Mean Dose Research Articles

Fractal Analysis of Mandible in Panoramic Radiographs of Patients Received Radiotherapy for Nasopharyngeal Carcinoma

PurposeThis study aimed to assess the impact of radiotherapy on the internal structure complexity of mandibular cortical and trabecular bone and to determine the duration required for a return to healthy values post-radiotherapy. Materials and MethodsPanoramic radiographs from patients undergoing radiotherapy for nasopharyngeal carcinoma were analyzed before and after treatment. Four groups were formed based on post-radiotherapy radiography timing (0-6 months, 6-12 months, 12-24 months, and 24-36 months), comprising a total of 59 cases and 118 radiographs. Fractal analysis was conducted on four bilateral regions (ROI) in both trabecular and cortical bone on each radiograph. Additionally, measurements of inferior alveolar canal width and mandibular cortical width were performed. Mean and maximum radiation dose values to the mandible were measured, and their correlation with changes in fractal dimension, inferior alveolar canal width, and mandibular cortical width values was assessed. ResultsFractal dimension values in regions over trabecular bone showed a statistically significant decrease in all groups, although no significant difference was observed among the four groups. In ROI-4 from cortical bone, a significant fractal dimension decrease was noted in all groups except the 0-6 month group. The magnitude of fractal dimension decrease was higher in the 12-24 and 24-36 month groups compared to the 0-6 month group. inferior alveolar canal width and mandibular cortical width values significantly decreased post-radiotherapy in all groups, with a consistent decrease across the groups. ConclusionsRadiotherapy induces a reduction in the internal complexity of trabecular and cortical bone structures in the mandible. Osteoradionecrosis risk persists even three years post-radiotherapy, suggesting a cautious approach to interventional procedures on the bone.

Correlation of dynamic blood dose with clinical outcomes in radiotherapy for head-and-neck cancer

Background and purposeRadiation-induced lymphopenia (RIL) during cancer radiotherapy is receiving growing attention due to its association with adverse clinical outcomes. Correlations between RIL and poorer locoregional control (LRC), distant-metastasis-free survival (DMFS), and overall survival (OS) have been demonstrated across multiple treatment sites. Estimates of radiation delivered to circulating blood or lymphocytes have been shown to be correlated with severe RIL. This study aims to evaluate whether blood dose estimates are equally correlated with patient outcomes directly. Materials and methodsFor 298 head-and-neck cancer patients, blood dose was estimated via the total body dose (Dbody), a static blood dose model considering the mean dose to relevant organs and tissues (Dstatic), and a dynamic model which further included temporal aspects such as blood flow and treatment delivery time (Ddynamic). The latter utilized hematological dose (HEDOS), an open-source computational tool for blood dose simulations. Survival analysis was performed to evaluate potential correlations between blood dose and LRC, DMFS, and OS. ResultsMultivariable Cox regression analysis found a statistically significant (p < 0.05) correlation between various dynamic blood dose metrics and clinical outcomes. Dbody and Dstatic did not correlate with any of the outcomes considered. ConclusionA statistically significant correlation between the dynamic blood dose model and adverse clinical outcomes was observed. During multivariable regression analysis, neither static blood dose model exhibited a statistically significant correlation with any of the outcomes studied.

Is the IROC H&N credentialing phantom an effective surrogate for different anatomical sites?: Using IROC's H&N phantom for various sites

PURPOSEThe IROC head and neck phantom is used to credential institutions for IMRT delivery for all anatomical sites where delivery of modulated therapy is a primary challenge. This study evaluated how appropriate the use of this phantom is for varied clinical anatomy by evaluating how closely the IROC head and neck phantom described clinical dose errors from beam modeling compared to various anatomical sites. METHODSThe MLC offset, transmission, PDD and seven additional beam modeling parameters for a Varian accelerator were modified in RayStation to match community data at the 2.5, 25, 50, 75 and 97.5 percentile levels. Modifications were evaluated on 25 H&N phantom cases and 25 clinical cases (H&N, prostate, lung, mesothelioma, and brain), generating 2,000 plan perturbations. Differences in mean dose delivered to clinical target volumes (CTV) and organs at risk (OAR) were compared between phantom and clinical plans to assess the relationship between dose deviations in phantom versus clinical CTVs, and as a function of 18 different complexity metrics. RESULTSPerturbations to MLC offset and transmission parameters demonstrated the greatest impact on dose accuracy for phantom and clinical plans (for all anatomic sites). The phantom demonstrated equivalent or greater sensitivity to these parameter perturbations when compared to clinical sites, largely aligning with treatment complexity. The mean MLC Gap best described the impact of errors in TPS beam modeling parameters in phantoms plan and clinical plans from various anatomical sites. CONCLUSIONWhen compared across various anatomical sites, the IROC H&N credentialing phantom exhibited similar or greater sensitivity to errors in the treatment planning system. As such, it is a suitable surrogate device for assessing institutional performance across various anatomical sites. If an institution successfully irradiates the phantom, that result confers confidence that IMRT to a wide range of anatomical sites can be successfully delivered by the institution.

Dose Reconstruction for Epidemiological Studies among Ukrainian Chernobyl Cleanup Workers.

The present paper provides an overview of the methods and summarizes the results of estimating radiation doses and their uncertainties for Ukrainian-American epidemiological studies among the Chernobyl (Chornobyl) cleanup workers. After the Chernobyl accident occurred on April 26, 1986, more than 300,000 Ukrainian cleanup workers took part between 1986 and 1990 in decontamination and recovery activities at the site of the Chernobyl Nuclear Power Plant. The U.S. National Cancer Institute in collaboration with the Ukrainian National Research Center for Radiation Medicine conducted several epidemiological studies in this population. An important part of these studies was the reconstruction of the study participants' radiation doses and the assessment of uncertainties in doses. A method called realistic analytical dose reconstruction with uncertainty estimation (RADRUE) was used to calculate the doses from external irradiation during cleanup missions, which was the main exposure pathway for most study participants. At the initial phase of the accident during the atmospheric releases of radioactivity from the destroyed reactor, the cleanup workers also received doses from inhalation of radionuclides. In addition, study participants received doses at their places of residence, especially those who lived in highly contaminated areas. The radiation doses estimated for 2,048 male cleanup workers included in the Ukrainian-American epidemiological studies varied widely: (i) bone-marrow doses from external irradiation in the case-control study of leukemia of 1,000 cleanup workers ranged from 3.7 × 10-5 mGy to 3.3 Gy (mean = 92 mGy); (ii) thyroid doses in the case-control study of thyroid cancer in 607 persons from all exposure pathways combined were from 0.15 mGy to 9.0 Gy (mean = 199 mGy); (iii) gonadal doses in 183 cleanup workers from all exposure pathways combined in the study of germline mutations in the offspring after parental irradiation (trio study) ranged from 0.58 mGy to 4.1 Gy (mean = 392 mGy); (iv) thyroid doses in the human factor uncertainties study among 47 persons were from 20 mGy to 2.1 Gy (mean = 295 mGy); and (v) lung doses in the study of germline genetic variants associated with host susceptibility to COVID-19 estimated for 211 cleanup workers were from 0.024 mGy to 2.5 Gy (mean = 249 mGy). Doses of female cleanup workers were much lower than those of male cleanup workers: the mean doses for female cleanup workers were 27 mGy for 34 women included in the trio study and 56 mGy for 48 women participated in the study of germline genetic variants associated with host susceptibility to COVID-19. Uncertainties in dose estimates included two components: (i) inherent uncertainties arising from the stochastic random variability of the parameters used in exposure assessment and from a lack of knowledge about the true values of the parameters; and (ii) human factor uncertainties due to poor memory recall resulting in incomplete, inaccurate, or missing responses during personal interviews with cleanup workers conducted long after exposure. This paper also discusses possible developments and improvements in the methods to assess the radiation doses and associated uncertainties for cleanup workers.

Comparative study of lidocaine- saline versus saline as washout for lumpectomy cavity on acute postoperative pain

PurposeThis study aimed to evaluate the impact of lidocaine-saline solution compared to saline alone for washing out the lumpectomy cavity, focusing on its effect on acute postoperative pain—a prevalent and significant concern among patients undergoing breast surgery. MethodsIn this comparative study, 72 patients scheduled for lumpectomy surgery were randomly assigned to either the lidocaine-saline or saline group. The lidocaine-saline group was administered a washout of the lumpectomy cavity with 2 % lidocaine at a dosage of 1.75 mg/kg in 0.9 % normal saline, whereas the saline group received a washout with an equivalent volume of 0.9 % normal saline. We recorded the participants' basic characteristics, heart rate, blood pressure, the incidence and intensity of pain (measured by the visual analogue scale), and the usage of postoperative analgesics. ResultsThe two study groups did not differ significantly in their basic characteristics, heart rate and blood pressure. The saline group had significantly higher pain intensity than the lidocaine-saline group at 30 min after surgery (4.61 vs. 2.88, P < 0.0001) and at all other time points (P < 0.001). The saline group also took the first dose of analgesics earlier than the lidocaine-saline (46.66 Vs. 170.55 min, P < 0.001) and used a significantly higher mean dose of meperidine (77.50 mg vs 33.47 mg, P < 0.001). ConclusionThe use of a lidocaine-saline wash during lumpectomy procedures can significantly reduce postoperative pain and lower the necessity for analgesics in patients who have undergone breast surgery.

Dosimetric analysis of LAD dose in left-sided breast cancer radiotherapy with deep inspiratory breath hold

Objectives To analyze the dose to the left anterior descending artery (LAD) in patients who have received radiotherapy for left breast cancer with Deep Inspiratory Breath Hold (DIBH) technique and compare it with other cardiac dosimetric parameters, as well as the accepted dose constraints. Materials and Methods 20 patients (10 prospective and 10 retrospective) were selected for this study. All patients underwent 2 non-contrast radiation planning CT scans of 2.5 mm thickness - one with DIBH and one with free breathing. Contouring was done using the Radiation Therapy Oncology Group (RTOG) guidelines. LAD was delineated and given a PRV of 3 mm and 5 mm. Dose-volume histograms (DVH) were used to obtain the data from the approved plans. Results The lung volume receiving 17 Gy in percentage, Dmean of the heart, LAD Dmean and Dmax, and the Dmean and Dmax received by 3 mm and 5 mm PRVs were both very well achieved when compared to the dose constraints given by the DBCG HYPO trial. The study found a higher correlation between the mean heart dose and the 5 mm PRV dose (R2 = 0.81 and 0.71 respectively for the mean and max dose) than the 3 mm PRV, and a positive correlation between the heart dose and LAD making it a useful structure for predicting acute cardiac events. Conclusion The study of 20 patients found that DIBH is effective to minimize cardiac dose and potentially cardiac toxicity, with heart and LAD doses being comparable or lower compared to other studies. The LAD doses recorded were significantly less than those in non-DIBH studies, demonstrating the feasibility of routine contouring and recording LAD dose in left-sided breast radiation patients. Further research is needed to determine the dosimetry and clinical consequences of the Dmean and Dmax of the 5mm PRV to the LAD.

Optimizing target and diaphragmatic configuration, and dosimetric benefits using continuous positive airway pressure in stereotactic ablative radiotherapy for lung tumors.

This study aimed to evaluate the impact of facilitating target delineation of continuous positive airway pressure (CPAP) in patients undergoing stereotactic ablative radiation therapy (SABR) for lung tumors by lung expansion and respiratory motion management. We performed a prospective single-institutional trial of patients who were diagnosed with either primary lung cancer or lung metastases and received SABR with a dose of 40 to 60 Gy in 4 fractions. Four-dimensional computed tomography simulations were conducted for each patient: once without CPAP and again with CPAP. Thirty-two patients with 39 tumors were analyzed, after the withdrawal of five patients due to discomfort. For 26 tumors separated from the diaphragm, CPAP significantly increased the superoinferior distance between the tumor and the diaphragm (5.96 cm vs. 8.06 cm; p < 0.001). For 13 tumors located adjacent to the diaphragm, CPAP decreased the overlap of planning target volume (PTV) with the diaphragm significantly (6.32 cm3 vs. 4.09 cm3; p = 0.002). PTV showed a significant reduction with CPAP (25.06 cm3 vs. 22.52 cm3, p = 0.017). In dosimetric analyses, CPAP expanded lung volume by 58.4% with a significant reduction in mean dose and V5 to V40. No more than grade 2 adverse events were reported. This trial demonstrated significant improvement of CPAP in target delineation uncertainties for lung SABR, with dosimetric benefits, a favorable safety profile and tolerability. Further investigation is warranted to explore the role of CPAP as a novel strategy for respiratory motion management.

Radiation-induced Esophagitis in Breast Cancer Patients Treated With Supraclavicular Field Irradiation.

The objective of this research was to assess the frequency and intensity of radiation-induced esophagitis in breast cancer patients treated with supraclavicular radiotherapy field irradiation. This study involved 100 patients with positive lymph nodes receiving radiotherapy to the breast or chest wall along with supraclavicular field irradiation, with toxicity levels assessed weekly. Treatment utilized the 3D conformal technique, and variables, such as mean and maximum dose to the cervical esophagus, mean dose to the entire esophagus, and length of the esophagus within the treated area were recorded. The occurrence of grade 2 or higher esophagitis was 48%, with patients facing the risk of developing such esophagitis at an average dose of 13 Gy. The probability of grade 2 esophagitis occurring at doses exceeding 13 Gy was statistically significantly higher (p<0.001) with an odds ratio of 24.4. Limiting the mean cervical esophagus dose to <13 Gy could help reduce the frequency and severity of grade 2 or higher toxicity.

Investigation of clinical and paraclinical consequences of tramadol poisoning and related factors

Tramadol, is frequently misused and leading to an increase in cases of overdose and poisoning worldwide. This study aimed to investigate the clinical and paraclinical consequences of tramadol poisoning and related factors. This was a retrospective study performed on patients with acute tramadol poisoning who were referred to the Amir Al-Momenin Hospital Emergency Department, Zabol, during 2019-2020. Patients’ socio-demographic information and clinical and paraclinical manifestations were collected in a predesigned checklist. Overall, 71 subjects were included in this study. The mean dose of tramadol was 640.14 ± 521 mg. Seizures occurred in 17 subjects that were not dose-dependent. In patients who died or were in a coma, pH, bicarbonate (HCO3 ), and oxygen saturation (O2 sat) levels decreased, while PCO2 levels increased significantly (P &lt; 0.05). The dose of tramadol used in the poisoning of this substance played no role in the course of the disease and the prognosis of patients, but low pH, HCO3 , O2 sat, and high CO2 pressure could be related to the outcome of these patients.

Phototesting for a variety of skin conditions before narrowband (TL-01) Ultraviolet-B

Background: For the majority of photo responsive skin disorders, narrowband ultraviolet-B (NBUV-B) phototherapy is currently regarded as the preferred option. The initial dosage of NBUV-B phototherapy is determined as a percentage of the minimal erythema dose (MED) at the majority of dermatology centers that offer phototherapy. This will shorten the time of therapy and lower the chance of burning while optimizing the therapeutic effect. Three times a week is the usual dosage for NBUV-B phototherapy treatment, which takes 18 to 30 sessions on average to clear the condition. For these types of treatment plans, a precise evaluation of the MED is necessary before starting treatment in order to prevent NBUV-B overdoses or underdoses. Aim: The objective of this study is to investigate the MED of 311nm NBUV-B phototherapy in a group of Libyan patients. Methods: For this prospective study, 150 patients with a range of skin conditions who saw the phototherapy unit at Bir Usta Melad Hospital of Dermatology and Venereology in Tripoli, Libya over an 8-month period were enrolled. Skin conditions include vitiligo, atopic dermatitis, and psoriasis are among those being researched. Using Fitzpatrick's questionnaire, skin types were assigned to each patient. Using a MED tester instrument (Dermalight® 80), 311 nm NBUV-B was applied to the right forearm. The test findings were recorded 24 hours later. Results: Of the patients studied, 82 (54.7%) were female and 68 (45.3%) were male. Their ages ranged from 10 to 60 years, with 30% of the sample falling between the ages of 31 and 40. The patients were clinically diagnosed with the following conditions: vitiligo 65(43.3%), psoriasis 61(40.7%), eczema 8(5.3%), pruritus 6(4%), and alopecia areata and lichen planus 5(3.3%) each. According to Fitzpatrick's categorization, the skin prototypes in the included series were 15(10%) patients of skin type III, 118(78.7%) patients of skin type IV, and 17(11.3%) patients of skin type V. Among the enrolled participants, the minimum necessary dose to elicit an erythema for NBUV-B ranged between 300 mJ/cm2 and 750 mJ/cm2, with the mean dosage was 484.7 ± 82.2 mJ/cm2. Conclusions: The average MED to 311nm NBUV-B in Libyan patients was around 500 mJ/cm2, which can be utilized to determine the initial dose and treatment regimen of phototherapy for various skin conditions.

Inverse versus convolution treatment planning algorithms for gamma knife radiosurgery.

To compare the convolution and inverse algorithm plans. The cross-sectional study was conducted from January to May 2022 at the Icon Gamma Knife Centre, Al- Taj Hospital, Baghdad, Iraq, and comprised patients with malignant and benign brain tumours who underwent gamma knife therapy. Each patient's brain was imaged using computed tomography and magnetic resonance imaging. The neurosurgeon prescribed the dose depending on the tumour volume and type, while the medical physicist generated the two plans based on inverse and convolution algorithms. The prescribed dose was delivered to 50% of the isodose line of the tumour. Each plan was evaluated with respect to tumour conformity index, coverage, gradient index, number of shots, and time of treatment. Of the 30 patients, 17(56.7%) were males and 13(43.3%) were females. The overall mean age was 46.29±15.20 years (range: 10-71 years). The mean dose delivered was 15.86±3.86Gy, and the mean number of gamma radiation shots was 12.56±6.95. There was significant difference between the two algorithm plans for all dosimetric parameters, with the inverse plan providing higher coverage and selectivity than convolution plan, but taking longer time(p<0.05), while plan was inverse plan better than convolution plan in terms of gradient and conformity (p<0.05). With more extended treatment, the inverse plan was found to have superior selectivity, coverage, gradient index and Paddick conformity index values compared to the convolution plan.

Effect of using bolus on the efficiency of the 3DCRT of the breast cancer after mastectomy.

To assess the effect of using bolus on the efficiency of three-dimensional conformation radiation treatment of breast cancer post-mastectomy. The prospective, clinical study was conducted at Al-Amal Center for Radiation Therapy and Nuclear Medicine, Iraq, from November 2020 to April 2021, and comprised patients with synchronous bilateral breast cancer with regional lymph nodes who underwent mastectomy. The three-diensional conformation radiation treatment technique was used to evaluate the dose received by the planning target volume and the organs at risk. The plans were generated using a treatment planning system, the plans were then fed into a linear accelerator. The plans had one isocenter for both breasts to avoid the errors that may cause the overlapping of the radiation fields with and without the use of bolus. Data was analysed using SPSS 24. There were 23 female patients with mean age 49.28±8.79 years (range: 35-62 years). There were 7(30.4%) females residing in rural areas, while 16(69.6%) lived in urban areas. The use of bolus increased the radiation dose coverage percentage of the planning target volume of the right (p=0.0002) and left (p=0.0164) breasts, while the right (p=0.3977) and left (p=0.7940) supraclavicular nodes were not significantly covered by the radiotherapy dose. The use of bolus showed a strong significant decrease of the mean dose that was received by the left lung (p=0.00001). Also, the use of bolus caused significant reduction in the amount of the mean scattered dose that reached the heart (p=0.00001) and larynx (p=0.00004). The use of bolus provided a complete radiotherapy dose coverage for the right and left breasts, as well as an excellent protection for the left lung, heart and larynx.

A deep learning-informed interpretation of why and when dose metrics outside the PTV can affect the risk of distant metastasis in SBRT NSCLC patients

PurposeRecent papers suggested a correlation between the risk of distant metastasis (DM) and dose outside the PTV, though conclusions in different publications conflicted. This study resolves these conflicts and provides a compelling explanation of prognostic factors.Materials and methodsA dataset of 478 NSCLC patients treated with SBRT (IMRT or VMAT) was analyzed. We developed a deep learning model for DM prediction and explainable AI was used to identify the most significant prognostic factors. Subsequently, the prognostic power of the extracted features and clinical details were analyzed using conventional statistical methods.ResultsTreatment technique, tumor features, and dosiomic features in a 3 cm wide ring around the PTV (PTV3cm) were identified as the strongest predictors of DM. The Hazard Ratio (HR) for Dmean,PTV3cm was significantly above 1 (p < 0.001). There was no significance of the PTV3cm dose after treatment technique stratification. However, the dose in PTV3cm was found to be a highly significant DM predictor (HR > 1, p = 0.004) when analyzing only VMAT patients with small and spherical tumors (i.e., sphericity > 0.5).ConclusionsThe main reason for conflicting conclusions in previous papers was inconsistent datasets and insufficient consideration of confounding variables. No causal correlation between the risk of DM and dose outside the PTV was found. However, the mean dose to PTV3cm can be a significant predictor of DM in small spherical targets treated with VMAT, which might clinically imply considering larger PTV margins for smaller, more spherical tumors (e.g., if IGTV > 2 cm, then margin ≤ 7 mm, else margin > 7 mm).

Is clinical target volume necessary for locally advanced non-small cell lung cancer treated with 4D-CT intensity-modulated radiation therapy

BackgroundA dosimetric evaluation is still lacking in terms of clinical target volume (CTV) omission in stage III patients treated with 4D-CT Intensity-Modulated Radiation Therapy (IMRT).Methods49 stage III NSCLC patients received 4D-CT IMRT were reviewed. Target volumes and organs at risk (OARs) were re-delineated. Four IMRT plans were conducted retrospectively to deliver different prescribed dose (74 Gy–60 Gy), and with or without CTV implementation. Dose and volume histogram (DVH) parameters were collected and compared.ResultsIn the PTV-g 60 Gy plan (PTV-g refers to the PTV generated from the internal gross tumor volume), only 5 of 49 patients had the isodose ≥ 50 Gy line covering at least 95% of the PTV-c (PTV-c refers to the PTV generated from the internal CTV) volume. When the prescribed dose was elevated to 74 Gy to the PTV-g, 33 of 49 patients could have the isodose ≥ 50 Gy line covering at least 95% of the PTV-c volume. In terms of OARs protection, the SIB-IMRT plan showed the lowest value of V5, V20, and mean dose of lung, had the lowest V55 of esophagus, and the lowest estimated radiation doses to immune cells (EDIC). The V20, V30, and mean dose of heart was lower in the simultaneous integrated boost (SIB) IMRT (SIB-IMRT) plan than that of the PTV-c 60 Gy plan.ConclusionsCTV omission was not suitable for stage III patients when the prescribed dose to PTV-g was 60 Gy in the era of 4D-CT IMRT. CTV omission plus high dose to PTV-g (74 Gy for example) warranted further exploration. The SIB-IMRT plan had the best protection to normal tissue including lymphocytes, and might be the optimal choice.

Online adaptive radiotherapy in stereotactic body radiotherapy for pancreatic cancer patients.

Stereotactic radiation therapy (SBRT) has emerged as a promising treatment modality for locally advanced pancreatic cancer. The aim of this study is to assess the dosimetric efficacy of online adaptive radiotherapy (ART) in comparison to image-guided radiation therapy (IGRT) for pancreatic cancer. We conducted a retrospective analysis involving 8 patients diagnosed with locally advanced pancreatic cancer. The gross tumor volume (GTV) delineates the visible extent of the tumor on imaging, while the planning tumor volume (PTV) was generated by expanding 5mm from the GTV and ensuring a 3mm distance from the small intestine, duodenum, and stomach simultaneously. Treatment planning was executed using the United Imaging Healthcare Treatment Planning System workstation. The control group underwent evaluation based on daily validated fan-beam CT (FBCT) scans, assessing both the dose delivered to actual organs at risk (OARs) and the target volume. Radiotherapy plans were developed utilizing simulation CT, and conventional radiotherapy with daily image-guided radiation therapy (IGRT) was administered using FBCT-Linac. Conversely, patients in the study group received daily validated FBCT-guided adaptive radiotherapy plans, with a focus on mean dose assessment of both the target volume and OARs. Subsequently, we compared the average outcomes of each treatment fraction between IGRT and online adaptive radiotherapy (ART). Comparison between ART and IGRT treatment plans revealed significant differences in various dosimetric parameters: For PTV: V98%: ART (96.28%) vs IGRT (89.73%), p = 0.000, V95%: ART (96.28%) vs IGRT (89.73%), p = 0.031, V90%: ART (98.58%) vs IGRT (93.65%), p = 0.000, Dmean: ART (4912.91) vs IGRT (4804.11), p = 0.000. For GTV: V100%: ART (97.96%) vs IGRT (94.85%), p = 0.314, V98%: ART (100.00%) vs IGRT (96.83%), p = 0.000, V90%: ART (100.00%) vs IGRT (97.75%), p = 0.000, Dmean: ART (4972.17) vs IGRT (4907.23), p = 0.000. For the duodenum: D0.5cc: ART (2883.92) vs IGRT (3359.35), p = 0.000, D1cc: ART (2726.32) vs IGRT (3128.66), p = 0.001, D5cc: ART (2051.96) vs IGRT (2273.93), p = 0.015, D10cc: ART (1650.73) vs IGRT (1731.74), p = 0.211. For the small bowel: D0.5cc: ART (3022.3) vs IGRT (3142.64), p = 0.037. D5cc: ART (2151.09) vs IGRT (2389.15), p = 0.043, D10cc: ART (1775.20) vs IGRT (1942.00), p = 0.079. For the stomach: D0.5cc: ART (3353.92) vs IGRT (4117.85), p = 0.000, D5cc: ART (2860.20) vs IGRT (3235.41), p = 0.000, D10cc: ART (2553.72) vs IGRT (2836.73), p = 0.000. For the Dmean of the left kidney and right kidney: Left kidney: ART (248.28) vs IGRT (239.65), p = 0.100. Right kidney: ART (314.55) vs IGRT (307.17), p = 0.345. These results suggest significant improvements in PTV coverage and sparing of OARs with ART compared to IGRT, indicating the potential of ART in optimizing treatment outcomes for pancreatic cancer patients.Compared to conventional IGRT-guided SBRT programs, ART-based SBRT for pancreatic cancer not only enhances the dose distribution to the target volume but also mitigates the radiation exposure to critical organs-at-risk (OARs) such as the duodenum, small intestine, and stomach. This approach may offer a more favorable safety profile while concurrently enhancing treatment efficacy.

LatticeOpt: An automatic tool for planning optimisation of spatially fractionated stereotactic body radiotherapy

PurposeLattice radiotherapy (LRT) is a three dimensional (3D) implementation of spatially fractionated radiation therapy, based on regular spatial distribution of high dose spheres (vertices) inside the target. Due to tumour shape heterogeneity, finding the best lattice arrangement is not trivial.The aim of this study was to develop the LatticeOpt tool to generate the best lattice structures on clinical cases for treatment planning. MethodsDeveloped in MATLAB, LatticeOpt finds the 3D-spatial configurations that maximize the number of vertices within the gross target volume (GTV). If organs at risk (OARs) are considered, it chooses the solution that minimizes the overlapping volume histograms (OVH). Otherwise, the lattice structure with the minimum Hausdorff distance between vertices and GTV boundary is chosen to avoid unpopulated regions.Different lattice structures were created for 20 patients, with (OVHopt) and without (OVHunopt) OVH minimization. Imported into TPS (Eclipse, Varian), corresponding plans were generated and evaluated in terms of OAR mean and maximum doses, GTV vertex coverage and dose gradients, as well as pre-clinical plan dosimetry. ResultsPlans based on an optimized lattice structure (OVHopt, OVHunopt) had similar dose distributions in terms of vertex coverage and gradient index score. OAR sparing was observed in all patients, with a 4 % and 9 % difference for mean and max dose (both p-values <0.01), respectively. The best vertices dimensions and their relative distances were patient dependent. ConclusionsLatticeOpt was able to reduce the time-consuming procedures of LRT, as well as to achieve standardized and reproducible results, useful for multicentre studies.

Plasma Renin: A Useful Marker for Mineralocorticoid Adjustment in Patients With Primary Adrenal Insufficiency.

Renin is a marker of blood volume. There is no consensus on the validity of plasma renin measurement for adjusting mineralocorticoid (MC) substitution in patients with primary adrenal insufficiency (PAI). This work aimed to investigate if plasma renin could be used to adjust MC substitution in patients with PAI. A total of 150 patients with at least one measurement of plasma renin followed for PAI at 2 tertiary expert centers between 2008 and 2022 were retrospectively included. As supraphysiological hydrocortisone might have additional MC activity, we integrated the individual hydrocortisone dose to obtain the MC equivalent dose (Eq-MC). Renin less than 20 mIU/L was considered oversubstituted, renin between 20 and 60 mIU/L as correctly substituted, and renin over 60 mIU/L as undersubstituted. The mean dose of fludrocortisone was 82.3 ± 46 μg/day. Plasma renin was abnormal in 56.7% of cases (7 patients oversubstituted and 78 patients undersubstituted). Abnormalities in electrolyte levels were observed in only 12.7% of patients. Plasma renin correlated negatively with sodium (P < .01) and systolic blood pressure (P = .026), and positively with potassium (P < .01). Doses changes in Eq-MC had a statistically significant effect on renin levels (P = .0037), with an increase of MC dose correlating with a decrease in renin level and vice versa; no correlation was observed using electrolytes or blood pressure. Plasma renin correlates with electrolytes and blood pressure. While dose changes significantly alter renin levels, electrolytes and blood pressure do not, suggesting that renin may provide more information about MC replacement therapy than electrolytes and blood pressure.

Patient, tumour, and dosimetric factors influencing survival in non-small cell lung cancer patients treated with stereotactic ablative body radiotherapy.

We aimed to analyse clinical outcomes of peripheral, early-stage non-small cell lung cancer (NSCLC) patients treated with stereotactic ablative body radiotherapy (SABR), and evaluate potential patient, tumour, and dosimetric variables influencing survival. Data were collected retrospectively from patients treated between September 2012 and December 2016 and followed up until January 2021. Patient demographics, tumour characteristics, SABR dosimetric parameters, and survival data were collected from electronic patient medical records. Descriptive statistics were performed, and SPSS software was used for survival analysis. Eighty-nine patients were included of whom 49.5% were male and 50.5% female. Median age was 74 years. 98.8% of patients had T1-2 tumours and 89.9% underwent 55 Gy in 5 fractions. Median overall survival time was 58.7 months. On uni- and multi-variate analysis, neither patient nor tumour variables showed association with overall survival. However, planning target volume (PTV) and minimum dose to PTV correlated with overall survival. There was a signal for association between mean lung dose and overall survival on multivariate analysis. Our long-term results show SABR is an effective treatment for peripheral, early-stage NSCLC with excellent overall survival, comparable to other series. Our study found only the PTV and minimum dose to PTV had an impact on overall survival, which demonstrates the importance of generating optimal SABR plans. Our work identified lung SABR dosimetric parameters that correlate with survival, which illustrates the importance of producing optimal lung SABR plans.

Investigate potential clinical benefits and linear energy transfer sparing utilizing proton arc therapy for hepatocellular carcinoma

PurposeTo investigate the potential clinical benefits and dose-averaged Linear Energy Transfer (LETd) sparing, utilizing proton arc plan for hepatocellular carcinoma (HCC) patients in comparison with Intensity Modulated Proton Therapy (IMPT). MethodsTen HCC patients have been retrospectively selected. Two planning groups were created: Proton Arc plans using Monaco ver. 6 and the clinical IMPT plan. Both planning groups used the same robustness parameters. The prescription dose is 67.5 Gy (RBE) in 15 fractions of the Clinical Target Volume (CTV). Robustness evaluations were performed to ensure dose coverage. Normal Tissue Complicated Probability (NTCP) model was utilized to predict the possibility of Radiation-Induced Liver Disease (RILD) and evaluate the potential benefit of proton arc therapy. LETd calculation and evaluation were performed as well. ResultsProton arc plan has shown better dosimetric improvements of most Organ-At-Risks (OARs). More specifically, the liver mean dose has been significantly reduced from 14.7 GyE to 10.62 GyE compared to the IMPT plan. The predicted possibility of RILD has also been significantly reduced for cases with a large and deep liver target where healthy liver tissue sparing is a challenge. Additionally, proton arc therapy could increase the average LETd in the target and reduce LETd in adjacent OARs. ConclusionsThe potential clinical benefit of utilizing proton arc therapy HCC varies depending on the patient-specific geometry. With more freedom, proton arc therapy can offer a better dosimetric plan quality in the challenge cases, which might not be feasible using the current IMPT technique.

Risk Stratification by Combination of Heart and Lung Dose in Locally Advanced Non-Small-Cell Lung Cancer after Radiotherapy

Background/Objectives: Despite advancements in treatment for patients with unresectable locally advanced non-small cell lung cancer (LA-NSCLC), overall survival (OS) remains poor. The specific effects of varying heart and lung doses on OS in LA-NSCLC patients have not been thoroughly investigated, especially their combined impact on survival. This study aimed to examine the impact on OS of both individual and combined heart and lung doses in patients with LA-NSCLC treated with radiotherapy over a three-year follow-up period. Methods: A total of 120 patients who received definitive radiotherapy for LA-NSCLC (stage III, 92.5%) from January 2015 to January 2020 were retrospectively reviewed. The endpoint in this study was OS. Each patient was followed for a fixed period of three years. Results: Univariate Cox regression analysis showed that OS was significantly related to mean heart dose (MHD, hazard ratio [HR], 3.4 [1.8–6.3]; p &lt; 0.001), pericardium V40 (HR, 3.2 [1.7–6.0]; p &lt; 0.001), and total lung V20 (HR, 2.6 [1.4–5.0]; p = 0.003), and these were independent predictors for worse OS in multivariate analysis. Kaplan–Meier curve analysis with log-rank tests revealed that survival was significantly worse in patients with higher MHD (p &lt; 0.001), pericardium V40 (p &lt; 0.001), and total lung V20 (p = 0.002). Combining MHD and total lung V20, and pericardium V40 and total lung V20 provided enhanced risk stratification for OS (p &lt; 0.001 for both combinations). Conclusions: The combination of heart and lung doses provided enhanced and more detailed risk stratification in prediction of OS for a fixed period of three years in LA-NSCLC patients treated with radiotherapy.