Comparison of dose calculated by an intensity modulated radiotherapy treatment planning system and an independent monitor unit verification program.

A comparison of isocenter dose calculated by a commercial intensity modulated radiation therapy treatment planning system and independent monitor unit verification calculation (MUVC) software was made. The percent disparity between the treatment plan and MUVC doses were calculated for 507 treatments (head and neck, prostate, abdomen, female pelvis, rectum and anus, and miscellaneous) from 303 patients. The MUVC calculated dose was, on average, 1.4% higher than the treatment planning dose, with a 1.2% standard deviation. The distribution of the disparities appeared to be Gaussian in shape with some variation by treatment site. Based on our analysis, disparities outside the range of +/-3% about the mean value should be checked and resolved prior to treatment delivery.

Initial clinical experience with intensity-modulated whole-pelvis radiation therapy in women with gynecologic malignancies.

OBJECTIVE: Our goal in this article to describe our initial experience with intensity-modulated whole-pelvis radiation therapy (IM-WPRT) in gynecologic malignancies. METHODS: Between February and August 2000, 15 women with cervical (9) or endometrial (6) cancer received IM-WPRT. All patients received a treatment planning computed tomography (CT) scan. On each scan, the target volume (upper vagina, parametrial tissues, presacral region, uterus, and regional lymph nodes) and normal tissues (small bowel, bladder, and rectum) were identified. Using commercially available software, an IM-WPRT plan was generated for each patient. The goal was to provide coverage of the target with the prescription dose (45 Gy) while minimizing the volume of small bowel, bladder, and rectum irradiated. Acute gastrointestinal (GI) and genitourinary (GU) toxic effects in these women were compared with those seen in 25 patients treated with conventional WPRT. RESULTS: IM-WPRT plans provided excellent coverage of the target structures in all patients and were highly conformal, providing considerable sparing of the bladder, rectum, and small bowel. Treatment was well tolerated, with grade 0-1 GI and GU toxicity in 46 and 93% of patients, respectively. IM-WPRT patients had a lower rate of grade 2 GI toxicity (53.4% vs 96%, P = 0.001) than those treated with conventional WPRT. Moreover, the percentage of women requiring no or only infrequent antidiarrheal medications was lower in the IM-WPRT group (73.3% vs 20%, P = 0.001). While grade 2 GU toxicity was also lower in the IM-WPRT patients (6.7% vs 16%), this difference did not reach statistical significance (P = 0.38). CONCLUSION: IM-WPRT provides excellent coverage of the target structures while sparing critical neighboring structures in gynecology patients. Treatment is well tolerated with less acute GI toxicity than conventional WPRT. More patients and longer follow-up are needed to evaluate the full merits of this approach.

Quantization of setup uncertainties in 3-D dose calculations.

Random setup errors can lead to erroneous prediction of the dose distribution calculated for a patient using a static computed tomography (CT) model. Multiple recomputations of the dose distribution covering the range of expected patient positions provides a way to estimate a course of treatment. However, due to the statistical nature of the setup uncertainties, many courses of treatment must be simulated to calculate a distribution of average dose values delivered to a patient. Thus, direct simulation methods can be time consuming and may be impractical for routine clinical treatment planning applications. Methods have been proposed to efficiently calculate the distribution of average dose values via a convolution of the dose distribution (calculated on a static CT model) with a probability distribution function (generally Gaussian) that describes the nature of the uncertainty. In this paper, we extend the convolution-based calculation to calculate the standard deviation of potential outcomes sigmaD(x,y,z) about the distribution of average dose values, and we characterize the statistical significance of this quantity using the central limit theorem. For an example treatment plan based on a treatment protocol in use at our institution, we found that there is a 68% probability that the actual dose delivered to any point (x,y,z) will be within 3% of the average dose value at that point. The standard deviation also yields confidence limits on the dose distribution, and these may be used to evaluate treatment plan stability.

A method for incorporating organ motion due to breathing into 3D dose calculations.

A method is proposed that incorporates the effects of intratreatment organ motion due to breathing on the dose calculations for the treatment of liver disease. Our method is based on the convolution of a static dose distribution with a probability distribution function (PDF) which describes the nature of the motion. The organ motion due to breathing is assumed here to be one-dimensional (in the superior-inferior direction), and is modeled using a periodic but asymmetric function (more time spent at exhale versus inhale). The dose distribution calculated using convolution-based methods is compared to the static dose distribution using dose difference displays and the effective volume (Veff) of the uninvolved liver, as per a liver dose escalation protocol in use at our institution. The convolution-based calculation is also compared to direct simulations that model individual fractions of a treatment. Analysis shows that incorporation of the organ motion could lead to changes in the dose prescribed for a treatment based on the Veff of the uninvolved liver. Comparison of convolution-based calculations and direct simulation of various worst-case scenarios indicates that a single convolution-based calculation is sufficient to predict the dose distribution for the example treatment plan given.

Determination of rotations in three dimensions using two-dimensional portal image registration.

The relative relationships among anatomic features visualized on planar radiographic images change due to rotations of the patient out of the imaging plane. These changes can be predicted a priori from a three-dimensional radiographic model of the patient. In this study we assess the feasibility of using that information together with a planar image feature alignment tool to account for out-of-plane rotations in the evaluation of subsequent clinical patient images. A series of digitally reconstructed radiographs (DRRs) with known patient rotations was generated from a computed tomography scan of an anthropomorphic head phantom. Fixed anatomic features were extracted, as seen in the DRRs of rotated anatomy and entered into a database. Alignment of features from test radiographs with those from an entry in this database yielded an estimate of rotation out of plane (database entry that resulted in the best fit via planar transformation) along with the planar components of setup errors in the rotated plane. Tests using DRRs and films show that it is possible to select anatomic features in AP skull radiographs with position and orientation sensitive to out-of-plane rotation.

Duplicacion intestinal: informe de dos casos / Intestinal duplication: report of 2 cases

Las duplicaciones intestinales son infrecuentes y resultan de fallos embriológicos en la canalización normal del tubo digestivo. Este trabajo presenta un caso de duplicación intestinal en el ileon y su diagnóstico diferencial con el Divertículo de Meckel. A continuación se presenta un caso de duplicación de recto en un paciente de edad asintomático

Duplicacion intestinal: informe de dos casos / Intestinal duplication: report of 2 cases

Las duplicaciones intestinales son infrecuentes y resultan de fallos embriológicos en la canalización normal del tubo digestivo. Este trabajo presenta un caso de duplicación intestinal en el ileon y su diagnóstico diferencial con el Divertículo de Meckel. A continuación se presenta un caso de duplicación de recto en un paciente de edad asintomático (AU)

[Intestinal duplication. Report of 2 cases]. / Duplicación intestinal. Informe de dos casos.

Intestinal duplications are rare and they result from embryological failures in the canalization of the gastrointestinal tract. This paper presents a case of ileal intestinal duplication and its differential diagnosis from Meckel's diverticulum. Besides, a case of rectal duplication in an asymptomatic elder patient is presented.

Duplicación intestinal. Informe de dos casos. / [Intestinal duplication. Report of 2 cases]

Intestinal duplications are rare and they result from embryological failures in the canalization of the gastrointestinal tract. This paper presents a case of ileal intestinal duplication and its differential diagnosis from Meckels diverticulum. Besides, a case of rectal duplication in an asymptomatic elder patient is presented.

Duplicación intestinal. Informe de dos casos. / [Intestinal duplication. Report of 2 cases]

Intestinal duplications are rare and they result from embryological failures in the canalization of the gastrointestinal tract. This paper presents a case of ileal intestinal duplication and its differential diagnosis from Meckels diverticulum. Besides, a case of rectal duplication in an asymptomatic elder patient is presented.

[Incidence of intrahepatic and subcapsular hematomas after percutaneous needle biopsy]. / Incidencia de hematomas intrahepáticos y subcapsulares post punción biopsia percutánea del hígado.

Intrahepatic and subcapsular hematomas are described as complications of percutaneous liver biopsy. Even though, its incidence is not clearly established. Through this study we try to set which is the real incidence of this complication in our medium. To comply with this, we control our patients by ultrasonography before, after, and even seven days after procedure has been carried out.

Incidencia de hematomas intrahepáticos y subcapsulares post punción biopsia percutánea del hígado. / [Incidence of intrahepatic and subcapsular hematomas after percutaneous needle biopsy]

Intrahepatic and subcapsular hematomas are described as complications of percutaneous liver biopsy. Even though, its incidence is not clearly established. Through this study we try to set which is the real incidence of this complication in our medium. To comply with this, we control our patients by ultrasonography before, after, and even seven days after procedure has been carried out.