Medicina nuclear y radioterapia

Diffuse large B-cell lymphoma (DLBCL) is a type of cancer that originates from the B-lymphocytes, which are a type of white blood cells responsible for producing antibodies that fight infections in the body. DLBCL is the most common type of non-Hodgkin's lymphoma, accounting for approximately 30% of all cases. It is an aggressive cancer that can develop anywhere in the body, including lymph nodes, bone marrow and other organs. Symptoms of DLBCL can vary depending on the location and extent of the cancer. Common symptoms include enlarged lymph nodes, fever, night sweats, weight loss, fatigue and unexplained pain or swelling. These symptoms are often non-specific and can be caused by other conditions, making it important to consult a healthcare provider if they persist.

Polymer gel dosimetry is a technique that is used to measure the radiation dose in three-dimensional space. This technique uses a gel that is sensitive to radiation and can be used to create a detailed map of the dose distribution within a volume of tissue. The gel used in polymer gel dosimetry is typically made up of a water-based solution containing a radiation-sensitive polymer.

Palliative radiation therapy is a type of radiation therapy that is aimed at relieving symptoms rather than treating cancer itself. This treatment is commonly used in patients with bone metastasis, which occurs when cancer cells spread from their original site to the bones. Bone metastasis can cause significant pain and discomfort for patients, and palliative radiation therapy can help alleviate these symptoms and improve their quality of life. Palliative radiation therapy is used to treat the specific area of bone affected by metastasis. The radiation is delivered in small, daily doses over the course of several weeks.

Computed tomography (CT) scan is a diagnostic imaging test that uses X-rays and computer technology to produce detailed images of various body parts. It is a commonly used medical tool that helps physicians diagnose and treat a wide range of conditions. During a CT scan, a patient lies on a table that slides into a large, doughnut-shaped machine. The machine takes multiple X-ray images from different angles around the body, which are then processed by a computer to create cross-sectional images, or slices, of the body part being examined.

Polymer gel dosimetry is a promising technique in radiation therapy to measure and verify the delivered radiation dose. It is a three-dimensional dosimetry method that uses a polymer gel as a dosimeter. This gel is made up of a mixture of monomers, initiators and other chemicals that polymerize when exposed to radiation. The polymerization process changes the optical density of the gel, allowing the dose distribution to be visualized using magnetic resonance imaging (MRI).

Combined supine prone Myocardial Perfusion SPECT (MPS) has been shown to reduce attenuation artifact in comparison to supine only MPS in mixed gender populations with varying risk for coronary artery disease. The aim of this study is to determine whether the additional prone MPS has an advantage over the supine only MPS in determining the diagnostic value of myocardial perfusion SPECT inpatient with known and unknown coronary artery disease.
Material and methods: This prospective study was performed on 93 patients, divided into two major group’s patients with known coronary artery disease and without known coronary artery disease. The duration of this study was 06 months including 03 months for clinical follow up? All patients who were assessed using standard stress supine protocol in addition to stress prone included who were observed either inferior, anterior or antero-septal wall perfusion defect in the stress supine study and they were underwent stress prone using LHC as gold standard evaluating coronary artery disease.
Results: Total n=93 patients were enrolled in this prospective study and divided into two main categories. Group I (n=29) included 31% of study population with known coronary artery disease and group II (n=64) comprises of 69% of study population with no prior history of coronary artery disease. Chi-Square (Pearson) test was applied collectively on both group I and II for statistical analysis which revealed p value of “0.005”. Sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy of prone stress MPS in group I was calculated as 92%, 80%, 96%, 67% and 90% while in group I these values were 86%, 81%, 80%, 87% and 83.3% respectively. The combined sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy of prone stress was 89.5%, 81%, 89.5%, 81% and 86.4%.
Conclusion: It is concluded that the addition of prone MPS with supine MPS overcomes soft tissue attenuation artifact hence decreases the false positive rates and preventing unnecessary further investigations and improves diagnostic accuracy.

Introduction: With the improvement in prognosis for patients with breast cancer, reducing long-term toxicity from treatment has become increasingly important. Left breast Radiotherapy (RT usually results in higher dose delivery to the heart and lungs, which are treated as Organs at Risk (OAR. Heart irradiation increases the risk of radiation induced heart disease and major coronary artery disease in long term survivors.

Material and methods: After obtaining informed consent, 50 patients were enrolled in the study between October 2020 and February 2021. Two scans were performed on each patient, one in Free Breathing (FB) and one using Deep Inspiratory Breath Hold technique (DIBH). Contouring of target volume and Organ at Risk (OAR) were performed on both scans. Dose Volume Histograms (DVH) was generated for both scans for plan evaluation. Dose parameters were calculated and compared to assess doses to heart and lungs. In addition, anatomical parameters including Maximum Heart Distance (MHD), Haller Index (HI), Central Long Distance (CLD), chest wall separation (CWS), Heart Chest Distance (HCD), Lung Volume Difference (LVD), and Cardiac Contact Distance (CCD) in axial and parasagittal planes were also studied for impact on doses to heart and lung.

Results: The reduction in mean doses using DIBH was statistically significant for both heart and lung. Overall, the mean heart dose in FB was 5.60 ± 2.20 and in DIBH it is 2.50 ± 1.24 leading to a difference of 3.4 Gy.

About 17 patients (34% failed to attain a difference of ≥2 Gy with DIBH scans. This difference was persistent and significant in V10, V30, V35 of heart. Similarly, mean left lung dose reduction of 4.89 Gy was seen from 9.42 ± 2.80 in FB to 4.53 ± 2.20 using DIBH scan with statistically significant (p value=<0.05. Overall, V₂₀ V₅ and V₁₀ of both lungs showed no statistical difference in either group (FB and DIBH, respectively. On contrary to this, the impact of DIBH dose reduction was more pronounced in V₂₀ and V₃₀ of left lung and less marked in V₅ and V₁₀. The mean differences in different anatomical parameters between FB and DIBH scan were significant for all stated parameters except chest wall separation (FB=20.35 cm, DIBH=20.55 cm, p-value=0.68. The moderate correlation between the anatomical parameters and mean heart dose reduction was statically significant for CLD (r=-0.36, p- value 0.01, MHD (r=-0.40, p-value=0.007, HCD (r=0.50, p-value=0.001, CCDps (r=-0.43, p-value=0.002 while the rest of the parameters including CCDax, LVD, CWS and Haller index showed weak correlation with outcome variable. The Multivariate regression analysis concluded HCD (β=2.02 (CI=1.14-2.89),p -value=0.001)a nd CLD (β-1.499 (CI=-2.448-0.549),p - value=0.003 two variables that independently predict mean heart dose reduction for patients undergoing DIBH based left sided breast radiotherapy.

Conclusion: DIBH is a sublime technique and it is cost effective if used in suitable cohorts of patients. To improve selection criteria, HCD and CLD can be used as suitable anatomical predictors for reduction in mean doses to organs at risk.