Current practices of craniospinal irradiation techniques in Turkey: a comprehensive dosimetric analysis

OBJECTIVE

This study evaluates various craniospinal irradiation (CSI) techniques used in Turkish centers to understand their advantages, disadvantages and overall effectiveness, with a focus on enhancing dose distribution.

METHODS

Anonymized CT scans of adult and pediatric patients, alongside target volumes and organ-at-risk (OAR) structures, were shared with 25 local radiotherapy centers. They were tasked to develop optimal treatment plans delivering 36 Gy in 20 fractions with 95% PTV coverage, while minimizing OAR exposure. The same CT data was sent to a US proton therapy center for comparison. Various planning systems and treatment techniques (3D conformal RT, IMRT, VMAT, tomotherapy) were utilized. Elekta Proknow software was used to analyze parameters, assess dose distributions, mean doses, conformity index (CI), and homogeneity index (HI) for both target volumes and OARs. Comparisons were made against proton therapy.

RESULTS

All techniques consistently achieved excellent PTV coverage (V95 > 98%) for both adult and pediatric patients. Tomotherapy closely approached ideal Dmean doses for all PTVs, while 3D-CRT had higher Dmean for PTV_brain. Tomotherapy excelled in CI and HI for PTVs. IMRT resulted in lower pediatric heart, kidney, parotid, and eye doses, while 3D-CRT achieved the lowest adult lung doses. Tomotherapy approached proton therapy doses for adult kidneys and thyroid, while IMRT excelled for adult heart, kidney, parotid, esophagus, and eyes.

CONCLUSION

Modern radiotherapy techniques offer improved target coverage and OAR protection. However, 3D techniques are continued to be used for CSI. Notably, proton therapy stands out as the most efficient approach, closely followed by Tomotherapy in terms of achieving superior target coverage and OAR protection.

Sequential pulmonary effects of radiotherapy detected by functional and radiological end points in women with breast cancer

AIMS

To determine the pulmonary effects of locoregional irradiation on clinical and sub-clinical radiographic and functional end points in women with breast cancer, and whether the course of these end points is affected by laterality.

MATERIALS AND METHODS

Twenty patients (10 irradiated on the left side and 10 irradiated on the right side) were prospectively evaluated for changes in pulmonary function tests, Tc-99m DTPA (diethylenetriamine pentaacetic acid) lung clearance scintigraphy and high-resolution computed tomography (HRCT) at 6, 16 and 52 weeks after radiotherapy. Tc-99m DTPA clearance, expressed as the biological half-time, T(1/2), was computed from the time-activity curves for 10 min for each lung. The irradiated lung volume was calculated for each patient.

RESULTS

The mean irradiated lung volume was 6.4% +/- 2 (range 3-11%) for the entire population. In the whole study population, two (10%) patients, who were irradiated on the left side, had mild symptomatic radiation pneumonitis in the follow-up period. There was a statistically significant gradual reduction in all pulmonary function test values during the follow-up period. For patients irradiated on the left side, Tc-99m DTPA clearance T(1/2) values were statistically significantly decreased during the follow-up period (P = 0.03), but the decrease was not statistically significant for patients irradiated on the right side (P = 0.62). Tc-99m DTPA clearance T(1/2) values were statistically significantly decreased in the irradiated lung compared with the opposite lung, and no improvement was seen at week 52 after radiotherapy. The number of patients with changes on HRCT scans increased after radiotherapy, reaching a maximum at 16 weeks, when 80% of patients had changes. There was subsequent partial recovery 52 weeks after radiotherapy.

CONCLUSION

Locoregional irradiation for breast cancer may cause sub-clinical irreversible impairment of radiological and functional pulmonary parameters. The increase in clearance rate of Tc-99m DTPA may be more prominent for patients with left-sided breast cancer.

The potential cardioprotective effects of amifostine in irradiated rats

PURPOSE

The aim of this study is to determine the cardioprotective efficacy of amifostine. The study consists of researching the relationship between plasma brain natriuretic peptide levels and the electrical and morphologic changes in irradiated rats with or without amifostine.

METHODS AND MATERIALS

Sixty Wistar albino rats were divided into 4 groups, and their hearts were given 15 Gy/fraction with (60)Co. In Groups I and II, the rats were killed after 24 hours to detect early effects; in Groups III and IV, the rats were killed 100 days after irradiation to detect late effects. Before irradiation, Groups I and III received 0.9% saline solution, whereas Groups II and IV received amifostine (200 mg/kg). Twenty rats were used as a control group.

RESULTS

On the 100th day, mild myocardial degeneration was detected in 5 rats (33%) from Group III (no amifostine). This percentage was statistically different from that of Group IV (treated with amifostine) and the controls (p = 0.042). There was no statistically significant difference between the mean plasma brain natriuretic peptide values of the groups (p > 0.05). There was no significant difference in electrocardiographies between the groups. There was no correlation between continuous variables.

CONCLUSION

In the amifostine group (IV) on the 100th day, there was no myocardial degeneration, suggesting that amifostine has a cardioprotective effect.