ABSTRACT
BACKGROUND: Deep-inspiration breath-hold (DIBH) reduces radiation dose to the heart in patients undergoing locoregional breast radiotherapy. In the context of tangential irradiation of the breast/ chest wall, a voluntary breath hold (vDIBH) technique has been shown to be as reproducible as a machine-assisted breath hold technique using the active breathing co-ordinator (ABC™, Elekta, Crawley, UK, ABC_DIBH). This study compares set-up reproducibility for vDIBH versus ABC_DIBH in patients undergoing volumetric-modulated arc radiotherapy (VMAT) for breast cancer, both with and without wax bolus. METHOD: Patients with breast cancer requiring pan regional lymph node VMAT +/- wax bolus in breath-hold were CT scanned in vDIBH and ABC_DIBH. Patients were randomised to receive one technique for fractions 1-7 and the other for fractions 8-15. Daily cone beam computed tomography (CBCT) was performed and registered to planning-CT using bony anatomy. Within-patient comparisons of mean daily chest wall position were made using a paired t-test. Population, systematic (∑) and random errors (α) were estimated. Intrafraction reproducibility was assessed by comparing chest wall position and diaphragm movement between consecutive breath holds on CBCT. RESULTS: 16 patients were recruited. All completed treatment with both techniques (9 patients with wax bolus, 7 patients without). CBCT derived ∑ were 2.1-6.4 mm (ABC_DIBH) and 2.1-4.9 mm (vDIBH), α were 1.7-2.6 mm (ABC_DIBH) and 2.2-2.7 mm (vDIBH) and mean daily chest wall displacements (MD) were 0.0-1.5 mm (ABC_DIBH) and -0.1-1.6 vDIBH (all p non-significant). Chest wall and diaphragm position was equivalent between consecutive breath holds in ABC and vDIBH (median difference 1.0 mm and 0.8 mm respectively, non p significant) demonstrating equivalent intrafraction reproducibility. CONCLUSION: This study demonstrates that a simple voluntary breath hold technique is feasible in combination with VMAT (+/- bolus) and is as reproducible as ABC_DIBH with VMAT for the irradiation of the breast and axillary and IMC lymph nodes in breast cancer patients.
ABSTRACT
PURPOSE/OBJECTIVE: Total body irradiation (TBI) remains a key component of conditioning for allogeneic haemopoietic stem cell transplant (HSCT), with interstitial pneumonitis (IP) and chronic kidney disease (CKD) important late sequelae. We undertook a retrospective service evaluation of TBI patients treated with a forward-planned intensity modulated radiotherapy technique (FP IMRT). MATERIAL/METHODS: 74 adult patients were identified; all received step and shoot FP IMRT TBI, 14.4 Gy in 8 fractions over 4 days. Mean doses to the lungs and kidneys were 12-12.5 Gy. Toxicities were defined as per CTCAE v4.0: IP as multilobar infiltrates on CT with symptoms of dyspnoea, and renal dysfunction as an Estimated Glomerular Filtration rate (eGFR) < 60 ml/min/1.73 m2 for > 3 months. Secondary endpoints were overall survival (OS), progression free survival (PFS), cumulative incidence of non-relapse mortality (NRM), relapse risk and of acute and chronic GvHD. RESULTS: Patients received treatment for the following diagnosis: ALL/LBL (n = 37); AML (n = 33), CML-BC (n = 2) and High grade NHL (n = 2). The rate of IP due to any cause was 30%; positive microbiological evidence in 73% (16 /22). Idiopathic IP was seen in 8%, with only 4% (n = 3) having IP Grade ≥ 3. Two (4%) of 52 long term survivors developed CKD, one with thrombotic microangiopathy. 4 year NRM was 16% (CI 11-32%); no treatment related deaths in matched sibling or umbilical cord blood HSCT. CONCLUSION: FP IMRT TBI, reducing dose to the lungs and kidneys, has lower rates of idiopathic IP and CKD compared to the literature. This technique is safe and effective conditioning for full intensity HSCT.
