Shortening the preparation time of the single prolonged breath-hold for radiotherapy sessions.

OBJECTIVE: Single prolonged breath-holds of >5 min can be obtained in cancer patients. Currently, however, the preparation time in each radiotherapy session is a practical limitation for clinical adoption of this new technique. Here, we show by how much our original preparation time can be shortened without unduly compromising breath-hold duration. METHODS: 44 healthy subjects performed single prolonged breath-holds from 60% O2 and mechanically induced hypocapnia. We tested the effect on breath-hold duration of shortening preparation time (the durations of acclimatization, hyperventilation and hypocapnia) by changing these durations and or ventilator settings. RESULTS: Mean original breath-hold duration was 6.5 ± 0.2 (standard error) min. The total original preparation time (from connecting the facemask to the start of the breath-hold) was 26 ± 1 min. After shortening the hypocapnia duration from 16 to 5 min, mean breath-hold duration was still 6.1 ± 0.2 min (ns vs the original). After abolishing the acclimatization and shortening the hypocapnia to 1 min (a total preparation time now of 9 ± 1 min), a mean breath-hold duration of >5 min was still possible (now significantly shortened to 5.2 ± 0.6 min, p < 0.001). After shorter and more vigorous hyperventilation (lasting 2.7 ± 0.3 min) and shorter hypocapnia (lasting 43 ± 4 s), a mean breath-hold duration of >5 min (5.3 ± 0.2 min, p < 0.05) was still possible. Here, the final total preparation time was 3.5 ± 0.3 min. CONCLUSIONS: These improvements may facilitate adoption of the single prolonged breath-hold for a range of thoracic and abdominal radiotherapies especially involving hypofractionation. ADVANCES IN KNOWLEDGE: Multiple short breath-holds improve radiotherapy for thoracic and abdominal cancers. Further improvement may occur by adopting the single prolonged breath-hold of >5 min. One limitation to clinical adoption is its long preparation time. We show here how to reduce the mean preparation time from 26 to 3.5 min without compromising breath-hold duration.

The feasibility, safety and optimization of multiple prolonged breath-holds for radiotherapy.

BACKGROUND & PURPOSE: Multiple, short breath-holds are now used in single radiotherapy treatment sessions. Here we investigated the feasibility and safety of multiple prolonged breath-holds in a single session. We measured how long is a second breath-hold if we prematurely terminate a single, prolonged breath-hold of >5 min either by using a single breath of oxygen (O2), or by reintroducing preoxygenation and hypocapnia. We also investigated the feasibility and safety of undertaking 9 prolonged breath-holds in a row. MATERIALS & METHODS: 30 healthy volunteers with no previous breath-holding experience were trained to perform single prolonged breath-holds safely. RESULTS: Their mean single, prolonged breath-hold duration was 6.1 ±â€¯0.3 se minutes (n = 30). In 18/18 subjects, premature termination (at 5.1 ±â€¯0.2 min) with a single breath of 60% O2, enabled a 2nd safe breath-hold lasting 3.3 ±â€¯0.2 min. In 18/18 subjects, premature termination at 5.3 ±â€¯0.2 min) by reintroducing preoxygenation and hypocapnia, enabled a 2nd safe breath-hold lasting 5.8 ±â€¯0.3 min. 17/17 subjects could safely perform 9 successive prolonged breath-holds, each terminated (at 4.3 ±â€¯0.2 min) by reintroducing preoxygenation and hypocapnia for 3.1 ±â€¯0.2 min. The 9th unconstrained breath-hold (mean of 6.0 ±â€¯0.3 min) lasted as long as their single breath-hold. CONCLUSIONS: Multiple prolonged breath-holds are possible and safe. In a ∼19 min treatment session, it would therefore be possible to have ∼13 min for radiotherapy treatment (3 breath-holds) and ∼6 min for setup and recovery. In a 65 min session, it would be possible to have 41 min for radiotherapy and 25 min for setup and recovery.