3D Conformal Radiotherapy Research Articles

Revalidation of Proactive Gastrostomy Tube Placement Guidelines for Head and Neck Cancer Patients Receiving Helical Intensity-Modulated Radiotherapy

The Royal Brisbane and Women’s Hospital (RBWH) Swallowing and Nutrition Management Guidelines for Patients with Head and Neck Cancer were developed to enable evidence-based decision-making by the Head and Neck Multidisciplinary Team (H&N MDT) regarding enteral nutrition support options. The purpose of this study was to revalidate these guidelines in a cohort of patients receiving helical intensity-modulated radiotherapy (H-IMRT) compared to a historical cohort who received primarily 3D-conformal radiotherapy. Eligible patients attending the RBWH H&N MDT between 2013 and 2014 (n = 315) were assessed by the guidelines, with high-risk patients being recommended proactive gastrostomy tube placement. Data were collected on guideline adherence, gastrostomy tube insertions, the duration of enteral tube use and weight change. Sensitivity, specificity and positive predictive and negative predictive values were calculated and compared with the historical cohort. Overall guideline adherence was 84%, with 60% and 96% adherence to the high-risk and low-risk pathways, respectively. Seventy patients underwent proactive gastrostomy tube placement (n = 62 high-risk; n = 8 low-risk). Validation outcomes were sensitivity 73% (compared to 72%) and specificity 86% (compared to 96%). The guidelines yielded a high sensitivity and specificity, remaining valid in a cohort of patients treated with H-IMRT. Further studies are recommended to improve the sensitivity and understand the decrease in specificity in order to make ongoing guideline improvements.

PDOC-05 MULTIPLE ISOCENTRE VMAT PLANNING FOR PAEDIATRIC CRANIOSPINAL IRRADIATION USING THE HALCYON LINEAR ACCELERATOR

Abstract Paediatric brain tumours constitute the leading cause of cancer specific deaths worldwide. Many patients require craniospinal irradiation (CSI), one of the most technically demanding techniques in radiotherapy. Many LMIC centres have installed Varian Halcyon® linear accelerators and require a technique to execute CSI safely. This study evaluates a multiple isocentre VMAT planning strategy for CSI. The Halcyon is a ring based linac with a single 6MV flattening filter free (FFF) photon beam, a stacked and staggered double MLC for beam shaping and modulation, and no movable collimator jaws. Multiple isocentres are required for treatment fields longer than 28 cm. Paediatric CSI requires dose to be delivered to the entire thecal sac incorporating whole brain as well as entire spinal cord, resulting in long planning target volumes. In addition to the length of the treatment field, CSI treatments are complex due to the change in geometry of the target and the patient body over the length of the treatment field. Traditional 3D conformal radiotherapy techniques (3DCRT) require multiple isocentres with field matching and junction feathering. VMAT offers an alternative, but also require multiple fields to achieve coverage. A Halcyon based three isocentre VMAT technique was investigated and evaluated according to the QUANTEC criteria. Portal dosimetry quality assurance was performed on all fields to ensure they were clinically deliverable. High quality paediatric CSI VMAT treatments can be delivered on the Halcyon, using three isocentres with automatic feathering applied in field overlap regions. Two full arcs and one support arc were used for the brain area, with two posterior partial arcs per spine isocentre, each covering a total of 140 degrees posteriorly to limit integral dose and dose to the lungs and kidneys. Imaging and setup is required for every isocentre further than 8cm/10cm (Halcyon V2/V3 respectively) from the previous isocentre.

Reduced-dose radiotherapy for stage IE gastric mucosa-associated lymphoid tissue lymphoma: a multi-institutional prospective study (KROG 16–18)

PurposeDefinitive radiotherapy (RT) of 30 Gy or higher is commonly recommended to treat Helicobacter pylori-independent gastric mucosa-associated lymphoid tissue (MALT) lymphoma with an excellent disease control rate. However, the efficacy of reduced-dose RT has not yet been evaluated in a prospective cohort study. This multi-institutional study aimed to determine the role of reduced-dose RT in the treatment of stage IE gastric MALT lymphoma. MethodsBetween March 2017 and June 2022, 62 patients with histologically confirmed stage IE gastric MALT lymphoma without evidence of H. pylori infection were enrolled. The patients were treated with reduced-dose RT at a total dose of 24–25.5 Gy to the entire stomach. The response to therapy was evaluated by endoscopy with a biopsy of suspicious lesions if necessary. The primary endpoints were 6-month complete remission (CR) and local failure-free survival (LFFS). ResultsAmong 62 patients, 32 (51.6%) were previously treated for H. pylori eradication. Radiotherapy was delivered using 3D-conformal (n=20, 32.3%) or intensity-modulated radiotherapy (n=42, 67.7%). The median follow-up duration was 34.5 months (range, 9.6–68.8 months). The 6-month CR rate was 96.7%. The 5-year LFFS and progression-free survival rates were 92.0% and 90.4%, respectively. None of the patients experienced grade 3 or worse acute toxicities, and grade 2 acute toxicities were reported in 17 patients (27.4%). ConclusionReduced-dose RT exhibited excellent response rates in stage IE gastric MALT lymphoma, comparable to historical controls of standard dose (≥ 30 Gy) radiotherapy, with a minimal toxicity profile. Current prospective evidence strongly supports the use of definitive radiotherapy (24–25.5 Gy) for the treatment of H. pylori-independent stage IE gastric MALT lymphoma.

Evaluating the Effects of Prostate Radiotherapy Intensified with Pelvic Nodal Radiotherapy and Androgen Deprivation Therapy on Myelosuppression: Single-Institution Experience.

Prostate cancer (PCa) management commonly involves the utilization of prostate radiotherapy (PRT), pelvic nodal radiotherapy (PNRT), and androgen deprivation therapy (ADT). However, the potential association of these treatment modalities with bone marrow (BM) suppression remains inadequately reported in the existing literature. This study is designed to comprehensively evaluate the risk of myelosuppression associated with PRT, shedding light on an aspect that has been underrepresented in prior research. We conducted a retrospective analysis of 600 patients with prostate cancer (PCa) treated with prostate radiotherapy (PRT) at a single oncology center between 2007 and 2017. Patients were categorized into four cohorts: PRT alone (n = 149), PRT + ADT, (n = 91), PRT + PNRT (n = 39), and PRT + PNRT + ADT (n = 321). To assess the risk of myelosuppression, we scrutinized specific blood parameters, such as hemoglobin (HGB), white blood cells (WBCs), neutrophils (NEUT), lymphocytes (LYM), and platelets (PLT) at baseline, mid-treatment (mRT), immediately post-RT (pRT), 1 month post-RT (1M-pRT), and 1 year post-RT (1Y-pRT). The inter-cohort statistical significance was evaluated with further stratification based on the utilized RT technique {3D conformal radiotherapy (3D-CRT), and intensity-modulated radiation therapy (IMRT)}. Significant statistical differences at baseline were observed in HGB and LYM values among all cohorts (p < 0.05). Patients in the PRT + PNRT + ADT cohort had significantly lower HGB at baseline and 1M-pRT. In patients undergoing ADT, BMS had a significant impact at 1M-pRT {odds ratio (OR) 9.1; 95% Confidence Interval (CI) 4.8-17.1} and at 1Y-pRT (OR 2.84; CI 1.14-7.08). The use of 3D-CRT was linked to reduced HGB levels in the PRT + PNRT + ADT group at 1 month pRT (p = 0.015). Similarly, PNRT significantly impacted BMS at 1M-pRT (OR 6.7; CI 2.6-17.2). PNRT increased the odds of decreased WBC counts at 1Y-pRT (OR 6.83; CI: 1.02-45.82). Treatment with any RT techniques (3D-CRT or IMRT), particularly in the PRT + PNRT and PRT + PNRT + ADT groups, significantly increased the odds of low LYM counts at all time points except immediately pRT (p < 0.05). Furthermore, NEUT counts were considerably lower at 1M-pRT (p < 0.05) in the PRT + PNRT + ADT group. PLT counts were significantly decreased by PRT + PNRT + ADT at mRT (OR 2.57; 95% CI: 1.42-4.66) but were not significantly impacted by the RT technique. Treatment with PRT, ADT, PNRT, and 3D-CRT is associated with BMS. Despite this statistically significant risk, no patient required additional interventions to manage the outcome. While its clinical impact appears limited, its importance cannot be underestimated in the context of increased integration of novel systemic agents with myelosuppressive properties. Longer follow-up should be considered in future studies.

Exploring the impact of field shape on predicted dose distribution in breast cancer patients using deep learning in radiation therapy

BackgroundGeometrical information such as field shape is essential for dose calculation in radiation therapy. However, new methods of dose prediction based on deep learning only use CT images and contouring of patients. The aim of this study is to develop a deep learning method for three-dimensional dose prediction for breast cancer radiotherapy using field shape as well as CT and contouring images of patients. MethodsA total of 150 breast cancer patients' data treated with 3D conformal radiation therapy (CRT) technique were used to train and test 3D-U-Res-F-Net model. The model inputs were CT images, patients' contouring and field shape. The network output was the corresponding the patients’ dose distribution. Then, the dosimetric parameters extracted from the dose volume histograms related to the planned and predicted dose distributions were compared and were statistically analysed with the paired-samples t-test. These parameters include Dmean and Dmax for planning target volume and organs at risk, D95%, D50%, V47.5Gy for PTV, V30Gy and V25Gy for heart and V20Gy for left lung. The gamma index with 3%/3 mm criteria was calculated for PTV and OARs. ResultsThe average absolute difference of the Dmean relative to the prescribed dose for the PTV, heart, left lung, right lung and spinal cord were 1.37 ± 0.4%, 2.02 ± 2%, 2.12 ± 1%, 0.37 ± 0.3% and 0.41 ± 0.3%, respectively. The average absolute difference of the Dmax relative to the prescribed dose for the PTV and OARs varied from 0.23 ± 0.2% to 2.04 ± 2%. The 3D gamma pass rate with 3mm/3% criteria for planning target volume, heart, left lung, right lung, spinal cord and body were 89 ± 3%, 91 ± 5%, 93 ± 5%, 99 ± 3%, 99 ± 1% and 96 ± 2% respectively. ConclusionsThe results of the proposed model demonstrate that there is no significant difference between the predicted and planned dose distributions. The deep learning model can directly predict the 3D dose distribution faster than treatment planning systems. Further studies with more patients and on other cancer sites are essential to fully validate the proposed method.

Analisis Distribusi Dosis pada Treatment Planning System Pasien Kanker Payudara dengan Sumber Foton 6 MV pada Instalasi Radioterapi Rumah Sakit X

The internship at X Hospital aimed to gain practical experience as a medical physicist over two months, particularly in the treatment planning system activities in the radiotherapy unit. Additionally, this internship aimed to evaluate the Dose Volume Histogram (DVH) and analyze the effectiveness of the isodose lines. The treatment planning system is a simulation of cancer or tumor treatment using radiation with 3D conformal radiotherapy (3D-CRT) techniques. The patient study object was a woman with post-mastectomy breast cancer who was to undergo adjuvant curative therapy. The prescribed dose was 50 Gy, divided into 25 fractions, using a 6 MV photon source. The irradiation was conducted with four fields, gantry angle 129° with collimator angle 270°, 310° with collimator angle 90°, 130° with collimator angle 0°, and 270° with collimator angle 0°, field size 14 x 14 cm, and irradiation distance of 100 cm. The TPS simulation results indicated that the dose received by the Planning Target Volume (PTV) covered more than 90% of the target volume (special treatment), while the dose received by the Organ at Risk (OAR) tended to be below the threshold limit, and the isodose lines ensured optimal radiation dose distribution to the breast cancer target area. This was demonstrated by the DVH curve.

Comparison of Photon Dose Distribution in Breast Cancer Using 3DCRT and Half Beam Techniques

Radiotherapy planning can be done with 3D Conformal Radiotherapy (3DCRT) and Half Beam. The success of radiotherapy planning is considered by comparing the isodose curve, Dose Volume Histogram (DVH), Organs At Risk (OAR), Homogeneity Index (HI), and Conformity Index (CI) obtained by the 3DCRT and Half Beam techniques. This study used data from 5 patients at the Radiotherapy Installation at A.W. Hospital. Sjahranie Samarinda with radiation planning of 5000 cGy (25×2 Gy) for breast cancer. The two radiation plans used gantry angles of 310˚ and 120˚. The calculated dose distribution value can be seen through the 90%, 95% PTV dose, and OAR absorbed dose. PTV doses of 90% and 95% in the 3DCRT technique covered the target well. The radiation dose values of the 3DCRT technique at PTV 90% were around 4860 cGy – 4930 cGy and PTV 95% were around 4750 cGy – 4840 cGy. Meanwhile, the Half Beam technique could not cover the target well. It was because the radiation dose values received by the Half Beam technique at 90% PTV were around 780 cGy – 4860 cGy and 95% PTV were around 2210 cGy – 5020 cGy. The OAR absorbed doses values for the 3DCRT and Half Beam techniques were still within the safe limits of tolerance according to QUANTEC. Meanwhile, the HI and CI values in the 3DCRT technique were closer to the rules of ICRU Report 83 of 2010 compared to the Half Beam technique. Therefore, from the values that have been obtained, the success rate of the radiotherapy planning process after measurements is shown in the 3DCRT technique. It has the value of more efficient dose calculations and can be used as a reference in optimizing dose distribution to patients.

Predictors of Clinical Hematological Toxicities under Radiotherapy in Patients with Cervical Cancer-A Risk Analysis.

Cervical cancer ranks third in frequency among female cancers globally and causes high mortality worldwide. Concurrent chemoradiotherapy improves the overall survival in cervical cancer patients by 6% but it can cause significant acute and late toxicities affecting patient quality of life. Whole pelvis radiotherapy doses of 10-20 Gy can lead to myelosuppression and to subsequent hematological toxicities since pelvic bones contain half of bone marrow tissue. A total of 69 patients with IB-IVB-staged cervical cancer have been included in this retrospective cohort study. We analyzed clinical adverse events and changes in blood cell counts (hemoglobin, neutrophils, leukocytes, and platelets) during radiation or chemoradiotherapy received at the Oncological Institute of Bucharest from 2018 to 2021. Decreases in hemoglobin levels of over 2.30 g/dL during treatment were associated with BMI > 23.2 kg/m2 (OR = 8.68, 95%CI = [1.01, 75.01]), age over 53 years (OR = 4.60 95%CI = [1.10, 19.22]), with conformational 3D irradiation (OR = 4.78, 95%CI = [1.31, 17.40]) and with total EQD2 of over 66.1 Gy (OR = 3.67, 95%CI = [1.02, 13.14]). The hemoglobin decrease rate of 0.07 g/dL/day was related to 95% isodose volume (OR = 18.00). Neutropenia is associated frequently with gastrointestinal side effects and with the bowel and rectal V45 isodoses (OR = 16.5 and OR = 18.0, respectively). Associations of total external and internal radiation dose with the time durations calculated from the initiation of treatment to the onset of hematological adverse reactions were also obtained. The maximum drop in leukocytes was observed before day 35 from the RT initiation in patients who underwent treatment with 3D conformal radiotherapy (OR = 4.44, 95%CI = [1.25, 15.82]). Neutrophil levels under 2.2 × 103/μL and thrombocyte levels under 131 × 103/μL during the follow-up period were associated with a total planned dose of 54 Gy to the pelvic region volume (OR = 6.82 and OR = 6.67, respectively). This study shows the existence of clinical and blood predictors of hematological adverse reactions in cervical cancer patients. Thus, patients who are in a precarious clinical situation, with low hematological values (but not yet abnormal), should be monitored during days 29-35 after the initiation of RT, especially if they are obese or over 53 years of age.

3121: Coronary arteries exposure in VMAT versus 3D conformal radiotherapy for thymic epithelial tumors

3121: Coronary arteries exposure in VMAT versus 3D conformal radiotherapy for thymic epithelial tumors

Erectile Dysfunction and Penile Bulb Dose Following Definitive Prostate Radiation Therapy

Background: Erectile dysfunction (ED) is a common side effect of prostate cancer treatment, affecting up to 50% of patients after radiation therapy. Objectives: This study aims to analyze the correlation between the dose received by the penile bulb (PB) and ED in men who underwent definitive radiation therapy for early-stage prostate cancer without androgen deprivation therapy. Methods: The study included 40 patients who received 3D conformal radiation therapy (3D-CRT) for localized prostate cancer and were reported to be potent before treatment, as determined by the International Index of Erectile Function (IIEF-15) questionnaire. The dose to the PB was measured using dose volume histograms (DVHs), and the IIEF-15 questionnaire was completed again 3 months after 3D-CRT. The Pearson correlation coefficient and linear regression test were used to examine the correlation between the ED score and PB doses. Statistical significance was considered if the P value was less than 0.05. Results: The mean age of the patients was 75.5 ± 5.70 years. The average ED score based on the questionnaire was 15 ± 10.55. Twenty percent of the patients had moderate ED, while 80% had mild ED (all patients reported a decrease in potency after 3D-CRT). However, the correlation between the ED score and the PB mean dose was not statistically significant. Conclusions: This study revealed ED in all prostate cancer patients after 3D-CRT, but no significant correlation was found between the dose received by the PB and radiotherapy-induced impotence.

Dosimetric and radiobiological advantages from deep inspiration breath-hold and free breath technique for left-sided breast radiation using 3DCRT, IMRT and Rapid Arc methods-a complete assessment.

The verification and use of the best treatment approach using 3D conformal radiation therapy (3DCRT), intensity modulated radiation therapy (IMRT) and Rapid Arc methods for left breast radiation with dosimetric and radiobiological characteristics. The use of custom-built Python software for the estimation and comparison of volume, mean dose, maximum dose, monitor units and normal tissue integral dose along with radiobiological parameters such as NTCP, tumor control probability, equivalent uniform dose and LKB's effective volume from 3DCRT, IMRT and Rapid Arc planning with deep inspiration with breath holding (DIBH) and free breadth (FB) techniques. Volume growth of three-fourth in DIBH compared with FB causes a decrease in cardiac doses and complications because the left lung expands, pulling the heart away from the chest wall and the treatment area. A tiny area of the left lung was exposed during treatment, which reduced the mean dose. There was little difference in the treatment approaches because the spinal cord was immobile in both techniques. Rapid Arc is the unmatched modality for left-sided breast irradiation with significant patient breath-hold, as shown by the comparison of dosimetric and radiobiological parameters from treatment techniques with a deep inspiration breath-hold approach.

Evaluating a hypofractionated radiotherapy schedule for prostate cancer at an institution in South Africa

Background: Hypofractionated radiotherapy (HFRT) in the treatment of prostate cancer (PCa) has logistical and cost advantages, especially in a resource constrained setting. Studies have demonstrated equivalent efficacy with HFRT schedules using Intensity Modulated Radiation Therapy (IMRT) as treatment modality. However, higher rates of acute and late gastrointestinal (GI) and genitourinary (GU) toxicity have been reported when compared to conventionally fractionated radiotherapy (CFRT). In this study, we evaluate the efficacy and toxicity rates of a HFRT schedule using 3D conformal radiotherapy (RT) as treatment modality.Aim: With this study, we aim to describe the safety and outcomes of a definitive HFRT schedule used for localised PCa. We hypothesise that there is no difference in the biochemical relapse rate and incidence rates of normal tissue toxicities between patients receiving CFRT and HFRT schedules.Setting: This RT schedule was used at Tygerberg Academic Hospital in South Africa for the treatment of localised prostate cancer.Methods: This is a retrospective study in which the records of patients diagnosed with localised PCa were reviewed. Patients were treated with either CFRT regimen to a total of 74Gy in 37 daily fractions for 5 days a week or a HFRT regimen to a total of 65Gy in 26 daily fractions for 4 days per week.Results: In all, 116 patients were included in the study with a median follow-up of 57.2 months from the start of RT. No statistically significant differences in overall survival (OS) and biochemical relapse-free survival were found between the two schedules. A significant difference in acute GI toxicity was observed, with a higher incidence noted in the HFRT schedule. No significant differences were observed in late GI toxicity or in early and late GU toxicities.Conclusion: This study observes a hypofractionated regimen using three-dimensional conformal radiation therapy (3DCRT) with similar efficacy and RT-related toxicities to CFRT.Contribution: The HFRT schedule used in this study could be useful in hospitals with limited access to resources.

Clinical Outcomes and Treatment Efficacy in Cervical Cancer Patients in the UAE: A Retrospective Cohort Study.

Background and objectives Cervical cancer remains a significant global health issue, particularly in low- and middle-income countries. While high-income countries have seen reduced incidence and mortality rates due to effective screening and HPV vaccination programs, these rates are still high in areas with limited healthcare infrastructure. In the United Arab Emirates (UAE), recent efforts are improving public health initiatives and awareness. This retrospective cohort study evaluates clinical outcomes and treatment efficacy in cervical cancer patients at a tertiary cancer center in Al Ain, Abu Dhabi. It analyzes treatment regimens, their effectiveness, and factors affecting survival, disease progression, and treatment completion. Methods and material The study included 275 cervical cancer patients treated between January 2008 and December 2021. Data were extracted from medical records, including demographic information, clinical characteristics, and treatment details. Statistical analyses, including Kaplan-Meier survival curves and Cramér's V correlation matrix, were used to evaluate survival outcomes and the relationships between various categorical variables. Results The mean age of patients was 48.88 years, with the majority being non-nationals, 221 (80.37%). Histopathologically, there were 234 (85.18%) cases of squamous cell carcinoma (SCC) and 33 (11.85%) cases of adenocarcinomas. The International Federation of Gynecology and Obstetrics (FIGO) staging indicated that 137 (49.80%) patients were in stage II and 60 (21.81%) were in stage III. Pelvic lymph node involvement was observed in 139 (50.54%) patients. The treatment modalities included surgery in 39 (14.18%) patients, 3D conformal radiotherapy (3D-CRT) in 247 (89.81%) patients, intensity-modulated radiation therapy (IMRT) in 11 (4.00%) patients, brachytherapy in 213 (77.45%) patients, and chemotherapy in 248 (90.18%) patients. The survival analysis showed no significant differences in survival among different treatment groups, as indicated by the Log-rank test (p = 0.4060). Conclusion The study highlights the demographic and clinical characteristics of cervical cancer patients in the UAE, emphasizing the prevalence of advanced-stage diagnoses and high-grade tumors. Despite significant efforts to improve screening and treatment, cervical cancer remains a concern in the UAE. The findings underscore the need for enhanced early detection and comprehensive treatment strategies. Addressing the study's limitations, such as the retrospective design and the absence of human papillomavirus (HPV) data, could further refine cervical cancer management and improve patient outcomes in future research.

Small cell cancer of the esophagus, treatment outcomes of a rare histological type

Purpose: To demonstrate treatment outcomes in two patients with small cell esophageal cancer. Cases reports. Patient M. was assigned to receive polychemotherapy (PC H) composed of etoposide 100 mg/ m2 intravenously on days 1–3 + cisplatin 80 mg/m2 on day 1, every 21 days for 6 cycles and lanreotide 120 mg subcutaneously, every 28 days, followed by chemoradiotherapy (CRT). The patient received 1 cycle of PCT , which was well tolerated. Then, the patient received a cycle of 3D-conformal radiation therapy concurrently with 2 cycles of chemotherapy: etoposide 120 mg/m2 + cisplatin 80 mg/m2. Chemoradiotherapy was well tolerated. Dysphagia regression to grade I was observed. Currently, the patient continues to receive treatment (etoposide 100 mg/ m2 intravenously on days 1–3 + cisplatin 80 mg/m2 on day 1, every 21 days for 6 cycles and lanreotide 120 mg subcutaneously, every 28 days) and tolerates it well. Patient A. was assigned to receive PCT with etoposide 120 mg/m2 + cisplatin 80 mg/m2. After 4 cycles of PCT , the follow-up CT images revealed disease progression (enlarged retroperitoneal lymph nodes). The patient underwent external bean radiation therapy to the primary tumor. Radiotherapy was relatively well tolerated. The patient underwent the course of radiation therapy relatively satisfactorily. Due to the progression of the disease, symptomatic treatment was assigned. The patient died 9 months after diagnosis. Conclusion. Small cell carcinoma of the esophagus is a rare histological type with poor prognosis. Concurrent platinum-based chemoradiotherapy allows achievement of stable disease and disease control.

Technologies of modern radiotherapy and development prospects. Quality assurance concept

At the clinic of the N.N. Blokhin National Medical Research Center of Oncology has been using the following conformal irradiation technologies for cancer patients that meet international standards for more than 13 years: 3D conformal radio therapy (3DCRT); intensity modulated radiotherapy (IMRT); volume modulated arc therapy (VMAT); stereotactic radiation technique (SRT); radiotherapy technique with breathing control, total therapeutic irradiation (TRT) technique followed by bone marrow transplantation. The technological complex with which these technologies are implemented has demonstrated an increase in the quality of radiation treatment for cancer patients. However, despite the “advancement” of technology, there are limitations in the ability to reduce dose loads on critical organs for a number of nosologies. Therefore, the prospects for the development of radiotherapy in Russia lie in the creation of several clinical centers for the use of heavy charged particles that have different physical and dosimetric characteristics and, from this point of view, carry other opportunities and prospects. There is great interest in flash therapy.

Short course irradiation in rectal cancer: Dosimetry study comparing 3D conformal radiotherapy versus intensity-modulated radiotherapy versus volumetric modulated arc therapy

The standard radiotherapy planning technique for locally advanced rectal cancer (LARC) was 3D Conformal Radiotherapy (3DCRT). Modern radiation delivery techniques, including Intensity-Modulated Radiotherapy (IMRT) and Volumetric Modulated Arc Therapy (VMAT) techniques, have been developed in recent years in terms of dose delivery to the target while minimizing the dose to the organ at risk (OAR). The objective of this study was to identify the most suitable treatment plan technique from the available options of 3DCRT, IMRT and VMAT for LARC using short course radiotherapy (SCRT). Therefore, twenty-five adult patients with LARC in the last five-year period (2017–2021) were involved in this study. For each patient, three radiotherapy treatment plans were generated for dosimetric comparison of short course irradiation (25 Gy/5 fractions, which is the new standard of care) using Varian Eclipse software to generate 3DCRT in comparison with IMRT and VMAT plans. The conformity index (CI), the homogeneity index (HI), and the organs at risk (OAR), including bladder, small bowel, and femoral heads, were compared between the three plans. The results revealed that VMAT and IMRT plans had a higher level of conformity for the planning target volume (PTV) with 0.996 and 0.994, respectively, compared to the 3DCRT planning of 0.947 (both p < 0.005). The PTV dose distribution was less homogeneous with 3DCRT than with VMAT or IMRT plans. VMAT offered superior homogeneity to IMRT and 3DCRT plans with 1.055, 1.066, and 1.089, respectively (p < 0.005). The findings showed that VMAT is superior to IMRT and 3DCRT in almost all parameters, including dose distribution conformity and homogeneity of the target volume, as well as providing better OAR sparing in LARC patients.

DIPG-59. RADIATION-INDUCED DIPG IN A CHILD PREVIOUSLY IRRADIATED FOR CRANIOPHARYNGIOMA: CASE REPORT AND LITERATURE REVIEW

Abstract BACKGROUND Radiation-induced second malignancies occur in a subset of patients following cranial radiation therapy (RT). In Craniopharyngioma (CP), adjuvant RT is commonly recommended for residual tumor or recurrence, and radiation-induced malignant gliomas (RIMGs) are rarely reported. METHODS We report a case of radiation-induced diffuse intrinsic pontine glioma (DIPG) in pediatric Craniopharyngioma and conducted a review of previously reported cases. RESULTS A 14-year-old boy presented with complaints of headaches and vomiting for 1 month; difficulty in walking, and slurred speech for 1 week, with Lansky Performance Score (LPS) of 20. Eight years before this admission, he underwent surgical excision and 3D-conformal RT for Craniopharyngioma. His recent MRI brain was suggestive of DIPG and after a multidisciplinary discussion re-irradiation (30Gy in 10 fractions) was given. He has been alive for 5 months since diagnosis with improved symptoms and LPS (70). Including the index case, 19 cases of RIMGs in CP were identified. All except one were reported from high-income countries. Only 4 involved the pons/brainstem. The median age at CP diagnosis was 7.0 years (2.0-22.0 years), and with RIMG was 18 (6.8-41.0 years). Median latency period was 10.0 years (4.5-25.0 years). The female-to-male ratio was 1.8:1. The median previous RT dose was 54.8 Gy (49.3-60.1 Gy) with 37% cases treated with 3D conformal and 37% with conventional RT (not specified in 26%). Cerebral cortex (66.6%) was the most common site for the RIMG with temporal lobe predisposition. Chemotherapy was given in 56%, surgical excision in 50% and repeat RT in 31% cases with a median survival of 4 months (0-13 months). CONCLUSION We report the first case of radiation-induced DIPG in pediatric Craniopharyngioma in an LMIC. RIMG appears to be a rare occurrence in CP and doesn’t seem to be associated with the RT type. The overall prognosis is extremely poor.

Fetal dose assessment in a pregnant patient with brain tumor: A comparative study of proton PBS and 3DCRT/VMAT radiation therapy techniques.

The treatment of brain tumors in pregnant patients poses challenges, as the out-of-field dose exposure to the fetus can potentially be harmful. A pregnant patient with prior radiation treatment was presented with a brain tumor at our clinic. This work reports on our pre-treatment study that compared fetal dose exposure between intensity-modulated proton therapy (IMPT) using pencil beam scanning (PBS) and conventional photon 3D conformal radiation therapy (3DCRT) and volumetric-modulated arc therapy (VMAT), and the subsequent pregnant patient's radiation treatment. Pre-treatment measurements of clinical plans, 3DCRT, VMAT, and IMPT, were conducted on a phantom. Measurements were performed using a device capable of neutron detections, closely following AAPM guidelines, TG158. For photon measurements, fetus shielding was utilized. On patient treatment days, which was determined to be proton treatment, shielding was used only during daily imaging for patient setup. Additionally, an in vivo measurement was conducted on the patient. Measurements showed that IMPT delivered the lowest fetal dose, considering both photon and neutron out-of-field doses to the fetus, even when shielding was implemented for photon measurements. Additionally, the proton plans demonstrated superior treatment for the mother, a reirradiation case. The patient was treated with proton therapy, and the baby was subsequently delivered at full term with no complications. This case study supports previous clinical findings and advocates for the expanded use of proton therapy in this patient population.

Radiotherapy resources in the Philippines: A 2022 update

BackgroundCancer is the third leading cause of death in the Philippines. Radiotherapy (RT) is integral to the treatment and palliation of cancer. Therefore, RT resources across the country must be surveyed and optimized. MethodsOnline surveys were sent to the heads of all 50 RT facilities in the Philippines. The survey included items regarding the facility itself, personnel, and available services. FindingsThe survey had a 98% response rate. 76% of RT facilities in the Philippines are privately owned; 12 are government/public institutions and 8 are academic centers. Over a third are in the National Capital Region; three regions are without a single RT facility. For a population of >110 million, the Philippines has 53 linear accelerators, 125 radiation oncologists, 56 residents, 114 medical physicists, 113 radiation oncology nurses, and 343 radiation therapists. Nine radiation oncology residency programs are active. All facilities are capable of 3D conformal radiotherapy, and 96% are capable of intensity modulated radiotherapy. <30% offer stereotactic radiotherapy, and <50% offer HDR brachytherapy. ConclusionWhile there has been significant expansion of RT resources over the years, RT remains inaccessible for many in the Philippines. Urgent investment in training and retaining RT personnel is needed as well. Policy summary: With its current cancer burden, the Philippines needs at least 170 linear accelerators, 300 radiation oncologists, and 150 medical physicists. Public/government cancer centers must be built, with priority given to regions without RT facilities. HDR brachytherapy and stereotactic radiotherapy services must also be expanded. A national RT task force must be created to ensure the quality, availability, and accessibility of RT in the Philippines. Further work exploring payment schemes that improve access to RT and mitigate financial toxicity is needed, as well as integration of radiation oncology providers and health policy experts into national health system decision making.

Feasibility and Toxicity of Hypofractionated Radiation Therapy in Patients Undergoing Post Mastectomy Radiation Therapy

Introduction: Post mastectomy radiation (PMRT) plays major role in breast cancer treatment. Hypofractionated radiation is a relatively newer modality. Hypofractionation is more commonly used after breast conservation surgery. Landmark trials that studied hypofractionation had fewer PMRT subjects. Here we report our study on feasibility and toxicity profile of hypofractionated PMRT. Aim: To describe the clinical and toxicity profile of patients undergoing hypofractionated 3D conformal radiation therapy in breast cancer patients. Materials &amp; Methods: This study included patients who are eligible for post mastectomy radiation therapy above 18 years planned for adjuvant PMRT (40.05Gy in 15 fractions delivered over 3 weeks in 3D conformal radiation) to the chest wall and supraclavicular nodes between April 2021 to October 2022., active lung infection, patient preference for conventional fractionation. Dosimetric parameters to target &amp; organs at risk were analyzed. Toxicities including hematologic, dermatitis, pharyngitis &amp; other were monitored. Results: Of 71 patients, 70 patients were female and 1 is male. Majority (46%) of patients belonged to 46-55 years age group. Age ranged from 34 to 85 years. Mean age is 52 years. Clinical Stage IIIA was the most common stage with 29.5% patients followed by Stage IIB with 25.3% patients. Majority received adjuvant chemotherapy (52%). Mean treatment time is 21 days. All patients completed treatment without any major complications. Follow up ranged from 17 months to 27 months. Out of 71 patients, 1 patient expired on follow up after 4 months of radiation therapy due to non cancer related cause (Chronic pancreatitis). On follow up, 3 patients had distant metastasis alone (lung, bone metastasis, brain metastases) and 1 patient had both local disease and distant metastasis. 3 patients who progressed had stage IIIC disease &amp; 1 had stage IIIB disease. The V90 to the Planned Target volume (PTV) ranged from 90.4% to 99% to right sided disease, 90.3% to 96.5% to left sided disease. Heart V17Gy ranged from 1.27% to 12.5% &amp; heart V35Gy was 0.16% to 7.2%. Dermatitis was the most common adverse effect in this study. 31 patients (43.6%) developed fatigue during treatment. They continued their daily activities without any limitations. 35 patients (49.2%) had throat pain, of which 2 patients had it in 1st week, 21 patients had it in 2nd week and 12 patients had it in 3rd week. They were treated with non opioid analgesics. Shoulder pain was observed in 10 patients (14%) during treatment. Blood parameters were monitored weekly during treatment. No changes were observed. Conclusion: Hypofractionated post mastectomy radiation therapy is well tolerated in our study group. None of them developed any major acute reactions during and post treatment in the follow up period. Patients completed their treatment without any breaks during treatment. Respiratory motion management especially left sided disease patients should be used for achieving dose constraints.