Konstantinos Dardoufas

A pilot study of the effect of granulocyte–macrophage colony–stimulating factor on oral mucositis in head and neck cancer patients during x-radiation therapy: a preliminary report

PURPOSE To evaluate the effect of granulocyte-macrophage colony-stimulating factor (GM-CSF) in reduction of radiotherapy-induced oral mucositis. METHODS AND MATERIALS Seventeen patients who were going to be irradiated with a total dose of 50-70 Gy for head and neck malignancies were included in the study. After the second week of radiotherapy, with the experience of oral pain, GM-CSF 400 microg was administered locally, once a day, until completion of radiotherapy. Patients were evaluated weekly for mucosal reaction and functional impairment. RESULTS Three patients with gross and functional mucositis grade I after the second week, completed the planned radiotherapy showing mucositis grade I. Eleven patients who experienced, after 2 weeks of radiotherapy, mucositis grade II and III, presented after the third week with gross mucositis grade I and II and functional impairment grade I. One of these 11 patients was then lost to follow-up and the remaining 10 completed their planned radiotherapy having an almost asymptomatic mucositis grade I. The 15th patient with gross mucositis grade III after the 2 weeks of radiotherapy, had a 2-day interruption because of painful mucositis and then continued and completed radiotherapy with gross and functional mucositis grade I. The 16th patient with mucositis grade III after the second week, did not show any improvement, and completed her planned radiotherapy with mucositis grade III which finally healed after the administration of acyclovir. The last, 17th patient discontinued radiotherapy at the third week because of mucositis grade IV and severe ulceration in apposition to an extensive gold prosthesis. CONCLUSION The local administration of GM-CSF significantly reduced and almost healed radiation-induced oral mucositis in 14 of 17 patients during the radiotherapy, which was completed within the preplanned time and without any significant patient weight loss or functional impairment.

A Monte Carlo investigation of the dosimetric characteristics of the VariSource 192Ir high dose rate brachytherapy source.

An analytical Monte Carlo simulation code, incorporating in detail source construction and dimensions, was used to investigate the dosimetric characteristics of the VariSource 192Ir high dose rate brachytherapy source. Dose-rate constant, radial dose functions, and anisotropy functions, utilized in the AAPM Task Group 43 dose estimation formalism, were calculated with the source centered in a spherical water phantom of 30 cm in diameter. The results, which are in agreement with the corresponding data available in the literature, are compared to those obtained in our previous study for the widely used microSelectron 192Ir high dose-rate brachytherapy source. The dose-rate constant was found to be equal to 1.043 +/- 0.005 cGy h(-1) U(-1) for the VariSource, compared to a value of 1.116 +/- 0.006 cGy h(-1) U(-1) calculated for the microSelectron. Significant differences in the anisotropy of the two sources are observed only for polar angles close to their long axis and are due to their different dimensions.

Oral candidiasis in head and neck cancer patients receiving radiotherapy with amifostine cytoprotection

This controlled study assessed the incidence of oral candidiasis, a xerostomia-related complication, in head and neck cancer patients receiving radiotherapy, with amifostine cytoprotection. Thirty-eight patients received 500 mg amifostine i.v., prior to each radiotherapy fraction, while 16 patients received radiotherapy alone. Oral candidiasis was diagnosed according to the criteria described before. Subjective xerostomia scales were completed by all patients. Mucositis was evaluated using the RTOG criteria. Oral candidiasis was diagnosed in 11/38 amifostine patients and in 9/16 controls (P = 0.07). Severe xerostomia was reported by 4/38 amifostine patients and by 7/16 controls. Oral candidiasis was reduced with amifostine cytoprotection. Oral candidiasis is suggested as an objective, early, though indirect, endpoint for amifostines radioprotective effect on salivary glands.

Oral Mucositis, Pain and Xerostomia in 135 Head and Neck Cancer Patients Receiving Radiotherapy with or without Chemotherapy

Goal of work: This study compared the severity of oral mucositis, pain and xerostomia during and at the completion of radiotherapy in head and neck cancer patients who had received antifungal and antiviral treatment. Patients: The study included 135 patients. Mean total radiotherapy dose was 62.4 Gray. Chemotherapy was administered to 47% of patients. Methods: Oral mucositis was scored weekly, while patients self-evaluated their pain and xerostomia. Cytology smears for the assessment of herpetic infection complicating the ulcers of mucositis were taken from 46 patients. Systemic antifungals and antivirals were administered during radiotherapy, upon clinical, presumptive diagnosis of candidiasis and herpetic infection. Antifungals and antivirals were continued to the end of radiotherapy. Results: Radiotherapy was completed within the preplanned time in 117 patients (87%). During radiotherapy, the prevalence of severe mucositis, pain and xerostomia was 57%, 43% and 29% respectively, and was significantly reduced to 33%, (P<0.001), to 24%, (P<0.001), and to 18%, (P<0.05) at the end of radiotherapy. Antifungals and antivirals were utilized in 70% and 71% of patients, respectively. Viral cytology was positive in 14 of 46 (30.4%) patients. Conclusions: The significant reduction of severe oral mucositis, pain and xerostomia at time of completion of radiotherapy, as compared to during the course of radiotherapy, after the treatment and prevention of candidiasis and herpes, denotes an important role of these infections in radiation-induced mucositis. Limitations of the study are the practical issues of the lack of the verification of the fungal status before and after treatment and of the verification of the viral status in only 47.9% (46 of 96) of the patients with a clinical suspicion of herpetic infection. A controlled study is needed to investigate and further clarify the role of antifungal and antiviral prophylaxis relative to oral mucositis, pain and xerostomia during head and neck RT.

Gamma knife output factor measurements using VIP polymer gel dosimetry.

PURPOSE Water equivalent polymer gel dosimeters and magnetic resonance imaging were employed to measure the output factors of the two smallest treatment fields available in a Gamma Knife model C radiosurgery unit, those formed employing the 4 and 8 mm final collimator helmets. METHODS Three samples of the VIP normoxic gel formulation were prepared and irradiated so that a single shot of the field whose output factor is to be measured and a single shot of the reference 18 mm field were delivered in each one. Emphasis is given to the development and benchmarking of a refined data processing methodology of reduced uncertainty that fully exploits the 3D dose distributions registered in the dosimeters. RESULTS Polymer gel results for the output factor of the 8 mm collimator helmet are found to be in close agreement with the corresponding value recommended by the vendor (0.955 +/- 0.007 versus 0.956, respectively). For the 4 mm collimator helmet, however, polymer gel results suggest an output factor 3% lower than the value recommended by the vendor (0.841 +/- 0.009 versus 0.870, respectively). CONCLUSIONS A comparison with corresponding measurements published in the literature indicates that output factor results of this work are in agreement with those obtained using dosimetric systems which, besides fine spatial resolution and lack of angular and dose rate dependence of the dosimeters response, share with polymer gels the favorable characteristic of minimal radiation field perturbation.

On the dosimetric accuracy of a Sievert integration model in the proximity of 192Ir HDR sources

PURPOSE To investigate the efficacy of a Sievert integration model in dosimetry close to 192Ir high-dose-rate brachytherapy sources and validate its accuracy and potential to resolve dosimetric differences between these sources in the cm and mm distance ranges relevant to interstitial and intravascular brachytherapy applications, respectively. METHODS AND MATERIALS The dosimetric quantities of the generalized Task Group 43 formalism, as well as dose rate profiles in polar and Cartesian coordinates, are calculated, and results are compared to corresponding Monte Carlo data in the literature. RESULTS Sievert calculations were found in excellent agreement with corresponding Monte Carlo published results. Dose rate polar angle profiles in the cm distance range depended significantly on corresponding anisotropy function data, whereas in the mm distance range, dose rate polar angle profiles are governed by the corresponding geometry function profiles, because anisotropy proved insignificant. Radial dose functions of the sources were found comparable. A simple equation for the calculation of the dose rate constant of the sources within clinically acceptable accuracy is provided. CONCLUSIONS The particular Sievert model proved capable of resolving dosimetric differences of the sources and provides results within clinical accuracy. Therefore, it constitutes a useful tool for dosimetry in clinical practice and especially in intravascular applications, where there is currently a lack of available dosimetric data.

Gamma Knife relative dosimetry using VIP polymer gel and EBT radiochromic films

The VIP polymer gel–MRI method and EBT Gafchromic films were employed to obtain relative dosimetry results for the Gamma Knife (GK) radiation fields of 4 mm and 18 mm nominal diameter. Results are compared to the corresponding calculations of GammaPlan Treatment Planning System (TPS) in the form of 1D profiles and 2D distributions. Measured and planned relative dosimetry datasets are found in close agreement within experimental uncertainties. A corresponding agreement is shown for Dose Volume Histogram (DVH) results that are available only through the application of the polymer gel method.

Oral Mucositis, Pain and Xerostomia in Patients with Head and Neck Cancer who Received Chemoradiotherapy with or without Cetuximab

Goal of work: To compare the severity of oral mucositis, pain and xerostomia in head and neck cancer patients, who received radiotherapy with cisplatin and cetuximab to that of patients who received radiotherapy with cisplatin alone. Patients: Forty-nine head and neck cancer patients entered the study. Twenty-five patients (Group A) received radiotherapy and cisplatin. Twenty-four patients (Group B) received radiotherapy, cisplatin, and cetuximab. Methods: Oral mucositis was recorded weekly, according to EORTC/RTOG criteria. Pain and xerostomia were assessed using a 10cm visual analogue scale. Antifungal and antiviral treatment and prophylaxis were administered during RT to both groups. Results: During chemoradiotherapy, severe mucositis, pain and xerostomia were observed in 60%, 64% and 52% respectively in Group A, while the same symptoms were observed in 79%, 58% and 29% respectively in Group B. The differences between the two groups were not statistically significant. At the end of chemoradiotherapy, severe mucositis, pain and xerostomia were recorded in 24%, 32% and 32% in Group A and 37%, 21% and 17% respectively in Group B. The differences between the two groups were, again, statistically not significant. Neither significant differences were found between the two groups with respect to the use of antifungal and antiviral treatment, radiotherapy interruptions and weight loss. In both groups, oral mucositis, pain and xerostomia were significantly reduced at the end of radiotherapy as compared to those during RT, following the anti-infectious treatment and prophylaxis. Conclusion: Cetuximab, added to cisplatin/radiotherapy, did not increase the severity of oral mucositis, pain and xerostomia, in head and neck cancer patients, with limitations of the study design and its limited number of patients.

Quality assurance of Siemen's virtual wedgeTMby using film dosimetry

A film dosi netry method is proposed for measuring the non-uniform dose distribution generated by Virtual Wedges of a 6 MV Siemens Pr mus accelerator. This method was chosen due to the dose integration capabilities and the improved spatial resolution that films offer, giving the opportunity of measuring dose distribution in a single beam irradiation. Dose profiles were obtained and analyzed using a 16-bit Vidar film scanner and OmniPro-Accept software. Results were compared with corresponding ones measured with an array ionization chamber for both virtual and conventional wedges. A good agreement was found between the two methods for all the examined wedge angles. This study shows that film, dosimetry can be incorporated in a monthly quality asseurance program for virtual wedges in order to reduce the required effort.