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PURPOSE: To evaluate the quality of fully automated stereotactic body radiation therapy (SBRT) planning based on volumetric modulated arc therapy, which can reduce the reliance on historical plans and the experience of dosimetrists. METHODS: Fully automated re-planning was performed on twenty liver cancer patients, automated plans based on automated SBRT planning (ASP) program and manual plans were conducted and compared. One patient was randomly selected and evaluate the repeatability of ASP, ten automated and ten manual SBRT plans were generated based on the same initial optimization objectives. Then, ten SBRT plans were generated for another selected randomly patient with different initial optimization objectives to assess the reproducibility. All plans were clinically evaluated in a double-blinded manner by five experienced radiation oncologists. RESULTS: Fully automated plans provided similar planning target volume dose coverage and statistically better organ at risk sparing compared to the manual plans. Notably, automated plans achieved significant dose reduction in spinal cord, stomach, kidney, duodenum, and colon, with a median dose of D2% reduction ranging from 0.64 to 2.85 Gy. R50% and Dmean of ten rings for automated plans were significantly lower than those of manual plans. The average planning time for automated and manual plans was 59.8 ± 7.9 min vs. 127.1 ± 16.8 min (- 67.3 min). CONCLUSION: Automated planning for SBRT, without relying on historical data, can generate comparable or even better plan quality for liver cancer compared with manual planning, along with better reproducibility, and less clinically planning time.

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PURPOSE: To evaluate the added value of diffusion-weighted imaging (DWI) to T2-weighted imaging (T2WI) for improved identification of pelvic lymph nodes (LN) by radiation oncologists. METHODS/PATIENTS: This retrospective study included 20 patients with histopathologically proven node-negative prostate cancer. All patients underwent 3T-MRI of the prostate; matched axial T2WI and DWI sequences were assessed by an experienced uro-radiologist as the reference standard. Consultant and specialist registrar radiation oncologists were asked to identify all LN first on T2WI alone (read 1) and then on T2WI and DWI combined (read 2); LN were measured in size and divided into true positives (TP), false positives (FP) and false negatives (FN). Sensitivity, positive predictive value (PPV) and false negative rate (FNR) were then calculated and compared using Pearson's Chi square test. RESULTS: A total of 177 LN comprised the reference standard. 16 TP, 16 FP and 161 FN LN (sensitivity 9.0%, PPV 50.0%, FNR 91.0%) and 124, 15 and 53 LN (70.1%, 89.2%, 30%) were identified by reader 1 on reads 1 and 2, respectively; χ2 (2, N = 385) = 137.8, p < 0.0001. 27, 21 and 150 LN (15.3%, 56.3%, 84.8%) and 120, 13 and 57 LN (67.8%, 90.2%, 32.2%) were identified by reader 2 on the two reads; χ2 (2, N = 388) = 102.4, p < 0.0001. CONCLUSIONS: Adding DWI to T2WI significantly improved identification of pelvic LN by radiation oncologists and can therefore be regarded as a useful LN contouring technique for RT planning in pelvic malignancies.

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PURPOSE: To identify the main difficulties in postoperative clinical target volume (CTV) delineation in gastric cancer (GC). METHODS: Before and after a training course, 20 radiation oncology residents were asked to delineate the CTV for the postoperative GC case on four computed tomography scans: dome of the diaphragm, anterior abdominal wall, duodenal stump and porta hepatis level, and to determine the lower CTV border. CTV volume was reconstructed from requested planar contours. Area of intersection (AI) for each requested scan and volume of intersection (VI), defined as the overlap of delineated area/volume with respective reference area (RA)/reference volume (RV) proposed by the senior radiation oncologist, were computed. The degree of agreement between the reference and participants' contours was quantified using the Concordance Index (CI): AI/RA × 100% or VI/RV × 100%. The lower CTV border was analyzed separately. Pre- and post-training CIs were compared. A questionnaire investigated the difficulties with contouring. RESULTS: Mean CI value was the lowest for the dome of the diaphragm (24% pre-training, 35 % post-training) and for the duodenal stump (49% pre-training, 61% post-training). Mean CI for the CTV volume was 49% pre-training and 59% post-training, p = 0.39. Mean distance from the reference to the participants' lower CTV borders was 2.73 cm pre-training and 2.0 cm post-training, p = 0.71. In a questionnaire, 75% of respondents indicated the elective nodal area as the main difficulty. CONCLUSIONS: Delineation of the dome of the diaphragm and the duodenal stump, as yet not recognized as the source of variation, should be addressed in the international consensus guidelines and clarified.

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OBJETIVO: Avaliar os limites de campo padronizados para radioterapia de neoplasia maligna de colo uterino com o uso de ressonância magnética e verificar a importância deste exame na redução de possíveis erros de planejamento com técnica convencional. MATERIAIS E MÉTODOS: Foram analisados, retrospectivamente, exames de ressonância magnética do planejamento de 51 pacientes tratadas devido a neoplasia de colo uterino. Os parâmetros estudados foram limites anterior e posterior no corte sagital. RESULTADOS: Observou-se, no corte sagital das ressonâncias magnéticas, que o limite de campo anterior apresentou-se inadequado em 20 (39,2 por cento) pacientes e que houve perda geográfica em 37,3 por cento dos casos no limite posterior. A inadequação de ambos os limites de campo não se relacionou com parâmetros clínicos como idade das pacientes, estadiamento, tipo e grau histológico. CONCLUSÃO: A avaliação dos limites de campo padronizados pela literatura com o uso de ressonância magnética mostrou altos índices de inadequação dos limites do campo lateral, assim como a importância do uso deste exame no planejamento radioterápico de pacientes portadoras de câncer de colo uterino com a finalidade de reduzir a perda geográfica no volume alvo de tratamento.

OBJECTIVE: To evaluate, by means of magnetic resonance imaging, the standardized field borders in radiotherapy for malignant neoplasm of uterine cervix, and to determine the role of this method in the reduction of possible planning errors related to the conventional technique. MATERIALS AND METHODS: Magnetic resonance imaging studies for planning of treatment of 51 patients with uterine cervix cancer were retrospectively analyzed. The parameters assessed were the anterior and posterior field borders on sagittal section. RESULTS: The anterior field border was inappropriate in 20 (39.2 percent) patients and geographic miss was observed in 37.3 percent of cases in the posterior border. The inappropriateness of both field borders did not correlate with clinical parameters such as patients' age, tumor staging, histological type and degree. CONCLUSION: The evaluation of standardized field borders with the use of magnetic resonance imaging has demonstrated high indices of inappropriateness of the lateral field borders, as well as the relevant role of magnetic resonance imaging in the radiotherapy planning for patients with uterine cervix cancer with a view to reduce the occurrence of geographic miss of the target volume.

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