Image-guided radiation therapy in lymphoma management

Abstract

Image-guided radiation therapy (IGRT) is a process of incorporating imaging techniques such as computed tomography (CT), magnetic resonance imaging (MRI), Positron emission tomography (PET), and ultrasound (US) during radiation therapy (RT) to improve treatment accuracy. It allows real-time or near real-time visualization of anatomical information to ensure that the target is in its position as planned. In addition, changes in tumor volume and location due to organ motion during treatment can be also compensated. IGRT has been gaining popularity and acceptance rapidly in RT over the past 10 years, and many published data have been reported on prostate, bladder, head and neck, and gastrointestinal cancers. However, the role of IGRT in lymphoma management is not well defined as there are only very limited published data currently available. The scope of this paper is to review the current use of IGRT in the management of lymphoma. The technical and clinical aspects of IGRT, lymphoma imaging studies, the current role of IGRT in lymphoma management and future directions will be discussed.

Keywords: Adaptive radiation therapy; Image-guided radiotherapy; Lymphoma.

Fig. 1. IGRT with CBCT of a 74-year-old man with bulky mesenteric DLBCL. (A) CBCT is matched by fusion with the reference CT before treatment. (B) Alternatively CBCT can be matched by squares with the reference CT (purple, internal target volume; green, CBCT; pink, CT).

Fig. 2. PET-CT of recurrent DLBCL in the left inguinal nodes. (A) Coronal view and (B) axial view.

Fig. 3. Coronal views of PET-CT of a 74-year-old man with bulky mesenteric DLBCL. (A) Baseline image before chemotherapy. (B) Complete response after 3 cycles of chemotherapy.

Fig. 4. Gastric MALT lymphoma stage IEA. Internal target volume was obtained with 4D CT scan and planning target volume expansion was performed.

Fig. 5. A patient treated with consolidation radiation therapy to the upper para-aortic area and spleen after complete response to chemotherapy for DLBCL. (A) IGRT-IMRT and respiratory gating show very conformal isodose lines around the target with sparing of the heart and kidneys. (B) Respiratory gating takes advantage of increased separation between the heart and spleen with inspiration. (C) Dose-volume histogram shows minimal dose to the heart and other organs at risk.