UV/Vis dose response of a reusable PMMA-NaCl polymer composite.

PURPOSE: Two-dimensional dosimeters are convenient tools for quickly checking the radiation profile in radiotherapy. The currently used solution is costly, especially in busy institutions with extensive quality control procedures. This study fabricates a reusable 2-mm-thick PMMA-NaCl polymer composite sheet and assesses its dosimetric properties. METHODS: The PMMA-NaCl composite sheets were prepared using hot melting procedures. For dosimetric evaluations, the samples were irradiated using 6 MV X-ray photons from a medical linac. The absorbed doses were measured as changes in the optical absorption spectrum using a UV-Vis spectrometer. RESULTS: The lowest dose detected by the samples was 5 Gy, with a linear dose response of at least 20 Gy. The repeatability of the measurements was good, with a standard deviation of 5.03%. The signal was bleachable by using a 100 W filament-type lamp for dosimetric reuse. CONCLUSION: The 2-mm-thick PMMA-NaCl polymer-composite sheet could measure absorbed radiation doses from 6 MV X-ray photons down to 5 Gy. Because the sample is reusable, it can be used in a cost-effective two-dimensional radiation dosimeter to ensure the quality of medical linacs.

Design of InnoPrimers-Duplex Real-Time PCR for Detection and Treatment Response Prediction of EBV-Associated Nasopharyngeal Carcinoma Circulating Genetic Biomarker.

Nasopharyngeal carcinoma (NPC) is an epithelial tumor with high prevalence in southern China and Southeast Asia. NPC is well associated with the Epstein-Barr virus (EBV) latent membrane protein 1 (LMP1) 30 bp deletion by having its vital role in increased tumorigenicity and decreased immune recognition of EBV-related tumors. This study developed an InnoPrimers-duplex qPCR for detection of NPC blood circulating LMP1 30 bp deletion genetic biomarker for early diagnosis and treatment response prediction of NPC patients. The analytical and diagnostic evaluation and treatment response prediction were conducted using NPC patients' whole blood (WB) and tissue samples and non-NPC cancer patients and healthy individuals' WB samples. The assay was able to detect as low as 20 ag DNA per reaction (equivalent to 173 copies) with high specificity against broad reference microorganisms and archive NPC biopsy tissue and FNA samples. The diagnostic sensitivity and specificity were 83.3% and 100%, respectively. The 30 bp deletion genetic biomarker was found to be a good prognostic biomarker associated with overall clinical outcome of NPC WHO type III patients. This sensitive and specific assay can help clinicians in early diagnosis and treatment response prediction of NPC patients, which will enhance treatment outcome and lead to better life-saving.

Maximum standardized uptake value from quantitative bone single-photon emission computed tomography/computed tomography in differentiating metastatic and degenerative joint disease of the spine in prostate cancer patients.

OBJECTIVE: Qualitative interpretation in bone scan is often complicated by the presence of degenerative joint disease (DJD), especially in the elderly patient. The aim of this study is to compare objectively 99mTc-MDP tracer uptake between DJD and osseous metastases of the spine using semi-quantitative assessment with SPECT SUV. METHODS: Bone scan with SPECT/CT using 99mTc-MDP was performed in 34 patients diagnosed with prostate carcinoma. SPECT/CT was performed based on our institutional standard guidelines. SUVmax based on body weight in 238 normal vertebrae visualized on SPECT/CT was quantified as baseline. A total of 211 lesions in the spine were identified on bone scan. Lesions were characterized into DJD or bone metastases based on its morphology on low-dose CT. Semi-quantitative evaluation using SUVmax was then performed on 89 DJD and 122 metastatic bone lesions. As most of the bone lesions were small in volume, the effect of partial volume effect (PVE) on SUVmax was also assessed. The corrected SUVmax values were obtained based on the recovery coefficient (RC) method. RESULTS: The mean SUVmax for normal vertebrae was 7.08 ± 1.97, 12.59 ± 9.01 for DJD and 36.64 ± 24.84 for bone metastases. The SUVmax of bone metastases was significantly greater than DJD (p value < 0.05). To assess for diagnostic accuracy, receiver operating characteristic (ROC) curve was performed. The area under the curve (AUC) was found to be fairly high at 0.874 (95% CI 0.826-0.921). The cutoff SUVmax value ≥ 20 gave a sensitivity of 73.8% and specificity of 85.4% in differentiating bone metastases from DJD. The corrected SUVmax for both DJD and bone metastases was smaller with a mean of 6.82 ± 6.02 and 24.77 ± 20.61, respectively. The cutoff SUVmax value was also lower with a value of 10, which gave a sensitivity of 73.8% and specificity of 86.5%. CONCLUSION: SPECT SUVmax was significantly higher in bone metastases than DJD. Semi-quantitative assessment with SUVmax can complement qualitative analysis. A cutoff SUVmax of ≥ 20 can be used to differentiate bone metastases from DJD. Partial volume effect should be taken into consideration in the quantification of small lesion size.

A Case Rarity: Papillary Thyroid Carcinoma with Squamous Metaplasia Complicated with Chronic Discharging Ulcers.

We report a unique case of differentiated thyroid carcinoma (DTC) with squamous metaplasia complicated with chronic discharging ulcer. A 76-year-old gentleman was referred to us after defaulted treatment 1 year post-total thyroidectomy. He presented to us with long-standing chronic, non-healing, ulcerative and discharging wound at the anterior neck at previous total thyroidectomy scar. The primary tumour was histologically diagnosed as papillary malignant cells with extensive squamous metaplasia. Squamous metaplasia is a rare finding in thyroid carcinoma that carried a poorer prognostic factor.