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SU‐E‐J‐217: To Determine the Gross Tumor Volume with CT Scan in End Expiration, Inspiration and All Phases of Respiration in Carcinoma Lung Patients
Author(s) -
Srivastava R,
Sharma PK,
Sharma P,
Munshi A,
Chomal M,
Laishram S,
Saini G
Publication year - 2013
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.4814429
Subject(s) - nuclear medicine , medicine , exhalation , expiration , lung , lung cancer , radiation therapy , respiratory system , radiology , pathology
Purpose: The aim of this study was to compare the delineation and treatment planning of two phase‐based (the end‐expiration and the endinspiration phases) IGTV (Internal Gross Tumor Volume) with ten‐phase based (4D) IGTV. Methods: Two patients with lung tumors at different sites were selected for the study.The location of the tumor in Patient A was at the upper lobe(attached to the chest wall) of the left lung.In patient B the location was the middle lobe of right lung.We contoured the GTV on each of the ten respiratory phases of the 4D‐CT data set.The combination of these GTVs produced the IGTV .GTV was also generated on the extreme respiratory phases 0% phase = peak inhalation, 50% phase = peak exhalation).The combination of these two GTVs produced IGTV <2Phases>.Treatment planning was done and dose to OARs were compared in both end expiration inspiration(EEI) and 4DCT study set. Results: IGTV <2Phases> (175cc)and IGTV (180 cc) for Patient A were nearly same. But for Patient B, IGTV <2Phases> (80cc) was smaller than the IGTV (181 cc).C.I.(Conformity Index) was found better in EEI and 4DCT in Patient A than in Patient B due to the limitation of the AAA algorithm in the low density region.Lung‐GTV doses were less in EEI scan than in 4DCT for Patient B whereas it was the same for EEI and 4DCT in Patient A. Conclusion: The study shows the patients with tumor in upper lobe have no difference in tumor coverage and OARs sparing in the EEI and 4DCT. However,tumors in middle lobe have a greater excursion during respiration and hence greater all phase IGTV.We suggest performing a 4D scan and EEI scan both,for these categories of patients in order to include the tumor excursion due to breathing. Conflict of Interest: Nil; Funding Support: Required if possible