Does the planning dose–volume histogram represent treatment doses in image-guided prostate radiation therapy? Assessment with cone-beam computerised tomography scans

Hatton, Joan; Greer, Peter B.; Tang, Colin; Wright, Philip; Capp, Anne; Gupta, Saurabh; Parker, J. Wm.; Wratten, Chris; Denham, James W.

doi:10.1016/j.radonc.2011.01.006

Cited by 67 publications

(69 citation statements)

References 36 publications

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“…In agreement with previous work, [22][23][24] greater variation in rectal dose distributions was seen, which for individual patients lead to a difference between planned and actual NTCP of sufficient magnitude to be of concern. Random variation in bowel distension means that delivered rectal doses can vary unpredictably, and hence the planned dose may be a poor predictor of actual rectal doses.…”

Section: Discussionsupporting

confidence: 91%

Image-guided radiotherapy of the prostate using daily CBCT: the feasibility and likely benefit of implementing a margin reduction

Maund¹,

Benson²,

Fairfoul³

et al. 2014

The British Journal of Radiology

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Objective: To investigate whether planning target volume (PTV) margins may be safely reduced in radiotherapy of localized prostate cancer incorporating daily online tube potential-cone beam CT (CBCT) image guidance and the anticipated benefit in predicted rectal toxicity. Methods: The prostate-only clinical target volume (CTV2) and rectum were delineated on 1 pre-treatment CBCT each week in 18 randomly selected patients. By transposing these contours onto the original plan, dose–volume histograms (DVHs) for CTV2 and the rectum were each calculated and combined, for each patient, to produce a single mean DVH representative of the dose delivered over the treatment course. Plans were reoptimized using reduced CTV2 to PTV2 margins and the consequent radiobiological impact modelled by the tumour control probability (TCP) and normal tissue complication probability (NTCP) of the rectum. Results: All CBCT images were deemed of sufficient quality to identify the CTV and rectum. No loss of TCP was observed when plans using the standard 5-mm CTV2 to PTV2 margin of the centre were reoptimized with a 4- or 3-mm margin. Margin reduction was associated with a significant decrease in rectal NTCP (5–4 mm; p < 0.05 and 5–3 mm; p < 0.01). Conclusion: Using daily online image guidance with CBCT, a reduction in CTV2 to PTV2 margins to 3 mm is achievable without compromising tumour control. The consequent sparing of surrounding normal tissues is associated with reduced anticipated rectal toxicity. Advances in knowledge: Margin reduction is feasible and potentially beneficial. Centres with image-guided radiotherapy capability should consider assessing whether margin reduction is possible within their institutes.

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Section: Discussionsupporting

confidence: 91%

Image-guided radiotherapy of the prostate using daily CBCT: the feasibility and likely benefit of implementing a margin reduction

Maund¹,

Benson²,

Fairfoul³

et al. 2014

The British Journal of Radiology

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“…McParland et al (6) in a study of five patients with prostate radiotherapy also observed that there was a significant difference in bladder and rectum volumes and doses as compared to the planning CT volumes and doses. Similarly, Hatton et al (7) also observed the difference in bladder and rectal volumes and doses in patients undergoing prostate radiotherapy. Landoni et al (8) have also studied the effect of setup errors and organ motion on prostate cancer IMRT and the results have proved that though rectum dose is very different than planned, it has negligible effect on prostate dose coverage.…”

Section: Introductionmentioning

confidence: 78%

Dosimetric and volumetric changes in the rectum and bladder in patients receiving CBCT‐guided prostate IMRT: analysis based on daily CBCT dose calculation

Pearson

Gill

Campbell

et al. 2016

J Applied Clin Med Phys

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Delivered dose can be calculated by transferring the planned treatment beams onto the daily CBCT. Bladder and rectum volumetric doses were calculated and correlated to the daily bladder and rectum fullness. Patients for this study underwent hypofractionated prostate IMRT to 70 Gy in 28 fractions. Daily CBCT was utilized for image guidance. A clinically acceptable plan was created using a CTV‐to‐PTV uniform margin of 5 mm. Image fusion was performed to transfer the bladder and rectum contours onto each CBCT. Contours were then edited to match the anatomy of each CBCT. Using the daily treatment isocenter, the planned beams were transferred onto the CBCT and daily and cumulative DVHs calculated. For the results a total of 168 daily CBCTs were evaluated. The bladder was found to be smaller for 74.7% of the 168 daily CBCTs accessed in this study. This reduction in volume correlated to an increase in the cumulative bladder V70 Gy from 9.47% on the planning CT to 10.99% during treatment. V70Gy for the rectum was 7.27% on the planning CT, when all six patients were averaged, and increased to 11.56% on the average of all daily treatment CBCTs. Increases in volumetric rectum dose correlated with increases in rectal volume. For one patient, the rectum and bladder absolute V70 Gy, averaged over the course of treatment, increased by 295% and 61%, respectively. Larger variations in the daily bladder and rectal volume were observed and these correlated to large deviations from the volumetric dose received by these structures. In summary, bladder and rectum volume changes during treatment have an effect on the cumulative dose received by these organs. It was observed that the volumetric dose received by the bladder decreases as the volume of the bladder increases. The inverse was true for the rectum.PACS number(s): 87.55.dk‐, 87.57.Q‐

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“…It is likely that patients were diagnosed with other comorbidities and prescribed with different types of medication at any time after that. It is also acknowledged that a DSH derived from a single treatment plan is only a surrogate parameter for the actual dose distribution received by the patient [41].…”

Section: Discussionmentioning

confidence: 99%

Dosimetry, clinical factors and medication intake influencing urinary symptoms after prostate radiotherapy: An analysis of data from the RADAR prostate radiotherapy trial

Yahya

Ebert

Bulsara

et al. 2015

Radiotherapy and Oncology

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Urinary symptoms (frequency, incontinence, dysuria and haematuria) were prospectively assessed using LENT-SOMA to a median of 72 months. The endpoints assessed were prevalence (grade≥1) at the end of radiotherapy (representing acute symptoms), at 18-, 36-and 54-month follow-ups (representing late symptoms) and peak late incidence including only grade≥2. Impact of factors were assessed using multivariate logistic regression models with correction for over-optimism. Results: Baseline symptoms, non-insulin dependent diabetes mellitus, age and PC1 (correlated to the mean dose) impact symptoms at >1 timepoints. Associations at a single timepoint were found for cerebrovascular condition, ECOG status and non-steroidal anti-inflammatory drug intake. Peak incidence analysis shows the impact of baseline, bowel and cerebrovascular condition and smoking status. Conclusions:The prevalence and incidence analysis provide a complementary view for urinary symptom prediction. Sustained impacts across time points were found for several factors while some associations were not repeated at different time points suggesting poorer or transient impact.4

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Does the planning dose–volume histogram represent treatment doses in image-guided prostate radiation therapy? Assessment with cone-beam computerised tomography scans

Cited by 67 publications

References 36 publications

Image-guided radiotherapy of the prostate using daily CBCT: the feasibility and likely benefit of implementing a margin reduction

Image-guided radiotherapy of the prostate using daily CBCT: the feasibility and likely benefit of implementing a margin reduction

Dosimetric and volumetric changes in the rectum and bladder in patients receiving CBCT‐guided prostate IMRT: analysis based on daily CBCT dose calculation

Dosimetry, clinical factors and medication intake influencing urinary symptoms after prostate radiotherapy: An analysis of data from the RADAR prostate radiotherapy trial

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