Twenty patients with locally advanced NPC having received IMRT treatment were included. Each patient had both an initial planning CT (CT-1) and a repeated CT scan (CT-2) after treatment at a dose of 40 Gy. Three IMRT planning scenarios were compared: (1) the initial plan on the CT-1 (plan-1); (2) the hybrid plan recalculated the initial plan on the CT-2 (plan-2); (3) the replan generated on the CT-2 being used to complete the course of IMRT (plan-3). The mean gross target volume and mean volumes of the positive neck lymph nodes, high-risk clinical target volume, and the left and right parotid glands significantly decreased by 30.2%, 45.1%, 21.1%, 14.7% and 18.2%, respectively on the CT-2. Comparing plan-2 with plan-1, the dose coverage of the targets remained unchanged, whereas the dose delivered to the parotid glands and spinal cord increased significantly. These patients with locally advanced NPC might benefit from replanning because of the sparing of the parotid glands and spinal cord.

Resection of a giant hepatocellular carcinoma weighing over ten kilograms.

The authors report a giant hepatocellular carcinoma (HCC) with a diameter over 30 cm and weight over 10 kg that was resected completely. A 62-year-old man was admitted because of continuous abdominal uplift. A computed tomography scan demonstrated that the entire abdomen was filled with a giant tumor containing both cystic and solid components with a size of 29 cm x 22 cm. The huge tumor was successfully resected without any complication, such as massive hemorrhage or visceral injuries. The size and weight of the tumor were 35 cm x 30 cm x 15 cm and 10 050 g, respectively. Pathological examination showed that the tumor was a well-differentiated HCC, and alpha-fetoprotein was positive. Postoperative syndrome, characterized by hypovolemic shock, diarrhea and urine retention, was observed and induced by abdominal decompression. This syndrome was resolved with expectant treatment. The patient was still alive without recurrence after a 27-mo follow-up.

Chemotherapy with laparoscope-assisted continuous circulatory hyperthermic intraperitoneal perfusion for malignant ascites.

AIM: To investigate the procedure, feasibility and effects of laparoscope-assisted continuous circulatory hyperthermic intraperitoneal perfusion chemotherapy (CHIPC) in treatment of malignant ascites induced by peritoneal carcinomatosis from gastric cancers. METHODS: From August 2006 to March 2008, the laparoscopic approach was used to perform CHIPC on 16 patients with malignant ascites induced by gastric cancer or postoperative intraperitoneal seeding. Each patient underwent CHIPC three times after laparoscope-assisted perfusion catheters placing. The first session was completed in operative room under general anesthesia, 5% glucose solution was selected as perfusion liquid, and 1500 mg 5-fluorouracil (5-FU) and 200 mg oxaliplatin were added in the perfusion solution. The second and third sessions were performed in intensive care unit, 0.9% sodium chloride solution was selected as perfusion liquid, and 1500 mg 5-FU was added in the perfusion solution alone. CHIPC was performed for 90 min at a velocity of 450-600 mL/min and an inflow temperature of 43 +/- 0.2 degrees C. RESULTS: The intraoperative course was uneventful in all cases, and the mean operative period for laparoscope-assisted perfusion catheters placing was 80 min for each case. No postoperative deaths or complications related to laparoscope-assisted CHIPC occurred in this study. Clinically complete remission of ascites and related symptoms were achieved in 14 patients, and partial remission was achieved in 2 patients. During the follow-up, 13 patients died 2-9 mo after CHIPC, with a median survival time of 5 mo. Two patients with partial remission suffered from port site seeding and tumor metastasis,and died 2 and 3 mo after treatment. Three patients who are still alive today survived 4, 6 and 7 mo, respectively. The Karnofsky marks of patients (50-90) increased significantly (P < 0.01) and the general status improved after CHIPC. Thus satisfactory clinical efficacy has been achieved in these patients treated by laparoscopic CHIPC. CONCLUSION: Laparoscope-assisted CHIPC is a safe, feasible and effective procedure in the treatment of debilitating malignant ascites induced by unresectable gastric cancers.

Up-regulation of PIK3CA promotes metastasis in gastric carcinoma.

AIM: To explore expressions of PIK3CA in the progression of gastric cancer from primary to metastasis and its effects on activation of phosphatidylinositol 3-kinase (PI3K)/Akt pathway. METHODS: mRNA and protein levels of PIK3CA were assessed, respectively, by real-time quantitative polymerase chain reaction and immunohistochemistry in specimens of normal gastric mucosa, primary foci and lymph node and distant metastasis of gastric cancer. Akt and phosphorylated Akt protein were also examined by Western blotting in these tissues, in order to analyze the effect of PIK3CA expression level changes on the activation of PI3K/Akt signaling pathway. RESULTS: PIK3CA mRNA in lymph node metastasis were approximately 5 and 2 folds higher, respectively, than that in the corresponding normal gastric mucosa and primary gastric cancer tissues (P < 0.05), while no statistical significance was found compared with distant metastasis. Immunohistochemically, PIK3CA protein expression was discovered in 7 (35%) specimens of 20 primary foci vs 10 (67%) of 15 of lymph node metastasis or 11 (61%) of 18 of distant metastasis (35% vs 67%, P = 0.015; 35% vs 61%, P = 0.044). With the increased level of PIK3CA expression, the total Akt protein expression remained almost unchanged, but p-Akt protein was upregulated markedly. CONCLUSION: Increased expression of PIK3CA is expected to be a promising indicator of metastasis in gastric cancer. Up-regulation of PIK3CA may promote the metastasis of gastric cancer through aberrant activation of PI3K/Akt signaling.