Radiation Dose Rate, Biologically Effective Dose, and Tumor Characteristics on Local Control and Toxicity After Radiosurgery for Acoustic Neuromas.

OBJECTIVE: To evaluate the relationships between calibration dose rate, calculated biologically effective dose (BED), and clinical factors and tumor control after stereotactic radiosurgery (SRS) for acoustic neuroma. METHODS: We performed a retrospective study of all patients with acoustic neuromas treated with frame-based cobalt-60 SRS at a single institution between 2005 and 2019. The calibration dose rate and cobalt-60 half-life were used to calculate the nominal dose rate during treatment. An SRS-specific monoexponential model accounting for treatment time per lesion was used to estimate BED. RESULTS: The study included 607 patients with 612 acoustic neuromas. Median follow-up was 5.0 years. There was no association between dose rate or BED with local failure (LF), radiologic edema, or symptomatic edema. Cystic tumors (adjusted hazard ratio 0.26, P = 0.028) were associated with lower LF, while use of SRS as salvage treatment for growing tumors (adjusted hazard ratio 4.9, P < 0.0001) was associated with higher LF. LF occurred more frequently in larger-diameter tumors, while radiologic or symptomatic edema occurred more frequently in larger-volume tumors. CONCLUSIONS: Radiosurgery dose rate and BED were not associated with tumor control or radiologic or symptomatic edema. Salvage SRS and larger tumors were associated with a higher LF rate, while cystic tumors were associated with a lower LF rate. Patients with larger tumors should be counseled appropriately about potential side effects and when to seek follow-up care.

Evaluation of Long-Term Outcomes and Toxicity After Stereotactic Phosphorus-32-Based Intracavitary Brachytherapy in Patients With Cystic Craniopharyngioma.

PURPOSE: Interstitial brachytherapy based on phosphorus-32 (P-32) has an established role as a minimally invasive treatment modality for patients with cystic craniopharyngioma. However, reporting on long-term outcomes with toxicity profiles for large cohorts is lacking in the literature. The purpose of this study is therefore to evaluate the long-term visual, endocrinal, and neurocognitive functions in what is the largest patient series having received this treatment to date. METHODS AND MATERIALS: We retrospectively evaluated 90 patients with cystic craniopharyngiomas who were treated with stereotactic intracavitary brachytherapy between 1998 and 2010. Colloidal activity of injected radioisotope P-32 was based on an even distribution within the tumor. After treatment, patients were followed-up for a minimum of 5 years and over a mean of 121 months (60-192 months) to assess radiographic and clinical responses. RESULTS: The 90 patients included in our study cohort underwent a total of 108 stereotactic surgical procedures for 129 craniopharyngioma-related cysts. Of the included tumors, 65 (72.2%) were associated with a single cyst, 15 (16.7%) were associated with 2 cysts, and 10 (11.1%) tumors had developed septations with 3 to 4 cysts. Stereotactic cyst puncture and content aspiration were used to drain a mean cyst fluid volume of 21.4 mL (1.0-55.0 mL). Each cyst was then instilled for interstitial brachytherapy with colloidal P-32 solution. Based on radiographic follow-up assessments, 56 cysts (43.4%) showed resolution and/or nonrecurrence, which was classified as a complete response to treatment; 47 cysts (36.4%) showed a partial response; and 5 cysts (3.9%) displayed a stable appearance. Treatment resulted in immediate and clinically significant vision improvement in 54 of 63 (86%) symptomatic patients, and this improvement was maintained. Progression-free survival rates at 5 and 10 years were 95.5% and 84.4%, respectively. CONCLUSIONS: P-32-based interstitial brachytherapy can play an effective role in managing patients with cystic craniopharyngiomas. It can be considered a valid alternative to surgery in select patients with a favorable toxicity profile and long-term clinical outcomes.

Meta-analysis of tumor control rates in patients undergoing stereotactic radiosurgery for cystic vestibular schwannomas.

OBJECTIVE: The use of SRS for treatment of cystic vestibular schwannoma is a topic of mild controversy. This review serves to introduce a renewed understanding of the efficacy of SRS as a viable treatment modality for cystic VS. PATIENTS AND METHODS: This study was conducted in accordance with the PRISMA guidelines. A broad search of the literature was conducted in October 2018 through the PubMed, Scopus, Embase, Web of Science, and Cochrane databases. Meta-analysis was conducted on tumor control rates and heterogeneity between articles was assessed using τ2, Cochran's Q, and I2 statistics. RESULTS: A total of 246 patients underwent SRS for cystic VS, with reported mean or median follow-up ranging from 49.7 to 150 months, and an overall range of 6-201 months. Following SRS treatment for cystic VS across all studies, 92% of patients had tumor control at follow up, (95%-CI: 88-95%). Tumor control rate specifically for patients who underwent GammaKnife was 93% (95-CI: 88%-95%). CONCLUSION: Despite the paucity of pertinent data, the results of our meta-analysis suggest that SRS exhibits effective tumor control rates in patients with cystic VS. Therefore, SRS can be considered a viable treatment modality when choosing amongst interventions for cystic VS.

Local control after brain-directed radiation in patients with cystic versus solid brain metastases.

PURPOSE: Brain metastases can be radiographically cystic or solid. Cystic metastases are associated with a greater intracranial disease burden and poorer oncologic outcomes, but the impact of cystic versus solid appearance on local control after radiation remains unknown. We investigated whether cystic versus solid nature is predictive of local control after management with stereotactic or whole brain radiation (WBRT) and whether the radiation modality utilized is an effect modifier. METHODS: We identified 859 patients with 2211 newly-diagnosed brain metastases managed with upfront stereotactic radiation or WBRT without preceding resection/aspiration at Brigham and Women's Hospital/Dana-Farber Cancer Institute between 2000 and 2015. Multivariable Cox regression with an interaction term and sandwich covariance matrix was used to quantify local failure. RESULTS: Cystic lesions were more likely to recur than solid ones when managed with stereotactic radiation (HR 2.33, 95% CI 1.32-4.10, p = 0.004) but not WBRT (HR 0.92, 95% CI 0.62-1.36, p = 0.67), p-interaction = 0.007. 1 year local control rates for cystic versus solid metastases treated with stereotactic radiation were 75% versus 88%, respectively; estimates with WBRT were 76% versus 76%, respectively. However, no significant differences were noted between the two cohorts in post-radiation outcomes including all-cause mortality and neurologic death (p > 0.05). CONCLUSIONS: Among patients with brain metastases, stereotactic radiation yields improved local control and less morbidity than WBRT, and consequently for many patients the cystic versus solid designation does not impact treatment selection. However, our results suggest that in patients with a large number of cystic brain metastases, a lower threshold to consider WBRT, as opposed to stereotactic radiation, should be employed. If our results can be confirmed, further investigation into the underlying mechanism(s) would be warranted.

Evaluation of Bremsstrahlung radiation dose in stereotactically radiocolloid therapy of cystic craniopharyngioma tumors with 32P radio-colloid.

Over 90% of craniopharyngeal brain tumors are cystic, which enables the injection of beta emitters such as phosphorus-32 (32P) radio-colloid into cysts for their treatment. The aim of this study was to evaluate the clinical and theoretical modelling of Bremsstrahlung radiation dose resulting from stereotactic radio-colloid therapy of cystic craniopharyngioma tumors with 32P. 32P radio-colloid with appropriate activity concentration was injected to a head phantom, and then the Bremsstrahlung radiation spectrum and planar images were obtained using a gamma camera. Both phantom and gamma camera were simulated using MCNPX code, and the results were compared with practical results. Bremsstrahlung radiation spectrum was measured using a handheld gamma spectrometer for two patients treated with stereotactic radio-colloid therapy with 32P in different positions and compared to Monte Carlo simulation. Results of counting and determining sensitivity coefficients in the air and the attenuating environment were obtained. Also, comparing the counting sensitivity from practical and simulation methods indicated the agreement of the data between the two methods. Comparison of the spectra from different positions around patient's head indicated the ability to use this detector to quantify the activity in the operating room. Selection of the spectrum is important in Bremsstrahlung radiation imaging. We can take advantage of spectrometry measurement using gamma camera, handheld gamma spectrometer for patient, and theoretical modeling with Monte Carlo code to evaluate radiopharmaceutical distribution, leakage, as well as estimate activity and predict therapeutic effects in other adjacent structures and ultimately optimize radio-colloid therapy in cystic craniopharyngeal patients.

[Transient enlargement of craniopharyngioma cysts after stereotactic radiotherapy and radiosurgery]. / Tranzitornoe uvelichenie ob''ema kist kraniofaringiom posle stereotaksicheskoi luchevoi terapii i radiokhirurgii.

Stereotactic radiotherapy/radiosurgery (RT/ES) is an effective technique for treating craniopharyngiomas (CPs). However, enlargement of the cystic part of the tumor occurs in some cases after irradiation. The enlargement may be transient and not require treatment or be a true relapse requiring treatment. MATERIAL AND METHODS: In this study, we performed a retrospective analysis of 79 pediatric patients who underwent stereotactic RT or RS after resection of craniopharyngioma. RESULTS: Five-year relapse-free survival after complex treatment of CP was 86%. In the early period after irradiation, 3.5 months (2.7-9.4) on average, enlargement of the cystic component of the tumor was detected in 10 (12.7%) patients; in 9 (11.4%) of them, the enlargement was transient and did not require treatment; in one case, the patient underwent surgery due to reduced visual acuity. In 8 (10.1%) patients, an increase in the residual tumor (a solid component of the tumor in 2 cases and a cystic component of the tumor in 6 cases) occurred in the long-term period after irradiation - after 26.3 months (16.6-48.9) and did not decrease during follow-up in none of the cases, i.e. continued growth of the tumor was diagnosed. A statistical analysis revealed that differences in the terms of transient enlargement and true continued growth were statistically significant (p<0.01). CONCLUSION: Enlargement of a craniopharyngioma cyst in the early period (up to 1 year) after RT/RS is usually transient and does not require surgical treatment (except cases where worsening of neurological symptoms occurs, or occlusive hydrocephalus develops).

Patient-specific dosimetry for intracavitary 32P-chromic phosphate colloid therapy of cystic brain tumours.

PURPOSE: (32)P-chromic phosphate colloid treatments of astrocytoma and craniopharyngioma cystic brain tumours in paediatric patients are conventionally based on a sphere model under the assumption of uniform uptake. The aims of this study were to determine the distribution of the absorbed dose delivered by (32)P on a patient-specific basis and to evaluate the accuracy with which this can be predicted from a pretherapy administration of (99m)Tc-Sn colloid. METHODS: Three patients were treated with (32)P-chromic phosphate colloid following (99m)Tc-Sn colloid administrations. Convolution dosimetry was performed using pretherapy and posttherapy sequential SPECT imaging, and verified with EGSnrc Monte Carlo radiation transport simulations. Mean absorbed doses to the cyst wall and dose-volume histograms were also calculated and compared with those obtained by the sphere model approach. RESULTS: Highly nonuniform uptake distributions of both the (99m)Tc and (32)P colloids were observed and characterized by dose-volume histograms to the cyst wall. Mean absorbed doses delivered to the cyst wall, obtained with the convolution method, were on average 21 % (SD 18 %) and 50 % (SD 30 %) lower than those predicted by the (99m)Tc distribution and the uniform assumption of the sphere model, respectively. CONCLUSION: Absorbed doses delivered to the cyst wall by (32)P are more accurately predicted from image-based patient-specific convolution dosimetry than from simple sphere models. These results indicate the necessity to perform personalized treatment planning and verification for intracavitary irradiation of cystic brain tumours treated with radiocolloids. Patient-specific dosimetry can be used to guide the frequency and levels of repeated administrations and would facilitate data collection and comparison to support the multicentre trials necessary to progress this therapy.

Treatment of cystic craniopharyngioma with 90Y-Colloid. Four clinical cases.

Craniopharyngioma is a histologically benign and frequently cystic intracranial tumor. It may present aggressive behavior due to compression from nearby structures. Its therapeutic management is complicated because although surgery is the usual treatment of choice, it is not exempt of high morbidity and mortality and frequent tumor recurrence. In craniopharyngiomas with a significant cystic component,internal irradiation with radioactive isotopes is a therapeutic alternative to conventional treatments. We present the cases of four patients with cystic craniopharyngiomas who were treated with intracystic administration of 90Y-colloid, and their evolution after the treatment.

Gamma knife radiosurgery for the treatment of cystic cerebral metastases.

PURPOSE: To assess the role of Gamma Knife radiosurgery (GKRS) in the treatment of nonsurgical cystic brain metastasis, and to determine predictors of response to GKRS. METHODS: We reviewed a prospectively maintained database of brain metastases patients treated at our institution between 2006 and 2010. All lesions with a cystic component were identified, and volumetric analysis was done to measure percentage of cystic volume on day of treatment and consecutive follow-up MRI scans. Clinical, radiologic, and dosimetry parameters were reviewed to establish the overall response of cystic metastases to GKRS as well as identify potential predictive factors of response. RESULTS: A total of 111 lesions in 73 patients were analyzed; 57% of lesions received prior whole-brain radiation therapy (WBRT). Lung carcinoma was the primary cancer in 51% of patients, 10% breast, 10% colorectal, 4% melanoma, and 26% other. Fifty-seven percent of the patients were recursive partitioning analysis class 1, the remainder class 2. Mean target volume was 3.3 mL (range, 0.1-23 mL). Median prescription dose was 21 Gy (range, 15-24 Gy). Local control rates were 91%, 63%, and 37% at 6, 12, and 18 months, respectively. Local control was improved in lung primary and worse in patients with prior WBRT (univariate). Only lung primary predicted local control in multivariate analysis, whereas age and tumor volume did not. Lesions with a large cystic component did not show a poorer response compared with those with a small cystic component. CONCLUSIONS: This study supports the use of GKRS in the management of nonsurgical cystic metastases, despite a traditionally perceived poorer response. Our local control rates are comparable to a matched cohort of noncystic brain metastases, and therefore the presence of a large cystic component should not deter the use of GKRS. Predictors of response included tumor subtype. Prior WBRT decreased effectiveness of SRS for local control rates.

Manejo multidisciplinar del cáncer epitelial de ovario. Diagnóstico radiológico / Multidisciplinary management of ovarian epithelial cancer. Radiological diagnosis

En el contexto del abordaje multidisciplinar parael diagnóstico y tratamiento del cáncer de ovario, laaportación del radiólogo incluye cuatro puntos fundamentalesque son: identificación de la lesión, caracterización,estudio de extensión y valoración evolutiva.En el presente trabajo se describen los hallazgos y clavesdiagnósticas en TCMD (Tomografía Computarizadamultidetector) y RM (Resonancia Magnética), la aportacióne indicación de otras tecnologías como el PET(Tomografía por Emisión de Positrones) y se esbozanlas técnicas emergentes basadas en imagen funcional(estudios dinámicos con contraste en RM y estudios dedifusión por RM)(AU)

In the context of a multidisciplinary approach forthe diagnosis and treatment of ovarian cancer, the contributionof radiology includes the following four fundamentalpoints: identification of the lesion, its characterization,study of its extension and evaluation of itsevolution. This article describes the findings and keydiagnostic elements in MDCT (Multidetector ComputedTomography) and MR (Magnetic Resonance), thecontribution and indication of other technologies likePET (Positron Emission Tomography), and outlines theemergent techniques based on functional image analysis(dynamic contrast-enhanced MRI studies and MRIdiffusion studies)(AU)

[Curative effect of stereotactic 186Re endocavitary irradiation on cystic craniopharyngioma].

OBJECTIVE: To evaluate the treatment results of stereotactic (186)Re intracavitary irradiation in the patients with craniopharyngioma. METHODS: Nineteen patients were treated with stereotactic (186)Re intracavitary irradiation, including 12 males and 7 females (average age, 37.2 years). Among them 12 patients had a solitary cyst, whereas 7 patients with mixed structure (e.g., a large cyst with a small solid portion). The mean volume of the cystic portion of the tumor before irradiation was 8390 mm(3). RESULTS: The patients were followed up for 6 months to 3 years. The retraction of the cyst was complete in 7 patients, cyst volume decreased more than 50% in 5 patients and less than 50% in 7 cases. Among the 8 patients with visual acuity deficit before irradiation, 5 were improved. No hypopituitarism occurred in patients with normal pituitary function before treatment. One of the 4 patients with hypopituitarism was improved, 3 of the 5 patients with diabetes insipidus was improved. CONCLUSION: Stereotactic (186)Re endocavitary irradiation for the treatment of cystic craniopharyngioma is a safe and effective procedure.

Image fusion guided brachytherapy of brain tumors.

The paper is the summary of mostly published works of the clinical results of intracavitary Yttrium-90 colloid irradiation of recurrent cystic craniopharyngiomas, and Iodine-125 interstitial irradiation of gliomas, pinealomas, brainstem tumors, recurrent meningeomas, solid craniopharyngiomas and metastases. It concisely demonstrates the usefulness of image fusion in the verification of isotope seeds and catheters, the comparison of 125 Iodine stereotactic brachytherapy and LINAC radiosurgery modalities on physical dose distribution and radiobiological efficacy, and the analysis of volumetric changes after interstitial irradiation of gliomas. Results of the immunohistochemical study deal with the role of microglia/macrophage system in the tissue response to 1-125 interstitial brachytherapy of cerebral gliomas. Due to financial reasons, gamma knife and Linac are not available to many countries and neurosurgical institutes. In the absence of the above mentioned radiosurgical methods, we have shown brachytherapy as an alternative solution in the treatment of different types of inoperable or recurrent brain tumors. The observed results may be noticable at LINAC and gamma knife irradiation too.

Neurosurgical treatment strategies in childhood craniopharyngiomas: is less more?

OBJECTIVE: Craniopharyngiomas in children are typically present in combination with heterogeneous clinical and neuroradiological findings. It has remained highly challenging to choose the optimal treatment strategy with regard to local tumor control and clinical outcome. Here, we analyze different treatment methods and evaluate the results. METHODS: We performed a detailed retrospective evaluation of 32 children <18 years old treated for craniopharyngioma between 1990 and 2008 at the University Hospital Freiburg. Three patient groups could be identified: children treated with microsurgical resection (n=17), with stereotactic cyst drainage and radiotherapy (n=7), and with various combined approaches (n=8). RESULTS: Six of seven children treated with stereotactic cyst punction and radiation are still alive. All of them are in an age-appropriate neuropsychological condition. Two of seven patients in this group have tumor recurrences. Fourteen of the 17 children treated with microsurgical resection show tumor recurrences (p=0.02). Fifteen are alive, and ten out of 17 show an age-appropriate neuropsychological development. The 8.5 years freedom from progression differed from 24% in the resection group to 71% in the cohort treated with stereotactic cyst drainage and radiotherapy (p=0.05). In the third group treated with various approaches, three of eight patients were treated for cystic recurrence. The average follow-up is 5.5 years. CONCLUSIONS: Based on our nonrandomized retrospective monocentric analysis, patients treated with less invasive stereotactic and radiotherapeutical methods have a more favorable long-term clinical outcome compared to children treated with a more radical microsurgical approach. Due to the possible implications of these results, further prospective trials should be encouraged.

Monte Carlo and analytical calculations of dose distributions in craniopharyngioma cysts treated with radiocolloids containing 32P or 186Re.

In radiation treatments of some types of brain tumors, such as craniopharyngiomas, selection of an appropriate radionuclide is critical. The aim of this work was to calculate distributions of dose rates from (32)P and (186)Re in radiocolloids injected into craniopharyngioma cysts. The calculations were performed with the MCNP4C radiation transport code. Analytical calculations based on the Loevinger formula were also performed for (32)P with the MATLAB software. The results of the two techniques for identical models were compared. The effects of the cyst wall type and of the density of the cyst inner fluid were investigated. The (32)P activities required for providing 200, 250, and 300 Gy to cysts of different sizes were calculated.

Surveillance of craniopharyngioma cyst growth in children treated with proton radiotherapy.

PURPOSE: Craniopharyngiomas are benign, slow-growing tumors that frequently contain a cystic component. Even with gross total resection, the cyst can reform and cause symptoms. Fluctuations in cyst volume during radiotherapy (RT) can affect treatment planning and delivery. The aim of this study was to report our experience with cyst enlargement during conformal proton RT for children with craniopharyngioma and to make recommendations regarding mid-treatment surveillance. METHODS AND MATERIALS: Between January 2001 and August 2007, 24 children (aged

Management of cystic craniopharyngiomas with stereotactic endocavitary irradiation using colloidal 186Re: a retrospective study of 48 consecutive patients.

OBJECTIVE: We retrospectively reviewed the results of stereotactic endocavitary irradiation with colloidal 186Re in the treatment of cystic craniopharyngiomas. METHODS: Among 54 consecutive patients included in a 186Re stereotactic endocavitary irradiation procedure, 42 patients (29 male and 13 female; average age, 38.7 years) received therapeutic injection via intracystic catheter introduced under stereotactic conditions. The mean follow-up period was 43 months (range, 8-148 months). Endocavitary irradiation was the primary treatment for 15 patients and an adjuvant treatment for 27 patients. The mean volume before irradiation was 8.07 mm3, and the mean radiation dose was 381 MBq. RESULTS: Cystic mean volume after irradiation was 2.6 cm3 (P < 0.001 with initial volume). The retraction of the cyst was complete for 17 patients (44%) and partial for 17 (44%). In partial retraction, cystic volume decreased more than 50% for 12 (3%) patients and less than 25% (13%) for 5. Cystic volume remained the same or increased for 5 (13%) patients. Concerning visual functions, 12 (44.5%) patients improved and 2 worsened, despite tumor control. No endocrinological deterioration occurred. Among 17 patients with preoperative cognitive dysfunction, 10 improved and 6 had no change. One patient showed memory alteration 4 months after stereotactic endocavitary irradiation despite cyst volume reduction. No mortality occurred. CONCLUSION: 186Re stereotactic endocavitary irradiation for the treatment of cystic craniopharyngiomas is a safe and effective procedure with a tumor control rate greater than 70%. This treatment can be used for first-intention treatment of pure cystic craniopharyngiomas or for second-intention treatment of cystic recurrences.

Management of cystic craniopharyngiomas with intracavitary irradiation with 32P.

BACKGROUND: Cystic craniopharyngiomas are the most frequent intracranial neoplasm of nonglial origin in children. Follow-up data were analyzed to assess the value of intracavitary irradiation with stereotactically applied 32P radioisotopes for the treatment of patients with craniopharyngioma cysts admitted to Shohada Tajrish Hospital, Tehran, Iran, between 1998 and 2005. METHODS: Patients with predominantly cystic craniopharyngiomas, who underwent stereotactic intracavitary irradiation, were followed for tumor response and complications. Beta-emitting 32P isotopes were injected into cysts using a computed tomography-guided and computer-assisted three-dimensional stereotactic treatment planning and application system. The cumulative dose to the inner surface of the cyst wall was 250 Gy. RESULTS: Twenty-two (12 females and 10 males) patients with a mean+/-SD age of 14.0+/-6.6 (range: six to 35) years were studied. The tumor response rate gained with 32P-labeled chromic phosphate was 73% (16 of 22 cysts). The mean+/-SD survival after intracavitary irradiation was 25.4+/-6.8 (95% CI: 12.0 - 38.7) months. CONCLUSION: Intracavitary irradiation using 32P is highly effective in the treatment of cystic craniopharyngiomas. In patients with solitary cyst treated exclusively with this method, it has been the only necessary therapy over a long period. It seems reasonable to recommend intracavitary irradiation as the initial treatment for selected patients and as palliative therapy in those with recurrence.

Long-term results and late complications after intracavitary yttrium-90 colloid irradiation of recurrent cystic craniopharyngiomas.

OBJECTIVE: Data were analyzed to assess the value of stereotactically applied intracystic colloidal yttrium-90 (YTx) for the treatment of recurrent cystic craniopharyngiomas during a 30-year period. METHODS: This article compares data from 73 YTx procedures in 60 patients between 1975 and 2006. The cumulative beta dose aimed at the inner surface of the cyst wall was 300 Gy. RESULTS: After YTx, the initial cyst volumes decreased an average of 79%. In 47, the reduction was more than 80%; in 27 of them, the cyst disappeared completely within 1 year. The mean survival after YTx was 9.4 years (range, 0.7-30 yr). Actuarial survival rates at 5, 10, 15, 20, 25, and 30 years were 81, 61, 45, 18, 2, and 0%, respectively. Late complications of YTx were related to the anatomic localization of the cyst, either presellar and retrosellar, e.g., a presellar (prechiasmatic/suprasellar) localization caused neuro-ophthalmological complications in 5.8% and internal carotid artery injury in 1.6%. The treatment of retrosellar (retrochiasmatic, suprasellar) tumors occasionally induced hypothalamic and/or pontomesencephalothalamic damage obviously by untoward radiation to the so-called perforating arteries. This occurred in 3.2% of these latter patients. CONCLUSION: Despite sporadic complications, intracavitary YTx irradiation is a valuable treatment alternative for craniopharyngioma cysts, sometimes as part of a multimodality management in these tumors, especially in precarious surgical cases.

Dosimetry of (32)P radiocolloid for treatment of cystic craniopharyngioma.

In Tajrish Shohada Hospital, patients with either cystic craniopharyngiomas or cystic astrocytomas have been treated with (32)P radiocolloid by stereotactic procedure. The total activity was prescribed for delivery dose between 200 and 300 Gy to the cyst wall thicknesses of 1-3mm. In this project, MD-55-2 radiochromic film was utilized to determine the dose distribution around the source. The film dosimetry data were compared with Monte Carlo simulated values calculated with MCNP4C code. In addition, the clinical and dosimetric factors such as the cyst volume, and method of radiocolloid injection were evaluated. The required activity and distribution of radial dose in and out of cyst wall have been investigated.