Clinical variability of target volume description in conformal radiotherapy planning

SummaryTo compare the image quality of cone beam CT (CBCT) with that of planning CT (pCT) scan, and quantify inter-observer differences in therapeutic indices based on these scans prior to the introduction of an adaptive radiation therapy protocol for bladder cancer. Four consecutive patients were selected with muscle invasive bladder cancer receiving radical dose radiation therapy. Four radiation oncologists specializing in genitourinary malignancies contoured the clinical target volume (CTV) and rectum on both a pCT and a randomly chosen CBCT of the same patient. A conformity index (CI) for CTV and the rectum was determined for both pCT and CBCT. The maximal lateral, anterior, posterior, cranial and caudal extensions of the CTV for both CT and CBCT were determined for each observer. Variation in volumes of both the CTV and rectum for both pCT and were also compared using Varian Eclipse planning software (Varian Medical Systems, Palo Alto, CA, USA). Using pCT the mean CI for the CTV was 0.79; using CBCT the mean CI for the CTV was 0.75. For the rectum, the mean CI for using CT was 0.80 and for CBCT was 0.74. Greatest variation on CBCT CTV contours was seen in the supero-inferior direction with variation up to 2.1 cm between different radiation oncologists. With the variation in CI for pCT and CBCT of the CTV and rectum (0.04 and 0.06 respectively), CBCT is not significantly inferior to the pCT in terms of inter-observer contouring variability.

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“…10 As whole bladder coverage is our current practice, this inter-observer study was based on contouring the whole organ.…”

Section: 13-15mentioning

confidence: 99%

Inter‐observer variability of clinical target volume delineation for bladder cancer using CT and cone beam CT

et al. 2009

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“…3 H]water and [ 14 C]urea permeabilities were measured with a specially designed Ussing chamber as previously described (22,23,26,32,42).…”

Section: Nested Rt-pcr For Detection Of Human Mnsod Transgene Expressmentioning

confidence: 99%

Manganese superoxide dismutase gene therapy protects against irradiation-induced cystitis

Kanai¹,

Zeidel²,

Lavelle³

et al. 2002

American Journal of Physiology-Renal Physiology

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Urinary bladder cystitis occurs in patients receiving radiation therapy for pelvic tumors. Radiation-induced formation of superoxide radicals is believed to damage the urothelium, exposing the underlying bladder smooth muscle to urine, culminating in nerve irritation and muscle dysfunction. We tested whether overexpression of MnSOD could decrease superoxide levels and protect the bladder from radiation damage. Pelvic irradiation led to sloughing of urothelial umbrella cells, with decreased transepithelial resistance, increased water and urea permeabilities, and increased expression of inducible nitric oxide synthase. Six months after irradiation, cystometrograms showed elevated intravesical pressures and prolonged voiding patterns. However, urothelia transfected with the MnSOD transgene recovered from radiation injury more rapidly, and detrusor function was much closer to that of control bladders than irradiated bladders without the transgene. We conclude that MnSOD gene therapy is protective, which could lead to its use in mitigating radiation cystitis and preventing dysfunction of the urinary bladder.

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“…Even when visible, postoperative stranding, borders between the lumpectomy site and chest wall or skin, and dense breast parenchyma can obscure the borders of the lumpectomy cavity. In addition to the challenges in identification of the lumpectomy site, several studies have shown interobserver differences in contouring radiation target volumes [5][6][7]. Rates of discordance in interobserver studies have conformity indices approaching 50% [2,8].…”

Section: Discussionmentioning

confidence: 99%

Image-based Treatment Planning of the Post-lumpectomy Breast Utilizing CT and 3T MRI

Buechler-Price¹,

Betts²,

Muruganandham³

et al. 2009

International Journal of Radiation Oncology*Biology*Physics

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Accurate lumpectomy cavity definition is critical in breast treatment planning. We compared contouring lumpectomy cavity volume and cavity visualization score (CVS) with CT versus 3T MRI. 29 patients were imaged with CT and 3T MRI. Seven additional boost planning sets were obtained for 36 image sets total. Three observers contoured the lumpectomy cavity on all images, assigning a cavity visualization score (CVS ) of 1 to 5. Measures of consistency and agreement for CT volumes were 98.84% and 98.62%, for T1 MRI were 95.65% and 95.55%, and for T2 MRI were 97.63% and 97.71%. The mean CT, T1 MRI, and T2 MRI CVS scores were 3.28, 3.38, and 4.32, respectively. There was a highly significant difference between CT and T2 scores (P < .00001) and between T1 and T2 scores (P < .00001). Interobserver consistency and agreement regarding volumes were high for all three modalities with T2 MRI CVS the highest. MRI may contribute to target definition in selected patients.

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Clinical variability of target volume description in conformal radiotherapy planning

Cited by 126 publications

References 9 publications

Inter‐observer variability of clinical target volume delineation for bladder cancer using CT and cone beam CT

Inter‐observer variability of clinical target volume delineation for bladder cancer using CT and cone beam CT

Manganese superoxide dismutase gene therapy protects against irradiation-induced cystitis

Image-based Treatment Planning of the Post-lumpectomy Breast Utilizing CT and 3T MRI

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