No abstract

Purpose: Respiratory-induced tumor motion is a major challenge in lung cancer (LC) radiotherapy. Four-dimensional computed tomography (4D-CT) using a maximum intensity projection (MIP) dataset is a commonly used and time-efficient method to generate internal target volume (ITV). This study compared ITV delineation using MIP or tumor delineation on all phases of the respiratory cycle. Materials and Methods: Thirty consecutive patients of LC who underwent 4D-CT from January 2014 to March 2017 were included. ITV delineation was done using MIP (ITVMIP) and all ten phases of the respiratory cycle (ITV10Phases). Both volumes were analyzed using matching index (MI). It is the ratio of the intersection of two volumes to the union of two volumes. A paired sample t-test was used for statistical analysis, and P < 0.05 was considered statistically significant. Results: The mean ± standard deviation volume of ITV10Phases was significantly larger compared to ITVMIP (134 cc ± 39.1 vs. 113 cc ± 124.2, P = 0.000). The mean MI was 0.75 (range 0.57–0.88). The mean volume of ITV10Phases not covered by ITVMIP was 26.33 cc (23.5%) and vice versa was 5.51 cc (6.1%). The mean MI was 0.73 for tumors close to the mediastinum, chest wall, and diaphragm. MI was not different between tumors ≤5 cm and >5 cm. The average time required for delineation was 9 and 96 min, respectively. The center of mass of two ITVs differed by 0.01 cm. Conclusion: ITV using MIP is significantly smaller and may miss a tumor compared to ITV delineation in 10 phases of 4D-CT. However, the time required is significantly less with MIP. Caution should be exercised in tumors proximity to the mediastinum, chest wall, and diaphragm.

Background: Patients with lung cancer and co-existing interstitial lung disease (ILD) are at increased risk of treatment-related toxicity after both surgery and radiotherapy. A care path was implemented at our institution for patients presenting to the lung tumor board with a possible ILD, and we report on our experience using this structured approach. Methods: Since 2015, patients with possible lung cancer and ILD were referred to the general ILD clinic for assessment. In 2017, a dedicated ILD lung tumor board was established in order to facilitate quick assessment of treatment-related risks. An ethicsapproved institutional database containing details of all these patients was accessed. Results: 24 patients with lung tumors and a co-existing ILD were identified (Table ). The mean interval between referral to, and consultation at our ILD-board was 2 weeks. A prior diagnosis of ILD was available in 9 of 17 (53%) patients, but review led to a reclassification of the ILD subtype in 8 of the former. Treatments for lung cancer included radiotherapy alone (n ¼ 14), surgery (n ¼ 6), sequential chemoradiation (n ¼ 3), and concurrent CRT followed by salvage surgery (n ¼ 1). 6 patients developed progression of ILD after radiation; of these, 2 had received nintedanib during treatment. One patient died because of progressive ILD and in another 3 patients ILD-related deaths could not be excluded. Conclusions: A dedicated care path for ILD patients resulted in a fast evaluation of lung cancer patients. A previous ILD-diagnosis was revised in a majority of patients, a process which can allow for a better understanding of treatment-related risks in different subgroups of ILD patients, and also assess the role of ILD-directed therapies.

Aim: To evaluate clinically pertinent skin dose and volume parameters for the development of toxicities following accelerated partial breast irradiation (APBI). Methods: Three skin structures of various thicknesses inside the body (2 mm, 3 mm, 4 mm) were contoured over the treated breast retrospectively in a cohort of 62 women who underwent APBI using multi-catheter interstitial brachytherapy. The correlation statistics between the various skin structures and acute and late skin sequelae were evaluated using the Mann–Whitney U test and receiver-operating characteristic analysis. A p-value of <0·05 was considered significant. Results: At a median follow-up period of 54 months (range: 28–86), a significant correlation was seen between dose received by 0·2 (D0·2) cc of skin 4 mm inside the body as well as volume receiving 100% dose (V100) of skin 3 mm inside the body with cosmesis at 2 years and at last follow-up. The threshold for the two parameters for prediction of excellent or good cosmesis was 90% of the prescribed dose and 0·05 cc, respectively. No significant dosimetric or volumetric correlation was seen with other sequelae like wound dehiscence, fat necrosis, telangiectasia and atrophy. Conclusion: The results of this study support the use of dose and volumetric indices of the sub-volumes of the skin for correlation with clinical endpoints. However, the same should be validated prospectively in a larger cohort of women undergoing breast brachytherapy.