Iranian Journal of Medical Physics
Volume:21 Issue: 1, Jan-Feb 2024

Breast cancer has been a leading malignancy in women across the globe. In breast conserving treatment, radiation therapy plays an important role. This is clinically approved that breast conserving surgery followed by adjuvant radiation therapy produces as the same survival rate as radical breast RT. The aim of this study was to find out suitable number of IMRT fields to treat left-sided breast cancer and analyze the effects of increasing the number of fields in IMRT plans.We selected 105 patients retrospectively for this study diagnosed with left-sided breast cancer of age ranging from 33 to 74 years.  There were 52 cases of chest wall (CW) irradiation including SCF, 20 cases of BCS and 33 cases were of CW including supra-clavicular fossa (SCF) and internal mammary lymph nodes (IMLN).Our main objective was to analyze dose-distribution of left lung. Monitor Units (MUs) were also recorded and found almost same in these three modalities ranging from 1200 to 2000. The mean value of V20Gy(cc) in 11-bIMRT technique was found less by 8-17cc as compared to 7-and 9-bIMRT technique. It was observed that 11-bIMRT technique yielded slightly better outcomes in terms of V20Gy(cc). The technique 7-bIMRT gives slightly better result in controlling low-dose volume of underlying lung and heart. As the number of IMRT beams increases, it translates into better outcomes in terms of reducing high-dose volume as well as mean-dose of left lung. So, it is prudent to use ‘N’ number of IMRT fields such as 7≤ N ≤11 in left breast RT.

Mammographic density is a significant risk factor for breast cancer. Classification of mammographic density based on Breast Imaging Reporting and Data System (BI-RADS) is usually used to describe breast density categories but the visual assessment can have some restrictions in a routine check in the screening mammography centers. The object of this study was to investigate the effectiveness of artificial neural networks in predicting breast density, based on the clinical patient dataset in a University hospital. In this study, mammographic breast density was assessed for 219 women who underwent digital mammography screening using Volpara software. A model based on the Multi-Layer Perceptron Neural Network was trained to predict patient density by identifying the (dense vs. non-dense) breast density categories. The predictive model applied to the classification was examined by the Receiver operating characteristic (ROC) curve. The results show that the model predicted the breast density of patients with a classification rate of 98.2%. In addition, the area under the curve (AUC) was 0.998, signifying a high level of classification accuracy. The use of artificial neural networks is useful for predicting patients breast density based on clinical mammograms.

This study aims to investigate the Normal Tissue Complication Probability (NTCP) and Tumor Control Probability (TCP) of cervical cancer from Niemierko radiobiological model and compared with Lyman-Kutcher-Butcher (LKB) model’s effective volume parameter in three different planning techniques such as 3-Dimensional Conformal Radiation Therapy (3D-CRT), Intensity Modulated Radiotherapy (IMRT) and Volumetric Arc Therapy (VMAT).Twenty patients were selected with Grade II and Grade III and the treatment plan was initially generated for 3D-CRT, IMRT and VMAT. The physical dose from each voxel in radiotherapy treatment planning was extracted through a dose volume histogram (DVH) text file from in-built software developed using python program.  Software was developed by freely available python integration with an integrated Oracle database to store the outcome results with user-friendly graphical user interface for editing the radiological parameter values and viewing the DVH graph. The dosimetricconformalities parameters such as homogeneity index (HI) and conformity index (CI) along with radiobiological parameters such as TCP, NTCP and effective volume (Veff) were compared with three different planning techniques.The IMRT and VMAT dose delivery techniques improve the efficiency of the treatment of cervical cancer with good coverage of target volume as well as low irradiation of Organ at Risk (OARs) compared with 3D-CRT. There is no significant difference in effective volume for IMRT and VMAT, which proportionally increases with the advanced planning techniques, causes insignificant complication probability to normal tissues. Other conformalities parameters were showing good agreement for all the three techniques.

Popularly, teletherapy (telecobalt/LA) equipment is based on a C-arm gantry system. Recently, a fast O-ring gantry system introduced a medical linear accelerator (LA) to smoothen the workflow of treatment of cancer patients because of the increasing trend of the number of cancer cases over the past few years. This study aimed to analyze the commissioning parameters and validation of the O-ring gantry-based LA for improved radiotherapy techniques.
Three-dimensional (3D) radiation field analyzer (RFA) used to commission HalcyonTM LA. It is used for measuring percent depth dose (PDD), profiles, and output factors.
TPS data was validated by comparing it with our measured data. Plans per the TG-119 protocol showed good agreement between treatment planning systems (TPS) calculated and measured doses. For patient-specific, QA plans showed good agreement with gamma evaluation criteria.
Commissioning and validation of O-ring gantry system HalcyonTM LA was performed successfully.

This research aims to find an alternative oral contrast agents that can be used in magnetic resonance imaging (MRI) of the gastrointestinal (GI) tract, this contrast agent must be with no or minimum side effects and gives a best imaging quality.
We have used manganese supplement (intake daily dose) after dissolving in different amounts of distilled water to obtain samples (the concentrations of the manganese solution) as oral contrast agents. The samples have been placed in tubes and imaged by MRI for finding the sample that has lowest concentration with best imaging sequences and contrast of the images. After that, this sample was tested by healthy volunteers. The subjects of the investigation were ten healthy volunteers who were scanned pre-contrast and post-contrast. The image result is measured by the signal value to calculate the SNR, contrast and then a different test is performed. There were significant variations in stomach SNR values between pre and post contrast (p-value ).
The results show that the manganese supplement gives a good imaging sequences and contrast of the images. The contrast of manganese solution is positive on T1-weighted and negative on T2-weighted.This manganese supplement behavior is similar to the complex chemical manganese compounds studied in other investigations.
The manganese supplement can be considered as a positive contrast agent on T1-weighted and negative contrast agent on T2-weighted.

Iron deposition is vital for damaging neurons and causing different cognitive disorders. Today, using the quantitative susceptibility mapping (QSM) technique, iron deposits in other brain areas can be assessed and measured. This study aimed to identify changes in iron deposition of 12 brain nuclei through different stages of dementia using the QSM technique to introduce biomarkers for the early detection of cognitive disorders.
The Alzheimer’s Disease Neuroimaging Initiative (ADNI) database was used to download data. A 3T MRI scanner scanned thirty-five participants with normal cognition and forty-six patients with cognitive disorders who were classified into four groups based on the severity of the condition. QSM processing determined twelve regions of interest (ROIs) by automatic nuclei segmentation and statistical analysis performed in these groups’ MRI images.
Based on previous findings, QSM values ​​increase proportionally to iron deposition.In this study, the increase in the QSM values ​​of different nuclei of the early mild cognitive impairment (EMCI) stage indicates iron deposition in these participants. In the EMCI group, The QSM value of the bilateral thalamus (P<0.05) and left amygdala (P=0.006) nuclei were higher than in the control group. Based on the results of the receiver operating characteristic curve (ROC) analysis, the left amygdala (P=0.005), left putamen (P=0.002), left thalamus (P=0.05), and right thalamus (P<0.05) have an appropriate sensitivity and specificity to identify the different stages of cognitive disorders.
The left amygdala and bilateral thalamic nuclei are the first areas exposed to iron deposition during cognitive impairment. Mentioned nuclei, especially the left amygdala, have high efficiency and sensitivity for the early detection of cognitive disorders.

Our goal is to design and construct a new anthropomorphic head phantom for assessment of image distortion in treatment planning systems.
In this study, CT scan images of heads were transferred to the Mimic software. Using this software, the skull texture was removed and a hollow layer was formed between the bone tissues, in which the bone tissue would be equivalent to the material. Then it was fabricated with a 3D printer using K2HPO4 (as bone). A new phantom containing 8,000 reference features (control points) with AutoCAD software designed, fabricated it with a 3D printer and filled it with gels that included nickel-doped agarose, urea, and sodium chloride (as soft tissue) and then placed this grid inside the head phantom. This phantom was tested on the Siemens 3 Tesla Prisma MRI model using a 64-channel head coil. In this regard, a three-dimensional reference model was used. Reproducibility on the phantom was investigated with three different imaging sessions per day for three different days.
T2 gel value, 84.804 ± 3ms was obtained for gel that simulates brain tissue. In addition, their corresponding T1 measurements were 1090.92 (ms), respectively. By Adding nickel to agarose gels, the amount of CT number in all energies of 80 to 130 kVp increased. Increasing the concentration of nickel in gels results in a decrease in CT number. The geometric distortion in the 3D results was found to be due to field non-uniformity and nonlinearity of the gradients and its reproducibility.
The results show that, the amount of distortion in the middle of the field was less than that of its sides. This phantom can be used to check image distortion in treatment planning systems.

The objective of this work is to design a new kind of AHFP phantom to determine if this phantom is a realistic representation of actual cervical cancer patients. This can serve as a stand-in for the dosimetry quality assurance of a real patient.
An anthropomorphic heterogeneous female pelvic phantom was designed which was made of paraffin wax, a female pelvic bone, water, gauze, polyvinyl chloride (PVC) and polymerized siloxanes. The AHFP phantom was scanned using a CT scanner (Toshiba Alexion 16 multi–Slice CT scanner) at 120kVp and 250mAs with a slice thickness of 2mm to assess how accurately the resulting phantom product simulates a real patient. The CT images were transferred to the Eclipse treatment planning system for dosimetry analysis.
The AHFP phantom's CT numbers and relative electron densities of the uterus, bladder, rectum, muscles, fat, bones, and cavities were found close to real patients. The mean percentage variations between planned and measured doses of all RapidArc QA plans were of 2.14 % and standard deviation of 0.543 (t=0.135, p= 0.447; p>0.05) for homogeneous phantom¸ and 7.57% & standard deviation 2.358 (t=4.674, p=0.00094; p< .05) for AHFP phantom.
It is concluded that the existing algorithms in TPS for dosimetry are working fine for homogeneous phantoms, but it does not work good for heterogeneous (AHFP) phantom. Therefore, patient-specific absolute dosimetry should be performed using a heterogeneous phantom that closely resembles the actual human body in terms of both density and design.