title: Treatment planning and evaluation of gated radiotherapy in left-sided breast cancer patients using the CatalystTM/SentinelTMsystem for deep inspiration breath-hold (DIBH).
abstract: BACKGROUND
  There is a potential for adverse cardiovascular effects in long-term breast cancer survivors following adjuvant radiotherapy (RT). For this purpose, the deep inspiration breath-hold technique (DIBH) has been introduced into clinical practice, to maximally reduce the radiation dose to the heart. However, there are a variety of DIBH delivery techniques, patient positioning and visual patient feedback mechanisms. The aim of the present study was to evaluate the application of radiotherapy in DIBH using the CatalystTM/SentinelTMsystem, with a special emphasis on treatment planning and dosimetric plan comparison in free breathing (FB) and DIBH.
  
  
  METHODS
  A total of 13 patients with left-sided breast cancer following breast conserving surgery were included in this prospective clinical trial. For treatment application the CatalystTM/SentinelTMsystem (C-RAD AB, Uppsala, Sweden) was used and gating control was performed by an audio-visual patient feedback system. CT and surface data were acquired in FB and DIBH and dual treatment plans were created using Pencil Beam and Collapsed Cone Convolution. Dosimetric output parameters of organs at risk were compared using Wilcoxon signed-rank test. Central lung distance (CLD) was retrieved from iViewTMportal images during treatment delivery.
  
  
  RESULTS
  The system contains a laser surface scanner (SentinelTM) and an optical surface scanner (CatalystTM) interconnected to the LINAC systems via a gating interface and allows for a continuous and touchless surface scanning. Overall, 225 treatment fractions with audio-visual guidance were completed without any substantial difficulties. Following initial patient training and treatment setup, radiotherapy in DIBH with the CatalystTM/SentinelTMsystem was time-efficient and reliable. Following dual treatment planning for all patients, nine of 13 patients were treated in DIBH. In these patients, the reduction of the mean heart dose for DIBH compared to FB was 52 % (2.73 to 1.31 Gy; p = 0.011). The maximum doses to the heart and LAD were reduced by 59 % (47.90 to 19.74 Gy; p = 0.008) and 75 % (38.55 to 9.66 Gy; p = 0.008), respectively. In six of the nine patients the heart completely moved out of the treatment field by DIBH. The standard deviation of the CLD varied between 0.12 and 0.29 cm (mean: 0.16 cm).
  
  
  CONCLUSIONS
  The CatalystTM/SentinelTMsystem enabled a fast and reliable application and surveillance of DIBH in daily clinical routine. Furthermore, the present data show that using the DIBH technique during RT could significantly reduce high dose areas and mean doses to the heart.
  
  
  BACKGROUND
  DRKS: DRKS00010929 registered on 5. August 2016.
authors: Department of Radiation Oncology, LMU University, Marchioninistraße 15, 81377, Munich, Germany.
authors: S
authors: S
authors: Schönecker
authors: Department of Radiation Oncology, LMU University, Marchioninistraße 15, 81377, Munich, Germany.
authors: F
authors: F
authors: Walter
authors: Department of Radiation Oncology, LMU University, Marchioninistraße 15, 81377, Munich, Germany.
authors: P
authors: P
authors: Freislederer
authors: Medical Clinic and Policlinic I, LMU University, Munich, Germany.
authors: C
authors: C
authors: Marisch
authors: Department of Radiation Oncology, LMU University, Marchioninistraße 15, 81377, Munich, Germany.
authors: H
authors: H
authors: Scheithauer
authors: Breast Center, Department of Obstetrics and Gynecology, LMU University, Munich, Germany.
authors: N
authors: N
authors: Harbeck
authors: Department of Radiation Oncology, LMU University, Marchioninistraße 15, 81377, Munich, Germany. Stefanie.Corradini@med.uni-muenchen.de.
authors: S
authors: S
authors: Corradini
authors: Department of Radiation Oncology, LMU University, Marchioninistraße 15, 81377, Munich, Germany.
authors: C
authors: C
authors: Belka
mesh_terms: D000328:Adult; D062485:Breath Holding; D005260:Female; D006801:Humans; D015412:Mastectomy, Segmental; D008875:Middle Aged; D011446:Prospective Studies; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D014057:Tomography, X-Ray Computed; D000069584:Unilateral Breast Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*
keywords: Audio-visual guided; Breast cancer; Cardiac toxicity; CatalystTM; Deep inspiration breath-hold (DIBH); Left-sided; Surface scanner