PURPOSE: To dosimetrically evaluate a margin-of-the-day (MoD) online adaptive intensity-modulated radiotherapy (IMRT) strategy for cervical cancer patients. The strategy is based on a single planning computed tomography (CT) scan and a pretreatment constructed IMRT plan library with incremental clinical target volumes (CTV)-to-planning target volumes (PTV) margins. MATERIAL AND METHODS: For 14 patients, 9-10 variable bladder filling CT scans acquired at pretreatment and after 40 Gy were available. Bladder volume variability during the treatment course was recorded by twice-weekly US bladder-volume measurements. A MoD strategy that selects the best IMRT plan of the day from a library of plans with incremental margins in steps of 5 mm was compared with a clinically recommended population-based margin (15 mm). To compare the strategies, for each fraction that had a recorded US bladder-volume measurement, the CT scan with the nearest bladder volume was selected from the pretreatment CT series and from the CT series acquired after 40 Gy. A frequency-weighted average of the dose-volume histograms (DVH) parameters calculated for the two selected CT scans was used to estimate the DVH parameters of the fraction of interest. RESULTS: The 15-mm recommended margin resulted in cervix-uterus underdosage in six of 14 patients. Compared with the 15-mm margin, the MoD strategy resulted in significantly better cervix-uterus coverage (p = 0.008) without a significant difference in the sparing of rectum, bladder, and small bowel. For each patient, 3-8 (median 5) plans were needed in the library of plans for the MoD strategy. The required range of the MoD was 5-45 mm (median 15 mm). Twenty-five percent of all fractions could be treated with a MoD of 5 mm and 81% of all fractions could be treated with a MoD up to 25 mm. CONCLUSIONS: Compared with a clinically recommended margin, a simple online adaptive strategy resulted in better cervix-uterus coverage without compromising organs at risk sparing.
PURPOSE: To dosimetrically evaluate a margin-of-the-day (MoD) online adaptive intensity-modulated radiotherapy (IMRT) strategy for cervical cancerpatients. The strategy is based on a single planning computed tomography (CT) scan and a pretreatment constructed IMRT plan library with incremental clinical target volumes (CTV)-to-planning target volumes (PTV) margins. MATERIAL AND METHODS: For 14 patients, 9-10 variable bladder filling CT scans acquired at pretreatment and after 40 Gy were available. Bladder volume variability during the treatment course was recorded by twice-weekly US bladder-volume measurements. A MoD strategy that selects the best IMRT plan of the day from a library of plans with incremental margins in steps of 5 mm was compared with a clinically recommended population-based margin (15 mm). To compare the strategies, for each fraction that had a recorded US bladder-volume measurement, the CT scan with the nearest bladder volume was selected from the pretreatment CT series and from the CT series acquired after 40 Gy. A frequency-weighted average of the dose-volume histograms (DVH) parameters calculated for the two selected CT scans was used to estimate the DVH parameters of the fraction of interest. RESULTS: The 15-mm recommended margin resulted in cervix-uterus underdosage in six of 14 patients. Compared with the 15-mm margin, the MoD strategy resulted in significantly better cervix-uterus coverage (p = 0.008) without a significant difference in the sparing of rectum, bladder, and small bowel. For each patient, 3-8 (median 5) plans were needed in the library of plans for the MoD strategy. The required range of the MoD was 5-45 mm (median 15 mm). Twenty-five percent of all fractions could be treated with a MoD of 5 mm and 81% of all fractions could be treated with a MoD up to 25 mm. CONCLUSIONS: Compared with a clinically recommended margin, a simple online adaptive strategy resulted in better cervix-uterus coverage without compromising organs at risk sparing.
Authors: Nina Boje Kibsgaard Jensen; Marianne Sanggaard Assenholt; Lars Ulrik Fokdal; Anne Vestergaard; Annette Schouboe; Eva Bruun Kjaersgaard; Annette Boejen; Lars Nyvang; Jacob Christian Lindegaard; Kari Tanderup Journal: Phys Imaging Radiat Oncol Date: 2018-12-20
Authors: Hannes A Loebner; Werner Volken; Silvan Mueller; Jenny Bertholet; Paul-Henry Mackeprang; Gian Guyer; Daniel M Aebersold; Marco F M Stampanoni; Peter Manser; Michael K Fix Journal: Med Phys Date: 2022-05-04 Impact factor: 4.506
Authors: Peter de Boer; Agustinus J A J van de Schoot; Henrike Westerveld; Mark Smit; Marrije R Buist; Arjan Bel; Coen R N Rasch; Lukas J A Stalpers Journal: Strahlenther Onkol Date: 2017-11-03 Impact factor: 3.621