CyberKnife is the most advanced form of stereotactic body radiotherapy (SBRT) system that uses a robotic arm to deliver highly focused beams of radiation; however, a limitation is that it only irradiates from ceiling to floor direction. In patients with posterior lungs tumour who are positioned supine, normal lung tissue may suffer undesirable radiation injuries. This study compares the treatment planning between the prone set-up and the supine set-up for lung cancer in CyberKnife SBRT to decrease normal lung dose to avoid radiation side effects.

A human phantom was used to generate 108 plans (54 for prone and 54 for supine) using the CyberKnife planning platform. The supine and prone plans were compared in terms of the dosimetric characteristics, delivery efficiency and plan efficiency.

For posterior targets, the area of low-dose exposure to normal lungs was smaller in the prone set-up than in the supine set-up. V10 of the lungs was 7·53% and 10·47% (p < 0·001) in the anterior region, and 10·78% and 8·03% (p < 0·001) in the posterior region in the supine and prone set-up plans, respectively.

The comparison between the prone set-up and the supine set-up was investigated with regard to target coverage and dose to organs at risk. Our results may be deployed in CyberKnife treatment planning to monitor normal tissue dose by considering patient positioning. This may assist in the design of better treatment plans and prevention of symptomatic radiation pneumonitis in lung cancer patients.

Lung cancer is the most commonly diagnosed cancer in Canada and the leading cause of cancer-related mortality in both men and women in North America. Surgery is usually the primary treatment option for early-stage non-small cell lung cancer (NSCLC). However, for patients who may not be suitable candidates for surgery, stereotactic body radiation therapy (SBRT) is an alternative method of treatment. SBRT has proven to be an effective technique for treating NSCLC patients by focally administering high radiation dose to the tumour with acceptable risk of toxicity to surrounding healthy tissues. The goal of this comprehensive retrospective dosimetric study is to compare the dosimetric parameters between three-dimensional conformal radiation therapy (3DCRT) and volumetric-modulated arc therapy (VMAT) lung SBRT treatment plans for two prescription doses.

We retrospectively analysed and compared lung SBRT treatment plans of 263 patients treated with either a 3DCRT non-coplanar or with 2–3 VMAT arcs technique at 48 Gy in 4 fractions (48 Gy/4) or 50 Gy in 5 fractions (50 Gy/5) prescribed to the planning target volume (PTV), typically encompassing the 80% isodose volume. All patients were treated on either a Varian 21EX or TrueBeam linear accelerator using 6-MV or 10-MV photon beams.

The mean PTV V95% and V100% for treatment plans at 48 Gy/4 are 99·4 ± 0·6% and 96·0 ± 1·0%, respectively, for 3DCRT and 99·7 ± 0·4% and 96·4 ± 3·4%, respectively, for VMAT. The corresponding mean PTV V95% and V100% at 50 Gy/5 are 99·0 ± 1·4% and 95·5 ± 2·5% for 3DCRT and 99·5 ± 0·8% and 96·1 ± 1·6% for VMAT. The CIRI and HI5/95 for the PTV at 48 Gy/4 are 1·1 ± 0·1 and 1·2 ± 0·0 for 3DCRT and 1·0 ± 0·1 and 1·2 ± 0·0 for VMAT. The corresponding CIRI and HI5/95 at 50 Gy/5 are 1·1 ± 0·1 and 1·3 ± 0·1 for 3DCRT and 1·0 ± 0·1 and 1·2 ± 0·0 for VMAT. The mean R50% and D2cm at 48 Gy/4 are 5·0 ± 0·8 and 61·2 ± 7·0% for 3DCRT and 4·9 ± 0·8 and 57·8 ± 7·9% for VMAT. The corresponding R50% and D2cm at 50 Gy/5 are 4·7 ± 0·5 and 65·5 ± 9·4% for 3DCRT and 4·7 ± 0·7 and 60·0 ± 7·2% for VMAT.

The use of 3DCRT or VMAT technique for lung SBRT is an efficient and reliable method for achieving dose conformity, rapid dose fall-off and minimising doses to the organs at risk. The VMAT technique resulted in improved dose conformity, rapid dose fall-off from the PTV compared to 3DCRT, although the magnitude may not be clinically significant.

A systematic literature review was conducted to critically examine patient selection for patients undergoing stereotactic body radiotherapy (SBRT) to the spine and pancreas on the CyberKnife robotic radiosurgical system (CK). Online databases were searched and data was collected and ranked using a system from the Scottish Intercollegiate Guideline Network. The quality of the evidence analysed was insufficient to generate universal recommendations. However, the conclusions reached do help to demonstrate the safety and efficacy of CK treatment to both pancreatic and spinal patients.

Excellent local control rates and minimal acute toxicity were reported within the spinal literature with uncertainties remaining with regard to the precise tolerance of the spinal cord and the reliability of current toxicity prediction methods. For pancreatic patients prognosis remains dismal due to the tendency for patients to present with advanced or inoperable disease. Combinations of CK SBRT and Gemcitabine chemotherapy are given though regimes vary and overall survival is not extended due to the rapid onset of distant metastases. New chemotherapy agents are required as well as better means of predicting response to treatment.

No randomised controlled trials or meta-analyses were identified in the review and these are required in order to generate universal guidelines