OBJECTIVETo evaluate the effects of a solitary megadose protocol of ionizing radiation (IR) to parotid gland on the structured and function changes of bilateral parotid glands in miniature pig.

METHODSFourteen minipigs were subjected to either 15 or 20 Gy to one parotid gland with a linear accelerator, while another four minipigs served as non-IR controls. Salivary flow rates and salivary chemistries were measured pre-IR, and 4 and 16 weeks post-IR. A quantitative assessment of gland weight and acinar area, and detailed serum chemistry and hematological analyses, were also performed.

RESULTSParotid gland weights were significantly decreased in the 15 and 20 Gy groups at 4 and 16 weeks post-IR. The acinar cell area in glands of both IR groups was significantly reduced. Parotid flow rates decreased by 60% with 15 Gy at 16 weeks post-IR. In the 20 Gy group, salivary flow rates were reduced by 80% at 16 weeks post-IR. Additionally, parotid flow rates significantly reduced in contralateral glands with 20 Gy at 16 weeks, while structure and weight did not changes in parotid glands.

CONCLUSIONStructural changes in salivary gland parenchyma occurred relatively early after IR, while the alterations in salivary output were relatively delayed. Further, reductions in salivary flow were not proportional to acinar cell area loss. There isn't a significant structured change of contralateral glands, but significant reduction of parotid flow rate at this time.

Animals ; Parotid Gland ; radiation effects ; Swine ; Swine, Miniature

AIMTo evaluate the effect of single or dual field irradiation (IR) with the same dose on damage to miniature pig parotid glands.

METHODOLOGYSixteen miniature pigs were divided into two IR groups (n=6) and a control group (n=4). The irradiation groups were subjected to 20 Gy X-radiation to one parotid gland using single-field or dual-field modality by linear accelerator. The dose-volume distributions between two IR groups were compared. Saliva from parotid glands and blood were collected at 0, 4, 8 and 16 weeks after irradiation. Parotid glands were removed at 16 weeks to evaluate tissue morphology.

RESULTSThe irradiation dose volume distributions were significantly different between single and dual field irradiation groups (t=4.177, P=0.002), although dose volume histogramin (DVH) indicated the equal maximal dose in parotid glands. Saliva flow rates from IR side decreased dramatically at all time points in IR groups, especially in dual field irradiation group. The radiation caused changes of white blood cell count in blood, lactate dehydrogenase and amylase in serum, calcium, potassium and amylase in saliva. Morphologically, more severe radiation damage was found in irradiated parotid glands from dual field irradiation group than that from single field irradiation group.

CONCLUSIONData from this large animal model demonstrated that the radiation damage from the dual field irradiation was more severe than that of the single field irradiation at the same dose, suggesting that dose-volume distribution is an important factor in evaluation of the radiobiology of parotid glands.

Amylases ; analysis ; blood ; radiation effects ; Animals ; Blood Platelets ; radiation effects ; Calcium ; analysis ; radiation effects ; Erythrocyte Count ; Erythrocytes ; radiation effects ; L-Lactate Dehydrogenase ; blood ; radiation effects ; Leukocyte Count ; Leukocytes ; radiation effects ; Male ; Models, Animal ; Organ Size ; radiation effects ; Parotid Gland ; pathology ; radiation effects ; Potassium ; analysis ; radiation effects ; Radiation Dosage ; Random Allocation ; Saliva ; chemistry ; radiation effects ; Secretory Rate ; radiation effects ; Swine ; Swine, Miniature ; Time Factors

OBJECTIVETo evaluate the dynamic change of salivary gland function in patients with nasopharyngeal carcinoma (NPC) before and after intensity modulated radiotherapy (IMRT) by DWMRI.

METHODSTwenty-three NPC patients confirmed by pathology were enrolled. Male/Female: 19/4. The age was from 37 to 69 years. All cases underwent salivary glands examination by DWMRI before IMRT, at the end of IMRT, 6 months and 12 months after IMRT, at the same time the ADC value of salivary glands were calculated. The patients were divided into two groups: G1, Dmean < 26 Gy, G2, Dmean ≥ 26 Gy. SPSS 13.0 and SAS 8.2 software was used to analyze the date.

RESULTSThe ADC values of parotid in two group patients at rest were not significantly different between 6 months after and at the end of IMRT (t value was 0.732, 1.405, all P > 0.05). The ADC values of parotid in two group patients at rest were significantly lower in the 12 months after IMRT than at the end of IMRT (t value 2.621, 3.417, all P < 0.05). During the period of acid stimulation, A significant change of ADC in parotid was found in G1 (all P < 0.05) and no significant change of ADC in parotid was found in G2 at the various follow-up time after IMRT (all P > 0.05). At the various follow-up time after IMRT, the average ADC values of parotid were significantly higher in G2 than G1 in the same time points of acid stimulation (all P < 0.05). The ADC values of submandibular glands at rest were significantly higher at the various follow-up time after IMRT than before IMRT (t value was -9.782, -8.963, -7.722, all P < 0.05). During the period of acid stimulation no significant change of ADC in submandibular glands was found after IMRT (F = 1.124, P = -0.348).

CONCLUSIONSThe changes of salivary function can be well reflected by ADC values. There is a good clinical application value of DWMRI for evaluating radiation-induced salivary glands functional changes and observing salivary function recovery during the follow-up period after IMRT.

Adult ; Aged ; Carcinoma ; Diffusion Magnetic Resonance Imaging ; Female ; Humans ; Male ; Middle Aged ; Nasopharyngeal Neoplasms ; radiotherapy ; Parotid Gland ; radiation effects ; Radiotherapy Dosage ; Radiotherapy, Intensity-Modulated ; Recovery of Function ; Salivary Glands ; radiation effects ; Submandibular Gland ; radiation effects

OBJECTIVETo investigate the effect of Sarcandra glabra in scavenging reactive oxygen species (ROS) produced by γ-ray irradiation in the parotid gland of miniature pigs.

METHODSForty-five male miniature pigs were randomly divided into control group, radiation group and radiation plus medication group, and each group contained 3 parallel groups (subgroups a, b and c). From 1 week before exposure of the parotid gland region to 15 Gy γ-ray irradiation (which was not administered in the control group), the miniature pigs in radiation plus medication group were given Sarcandra glabra powder, while those in the other groups received an equal amount of saline. Bilateral parotid glands were taken and weighed on the days 10, 40 and 90 following the exposure in subgroups a, b, and c, respectively, and ROS content in the parotid glands were determined by enzyme-linked immunosorbent assay.

RESULTSThe content of ROS was significantly lower in radiation plus medication group than in the radiation group (P<0.01). In the radiation plus medication group, the ROS content showed no significant difference between subgroups a and b or between subgroups a and c (P>0.01), but differed significantly between subgroups b and c (P<0.01). Sarcandra glabra showed a strong ROS-scavenging effect 10 days after the irradiation, and the ROS content was similar with that in the control group (P>0.01); at 40 and 90 days, the ROS-scavenging effect of Sarcandra glabra was still observable, but the ROS content was significantly higher in the irradiation plus medication group than in the control group (P<0.01).

CONCLUSIONSarcandra glabra displays a ROS-scavenging effect in the parotid gland of miniature pigs against irradiation, especially at 10 days following the exposure, which may serve as the main mechanism for the protective effect of Sarcandra glabra against radiation injury in the parotid gland.

Animals ; Drugs, Chinese Herbal ; pharmacology ; Free Radical Scavengers ; pharmacology ; Magnoliopsida ; chemistry ; Male ; Parotid Gland ; metabolism ; radiation effects ; Radiation Injuries ; prevention & control ; Radiation-Protective Agents ; pharmacology ; Reactive Oxygen Species ; metabolism ; Swine ; Swine, Miniature

The intensity-modulated radiation therapy (IMRT) planning strategies for nasopharyngeal cancer among Korean radiation oncology facilities were investigated. Five institutions with IMRT planning capacity using the same planning system were invited to participate in this study. The institutions were requested to produce the best plan possible for 2 cases that would deliver 70 Gy to the planning target volume of gross tumor (PTV1), 59.4 Gy to the PTV2, and 51.5 Gy to the PTV3 in which elective irradiation was required. The advised fractionation number was 33. The planning parameters, resultant dose distributions, and biological indices were compared. We found 2-3-fold variations in the volume of treatment targets. Similar degree of variation was found in the delineation of normal tissue. The physician-related factors in IMRT planning had more influence on the plan quality. The inhomogeneity index of PTV dose ranged from 4 to 49% in Case 1, and from 5 to 46% in Case 2. Variation in tumor control probabilities for the primary lesion and involved LNs was less marked. Normal tissue complication probabilities for parotid glands and skin showed marked variation. Results from this study suggest that greater efforts in providing training and continuing education in terms of IMRT planning parameters usually set by physician are necessary for the successful implementation of IMRT.
Female ; Humans ; Male ; Middle Aged ; Nasopharyngeal Neoplasms/*radiotherapy ; Parotid Gland/radiation effects ; Radiotherapy Dosage ; Radiotherapy Planning, Computer-Assisted/*methods ; Radiotherapy, Intensity-Modulated/*methods ; Relative Biological Effectiveness ; Skin/radiation effects ; Tumor Burden ; Young Adult

OBJECTIVETo evaluate the radiation induced parotid dysfunction in nasopharyngeal carcinoma (NPC) patients who had received different methods of radiotherapy.

METHODSFrom January 1996 to January 2000, 380 NPC patients were divided into conventional fraction (CF-175 patients), late-course accelerated hyperfractionation (LCAF-63 patients) and intensity modulated radiation therapy (IMRT-142 patients) groups. Conventional radiotherapy was given with a total dose of 70 Gy. Patients in the LCAF group were treated with the same fractionation as CF group until the dose of 36 - 40 Gy, then followed by LCAF radiotherapy to a total dose of 75 Gy. IMRT in the form of full-course was given to a total dose of 72 Gy. Acute parotiditis was observed during the treatment. The parotid secretory function was examined 2 years after radiotherapy.

RESULTSThe dose of parotid in IMRT was much lower than those in the other 2 groups. Extreme damage rates of parotid secretory function in CF, LCAF and IMRT groups were 81.7%, 81.0% and 69.7% (P < 0.05); acute parotiditis rates were 23.4%, 20.4% and 41.3% respectively, with the differences among the 3 groups significant (P < 0.05).

CONCLUSIONThe radiation parotid functional damage differs in the various methods of radiotherapy. IMRT, being able to improve the tumor target coverage and spare the adjacent critical structures, is indicated for NPC.

Adolescent ; Adult ; Carcinoma, Squamous Cell ; radiotherapy ; Dose Fractionation ; Female ; Humans ; Male ; Middle Aged ; Nasopharyngeal Neoplasms ; radiotherapy ; Parotid Gland ; physiopathology ; radiation effects ; Parotitis ; etiology ; Radiation Injuries ; physiopathology ; Radiotherapy, Intensity-Modulated ; methods