Iranian Journal of Medical Physics
Volume:20 Issue: 1, Jan-Feb 2023

We present a comprehensive evaluation of three different dosimeters in 6 MV flattening filter-free beam (FFF) under charged particle dis-equilibrium conditions.
Diamond detector, Gafchromic film, and Un-shielded diode detector were used in this study. The total scatters factor of Jaw-shaped fields was measured starting from (10x10 cm2) down to (0.5x0.5 cm2) using True Beam Linear Accelerator (Varian) and solid water phantom. 
The diamond detector presented more accurate results at an ultra-small field size (0.5x0.5 cm2) with a 14.1% deviation of the diode results. On the other hand, all the measurements ranged within 5% for large field sizes “i.e. Larger than 4.0x4.0 cm2”. The relative output factor (ROF) was introduced as a total scatter factor measured by a given dosimeter (x) to total scatter factor measured by diamond detector , the relative output factor values were 0.859 and 0.104 for both Diode/Diamond  and Film/Diamond , combinations, respectively.
We found that the diamond detector is the most appropriate detector for the small field dosimetry with high accuracy.

Myocardial perfusion imaging (MPI) is a valuable diagnostic tool for the diagnosis of coronary artery disease (CAD) and is susceptible to a variety of artifacts, which degrade image quality and decrease diagnostic accuracy. Pitfalls and Artifacts in nuclear medicine imaging are not rare and could be classified into issues related to patients, equipment, and technologist. One of these artifacts is unstable PMT gain, which is rare and related to equipment. It is crucial for nuclear physicians to be aware of potential artifacts and their potential effect on image quality. This knowledge helps them to prevent or correct these artifacts if possible and if not, consider the potential effect of these artifacts on image pattern and quality. Some of these artifacts are preventable by routine quality control procedures, but some other artifacts may occur regarding quality control procedures. Three different female subjects 55, 57, and 61 years old with a history of atypical chest pain were referred to our department for myocardial perfusion imaging. MPI was performed according to standard protocols and stress, and rest phases were done. These three cases had different patterns of perfusion abnormalities due to interruption of count detection for a few seconds in some frames during acquisition that was due to voltage drop that leads to unstable PM tube gain. Systematic errors due to voltage drops are not common, and they are not routinely sort of suspicion to artifactual perfusion abnormalities but they may cause misinterpretation of reports of MPI, and we should be aware of them.

This study aims to use the Intensity Modulated Radiation Therapy (IMRT) technique for prostate cancer patients to evaluate the effectiveness of four different commercial Treatment Planning Systems (TPS): (Eclipse, Monaco, Ray plan, and Prowess). In terms of Conformality Index, Homogeneity Index, the dose distributions, the mean dose, the maximum dose, number of segments in each plan for each TPS, Monitor Units per fraction for each treatment plan for each TPS, coverage of the PTVs, and avoidance of Organs At Risk (OARs) for Simultaneous Integrated Boost (SIB) for cancer prostate treatment plans.
CT images and volumes structure of 10 patients were used to make IMRT plans. The target volume’s structure was contoured according to RTOG 0534 protocol. Fixed beam geometry and clinical goals were set for all individual patient plans. The results were analyzed in terms of dosimetric parameters, the number of segments, and monitor units per segment.
All TPSs achieve similar coverage, and dose distributions to the PTVs. For PTV60 Eclipse achieved the lowest coverage relative to other planning and the nearest mean dose to prescription dose and significant difference relative to other planning. For PTV 44: the Ray plan achieved the best coverage with a significant difference relative to other systems, but Eclipse achieved the nearest mean dose to the prescribed dose with a significant difference relative to the ray plan. Prowess achieved the lowest MU/fraction with a significant difference relative to Monaco the highest in Mus and the lowest possible number of segments.
The four planning systems achieve close dose distributions and confirmation numbers but there is a significant difference in total segments per fraction and total monitor units per fraction which affect the long life of the machine and the session treatment time.

Radiosurgery is a well-established available technique for treating many diseases and indications. Planning quality assessment is a crucial step in the procedure itself and outcome probabilities; either control or complication probability. Several physical indices and methodology have been developed to describe any plan. Accordingly, plan quality and outcome could be compared with other plans. In current study, the aim was to compare two plans with different isodose line using radiobiological model, tumor control probability (TCP), normal tissue complication probability (NTCP) and plan’s physical indices.    The cross-sectional study included 20 patients (5 male and 15 female) with median age of 44 years (21-66) and presented with radiologically diagnosed meningioma. Two radiosurgical forward plans were applied with same marginal dose of 12Gy at two different isodose lines of 50% and 75% isodose alternatively using Leksell Gamma Plan of single session GKS. Dose-Volume Histogram (DVH) was imported to MATLAB to compute TCP, NTCP values at 5 years for each plan, and physical indices such as coverage, selectivity, conformity, heterogeneity, and gradient indices. Median target irradiated volume was 7.5 cm3 (0.588 -23.72). TCP was significantly higher in the plan using 50% isodose line for the marginal dose than that using 75% isodose line (95.05%, 49.44%, p<0.05, Independent Samples t-Test). Brainstem and optic apparatus NTCPs were very low 0.01% (0-0.045%) in the former plan and zero in the later one (p =0.001, Mann-Whitney test). Radiobiological models and physical indices could be used for the optimum plan selection of GKS

Due to the limited target volume and irregular body surface, irradiating the chest wall (CW) and lymphatic nodes is more challenging. IMRT and VMAT (volumetric modulated arc therapy) are two treatment delivery techniques that help to improve dose coverage and homogeneity while reducing irradiation to the heart and ipsilateral (I/L) lung. The use of a hybrid treatment planning approach for the ca-breast will impact the treatment plan. The hybrid planning system must be reviewed and compared to alternative treatment options for ca-breast cancer.
For 10 patients undergoing left-sided breast chest wall irradiation, the 3 distinct planning techniques (FiF [Field-in-field], IMRT, and Hybrid IMRT) were evaluated. A prescription dose of 40 Gy in 15 fractions was used for the planned target volume (PTV). To compare plans, dose-volume histograms (DVHs) were assessed for PTV and organs at risk.
D95% of PTV was 37.10 ± 0.48 Gy in FiF, but considerably raised to 39.32 ± 0.34 Gy and 38.39 ± 0.29 Gy in IMRT (p=0.01) and Hybrid IMRT (p=0.01).When compared to IMRT (0.981 ± 0.014) and Hybrid IMRT (0.970 ± 0.013) FiF plans have the lowest CI value of 0.931 ± 0.026. IMRT plans (0.087 ± 0.021) were found to be more homogeneous than other 2 planning techniques (0.111 ± 0.013 [FiF, p=0.016], 0.107 ± 0.021[hybrid IMRT, p=0.056]).
Hybrid IMRT treatment plans for the ca-breast are recommended because they provide superior and similar PTV dose coverage and OAR sparing compared to FiF and IMRT plans. Hybrid IMRT plans feature lower MU and BOT, as well as a smaller low dose volume in comparison to IMRT.

In this study, we aimed to identify the benefits in image contrast enhancement of Folic acid-Cysteamine conjugated gold nanoparticles (FA-Cys-AuNPs) by comparing Contrast to Noise ratio (CNR) of gold nanoparticles (AuNPs) to iodinated compound CT images. The CNR was assessed in different tube voltages, concentrations, and incubation times in nasopharyngeal KB cancer cells.
FA-Cys-AuNPs and Omnipaque suspension were scanned at different concentration ranges (500-2000 µg/ml) and energy ranges (80- 140 kVp) with CT imaging modality. FA-Cys-AuNPs and AuNPs were incubated in nasopharyngeal cancer cells at different incubation times (6, 12, and 24 h) and concentration ranges (200-500 µM). Finally, the contrast enhancement was assessed using CNR value at different tube voltages.
Results showed that the formed FA-Cys-AuNPs with an Au core size of 15 nm in all concentrations and tube potentials from 80 to 140 kVp display greater CNR than Omnipaque. The CNR value was increased by increasing concentration and energy. At 140 kVp and 2000 µg/ml, the CNR value of FA-Cys-AuNPs was 2.25 times greater than Omnipaque. At 140 kVp, 500 µM and 24 h incubation, the CNR values of targeted cells were approximately 1.5 times higher than non-targeted cells. At 140 kVp, and 500 µM, the CNR value of targeted cells with 24 h incubation time was 2.66 times greater than the targeted cells incubated with 6 h.
These findings suggested that the designed FA-Cys-AuNPs could be a good candidate contrast agent for molecular CT imaging.

Angiography is an X-ray-based technique for the diagnosis of disorders of the arteries, veins, and heart chambers. X-ray is a potential factor for the modulation of immune responses, including cytokines, the key molecules that participate in cardiovascular disease pathogenesis. Due to the potential roles of interleukin-6 (IL-6) and transforming growth factor-beta (TGF-β) in cardiovascular disease, this study was designed to evaluate the IL-6 and TGF-β serum levels before and after angiography in atherosclerosis suspected patients.
In this experimental study, the IL-6 and TGF-β serum levels were explored, using the enzyme linked immunosorbent assay (ELISA) technique, in the healthy controls as well as three groups, including atherosclerosis suspected patients without, obstruction of 1 and more than 1 vessel. The IL-6 and TGF-β serum levels also were evaluated before angiography and 3 hours after angiography in the last three groups. SPSS software was used for data analysis.
The results showed that TGF-β serum levels were significantly higher in the controls in comparison of other groups (p> 0.001). Angiography and smoking increased TGF-β (p= 0.027) and IL-6 (p= 0.035) serum levels, respectively, in atherosclerotic patients with obstruction of 1 vessel. Age had a positive, moderate correlation with IL-6 in the non-atherosclerotic patients (rs: 0.479, p= 0.039).
Down-regulation of TGF-β may be associated with induction of inflammation in the patients. Angiography, via up-regulation of TGF-β, may reduce inflammation in the patients and smoking may increase the progression of atherosclerosis in atherosclerotic patients. Age may increase the risk of cardiovascular diseases via up-regulation of IL-6.

The study focused on the assessment of quality control tests in X-ray units from the Southern regions of Tanzania to yield the data required to create and implement quality control policies and strategies. Quality control tests were conducted on twenty-six diagnostic X-ray units in private and government hospitals in southern regions of Tanzania during 2020 – 2021. The tests focused on the reproducibility of accelerating tube potential, time reproducibility, the accuracy of accelerating tube potential, half-value layer, beam alignment, and collimation. The statistical analyses were done by using the Microsoft Excel spreadsheet of 2013. The results were compared with the tolerance limits.  Of all X-ray units evaluated, 92.31% had kVp accuracy within the tolerance limit of 5% and 92% of the X-ray units had acceptable HVL values ≥ 2.3 mm Al at 80 kVp. Moreover, results have shown that 86.96% and 82.61% of X-ray units had acceptable beam collimation (≤ ±2 cm) and beam alignment (≤3% of the X-ray source and X-ray table), respectively. Comprehensive regulatory inspections and equipment maintenance plans in the Southern zone is significantly required due to the high patient workload which attributes frequent breakdown of X-ray units. Moreover, radiographers need to be trained on how to minimize and detect beam misalignment and collimation failure since the most unacceptable results were observed from these tests.