Iranian Journal of Medical Physics
Volume:20 Issue: 3, May-Jun 2023

The aim of this study was to select parameters from a combined analysis of breast compression, breast morphometry and volumetric breast density, telling about the overall quality of breast positioning, and to apply these investigations on a Moroccan population at the start of new breast cancer screening activities. The study found that compression force in mammography varies greatly and has no specific limit. The researchers attempted to find correlations between compression force and mammographic factors to establish a range of values for standardized compression in mammography. The study was carried out in a university hospital, a candidate screening center, provided with new technology equipment, qualified staff and doctors of different specialties. Image acquisition was procured on a FFDM Siemens Inspiration system for 250 patients in diagnostic mammography and all patients’ information was collected. The data about dose, the compression force and the thickness of the compressed breast were obtained directly from the DICOM header information, applying Volpara Density software. The results show a correlation between compression force and breast density. The volume of breast tissue compared to the total volume of the breast (VBD) decreased with increasing compressed breast thickness (CBT) and age. The mean VBD was 9.3% ± 6%, the compression force was 71±15 N and the CBT was 53±11 mm. The global analysis and comparison of mammographic parameters showed good similarity between Moroccan and the previous studies population. The mammographic techniques can therefore be used to Moroccan screening programs.

Radiation dose monitoring is an important objective of radiation safety and quality assurance program. The purpose of this study was to develop an automated approach for monitoring and estimating patient radiation doses from Computed Tomography (CT) examinations, Automated software, based on MATrix LABoratory (MATLAB) environment, was introduced for extracting and analyzing  patient dose identifiers from Digital Imaging and Communications in Medicine (DICOM) CT image files. In addition, an estimation of effective dose and statistical studies were implemented. A random sample of 1466 patients’ CT DICOM image files were collected from a 64-slice Siemens’ Somatom Perspective CT scanner. The proposed Graphical User Interface (GUI) extracts the volumetric CT dose index (CTDIvol), the dose length product (DLP) for each phase of scan session in order to calculate the patient radiation effective dose (E). A graphical layout presenting statistical values was were also produced, e according to study date, patient sex, and CT protocol type. The GUI performance was verified according to the manually proceeded results. The extraction speed and accuracy of the radiation dose values were satisfactory, as compared to the approaches presented in literatures such as optical character recognition (OCR) technology, and the direct extraction from the metadata of CT image files. The proposed GUI performs the extraction of CT patient dose metrics CTDIvol, DLP with a satisfactory speed and accuracy. The obtained results could be shown in numerical and graphical formats, and it could be used for radiation dose monitoring and Diagnostic Reference Levels (DRLs) establishing purposes with multiple filtering capacities.

Due to the high radiation dose used in radiotherapy, the human tissue is usually replaced with tissue substitutes in order to develop new treatment techniques. Tissue substitutes have not been reported for colorectal cancer tissue (CRC). This study aims at developing tissue substitutes for the CRC tissue with respect to the mass attenuation (µm) and mass energy absorption coefficients (µen/ρ) within the energy range of 6 – 15MV.
Colorectal cancer tissue and four locally sourced materials namely beeswax, gelatine, rice powder, clay, and their mixtures – Clarice, gelarice, gelaclay, and bewaclay were subjected to Rutherford Backscattering Spectrometry (RBS) to determine their elemental composition. Results from the RBS were used in XCOM, a web-based photon interaction software designed by the National Institute of Standards and Technology, USA to determine their theoretical µm and µen/ρ values. Again, these materials were exposed to a narrow beam of x-rays at energies of 6 and 15MV to obtain their experimental µm and µen/ρ values.
Revealed that the ratio of CRC tissue to the test materials ranged from 0.946 (beeswax) to 1.07 (clay) for both theoretical and experimental values with bewaclay having a ratio of 1.01 compared with 1.00 for CRC and a p = 0.541 and p = 0.663 with respect to µm and µen/ρ respectively.
Bewaclay with the closest match can be used as a tissue substitute for the CRC tissue between 6 – 9MV with respect to µm and µen/ρ as parameters for matching.

stereotactic body radiotherapy (SBRT) is the most proper treatment for multi lesions non-small cell lung cancer (NSCLC) for enhanced good coverage and minimizing dose to organs at risk (OARs). This study aims to compare single and dual isocenter SBRT plans and discuss which technique we can use in multi lesions NSCLC.
Ten patients with multi targets NSCLC underwent two different SBRT treatment planning techniques including single isocenter and dual isocenter. We quantitatively assessed plans qualities by dose-volume metrics. Conformity index (CI), Confirmation Number (CN), heterogeneity index (HI), gradient distance (GD), Gradient index (GI), and maximum percentage dose at 2cm all around PTV ( ) were gathered, tallied, and statistically examined. OARs were evaluated and the dose to the normal lung was evaluated using V5, V10, V20, and mean lung dose (MLD).
There is an insignificant difference between single and dual isocenter plans in CI, CN, HI, GD, GI, and dose spillage where the mean distance between two lesions was 5.50 ± 1.50 cm, and the mean total volume of the planning target volume (PTV) was 42.60±21.33cc. For single and dual isocenter plans, the median MLD was 4.5(2-16)Gy and 4 (2-16)Gy respectively (p=0.25).
Plan quality of single isocenter was equal to dual isocenter for SBRT treatment of multi lung lesions with maximum distances between them was 10 cm.  Dual isocenter took time during setup and matching for cone beam computed tomography (CBCT).

While various algorithms are applied in acquiring diagnostic information during computed tomography, such algorithms may affect image quality. The present study aimed to investigate the changes in image quality according to the application of the metal reduction algorithm and monoenergetic image in standard imaging. Spectral computed tomography was used to acquire images with the application of standard, metal artifact reduction, monoenergetic, and monoenergetic+metal artifact reduction under the same conditions according to without or with of metal in ACR phantom. ImageJ program was used to measure the HU, noise, and SNR of polyethylene, bone, and acrylic located inside the ACR phantom using the same-sized ROIs. HU measurement results showed changes in all materials, except acrylic with metal artifacts in the images. Moreover, the results showed a decrease in HU in images with the application of monoenergetic. Noise measurement results also showed changes in all materials, except acrylic with metal artifacts in the images. Moreover, the results showed a decrease in noise in images with the application of monoenergetic. For SNR measured relative to standard images, the results showed degradation of image quality due to a decrease of 36.5–77.7% in SNR and an increase in error value in all materials except acrylic. Whereas, acrylic showed an increase of 3.2–4.1% and a decrease in error values, resulting in improved image quality. Therefore, it is believed that the accuracy of reading could be increased by considering the changes in image quality and characteristics when applying algorithms for acquiring clinical information from CT.

With the introduction of Intensity Modulated Radiotherapy (IMRT) approach, better dosimetry results and patient outcomes has been attained for various anatomical sites. In present study, a comparative dosimetric evaluation of Volumetric-Modulated Arc Therapy (VMAT) versus two techniques of IMRT i.e. Dynamic IMRT (d-IMRT) and step & shoot IMRT (ss-IMRT) was done for thoracic esophageal cancer. VMAT, ss-IMRT, and d-IMRT plans were generated on the Computed Tomography Simulator data sets of 13 Patients with thoracic esophageal carcinoma who had been treated earlier. The prescription dose for each patient was 50.4 Gy in 28 fractions. All the plans were optimized to achieve greater or equal to 95% of the prescribed dose to the Planning Target Volume (PTV). Dose to PTV and organ at risk (OAR) were compared with the help of Dose Volume Histogram (DVH). VMAT and d-IMRT plans were nearly equivalent for PTV coverage, homogeneity index (HI), and uniformity index (UI) (p> 0.05). However, VMAT and d-IMRT plans had superior PTV coverage, HI, and UI, (p < 0.01) than ss-IMRT. For PTV, the Dmean, D98, and D95 values in ss-IMRT were significantly less than VMAT and d-IMRT (p< 0.05). All three techniques are able to provide a homogeneous and conformal dose distribution. VMAT offers better homogeneous dose distribution and may be preferred for treating thoracic esophageal carcinoma. Thus, the multi-arc VMAT technique may be a better option with equivalent or superior dose distribution, uniformity, and homogeneity.

Due to the challenge of choosing the optimal treatment regimen as well as the accurate dose calculation algorithm (DCA), this study aimed to evaluate the DCAs to compare the conventional fractionation radiotherapy (CFRT) and hypofractionation radiotherapy (HFRT) of breast cancer (BC) in the prediction of cardio-pulmonary complications.
For 19 patients with left-sided BC, treatment regimens, CFRT (50Gy/25frs) vs. HFRT (42.5Gy/16frs), were simulated. Normal tissue complication probability (NTCP) and tumor control probability (TCP) values for each regimen using radiobiological models were calculated via Monte Carlo (MC) and Collapsed Cone Convolution (CCC) algorithms. For statistical comparison of the results obtained from the regimens and algorithms, the t-test and Wilcoxon test were used in SPSS Statistics. Statistical significance was defined as p<0.05.
The mean NTCP and TCP calculated in CFRT and HFRT were as follows: cardiac mortality (MC: CFRT=0.0374±0.0134 vs. HFRT=0.0173±0.0066; p<0.001) and (CCC: CFRT=0.0373±0.0134 vs. HFRT=0.0168±0.0064; p<0.001), pneumonitis (MC: CFRT=0.1201±0.0322 vs. HFRT=0.0756±0.0221; p<0.001) and (CCC: CFRT=0.1131±0.0310 vs. HFRT=0.0697±0.0120; p<0.010), and TCP (MC: CFRT=0.9979±0.0087 vs. HFRT=0.9997±0.0092; p=0.593) and (CCC: CFRT=0.9982±0.0029 vs. HFRT=0.9986±0.0016; p=0.821).
The comparison of CFRT and HFRT using MC and CCC algorithms showed that the risk of cardiac mortality and pneumonitis in CFRT was significantly higher than in HFRT, and TCP was not significantly different in the two regimens. Applications of MC-based DCAs along with suitable biological parameters can help physicists in the prediction of radiation-induced complications accurately and precisely.

Multifunctional of cancer-specific tumor biomarkers is a potent therapeutic approach to treat cancer diseases with high efficacy. Among these methods that can be mentioned are the composition and design of nanoparticles and photosensitizers (PS). The purpose of this study is to investigate the effect of gold nanoparticles (GNPs) coated thioglucose (Tio) combined with methylene blue photosensitizer to enhance the efficacy of hybrid therapy (photodynamic and radiation therapy). First, GNPs-Tio was synthesized. Next, the toxicity of GNPs-Tio, MB, and their combinations was determined on the MCF-7 cell line to achieve their optimal concentrations. In the next step, the efficacy of combination therapy was evaluated using hybrid therapy. For this purpose, an optical dose of 15.6 J/cm2 and 2 Gy for radiation therapy were delivered. Cell viability was evaluated using MTT and colony assays. According to the MTT assay, the combined photodynamic and radiation treatment of GNPs-Tio did not cause significant cell death. But this induced significant cell death by using GNPs-Tio + MB while the cell survival rate was almost zero. Combined therapy caused significant cell death in the presence of each of the pharmacological agents alone and their combination in colony assay. The difference in treatment results between the MTT and the colony assay can be due to the more accurate colony assay for cell death detection. Significant cell death was achieved in the combination of photodynamic and radiotherapy in the presence of MB and MB + GNP-Tio.

This study aims to address the radiation exposure incurred by lung scintigraphy in pregnant patients suspected of pulmonary embolism and to investigate the dose variations due to different body habitus of the fetus.
In this respect, seven computational models of pregnant women and fetus in three trimesters of pregnancy were used and Monte Carlo calculations were performed using Monte Carlo n-particle –extended (MCNPX) code version 2.6.0 to assess absorbed dose coefficients. Time-integrated activities for three radiopharmaceuticals considered in this study were also extracted from the available reference biokinetic data.
Fetal dose coefficients (mGy/MBq) for three radiopharmaceuticals labeled with 99mTc were estimated for reference pregnant phantoms at three trimesters of gestation and 10th, and 90th fetal growth percentiles were also considered during the last two trimesters. The results show that the fetal dose coefficients were 2.09 × 10-2, 5.71 × 10-3, and 4.44 × 10-3 mGy/MBq for 99mTc MAA, 8.31 × 10-4, 8.68 × 10-4, and 1.27 × 10-3 mGy/MBq for 99mTc Technegas, and 7.85 × 10-3, 2.42 × 10-3, and 2.66 × 10-3 mGy/MBq for 99mTc DTPA aerosol, respectively. According to the results the factor of fetal body habitus adds variation to the fetal dose within ±15%.
Considering one of the uncertainty components of fetal dose, that is the fetal body habitus, the dose variations were well below the safety threshold for the fetus (the threshold from ICRP Publication 84 for fetal cancer risk). Therefore, to check the safety of the diagnostic examination in terms of radiation dose to the fetus, it is sufficient to take into account the reference dose values in clinical practice.