Nuclear Medicine & Radiation Therapy

The present study is undertaken to know the radiation dose-response of chromosomes in the non-target cells, viz. peripheral blood lymphocytes of cancer patients in a context of partial body irradiation. The genotoxic effect of γ- radiation was studied in Head and Neck Squamous Cell Carcinoma (HNSCC) patients exposed to various cumulative doses of 60Co gamma rays during radiotherapy (RT). These patients (P1 to P10) were irradiated for a period of six weeks with a daily fraction of 2 Gy, consecutively for 5 days in every week. The clastogenic effects of radiation in these patients were analysed on every weekend employing chromosomal aberration (CA) assay. Radiosensitivity of these patients were analysed by employing linear regression analysis of the CAs induced by irradiation. Genetic damage observed in all patients on a weekly basis were recorded and analysed at the individual level in comparison with their own pre-therapy baseline data, employing student’s t-test. Dicentrics, centric rings and chromatid breaks were observed as the major kinds of CAs. The total CAs observed were analyzed using two way ANOVA, showed significant (P<0.001) intra and inter-individual variations of the genotoxic effects. Further, a dose dependent increase of cytogenetic damage was observed in the non-target cells viz. lymphocytes. Further, cytogenetic studies in peripheral lymphocytes following gamma radiotherapy of tumors may help to understand the optimum/precise dose of radiation to be employed for RT, may also be useful to predict dosimetry and the possible secondary tumors in irradiated HNSCC patients.

Purpose: To evaluate baseline PET/CT SUVmax value and Neutrophil/lymphocyte ratio (NLR), as prognostic indicators of progression free survival (PFS) and overall survival (OS) in surgically treated oligmetastatic breast cancer (OMBC) patients.

Materials and Methods: The pretreatment 18FDG-PET-CT SUVmax and NLR in surgically treated OMBC patients were compared with clinicopathological parameters. The prognostic value of pretreatment SUVmax and NLR for PFS and OS were assessed using Log rank and Cox regression.

Results: Overall, 87 OMBC were included, mastectomy and axillary clearance was performed in 72 patients (83%) who responded to preoperative systemic. The receiver operator curve (ROC) demonstrated that SUVmax of 4.4 and 6.5 to be the cut off value for predicting PFS in patients with oligometastasis to bones and visceral organs respectively. Additionally, baseline NLR cut off value of 2.7 predicted PFS in all studied patients. In surgically treated 46 OMBC patients (64%) to bones SUVmax of >4.4 had a significantly shorter OS [Hazard ratio (HR 2.9)] <4.4 (P<0.01), whereas patients with SUVmax of ≤4.4 had significantly longer PFS compared with those with SUVmax >4.4 (P=0.02). Similarly, 26 OMBC patients (36%) to visceral organs with SUVmax ≤6.5 had significant improvement in OS compared to those with SUVmax >6.5 (HR 2.3)]. Moreover, patients with NLR ≥2.7 showed significantly lower PFS (HR, 2., P<0.001) and overall survival rate (HR,1.9, P=0.02) than patients with NLR<2.7. Cox regression multivariate for OS revealed that higher baseline SUV max and NLR along with visceral metastasis were independently correlated with poor prognosis, with HR 3.04, 8.83 and 9.21 respectively. Conclusion: The pretreatment PET-CT SUVmax and NLR showed

Accurate dose rate estimates is important for radiation protection specialists conducting risk assessments and performing dose reconstruction in cases of accidental exposures.

Objectives: The objectives of this work was to experimentally evaluate the bladder voiding factor effect on the dose rate measured from patients undergoing PET/CT imaging studies using 18F-FDG by directly measuring the dose rate immediately before and after voiding, and compare the results with the current scientific literature.

Results: The bladder voiding effect had a dose rate reduction factor of about 12% between dose rates measured before and after voiding. This measured reduction factor agreed with the 15% reported by the AAPM Task Group 108. We have also measured dose rates at one meter from 50 patients and found an average dose rate per unit activity of 93.7 μSv/hr/GBq. Our dose rate results were in excellent agreement with the results of current published data (92 μSv/hr/GBq, AAPM Task Group 108).

Conclusions: The presented data can be applied in radiation protection optimization procedures, especially for the protection of the care givers from patients undergoing 18F-FDG PET/CT imaging when they are considered as external radiation source or hazard to others. The provided information will benefit medical physicist working in nuclear medicine and radiation safety policy makers.

The radioiodine therapy is considered an almost definitive and successful hyperthyroidism treatment, alternative to surgery. Unlike a standardized activity approach is still adopted, a customized dosimetric study offers the significant advantage to take into account the individual variabilities in the structures to be treated. In the present work, some of the current issues relating to customized radioiodine treatment are discussed. The experience acquired during several years of customized hyperthyroidism radioiodine treatments performed at the S. Anna Hospital in Como (Italy) is presented, together with the main results of an extensive follow up analysis.

Background: The purpose of this study was to compare the dose distributions and treatment delivery efficiency of volumetric modulated arc therapy (VMAT) with flattening filter free (FFF) beams (FFF-VMAT) against VMAT with flattening filter (FF) beams (FF-VMAT) and Helical TomoTherapy (HT) for head and neck cancer.

Methods: Ten patients with nasopharyngeal and oropharyngeal cancer were chosen for this planning comparison study. Three treatment plans (dual arc FFF-VMAT, dual arc FF-VMAT, and HT) were created for each patient. The three prescription dose levels of the planning target volumes were 69.96, 60, and 54 Gy in 33 fractions, using the simultaneous integrated boost technique. Comparisons of the plan quality were performed by analyzing the homogeneity, conformity, dose to the organs at risk (OARs), the number of monitor units (MUs), and beam-on time (BOT) necessary for delivering the plans.

Results: The target coverage and sparing of the OARs for FFF-VMAT were almost equivalent to those for FFVMAT and HT. Compared to FF-VMAT, FFF-VMAT and HT significantly increased the number of MUs. The BOTs were the same for FFF-VMAT and FF-VMAT but significantly increased for HT.

Conclusion: We here present the first report of FFF-VMAT achieving a comparable plan quality with less delivery time to that of FF-VMAT and HT in head and neck cancer. FFF-VMAT is a highly efficient and feasible option for the treatment of head and neck cancer in clinical practice.

A 54-year-old male was taken to a hospital after experiencing persistent back pain for a month. A spinal column MRI showed a mass in T5-T8 fanterior edge. After four months follow-up, another MRI revealed the mass had grown up to the site of T3-T9. An 18F-FDG PET/CT imaging was underwent and the imaging showed three tumors mass which all had a high uptake of 18F-FDG locating in thorax, abdomen and pelvis, respectively. The thoracoscopic biopsy histological revealed the mass was mesenchymal tumor and immunohistochemistry showed positive for CD34 and CD39, that all proved the mass is solitary fibrous tumor.

68Ga-DOTA-TATE PET/CT is widely used in functional imaging of neuroendocrine tumors (NETs) and is superior to conventional somatostatin receptor scintigraphy (SRS), which is recommended for low grade NETs according to NANETS/ENETS guidelines. On the contrary 18F-FDG PET is suggested in patients with high grade NETs or when SRS is negative. However, tumor heterogeneity is a common finding along with NETs and causes differential expression of somatostatin receptor (sstr) and various FDG metabolisms. Here, we present a case where tumor heterogeneity is revealed with combined use of 18F-FDG PET/CT and 68Ga-DOTA-TATE PET/CT in the same patient and how does it influence clinical decision-making Conclusion: We here present the first report of FFF-VMAT achieving a comparable plan quality with less delivery time to that of FF-VMAT and HT in head and neck cancer. FFF-VMAT is a highly efficient and feasible option for the treatment of head and neck cancer in clinical practice.

Sacrococcygeal teratoma (SCT) is a neoplasm that arises in the sacrococcygeal region and is derived from multiple primitive germ layers. It is the most common congenital neonatal tumor but rarely seen in adults. The standard care for sacrococcygeal teratomas is complete surgical resection of the tumor. The presence of malignant transformation is associated with a less favorable outcome.

The aim of this study is to assess and evaluate the significant of performing patient's specification quality assurance (QA) for patients diagnosed with squamous cell carcinoma of the tongue (SCC) whom treated with intensity modulated radiation therapy (IMRT). The study was done in twelve pre- treatment's plans that been prepared for patients. All the ten selected plans are going to be treated with split-field (SF) technique for intensity modulated radiation therapy (IMRT) planning using 10 MV beams and a prescribed dose between 66Gy and 74 Gy. For quality assurance protocol we are using the two-dimensional ionization-chamber array. The study showed that an agreement between the measured dose and the pre-planned dose using TPS. All the plans passed >95% Gamma with the pixels within 5% distance to agreement 5 mm for IMRT patient-specific quality assurance (QA). It concludes that intensity modulated radiation therapy (IMRT) has the ability to deliver a highly conformal dose distribution to the planning target volume while sparing the organs at risk. However, the result showed a very good agreement between measurements dose and calculations dose which lead and proved that the planning using IMRT treatment are accurately done.