Dosimetric assessment of prostate cancer patients through principal component analysis (PCA)

Abstract

The aims of this study were twofold: first, to determine the impact of variance in dose‐volume histograms (DVH) on patient‐specific toxicity after 2 high‐dose fractions in a sample of 22 men with prostate cancer; and second, to compare the effectiveness of traditional DVH analysis and principal component analysis (PCA) in predicting rectum and urethra toxicity. A series of 22 patients diagnosed with prostate adenocarcinoma was treated with 45 Gy external beam and 20 Gy dose rate brachytherapy. Principal component analysis was applied to model the shapes of the rectum and urethra dose‐volume histograms. We used logistic regression to measure the correlations between the principal components and the incidence of rectal bleeding and urethra stricture. We also calculated the equivalent uniform dose (EUD) and normal tissue complication probability (NTCP) for the urethra and rectum, and tumor control probability (TCP) for the prostate using BioSuite software. We evaluated their correlations with rectal and urethra toxicity. The rectum DVHs are well described by one principal component (PC1), which accounts for 93.5% of the variance in their shapes. The urethra DVHs are described by two principal components, PC1 and PC2, which account for 94.98% and 3.15% of the variance, respectively. Multivariate exact logistic regression suggests that urethra PC2 is a good predictor of stricture, with Nagelkerke's R2 estimated at 0.798 and a Wald criterion of 5.421 (normalp<0.021). The average NTCPs were 0.06%±0.04% and 1.25%±0.22% for the rectum and urethra, respectively. The average TCP was 85.29%±2.28%. This study suggests that principal component analysis can be used to identify the shape variation in dose‐volume histograms, and that the principal components can be correlated with the toxicity of a treatment plan based on multivariate analysis. The principal components are also correlated with traditional dosimetric parameters.PACS number: 3.6.96.0

Multiparametric MRI-guided dose boost to dominant intraprostatic lesions in CT-based High-dose-rate prostate brachytherapy

“…43 Another publication also provides a set of NTCP LKB parameters of urethra without additional sources. 50 To the best of our knowledge, these are the only two publications presenting urethra NTCP LKB modeling parameters. Another important caveat is that given our assumption of urethral dose in the EBRT combination cohort, the reliability of the NTCP calculation may be affected and therefore should be viewed with caution.…”

Predicting toxicity caused by high-dose-rate brachytherapy single boost for prostate cancer

“…To facilitate physicians in predicting toxicity risks and therefore in planning, the most favorable treatment for PC patients with predictive models that estimate the probability of a certain toxicity outcome have been developed [11][12][13][14][15]. Interestingly, most of these models predict outcomes of interest following EBRT, and scarcely any predicting toxicity after treatment with combined HDR-BT and EBRT can be found [16,17].…”

Stereotactic Radiotherapy after Radical Prostatectomy in Patients with Prostate Cancer in the Adjuvant or Salvage Setting: A Systematic Review

“…The rationale for using SBRT in patients with prostate cancer is the low α/β value of about 1.5 Gy [27,28]. The organs at risk in close proximity to the prostate like the bladder, rectum or urethra for instance have a higher α/β value of 3-6 [29][30][31][32]. Therefore, using a larger fraction dose is expected to improve the therapeutic ratio and consequently the probability of tumor control.…”